Prof. Dr. Tobias Hoßfeld

Telefon	(0931) 31-86631
Telefax	(0931) 31-86632
E-Mail	tobias.hossfeld@uni-wuerzburg.de (private) cs.international@informatik.uni-wuerzburg.de (Erasmus) studienberatung-inna@informatik.uni-wuerzburg.de (Study: Informatik und Nachhaltigkeit)
Raum	A211
Anschrift	Lehrstuhl für Kommunikationsnetze (Informatik III) Am Hubland D-97074 Würzburg

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An Introduction to Online Video Game QoS and QoE Influencing Factors Metzger, Florian; Geißler, Stefan; Grigorjew, Alexej; Loh, Frank; Moldovan, Christian; Seufert, Michael; Hoßfeld, Tobias in IEEE Communications Surveys & Tutorials (2022).
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Online video games and cloud gaming are rapidly growing in pervasiveness. Their resource demands can put significant stress on the global communication infrastructure. And network conditions are amongst the chief factors that influence one's enjoyment while playing games. This makes it imperative for video games to be considered for network dimensioning, server placement or protocol development. For that reason, in this work we provide an introduction to the technical aspects of video games in general and of their network aspects in particular. This understanding forms the basis for a rich taxonomy of factors that influence and provide context to a video game's Quality of Service (QoS) and Quality of Experience (QoE). The taxonomy covers influence factors from all aspects involved in a video game, from the subjective player and game influence factors to the system and networking influence factors. Finally, this work gives an overview of conducted and ongoing research as well as future research opportunities while taking into account lessons learned from past approaches.

@article{info3-article-2022-16, abstract = {Online video games and cloud gaming are rapidly growing in pervasiveness. Their resource demands can put significant stress on the global communication infrastructure. And network conditions are amongst the chief factors that influence one's enjoyment while playing games. This makes it imperative for video games to be considered for network dimensioning, server placement or protocol development. For that reason, in this work we provide an introduction to the technical aspects of video games in general and of their network aspects in particular. This understanding forms the basis for a rich taxonomy of factors that influence and provide context to a video game's Quality of Service (QoS) and Quality of Experience (QoE). The taxonomy covers influence factors from all aspects involved in a video game, from the subjective player and game influence factors to the system and networking influence factors. Finally, this work gives an overview of conducted and ongoing research as well as future research opportunities while taking into account lessons learned from past approaches.}, author = {Metzger, Florian and Geißler, Stefan and Grigorjew, Alexej and Loh, Frank and Moldovan, Christian and Seufert, Michael and Hoßfeld, Tobias}, journal = {IEEE Communications Surveys & Tutorials}, keywords = {sys:hidden:article}, month = 5, title = {An Introduction to Online Video Game QoS and QoE Influencing Factors}, year = 2022 }

%0 Journal Article %1 info3-article-2022-16 %A Metzger, Florian %A Geißler, Stefan %A Grigorjew, Alexej %A Loh, Frank %A Moldovan, Christian %A Seufert, Michael %A Hoßfeld, Tobias %D 2022 %J IEEE Communications Surveys & Tutorials %T An Introduction to Online Video Game QoS and QoE Influencing Factors %X Online video games and cloud gaming are rapidly growing in pervasiveness. Their resource demands can put significant stress on the global communication infrastructure. And network conditions are amongst the chief factors that influence one's enjoyment while playing games. This makes it imperative for video games to be considered for network dimensioning, server placement or protocol development. For that reason, in this work we provide an introduction to the technical aspects of video games in general and of their network aspects in particular. This understanding forms the basis for a rich taxonomy of factors that influence and provide context to a video game's Quality of Service (QoS) and Quality of Experience (QoE). The taxonomy covers influence factors from all aspects involved in a video game, from the subjective player and game influence factors to the system and networking influence factors. Finally, this work gives an overview of conducted and ongoing research as well as future research opportunities while taking into account lessons learned from past approaches.
Pandemic in the Digital Age: Analyzing WhatsApp Communication Behavior before, during, and after the COVID-19 Lockdown Seufert, Anika; Poignée, Fabian; Hoßfeld, Tobias; Seufert, Michael in Humanities and Social Sciences Communications (2022). 9(1) 140 (1–9).
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The strict restrictions introduced by the COVID-19 lockdowns, which started from March 2020, changed people’s daily lives and habits on many different levels. In this work, we investigate the impact of the lockdown on the communication behavior in the mobile instant messaging application WhatsApp. Our evaluations are based on a large dataset of 2577 private chat histories with 25,378,093 messages from 51,973 users. The analysis of the one-to-one and group conversations confirms that the lockdown severely altered the communication in WhatsApp chats compared to pre-pandemic time ranges. In particular, we observe short-term effects, which caused an increased message frequency in the first lockdown months and a shifted communication activity during the day in March and April 2020. Moreover, we also see long-term effects of the ongoing pandemic situation until February 2021, which indicate a change of communication behavior towards more regular messaging, as well as a persisting change in activity during the day. The results of our work show that even anonymized chat histories can tell us a lot about people’s behavior and especially behavioral changes during the COVID-19 pandemic and thus are of great relevance for behavioral researchers. Furthermore, looking at the pandemic from an Internet provider perspective, these insights can be used during the next pandemic, or if the current COVID-19 situation worsens, to adapt communication networks to the changed usage behavior early on and thus avoid network congestion.

@article{info3-article-2022-14, abstract = {The strict restrictions introduced by the COVID-19 lockdowns, which started from March 2020, changed people’s daily lives and habits on many different levels. In this work, we investigate the impact of the lockdown on the communication behavior in the mobile instant messaging application WhatsApp. Our evaluations are based on a large dataset of 2577 private chat histories with 25,378,093 messages from 51,973 users. The analysis of the one-to-one and group conversations confirms that the lockdown severely altered the communication in WhatsApp chats compared to pre-pandemic time ranges. In particular, we observe short-term effects, which caused an increased message frequency in the first lockdown months and a shifted communication activity during the day in March and April 2020. Moreover, we also see long-term effects of the ongoing pandemic situation until February 2021, which indicate a change of communication behavior towards more regular messaging, as well as a persisting change in activity during the day. The results of our work show that even anonymized chat histories can tell us a lot about people’s behavior and especially behavioral changes during the COVID-19 pandemic and thus are of great relevance for behavioral researchers. Furthermore, looking at the pandemic from an Internet provider perspective, these insights can be used during the next pandemic, or if the current COVID-19 situation worsens, to adapt communication networks to the changed usage behavior early on and thus avoid network congestion.}, author = {Seufert, Anika and Poignée, Fabian and Hoßfeld, Tobias and Seufert, Michael}, journal = {Humanities and Social Sciences Communications}, keywords = {ucn}, month = 4, number = 1, pages = {140 (1-9)}, title = {Pandemic in the Digital Age: Analyzing WhatsApp Communication Behavior before, during, and after the COVID-19 Lockdown}, volume = 9, year = 2022 }

%0 Journal Article %1 info3-article-2022-14 %A Seufert, Anika %A Poignée, Fabian %A Hoßfeld, Tobias %A Seufert, Michael %D 2022 %J Humanities and Social Sciences Communications %N 1 %P 140 (1-9) %T Pandemic in the Digital Age: Analyzing WhatsApp Communication Behavior before, during, and after the COVID-19 Lockdown %V 9 %X The strict restrictions introduced by the COVID-19 lockdowns, which started from March 2020, changed people’s daily lives and habits on many different levels. In this work, we investigate the impact of the lockdown on the communication behavior in the mobile instant messaging application WhatsApp. Our evaluations are based on a large dataset of 2577 private chat histories with 25,378,093 messages from 51,973 users. The analysis of the one-to-one and group conversations confirms that the lockdown severely altered the communication in WhatsApp chats compared to pre-pandemic time ranges. In particular, we observe short-term effects, which caused an increased message frequency in the first lockdown months and a shifted communication activity during the day in March and April 2020. Moreover, we also see long-term effects of the ongoing pandemic situation until February 2021, which indicate a change of communication behavior towards more regular messaging, as well as a persisting change in activity during the day. The results of our work show that even anonymized chat histories can tell us a lot about people’s behavior and especially behavioral changes during the COVID-19 pandemic and thus are of great relevance for behavioral researchers. Furthermore, looking at the pandemic from an Internet provider perspective, these insights can be used during the next pandemic, or if the current COVID-19 situation worsens, to adapt communication networks to the changed usage behavior early on and thus avoid network congestion.
YouTube Dataset on Mobile Streaming for Internet Traffic Modeling and Streaming Analysis Loh, Frank; Wamser, Florian; Poignée, Fabian; Geißler, Stefan; Hoßfeld, Tobias in Nature, Scientific Data (2022).
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Around 4.9 billion Internet users worldwide watch billions of hours of online video every day. As a result, streaming is by far the predominant type of traffic in communication networks. According to Google statistics, three out of five video views come from mobile devices. Thus, in view of the continuous technological advances in end devices and increasing mobile use, datasets for mobile streaming are indispensable in research but only sparsely dealt with in literature so far. With this public dataset, we provide 1,081 hours of time-synchronous video measurements at network, transport, and application layer with the native YouTube streaming client on mobile devices. The dataset includes 80 network scenarios with 171 different individual bandwidth settings measured in 5,181 runs with limited bandwidth, 1,939 runs with emulated 3 G/4 G traces, and 4,022 runs with pre-defined bandwidth changes. This corresponds to 332 GB video payload. We present the most relevant quality indicators for scientific use, i.e., initial playback delay, streaming video quality, adaptive video quality changes, video rebuffering events, and streaming phases.

@article{info3-article-2022-17, abstract = {Around 4.9 billion Internet users worldwide watch billions of hours of online video every day. As a result, streaming is by far the predominant type of traffic in communication networks. According to Google statistics, three out of five video views come from mobile devices. Thus, in view of the continuous technological advances in end devices and increasing mobile use, datasets for mobile streaming are indispensable in research but only sparsely dealt with in literature so far. With this public dataset, we provide 1,081 hours of time-synchronous video measurements at network, transport, and application layer with the native YouTube streaming client on mobile devices. The dataset includes 80 network scenarios with 171 different individual bandwidth settings measured in 5,181 runs with limited bandwidth, 1,939 runs with emulated 3 G/4 G traces, and 4,022 runs with pre-defined bandwidth changes. This corresponds to 332 GB video payload. We present the most relevant quality indicators for scientific use, i.e., initial playback delay, streaming video quality, adaptive video quality changes, video rebuffering events, and streaming phases.}, author = {Loh, Frank and Wamser, Florian and Poignée, Fabian and Geißler, Stefan and Hoßfeld, Tobias}, journal = {Nature, Scientific Data}, keywords = {sys:hidden:article}, month = 6, title = {YouTube Dataset on Mobile Streaming for Internet Traffic Modeling and Streaming Analysis}, year = 2022 }

%0 Journal Article %1 info3-article-2022-17 %A Loh, Frank %A Wamser, Florian %A Poignée, Fabian %A Geißler, Stefan %A Hoßfeld, Tobias %D 2022 %J Nature, Scientific Data %T YouTube Dataset on Mobile Streaming for Internet Traffic Modeling and Streaming Analysis %X Around 4.9 billion Internet users worldwide watch billions of hours of online video every day. As a result, streaming is by far the predominant type of traffic in communication networks. According to Google statistics, three out of five video views come from mobile devices. Thus, in view of the continuous technological advances in end devices and increasing mobile use, datasets for mobile streaming are indispensable in research but only sparsely dealt with in literature so far. With this public dataset, we provide 1,081 hours of time-synchronous video measurements at network, transport, and application layer with the native YouTube streaming client on mobile devices. The dataset includes 80 network scenarios with 171 different individual bandwidth settings measured in 5,181 runs with limited bandwidth, 1,939 runs with emulated 3 G/4 G traces, and 4,022 runs with pre-defined bandwidth changes. This corresponds to 332 GB video payload. We present the most relevant quality indicators for scientific use, i.e., initial playback delay, streaming video quality, adaptive video quality changes, video rebuffering events, and streaming phases.
Valid Statements by the Crowd: Statistical Measures for Precision in Crowdsourced Mobile Measurements Wamser, Florian; Seufert, Anika; Hall, Andrew; Wunderer, Stefan; Hoßfeld, Tobias in Network (2021). 1(2) 215–232.
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Crowdsourced network measurements (CNMs) are becoming increasingly popular as they assess the performance of a mobile network from the end user’s perspective on a large scale. Here, network measurements are performed directly on the end-users’ devices, thus taking advantage of the real-world conditions end-users encounter. However, this type of uncontrolled measurement raises questions about its validity and reliability. The problem lies in the nature of this type of data collection. In CNMs, mobile network subscribers are involved to a large extent in the measurement process, and collect data themselves for the operator. The collection of data on user devices in arbitrary locations and at uncontrolled times requires means to ensure validity and reliability. To address this issue, our paper defines concepts and guidelines for analyzing the precision of CNMs; specifically, the number of measurements required to make valid statements. In addition to the formal definition of the aspect, we illustrate the problem and use an extensive sample data set to show possible assessment approaches. This data set consists of more than 20.4 million crowdsourced mobile measurements from across France, measured by a commercial data provider.

@article{info3-article-2021-5, abstract = {Crowdsourced network measurements (CNMs) are becoming increasingly popular as they assess the performance of a mobile network from the end user’s perspective on a large scale. Here, network measurements are performed directly on the end-users’ devices, thus taking advantage of the real-world conditions end-users encounter. However, this type of uncontrolled measurement raises questions about its validity and reliability. The problem lies in the nature of this type of data collection. In CNMs, mobile network subscribers are involved to a large extent in the measurement process, and collect data themselves for the operator. The collection of data on user devices in arbitrary locations and at uncontrolled times requires means to ensure validity and reliability. To address this issue, our paper defines concepts and guidelines for analyzing the precision of CNMs; specifically, the number of measurements required to make valid statements. In addition to the formal definition of the aspect, we illustrate the problem and use an extensive sample data set to show possible assessment approaches. This data set consists of more than 20.4 million crowdsourced mobile measurements from across France, measured by a commercial data provider.}, author = {Wamser, Florian and Seufert, Anika and Hall, Andrew and Wunderer, Stefan and Hoßfeld, Tobias}, journal = {Network}, keywords = {can}, month = 9, number = 2, pages = {215–232}, title = {Valid Statements by the Crowd: Statistical Measures for Precision in Crowdsourced Mobile Measurements}, volume = 1, year = 2021 }

%0 Journal Article %1 info3-article-2021-5 %A Wamser, Florian %A Seufert, Anika %A Hall, Andrew %A Wunderer, Stefan %A Hoßfeld, Tobias %D 2021 %J Network %N 2 %P 215--232 %T Valid Statements by the Crowd: Statistical Measures for Precision in Crowdsourced Mobile Measurements %V 1 %X Crowdsourced network measurements (CNMs) are becoming increasingly popular as they assess the performance of a mobile network from the end user’s perspective on a large scale. Here, network measurements are performed directly on the end-users’ devices, thus taking advantage of the real-world conditions end-users encounter. However, this type of uncontrolled measurement raises questions about its validity and reliability. The problem lies in the nature of this type of data collection. In CNMs, mobile network subscribers are involved to a large extent in the measurement process, and collect data themselves for the operator. The collection of data on user devices in arbitrary locations and at uncontrolled times requires means to ensure validity and reliability. To address this issue, our paper defines concepts and guidelines for analyzing the precision of CNMs; specifically, the number of measurements required to make valid statements. In addition to the formal definition of the aspect, we illustrate the problem and use an extensive sample data set to show possible assessment approaches. This data set consists of more than 20.4 million crowdsourced mobile measurements from across France, measured by a commercial data provider.
Discrete-Time Modeling of NFV Accelerators that Exploit Batched Processing Geissler, Stefan; Lange, Stanislav; Linguaglossa, Leonardo; Rossi, Dario; Zinner, Thomas; Hoßfeld, Tobias in ACM Transactions on Modeling and Performance Evaluation of Computing Systems (2021). 6(3) 1–27.
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@article{info3-article-2021-12, author = {Geissler, Stefan and Lange, Stanislav and Linguaglossa, Leonardo and Rossi, Dario and Zinner, Thomas and Hoßfeld, Tobias}, journal = {ACM Transactions on Modeling and Performance Evaluation of Computing Systems}, keywords = {can}, month = 9, number = 3, pages = {1-27}, title = {Discrete-Time Modeling of NFV Accelerators that Exploit Batched Processing}, volume = 6, year = 2021 }

%0 Journal Article %1 info3-article-2021-12 %A Geissler, Stefan %A Lange, Stanislav %A Linguaglossa, Leonardo %A Rossi, Dario %A Zinner, Thomas %A Hoßfeld, Tobias %D 2021 %J ACM Transactions on Modeling and Performance Evaluation of Computing Systems %N 3 %P 1-27 %T Discrete-Time Modeling of NFV Accelerators that Exploit Batched Processing %V 6
Improving Web QoE Monitoring for Encrypted Network Traffic through Time Series Modeling Wehner, Nikolas; Seufert, Michael; Schüler, Joshua; Wassermann, Sarah; Casas, Pedro; Hoßfeld, Tobias in ACM SIGMETRICS Performance Evaluation Review (2021). 48(4) 37–40.
- [ Abstract ]
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This paper addresses the problem of Quality of Experience (QoE) monitoring for web browsing. In particular, the inference of common Web QoE metrics such as Speed Index (SI) is investigated. Based on a large dataset collected with open web-measurement platforms on different device-types, a unique feature set is designed and used to estimate the RUMSI -- an efficient approximation to SI, with machine-learning based regression and classification approaches. Results indicate that it is possible to estimate the RUMSI accurately, and that in particular, recurrent neural networks are highly suitable for the task, as they capture the network dynamics more precisely.

@article{info3-article-2020-4, abstract = {This paper addresses the problem of Quality of Experience (QoE) monitoring for web browsing. In particular, the inference of common Web QoE metrics such as Speed Index (SI) is investigated. Based on a large dataset collected with open web-measurement platforms on different device-types, a unique feature set is designed and used to estimate the RUMSI – an efficient approximation to SI, with machine-learning based regression and classification approaches. Results indicate that it is possible to estimate the RUMSI accurately, and that in particular, recurrent neural networks are highly suitable for the task, as they capture the network dynamics more precisely.}, author = {Wehner, Nikolas and Seufert, Michael and Schüler, Joshua and Wassermann, Sarah and Casas, Pedro and Hoßfeld, Tobias}, journal = {ACM SIGMETRICS Performance Evaluation Review}, keywords = {ucn}, month = 3, number = 4, pages = {37-40}, title = {Improving Web QoE Monitoring for Encrypted Network Traffic through Time Series Modeling}, volume = 48, year = 2021 }

%0 Journal Article %1 info3-article-2020-4 %A Wehner, Nikolas %A Seufert, Michael %A Schüler, Joshua %A Wassermann, Sarah %A Casas, Pedro %A Hoßfeld, Tobias %D 2021 %J ACM SIGMETRICS Performance Evaluation Review %N 4 %P 37-40 %T Improving Web QoE Monitoring for Encrypted Network Traffic through Time Series Modeling %V 48 %X This paper addresses the problem of Quality of Experience (QoE) monitoring for web browsing. In particular, the inference of common Web QoE metrics such as Speed Index (SI) is investigated. Based on a large dataset collected with open web-measurement platforms on different device-types, a unique feature set is designed and used to estimate the RUMSI -- an efficient approximation to SI, with machine-learning based regression and classification approaches. Results indicate that it is possible to estimate the RUMSI accurately, and that in particular, recurrent neural networks are highly suitable for the task, as they capture the network dynamics more precisely.
Energy-Aware Service Function Chain Embedding in Edge-Cloud Environments for IoT Applications Nguyen Huu, Thanh; TrungKien, Nguyen; Van Hoa, Ngo; Thu Huong, Truong; Wamser, Florian; Hoßfeld, Tobias in IEEE Internet of Things Journal (2021).
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The implementation of IoT applications faces several challenges in practice, such as compliance with QoS requirements, resource constraints and energy consumption. In this context, the joint paradigm for IoT applications can resolve some of the issues arising in pure cloud computing scenarios, such as those related to latency, energy or privacy. Therefore, an environment could be promising for resource and energy-efficient IoT applications that implement VNF bound together into SFC. However, a resource and energy efficient SFC placement requires smart SFC embedding mechanisms in the environment, as several challenges arise, such as IoT service chain modeling and evaluation, the trade-off between resource allocation, energy efficiency and performance, and the resource dynamics. In this article, we address issues in modeling resource and energy utilization for IoT applications in environments. A smart traffic monitoring IP camera system is deployed as a use case for a realistic modeling of a service chain. The system is implemented in our testbed, which is designed and developed specifically to model and investigate the resource and energy utilization of SFC embedding strategies. A resource and energy-aware SFC strategy in the environment for IoT applications is then proposed. Our algorithm is able to cope with dynamic load and resource situations emerging from dynamic SFC requests. The strategy is evaluated systematically in terms of acceptance ratio of SFC requests, resource efficiency and utilization, power consumption, and VNF migrations depending on the offered system load. Results show that our strategy outperforms some existing approaches in terms of resource and energy efficiency, thus it overcomes the relevant challenges from practice and meets the demands of IoT applications.

@article{info3-article-2021-2, abstract = {The implementation of IoT applications faces several challenges in practice, such as compliance with QoS requirements, resource constraints and energy consumption. In this context, the joint paradigm for IoT applications can resolve some of the issues arising in pure cloud computing scenarios, such as those related to latency, energy or privacy. Therefore, an environment could be promising for resource and energy-efficient IoT applications that implement VNF bound together into SFC. However, a resource and energy efficient SFC placement requires smart SFC embedding mechanisms in the environment, as several challenges arise, such as IoT service chain modeling and evaluation, the trade-off between resource allocation, energy efficiency and performance, and the resource dynamics. In this article, we address issues in modeling resource and energy utilization for IoT applications in environments. A smart traffic monitoring IP camera system is deployed as a use case for a realistic modeling of a service chain. The system is implemented in our testbed, which is designed and developed specifically to model and investigate the resource and energy utilization of SFC embedding strategies. A resource and energy-aware SFC strategy in the environment for IoT applications is then proposed. Our algorithm is able to cope with dynamic load and resource situations emerging from dynamic SFC requests. The strategy is evaluated systematically in terms of acceptance ratio of SFC requests, resource efficiency and utilization, power consumption, and VNF migrations depending on the offered system load. Results show that our strategy outperforms some existing approaches in terms of resource and energy efficiency, thus it overcomes the relevant challenges from practice and meets the demands of IoT applications.}, author = {Nguyen Huu, Thanh and TrungKien, Nguyen and Van Hoa, Ngo and Thu Huong, Truong and Wamser, Florian and Hoßfeld, Tobias}, journal = {IEEE Internet of Things Journal}, keywords = {sys:hidden:article}, month = 3, title = {Energy-Aware Service Function Chain Embedding in Edge-Cloud Environments for IoT Applications}, year = 2021 }

%0 Journal Article %1 info3-article-2021-2 %A Nguyen Huu, Thanh %A TrungKien, Nguyen %A Van Hoa, Ngo %A Thu Huong, Truong %A Wamser, Florian %A Hoßfeld, Tobias %D 2021 %J IEEE Internet of Things Journal %T Energy-Aware Service Function Chain Embedding in Edge-Cloud Environments for IoT Applications %X The implementation of IoT applications faces several challenges in practice, such as compliance with QoS requirements, resource constraints and energy consumption. In this context, the joint paradigm for IoT applications can resolve some of the issues arising in pure cloud computing scenarios, such as those related to latency, energy or privacy. Therefore, an environment could be promising for resource and energy-efficient IoT applications that implement VNF bound together into SFC. However, a resource and energy efficient SFC placement requires smart SFC embedding mechanisms in the environment, as several challenges arise, such as IoT service chain modeling and evaluation, the trade-off between resource allocation, energy efficiency and performance, and the resource dynamics. In this article, we address issues in modeling resource and energy utilization for IoT applications in environments. A smart traffic monitoring IP camera system is deployed as a use case for a realistic modeling of a service chain. The system is implemented in our testbed, which is designed and developed specifically to model and investigate the resource and energy utilization of SFC embedding strategies. A resource and energy-aware SFC strategy in the environment for IoT applications is then proposed. Our algorithm is able to cope with dynamic load and resource situations emerging from dynamic SFC requests. The strategy is evaluated systematically in terms of acceptance ratio of SFC requests, resource efficiency and utilization, power consumption, and VNF migrations depending on the offered system load. Results show that our strategy outperforms some existing approaches in terms of resource and energy efficiency, thus it overcomes the relevant challenges from practice and meets the demands of IoT applications.
Uplink vs. Downlink: Machine Learning-Based Quality Prediction for HTTP Adaptive Video Streaming Loh, Frank; Poignée, Fabian; Wamser, Florian; Leidinger, Ferdinand; Hoßfeld, Tobias in Sensors (2021). 21(12) 4172.
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Streaming video is responsible for the bulk of Internet traffic these days. For this reason, Internet providers and network operators try to make predictions and assessments about the streaming quality for an end user. Current monitoring solutions are based on a variety of different machine learning approaches. The challenge for providers and operators nowadays is that existing approaches require large amounts of data. In this work, the most relevant quality of experience metrics, i.e., the initial playback delay, the video streaming quality, video quality changes, and video rebuffering events, are examined using a voluminous data set of more than 13,000 YouTube video streaming runs that were collected with the native YouTube mobile app. Three Machine Learning models are developed and compared to estimate playback behavior based on uplink request information. The main focus has been on developing a lightweight approach using as few features and as little data as possible, while maintaining state-of-the-art performance.

@article{info3-article-2021-3, abstract = {Streaming video is responsible for the bulk of Internet traffic these days. For this reason, Internet providers and network operators try to make predictions and assessments about the streaming quality for an end user. Current monitoring solutions are based on a variety of different machine learning approaches. The challenge for providers and operators nowadays is that existing approaches require large amounts of data. In this work, the most relevant quality of experience metrics, i.e., the initial playback delay, the video streaming quality, video quality changes, and video rebuffering events, are examined using a voluminous data set of more than 13,000 YouTube video streaming runs that were collected with the native YouTube mobile app. Three Machine Learning models are developed and compared to estimate playback behavior based on uplink request information. The main focus has been on developing a lightweight approach using as few features and as little data as possible, while maintaining state-of-the-art performance.}, author = {Loh, Frank and Poignée, Fabian and Wamser, Florian and Leidinger, Ferdinand and Hoßfeld, Tobias}, journal = {Sensors}, keywords = {can}, number = 12, pages = 4172, title = {Uplink vs. Downlink: Machine Learning-Based Quality Prediction for HTTP Adaptive Video Streaming}, volume = 21, year = 2021 }

%0 Journal Article %1 info3-article-2021-3 %A Loh, Frank %A Poignée, Fabian %A Wamser, Florian %A Leidinger, Ferdinand %A Hoßfeld, Tobias %D 2021 %J Sensors %N 12 %P 4172 %T Uplink vs. Downlink: Machine Learning-Based Quality Prediction for HTTP Adaptive Video Streaming %V 21 %X Streaming video is responsible for the bulk of Internet traffic these days. For this reason, Internet providers and network operators try to make predictions and assessments about the streaming quality for an end user. Current monitoring solutions are based on a variety of different machine learning approaches. The challenge for providers and operators nowadays is that existing approaches require large amounts of data. In this work, the most relevant quality of experience metrics, i.e., the initial playback delay, the video streaming quality, video quality changes, and video rebuffering events, are examined using a voluminous data set of more than 13,000 YouTube video streaming runs that were collected with the native YouTube mobile app. Three Machine Learning models are developed and compared to estimate playback behavior based on uplink request information. The main focus has been on developing a lightweight approach using as few features and as little data as possible, while maintaining state-of-the-art performance.
Cumulative Quality Modeling for HTTP Adaptive Streaming Tran, Huyen TT; Pham Ngoc, Nam; Hoßfeld, Tobias; Seufert, Michael; Thang, Truong Cong in ACM Transactions on Multimedia Computing, Communications, and Applications (2021). 17(1) 22 (1–24).
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@article{info3-article-2021-1, author = {Tran, Huyen TT and Pham Ngoc, Nam and Hoßfeld, Tobias and Seufert, Michael and Thang, Truong Cong}, journal = {ACM Transactions on Multimedia Computing, Communications, and Applications}, keywords = {ucn}, month = 4, number = 1, pages = {22 (1-24)}, title = {Cumulative Quality Modeling for HTTP Adaptive Streaming}, volume = 17, year = 2021 }

%0 Journal Article %1 info3-article-2021-1 %A Tran, Huyen TT %A Pham Ngoc, Nam %A Hoßfeld, Tobias %A Seufert, Michael %A Thang, Truong Cong %D 2021 %J ACM Transactions on Multimedia Computing, Communications, and Applications %N 1 %P 22 (1-24) %T Cumulative Quality Modeling for HTTP Adaptive Streaming %V 17
LoRaPlan: A Software to Evaluate Gateway Placement in LoRaWAN Loh, Frank; Mehling, Noah; Metzger, Florian; Hoßfeld, Tobias in 17th International Conference on Network and Service Management (2021).
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Long Range Wide Area Network (LoRaWAN) is one of the fastest growing Internet of Things (IoT) access network solutions. One major challenge in current LoRaWAN planning is message collision due to the random channel access. To study the collision behavior in LoRaWAN, we present LoRaPlan in this demonstration. LoRaPlan is a software to evaluate gateway placement decisions by studying the collision probability. Therefore, sensor and gateway locations can be imported to create a LoRaWAN. Furthermore, existing networks can be extended by additional gateways. Based on this setup, network coverage, network quality with regard to the number of sensors a single gateway has to manage, and also transmission quality and collision probabilities can be studied. In this demonstration, first the process of network creation with gateway and sensor import and additional manual gateway placement in LoRaPlan is presented. Different adjustable parameters are shown and the influence on network coverage and collision probability is discussed. At the end of this demonstration, it is possible for the audience to place their own gateways and evaluate own placements by means of collision probability and the coverage.

@article{info3-article-2021-11, abstract = {Long Range Wide Area Network (LoRaWAN) is one of the fastest growing Internet of Things (IoT) access network solutions. One major challenge in current LoRaWAN planning is message collision due to the random channel access. To study the collision behavior in LoRaWAN, we present LoRaPlan in this demonstration. LoRaPlan is a software to evaluate gateway placement decisions by studying the collision probability. Therefore, sensor and gateway locations can be imported to create a LoRaWAN. Furthermore, existing networks can be extended by additional gateways. Based on this setup, network coverage, network quality with regard to the number of sensors a single gateway has to manage, and also transmission quality and collision probabilities can be studied. In this demonstration, first the process of network creation with gateway and sensor import and additional manual gateway placement in LoRaPlan is presented. Different adjustable parameters are shown and the influence on network coverage and collision probability is discussed. At the end of this demonstration, it is possible for the audience to place their own gateways and evaluate own placements by means of collision probability and the coverage.}, author = {Loh, Frank and Mehling, Noah and Metzger, Florian and Hoßfeld, Tobias}, journal = {17th International Conference on Network and Service Management}, keywords = {sys:hidden:article}, month = 10, title = {LoRaPlan: A Software to Evaluate Gateway Placement in LoRaWAN}, year = 2021 }

%0 Journal Article %1 info3-article-2021-11 %A Loh, Frank %A Mehling, Noah %A Metzger, Florian %A Hoßfeld, Tobias %D 2021 %J 17th International Conference on Network and Service Management %T LoRaPlan: A Software to Evaluate Gateway Placement in LoRaWAN %X Long Range Wide Area Network (LoRaWAN) is one of the fastest growing Internet of Things (IoT) access network solutions. One major challenge in current LoRaWAN planning is message collision due to the random channel access. To study the collision behavior in LoRaWAN, we present LoRaPlan in this demonstration. LoRaPlan is a software to evaluate gateway placement decisions by studying the collision probability. Therefore, sensor and gateway locations can be imported to create a LoRaWAN. Furthermore, existing networks can be extended by additional gateways. Based on this setup, network coverage, network quality with regard to the number of sensors a single gateway has to manage, and also transmission quality and collision probabilities can be studied. In this demonstration, first the process of network creation with gateway and sensor import and additional manual gateway placement in LoRaPlan is presented. Different adjustable parameters are shown and the influence on network coverage and collision probability is discussed. At the end of this demonstration, it is possible for the audience to place their own gateways and evaluate own placements by means of collision probability and the coverage.
In vitro vs in vivo: does the study’s interface design influence crowdsourced video QoE? Borchert, Kathrin; Seufert, Anika; Gamboa, Edwin; Hirth, Matthias; Hoßfeld, Tobias in Quality and User Experience (2020).
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Evaluating the Quality of Experience (QoE) of video streaming and its influence factors has become paramount for streaming providers, as they want to maintain high satisfaction for their customers. In this context, crowdsourced user studies became a valuable tool to evaluate different factors which can affect the perceived user experience on a large scale. In general, most of these crowdsourcing studies either use, what we refer to, as an in vivo or an in vitro interface design. In vivo design means that the study participant has to rate the QoE of a video that is embedded in an application similar to a real streaming service, e.g., YouTube or Netflix. In vitro design refers to a setting, in which the video stream is separated from a specific service and thus, the video plays on a plain background. Although these interface designs vary widely, the results are often compared and generalized. In this work, we use a crowdsourcing study to investigate the influence of three interface design alternatives, an in vitro and two in vivo designs with different levels of interactiveness, on the perceived video QoE. Contrary to our expectations, the results indicate that there is no significant influence of the study’s interface design in general on the video experience. Furthermore, we found that the in vivo design does not reduce the test takers’ attentiveness. However, we observed that participants who interacted with the test interface reported a higher video QoE than other groups.

@article{info3-article-2020-6, abstract = {Evaluating the Quality of Experience (QoE) of video streaming and its influence factors has become paramount for streaming providers, as they want to maintain high satisfaction for their customers. In this context, crowdsourced user studies became a valuable tool to evaluate different factors which can affect the perceived user experience on a large scale. In general, most of these crowdsourcing studies either use, what we refer to, as an in vivo or an in vitro interface design. In vivo design means that the study participant has to rate the QoE of a video that is embedded in an application similar to a real streaming service, e.g., YouTube or Netflix. In vitro design refers to a setting, in which the video stream is separated from a specific service and thus, the video plays on a plain background. Although these interface designs vary widely, the results are often compared and generalized. In this work, we use a crowdsourcing study to investigate the influence of three interface design alternatives, an in vitro and two in vivo designs with different levels of interactiveness, on the perceived video QoE. Contrary to our expectations, the results indicate that there is no significant influence of the study’s interface design in general on the video experience. Furthermore, we found that the in vivo design does not reduce the test takers’ attentiveness. However, we observed that participants who interacted with the test interface reported a higher video QoE than other groups.}, author = {Borchert, Kathrin and Seufert, Anika and Gamboa, Edwin and Hirth, Matthias and Hoßfeld, Tobias}, journal = {Quality and User Experience}, keywords = {ua-net}, month = 11, title = {In vitro vs in vivo: does the study’s interface design influence crowdsourced video QoE?}, year = 2020 }

%0 Journal Article %1 info3-article-2020-6 %A Borchert, Kathrin %A Seufert, Anika %A Gamboa, Edwin %A Hirth, Matthias %A Hoßfeld, Tobias %D 2020 %J Quality and User Experience %T In vitro vs in vivo: does the study’s interface design influence crowdsourced video QoE? %X Evaluating the Quality of Experience (QoE) of video streaming and its influence factors has become paramount for streaming providers, as they want to maintain high satisfaction for their customers. In this context, crowdsourced user studies became a valuable tool to evaluate different factors which can affect the perceived user experience on a large scale. In general, most of these crowdsourcing studies either use, what we refer to, as an in vivo or an in vitro interface design. In vivo design means that the study participant has to rate the QoE of a video that is embedded in an application similar to a real streaming service, e.g., YouTube or Netflix. In vitro design refers to a setting, in which the video stream is separated from a specific service and thus, the video plays on a plain background. Although these interface designs vary widely, the results are often compared and generalized. In this work, we use a crowdsourcing study to investigate the influence of three interface design alternatives, an in vitro and two in vivo designs with different levels of interactiveness, on the perceived video QoE. Contrary to our expectations, the results indicate that there is no significant influence of the study’s interface design in general on the video experience. Furthermore, we found that the in vivo design does not reduce the test takers’ attentiveness. However, we observed that participants who interacted with the test interface reported a higher video QoE than other groups.
Deriving QoE in systems: from fundamental relationships to a QoE‑based Service‑level Quality Index Hoßfeld, Tobias; Heegaard, Poul E.; Skorin-Kapov, Lea; Varela, Martin in Springer Quality and User Experience (2020). 5(7) https://rdcu.be/b483m.
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With Quality of Experience (QoE) research having made significant advances over the years, service and network providers aim at user-centric evaluation of the services provided in their system. The question arises how to derive QoE in systems. In the context of subjective user studies conducted to derive relationships between influence factors and QoE, user diversity leads to varying distributions of user rating scores for different test conditions. Such models are commonly exploited by providers to derive various QoE metrics in their system, such as expected QoE, or the percentage of users rating above a certain threshold. The question then becomes how to combine (a) user rating distributions obtained from subjective studies, and (b) system parameter distributions, so as to obtain the actual observed QoE distribution in the system? Moreover, how can various QoE metrics of interest in the system be derived? We prove fundamental relationships for the derivation of QoE in systems, thus providing an important link between the QoE community and the systems community. In our numerical examples, we focus mainly on QoE metrics. We furthermore provide a more generalized view on quantifying the quality of systems by defining a QoE-based Service-level Quality Index. This index exploits the fact that quality can be seen as a proxy measure for utility. Following the assumption that not all user sessions should be weighted equally, we aim to provide a generic framework that can be utilized to quantify the overall utility of a service delivered by a system.

@article{info3-article-2020-2, abstract = {With Quality of Experience (QoE) research having made significant advances over the years, service and network providers aim at user-centric evaluation of the services provided in their system. The question arises how to derive QoE in systems. In the context of subjective user studies conducted to derive relationships between influence factors and QoE, user diversity leads to varying distributions of user rating scores for different test conditions. Such models are commonly exploited by providers to derive various QoE metrics in their system, such as expected QoE, or the percentage of users rating above a certain threshold. The question then becomes how to combine (a) user rating distributions obtained from subjective studies, and (b) system parameter distributions, so as to obtain the actual observed QoE distribution in the system? Moreover, how can various QoE metrics of interest in the system be derived? We prove fundamental relationships for the derivation of QoE in systems, thus providing an important link between the QoE community and the systems community. In our numerical examples, we focus mainly on QoE metrics. We furthermore provide a more generalized view on quantifying the quality of systems by defining a QoE-based Service-level Quality Index. This index exploits the fact that quality can be seen as a proxy measure for utility. Following the assumption that not all user sessions should be weighted equally, we aim to provide a generic framework that can be utilized to quantify the overall utility of a service delivered by a system.}, author = {Hoßfeld, Tobias and Heegaard, Poul E. and Skorin-Kapov, Lea and Varela, Martin}, journal = {Springer Quality and User Experience}, keywords = {sys:hidden:article}, month = 7, number = 7, pages = {https://rdcu.be/b483m}, title = {Deriving QoE in systems: from fundamental relationships to a QoE‑based Service‑level Quality Index}, volume = 5, year = 2020 }

%0 Journal Article %1 info3-article-2020-2 %A Hoßfeld, Tobias %A Heegaard, Poul E. %A Skorin-Kapov, Lea %A Varela, Martin %D 2020 %J Springer Quality and User Experience %N 7 %P https://rdcu.be/b483m %T Deriving QoE in systems: from fundamental relationships to a QoE‑based Service‑level Quality Index %V 5 %X With Quality of Experience (QoE) research having made significant advances over the years, service and network providers aim at user-centric evaluation of the services provided in their system. The question arises how to derive QoE in systems. In the context of subjective user studies conducted to derive relationships between influence factors and QoE, user diversity leads to varying distributions of user rating scores for different test conditions. Such models are commonly exploited by providers to derive various QoE metrics in their system, such as expected QoE, or the percentage of users rating above a certain threshold. The question then becomes how to combine (a) user rating distributions obtained from subjective studies, and (b) system parameter distributions, so as to obtain the actual observed QoE distribution in the system? Moreover, how can various QoE metrics of interest in the system be derived? We prove fundamental relationships for the derivation of QoE in systems, thus providing an important link between the QoE community and the systems community. In our numerical examples, we focus mainly on QoE metrics. We furthermore provide a more generalized view on quantifying the quality of systems by defining a QoE-based Service-level Quality Index. This index exploits the fact that quality can be seen as a proxy measure for utility. Following the assumption that not all user sessions should be weighted equally, we aim to provide a generic framework that can be utilized to quantify the overall utility of a service delivered by a system.
Modeling of Aggregated IoT Traffic and Its Application to an IoT Cloud Metzger, Florian; Hoßfeld, Tobias; Bauer, André; Kounev, Samuel; Heegaard, Poul E. in Proceedings of the IEEE (2019). 107(4) 679–694.
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As the Internet of Things (IoT) continues to gain traction in telecommunication networks, a very large number of devices are expected to be connected and used in the near future. In order to appropriately plan and dimension the network, as well as the back-end cloud systems and the resulting signaling load, traffic models are employed. These models are designed to accurately capture and predict the properties of IoT traffic in a concise manner. To achieve this, Poisson process approximations, based on the Palm–Khintchine theorem, have often been used in the past. Due to the scale (and the difference in scales in various IoT networks) of the modeled systems, the fidelity of this approximation is crucial, as, in practice, it is very challenging to accurately measure or simulate large-scale IoT deployments. The main goal of this paper is to understand the level of accuracy of the Poisson approximation model. To this end, we first survey both common IoT network properties and network scales as well as traffic types. Second, we explain and discuss the Palm–Khintiche theorem, how it is applied to the problem, and which inaccuracies can occur when using it. Based on this, we derive guidelines as to when a Poisson process can be assumed for aggregated periodic IoT traffic. Finally, we evaluate our approach in the context of an IoT cloud scaler use case.

@article{info3-article-2019-3, abstract = {As the Internet of Things (IoT) continues to gain traction in telecommunication networks, a very large number of devices are expected to be connected and used in the near future. In order to appropriately plan and dimension the network, as well as the back-end cloud systems and the resulting signaling load, traffic models are employed. These models are designed to accurately capture and predict the properties of IoT traffic in a concise manner. To achieve this, Poisson process approximations, based on the Palm–Khintchine theorem, have often been used in the past. Due to the scale (and the difference in scales in various IoT networks) of the modeled systems, the fidelity of this approximation is crucial, as, in practice, it is very challenging to accurately measure or simulate large-scale IoT deployments. The main goal of this paper is to understand the level of accuracy of the Poisson approximation model. To this end, we first survey both common IoT network properties and network scales as well as traffic types. Second, we explain and discuss the Palm–Khintiche theorem, how it is applied to the problem, and which inaccuracies can occur when using it. Based on this, we derive guidelines as to when a Poisson process can be assumed for aggregated periodic IoT traffic. Finally, we evaluate our approach in the context of an IoT cloud scaler use case.}, author = {Metzger, Florian and Hoßfeld, Tobias and Bauer, André and Kounev, Samuel and Heegaard, Poul E.}, journal = {Proceedings of the IEEE}, keywords = {doi:10.1109/JPROC.2019.2901578}, month = 4, number = 4, pages = {679-694}, title = {Modeling of Aggregated IoT Traffic and Its Application to an IoT Cloud}, volume = 107, year = 2019 }

%0 Journal Article %1 info3-article-2019-3 %A Metzger, Florian %A Hoßfeld, Tobias %A Bauer, André %A Kounev, Samuel %A Heegaard, Poul E. %D 2019 %J Proceedings of the IEEE %N 4 %P 679-694 %T Modeling of Aggregated IoT Traffic and Its Application to an IoT Cloud %V 107 %X As the Internet of Things (IoT) continues to gain traction in telecommunication networks, a very large number of devices are expected to be connected and used in the near future. In order to appropriately plan and dimension the network, as well as the back-end cloud systems and the resulting signaling load, traffic models are employed. These models are designed to accurately capture and predict the properties of IoT traffic in a concise manner. To achieve this, Poisson process approximations, based on the Palm–Khintchine theorem, have often been used in the past. Due to the scale (and the difference in scales in various IoT networks) of the modeled systems, the fidelity of this approximation is crucial, as, in practice, it is very challenging to accurately measure or simulate large-scale IoT deployments. The main goal of this paper is to understand the level of accuracy of the Poisson approximation model. To this end, we first survey both common IoT network properties and network scales as well as traffic types. Second, we explain and discuss the Palm–Khintiche theorem, how it is applied to the problem, and which inaccuracies can occur when using it. Based on this, we derive guidelines as to when a Poisson process can be assumed for aggregated periodic IoT traffic. Finally, we evaluate our approach in the context of an IoT cloud scaler use case.
A new QoE fairness index for QoE management Hoßfeld, Tobias; Skorin-Kapov, Lea; Heegaard, Poul E.; Varela, Martin in Quality and User Experience (2018).
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@article{info3-article-2018-2, author = {Hoßfeld, Tobias and Skorin-Kapov, Lea and Heegaard, Poul E. and Varela, Martin}, journal = {Quality and User Experience}, keywords = {sys:hidden:article}, month = 2, title = {A new QoE fairness index for QoE management}, year = 2018 }

%0 Journal Article %1 info3-article-2018-2 %A Hoßfeld, Tobias %A Skorin-Kapov, Lea %A Heegaard, Poul E. %A Varela, Martin %D 2018 %J Quality and User Experience %T A new QoE fairness index for QoE management
A Survey of Emerging Concepts and Challenges for QoE Management of Multimedia Services Skorin-Kapov, Lea; Varela, Martin; Hoßfeld, Tobias; Chen, Kuan-Ta in ACM Transactions on Multimedia Computing, Communications and Applications (2018).
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@article{info3-article-2018-3, author = {Skorin-Kapov, Lea and Varela, Martin and Hoßfeld, Tobias and Chen, Kuan-Ta}, journal = {ACM Transactions on Multimedia Computing, Communications and Applications}, keywords = {sys:hidden:article}, month = 3, title = {A Survey of Emerging Concepts and Challenges for QoE Management of Multimedia Services}, year = 2018 }

%0 Journal Article %1 info3-article-2018-3 %A Skorin-Kapov, Lea %A Varela, Martin %A Hoßfeld, Tobias %A Chen, Kuan-Ta %D 2018 %J ACM Transactions on Multimedia Computing, Communications and Applications %T A Survey of Emerging Concepts and Challenges for QoE Management of Multimedia Services
Active Learning for Crowdsourced QoE Modeling Chang, Haw-Shiuan; Hsu, Chih-Fan; Hoßfeld, Tobias; Chen, Kuan-Ta in IEEE Transactions on Multimedia (2018).
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@article{info3-article-2018-11, author = {Chang, Haw-Shiuan and Hsu, Chih-Fan and Hoßfeld, Tobias and Chen, Kuan-Ta}, journal = {IEEE Transactions on Multimedia}, keywords = {sys:hidden:article}, title = {Active Learning for Crowdsourced QoE Modeling}, year = 2018 }

%0 Journal Article %1 info3-article-2018-11 %A Chang, Haw-Shiuan %A Hsu, Chih-Fan %A Hoßfeld, Tobias %A Chen, Kuan-Ta %D 2018 %J IEEE Transactions on Multimedia %T Active Learning for Crowdsourced QoE Modeling
Quality of experience column: an introduction Hoßfeld, Tobias; Timmerer, Christian in ACM SIGMultimedia Records (2018). (3) 10.
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@article{info3-article-2018-9, author = {Hoßfeld, Tobias and Timmerer, Christian}, journal = {ACM SIGMultimedia Records}, keywords = {sys:hidden:article}, number = 3, pages = 10, title = {Quality of experience column: an introduction}, year = 2018 }

%0 Journal Article %1 info3-article-2018-9 %A Hoßfeld, Tobias %A Timmerer, Christian %D 2018 %J ACM SIGMultimedia Records %N 3 %P 10 %T Quality of experience column: an introduction
Confidence Interval Estimators for MOS Values Hoßfeld, Tobias; Heegaard, Poul E.; Varela, Martin; Skorin-Kapov, Lea in arXiv preprint arXiv:1806.01126 (2018).
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@article{info3-article-2018-10, author = {Hoßfeld, Tobias and Heegaard, Poul E. and Varela, Martin and Skorin-Kapov, Lea}, journal = {arXiv preprint arXiv:1806.01126}, keywords = {sys:hidden:article}, title = {Confidence Interval Estimators for MOS Values}, year = 2018 }

%0 Journal Article %1 info3-article-2018-10 %A Hoßfeld, Tobias %A Heegaard, Poul E. %A Varela, Martin %A Skorin-Kapov, Lea %D 2018 %J arXiv preprint arXiv:1806.01126 %T Confidence Interval Estimators for MOS Values
Impact of VNF Placements on QoE Monitoring in the Cloud Dinh-Xuan, Lam; Popp, Christian; Burger, Valentin; Wamser, Florian; Hoßfeld, Tobias in International Journal of Network Management (2018). (NEM-18-0120.R1)
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@article{info3-article-2018-6, author = {Dinh-Xuan, Lam and Popp, Christian and Burger, Valentin and Wamser, Florian and Hoßfeld, Tobias}, journal = {International Journal of Network Management}, keywords = {video-quality}, month = 10, number = {NEM-18-0120.R1}, title = {Impact of VNF Placements on QoE Monitoring in the Cloud}, year = 2018 }

%0 Journal Article %1 info3-article-2018-6 %A Dinh-Xuan, Lam %A Popp, Christian %A Burger, Valentin %A Wamser, Florian %A Hoßfeld, Tobias %D 2018 %J International Journal of Network Management %N NEM-18-0120.R1 %T Impact of VNF Placements on QoE Monitoring in the Cloud
Guest Editorial: Special Issue on “QoE Management for Multimedia Services” Hoßfeld, Tobias; Skorin-Kapov, Lea; Varela, Martin; Chen, Kuan-Ta in ACM Transactions on Multimedia Computing, Communications, and Applications (TOMM) (2018).
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@article{info3-article-2018-12, author = {Hoßfeld, Tobias and Skorin-Kapov, Lea and Varela, Martin and Chen, Kuan-Ta}, journal = {ACM Transactions on Multimedia Computing, Communications, and Applications (TOMM)}, keywords = {sys:hidden:article}, title = {Guest Editorial: Special Issue on “QoE Management for Multimedia Services”}, year = 2018 }

%0 Journal Article %1 info3-article-2018-12 %A Hoßfeld, Tobias %A Skorin-Kapov, Lea %A Varela, Martin %A Chen, Kuan-Ta %D 2018 %J ACM Transactions on Multimedia Computing, Communications, and Applications (TOMM) %T Guest Editorial: Special Issue on “QoE Management for Multimedia Services”
Towards Machine Learning-Based Optimal HAS Sieber, Christian; Hagn, Korbinian; Moldovan, Christian; Hoßfeld, Tobias; Kellerer, Wolfgang in arXiv preprint arXiv:1808.08065 (2018).
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@article{info3-article-2018-8, author = {Sieber, Christian and Hagn, Korbinian and Moldovan, Christian and Hoßfeld, Tobias and Kellerer, Wolfgang}, journal = {arXiv preprint arXiv:1808.08065}, keywords = {sys:hidden:article}, title = {Towards Machine Learning-Based Optimal HAS}, year = 2018 }

%0 Journal Article %1 info3-article-2018-8 %A Sieber, Christian %A Hagn, Korbinian %A Moldovan, Christian %A Hoßfeld, Tobias %A Kellerer, Wolfgang %D 2018 %J arXiv preprint arXiv:1808.08065 %T Towards Machine Learning-Based Optimal HAS
Softwarization and Caching in NGN Hoßfeld, Tobias; Chan, S-H Gary; Mark, Brian L; Timm-Giel, Andreas in Computer Networks (2017). 125 1–3.
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@article{info3-misc-2017-1, author = {Hoßfeld, Tobias and Chan, S-H Gary and Mark, Brian L and Timm-Giel, Andreas}, journal = {Computer Networks}, keywords = {sys:hidden:article}, month = 10, pages = {1-3}, title = {Softwarization and Caching in NGN}, volume = 125, year = 2017 }

%0 Journal Article %1 info3-misc-2017-1 %A Hoßfeld, Tobias %A Chan, S-H Gary %A Mark, Brian L %A Timm-Giel, Andreas %D 2017 %J Computer Networks %P 1-3 %T Softwarization and Caching in NGN %V 125
2016 International Teletraffic Congress (ITC 28) Report Hoßfeld, Tobias in ACM SIGCOMM Computer Communication Review (2017).
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@article{info3-article-2017-9, author = {Hoßfeld, Tobias}, journal = {ACM SIGCOMM Computer Communication Review}, keywords = {sys:hidden:article}, title = {2016 International Teletraffic Congress (ITC 28) Report}, year = 2017 }

%0 Journal Article %1 info3-article-2017-9 %A Hoßfeld, Tobias %D 2017 %J ACM SIGCOMM Computer Communication Review %T 2016 International Teletraffic Congress (ITC 28) Report
Definition of QoE Fairness in Shared Systems Hoßfeld, Tobias; Skorin-Kapov, Lea; Heegaard, Poul E.; Varela, Martin in IEEE Communications Letters (2016).
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@article{info3-article-2016-11, author = {Hoßfeld, Tobias and Skorin-Kapov, Lea and Heegaard, Poul E. and Varela, Martin}, journal = {IEEE Communications Letters}, keywords = {sys:hidden:article}, title = {Definition of QoE Fairness in Shared Systems}, year = 2016 }

%0 Journal Article %1 info3-article-2016-11 %A Hoßfeld, Tobias %A Skorin-Kapov, Lea %A Heegaard, Poul E. %A Varela, Martin %D 2016 %J IEEE Communications Letters %T Definition of QoE Fairness in Shared Systems
TCP video streaming and mobile networks: Not a love story, but better with context Metzger, Florian; Liotou, Eirini; Moldovan, Christian; Hoßfeld, Tobias in Computer Networks (2016). 109 246–256.
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@article{info3-article-2016-12, author = {Metzger, Florian and Liotou, Eirini and Moldovan, Christian and Hoßfeld, Tobias}, journal = {Computer Networks}, keywords = {sys:hidden:article}, pages = {246–256}, title = {TCP video streaming and mobile networks: Not a love story, but better with context}, volume = 109, year = 2016 }

%0 Journal Article %1 info3-article-2016-12 %A Metzger, Florian %A Liotou, Eirini %A Moldovan, Christian %A Hoßfeld, Tobias %D 2016 %J Computer Networks %P 246--256 %T TCP video streaming and mobile networks: Not a love story, but better with context %V 109
QoE beyond the MOS: an in-depth look at QoE via better metrics and their relation to MOS Hoßfeld, Tobias; Heegaard, Poul E.; Varela, Martin; Möller, Sebastian in Quality and User Experience (2016). 1(2)
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@article{info3-article-2016-10, author = {Hoßfeld, Tobias and Heegaard, Poul E. and Varela, Martin and Möller, Sebastian}, journal = {Quality and User Experience}, keywords = {sys:hidden:article}, number = 2, title = {QoE beyond the MOS: an in-depth look at QoE via better metrics and their relation to MOS}, volume = 1, year = 2016 }

%0 Journal Article %1 info3-article-2016-10 %A Hoßfeld, Tobias %A Heegaard, Poul E. %A Varela, Martin %A Möller, Sebastian %D 2016 %J Quality and User Experience %N 2 %T QoE beyond the MOS: an in-depth look at QoE via better metrics and their relation to MOS %V 1
Modeling the YouTube Stack: from Packets to Quality of Experience Wamser, Florian; Casas, Pedro; Seufert, Michael; Moldovan, Christian; Tran-Gia, Phuoc; Hoßfeld, Tobias in Computer Networks (2016). 109(2) 211–224.
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YouTube is one of the most popular and volume-dominant services in today’s Internet, and has changed the Web for ever. Consequently, network operators are forced to consider it in the design, deployment, and optimization of their networks. Taming YouTube requires a good understanding of the complete YouTube stack, from the network streaming service to the application itself. Understanding the interplays between individual YouTube functionalities and their implications for traffic and user Quality of Experience (QoE) becomes paramount nowadays. In this paper we characterize and model the YouTube stack at different layers, going from the generated network traffic to the QoE perceived by the users watching YouTube videos. Firstly, we present a network traffic model for the YouTube flow control mechanism, which permits to understand how YouTube provisions video traffic flows to users. Secondly, we investigate how traffic is consumed at the client side, deriving a simple model for the YouTube application. Thirdly, we analyze the implications for the end user, and present a model for the quality as perceived by them. This model is finally integrated into a system for real time QoE-based YouTube monitoring, highly useful to operators to assess the performance of their networks for provisioning YouTube videos. The central parameter for all the presented models is the buffer level at the YouTube application layer. This paper provides an extensive compendium of objective tools and models for network operators to better understand the YouTube traffic in their networks, to predict the playback behavior of the video player, and to assess how well they do it in the practice with the satisfaction of their customers watching YouTube.

@article{info3-article-2016-6, abstract = {YouTube is one of the most popular and volume-dominant services in today’s Internet, and has changed the Web for ever. Consequently, network operators are forced to consider it in the design, deployment, and optimization of their networks. Taming YouTube requires a good understanding of the complete YouTube stack, from the network streaming service to the application itself. Understanding the interplays between individual YouTube functionalities and their implications for traffic and user Quality of Experience (QoE) becomes paramount nowadays. In this paper we characterize and model the YouTube stack at different layers, going from the generated network traffic to the QoE perceived by the users watching YouTube videos. Firstly, we present a network traffic model for the YouTube flow control mechanism, which permits to understand how YouTube provisions video traffic flows to users. Secondly, we investigate how traffic is consumed at the client side, deriving a simple model for the YouTube application. Thirdly, we analyze the implications for the end user, and present a model for the quality as perceived by them. This model is finally integrated into a system for real time QoE-based YouTube monitoring, highly useful to operators to assess the performance of their networks for provisioning YouTube videos. The central parameter for all the presented models is the buffer level at the YouTube application layer. This paper provides an extensive compendium of objective tools and models for network operators to better understand the YouTube traffic in their networks, to predict the playback behavior of the video player, and to assess how well they do it in the practice with the satisfaction of their customers watching YouTube.}, author = {Wamser, Florian and Casas, Pedro and Seufert, Michael and Moldovan, Christian and Tran-Gia, Phuoc and Hoßfeld, Tobias}, journal = {Computer Networks}, keywords = {can}, month = 11, number = 2, pages = {211-224}, title = {Modeling the YouTube Stack: from Packets to Quality of Experience}, volume = 109, year = 2016 }

%0 Journal Article %1 info3-article-2016-6 %A Wamser, Florian %A Casas, Pedro %A Seufert, Michael %A Moldovan, Christian %A Tran-Gia, Phuoc %A Hoßfeld, Tobias %D 2016 %J Computer Networks %N 2 %P 211-224 %T Modeling the YouTube Stack: from Packets to Quality of Experience %V 109 %X YouTube is one of the most popular and volume-dominant services in today’s Internet, and has changed the Web for ever. Consequently, network operators are forced to consider it in the design, deployment, and optimization of their networks. Taming YouTube requires a good understanding of the complete YouTube stack, from the network streaming service to the application itself. Understanding the interplays between individual YouTube functionalities and their implications for traffic and user Quality of Experience (QoE) becomes paramount nowadays. In this paper we characterize and model the YouTube stack at different layers, going from the generated network traffic to the QoE perceived by the users watching YouTube videos. Firstly, we present a network traffic model for the YouTube flow control mechanism, which permits to understand how YouTube provisions video traffic flows to users. Secondly, we investigate how traffic is consumed at the client side, deriving a simple model for the YouTube application. Thirdly, we analyze the implications for the end user, and present a model for the quality as perceived by them. This model is finally integrated into a system for real time QoE-based YouTube monitoring, highly useful to operators to assess the performance of their networks for provisioning YouTube videos. The central parameter for all the presented models is the buffer level at the YouTube application layer. This paper provides an extensive compendium of objective tools and models for network operators to better understand the YouTube traffic in their networks, to predict the playback behavior of the video player, and to assess how well they do it in the practice with the satisfaction of their customers watching YouTube.
Performance Evaluation of Backhaul Bandwidth Aggregation Using a Partial Sharing Scheme Burger, Valentin; Seufert, Michael; Hoßfeld, Tobias; Tran-Gia, Phuoc in Physical Communication (2016). 19 135–144.
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To cope with the increasing demand of mobile devices and the limited capacity of cellular networks mobile connections are offloaded to WiFi. The access capacity is further increased, by aggregating bandwidth of WiFi access links. To analyse the performance of aggregated access links we model the most simple case of two cooperating systems interchanging capacities using an offloading scheme. The resulting analytic model is computed by means of a two-dimensional birth and death process. It can be used to seamlessly evaluate the performance of systems between partitioning and complete sharing. This allows to optimize the setting of thresholds dependent on the load of the cooperating system. Furthermore the benefit of aggregating bandwidth in different scenarios with homogeneous and heterogeneous workloads is quantified and the performance of more than two cooperating systems is evaluated by simulation.

@article{info3-article-2016-3, abstract = {To cope with the increasing demand of mobile devices and the limited capacity of cellular networks mobile connections are offloaded to WiFi. The access capacity is further increased, by aggregating bandwidth of WiFi access links. To analyse the performance of aggregated access links we model the most simple case of two cooperating systems interchanging capacities using an offloading scheme. The resulting analytic model is computed by means of a two-dimensional birth and death process. It can be used to seamlessly evaluate the performance of systems between partitioning and complete sharing. This allows to optimize the setting of thresholds dependent on the load of the cooperating system. Furthermore the benefit of aggregating bandwidth in different scenarios with homogeneous and heterogeneous workloads is quantified and the performance of more than two cooperating systems is evaluated by simulation.}, author = {Burger, Valentin and Seufert, Michael and Hoßfeld, Tobias and Tran-Gia, Phuoc}, journal = {Physical Communication}, keywords = {can}, month = 6, pages = {135-144}, title = {Performance Evaluation of Backhaul Bandwidth Aggregation Using a Partial Sharing Scheme}, volume = 19, year = 2016 }

%0 Journal Article %1 info3-article-2016-3 %A Burger, Valentin %A Seufert, Michael %A Hoßfeld, Tobias %A Tran-Gia, Phuoc %D 2016 %J Physical Communication %P 135-144 %T Performance Evaluation of Backhaul Bandwidth Aggregation Using a Partial Sharing Scheme %V 19 %X To cope with the increasing demand of mobile devices and the limited capacity of cellular networks mobile connections are offloaded to WiFi. The access capacity is further increased, by aggregating bandwidth of WiFi access links. To analyse the performance of aggregated access links we model the most simple case of two cooperating systems interchanging capacities using an offloading scheme. The resulting analytic model is computed by means of a two-dimensional birth and death process. It can be used to seamlessly evaluate the performance of systems between partitioning and complete sharing. This allows to optimize the setting of thresholds dependent on the load of the cooperating system. Furthermore the benefit of aggregating bandwidth in different scenarios with homogeneous and heterogeneous workloads is quantified and the performance of more than two cooperating systems is evaluated by simulation.
Formal definition of QoE metrics Hoßfeld, Tobias; Heegaard, Poul E.; Varela, Martin; Möller, Sebastian in arXiv preprint arXiv:1607.00321 (2016).
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@article{info3-article-2016-13, author = {Hoßfeld, Tobias and Heegaard, Poul E. and Varela, Martin and Möller, Sebastian}, journal = {arXiv preprint arXiv:1607.00321}, keywords = {sys:hidden:article}, title = {Formal definition of QoE metrics}, year = 2016 }

%0 Journal Article %1 info3-article-2016-13 %A Hoßfeld, Tobias %A Heegaard, Poul E. %A Varela, Martin %A Möller, Sebastian %D 2016 %J arXiv preprint arXiv:1607.00321 %T Formal definition of QoE metrics
A Simple WiFi Hotspot Model for Cities Seufert, Michael; Griepentrog, Tobias; Burger, Valentin; Hoßfeld, Tobias in IEEE Communications Letters (2016). 20(2) 384–387.
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WiFi offloading has become increasingly popular. Many private and public institutions (e.g., libraries, cafes, restaurants) already provide an alternative free Internet link via WiFi, but also commercial services emerge to mitigate the load on mobile networks. Moreover, smart cities start to establish WiFi infrastructure for current and future civic services. In this work, the hotspot locations of ten diverse large cities are characterized, and a surprisingly simple model for the distribution of WiFi hotspots in an urban environment is derived.

@article{info3-article-2016-2, abstract = {WiFi offloading has become increasingly popular. Many private and public institutions (e.g., libraries, cafes, restaurants) already provide an alternative free Internet link via WiFi, but also commercial services emerge to mitigate the load on mobile networks. Moreover, smart cities start to establish WiFi infrastructure for current and future civic services. In this work, the hotspot locations of ten diverse large cities are characterized, and a surprisingly simple model for the distribution of WiFi hotspots in an urban environment is derived.}, author = {Seufert, Michael and Griepentrog, Tobias and Burger, Valentin and Hoßfeld, Tobias}, journal = {IEEE Communications Letters}, keywords = {can}, month = 2, number = 2, pages = {384 - 387}, title = {A Simple WiFi Hotspot Model for Cities}, volume = 20, year = 2016 }

%0 Journal Article %1 info3-article-2016-2 %A Seufert, Michael %A Griepentrog, Tobias %A Burger, Valentin %A Hoßfeld, Tobias %D 2016 %J IEEE Communications Letters %N 2 %P 384 - 387 %T A Simple WiFi Hotspot Model for Cities %V 20 %X WiFi offloading has become increasingly popular. Many private and public institutions (e.g., libraries, cafes, restaurants) already provide an alternative free Internet link via WiFi, but also commercial services emerge to mitigate the load on mobile networks. Moreover, smart cities start to establish WiFi infrastructure for current and future civic services. In this work, the hotspot locations of ten diverse large cities are characterized, and a surprisingly simple model for the distribution of WiFi hotspots in an urban environment is derived.
More than Topology: Joint Topology and Attribute Sampling and Generation of Social Network Graphs Seufert, Michael; Lange, Stanislav; Hoßfeld, Tobias in Computer Communications (2016). 73(Part B) 176–187.
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Graph sampling refers to the process of deriving a small subset of nodes from a possibly huge graph in order to estimate properties of the whole graph from examining the sample. Whereas topological properties can already be obtained accurately by sampling, current approaches do not take possibly hidden dependencies between node topology and attributes into account. Especially in the context of online social networks, node attributes are of importance as they correspond to properties of the social network's users. Therefore, existing sampling algorithms can be extended to attribute sampling, but still lack the capturing of structural properties. Analyzing topology (e.g., node degree, clustering coefficient) and attribute properties (e.g., age, location) jointly can provide valuable insights into the social network and allows for a better understanding of social processes. As major contribution, this work proposes a novel sampling algorithm which provides unbiased and reliable estimates of joint topological and attribute based graph properties in a resource efficient fashion. Furthermore, the obtained samples allow for the generation of synthetic graphs, which show high similarity to the original graph with respect to topology and attributes. The proposed sampling and generation algorithms are evaluated on real world social network graphs, for which they demonstrate to be effective.

@article{info3-article-2016-1, abstract = {Graph sampling refers to the process of deriving a small subset of nodes from a possibly huge graph in order to estimate properties of the whole graph from examining the sample. Whereas topological properties can already be obtained accurately by sampling, current approaches do not take possibly hidden dependencies between node topology and attributes into account. Especially in the context of online social networks, node attributes are of importance as they correspond to properties of the social network's users. Therefore, existing sampling algorithms can be extended to attribute sampling, but still lack the capturing of structural properties. Analyzing topology (e.g., node degree, clustering coefficient) and attribute properties (e.g., age, location) jointly can provide valuable insights into the social network and allows for a better understanding of social processes. As major contribution, this work proposes a novel sampling algorithm which provides unbiased and reliable estimates of joint topological and attribute based graph properties in a resource efficient fashion. Furthermore, the obtained samples allow for the generation of synthetic graphs, which show high similarity to the original graph with respect to topology and attributes. The proposed sampling and generation algorithms are evaluated on real world social network graphs, for which they demonstrate to be effective.}, author = {Seufert, Michael and Lange, Stanislav and Hoßfeld, Tobias}, journal = {Computer Communications}, keywords = {can}, month = 1, number = {Part B}, pages = {176-187}, title = {More than Topology: Joint Topology and Attribute Sampling and Generation of Social Network Graphs}, volume = 73, year = 2016 }

%0 Journal Article %1 info3-article-2016-1 %A Seufert, Michael %A Lange, Stanislav %A Hoßfeld, Tobias %D 2016 %J Computer Communications %N Part B %P 176-187 %T More than Topology: Joint Topology and Attribute Sampling and Generation of Social Network Graphs %V 73 %X Graph sampling refers to the process of deriving a small subset of nodes from a possibly huge graph in order to estimate properties of the whole graph from examining the sample. Whereas topological properties can already be obtained accurately by sampling, current approaches do not take possibly hidden dependencies between node topology and attributes into account. Especially in the context of online social networks, node attributes are of importance as they correspond to properties of the social network's users. Therefore, existing sampling algorithms can be extended to attribute sampling, but still lack the capturing of structural properties. Analyzing topology (e.g., node degree, clustering coefficient) and attribute properties (e.g., age, location) jointly can provide valuable insights into the social network and allows for a better understanding of social processes. As major contribution, this work proposes a novel sampling algorithm which provides unbiased and reliable estimates of joint topological and attribute based graph properties in a resource efficient fashion. Furthermore, the obtained samples allow for the generation of synthetic graphs, which show high similarity to the original graph with respect to topology and attributes. The proposed sampling and generation algorithms are evaluated on real world social network graphs, for which they demonstrate to be effective.
Identifying QoE Optimal Adaptation of HTTP Adaptive Streaming Based on Subjective Studies Hoßfeld, Tobias; Seufert, Michael; Sieber, Christian; Zinner, Thomas; Tran-Gia, Phuoc in Computer Networks (2015). 81 320–332.
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HTTP Adaptive Streaming (HAS) technologies, e.g., Apple HLS or MPEG-DASH, automatically adapt the delivered video quality to the available network. This reduces stalling of the video but additionally introduces quality switches, which also influence the user-perceived Quality of Experience (QoE). In this work, we conduct a subjective study to identify the impact of adaptation parameters on QoE. The results indicate that the video quality has to be maximized first, and that the number of quality switches is less important. Based on these results, a method to compute the optimal QoE-optimal adaptation strategy for HAS on a per user basis with mixed-integer linear programming is presented. This QoE-optimal adaptation enables the benchmarking of existing adaptation algorithms for any given network condition. Moreover, the investigated concept is extended to a multi-user IPTV scenario. The question is answered whether video quality, and thereby, the QoE can be shared in a fair manner among the involved users.

@article{info3-article-2015-132, abstract = {HTTP Adaptive Streaming (HAS) technologies, e.g., Apple HLS or MPEG-DASH, automatically adapt the delivered video quality to the available network. This reduces stalling of the video but additionally introduces quality switches, which also influence the user-perceived Quality of Experience (QoE). In this work, we conduct a subjective study to identify the impact of adaptation parameters on QoE. The results indicate that the video quality has to be maximized first, and that the number of quality switches is less important. Based on these results, a method to compute the optimal QoE-optimal adaptation strategy for HAS on a per user basis with mixed-integer linear programming is presented. This QoE-optimal adaptation enables the benchmarking of existing adaptation algorithms for any given network condition. Moreover, the investigated concept is extended to a multi-user IPTV scenario. The question is answered whether video quality, and thereby, the QoE can be shared in a fair manner among the involved users.}, author = {Hoßfeld, Tobias and Seufert, Michael and Sieber, Christian and Zinner, Thomas and Tran-Gia, Phuoc}, journal = {Computer Networks}, keywords = {sys:hidden:article}, month = 4, pages = {320-332}, title = {Identifying QoE Optimal Adaptation of HTTP Adaptive Streaming Based on Subjective Studies}, volume = 81, year = 2015 }

%0 Journal Article %1 info3-article-2015-132 %A Hoßfeld, Tobias %A Seufert, Michael %A Sieber, Christian %A Zinner, Thomas %A Tran-Gia, Phuoc %D 2015 %J Computer Networks %P 320-332 %T Identifying QoE Optimal Adaptation of HTTP Adaptive Streaming Based on Subjective Studies %V 81 %X HTTP Adaptive Streaming (HAS) technologies, e.g., Apple HLS or MPEG-DASH, automatically adapt the delivered video quality to the available network. This reduces stalling of the video but additionally introduces quality switches, which also influence the user-perceived Quality of Experience (QoE). In this work, we conduct a subjective study to identify the impact of adaptation parameters on QoE. The results indicate that the video quality has to be maximized first, and that the number of quality switches is less important. Based on these results, a method to compute the optimal QoE-optimal adaptation strategy for HAS on a per user basis with mixed-integer linear programming is presented. This QoE-optimal adaptation enables the benchmarking of existing adaptation algorithms for any given network condition. Moreover, the investigated concept is extended to a multi-user IPTV scenario. The question is answered whether video quality, and thereby, the QoE can be shared in a fair manner among the involved users.
A Survey on Quality of Experience of HTTP Adaptive Streaming Seufert, Michael; Egger, Sebastian; Slanina, Martin; Zinner, Thomas; Hoßfeld, Tobias; Tran-Gia, Phuoc in IEEE Communications Surveys & Tutorials (2015). 17 469–492.
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Changing network conditions pose severe problems to video streaming in the Internet. HTTP adaptive streaming (HAS) is a technology employed by numerous video services which relieves these issues by adapting the video to the current network conditions. It enables service providers to improve resource utilization and Quality of Experience (QoE) by incorporating information from different layers in order to deliver and adapt a video in its best possible quality. Thereby, it allows to take into account end user device capabilities, available video quality levels, current network conditions, and current server load. For end users, the major benefits of HAS compared to classical HTTP video streaming are reduced interruptions of the video playback and higher bandwidth utilization, which both generally result in a higher QoE. Adaptation is possible by changing the frame rate, resolution, or quantization of the video, which can be done with various adaptation strategies and related client- and server-side actions. The technical development of HAS, existing open standardized solutions, but also proprietary solutions are reviewed in this article as fundament to derive the QoE influence factors which emerge as a result of adaptation. The main contribution is a comprehensive survey of QoE related works from human computer interaction and networking domains which are structured according to the QoE impact of video adaptation. To be more precise, subjective studies which cover QoE aspects of adaptation dimensions and strategies are revisited. As a result, QoE influence factors of HAS and corresponding QoE models are identified, but also open issues and conflicting results are discussed. Furthermore, technical influence factors, which are often ignored in the context of HAS, affect perceptual QoE influence factors and are consequently analyzed. This survey gives the reader an overview of the current state of the art and recent developments. At the same time it targets networking researchers who develop new solutions for HTTP video streaming or assess video streaming from a user centric point of view. Therefore, the article is a major step towards truly improving HAS.

@article{info3-article-2015-126, abstract = {Changing network conditions pose severe problems to video streaming in the Internet. HTTP adaptive streaming (HAS) is a technology employed by numerous video services which relieves these issues by adapting the video to the current network conditions. It enables service providers to improve resource utilization and Quality of Experience (QoE) by incorporating information from different layers in order to deliver and adapt a video in its best possible quality. Thereby, it allows to take into account end user device capabilities, available video quality levels, current network conditions, and current server load. For end users, the major benefits of HAS compared to classical HTTP video streaming are reduced interruptions of the video playback and higher bandwidth utilization, which both generally result in a higher QoE. Adaptation is possible by changing the frame rate, resolution, or quantization of the video, which can be done with various adaptation strategies and related client- and server-side actions. The technical development of HAS, existing open standardized solutions, but also proprietary solutions are reviewed in this article as fundament to derive the QoE influence factors which emerge as a result of adaptation. The main contribution is a comprehensive survey of QoE related works from human computer interaction and networking domains which are structured according to the QoE impact of video adaptation. To be more precise, subjective studies which cover QoE aspects of adaptation dimensions and strategies are revisited. As a result, QoE influence factors of HAS and corresponding QoE models are identified, but also open issues and conflicting results are discussed. Furthermore, technical influence factors, which are often ignored in the context of HAS, affect perceptual QoE influence factors and are consequently analyzed. This survey gives the reader an overview of the current state of the art and recent developments. At the same time it targets networking researchers who develop new solutions for HTTP video streaming or assess video streaming from a user centric point of view. Therefore, the article is a major step towards truly improving HAS.}, author = {Seufert, Michael and Egger, Sebastian and Slanina, Martin and Zinner, Thomas and Hoßfeld, Tobias and Tran-Gia, Phuoc}, journal = {IEEE Communications Surveys & Tutorials}, keywords = {sys:hidden:article}, month = 3, pages = {469-492}, title = {A Survey on Quality of Experience of HTTP Adaptive Streaming}, volume = 17, year = 2015 }

%0 Journal Article %1 info3-article-2015-126 %A Seufert, Michael %A Egger, Sebastian %A Slanina, Martin %A Zinner, Thomas %A Hoßfeld, Tobias %A Tran-Gia, Phuoc %D 2015 %J IEEE Communications Surveys & Tutorials %P 469-492 %T A Survey on Quality of Experience of HTTP Adaptive Streaming %V 17 %X Changing network conditions pose severe problems to video streaming in the Internet. HTTP adaptive streaming (HAS) is a technology employed by numerous video services which relieves these issues by adapting the video to the current network conditions. It enables service providers to improve resource utilization and Quality of Experience (QoE) by incorporating information from different layers in order to deliver and adapt a video in its best possible quality. Thereby, it allows to take into account end user device capabilities, available video quality levels, current network conditions, and current server load. For end users, the major benefits of HAS compared to classical HTTP video streaming are reduced interruptions of the video playback and higher bandwidth utilization, which both generally result in a higher QoE. Adaptation is possible by changing the frame rate, resolution, or quantization of the video, which can be done with various adaptation strategies and related client- and server-side actions. The technical development of HAS, existing open standardized solutions, but also proprietary solutions are reviewed in this article as fundament to derive the QoE influence factors which emerge as a result of adaptation. The main contribution is a comprehensive survey of QoE related works from human computer interaction and networking domains which are structured according to the QoE impact of video adaptation. To be more precise, subjective studies which cover QoE aspects of adaptation dimensions and strategies are revisited. As a result, QoE influence factors of HAS and corresponding QoE models are identified, but also open issues and conflicting results are discussed. Furthermore, technical influence factors, which are often ignored in the context of HAS, affect perceptual QoE influence factors and are consequently analyzed. This survey gives the reader an overview of the current state of the art and recent developments. At the same time it targets networking researchers who develop new solutions for HTTP video streaming or assess video streaming from a user centric point of view. Therefore, the article is a major step towards truly improving HAS.
Crowdsourced Network Measurements: Benefits and Best Practices Hirth, Matthias; Hoßfeld, Tobias; Mellia, Marco; Schwartz, Christian; Lehrieder, Frank in Computer Networks Special Issue on Crowdsourcing (2015).
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Network measurements are of high importance both for the operation of networks and for the design and evaluation of new management mechanisms. Therefore, several approaches exist for running network measurements, ranging from analyzing live traffic traces from campus or Internet Service Provider (ISP) networks to performing active measurements on distributed testbeds, e.g., PlanetLab, or involving volunteers. However, each method falls short, offering only a partial view of the network. For instance, the scope of passive traffic traces is limited to an ISP’s network and customers’ habits, whereas active measurements might be biased by the population or node location involved. To complement these techniques, we pro- pose to use (commercial) crowdsourcing platforms for network measurements. They permit a controllable, diverse and realistic view of the Internet and pro- vide better control than do measurements with voluntary participants. In this study, we compare crowdsourcing with traditional measurement techniques, describe possible pitfalls and limitations, and present best practices to overcome these issues. The contribution of this paper is a guideline for researchers to understand when and how to exploit crowdsourcing for network measurements.

@article{info3-article-2015-135, abstract = {Network measurements are of high importance both for the operation of networks and for the design and evaluation of new management mechanisms. Therefore, several approaches exist for running network measurements, ranging from analyzing live traffic traces from campus or Internet Service Provider (ISP) networks to performing active measurements on distributed testbeds, e.g., PlanetLab, or involving volunteers. However, each method falls short, offering only a partial view of the network. For instance, the scope of passive traffic traces is limited to an ISP’s network and customers’ habits, whereas active measurements might be biased by the population or node location involved. To complement these techniques, we pro- pose to use (commercial) crowdsourcing platforms for network measurements. They permit a controllable, diverse and realistic view of the Internet and pro- vide better control than do measurements with voluntary participants. In this study, we compare crowdsourcing with traditional measurement techniques, describe possible pitfalls and limitations, and present best practices to overcome these issues. The contribution of this paper is a guideline for researchers to understand when and how to exploit crowdsourcing for network measurements.}, author = {Hirth, Matthias and Hoßfeld, Tobias and Mellia, Marco and Schwartz, Christian and Lehrieder, Frank}, journal = {Computer Networks Special Issue on Crowdsourcing}, keywords = {sys:hidden:article}, title = {Crowdsourced Network Measurements: Benefits and Best Practices}, year = 2015 }

%0 Journal Article %1 info3-article-2015-135 %A Hirth, Matthias %A Hoßfeld, Tobias %A Mellia, Marco %A Schwartz, Christian %A Lehrieder, Frank %D 2015 %J Computer Networks Special Issue on Crowdsourcing %T Crowdsourced Network Measurements: Benefits and Best Practices %X Network measurements are of high importance both for the operation of networks and for the design and evaluation of new management mechanisms. Therefore, several approaches exist for running network measurements, ranging from analyzing live traffic traces from campus or Internet Service Provider (ISP) networks to performing active measurements on distributed testbeds, e.g., PlanetLab, or involving volunteers. However, each method falls short, offering only a partial view of the network. For instance, the scope of passive traffic traces is limited to an ISP’s network and customers’ habits, whereas active measurements might be biased by the population or node location involved. To complement these techniques, we pro- pose to use (commercial) crowdsourcing platforms for network measurements. They permit a controllable, diverse and realistic view of the Internet and pro- vide better control than do measurements with voluntary participants. In this study, we compare crowdsourcing with traditional measurement techniques, describe possible pitfalls and limitations, and present best practices to overcome these issues. The contribution of this paper is a guideline for researchers to understand when and how to exploit crowdsourcing for network measurements.
QoE for Cloud Gaming Hoßfeld, Tobias; Metzger, Florian; Jarschel, Michael in IEEE Communications Society E-Letter (2015).
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Cloud Gaming combines the successful concepts of Cloud Computing and Online Gaming. It provides the entire game experience to the users by processing the game in the cloud and streaming the contents to the player. The player is no longer dependent on a specific type or quality of gaming hardware, but is able to use common devices. However, at the same time the end device needs a broadband internet connection and the ability to display a video stream properly. While this may reduce hardware costs for users and increase the revenue for developers by leaving out the retail chain, it also raises new challenges for Quality of Service (QoS) in terms of bandwidth and latency for the underlying network. In particular, there is a strong interest in the player’s Quality of Experience (QoE) by the involved stakeholders, ie, the game providers and the network operators. Given similar pricing schemes, players are likely to be influenced by expected and experienced quality. Thus, a provider is interested to understand QoE and to react on QoE problems by managing or adapting the service. There is also a strong academic interest, since QoE for cloud gaming as well as managing QoE for cloud gaming addresses a multitude of fascinating challenges in QoE. One might think that the topic of online video games is equally popular in research, but efforts are often solely focused on cloud gaming and its subjective QoE through user studies. Compared to plain video streaming, the inner properties of video games are not that straight-forward to observe from the outside. But to conduct proper measurements, it is essential to understand them.

@article{info3-article-2015-9, abstract = {Cloud Gaming combines the successful concepts of Cloud Computing and Online Gaming. It provides the entire game experience to the users by processing the game in the cloud and streaming the contents to the player. The player is no longer dependent on a specific type or quality of gaming hardware, but is able to use common devices. However, at the same time the end device needs a broadband internet connection and the ability to display a video stream properly. While this may reduce hardware costs for users and increase the revenue for developers by leaving out the retail chain, it also raises new challenges for Quality of Service (QoS) in terms of bandwidth and latency for the underlying network. In particular, there is a strong interest in the player’s Quality of Experience (QoE) by the involved stakeholders, ie, the game providers and the network operators. Given similar pricing schemes, players are likely to be influenced by expected and experienced quality. Thus, a provider is interested to understand QoE and to react on QoE problems by managing or adapting the service. There is also a strong academic interest, since QoE for cloud gaming as well as managing QoE for cloud gaming addresses a multitude of fascinating challenges in QoE. One might think that the topic of online video games is equally popular in research, but efforts are often solely focused on cloud gaming and its subjective QoE through user studies. Compared to plain video streaming, the inner properties of video games are not that straight-forward to observe from the outside. But to conduct proper measurements, it is essential to understand them.}, author = {Hoßfeld, Tobias and Metzger, Florian and Jarschel, Michael}, journal = {IEEE Communications Society E-Letter}, keywords = {sys:hidden:article}, month = 11, title = {QoE for Cloud Gaming}, year = 2015 }

%0 Journal Article %1 info3-article-2015-9 %A Hoßfeld, Tobias %A Metzger, Florian %A Jarschel, Michael %D 2015 %J IEEE Communications Society E-Letter %T QoE for Cloud Gaming %X Cloud Gaming combines the successful concepts of Cloud Computing and Online Gaming. It provides the entire game experience to the users by processing the game in the cloud and streaming the contents to the player. The player is no longer dependent on a specific type or quality of gaming hardware, but is able to use common devices. However, at the same time the end device needs a broadband internet connection and the ability to display a video stream properly. While this may reduce hardware costs for users and increase the revenue for developers by leaving out the retail chain, it also raises new challenges for Quality of Service (QoS) in terms of bandwidth and latency for the underlying network. In particular, there is a strong interest in the player’s Quality of Experience (QoE) by the involved stakeholders, ie, the game providers and the network operators. Given similar pricing schemes, players are likely to be influenced by expected and experienced quality. Thus, a provider is interested to understand QoE and to react on QoE problems by managing or adapting the service. There is also a strong academic interest, since QoE for cloud gaming as well as managing QoE for cloud gaming addresses a multitude of fascinating challenges in QoE. One might think that the topic of online video games is equally popular in research, but efforts are often solely focused on cloud gaming and its subjective QoE through user studies. Compared to plain video streaming, the inner properties of video games are not that straight-forward to observe from the outside. But to conduct proper measurements, it is essential to understand them.
Special issue on crowdsourcing Hoßfeld, Tobias; Tran-Gia, Phuoc; Vukovic, Maja in Computer Networks: The International Journal of Computer and Telecommunications Networking (2015).
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@article{info3-article-2015-10, author = {Hoßfeld, Tobias and Tran-Gia, Phuoc and Vukovic, Maja}, journal = {Computer Networks: The International Journal of Computer and Telecommunications Networking}, keywords = {sys:hidden:article}, title = {Special issue on crowdsourcing}, year = 2015 }

%0 Journal Article %1 info3-article-2015-10 %A Hoßfeld, Tobias %A Tran-Gia, Phuoc %A Vukovic, Maja %D 2015 %J Computer Networks: The International Journal of Computer and Telecommunications Networking %T Special issue on crowdsourcing
On Training the Crowd for Subjective Quality Studies Hoßfeld, Tobias in VQEG eLetter (2014). 1
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“On Training the Crowd for Subjective Quality Studies” by Tobias Hossfeld from University of Würzburg presents new possibilities for quality evaluation by conducting subjective studies with the crowd of Internet users. The challenges of conducting training sessions for different methods of crowd sourcing are also elaborated in the article. The eLetter is online at the <a href='http://www.its.bldrdoc.gov/vqeg/eletter.aspx'>Video Quality Experts Group (VQEG) homepage</a>.

@article{info3-article-2014-120, abstract = {“On Training the Crowd for Subjective Quality Studies” by Tobias Hossfeld from University of Würzburg presents new possibilities for quality evaluation by conducting subjective studies with the crowd of Internet users. The challenges of conducting training sessions for different methods of crowd sourcing are also elaborated in the article. The eLetter is online at the <a href='http://www.its.bldrdoc.gov/vqeg/eletter.aspx'>Video Quality Experts Group (VQEG) homepage</a>.}, author = {Hoßfeld, Tobias}, journal = {VQEG eLetter}, keywords = {sys:hidden:article}, month = 3, title = {On Training the Crowd for Subjective Quality Studies}, volume = 1, year = 2014 }

%0 Journal Article %1 info3-article-2014-120 %A Hoßfeld, Tobias %D 2014 %J VQEG eLetter %T On Training the Crowd for Subjective Quality Studies %V 1 %X “On Training the Crowd for Subjective Quality Studies” by Tobias Hossfeld from University of Würzburg presents new possibilities for quality evaluation by conducting subjective studies with the crowd of Internet users. The challenges of conducting training sessions for different methods of crowd sourcing are also elaborated in the article. The eLetter is online at the <a href='http://www.its.bldrdoc.gov/vqeg/eletter.aspx'>Video Quality Experts Group (VQEG) homepage</a>.
Requirement Driven Prospects for Realizing User-Centric Network Orchestration Zinner, Thomas; Hoßfeld, Tobias; Fiedler, Markus; Liers, Florian; Volkert, Thomas; Khondoker, Rahamatullah; Schatz, Raimund in Multimedia Tools and Applications (2014).
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The Internet’s infrastructure shows severe limitations when an optimal end user experience for multimedia applications should be achieved in a resource-efficiently way. In order to realize truly user-centric networking, an information exchange between applications and networks is required. To this end, network-application interfaces need to be deployed that enable a better mediation of application data through the Internet. For smart multimedia applications and services, the application and the network should directly communicate with each other and exchange information in order to ensure an optimal Quality of Experience (QoE). In this article, we follow a use-case driven approach towards user-centric network orchestration. We derive user, application, and network requirements for three complementary use cases: HD live TV streaming, video-on-demand streaming and user authentication with high security and privacy demands, as typically required for payed multimedia services. We provide practical guidelines for achieving an optimal QoE efficiently in the context of these use cases. Based on these results, we demonstrate how to overcome one of the main limitations of today’s Internet by introducing the major steps required for user-centric network orchestration. Finally, we show conceptual prospects for realizing these steps by discussing a possible implementation with an inter-network architecture based on functional blocks.

@article{info3-article-2014-122, abstract = {The Internet’s infrastructure shows severe limitations when an optimal end user experience for multimedia applications should be achieved in a resource-efficiently way. In order to realize truly user-centric networking, an information exchange between applications and networks is required. To this end, network-application interfaces need to be deployed that enable a better mediation of application data through the Internet. For smart multimedia applications and services, the application and the network should directly communicate with each other and exchange information in order to ensure an optimal Quality of Experience (QoE). In this article, we follow a use-case driven approach towards user-centric network orchestration. We derive user, application, and network requirements for three complementary use cases: HD live TV streaming, video-on-demand streaming and user authentication with high security and privacy demands, as typically required for payed multimedia services. We provide practical guidelines for achieving an optimal QoE efficiently in the context of these use cases. Based on these results, we demonstrate how to overcome one of the main limitations of today’s Internet by introducing the major steps required for user-centric network orchestration. Finally, we show conceptual prospects for realizing these steps by discussing a possible implementation with an inter-network architecture based on functional blocks.}, author = {Zinner, Thomas and Hoßfeld, Tobias and Fiedler, Markus and Liers, Florian and Volkert, Thomas and Khondoker, Rahamatullah and Schatz, Raimund}, journal = {Multimedia Tools and Applications}, keywords = {sys:hidden:article}, month = 6, title = {Requirement Driven Prospects for Realizing User-Centric Network Orchestration}, year = 2014 }

%0 Journal Article %1 info3-article-2014-122 %A Zinner, Thomas %A Hoßfeld, Tobias %A Fiedler, Markus %A Liers, Florian %A Volkert, Thomas %A Khondoker, Rahamatullah %A Schatz, Raimund %D 2014 %J Multimedia Tools and Applications %T Requirement Driven Prospects for Realizing User-Centric Network Orchestration %X The Internet’s infrastructure shows severe limitations when an optimal end user experience for multimedia applications should be achieved in a resource-efficiently way. In order to realize truly user-centric networking, an information exchange between applications and networks is required. To this end, network-application interfaces need to be deployed that enable a better mediation of application data through the Internet. For smart multimedia applications and services, the application and the network should directly communicate with each other and exchange information in order to ensure an optimal Quality of Experience (QoE). In this article, we follow a use-case driven approach towards user-centric network orchestration. We derive user, application, and network requirements for three complementary use cases: HD live TV streaming, video-on-demand streaming and user authentication with high security and privacy demands, as typically required for payed multimedia services. We provide practical guidelines for achieving an optimal QoE efficiently in the context of these use cases. Based on these results, we demonstrate how to overcome one of the main limitations of today’s Internet by introducing the major steps required for user-centric network orchestration. Finally, we show conceptual prospects for realizing these steps by discussing a possible implementation with an inter-network architecture based on functional blocks.
Close to Optimum? User-centric Evaluation of Adaptation Logics for HTTP Adaptive Streaming Hoßfeld, Tobias; Seufert, Michael; Sieber, Christian; Zinner, Thomas; Tran-Gia, Phuoc in PIK - Praxis der Informationsverarbeitung und Kommunikation (2014). 37 275–285.
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HTTP Adaptive Streaming (HAS) is the de-facto standard for over-the-top (OTT) video streaming services. It allows to react to fluctuating network conditions on short time scales by adapting the video bit rate in order to avoid stalling of the video playback. With HAS the video content is split into small segments of a few seconds playtime each, which are available in different bit rates, i.e., quality level representations. Depending on the current conditions, the adaptation algorithm on the client side chooses the appropriate quality level and downloads the respective segment. This allows to avoid stalling, which is seen as the worst possible disturbance of HTTP video streaming, to the most possible extend. Nevertheless, the user perceived Quality of Experience (QoE) may be affected, namely by playing back lower qualities and by switching between different qualities. Therefore, adaptation algorithms are desired which maximize the user’sQoEfor the currently available network resources. Many downloading strategies have been proposed in literature, but a solid user-centric comparison of these mechanisms among each other and with the global optimum is missing. The major contributions of this work are as follows. A proper analysis of the influence of quality switches and played out representations on QoE is conducted by means of subjective user studies. The results suggest that, in order to optimize QoE, first, the quality level of the video stream has to be maximized and second, the number of quality switches should be minimized. Based on our findings, a QoEoptimization problem is formulated and the performance of our proposed algorithm is compared to other algorithms and to the QoE-optimal adaptation.

@article{info3-article-2014-127, abstract = {HTTP Adaptive Streaming (HAS) is the de-facto standard for over-the-top (OTT) video streaming services. It allows to react to fluctuating network conditions on short time scales by adapting the video bit rate in order to avoid stalling of the video playback. With HAS the video content is split into small segments of a few seconds playtime each, which are available in different bit rates, i.e., quality level representations. Depending on the current conditions, the adaptation algorithm on the client side chooses the appropriate quality level and downloads the respective segment. This allows to avoid stalling, which is seen as the worst possible disturbance of HTTP video streaming, to the most possible extend. Nevertheless, the user perceived Quality of Experience (QoE) may be affected, namely by playing back lower qualities and by switching between different qualities. Therefore, adaptation algorithms are desired which maximize the user’sQoEfor the currently available network resources. Many downloading strategies have been proposed in literature, but a solid user-centric comparison of these mechanisms among each other and with the global optimum is missing. The major contributions of this work are as follows. A proper analysis of the influence of quality switches and played out representations on QoE is conducted by means of subjective user studies. The results suggest that, in order to optimize QoE, first, the quality level of the video stream has to be maximized and second, the number of quality switches should be minimized. Based on our findings, a QoEoptimization problem is formulated and the performance of our proposed algorithm is compared to other algorithms and to the QoE-optimal adaptation.}, author = {Hoßfeld, Tobias and Seufert, Michael and Sieber, Christian and Zinner, Thomas and Tran-Gia, Phuoc}, journal = {PIK - Praxis der Informationsverarbeitung und Kommunikation}, keywords = {sys:hidden:article}, month = 10, pages = {275-285}, title = {Close to Optimum? User-centric Evaluation of Adaptation Logics for HTTP Adaptive Streaming}, volume = 37, year = 2014 }

%0 Journal Article %1 info3-article-2014-127 %A Hoßfeld, Tobias %A Seufert, Michael %A Sieber, Christian %A Zinner, Thomas %A Tran-Gia, Phuoc %D 2014 %J PIK - Praxis der Informationsverarbeitung und Kommunikation %P 275-285 %T Close to Optimum? User-centric Evaluation of Adaptation Logics for HTTP Adaptive Streaming %V 37 %X HTTP Adaptive Streaming (HAS) is the de-facto standard for over-the-top (OTT) video streaming services. It allows to react to fluctuating network conditions on short time scales by adapting the video bit rate in order to avoid stalling of the video playback. With HAS the video content is split into small segments of a few seconds playtime each, which are available in different bit rates, i.e., quality level representations. Depending on the current conditions, the adaptation algorithm on the client side chooses the appropriate quality level and downloads the respective segment. This allows to avoid stalling, which is seen as the worst possible disturbance of HTTP video streaming, to the most possible extend. Nevertheless, the user perceived Quality of Experience (QoE) may be affected, namely by playing back lower qualities and by switching between different qualities. Therefore, adaptation algorithms are desired which maximize the user’sQoEfor the currently available network resources. Many downloading strategies have been proposed in literature, but a solid user-centric comparison of these mechanisms among each other and with the global optimum is missing. The major contributions of this work are as follows. A proper analysis of the influence of quality switches and played out representations on QoE is conducted by means of subjective user studies. The results suggest that, in order to optimize QoE, first, the quality level of the video stream has to be maximized and second, the number of quality switches should be minimized. Based on our findings, a QoEoptimization problem is formulated and the performance of our proposed algorithm is compared to other algorithms and to the QoE-optimal adaptation.
Best Practices for QoE Crowdtesting: QoE Assessment with Crowdsourcing Hoßfeld, Tobias; Keimel, Christian; Hirth, Matthias; Gardlo, Bruno; Habigt, Julian; Diepold, Klaus; Tran-Gia, Phuoc in Transactions on Multimedia (2014). 16
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Quality of Experience (QoE) in multimedia applications is closely linked to the end users’ perception and therefore its assessment requires subjective user studies in order to evaluate the degree of delight or annoyance as experienced by the users. QoE crowdtesting refers to QoE assessment using crowdsourcing, where anonymous test subjects conduct subjective tests remotely in their preferred environment. The advantages of QoE crowdtesting lie not only in the reduced time and costs for the tests, but also in a large and diverse panel of international, geographically distributed users in realistic user settings. However, conceptual and technical challenges emerge due to the remote test settings. Key issues arising from QoE crowdtesting include the reliability of user ratings, the influence of incentives, payment schemes and the unknown environmental context of the tests on the results. In order to counter these issues, strategies and methods need to be developed, included in the test design, and also implemented in the actual test campaign, while statistical methods are required to identify reliable user ratings and to ensure high data quality. This contribution therefore provides a collection of best practices addressing these issues based on our experience gained in a large set of conducted QoE crowdtesting studies. The focus of this article is in particular on the issue of reliability and we use video quality assessment as an example for the proposed best practices, showing that our recommended two-stage QoE crowdtesting design leads to more reliable results.

@article{info3-article-2014-117, abstract = {Quality of Experience (QoE) in multimedia applications is closely linked to the end users’ perception and therefore its assessment requires subjective user studies in order to evaluate the degree of delight or annoyance as experienced by the users. QoE crowdtesting refers to QoE assessment using crowdsourcing, where anonymous test subjects conduct subjective tests remotely in their preferred environment. The advantages of QoE crowdtesting lie not only in the reduced time and costs for the tests, but also in a large and diverse panel of international, geographically distributed users in realistic user settings. However, conceptual and technical challenges emerge due to the remote test settings. Key issues arising from QoE crowdtesting include the reliability of user ratings, the influence of incentives, payment schemes and the unknown environmental context of the tests on the results. In order to counter these issues, strategies and methods need to be developed, included in the test design, and also implemented in the actual test campaign, while statistical methods are required to identify reliable user ratings and to ensure high data quality. This contribution therefore provides a collection of best practices addressing these issues based on our experience gained in a large set of conducted QoE crowdtesting studies. The focus of this article is in particular on the issue of reliability and we use video quality assessment as an example for the proposed best practices, showing that our recommended two-stage QoE crowdtesting design leads to more reliable results.}, author = {Hoßfeld, Tobias and Keimel, Christian and Hirth, Matthias and Gardlo, Bruno and Habigt, Julian and Diepold, Klaus and Tran-Gia, Phuoc}, journal = {Transactions on Multimedia}, keywords = {sys:hidden:article}, month = 2, title = {Best Practices for QoE Crowdtesting: QoE Assessment with Crowdsourcing}, volume = 16, year = 2014 }

%0 Journal Article %1 info3-article-2014-117 %A Hoßfeld, Tobias %A Keimel, Christian %A Hirth, Matthias %A Gardlo, Bruno %A Habigt, Julian %A Diepold, Klaus %A Tran-Gia, Phuoc %D 2014 %J Transactions on Multimedia %T Best Practices for QoE Crowdtesting: QoE Assessment with Crowdsourcing %V 16 %X Quality of Experience (QoE) in multimedia applications is closely linked to the end users’ perception and therefore its assessment requires subjective user studies in order to evaluate the degree of delight or annoyance as experienced by the users. QoE crowdtesting refers to QoE assessment using crowdsourcing, where anonymous test subjects conduct subjective tests remotely in their preferred environment. The advantages of QoE crowdtesting lie not only in the reduced time and costs for the tests, but also in a large and diverse panel of international, geographically distributed users in realistic user settings. However, conceptual and technical challenges emerge due to the remote test settings. Key issues arising from QoE crowdtesting include the reliability of user ratings, the influence of incentives, payment schemes and the unknown environmental context of the tests on the results. In order to counter these issues, strategies and methods need to be developed, included in the test design, and also implemented in the actual test campaign, while statistical methods are required to identify reliable user ratings and to ensure high data quality. This contribution therefore provides a collection of best practices addressing these issues based on our experience gained in a large set of conducted QoE crowdtesting studies. The focus of this article is in particular on the issue of reliability and we use video quality assessment as an example for the proposed best practices, showing that our recommended two-stage QoE crowdtesting design leads to more reliable results.
Crowdsourcing Quality-of-Experience Assessments Hoßfeld, Tobias; Keimel, Christian; Timmerer, Christian in IEEE Computer (2014). 47 98–102.
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Crowdsourced quality-of-experience (QoE) assessments are more costeffective and flexible than traditional in-lab evaluations but require careful test design, innovative incentive mechanisms, and technical expertise to address various implementation challenges.

@article{info3-article-2014-129, abstract = {Crowdsourced quality-of-experience (QoE) assessments are more costeffective and flexible than traditional in-lab evaluations but require careful test design, innovative incentive mechanisms, and technical expertise to address various implementation challenges.}, author = {Hoßfeld, Tobias and Keimel, Christian and Timmerer, Christian}, journal = {IEEE Computer}, keywords = {sys:hidden:article}, month = 9, pages = {98-102}, title = {Crowdsourcing Quality-of-Experience Assessments}, volume = 47, year = 2014 }

%0 Journal Article %1 info3-article-2014-129 %A Hoßfeld, Tobias %A Keimel, Christian %A Timmerer, Christian %D 2014 %J IEEE Computer %P 98-102 %T Crowdsourcing Quality-of-Experience Assessments %V 47 %X Crowdsourced quality-of-experience (QoE) assessments are more costeffective and flexible than traditional in-lab evaluations but require careful test design, innovative incentive mechanisms, and technical expertise to address various implementation challenges.
Quality of Experience Assessment using Crowdsourcing Hoßfeld, Tobias; Timmerer, Christian in IEEE COMSOC MMTC R-Letter (2014). 5
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A short review for the article 'Best Practices for QoE Crowdtesting: QoE Assessment with Crowdsourcing' Edited by Tobias Hoßfeld and Christian Timmerer Online at: http://committees.comsoc.org/mmc/r-letters/MMTC-RLetter-Jun2014.pdf Tobias Hoßfeld, Christian Keimel, Matthias Hirth, Bruno Gardlo, Julian Habigt, Klaus Diepold, Phuoc Tran-Gia, 'Best Practices for QoE Crowdtesting: QoE Assessment with Crowdsourcing', IEEE Trans. on Multimedia, vol. 16, no. 2, pp. 541–558, Feb. 2014.

@article{info3-article-2014-125, abstract = {A short review for the article 'Best Practices for QoE Crowdtesting: QoE Assessment with Crowdsourcing' Edited by Tobias Hoßfeld and Christian Timmerer Online at: http://committees.comsoc.org/mmc/r-letters/MMTC-RLetter-Jun2014.pdf Tobias Hoßfeld, Christian Keimel, Matthias Hirth, Bruno Gardlo, Julian Habigt, Klaus Diepold, Phuoc Tran-Gia, 'Best Practices for QoE Crowdtesting: QoE Assessment with Crowdsourcing', IEEE Trans. on Multimedia, vol. 16, no. 2, pp. 541–558, Feb. 2014.}, author = {Hoßfeld, Tobias and Timmerer, Christian}, journal = {IEEE COMSOC MMTC R-Letter}, keywords = {sys:hidden:article}, month = 6, title = {Quality of Experience Assessment using Crowdsourcing}, volume = 5, year = 2014 }

%0 Journal Article %1 info3-article-2014-125 %A Hoßfeld, Tobias %A Timmerer, Christian %D 2014 %J IEEE COMSOC MMTC R-Letter %T Quality of Experience Assessment using Crowdsourcing %V 5 %X A short review for the article 'Best Practices for QoE Crowdtesting: QoE Assessment with Crowdsourcing' Edited by Tobias Hoßfeld and Christian Timmerer Online at: http://committees.comsoc.org/mmc/r-letters/MMTC-RLetter-Jun2014.pdf Tobias Hoßfeld, Christian Keimel, Matthias Hirth, Bruno Gardlo, Julian Habigt, Klaus Diepold, Phuoc Tran-Gia, 'Best Practices for QoE Crowdtesting: QoE Assessment with Crowdsourcing', IEEE Trans. on Multimedia, vol. 16, no. 2, pp. 541–558, Feb. 2014.
Interfaces, Attributes, and Use Cases: A Compass for SDN Jarschel, Michael; Zinner, Thomas; Hoßfeld, Tobias; Tran-Gia, Phuoc; Kellerer, Wolfgang in IEEE Communications Magazine (2014). 52 210–217.
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The term Software Defined Networking (SDN) is prevalent in today’s discussion about future communication networks. As with any new term or paradigm, however, no consistent definition regarding this technology has formed. The fragmented view on SDN results in legacy products being passed off by equipment vendors as SDN, academics mixing up the attributes of SDN with those of network virtualization, and users not fully understanding the benefits. Therefore, establishing SDN as a widely adopted technology beyond laboratories and insular deployments requires a compass to navigate the multitude of ideas and concepts that make up SDN today. The contribution of this article represents an important step toward such an instrument. It gives a thorough definition of SDN and its interfaces as well as a list of its key attributes. Furthermore, a mapping of interfaces and attributes to SDN use cases is provided, highlighting the relevance of the interfaces and attributes for each scenario. This compass gives guidance to a potential adopter of SDN on whether SDN is in fact the right technology for a specific use case.

@article{info3-article-2014-124, abstract = {The term Software Defined Networking (SDN) is prevalent in today’s discussion about future communication networks. As with any new term or paradigm, however, no consistent definition regarding this technology has formed. The fragmented view on SDN results in legacy products being passed off by equipment vendors as SDN, academics mixing up the attributes of SDN with those of network virtualization, and users not fully understanding the benefits. Therefore, establishing SDN as a widely adopted technology beyond laboratories and insular deployments requires a compass to navigate the multitude of ideas and concepts that make up SDN today. The contribution of this article represents an important step toward such an instrument. It gives a thorough definition of SDN and its interfaces as well as a list of its key attributes. Furthermore, a mapping of interfaces and attributes to SDN use cases is provided, highlighting the relevance of the interfaces and attributes for each scenario. This compass gives guidance to a potential adopter of SDN on whether SDN is in fact the right technology for a specific use case.}, author = {Jarschel, Michael and Zinner, Thomas and Hoßfeld, Tobias and Tran-Gia, Phuoc and Kellerer, Wolfgang}, journal = {IEEE Communications Magazine}, keywords = {sys:hidden:article}, month = 6, pages = {210-217}, title = {Interfaces, Attributes, and Use Cases: A Compass for SDN}, volume = 52, year = 2014 }

%0 Journal Article %1 info3-article-2014-124 %A Jarschel, Michael %A Zinner, Thomas %A Hoßfeld, Tobias %A Tran-Gia, Phuoc %A Kellerer, Wolfgang %D 2014 %J IEEE Communications Magazine %P 210-217 %T Interfaces, Attributes, and Use Cases: A Compass for SDN %V 52 %X The term Software Defined Networking (SDN) is prevalent in today’s discussion about future communication networks. As with any new term or paradigm, however, no consistent definition regarding this technology has formed. The fragmented view on SDN results in legacy products being passed off by equipment vendors as SDN, academics mixing up the attributes of SDN with those of network virtualization, and users not fully understanding the benefits. Therefore, establishing SDN as a widely adopted technology beyond laboratories and insular deployments requires a compass to navigate the multitude of ideas and concepts that make up SDN today. The contribution of this article represents an important step toward such an instrument. It gives a thorough definition of SDN and its interfaces as well as a list of its key attributes. Furthermore, a mapping of interfaces and attributes to SDN use cases is provided, highlighting the relevance of the interfaces and attributes for each scenario. This compass gives guidance to a potential adopter of SDN on whether SDN is in fact the right technology for a specific use case.
On the computation of entropy production in stationary social networks Hoßfeld, Tobias; Burger, Valentin; Hinrichsen, Haye; Hirth, Matthias; Tran-Gia, Phuoc in Social Network Analysis and Mining (2014). 4
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Completing their initial phase of rapid growth, social networks are expected to reach a plateau from where on they are in a statistically stationary state. Such stationary conditions may have different dynamical properties. For example, if each message in a network is followed by a reply in opposite direction, the dynamics is locally balanced. Otherwise, if messages are ignored or forwarded to a different user, one may reach a stationary state with a directed flow of information. To distinguish between the two situations, we propose a quantity called entropy production that was introduced in statistical physics as a measure for non-vanishing probability currents in nonequilibrium stationary states. The proposed quantity closes a gap for characterizing online social networks. As major contribution, we show the relation and difference between entropy production and existing metrics. The comparison shows that computational intensive metrics like centrality can be approximated by entropy production for typical online social networks. To compute the entropy production from real-world measurements, the need for Bayesian inference and the limits of naïve estimates for those probability currents are shown. As further contribution, a general scheme is presented to measure the entropy production in small-world networks using Bayesian inference. The scheme is then applied for a specific example of the R mailing list.

@article{info3-article-2014-123, abstract = {Completing their initial phase of rapid growth, social networks are expected to reach a plateau from where on they are in a statistically stationary state. Such stationary conditions may have different dynamical properties. For example, if each message in a network is followed by a reply in opposite direction, the dynamics is locally balanced. Otherwise, if messages are ignored or forwarded to a different user, one may reach a stationary state with a directed flow of information. To distinguish between the two situations, we propose a quantity called entropy production that was introduced in statistical physics as a measure for non-vanishing probability currents in nonequilibrium stationary states. The proposed quantity closes a gap for characterizing online social networks. As major contribution, we show the relation and difference between entropy production and existing metrics. The comparison shows that computational intensive metrics like centrality can be approximated by entropy production for typical online social networks. To compute the entropy production from real-world measurements, the need for Bayesian inference and the limits of naïve estimates for those probability currents are shown. As further contribution, a general scheme is presented to measure the entropy production in small-world networks using Bayesian inference. The scheme is then applied for a specific example of the R mailing list.}, author = {Hoßfeld, Tobias and Burger, Valentin and Hinrichsen, Haye and Hirth, Matthias and Tran-Gia, Phuoc}, journal = {Social Network Analysis and Mining}, keywords = {sys:hidden:article}, month = 4, title = {On the computation of entropy production in stationary social networks}, volume = 4, year = 2014 }

%0 Journal Article %1 info3-article-2014-123 %A Hoßfeld, Tobias %A Burger, Valentin %A Hinrichsen, Haye %A Hirth, Matthias %A Tran-Gia, Phuoc %D 2014 %J Social Network Analysis and Mining %T On the computation of entropy production in stationary social networks %V 4 %X Completing their initial phase of rapid growth, social networks are expected to reach a plateau from where on they are in a statistically stationary state. Such stationary conditions may have different dynamical properties. For example, if each message in a network is followed by a reply in opposite direction, the dynamics is locally balanced. Otherwise, if messages are ignored or forwarded to a different user, one may reach a stationary state with a directed flow of information. To distinguish between the two situations, we propose a quantity called entropy production that was introduced in statistical physics as a measure for non-vanishing probability currents in nonequilibrium stationary states. The proposed quantity closes a gap for characterizing online social networks. As major contribution, we show the relation and difference between entropy production and existing metrics. The comparison shows that computational intensive metrics like centrality can be approximated by entropy production for typical online social networks. To compute the entropy production from real-world measurements, the need for Bayesian inference and the limits of naïve estimates for those probability currents are shown. As further contribution, a general scheme is presented to measure the entropy production in small-world networks using Bayesian inference. The scheme is then applied for a specific example of the R mailing list.
Angry Apps: The Impact of Network Timer Selection on Power Consumption, Signalling Load, and Web QoE Schwartz, Christian; Hoßfeld, Tobias; Lehrieder, Frank; Tran-Gia, Phuoc in Journal of Computer Networks and Communications (2013). 1–22.
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The popularity of smartphones and mobile applications has experienced a considerable growth during recent years and this growth is expected to continue in the future. Since smartphones have only very limited energy resources, battery efficiency is one of the deter- mining factors for a good user experience. Therefore, some smartphones tear down connec- tions to the mobile network soon after a completed data transmission to reduce the power consumption of their transmission unit. However, frequent connection re-establishments caused by apps which send or receive small amounts of data often lead to a heavy signalling load within the mobile network. One of the major contributions of this article is the investigation of the resulting trade-off between energy consumption at the smartphone and the generated signalling traffic in the mobile network. We explain that this trade-off can be controlled by the connection release timeout and study the impact of this parameter for a number of popular apps that cover a wide range of traffic characteristics in terms of bandwidth requirements and resulting signalling traffic. Finally, we study the impact of the timer settings on QoE for web traffic. This is an important aspect since connection establishments do not only lead to signalling traffic, but they also increase the load time of web pages.

@article{info3-article-2013-108, abstract = {The popularity of smartphones and mobile applications has experienced a considerable growth during recent years and this growth is expected to continue in the future. Since smartphones have only very limited energy resources, battery efficiency is one of the deter- mining factors for a good user experience. Therefore, some smartphones tear down connec- tions to the mobile network soon after a completed data transmission to reduce the power consumption of their transmission unit. However, frequent connection re-establishments caused by apps which send or receive small amounts of data often lead to a heavy signalling load within the mobile network. One of the major contributions of this article is the investigation of the resulting trade-off between energy consumption at the smartphone and the generated signalling traffic in the mobile network. We explain that this trade-off can be controlled by the connection release timeout and study the impact of this parameter for a number of popular apps that cover a wide range of traffic characteristics in terms of bandwidth requirements and resulting signalling traffic. Finally, we study the impact of the timer settings on QoE for web traffic. This is an important aspect since connection establishments do not only lead to signalling traffic, but they also increase the load time of web pages.}, author = {Schwartz, Christian and Hoßfeld, Tobias and Lehrieder, Frank and Tran-Gia, Phuoc}, journal = {Journal of Computer Networks and Communications}, keywords = {sys:hidden:article}, month = 9, pages = {1 - 22}, title = {Angry Apps: The Impact of Network Timer Selection on Power Consumption, Signalling Load, and Web QoE}, year = 2013 }

%0 Journal Article %1 info3-article-2013-108 %A Schwartz, Christian %A Hoßfeld, Tobias %A Lehrieder, Frank %A Tran-Gia, Phuoc %D 2013 %J Journal of Computer Networks and Communications %P 1 - 22 %T Angry Apps: The Impact of Network Timer Selection on Power Consumption, Signalling Load, and Web QoE %X The popularity of smartphones and mobile applications has experienced a considerable growth during recent years and this growth is expected to continue in the future. Since smartphones have only very limited energy resources, battery efficiency is one of the deter- mining factors for a good user experience. Therefore, some smartphones tear down connec- tions to the mobile network soon after a completed data transmission to reduce the power consumption of their transmission unit. However, frequent connection re-establishments caused by apps which send or receive small amounts of data often lead to a heavy signalling load within the mobile network. One of the major contributions of this article is the investigation of the resulting trade-off between energy consumption at the smartphone and the generated signalling traffic in the mobile network. We explain that this trade-off can be controlled by the connection release timeout and study the impact of this parameter for a number of popular apps that cover a wide range of traffic characteristics in terms of bandwidth requirements and resulting signalling traffic. Finally, we study the impact of the timer settings on QoE for web traffic. This is an important aspect since connection establishments do not only lead to signalling traffic, but they also increase the load time of web pages.
Crowdsourcing and its Impact on Future Internet Usage Tran-Gia, Phuoc; Hoßfeld, Tobias; Hartmann, Matthias; Hirth, Matthias in it - Information Technology (2013). 55 139–145.
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Crowdsourcing is an emerging service platform and business model in the Internet. In contrast to outsourcing where a job is performed by a designated contractor, with Crowdsourcing, jobs are outsourced to a large, anonymous crowd of workers, the so-called human cloud. The rise of Crowdsourcing and its seamless integration in current workflows may have a huge impact on the Internet and on society, and will be a guiding paradigm that can form the evolution of work in the years to come. In this article, we discuss applications and use cases of Crowdsourcing to demonstrate the impact on Internet usage. Novel measurement approaches are presented and the impact of Crowdsourcing on Internet traffic is evaluated by measuring the activity of a particular Crowdsourcing platform. New technical solutions are necessary for the operation of efficient, distributed Crowdsourcing platforms. Special attention is drawn to the integration of machine clouds and human crowds, and appropriate inter-cloud solutions. Finally, we discuss current research challenges from a scientific and from the platform provider’s point of view.

@article{info3-article-2013-113, abstract = {Crowdsourcing is an emerging service platform and business model in the Internet. In contrast to outsourcing where a job is performed by a designated contractor, with Crowdsourcing, jobs are outsourced to a large, anonymous crowd of workers, the so-called human cloud. The rise of Crowdsourcing and its seamless integration in current workflows may have a huge impact on the Internet and on society, and will be a guiding paradigm that can form the evolution of work in the years to come. In this article, we discuss applications and use cases of Crowdsourcing to demonstrate the impact on Internet usage. Novel measurement approaches are presented and the impact of Crowdsourcing on Internet traffic is evaluated by measuring the activity of a particular Crowdsourcing platform. New technical solutions are necessary for the operation of efficient, distributed Crowdsourcing platforms. Special attention is drawn to the integration of machine clouds and human crowds, and appropriate inter-cloud solutions. Finally, we discuss current research challenges from a scientific and from the platform provider’s point of view.}, author = {Tran-Gia, Phuoc and Hoßfeld, Tobias and Hartmann, Matthias and Hirth, Matthias}, journal = {it - Information Technology}, keywords = {sys:hidden:article}, month = 7, pages = {139-145}, title = {Crowdsourcing and its Impact on Future Internet Usage}, volume = 55, year = 2013 }

%0 Journal Article %1 info3-article-2013-113 %A Tran-Gia, Phuoc %A Hoßfeld, Tobias %A Hartmann, Matthias %A Hirth, Matthias %D 2013 %J it - Information Technology %P 139-145 %T Crowdsourcing and its Impact on Future Internet Usage %V 55 %X Crowdsourcing is an emerging service platform and business model in the Internet. In contrast to outsourcing where a job is performed by a designated contractor, with Crowdsourcing, jobs are outsourced to a large, anonymous crowd of workers, the so-called human cloud. The rise of Crowdsourcing and its seamless integration in current workflows may have a huge impact on the Internet and on society, and will be a guiding paradigm that can form the evolution of work in the years to come. In this article, we discuss applications and use cases of Crowdsourcing to demonstrate the impact on Internet usage. Novel measurement approaches are presented and the impact of Crowdsourcing on Internet traffic is evaluated by measuring the activity of a particular Crowdsourcing platform. New technical solutions are necessary for the operation of efficient, distributed Crowdsourcing platforms. Special attention is drawn to the integration of machine clouds and human crowds, and appropriate inter-cloud solutions. Finally, we discuss current research challenges from a scientific and from the platform provider’s point of view.
Crowdsourcing - Modell einer neuen Arbeitswelt im Internet Hoßfeld, Tobias; Hirth, Matthias; Tran-Gia, Phuoc in Informatik Spektrum, Wirtschaftsinformatik & Management (2013). 5
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Das Internet hat bereits viele höchst erfolgreiche Geschäftsmodelle hervorgebracht. Jedoch basierten bisher die meisten neuen Anwendungen oder Dienstleistungen auf technischen Neuerungen, beispielsweise schnelleren Rechner, kürzeren Verbindungsdauern oder auf neuartigen algorithmischen Ansätzen, etwa der Page-Rank-Algorithmus von Google. Erst mit den Sozialen Medien wie Youtube oder Facebook wurden die Nutzer ein integraler Bestandteil der Wertschöpfungskette, ohne die das „Produkt“ nicht funktioniert. Einen ähnlich starken Einfluss auf den Erfolg eines Unternehmens haben Nutzer in Geschäftsmodellen, die auf dem Crowdsourcing-Paradigma beruhen, welches im Folgenden genauer beleuchtet werden soll.

@article{info3-article-2013-116, abstract = {Das Internet hat bereits viele höchst erfolgreiche Geschäftsmodelle hervorgebracht. Jedoch basierten bisher die meisten neuen Anwendungen oder Dienstleistungen auf technischen Neuerungen, beispielsweise schnelleren Rechner, kürzeren Verbindungsdauern oder auf neuartigen algorithmischen Ansätzen, etwa der Page-Rank-Algorithmus von Google. Erst mit den Sozialen Medien wie Youtube oder Facebook wurden die Nutzer ein integraler Bestandteil der Wertschöpfungskette, ohne die das „Produkt“ nicht funktioniert. Einen ähnlich starken Einfluss auf den Erfolg eines Unternehmens haben Nutzer in Geschäftsmodellen, die auf dem Crowdsourcing-Paradigma beruhen, welches im Folgenden genauer beleuchtet werden soll.}, author = {Hoßfeld, Tobias and Hirth, Matthias and Tran-Gia, Phuoc}, journal = {Informatik Spektrum, Wirtschaftsinformatik & Management}, keywords = {sys:hidden:article}, month = 10, title = {Crowdsourcing - Modell einer neuen Arbeitswelt im Internet}, volume = 5, year = 2013 }

%0 Journal Article %1 info3-article-2013-116 %A Hoßfeld, Tobias %A Hirth, Matthias %A Tran-Gia, Phuoc %D 2013 %J Informatik Spektrum, Wirtschaftsinformatik & Management %T Crowdsourcing - Modell einer neuen Arbeitswelt im Internet %V 5 %X Das Internet hat bereits viele höchst erfolgreiche Geschäftsmodelle hervorgebracht. Jedoch basierten bisher die meisten neuen Anwendungen oder Dienstleistungen auf technischen Neuerungen, beispielsweise schnelleren Rechner, kürzeren Verbindungsdauern oder auf neuartigen algorithmischen Ansätzen, etwa der Page-Rank-Algorithmus von Google. Erst mit den Sozialen Medien wie Youtube oder Facebook wurden die Nutzer ein integraler Bestandteil der Wertschöpfungskette, ohne die das „Produkt“ nicht funktioniert. Einen ähnlich starken Einfluss auf den Erfolg eines Unternehmens haben Nutzer in Geschäftsmodellen, die auf dem Crowdsourcing-Paradigma beruhen, welches im Folgenden genauer beleuchtet werden soll.
Software defined Networks - Das Internet flexibler gestalten und dynamischer steuern Zinner, Thomas; Hoßfeld, Tobias; Tran-Gia, Phuoc; Kellerer, Wolfgang in ITG Mitgliederbeilage / VDE dialog (invited article) (2013). 6–9.
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Vor allem aufgrund seiner starren Architektur und mangelnden Ressourcennutzung ist die Flexibilität der aktuellen Internettechnologie eingeschränkt. Dies könnte sich durch Anwendung von Software Defined Networks (SDN) ändern. Hierbei wird die Steuerung der Netze und Datenflüsse von den bisherigen Netzkomponenten auf eine zentrale logische Einheit übertragen.

@article{info3-article-2013-115, abstract = {Vor allem aufgrund seiner starren Architektur und mangelnden Ressourcennutzung ist die Flexibilität der aktuellen Internettechnologie eingeschränkt. Dies könnte sich durch Anwendung von Software Defined Networks (SDN) ändern. Hierbei wird die Steuerung der Netze und Datenflüsse von den bisherigen Netzkomponenten auf eine zentrale logische Einheit übertragen.}, author = {Zinner, Thomas and Hoßfeld, Tobias and Tran-Gia, Phuoc and Kellerer, Wolfgang}, journal = {ITG Mitgliederbeilage / VDE dialog (invited article)}, keywords = {sys:hidden:article}, month = 10, pages = {6-9}, title = {Software defined Networks - Das Internet flexibler gestalten und dynamischer steuern}, year = 2013 }

%0 Journal Article %1 info3-article-2013-115 %A Zinner, Thomas %A Hoßfeld, Tobias %A Tran-Gia, Phuoc %A Kellerer, Wolfgang %D 2013 %J ITG Mitgliederbeilage / VDE dialog (invited article) %P 6-9 %T Software defined Networks - Das Internet flexibler gestalten und dynamischer steuern %X Vor allem aufgrund seiner starren Architektur und mangelnden Ressourcennutzung ist die Flexibilität der aktuellen Internettechnologie eingeschränkt. Dies könnte sich durch Anwendung von Software Defined Networks (SDN) ändern. Hierbei wird die Steuerung der Netze und Datenflüsse von den bisherigen Netzkomponenten auf eine zentrale logische Einheit übertragen.
Caching for BitTorrent-like P2P Systems: A Simple Fluid Model and its Implications Lehrieder, Frank; Dán, György; Hoßfeld, Tobias; Oechsner, Simon; Singeorzan, Vlad in IEEE/ACM Transactions on Networking (2012). 20(4)
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Peer-to-peer file-sharing systems are responsible for a significant share of the traffic between Internet service providers (ISPs) in the Internet. In order to decrease their peer-to-peer-related transit traffic costs, many ISPs have deployed caches for peer-to-peer traffic in recent years. We consider how the different types of peer-to-peer caches—caches already available on the market and caches expected to become available in the future—can possibly affect the amount of inter-ISP traffic. We develop a fluid model that captures the effects of the caches on the system dynamics of peer-to-peer networks and show that caches can have adverse effects on the system dynamics depending on the system parameters. We combine the fluid model with a simple model of inter-ISP traffic and show that the impact of caches cannot be accurately assessed without considering the effects of the caches on the system dynamics. We identify scenarios when caching actually leads to increased transit traffic. Motivated by our findings, we propose a proximity-aware peer-selection mechanism that avoids the increase of the transit traffic and improves the cache efficiency.We support the analytical results by extensive simulations and experiments with real BitTorrent clients.

@article{info3-article-2012-94, abstract = {Peer-to-peer file-sharing systems are responsible for a significant share of the traffic between Internet service providers (ISPs) in the Internet. In order to decrease their peer-to-peer-related transit traffic costs, many ISPs have deployed caches for peer-to-peer traffic in recent years. We consider how the different types of peer-to-peer caches—caches already available on the market and caches expected to become available in the future—can possibly affect the amount of inter-ISP traffic. We develop a fluid model that captures the effects of the caches on the system dynamics of peer-to-peer networks and show that caches can have adverse effects on the system dynamics depending on the system parameters. We combine the fluid model with a simple model of inter-ISP traffic and show that the impact of caches cannot be accurately assessed without considering the effects of the caches on the system dynamics. We identify scenarios when caching actually leads to increased transit traffic. Motivated by our findings, we propose a proximity-aware peer-selection mechanism that avoids the increase of the transit traffic and improves the cache efficiency.We support the analytical results by extensive simulations and experiments with real BitTorrent clients.}, author = {Lehrieder, Frank and Dán, György and Hoßfeld, Tobias and Oechsner, Simon and Singeorzan, Vlad}, journal = {IEEE/ACM Transactions on Networking}, keywords = {sys:hidden:article}, title = {Caching for BitTorrent-like P2P Systems: A Simple Fluid Model and its Implications}, volume = {20(4)}, year = 2012 }

%0 Journal Article %1 info3-article-2012-94 %A Lehrieder, Frank %A Dán, György %A Hoßfeld, Tobias %A Oechsner, Simon %A Singeorzan, Vlad %D 2012 %J IEEE/ACM Transactions on Networking %T Caching for BitTorrent-like P2P Systems: A Simple Fluid Model and its Implications %V 20(4) %X Peer-to-peer file-sharing systems are responsible for a significant share of the traffic between Internet service providers (ISPs) in the Internet. In order to decrease their peer-to-peer-related transit traffic costs, many ISPs have deployed caches for peer-to-peer traffic in recent years. We consider how the different types of peer-to-peer caches—caches already available on the market and caches expected to become available in the future—can possibly affect the amount of inter-ISP traffic. We develop a fluid model that captures the effects of the caches on the system dynamics of peer-to-peer networks and show that caches can have adverse effects on the system dynamics depending on the system parameters. We combine the fluid model with a simple model of inter-ISP traffic and show that the impact of caches cannot be accurately assessed without considering the effects of the caches on the system dynamics. We identify scenarios when caching actually leads to increased transit traffic. Motivated by our findings, we propose a proximity-aware peer-selection mechanism that avoids the increase of the transit traffic and improves the cache efficiency.We support the analytical results by extensive simulations and experiments with real BitTorrent clients.
Analyzing Costs and Accuracy of Validation Mechanisms for Crowdsourcing Platforms Hirth, Matthias; Hoßfeld, Tobias; Tran-Gia, Phuoc in Mathematical and Computer Modelling (2012).
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Crowdsourcing is becoming more and more important for commercial purposes. With the growth of crowdsourcing platforms like Amazon Mechanical Turk or Microworkers, a huge work force and a large knowledge base can be easily accessed and utilized. But due to the anonymity of the workers, they are encouraged to cheat the employers in order to maximize their income. Thus, this paper we analyze two widely used crowd-based approaches to validate the submitted work. Both approaches are evaluated with regard to their detection quality, their costs and their applicability to different types of typical crowdsourcing tasks

@article{info3-article-2012-96, abstract = {Crowdsourcing is becoming more and more important for commercial purposes. With the growth of crowdsourcing platforms like Amazon Mechanical Turk or Microworkers, a huge work force and a large knowledge base can be easily accessed and utilized. But due to the anonymity of the workers, they are encouraged to cheat the employers in order to maximize their income. Thus, this paper we analyze two widely used crowd-based approaches to validate the submitted work. Both approaches are evaluated with regard to their detection quality, their costs and their applicability to different types of typical crowdsourcing tasks}, author = {Hirth, Matthias and Hoßfeld, Tobias and Tran-Gia, Phuoc}, journal = {Mathematical and Computer Modelling}, keywords = {sys:hidden:article}, title = {Analyzing Costs and Accuracy of Validation Mechanisms for Crowdsourcing Platforms}, year = 2012 }

%0 Journal Article %1 info3-article-2012-96 %A Hirth, Matthias %A Hoßfeld, Tobias %A Tran-Gia, Phuoc %D 2012 %J Mathematical and Computer Modelling %T Analyzing Costs and Accuracy of Validation Mechanisms for Crowdsourcing Platforms %X Crowdsourcing is becoming more and more important for commercial purposes. With the growth of crowdsourcing platforms like Amazon Mechanical Turk or Microworkers, a huge work force and a large knowledge base can be easily accessed and utilized. But due to the anonymity of the workers, they are encouraged to cheat the employers in order to maximize their income. Thus, this paper we analyze two widely used crowd-based approaches to validate the submitted work. Both approaches are evaluated with regard to their detection quality, their costs and their applicability to different types of typical crowdsourcing tasks
The Network of Excellence Euro-NF and its Specific Joint Research Projects Fiedler, Markus; Hoßfeld, Tobias; Norros, Ilkka; Rodrigues, Joel; Rogério Pereira, Paulo in ICST Global Community Magazine (2012).
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This article presents the European FP7 Network of Excellence “Euro-NF” (Networks of the Future) and reviews its set of activities. Specific attention is paid to the concept of Specific Joint Research Projects (SJRP), a series of small but focused projects, integrating at least three Euro-NF partners and targeting joint seminal work, publications as well as full-size follow-up projects. Further to the description of the SJRP concept, a set of three selected SJRP from different areas are presented in detail with respect to motivation, goal, contents, results, and impact.

@article{info3-article-2012-98, abstract = {This article presents the European FP7 Network of Excellence “Euro-NF” (Networks of the Future) and reviews its set of activities. Specific attention is paid to the concept of Specific Joint Research Projects (SJRP), a series of small but focused projects, integrating at least three Euro-NF partners and targeting joint seminal work, publications as well as full-size follow-up projects. Further to the description of the SJRP concept, a set of three selected SJRP from different areas are presented in detail with respect to motivation, goal, contents, results, and impact.}, author = {Fiedler, Markus and Hoßfeld, Tobias and Norros, Ilkka and Rodrigues, Joel and Rogério Pereira, Paulo}, journal = {ICST Global Community Magazine}, keywords = {sys:hidden:article}, title = {The Network of Excellence Euro-NF and its Specific Joint Research Projects}, year = 2012 }

%0 Journal Article %1 info3-article-2012-98 %A Fiedler, Markus %A Hoßfeld, Tobias %A Norros, Ilkka %A Rodrigues, Joel %A Rogério Pereira, Paulo %D 2012 %J ICST Global Community Magazine %T The Network of Excellence Euro-NF and its Specific Joint Research Projects %X This article presents the European FP7 Network of Excellence “Euro-NF” (Networks of the Future) and reviews its set of activities. Specific attention is paid to the concept of Specific Joint Research Projects (SJRP), a series of small but focused projects, integrating at least three Euro-NF partners and targeting joint seminal work, publications as well as full-size follow-up projects. Further to the description of the SJRP concept, a set of three selected SJRP from different areas are presented in detail with respect to motivation, goal, contents, results, and impact.
Challenges of QoE Management for Cloud Applications Hoßfeld, Tobias; Schatz, Raimund; Varela, Martin; Timmerer, Christian in IEEE Communications Magazine (2012). April issue
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Cloud computing is currently gaining enormous momentum due to a number of promised benefits: ease of use in terms of deployment, administration and maintenance, high scalability and flexibility to create new services. However, as more personal and business applications migrate to the Cloud, the service quality will become an important differentiator between providers. In particular, Quality of Experience (QoE) as perceived by users has the potential become the guiding paradigm for managing quality in the Cloud. In this article, we discuss technical challenges emerging from shifting services to the Cloud, as well as how this shift impacts QoE and QoE management. Thereby, a particular focus is on multimedia Cloud applications. Together with a novel QoE-based classification scheme of cloud applications, these challenges drive the research agenda on QoE management for Cloud applications.

@article{info3-article-2012-97, abstract = {Cloud computing is currently gaining enormous momentum due to a number of promised benefits: ease of use in terms of deployment, administration and maintenance, high scalability and flexibility to create new services. However, as more personal and business applications migrate to the Cloud, the service quality will become an important differentiator between providers. In particular, Quality of Experience (QoE) as perceived by users has the potential become the guiding paradigm for managing quality in the Cloud. In this article, we discuss technical challenges emerging from shifting services to the Cloud, as well as how this shift impacts QoE and QoE management. Thereby, a particular focus is on multimedia Cloud applications. Together with a novel QoE-based classification scheme of cloud applications, these challenges drive the research agenda on QoE management for Cloud applications.}, author = {Hoßfeld, Tobias and Schatz, Raimund and Varela, Martin and Timmerer, Christian}, journal = {IEEE Communications Magazine}, keywords = {sys:hidden:article}, month = 4, title = {Challenges of QoE Management for Cloud Applications}, volume = {April issue}, year = 2012 }

%0 Journal Article %1 info3-article-2012-97 %A Hoßfeld, Tobias %A Schatz, Raimund %A Varela, Martin %A Timmerer, Christian %D 2012 %J IEEE Communications Magazine %T Challenges of QoE Management for Cloud Applications %V April issue %X Cloud computing is currently gaining enormous momentum due to a number of promised benefits: ease of use in terms of deployment, administration and maintenance, high scalability and flexibility to create new services. However, as more personal and business applications migrate to the Cloud, the service quality will become an important differentiator between providers. In particular, Quality of Experience (QoE) as perceived by users has the potential become the guiding paradigm for managing quality in the Cloud. In this article, we discuss technical challenges emerging from shifting services to the Cloud, as well as how this shift impacts QoE and QoE management. Thereby, a particular focus is on multimedia Cloud applications. Together with a novel QoE-based classification scheme of cloud applications, these challenges drive the research agenda on QoE management for Cloud applications.
Gaming in the clouds: QoE and the users’ perspective Jarschel, Michael; Schlosser, Daniel; Scheuring, Sven; Hoßfeld, Tobias in Mathematical and Computer Modelling (2012).
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Cloud Gaming is a new kind of service, which combines the successful concepts of Cloud Computing and Online Gaming. It provides the entire game experience to the users remotely from a data center. The player is no longer dependent on a specific type or quality of gaming hardware, but is able to use common devices. The end device only needs a broadband internet connection and the ability to display High Definition (HD) video. While this may reduce hardware costs for users and increase the revenue for developers by leaving out the retail chain, it also raises new challenges for service quality in terms of bandwidth and latency for the underlying network. In this paper we present the results of a subjective user study we conducted into the user-perceived quality of experience (QoE) in Cloud Gaming. We design a measurement environment, that emulates this new type of service, define tests for users to assess the QoE, derive Key Influence Factors (KFI) and influences of content and perception from our results.

@article{info3-article-2012-95, abstract = {Cloud Gaming is a new kind of service, which combines the successful concepts of Cloud Computing and Online Gaming. It provides the entire game experience to the users remotely from a data center. The player is no longer dependent on a specific type or quality of gaming hardware, but is able to use common devices. The end device only needs a broadband internet connection and the ability to display High Definition (HD) video. While this may reduce hardware costs for users and increase the revenue for developers by leaving out the retail chain, it also raises new challenges for service quality in terms of bandwidth and latency for the underlying network. In this paper we present the results of a subjective user study we conducted into the user-perceived quality of experience (QoE) in Cloud Gaming. We design a measurement environment, that emulates this new type of service, define tests for users to assess the QoE, derive Key Influence Factors (KFI) and influences of content and perception from our results.}, author = {Jarschel, Michael and Schlosser, Daniel and Scheuring, Sven and Hoßfeld, Tobias}, journal = {Mathematical and Computer Modelling}, keywords = {sys:hidden:article}, title = {Gaming in the clouds: QoE and the users’ perspective}, year = 2012 }

%0 Journal Article %1 info3-article-2012-95 %A Jarschel, Michael %A Schlosser, Daniel %A Scheuring, Sven %A Hoßfeld, Tobias %D 2012 %J Mathematical and Computer Modelling %T Gaming in the clouds: QoE and the users’ perspective %X Cloud Gaming is a new kind of service, which combines the successful concepts of Cloud Computing and Online Gaming. It provides the entire game experience to the users remotely from a data center. The player is no longer dependent on a specific type or quality of gaming hardware, but is able to use common devices. The end device only needs a broadband internet connection and the ability to display High Definition (HD) video. While this may reduce hardware costs for users and increase the revenue for developers by leaving out the retail chain, it also raises new challenges for service quality in terms of bandwidth and latency for the underlying network. In this paper we present the results of a subjective user study we conducted into the user-perceived quality of experience (QoE) in Cloud Gaming. We design a measurement environment, that emulates this new type of service, define tests for users to assess the QoE, derive Key Influence Factors (KFI) and influences of content and perception from our results.
Quality of Experience Management for YouTube: Clouds, FoG and the AquareYoum Hoßfeld, Tobias; Liers, Florian; Schatz, Raimund; Staehle, Barbara; Staehle, Dirk; Volkert, Thomas; Wamser, Florian in PIK - Praxis der Informationverarbeitung und -kommunikation (PIK) (2012).
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Over the last decade, Quality of Experience (QoE) has become a new, central paradigm for understanding the quality of networks and services. In particular, the concept has attracted the interest of communication network and service providers, since being able to guarantee good QoE to customers provides an opportunity for differentiation. In this paper we investigate the potential as well as the implementation challenges of QoE management in the Internet. Using YouTube video streaming service as example, we discuss the different elements that are required for the realization of the paradigm-shift towards truly user-centric network orchestration. To this end, we elaborate QoE management requirements for two complementary network scenarios (wireless mesh Internet access networks vs. global Internet delivery) and provide a QoE model for YouTube taking into account impairments like stalling and initial delay. We present two YouTube QoE monitoring approaches operating on the network and the end user level. Finally, we demonstrate how QoE can be dynamically optimized in both network scenarios with two exemplary concepts, AquareYoum and FoG, respectively. Our results show how QoE management can truly improve the user experience while at the same time increase the efficiency of network resource allocation.

@article{info3-article-2012-103, abstract = {Over the last decade, Quality of Experience (QoE) has become a new, central paradigm for understanding the quality of networks and services. In particular, the concept has attracted the interest of communication network and service providers, since being able to guarantee good QoE to customers provides an opportunity for differentiation. In this paper we investigate the potential as well as the implementation challenges of QoE management in the Internet. Using YouTube video streaming service as example, we discuss the different elements that are required for the realization of the paradigm-shift towards truly user-centric network orchestration. To this end, we elaborate QoE management requirements for two complementary network scenarios (wireless mesh Internet access networks vs. global Internet delivery) and provide a QoE model for YouTube taking into account impairments like stalling and initial delay. We present two YouTube QoE monitoring approaches operating on the network and the end user level. Finally, we demonstrate how QoE can be dynamically optimized in both network scenarios with two exemplary concepts, AquareYoum and FoG, respectively. Our results show how QoE management can truly improve the user experience while at the same time increase the efficiency of network resource allocation.}, author = {Hoßfeld, Tobias and Liers, Florian and Schatz, Raimund and Staehle, Barbara and Staehle, Dirk and Volkert, Thomas and Wamser, Florian}, journal = {PIK - Praxis der Informationverarbeitung und -kommunikation (PIK)}, keywords = {sys:hidden:article}, month = 8, title = {Quality of Experience Management for YouTube: Clouds, FoG and the AquareYoum}, year = 2012 }

%0 Journal Article %1 info3-article-2012-103 %A Hoßfeld, Tobias %A Liers, Florian %A Schatz, Raimund %A Staehle, Barbara %A Staehle, Dirk %A Volkert, Thomas %A Wamser, Florian %D 2012 %J PIK - Praxis der Informationverarbeitung und -kommunikation (PIK) %T Quality of Experience Management for YouTube: Clouds, FoG and the AquareYoum %X Over the last decade, Quality of Experience (QoE) has become a new, central paradigm for understanding the quality of networks and services. In particular, the concept has attracted the interest of communication network and service providers, since being able to guarantee good QoE to customers provides an opportunity for differentiation. In this paper we investigate the potential as well as the implementation challenges of QoE management in the Internet. Using YouTube video streaming service as example, we discuss the different elements that are required for the realization of the paradigm-shift towards truly user-centric network orchestration. To this end, we elaborate QoE management requirements for two complementary network scenarios (wireless mesh Internet access networks vs. global Internet delivery) and provide a QoE model for YouTube taking into account impairments like stalling and initial delay. We present two YouTube QoE monitoring approaches operating on the network and the end user level. Finally, we demonstrate how QoE can be dynamically optimized in both network scenarios with two exemplary concepts, AquareYoum and FoG, respectively. Our results show how QoE management can truly improve the user experience while at the same time increase the efficiency of network resource allocation.
Aktuelles Schlagwort: Crowdsourcing Hoßfeld, Tobias; Hirth, Matthias; Tran-Gia, Phuoc in Informatik Spektrum (2012). 35
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Seit der Öffnung des Internets für die Allgemeinheit Anfang der 90er Jahre hat eine rasante Entwicklung stattgefunden. Neue Paradigmen wie Peer-to-Peer (P2P), Web 2.0 oder Cloud Computing führen zu neuartigen Diensten und Anwendungen, welche bei den Anwendern längst etabliert sind und einen Großteil des Datenverkehrs im Internet ausmachen. Beispiele hierfür sind unter anderem P2P-Anwendungen wie BitTorrent zum Austausch riesiger Datenmengen, Skype für Sprach- und Videokonferenzen, Soziale Medien wie Facebook oder Twitter, Cloud Anwendungen wie DropBox als synchronisiertes Netzwerk-Dateisystem für verteilte Rechner oder Cloud Gaming. Aktuell taucht ein neues Schlagwort im Internet auf: „Crowdsourcing“. Einige Aufgaben und Probleme, die für Menschen relativ einfach zu lösen sind, können derzeit selbst von modernen Machine Clouds noch nicht algorithmisch bewältigt werden. Hierzu zählen etwa Text- und Bilderkennung, das Verifizieren, Analysieren und Kategorisieren von Videoinhalten, das Schaffen von Wissen, das Verbessern und Kreieren von Produkten oder wissenschaftliche Forschung. Diese stellen Anwendungsgebiete von Crowdsourcing dar. Statt (oder zusätzlich zu) Machine Clouds wird die Masse der Internetnutzer in die Wertschöpfungskette eingebunden. Man spricht hier auch von Human Clouds. Neben Sozialen Medien ist Crowdsourcing eine der wichtigsten aktuell aufstrebenden Technologien und Geschäftsmodelle im Internet, die die Zukunft des Arbeitens und der Arbeitsorganisation von Grund auf verändern wird. Die wirtschaftliche und gesellschaftliche Bedeutung von Crowdsourcing-Plattformen wächst ständig und fördert die Entstehung neuer Formen der Arbeitsorganisation. Jobs in Crowdsourcing-Plattformen besitzen eine viel kleinere Granularität im Vergleich zu denen im traditionellen Outsourcing bzw. Outtasking Bereich. Das Aktuelle Schlagwort beleuchtet den Begriff „Crowdsourcing“ näher und wird zunächst wichtige Begriffe einführen, bevor die Anwendungsgebiete von Crowdsourcing sowie dessen Bedeutung in der Praxis und zukünftige Weiterentwicklung betrachtet werden.

@article{info3-article-2012-102, abstract = {Seit der Öffnung des Internets für die Allgemeinheit Anfang der 90er Jahre hat eine rasante Entwicklung stattgefunden. Neue Paradigmen wie Peer-to-Peer (P2P), Web 2.0 oder Cloud Computing führen zu neuartigen Diensten und Anwendungen, welche bei den Anwendern längst etabliert sind und einen Großteil des Datenverkehrs im Internet ausmachen. Beispiele hierfür sind unter anderem P2P-Anwendungen wie BitTorrent zum Austausch riesiger Datenmengen, Skype für Sprach- und Videokonferenzen, Soziale Medien wie Facebook oder Twitter, Cloud Anwendungen wie DropBox als synchronisiertes Netzwerk-Dateisystem für verteilte Rechner oder Cloud Gaming. Aktuell taucht ein neues Schlagwort im Internet auf: „Crowdsourcing“. Einige Aufgaben und Probleme, die für Menschen relativ einfach zu lösen sind, können derzeit selbst von modernen Machine Clouds noch nicht algorithmisch bewältigt werden. Hierzu zählen etwa Text- und Bilderkennung, das Verifizieren, Analysieren und Kategorisieren von Videoinhalten, das Schaffen von Wissen, das Verbessern und Kreieren von Produkten oder wissenschaftliche Forschung. Diese stellen Anwendungsgebiete von Crowdsourcing dar. Statt (oder zusätzlich zu) Machine Clouds wird die Masse der Internetnutzer in die Wertschöpfungskette eingebunden. Man spricht hier auch von Human Clouds. Neben Sozialen Medien ist Crowdsourcing eine der wichtigsten aktuell aufstrebenden Technologien und Geschäftsmodelle im Internet, die die Zukunft des Arbeitens und der Arbeitsorganisation von Grund auf verändern wird. Die wirtschaftliche und gesellschaftliche Bedeutung von Crowdsourcing-Plattformen wächst ständig und fördert die Entstehung neuer Formen der Arbeitsorganisation. Jobs in Crowdsourcing-Plattformen besitzen eine viel kleinere Granularität im Vergleich zu denen im traditionellen Outsourcing bzw. Outtasking Bereich. Das Aktuelle Schlagwort beleuchtet den Begriff „Crowdsourcing“ näher und wird zunächst wichtige Begriffe einführen, bevor die Anwendungsgebiete von Crowdsourcing sowie dessen Bedeutung in der Praxis und zukünftige Weiterentwicklung betrachtet werden.}, author = {Hoßfeld, Tobias and Hirth, Matthias and Tran-Gia, Phuoc}, journal = {Informatik Spektrum}, keywords = {sys:hidden:article}, month = 4, title = {Aktuelles Schlagwort: Crowdsourcing}, volume = 35, year = 2012 }

%0 Journal Article %1 info3-article-2012-102 %A Hoßfeld, Tobias %A Hirth, Matthias %A Tran-Gia, Phuoc %D 2012 %J Informatik Spektrum %T Aktuelles Schlagwort: Crowdsourcing %V 35 %X Seit der Öffnung des Internets für die Allgemeinheit Anfang der 90er Jahre hat eine rasante Entwicklung stattgefunden. Neue Paradigmen wie Peer-to-Peer (P2P), Web 2.0 oder Cloud Computing führen zu neuartigen Diensten und Anwendungen, welche bei den Anwendern längst etabliert sind und einen Großteil des Datenverkehrs im Internet ausmachen. Beispiele hierfür sind unter anderem P2P-Anwendungen wie BitTorrent zum Austausch riesiger Datenmengen, Skype für Sprach- und Videokonferenzen, Soziale Medien wie Facebook oder Twitter, Cloud Anwendungen wie DropBox als synchronisiertes Netzwerk-Dateisystem für verteilte Rechner oder Cloud Gaming. Aktuell taucht ein neues Schlagwort im Internet auf: „Crowdsourcing“. Einige Aufgaben und Probleme, die für Menschen relativ einfach zu lösen sind, können derzeit selbst von modernen Machine Clouds noch nicht algorithmisch bewältigt werden. Hierzu zählen etwa Text- und Bilderkennung, das Verifizieren, Analysieren und Kategorisieren von Videoinhalten, das Schaffen von Wissen, das Verbessern und Kreieren von Produkten oder wissenschaftliche Forschung. Diese stellen Anwendungsgebiete von Crowdsourcing dar. Statt (oder zusätzlich zu) Machine Clouds wird die Masse der Internetnutzer in die Wertschöpfungskette eingebunden. Man spricht hier auch von Human Clouds. Neben Sozialen Medien ist Crowdsourcing eine der wichtigsten aktuell aufstrebenden Technologien und Geschäftsmodelle im Internet, die die Zukunft des Arbeitens und der Arbeitsorganisation von Grund auf verändern wird. Die wirtschaftliche und gesellschaftliche Bedeutung von Crowdsourcing-Plattformen wächst ständig und fördert die Entstehung neuer Formen der Arbeitsorganisation. Jobs in Crowdsourcing-Plattformen besitzen eine viel kleinere Granularität im Vergleich zu denen im traditionellen Outsourcing bzw. Outtasking Bereich. Das Aktuelle Schlagwort beleuchtet den Begriff „Crowdsourcing“ näher und wird zunächst wichtige Begriffe einführen, bevor die Anwendungsgebiete von Crowdsourcing sowie dessen Bedeutung in der Praxis und zukünftige Weiterentwicklung betrachtet werden.
Provisioning and Operation of Virtual Networks Meier, Sebastian; Barisch, Marc; Kirstädter, Andreas; Schlosser, Daniel; Duelli, Michael; Jarschel, Michael; Hoßfeld, Tobias; Hoffmann, Klaus; Hoffmann, Marco; Kellerer, Wolfgang; Khan, Ashiq; Jurca, Dan; Kozu, Kazuyuki in Electronic Communications of the EASST, Kommunikation in Verteilten Systemen 2011 (2011). 37
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In today’s Internet, requirements of services regarding the underlying transport network are very diverse. In the future, this diversity will increase and make it harder to accommodate all services in a single network. A possible approach to keep up with this diversity in future networks is the deployment of isolated, custom tailored networks on top of a single shared physical substrate. The COMCON (COntrol and Monitoring of COexisting Networks) project aims to deﬁne a reference architecture for setup, control, and monitoring of virtual networks on a provider- and operator-grade level. In this paper, we present the building blocks and interfaces of our architecture.

@article{info3-article-2011-87, abstract = {In today’s Internet, requirements of services regarding the underlying transport network are very diverse. In the future, this diversity will increase and make it harder to accommodate all services in a single network. A possible approach to keep up with this diversity in future networks is the deployment of isolated, custom tailored networks on top of a single shared physical substrate. The COMCON (COntrol and Monitoring of COexisting Networks) project aims to deﬁne a reference architecture for setup, control, and monitoring of virtual networks on a provider- and operator-grade level. In this paper, we present the building blocks and interfaces of our architecture.}, author = {Meier, Sebastian and Barisch, Marc and Kirstädter, Andreas and Schlosser, Daniel and Duelli, Michael and Jarschel, Michael and Hoßfeld, Tobias and Hoffmann, Klaus and Hoffmann, Marco and Kellerer, Wolfgang and Khan, Ashiq and Jurca, Dan and Kozu, Kazuyuki}, journal = {Electronic Communications of the EASST, Kommunikation in Verteilten Systemen 2011}, keywords = {sys:hidden:article}, month = 3, title = {Provisioning and Operation of Virtual Networks}, volume = 37, year = 2011 }

%0 Journal Article %1 info3-article-2011-87 %A Meier, Sebastian %A Barisch, Marc %A Kirstädter, Andreas %A Schlosser, Daniel %A Duelli, Michael %A Jarschel, Michael %A Hoßfeld, Tobias %A Hoffmann, Klaus %A Hoffmann, Marco %A Kellerer, Wolfgang %A Khan, Ashiq %A Jurca, Dan %A Kozu, Kazuyuki %D 2011 %J Electronic Communications of the EASST, Kommunikation in Verteilten Systemen 2011 %T Provisioning and Operation of Virtual Networks %V 37 %X In today’s Internet, requirements of services regarding the underlying transport network are very diverse. In the future, this diversity will increase and make it harder to accommodate all services in a single network. A possible approach to keep up with this diversity in future networks is the deployment of isolated, custom tailored networks on top of a single shared physical substrate. The COMCON (COntrol and Monitoring of COexisting Networks) project aims to deﬁne a reference architecture for setup, control, and monitoring of virtual networks on a provider- and operator-grade level. In this paper, we present the building blocks and interfaces of our architecture.
Mitigating Unfairness in Locality-Aware Peer-to-Peer Networks Lehrieder, Frank; Oechsner, Simon; Hoßfeld, Tobias; Staehle, Dirk; Despotovic, Zoran; Kellerer, Wolfgang; Michel, Maximilian in International Journal of Network Management (IJNM), Special Issue on Economic Traffic Management (2011). 21(1)
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Locality-awareness is considered as a promising approach to increase the efficiency of content distribution by peer-to-peer (P2P) networks, e.g., BitTorrent. It is intended to reduce the inter-domain traffic which is costly for Internet service providers (ISPs) and to simultaneously increase the performance from the viewpoint of the P2P users, i.e., to shorten download times. This win-win situation should be achieved by a preferred exchange of information between peers which are located closely to each other in the underlying network topology. A set of studies shows that these approaches can lead to a win-win situation under certain conditions, and to a win-no lose situation in most cases. However, the scenarios used mostly assume homogeneous peer distributions. This is not the case in practice according to recent measurement studies. Therefore, we extend previous work in this paper by studying scenarios with real-life, skewed peer distributions. We show that even a win-no lose situation is difficult to achieve under those conditions and that the actual impact for a specific peer heavily depends on the used locality-aware peer selection and the specific scenario. This contradicts the principle of economic traffic management (ETM) which aims for a solution where all involved players benefit and consequently have an incentive to adopt locality-awareness. Therefore, we propose and evaluate refinements of current proposals, achieving that all users of P2P networks can be sure that their application performance is not reduced. This mitigates the unfairness introduced by current proposals which is a key requirement for a broad acceptance of the concept of locality-awareness in the user community of P2P networks.

@article{info3-article-2011-82, abstract = {Locality-awareness is considered as a promising approach to increase the efficiency of content distribution by peer-to-peer (P2P) networks, e.g., BitTorrent. It is intended to reduce the inter-domain traffic which is costly for Internet service providers (ISPs) and to simultaneously increase the performance from the viewpoint of the P2P users, i.e., to shorten download times. This win-win situation should be achieved by a preferred exchange of information between peers which are located closely to each other in the underlying network topology. A set of studies shows that these approaches can lead to a win-win situation under certain conditions, and to a win-no lose situation in most cases. However, the scenarios used mostly assume homogeneous peer distributions. This is not the case in practice according to recent measurement studies. Therefore, we extend previous work in this paper by studying scenarios with real-life, skewed peer distributions. We show that even a win-no lose situation is difficult to achieve under those conditions and that the actual impact for a specific peer heavily depends on the used locality-aware peer selection and the specific scenario. This contradicts the principle of economic traffic management (ETM) which aims for a solution where all involved players benefit and consequently have an incentive to adopt locality-awareness. Therefore, we propose and evaluate refinements of current proposals, achieving that all users of P2P networks can be sure that their application performance is not reduced. This mitigates the unfairness introduced by current proposals which is a key requirement for a broad acceptance of the concept of locality-awareness in the user community of P2P networks.}, author = {Lehrieder, Frank and Oechsner, Simon and Hoßfeld, Tobias and Staehle, Dirk and Despotovic, Zoran and Kellerer, Wolfgang and Michel, Maximilian}, journal = {International Journal of Network Management (IJNM), Special Issue on Economic Traffic Management}, keywords = {sys:hidden:article}, month = 1, title = {Mitigating Unfairness in Locality-Aware Peer-to-Peer Networks}, volume = {21(1)}, year = 2011 }

%0 Journal Article %1 info3-article-2011-82 %A Lehrieder, Frank %A Oechsner, Simon %A Hoßfeld, Tobias %A Staehle, Dirk %A Despotovic, Zoran %A Kellerer, Wolfgang %A Michel, Maximilian %D 2011 %J International Journal of Network Management (IJNM), Special Issue on Economic Traffic Management %T Mitigating Unfairness in Locality-Aware Peer-to-Peer Networks %V 21(1) %X Locality-awareness is considered as a promising approach to increase the efficiency of content distribution by peer-to-peer (P2P) networks, e.g., BitTorrent. It is intended to reduce the inter-domain traffic which is costly for Internet service providers (ISPs) and to simultaneously increase the performance from the viewpoint of the P2P users, i.e., to shorten download times. This win-win situation should be achieved by a preferred exchange of information between peers which are located closely to each other in the underlying network topology. A set of studies shows that these approaches can lead to a win-win situation under certain conditions, and to a win-no lose situation in most cases. However, the scenarios used mostly assume homogeneous peer distributions. This is not the case in practice according to recent measurement studies. Therefore, we extend previous work in this paper by studying scenarios with real-life, skewed peer distributions. We show that even a win-no lose situation is difficult to achieve under those conditions and that the actual impact for a specific peer heavily depends on the used locality-aware peer selection and the specific scenario. This contradicts the principle of economic traffic management (ETM) which aims for a solution where all involved players benefit and consequently have an incentive to adopt locality-awareness. Therefore, we propose and evaluate refinements of current proposals, achieving that all users of P2P networks can be sure that their application performance is not reduced. This mitigates the unfairness introduced by current proposals which is a key requirement for a broad acceptance of the concept of locality-awareness in the user community of P2P networks.
Characterization of BitTorrent Swarms and their Distribution in the Internet Hoßfeld, Tobias; Lehrieder, Frank; Hock, David; Oechsner, Simon; Despotovic, Zoran; Kellerer, Wolfgang; Michel, Maximilian in Computer Networks (2011). 55(5) 1197–1215.
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The optimization of overlay traffic resulting from applications such as BitTorrent is a challenge addressed by several recent research initiatives. However, the assessment of such optimization techniques and their performance in the real Internet remains difficult. Despite a considerable set of works measuring real-life BitTorrent swarms, several characteristics of those swarms relevant for the optimization of overlay traffic have not yet been investigated. In this work, we address this lack of realistic swarm statistics by presenting our measurement results. In particular, we provide a statistical characterization of the swarm sizes, the distribution of peers over autonomous systems (ASs), the fraction of peers in the largest AS, and the size of the shared files. To this end, we consider different types of shared content and identify particular characteristics of regional swarms. The selection of the presented data is inspired by ongoing discussions in the IETF working group on application layer traffic optimization (ALTO). Our study is intended to provide input for the design and the assessment of ALTO solutions for BitTorrent, but the applicability of the results is not limited to that purpose.

@article{info3-article-2011-83, abstract = {The optimization of overlay traffic resulting from applications such as BitTorrent is a challenge addressed by several recent research initiatives. However, the assessment of such optimization techniques and their performance in the real Internet remains difficult. Despite a considerable set of works measuring real-life BitTorrent swarms, several characteristics of those swarms relevant for the optimization of overlay traffic have not yet been investigated. In this work, we address this lack of realistic swarm statistics by presenting our measurement results. In particular, we provide a statistical characterization of the swarm sizes, the distribution of peers over autonomous systems (ASs), the fraction of peers in the largest AS, and the size of the shared files. To this end, we consider different types of shared content and identify particular characteristics of regional swarms. The selection of the presented data is inspired by ongoing discussions in the IETF working group on application layer traffic optimization (ALTO). Our study is intended to provide input for the design and the assessment of ALTO solutions for BitTorrent, but the applicability of the results is not limited to that purpose.}, author = {Hoßfeld, Tobias and Lehrieder, Frank and Hock, David and Oechsner, Simon and Despotovic, Zoran and Kellerer, Wolfgang and Michel, Maximilian}, journal = {Computer Networks}, keywords = {sys:hidden:article}, month = 4, pages = {1197-1215}, title = {Characterization of BitTorrent Swarms and their Distribution in the Internet}, volume = {55(5)}, year = 2011 }

%0 Journal Article %1 info3-article-2011-83 %A Hoßfeld, Tobias %A Lehrieder, Frank %A Hock, David %A Oechsner, Simon %A Despotovic, Zoran %A Kellerer, Wolfgang %A Michel, Maximilian %D 2011 %J Computer Networks %P 1197-1215 %T Characterization of BitTorrent Swarms and their Distribution in the Internet %V 55(5) %X The optimization of overlay traffic resulting from applications such as BitTorrent is a challenge addressed by several recent research initiatives. However, the assessment of such optimization techniques and their performance in the real Internet remains difficult. Despite a considerable set of works measuring real-life BitTorrent swarms, several characteristics of those swarms relevant for the optimization of overlay traffic have not yet been investigated. In this work, we address this lack of realistic swarm statistics by presenting our measurement results. In particular, we provide a statistical characterization of the swarm sizes, the distribution of peers over autonomous systems (ASs), the fraction of peers in the largest AS, and the size of the shared files. To this end, we consider different types of shared content and identify particular characteristics of regional swarms. The selection of the presented data is inspired by ongoing discussions in the IETF working group on application layer traffic optimization (ALTO). Our study is intended to provide input for the design and the assessment of ALTO solutions for BitTorrent, but the applicability of the results is not limited to that purpose.
EuroView 2010: Visions of Future Generation Networks Hoßfeld, Tobias; Tran-Gia, Phuoc in Computer Communications Review CCR (2011). Volume 41, Number 2
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On August 2nd – 3rd, 2010, the EuroView 2010 workshop on 'Visions of Future Generation Networks' was held at the University of Würzburg. The event was sponsored by the European Network of Excellence Euro-NF, the German Information Technology Society ITG, and the International Teletraffic Congress ITC. EuroView 2010 brought together Internet and network technology researchers, network providers, as well as equipment and device manufacturers. In 2010, the focus was on 'Future Internet Design and Experimental Facilities' and on current efforts towards a Future Internet. Special sessions were organized reflecting the latest results of selected testbed expert groups as well as current and future national and international collaborative projects: (1) the German G-Lab project offering a national platform for Future Internet studies, (2) the Future Internet Activities in the European Framework FP7 organized by Max Lemke, and (3) the GENI project in US organized by Aaron Falk. A keynote talk was given by Lawrence Landweber on the challenges and paradigms emerging in the Future (Inter)Network.

@article{info3-article-2011-89, abstract = {On August 2nd – 3rd, 2010, the EuroView 2010 workshop on 'Visions of Future Generation Networks' was held at the University of Würzburg. The event was sponsored by the European Network of Excellence Euro-NF, the German Information Technology Society ITG, and the International Teletraffic Congress ITC. EuroView 2010 brought together Internet and network technology researchers, network providers, as well as equipment and device manufacturers. In 2010, the focus was on 'Future Internet Design and Experimental Facilities' and on current efforts towards a Future Internet. Special sessions were organized reflecting the latest results of selected testbed expert groups as well as current and future national and international collaborative projects: (1) the German G-Lab project offering a national platform for Future Internet studies, (2) the Future Internet Activities in the European Framework FP7 organized by Max Lemke, and (3) the GENI project in US organized by Aaron Falk. A keynote talk was given by Lawrence Landweber on the challenges and paradigms emerging in the Future (Inter)Network.}, author = {Hoßfeld, Tobias and Tran-Gia, Phuoc}, journal = {Computer Communications Review CCR}, keywords = {sys:hidden:article}, month = 7, title = {EuroView 2010: Visions of Future Generation Networks}, volume = {Volume 41, Number 2}, year = 2011 }

%0 Journal Article %1 info3-article-2011-89 %A Hoßfeld, Tobias %A Tran-Gia, Phuoc %D 2011 %J Computer Communications Review CCR %T EuroView 2010: Visions of Future Generation Networks %V Volume 41, Number 2 %X On August 2nd – 3rd, 2010, the EuroView 2010 workshop on 'Visions of Future Generation Networks' was held at the University of Würzburg. The event was sponsored by the European Network of Excellence Euro-NF, the German Information Technology Society ITG, and the International Teletraffic Congress ITC. EuroView 2010 brought together Internet and network technology researchers, network providers, as well as equipment and device manufacturers. In 2010, the focus was on 'Future Internet Design and Experimental Facilities' and on current efforts towards a Future Internet. Special sessions were organized reflecting the latest results of selected testbed expert groups as well as current and future national and international collaborative projects: (1) the German G-Lab project offering a national platform for Future Internet studies, (2) the Future Internet Activities in the European Framework FP7 organized by Max Lemke, and (3) the GENI project in US organized by Aaron Falk. A keynote talk was given by Lawrence Landweber on the challenges and paradigms emerging in the Future (Inter)Network.
Towards Quality of Experience-based Reputation Models for Future Web Service Provisioning Ciszkowski, Tomasz; Mazurczyk, Wojciech; Kotulski, Zbigniew; Hoßfeld, Tobias; Fiedler, Markus; Collange, Denis in Special Issue of the Springer Telecommunication Systems Journal: Future Internet Services and Architectures - Trends and Visions, print available in 2013 (2010). 51 283–295.
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This paper concerns the applicability of reputations systems for assessing Quality of Experience (QoE) for web services in the Future Internet. Reputation systems provide mechanisms to manage subjective opinions in societies and yield a general scoring of a particular behavior. Thus, they are likely to become an important ingredient of the Future Internet. Parameters under evaluation by a reputation system may vary greatly and, particularly, may be chosen to assess the users' satisfaction with (composite) web services. Currently, this satisfaction is usually expressed by QoE, which represents subjective users' opinions. The goal of this paper is to present a novel framework of web services where a reputation system is incorporated for tracking and predicting of users' satisfaction. This approach is a beneficial tool which enables providers to facilitate service adaptation according to users' expectations and maintain QoE at a satisfactory level. Presented reputation systems operate in an environment of composite services that integrate client and server-side. This approach is highly suitable for effective QoE differentiating and maximizing user experience for specific customer profiles as even the service and network resources are shared.

@article{info3-article-2010-77, abstract = {This paper concerns the applicability of reputations systems for assessing Quality of Experience (QoE) for web services in the Future Internet. Reputation systems provide mechanisms to manage subjective opinions in societies and yield a general scoring of a particular behavior. Thus, they are likely to become an important ingredient of the Future Internet. Parameters under evaluation by a reputation system may vary greatly and, particularly, may be chosen to assess the users' satisfaction with (composite) web services. Currently, this satisfaction is usually expressed by QoE, which represents subjective users' opinions. The goal of this paper is to present a novel framework of web services where a reputation system is incorporated for tracking and predicting of users' satisfaction. This approach is a beneficial tool which enables providers to facilitate service adaptation according to users' expectations and maintain QoE at a satisfactory level. Presented reputation systems operate in an environment of composite services that integrate client and server-side. This approach is highly suitable for effective QoE differentiating and maximizing user experience for specific customer profiles as even the service and network resources are shared.}, author = {Ciszkowski, Tomasz and Mazurczyk, Wojciech and Kotulski, Zbigniew and Hoßfeld, Tobias and Fiedler, Markus and Collange, Denis}, journal = {Special Issue of the Springer Telecommunication Systems Journal: Future Internet Services and Architectures - Trends and Visions, print available in 2013}, keywords = {sys:hidden:article}, pages = {283-295}, title = {Towards Quality of Experience-based Reputation Models for Future Web Service Provisioning}, volume = 51, year = 2010 }

%0 Journal Article %1 info3-article-2010-77 %A Ciszkowski, Tomasz %A Mazurczyk, Wojciech %A Kotulski, Zbigniew %A Hoßfeld, Tobias %A Fiedler, Markus %A Collange, Denis %D 2010 %J Special Issue of the Springer Telecommunication Systems Journal: Future Internet Services and Architectures - Trends and Visions, print available in 2013 %P 283-295 %T Towards Quality of Experience-based Reputation Models for Future Web Service Provisioning %V 51 %X This paper concerns the applicability of reputations systems for assessing Quality of Experience (QoE) for web services in the Future Internet. Reputation systems provide mechanisms to manage subjective opinions in societies and yield a general scoring of a particular behavior. Thus, they are likely to become an important ingredient of the Future Internet. Parameters under evaluation by a reputation system may vary greatly and, particularly, may be chosen to assess the users' satisfaction with (composite) web services. Currently, this satisfaction is usually expressed by QoE, which represents subjective users' opinions. The goal of this paper is to present a novel framework of web services where a reputation system is incorporated for tracking and predicting of users' satisfaction. This approach is a beneficial tool which enables providers to facilitate service adaptation according to users' expectations and maintain QoE at a satisfactory level. Presented reputation systems operate in an environment of composite services that integrate client and server-side. This approach is highly suitable for effective QoE differentiating and maximizing user experience for specific customer profiles as even the service and network resources are shared.
A Generic Quantitative Relationship between Quality of Experience and Quality of Service Fiedler, Markus; Hoßfeld, Tobias; Tran-Gia, Phuoc in IEEE Network Special Issue on Improving QoE for Network Services (2010).
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Quality of Experience (QoE) ties together user perception, experience and expectations to application and network performance, typically expressed by Quality of Service (QoS) parameters. Quantitative relationships between QoE and QoS are required in order to be able to build effective QoE control mechanisms onto measurable QoS parameters. On this background, this paper proposes a generic formula in which QoE and QoS parameters are connected through an exponential relationship, called IQX hypothesis. The formula relates changes of QoE with respect to QoS to the current level of QoE, is simple to match, and its limit behaviours are straighforward to interpret. It validates the IQX hypothesis for streaming services, where QoE in terms of Mean Opinion Scores (MOS) is expressed as functions of loss and reordering ratio, the latter of which is caused by jitter. For web surfing as the second application area, matchings provided by the IQX hypothesis are shown to outperform previously published logarithmic functions. We conclude that the IQX hypothesis is a strong candidate to be taken into account when deriving relationships between QoE and QoS parameters.

@article{info3-article-2010-71, abstract = {Quality of Experience (QoE) ties together user perception, experience and expectations to application and network performance, typically expressed by Quality of Service (QoS) parameters. Quantitative relationships between QoE and QoS are required in order to be able to build effective QoE control mechanisms onto measurable QoS parameters. On this background, this paper proposes a generic formula in which QoE and QoS parameters are connected through an exponential relationship, called IQX hypothesis. The formula relates changes of QoE with respect to QoS to the current level of QoE, is simple to match, and its limit behaviours are straighforward to interpret. It validates the IQX hypothesis for streaming services, where QoE in terms of Mean Opinion Scores (MOS) is expressed as functions of loss and reordering ratio, the latter of which is caused by jitter. For web surfing as the second application area, matchings provided by the IQX hypothesis are shown to outperform previously published logarithmic functions. We conclude that the IQX hypothesis is a strong candidate to be taken into account when deriving relationships between QoE and QoS parameters.}, author = {Fiedler, Markus and Hoßfeld, Tobias and Tran-Gia, Phuoc}, journal = {IEEE Network Special Issue on Improving QoE for Network Services}, keywords = {sys:hidden:article}, month = 6, title = {A Generic Quantitative Relationship between Quality of Experience and Quality of Service}, year = 2010 }

%0 Journal Article %1 info3-article-2010-71 %A Fiedler, Markus %A Hoßfeld, Tobias %A Tran-Gia, Phuoc %D 2010 %J IEEE Network Special Issue on Improving QoE for Network Services %T A Generic Quantitative Relationship between Quality of Experience and Quality of Service %X Quality of Experience (QoE) ties together user perception, experience and expectations to application and network performance, typically expressed by Quality of Service (QoS) parameters. Quantitative relationships between QoE and QoS are required in order to be able to build effective QoE control mechanisms onto measurable QoS parameters. On this background, this paper proposes a generic formula in which QoE and QoS parameters are connected through an exponential relationship, called IQX hypothesis. The formula relates changes of QoE with respect to QoS to the current level of QoE, is simple to match, and its limit behaviours are straighforward to interpret. It validates the IQX hypothesis for streaming services, where QoE in terms of Mean Opinion Scores (MOS) is expressed as functions of loss and reordering ratio, the latter of which is caused by jitter. For web surfing as the second application area, matchings provided by the IQX hypothesis are shown to outperform previously published logarithmic functions. We conclude that the IQX hypothesis is a strong candidate to be taken into account when deriving relationships between QoE and QoS parameters.
Interaction Patterns between P2P Content Distribution Systems and ISPs Dán, György; Stamoulis, George D.; Hoßfeld, Tobias; Oechsner, Simon; Cholda, Piotr; Stankiewicz, Rafal; Papafili, Ioanna in to be published in IEEE Communications Magazine (2010).
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Peer-to-peer (P2P) content distribution systems are a major source of traffic in the Internet, but the application layer protocols they use are mostly unaware of the underlying network in accordance with the layered structure of the Internet’s protocol stack. Nevertheless, the need for improved network efficiency and the business interests of Internet service providers (ISPs) are both strong drivers towards a cross-layer approach in peer-to-peer protocol design, calling for P2P systems that would in some way interact with the ISPs. Recent research shows that the interaction, which can rely on information provided by both parties, can be mutually beneficial. In this paper first we give an overview of the kinds of information that could potentially be exchanged between the P2P systems and the ISPs, and discuss their usefulness and the ease of obtaining and exchanging them. We also present a classification of the possible approaches for interaction based on the level of involvement of the ISPs and the P2P systems, and we discuss the potential strengths and the weaknesses of these approaches.

@article{info3-article-2010-78, abstract = {Peer-to-peer (P2P) content distribution systems are a major source of traffic in the Internet, but the application layer protocols they use are mostly unaware of the underlying network in accordance with the layered structure of the Internet’s protocol stack. Nevertheless, the need for improved network efficiency and the business interests of Internet service providers (ISPs) are both strong drivers towards a cross-layer approach in peer-to-peer protocol design, calling for P2P systems that would in some way interact with the ISPs. Recent research shows that the interaction, which can rely on information provided by both parties, can be mutually beneficial. In this paper first we give an overview of the kinds of information that could potentially be exchanged between the P2P systems and the ISPs, and discuss their usefulness and the ease of obtaining and exchanging them. We also present a classification of the possible approaches for interaction based on the level of involvement of the ISPs and the P2P systems, and we discuss the potential strengths and the weaknesses of these approaches.}, author = {Dán, György and Stamoulis, George D. and Hoßfeld, Tobias and Oechsner, Simon and Cholda, Piotr and Stankiewicz, Rafal and Papafili, Ioanna}, journal = {to be published in IEEE Communications Magazine}, keywords = {ispeer}, title = {Interaction Patterns between P2P Content Distribution Systems and ISPs}, year = 2010 }

%0 Journal Article %1 info3-article-2010-78 %A Dán, György %A Stamoulis, George D. %A Hoßfeld, Tobias %A Oechsner, Simon %A Cholda, Piotr %A Stankiewicz, Rafal %A Papafili, Ioanna %D 2010 %J to be published in IEEE Communications Magazine %T Interaction Patterns between P2P Content Distribution Systems and ISPs %X Peer-to-peer (P2P) content distribution systems are a major source of traffic in the Internet, but the application layer protocols they use are mostly unaware of the underlying network in accordance with the layered structure of the Internet’s protocol stack. Nevertheless, the need for improved network efficiency and the business interests of Internet service providers (ISPs) are both strong drivers towards a cross-layer approach in peer-to-peer protocol design, calling for P2P systems that would in some way interact with the ISPs. Recent research shows that the interaction, which can rely on information provided by both parties, can be mutually beneficial. In this paper first we give an overview of the kinds of information that could potentially be exchanged between the P2P systems and the ISPs, and discuss their usefulness and the ease of obtaining and exchanging them. We also present a classification of the possible approaches for interaction based on the level of involvement of the ISPs and the P2P systems, and we discuss the potential strengths and the weaknesses of these approaches.
Mastering Selfishness and Heterogeneity in Mobile P2P Content Distribution Networks with Multiple Source Download in Cellular Networks Schlosser, Daniel; Hoßfeld, Tobias in Peer-to-Peer Networking and Applications, Special Issue on Mobile P2P Networking and Computing (2009).
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The performance of Peer-to-Peer (P2P) content distribution networks depends highly on the coordination of the peers. This is especially true for cellular networks with mobile and often selfish users, as the resource constraints on accessible bandwidth and battery power are even more limitating in this context. Thus, it is a major challenge to indentify mobile network specific problems and to develop sophisticated cooperation strategies to overcome these difficulties. Cooperation strategies, which are able to cope these problems, are the foundation for efficient mobile file exchange. The detailed performance of the strategies are determined by the peer capabilities and the peer behavior, such as the number of parallel upload connections, the selfishness, or the altruistic re-distribution of data. The purpose of this work is to evaluate and investigate different cooperation strategies which are based on multiple source download and select the best one for mobile scenarios with even leeching peers, i.e. peers which depart as soon as they have finished their download. The question arises whether the cooperation strategy can smoothen the overall performance degradation caused by a selfish peer behavior. As performance indicators the efficiency, fairness, and robustness of the cooperation strategies are applied. The considered scenarios comprise best-case (altruistic peers) and worst-case scenarios (selfish peers). We further propose a new cooperation strategy to improve the file transfer even when mainly selfish peers are present, the CycPriM (cyclic priority masking) strategy. The strategy allows an efficient P2P based content distribution using ordered chunk delivery with only local information available at a peer.

@article{info3-article-2009-58, abstract = {The performance of Peer-to-Peer (P2P) content distribution networks depends highly on the coordination of the peers. This is especially true for cellular networks with mobile and often selfish users, as the resource constraints on accessible bandwidth and battery power are even more limitating in this context. Thus, it is a major challenge to indentify mobile network specific problems and to develop sophisticated cooperation strategies to overcome these difficulties. Cooperation strategies, which are able to cope these problems, are the foundation for efficient mobile file exchange. The detailed performance of the strategies are determined by the peer capabilities and the peer behavior, such as the number of parallel upload connections, the selfishness, or the altruistic re-distribution of data. The purpose of this work is to evaluate and investigate different cooperation strategies which are based on multiple source download and select the best one for mobile scenarios with even leeching peers, i.e. peers which depart as soon as they have finished their download. The question arises whether the cooperation strategy can smoothen the overall performance degradation caused by a selfish peer behavior. As performance indicators the efficiency, fairness, and robustness of the cooperation strategies are applied. The considered scenarios comprise best-case (altruistic peers) and worst-case scenarios (selfish peers). We further propose a new cooperation strategy to improve the file transfer even when mainly selfish peers are present, the CycPriM (cyclic priority masking) strategy. The strategy allows an efficient P2P based content distribution using ordered chunk delivery with only local information available at a peer.}, author = {Schlosser, Daniel and Hoßfeld, Tobias}, journal = {Peer-to-Peer Networking and Applications, Special Issue on Mobile P2P Networking and Computing}, keywords = {sys:hidden:article}, title = {Mastering Selfishness and Heterogeneity in Mobile P2P Content Distribution Networks with Multiple Source Download in Cellular Networks}, year = 2009 }

%0 Journal Article %1 info3-article-2009-58 %A Schlosser, Daniel %A Hoßfeld, Tobias %D 2009 %J Peer-to-Peer Networking and Applications, Special Issue on Mobile P2P Networking and Computing %T Mastering Selfishness and Heterogeneity in Mobile P2P Content Distribution Networks with Multiple Source Download in Cellular Networks %X The performance of Peer-to-Peer (P2P) content distribution networks depends highly on the coordination of the peers. This is especially true for cellular networks with mobile and often selfish users, as the resource constraints on accessible bandwidth and battery power are even more limitating in this context. Thus, it is a major challenge to indentify mobile network specific problems and to develop sophisticated cooperation strategies to overcome these difficulties. Cooperation strategies, which are able to cope these problems, are the foundation for efficient mobile file exchange. The detailed performance of the strategies are determined by the peer capabilities and the peer behavior, such as the number of parallel upload connections, the selfishness, or the altruistic re-distribution of data. The purpose of this work is to evaluate and investigate different cooperation strategies which are based on multiple source download and select the best one for mobile scenarios with even leeching peers, i.e. peers which depart as soon as they have finished their download. The question arises whether the cooperation strategy can smoothen the overall performance degradation caused by a selfish peer behavior. As performance indicators the efficiency, fairness, and robustness of the cooperation strategies are applied. The considered scenarios comprise best-case (altruistic peers) and worst-case scenarios (selfish peers). We further propose a new cooperation strategy to improve the file transfer even when mainly selfish peers are present, the CycPriM (cyclic priority masking) strategy. The strategy allows an efficient P2P based content distribution using ordered chunk delivery with only local information available at a peer.
Emerging Issues in Current Future Internet Design Tran-Gia, Phuoc; Hoßfeld, Tobias; Menth, Michael; Pries, Rastin in e&i Elektrotechnik und Informationstechnik, Special Issue ’Future Internet’, ISSN: 0932-383X (print), ISSN: 1613-7620 (online) (2009). 07/08
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From its inception, the Internet was not intended as the worldwide universal communication platform. It developed over almost four decades to its current state. As a result of this unplanned evolution, we currently witness scalability problems, increased complexity, missing modularity as well as missing flexibility for emerging services. In this report we focus on two selected issues: i) the changing routing paradigm and ii) edge‐based intelligence. We will then present a variety of projects on future Internet and finally assess recently established experimental facilities and their role in the Future Internet design.

@article{info3-article-2009-62, abstract = {From its inception, the Internet was not intended as the worldwide universal communication platform. It developed over almost four decades to its current state. As a result of this unplanned evolution, we currently witness scalability problems, increased complexity, missing modularity as well as missing flexibility for emerging services. In this report we focus on two selected issues: i) the changing routing paradigm and ii) edge‐based intelligence. We will then present a variety of projects on future Internet and finally assess recently established experimental facilities and their role in the Future Internet design.}, author = {Tran-Gia, Phuoc and Hoßfeld, Tobias and Menth, Michael and Pries, Rastin}, journal = {e&i Elektrotechnik und Informationstechnik, Special Issue 'Future Internet', ISSN: 0932-383X (print), ISSN: 1613-7620 (online)}, keywords = {sys:hidden:article}, month = 8, title = {Emerging Issues in Current Future Internet Design}, volume = {07/08}, year = 2009 }

%0 Journal Article %1 info3-article-2009-62 %A Tran-Gia, Phuoc %A Hoßfeld, Tobias %A Menth, Michael %A Pries, Rastin %D 2009 %J e&i Elektrotechnik und Informationstechnik, Special Issue 'Future Internet', ISSN: 0932-383X (print), ISSN: 1613-7620 (online) %T Emerging Issues in Current Future Internet Design %V 07/08 %X From its inception, the Internet was not intended as the worldwide universal communication platform. It developed over almost four decades to its current state. As a result of this unplanned evolution, we currently witness scalability problems, increased complexity, missing modularity as well as missing flexibility for emerging services. In this report we focus on two selected issues: i) the changing routing paradigm and ii) edge‐based intelligence. We will then present a variety of projects on future Internet and finally assess recently established experimental facilities and their role in the Future Internet design.
Challenges in the Development of Mobile P2P Applications and Services Chan Hung, Nguyen; Hoßfeld, Tobias; Ngo Hoang, Giang; Thanh Vinh, Vu; Manh Thang, Nguyen in Vietname Journal on Information and Communication Technologies (2009). E-1, Number 2 (6)
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The recent trends of decentralizing enterprise applications toward the new peer-to-peer (P2P) architecture and the fast growth of wireless communication lead to a new tendency of combining these technologies to inherit their great advantages of mobility, reliability, flexibility and scalability. However, this technological integration raises a large number of new challenges and issues to be addressed. This paper focuses on the challenges of the development of enterprise mobile applications and services based on P2P architecture. Using selected results from related projects, we present and analyze these important issues and also propose an exemplary solution to address some of these issues.

@article{info3-article-2009-65, abstract = {The recent trends of decentralizing enterprise applications toward the new peer-to-peer (P2P) architecture and the fast growth of wireless communication lead to a new tendency of combining these technologies to inherit their great advantages of mobility, reliability, flexibility and scalability. However, this technological integration raises a large number of new challenges and issues to be addressed. This paper focuses on the challenges of the development of enterprise mobile applications and services based on P2P architecture. Using selected results from related projects, we present and analyze these important issues and also propose an exemplary solution to address some of these issues.}, author = {Chan Hung, Nguyen and Hoßfeld, Tobias and Ngo Hoang, Giang and Thanh Vinh, Vu and Manh Thang, Nguyen}, journal = {Vietname Journal on Information and Communication Technologies}, keywords = {sys:hidden:article}, month = 8, title = {Challenges in the Development of Mobile P2P Applications and Services}, volume = {E-1, Number 2 (6)}, year = 2009 }

%0 Journal Article %1 info3-article-2009-65 %A Chan Hung, Nguyen %A Hoßfeld, Tobias %A Ngo Hoang, Giang %A Thanh Vinh, Vu %A Manh Thang, Nguyen %D 2009 %J Vietname Journal on Information and Communication Technologies %T Challenges in the Development of Mobile P2P Applications and Services %V E-1, Number 2 (6) %X The recent trends of decentralizing enterprise applications toward the new peer-to-peer (P2P) architecture and the fast growth of wireless communication lead to a new tendency of combining these technologies to inherit their great advantages of mobility, reliability, flexibility and scalability. However, this technological integration raises a large number of new challenges and issues to be addressed. This paper focuses on the challenges of the development of enterprise mobile applications and services based on P2P architecture. Using selected results from related projects, we present and analyze these important issues and also propose an exemplary solution to address some of these issues.
Efficient Simulation of Large-Scale P2P Networks Binzenhöfer, Andreas; Hoßfeld, Tobias; Kunzmann, Gerald; Eger, Kolja in International Journal of Computational Science and Engineering (IJCSE): Special Issue on Parallel, Distributed and Network-Based Processing (2008).
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@article{info3-article-2008-51, author = {Binzenhöfer, Andreas and Hoßfeld, Tobias and Kunzmann, Gerald and Eger, Kolja}, journal = {International Journal of Computational Science and Engineering (IJCSE): Special Issue on Parallel, Distributed and Network-Based Processing}, keywords = {sys:hidden:article}, month = 3, title = {Efficient Simulation of Large-Scale P2P Networks}, year = 2008 }

%0 Journal Article %1 info3-article-2008-51 %A Binzenhöfer, Andreas %A Hoßfeld, Tobias %A Kunzmann, Gerald %A Eger, Kolja %D 2008 %J International Journal of Computational Science and Engineering (IJCSE): Special Issue on Parallel, Distributed and Network-Based Processing %T Efficient Simulation of Large-Scale P2P Networks
Analysis of Skype VoIP Traffic in UMTS: End-to-End QoS and QoE Measurements Hoßfeld, Tobias; Binzenhöfer, Andreas in Computer Networks (2008). 52 650–666.
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In the future Internet, multi-network services will follow a new paradigm in which the intelligence of the network control is gradually moved to the edge of the network. This impacts both the objective Quality of Service (QoS) of the end-toend connection as well as the subjective Quality of Experience (QoE) as perceived by the end user. Skype already offers such a multi-network Voice-over-IP (VoIP) telephony service today. Due to its ease of use and a high sound quality, it becomes increasingly popular in the wired Internet. UMTS operators promise to offer large data rates which should suffice to support VoIP calls in a mobile environment. However, the success of those applications strongly depends on the corresponding QoE. In this work, we analyze the theoretically achievable as well as the actually achieved quality of IP-based voice calls using Skype. This is done performing measurements in both a real UMTS network and a testbed environment. The latter is used to emulate rate control mechanisms and changing system conditions of UMTS networks. The results show in how far Skype over UMTS is able to keep pace with existing mobile telephony systems and how it reacts to different network characteristics. The investigated performance measures comprise the QoE in terms of the MOS value and the QoS in terms of network-based factors like throughput, packet interarrival times, or packet loss.

@article{info3-article-2008-50, abstract = {In the future Internet, multi-network services will follow a new paradigm in which the intelligence of the network control is gradually moved to the edge of the network. This impacts both the objective Quality of Service (QoS) of the end-toend connection as well as the subjective Quality of Experience (QoE) as perceived by the end user. Skype already offers such a multi-network Voice-over-IP (VoIP) telephony service today. Due to its ease of use and a high sound quality, it becomes increasingly popular in the wired Internet. UMTS operators promise to offer large data rates which should suffice to support VoIP calls in a mobile environment. However, the success of those applications strongly depends on the corresponding QoE. In this work, we analyze the theoretically achievable as well as the actually achieved quality of IP-based voice calls using Skype. This is done performing measurements in both a real UMTS network and a testbed environment. The latter is used to emulate rate control mechanisms and changing system conditions of UMTS networks. The results show in how far Skype over UMTS is able to keep pace with existing mobile telephony systems and how it reacts to different network characteristics. The investigated performance measures comprise the QoE in terms of the MOS value and the QoS in terms of network-based factors like throughput, packet interarrival times, or packet loss.}, author = {Hoßfeld, Tobias and Binzenhöfer, Andreas}, journal = {Computer Networks}, keywords = {sys:hidden:article}, month = 2, pages = {650-666}, title = {Analysis of Skype VoIP Traffic in UMTS: End-to-End QoS and QoE Measurements}, volume = 52, year = 2008 }

%0 Journal Article %1 info3-article-2008-50 %A Hoßfeld, Tobias %A Binzenhöfer, Andreas %D 2008 %J Computer Networks %P 650-666 %T Analysis of Skype VoIP Traffic in UMTS: End-to-End QoS and QoE Measurements %V 52 %X In the future Internet, multi-network services will follow a new paradigm in which the intelligence of the network control is gradually moved to the edge of the network. This impacts both the objective Quality of Service (QoS) of the end-toend connection as well as the subjective Quality of Experience (QoE) as perceived by the end user. Skype already offers such a multi-network Voice-over-IP (VoIP) telephony service today. Due to its ease of use and a high sound quality, it becomes increasingly popular in the wired Internet. UMTS operators promise to offer large data rates which should suffice to support VoIP calls in a mobile environment. However, the success of those applications strongly depends on the corresponding QoE. In this work, we analyze the theoretically achievable as well as the actually achieved quality of IP-based voice calls using Skype. This is done performing measurements in both a real UMTS network and a testbed environment. The latter is used to emulate rate control mechanisms and changing system conditions of UMTS networks. The results show in how far Skype over UMTS is able to keep pace with existing mobile telephony systems and how it reacts to different network characteristics. The investigated performance measures comprise the QoE in terms of the MOS value and the QoS in terms of network-based factors like throughput, packet interarrival times, or packet loss.
Modeling of an Online TV Recording System Hoßfeld, Tobias; Leibnitz, Kenji; Remiche, Marie-Ange in SIGMETRICS Performance Evaluation Review (2007). Volume 35, Number 2
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Recently, new services have emerged which utilize the Internet as a delivery mechanism for multimedia content. With the advent of broadband accesses, more users are willing to download large volume content from servers, such as video files of TV shows. While some popular video services (e.g. YouTube.com) or some broadcasting companies (e.g. ABC.com) use streaming data with Flash technology, some media distributors (e.g. iTunes) offer entire TV shows for download. In this study, we investigate the performance of the German site OnlineTVRecorder.com (OTR), which acts as an online video cassette recorder (VCR) where users can program their favorite shows over a web interface and download the recorded files from a server or its mirrors. These files are offered in different file formats and can consist of several hundred megabytes up to 1GB or more depending on the length of the TV show as well as the encoding format. OTR can, thus, be seen as an example for a server-based content distribution system with large data files. However, as these server farms are often overloaded, new requests are queued when the provided download slots are full. The restriction to a maximum number of simultaneous downloads guarantees a minimal download bandwidth for each user. Additionally, the service offers premium users prioritized access to downloading. The download duration itself depends on the total capacity of the server and the number of users currently sharing this capacity. On the other hand, users who might encounter slow downloads may abort their downloading attempt if their patience is exceeded. In this paper, we discuss analytical modeling approaches which consider the impact of the user’s impatience on the performance of an OTR server with different file size distributions. The paper is organized as follows. After describing the problem and related work, we formulate simple analytical models and compare their performance in terms of download duration and success ratio. Especially, we address the question of how to properly dimension the number of simultaneous downloads at a server in order to optimize the performance of the system and to maximize the user satisfaction.

@article{info3-article-2007-49, abstract = {Recently, new services have emerged which utilize the Internet as a delivery mechanism for multimedia content. With the advent of broadband accesses, more users are willing to download large volume content from servers, such as video files of TV shows. While some popular video services (e.g. YouTube.com) or some broadcasting companies (e.g. ABC.com) use streaming data with Flash technology, some media distributors (e.g. iTunes) offer entire TV shows for download. In this study, we investigate the performance of the German site OnlineTVRecorder.com (OTR), which acts as an online video cassette recorder (VCR) where users can program their favorite shows over a web interface and download the recorded files from a server or its mirrors. These files are offered in different file formats and can consist of several hundred megabytes up to 1GB or more depending on the length of the TV show as well as the encoding format. OTR can, thus, be seen as an example for a server-based content distribution system with large data files. However, as these server farms are often overloaded, new requests are queued when the provided download slots are full. The restriction to a maximum number of simultaneous downloads guarantees a minimal download bandwidth for each user. Additionally, the service offers premium users prioritized access to downloading. The download duration itself depends on the total capacity of the server and the number of users currently sharing this capacity. On the other hand, users who might encounter slow downloads may abort their downloading attempt if their patience is exceeded. In this paper, we discuss analytical modeling approaches which consider the impact of the user’s impatience on the performance of an OTR server with different file size distributions. The paper is organized as follows. After describing the problem and related work, we formulate simple analytical models and compare their performance in terms of download duration and success ratio. Especially, we address the question of how to properly dimension the number of simultaneous downloads at a server in order to optimize the performance of the system and to maximize the user satisfaction.}, author = {Hoßfeld, Tobias and Leibnitz, Kenji and Remiche, Marie-Ange}, journal = {SIGMETRICS Performance Evaluation Review}, keywords = {sys:hidden:article}, month = 9, title = {Modeling of an Online TV Recording System}, volume = {Volume 35, Number 2}, year = 2007 }

%0 Journal Article %1 info3-article-2007-49 %A Hoßfeld, Tobias %A Leibnitz, Kenji %A Remiche, Marie-Ange %D 2007 %J SIGMETRICS Performance Evaluation Review %T Modeling of an Online TV Recording System %V Volume 35, Number 2 %X Recently, new services have emerged which utilize the Internet as a delivery mechanism for multimedia content. With the advent of broadband accesses, more users are willing to download large volume content from servers, such as video files of TV shows. While some popular video services (e.g. YouTube.com) or some broadcasting companies (e.g. ABC.com) use streaming data with Flash technology, some media distributors (e.g. iTunes) offer entire TV shows for download. In this study, we investigate the performance of the German site OnlineTVRecorder.com (OTR), which acts as an online video cassette recorder (VCR) where users can program their favorite shows over a web interface and download the recorded files from a server or its mirrors. These files are offered in different file formats and can consist of several hundred megabytes up to 1GB or more depending on the length of the TV show as well as the encoding format. OTR can, thus, be seen as an example for a server-based content distribution system with large data files. However, as these server farms are often overloaded, new requests are queued when the provided download slots are full. The restriction to a maximum number of simultaneous downloads guarantees a minimal download bandwidth for each user. Additionally, the service offers premium users prioritized access to downloading. The download duration itself depends on the total capacity of the server and the number of users currently sharing this capacity. On the other hand, users who might encounter slow downloads may abort their downloading attempt if their patience is exceeded. In this paper, we discuss analytical modeling approaches which consider the impact of the user’s impatience on the performance of an OTR server with different file size distributions. The paper is organized as follows. After describing the problem and related work, we formulate simple analytical models and compare their performance in terms of download duration and success ratio. Especially, we address the question of how to properly dimension the number of simultaneous downloads at a server in order to optimize the performance of the system and to maximize the user satisfaction.

Book[ to top ]

Performance Modeling and Analysis of Communication Networks Tran-Gia, Phuoc; Hoßfeld, Tobias (2021). Würzburg University Press, https://modeling.systems/.
- [ Abstract ]
- [ BibTeX ]
- [ EndNote ]
This textbook provides an introduction to common methods of performance modeling and analysis of communication systems. These methods form the basis of traffic engineering, teletraffic theory, and analytical system dimensioning. The fundamentals of probability theory, stochastic processes, Markov processes, and embedded Markov chains are presented. Basic queueing models are described with applications in communication networks. Advanced methods are presented that have been frequently used in recent practice, especially discrete-time analysis algorithms, or which go beyond classical performance measures such as Quality of Experience or energy efficiency. Recent examples of modern communication networks include Software Defined Networking and the Internet of Things. Throughout the book, illustrative examples are used to provide practical experience in performance modeling and analysis. Download: https://modeling.systems/

@book{info3-book-2021-1, abstract = {This textbook provides an introduction to common methods of performance modeling and analysis of communication systems. These methods form the basis of traffic engineering, teletraffic theory, and analytical system dimensioning. The fundamentals of probability theory, stochastic processes, Markov processes, and embedded Markov chains are presented. Basic queueing models are described with applications in communication networks. Advanced methods are presented that have been frequently used in recent practice, especially discrete-time analysis algorithms, or which go beyond classical performance measures such as Quality of Experience or energy efficiency. Recent examples of modern communication networks include Software Defined Networking and the Internet of Things. Throughout the book, illustrative examples are used to provide practical experience in performance modeling and analysis. Download: https://modeling.systems/}, address = {https://modeling.systems/}, author = {Tran-Gia, Phuoc and Hoßfeld, Tobias}, booktitle = {Performance Modeling and Analysis of Communication Networks}, keywords = {sys:hidden:book}, publisher = {Würzburg University Press}, title = {Performance Modeling and Analysis of Communication Networks}, year = 2021 }

%0 Book %1 info3-book-2021-1 %A Tran-Gia, Phuoc %A Hoßfeld, Tobias %B Performance Modeling and Analysis of Communication Networks %C https://modeling.systems/ %D 2021 %I Würzburg University Press %T Performance Modeling and Analysis of Communication Networks %X This textbook provides an introduction to common methods of performance modeling and analysis of communication systems. These methods form the basis of traffic engineering, teletraffic theory, and analytical system dimensioning. The fundamentals of probability theory, stochastic processes, Markov processes, and embedded Markov chains are presented. Basic queueing models are described with applications in communication networks. Advanced methods are presented that have been frequently used in recent practice, especially discrete-time analysis algorithms, or which go beyond classical performance measures such as Quality of Experience or energy efficiency. Recent examples of modern communication networks include Software Defined Networking and the Internet of Things. Throughout the book, illustrative examples are used to provide practical experience in performance modeling and analysis. Download: https://modeling.systems/
Evaluation in the Crowd Archambault, Daniel; Purchase, Helen C; Hoßfeld, Tobias (2017). Springer.
- [ BibTeX ]
- [ EndNote ]
@book{info3-misc-2015-1, author = {Archambault, Daniel and Purchase, Helen C and Hoßfeld, Tobias}, booktitle = {Crowdsourcing and Human-Centered Experiments}, keywords = {sys:hidden:book}, publisher = {Springer}, title = {Evaluation in the Crowd}, year = 2017 }

%0 Book %1 info3-misc-2015-1 %A Archambault, Daniel %A Purchase, Helen C %A Hoßfeld, Tobias %B Crowdsourcing and Human-Centered Experiments %D 2017 %I Springer %T Evaluation in the Crowd
Proceedings of The 28th International Teletraffic Congress 2016 (ITC 28) Hoßfeld, Tobias; Chan, Gary; Mark, Brian L.; Timm-Giel, Andreas (2016). ITC, IEEE, ACM, Würzburg, Germany.
- [ BibTeX ]
- [ EndNote ]
@book{info3-book-2016-2, address = {Würzburg, Germany}, author = {Hoßfeld, Tobias and Chan, Gary and Mark, Brian L. and Timm-Giel, Andreas}, keywords = {sys:hidden:book}, month = 9, publisher = {ITC, IEEE, ACM}, title = {Proceedings of The 28th International Teletraffic Congress 2016 (ITC 28)}, year = 2016 }

%0 Book %1 info3-book-2016-2 %A Hoßfeld, Tobias %A Chan, Gary %A Mark, Brian L. %A Timm-Giel, Andreas %C Würzburg, Germany %D 2016 %I ITC, IEEE, ACM %T Proceedings of The 28th International Teletraffic Congress 2016 (ITC 28)
Proceedings of The Fifth Workshop on Perceptual Quality of Systems (PQS) Antons, Jan-Niklas; Egger, Sebastian; Hoßfeld, Tobias; Möller, Sebastian (2016). ISCA, TU Berlin, Germany.
- [ BibTeX ]
- [ EndNote ]
@book{info3-book-2016-3, address = {TU Berlin, Germany}, author = {Antons, Jan-Niklas and Egger, Sebastian and Hoßfeld, Tobias and Möller, Sebastian}, keywords = {sys:hidden:book}, month = 8, publisher = {ISCA}, title = {Proceedings of The Fifth Workshop on Perceptual Quality of Systems (PQS)}, year = 2016 }

%0 Book %1 info3-book-2016-3 %A Antons, Jan-Niklas %A Egger, Sebastian %A Hoßfeld, Tobias %A Möller, Sebastian %C TU Berlin, Germany %D 2016 %I ISCA %T Proceedings of The Fifth Workshop on Perceptual Quality of Systems (PQS)
Proceedings of The Fourth Workshop on Perceptual Quality of Systems (PQS 2013) Schatz, Raimund; Hoßfeld, Tobias (2013). FTW-TECHREPORT-128, FTW, Vienna, Austria.
- [ BibTeX ]
- [ EndNote ]
@book{info3-book-2013-15, address = {FTW, Vienna, Austria}, author = {Schatz, Raimund and Hoßfeld, Tobias}, keywords = {sys:hidden:book}, month = 10, publisher = {FTW-TECHREPORT-128}, title = {Proceedings of The Fourth Workshop on Perceptual Quality of Systems (PQS 2013)}, year = 2013 }

%0 Book %1 info3-book-2013-15 %A Schatz, Raimund %A Hoßfeld, Tobias %C FTW, Vienna, Austria %D 2013 %I FTW-TECHREPORT-128 %T Proceedings of The Fourth Workshop on Perceptual Quality of Systems (PQS 2013)
Proceedings of the Social-aware Economic Traffic Management for Overlay and Cloud Applications Workshop (SETM 2013) Hausheer, David; Hoßfeld, Tobias (2013). 9th International Conference on Network and Service Management (CNSM 2013), Zürich, Switzerland.
- [ BibTeX ]
- [ EndNote ]
@book{info3-book-2013-14, address = {Zürich, Switzerland}, author = {Hausheer, David and Hoßfeld, Tobias}, keywords = {sys:hidden:book}, month = 10, publisher = {9th International Conference on Network and Service Management (CNSM 2013)}, title = {Proceedings of the Social-aware Economic Traffic Management for Overlay and Cloud Applications Workshop (SETM 2013)}, year = 2013 }

%0 Book %1 info3-book-2013-14 %A Hausheer, David %A Hoßfeld, Tobias %C Zürich, Switzerland %D 2013 %I 9th International Conference on Network and Service Management (CNSM 2013) %T Proceedings of the Social-aware Economic Traffic Management for Overlay and Cloud Applications Workshop (SETM 2013)
Incentives, Overlays, and Economic Traffic Control Stamoulis, George D.; Stiller, Burkhard; Hoßfeld, Tobias (2010). Springer, Proceedings of the Third Workshop on Economic Traffic Management (ETM 2010), Amsterdam, The Netherlands.
- [ BibTeX ]
- [ EndNote ]
@book{info3-book-2010-12, address = {Proceedings of the Third Workshop on Economic Traffic Management (ETM 2010), Amsterdam, The Netherlands}, author = {Stamoulis, George D. and Stiller, Burkhard and Hoßfeld, Tobias}, keywords = {sys:hidden:book}, month = 9, publisher = {Springer}, title = {Incentives, Overlays, and Economic Traffic Control}, year = 2010 }

%0 Book %1 info3-book-2010-12 %A Stamoulis, George D. %A Stiller, Burkhard %A Hoßfeld, Tobias %C Proceedings of the Third Workshop on Economic Traffic Management (ETM 2010), Amsterdam, The Netherlands %D 2010 %I Springer %T Incentives, Overlays, and Economic Traffic Control

Incollection[ to top ]

The Value of Context-Awareness in Bandwidth-Challenging HTTP Adaptive Streaming Scenarios Liotou, Eirini; Hoßfeld, Tobias; Moldovan, Christian; Metzger, Florian; Tsolkas, Dimitris; Passas, Nikos in Autonomous Control for a Reliable Internet of Services: Methods, Models, Approaches, Techniques, Algorithms, and Tools, I. Ganchev, R. D. van der Mei, H. van den Berg (eds.) (2018).
- [ Abstract ]
- [ BibTeX ]
- [ EndNote ]
Video streaming has become an indispensable technology in people’s lives, while its usage keeps constantly increasing. The variability, instability and unpredictability of network conditions pose one of the biggest challenges to video streaming. In this chapter, we analyze HTTP Adaptive Streaming, a technology that relieves these issues by adapting the video reproduction to the current network conditions. Particularly, we study how context awareness can be combined with the adaptive streaming logic to design a proactive client-based video streaming strategy. Our results show that such a context-aware strategy manages to successfully mitigate stallings in light of network connectivity problems, such as an outage. Moreover, we analyze the performance of this strategy by comparing it to the optimal case, as well as by considering situations where the awareness of the context lacks reliability.

@incollection{info3-incollection-2018-4, abstract = {Video streaming has become an indispensable technology in people’s lives, while its usage keeps constantly increasing. The variability, instability and unpredictability of network conditions pose one of the biggest challenges to video streaming. In this chapter, we analyze HTTP Adaptive Streaming, a technology that relieves these issues by adapting the video reproduction to the current network conditions. Particularly, we study how context awareness can be combined with the adaptive streaming logic to design a proactive client-based video streaming strategy. Our results show that such a context-aware strategy manages to successfully mitigate stallings in light of network connectivity problems, such as an outage. Moreover, we analyze the performance of this strategy by comparing it to the optimal case, as well as by considering situations where the awareness of the context lacks reliability.}, author = {Liotou, Eirini and Hoßfeld, Tobias and Moldovan, Christian and Metzger, Florian and Tsolkas, Dimitris and Passas, Nikos}, booktitle = {Autonomous Control for a Reliable Internet of Services: Methods, Models, Approaches, Techniques, Algorithms, and Tools}, editor = {Ganchev, Ivan and van der Mei, R. D. and van den Berg, Hans}, keywords = {fullstack}, month = 5, publisher = {Springer International Publishing}, title = {The Value of Context-Awareness in Bandwidth-Challenging HTTP Adaptive Streaming Scenarios}, year = 2018 }

%0 Book Section %1 info3-incollection-2018-4 %A Liotou, Eirini %A Hoßfeld, Tobias %A Moldovan, Christian %A Metzger, Florian %A Tsolkas, Dimitris %A Passas, Nikos %B Autonomous Control for a Reliable Internet of Services: Methods, Models, Approaches, Techniques, Algorithms, and Tools %D 2018 %E Ganchev, Ivan %E van der Mei, R. D. %E van den Berg, Hans %I Springer International Publishing %T The Value of Context-Awareness in Bandwidth-Challenging HTTP Adaptive Streaming Scenarios %X Video streaming has become an indispensable technology in people’s lives, while its usage keeps constantly increasing. The variability, instability and unpredictability of network conditions pose one of the biggest challenges to video streaming. In this chapter, we analyze HTTP Adaptive Streaming, a technology that relieves these issues by adapting the video reproduction to the current network conditions. Particularly, we study how context awareness can be combined with the adaptive streaming logic to design a proactive client-based video streaming strategy. Our results show that such a context-aware strategy manages to successfully mitigate stallings in light of network connectivity problems, such as an outage. Moreover, we analyze the performance of this strategy by comparing it to the optimal case, as well as by considering situations where the awareness of the context lacks reliability.
Context Monitoring for Improved System Performance and QoE Metzger, Florian; Hoßfeld, Tobias; Skorin-Kapov, Lea; Liotou, Eirini; Pocta, Peter; Melvin, Hugh; Siris, Vasilios; Zgank, Andrej; Jarschel, Michael in Autonomous Control for a Reliable Internet of Services: Methods, Models, Approaches, Techniques, Algorithms, and Tools, I. Ganchev, R. D. van der Mei, H. van den Berg (eds.) (2018).
- [ Abstract ]
- [ BibTeX ]
- [ EndNote ]
Whereas some application domains show a certain consensus on the role of system factors, human factors, and context factors, QoE management of multimedia systems and services is still faced with the challenge of identifying the key QoE influence factors. In this chapter, we focus on the potential of enhancing QoE management mechanisms by exploiting valuable context information. To get a good grip on the basics we first discuss a general framework for context monitoring and define context information, including technical, usage, social, economic, temporal, and physical factors. We then iterate the opportunities and challenges in involving context in QoE monitoring solutions, as context may be, e.g., hard to ascertain or very situational. The benefits of including context in QoE monitoring and management are demonstrated through use cases involving video flash crowds as well as online and cloud gaming. Finally, we discuss potential technical realizations of context-aware QoE monitoring and management derived based on the SDN paradigm.

@incollection{info3-incollection-2018-3, abstract = {Whereas some application domains show a certain consensus on the role of system factors, human factors, and context factors, QoE management of multimedia systems and services is still faced with the challenge of identifying the key QoE influence factors. In this chapter, we focus on the potential of enhancing QoE management mechanisms by exploiting valuable context information. To get a good grip on the basics we first discuss a general framework for context monitoring and define context information, including technical, usage, social, economic, temporal, and physical factors. We then iterate the opportunities and challenges in involving context in QoE monitoring solutions, as context may be, e.g., hard to ascertain or very situational. The benefits of including context in QoE monitoring and management are demonstrated through use cases involving video flash crowds as well as online and cloud gaming. Finally, we discuss potential technical realizations of context-aware QoE monitoring and management derived based on the SDN paradigm.}, author = {Metzger, Florian and Hoßfeld, Tobias and Skorin-Kapov, Lea and Liotou, Eirini and Pocta, Peter and Melvin, Hugh and Siris, Vasilios and Zgank, Andrej and Jarschel, Michael}, booktitle = {Autonomous Control for a Reliable Internet of Services: Methods, Models, Approaches, Techniques, Algorithms, and Tools}, editor = {Ganchev, Ivan and van der Mei, R. D. and van den Berg, Hans}, keywords = {ua-net}, month = 5, publisher = {Springer International Publishing}, title = {Context Monitoring for Improved System Performance and QoE}, year = 2018 }

%0 Book Section %1 info3-incollection-2018-3 %A Metzger, Florian %A Hoßfeld, Tobias %A Skorin-Kapov, Lea %A Liotou, Eirini %A Pocta, Peter %A Melvin, Hugh %A Siris, Vasilios %A Zgank, Andrej %A Jarschel, Michael %B Autonomous Control for a Reliable Internet of Services: Methods, Models, Approaches, Techniques, Algorithms, and Tools %D 2018 %E Ganchev, Ivan %E van der Mei, R. D. %E van den Berg, Hans %I Springer International Publishing %T Context Monitoring for Improved System Performance and QoE %X Whereas some application domains show a certain consensus on the role of system factors, human factors, and context factors, QoE management of multimedia systems and services is still faced with the challenge of identifying the key QoE influence factors. In this chapter, we focus on the potential of enhancing QoE management mechanisms by exploiting valuable context information. To get a good grip on the basics we first discuss a general framework for context monitoring and define context information, including technical, usage, social, economic, temporal, and physical factors. We then iterate the opportunities and challenges in involving context in QoE monitoring solutions, as context may be, e.g., hard to ascertain or very situational. The benefits of including context in QoE monitoring and management are demonstrated through use cases involving video flash crowds as well as online and cloud gaming. Finally, we discuss potential technical realizations of context-aware QoE monitoring and management derived based on the SDN paradigm.
State of the Art and Research Challenges in the Area of Autonomous Control for a Reliable Internet of Services Arvidsson, Ake; van den Berg, Hans; Burakowski, Wojciech; Grbac, Tihana Galinac; Ganchev, Ivan; Haddad, Yoram; Hoßfeld, Tobias; Key, Peter; Lassila, Pasi; Leitner, Philipp in Autonomous Control for a Reliable Internet of Services. (2018).
- [ BibTeX ]
- [ EndNote ]
@incollection{info3-incollection-2018-5, author = {Arvidsson, Ake and van den Berg, Hans and Burakowski, Wojciech and Grbac, Tihana Galinac and Ganchev, Ivan and Haddad, Yoram and Hoßfeld, Tobias and Key, Peter and Lassila, Pasi and Leitner, Philipp}, booktitle = {Autonomous Control for a Reliable Internet of Services.}, keywords = {myown}, publisher = {Springer}, title = {State of the Art and Research Challenges in the Area of Autonomous Control for a Reliable Internet of Services}, year = 2018 }

%0 Book Section %1 info3-incollection-2018-5 %A Arvidsson, Ake %A van den Berg, Hans %A Burakowski, Wojciech %A Grbac, Tihana Galinac %A Ganchev, Ivan %A Haddad, Yoram %A Hoßfeld, Tobias %A Key, Peter %A Lassila, Pasi %A Leitner, Philipp %B Autonomous Control for a Reliable Internet of Services. %D 2018 %I Springer %T State of the Art and Research Challenges in the Area of Autonomous Control for a Reliable Internet of Services
Understanding The Crowd: Ethical and Practical Matters in the Academic Use of Crowdsourcing Martin, David; Carpendale, Sheelagh; Gupta, Neha; Hoßfeld, Tobias; Naderi, Babak; Redi, Judith; Siahaan, Ernestasia; Wechsung, Ina in Evaluation in the Crowd: Crowdsourcing and Human-Centred Experiments, D. Archambault, T. Hoßfeld, H. C. Purchase (eds.) (2017).
- [ BibTeX ]
- [ EndNote ]
@incollection{info3-incollection-2017-4, author = {Martin, David and Carpendale, Sheelagh and Gupta, Neha and Hoßfeld, Tobias and Naderi, Babak and Redi, Judith and Siahaan, Ernestasia and Wechsung, Ina}, booktitle = {Evaluation in the Crowd: Crowdsourcing and Human-Centred Experiments}, editor = {Archambault, Daniel and Hoßfeld, Tobias and Purchase, Helen C.}, keywords = {myown}, month = 8, publisher = {Springer}, title = {Understanding The Crowd: Ethical and Practical Matters in the Academic Use of Crowdsourcing}, year = 2017 }

%0 Book Section %1 info3-incollection-2017-4 %A Martin, David %A Carpendale, Sheelagh %A Gupta, Neha %A Hoßfeld, Tobias %A Naderi, Babak %A Redi, Judith %A Siahaan, Ernestasia %A Wechsung, Ina %B Evaluation in the Crowd: Crowdsourcing and Human-Centred Experiments %D 2017 %E Archambault, Daniel %E Hoßfeld, Tobias %E Purchase, Helen C. %I Springer %T Understanding The Crowd: Ethical and Practical Matters in the Academic Use of Crowdsourcing
Evaluation in the Crowd: An Introduction Archambault, Daniel; Purchase, Helen C; Hoßfeld, Tobias in Evaluation in the Crowd. Crowdsourcing and Human-Centered Experiments (2017).
- [ BibTeX ]
- [ EndNote ]
@incollection{info3-incollection-2017-5, author = {Archambault, Daniel and Purchase, Helen C and Hoßfeld, Tobias}, booktitle = {Evaluation in the Crowd. Crowdsourcing and Human-Centered Experiments}, keywords = {myown}, publisher = {Springer, Cham}, title = {Evaluation in the Crowd: An Introduction}, year = 2017 }

%0 Book Section %1 info3-incollection-2017-5 %A Archambault, Daniel %A Purchase, Helen C %A Hoßfeld, Tobias %B Evaluation in the Crowd. Crowdsourcing and Human-Centered Experiments %D 2017 %I Springer, Cham %T Evaluation in the Crowd: An Introduction
Crowdsourcing Quality of Experience Experiments Egger-Lampl, Sebastian; Redi, Judith; Hoßfeld, Tobias; Hirth, Matthias; Möller, Sebastian; Naderi, Babak; Keimel, Christian; Saupe, Dietmar in Evaluation in the Crowd. Crowdsourcing and Human-Centered Experiments, A. D., P. H., H. T. (eds.) (2017).
- [ BibTeX ]
- [ EndNote ]
@incollection{info3-incollection-2017-2, author = {Egger-Lampl, Sebastian and Redi, Judith and Hoßfeld, Tobias and Hirth, Matthias and Möller, Sebastian and Naderi, Babak and Keimel, Christian and Saupe, Dietmar}, booktitle = {Evaluation in the Crowd. Crowdsourcing and Human-Centered Experiments}, editor = {D., Archambault and H., Purchase and T., Hoßfeld}, keywords = {myown}, month = 9, publisher = {Springer}, title = {Crowdsourcing Quality of Experience Experiments}, year = 2017 }

%0 Book Section %1 info3-incollection-2017-2 %A Egger-Lampl, Sebastian %A Redi, Judith %A Hoßfeld, Tobias %A Hirth, Matthias %A Möller, Sebastian %A Naderi, Babak %A Keimel, Christian %A Saupe, Dietmar %B Evaluation in the Crowd. Crowdsourcing and Human-Centered Experiments %D 2017 %E D., Archambault %E H., Purchase %E T., Hoßfeld %I Springer %T Crowdsourcing Quality of Experience Experiments
SDN-Enabled Energy-Efficient Network Management Jarschel, Michael; Hoßfeld, Tobias; Davoli, Franco; Bolla, Raffaele; Bruschi, Roberto; Carrega, Alessandro in Green Communications: Principles, Concepts and Practice, K. Samdanis, P. Rost, A. Maeder, M. Meo, C. Verikoukis (eds.) (2015).
- [ BibTeX ]
- [ EndNote ]
@incollection{info3-incollection-2015-1, author = {Jarschel, Michael and Hoßfeld, Tobias and Davoli, Franco and Bolla, Raffaele and Bruschi, Roberto and Carrega, Alessandro}, booktitle = {Green Communications: Principles, Concepts and Practice}, editor = {Samdanis, Konstantinos and Rost, Peter and Maeder, Andreas and Meo, Michela and Verikoukis, Christos}, keywords = {myown}, publisher = {John Wiley & Sons, Ltd}, title = {SDN-Enabled Energy-Efficient Network Management}, year = 2015 }

%0 Book Section %1 info3-incollection-2015-1 %A Jarschel, Michael %A Hoßfeld, Tobias %A Davoli, Franco %A Bolla, Raffaele %A Bruschi, Roberto %A Carrega, Alessandro %B Green Communications: Principles, Concepts and Practice %D 2015 %E Samdanis, Konstantinos %E Rost, Peter %E Maeder, Andreas %E Meo, Michela %E Verikoukis, Christos %I John Wiley & Sons, Ltd %T SDN-Enabled Energy-Efficient Network Management
Crowdsourcing in QoE Evaluation Hoßfeld, Tobias; Keimel, Christian in Quality of Experience: Advanced Concepts, Applications and Methods, A. R. Sebastian Möller (ed.) (2014).
- [ Abstract ]
- [ BibTeX ]
- [ EndNote ]
Crowdsourcing enables new possibilities for QoE evaluation by moving the evaluation task from the traditional laboratory environment into the Internet, allowing researchers to easily access a global pool of subjects for the evaluation task. This makes it not only possible to include a more diverse population and real-life environments into the evaluation, but also reduces the turn-around time and increases the number of subjects participating in an evaluation campaign significantly by circumventing bottle-necks in traditional laboratory setup. In order to utilise these advantages, the differences between laboratory-based and crowd-based QoE evaluation must be considered and we therefore discuss both these differences and their impact on the QoE evaluation in this chapter.

@incollection{info3-incollection-2014-21, abstract = {Crowdsourcing enables new possibilities for QoE evaluation by moving the evaluation task from the traditional laboratory environment into the Internet, allowing researchers to easily access a global pool of subjects for the evaluation task. This makes it not only possible to include a more diverse population and real-life environments into the evaluation, but also reduces the turn-around time and increases the number of subjects participating in an evaluation campaign significantly by circumventing bottle-necks in traditional laboratory setup. In order to utilise these advantages, the differences between laboratory-based and crowd-based QoE evaluation must be considered and we therefore discuss both these differences and their impact on the QoE evaluation in this chapter.}, author = {Hoßfeld, Tobias and Keimel, Christian}, booktitle = {Quality of Experience: Advanced Concepts, Applications and Methods}, editor = {Sebastian Möller, Alexander Raake}, keywords = {myown}, month = 3, publisher = {Springer: T-Labs Series in Telecommunication Services, ISBN 978-3-319-02680-0,}, title = {Crowdsourcing in QoE Evaluation}, year = 2014 }

%0 Book Section %1 info3-incollection-2014-21 %A Hoßfeld, Tobias %A Keimel, Christian %B Quality of Experience: Advanced Concepts, Applications and Methods %D 2014 %E Sebastian Möller, Alexander Raake %I Springer: T-Labs Series in Telecommunication Services, ISBN 978-3-319-02680-0, %T Crowdsourcing in QoE Evaluation %X Crowdsourcing enables new possibilities for QoE evaluation by moving the evaluation task from the traditional laboratory environment into the Internet, allowing researchers to easily access a global pool of subjects for the evaluation task. This makes it not only possible to include a more diverse population and real-life environments into the evaluation, but also reduces the turn-around time and increases the number of subjects participating in an evaluation campaign significantly by circumventing bottle-necks in traditional laboratory setup. In order to utilise these advantages, the differences between laboratory-based and crowd-based QoE evaluation must be considered and we therefore discuss both these differences and their impact on the QoE evaluation in this chapter.
Social Network Analysis in the Enterprise: Challenges and Opportunities Burger, Valentin; Hock, David; Scholtes, Ingo; Hoßfeld, Tobias; Garcia, David; Seufert, Michael in Socioinformatics - The Social Impact of Interactions between Humans and IT, K. Zweig, W. Neuser, V. Pipek, M. Rohde, I. Scholtes (eds.) (2014).
- [ Abstract ]
- [ BibTeX ]
- [ EndNote ]
- [ Download ]
Enterprise social software tools are increasingly being used to support the communication and collaboration between employees, as well as to facilitate the collaborative organisation of information and knowledge within companies. Not only do these tools help to develop and maintain an efficient social organisation, they also produce massive amounts of fine-grained data on collaborations, communication and other forms of social relationships within an enterprise. In this chapter, we argue that the availability of these data provides unique opportunities to monitor and analyse social structures and their impact on the success and performance of individuals, teams, communities and organisations. We further review methods from the planning, design and optimisation of telecommunication networks and discuss challenges arising when wanting to apply them to optimise the structure of enterprise social networks.

@incollection{info3-incollection-2014-24, abstract = {Enterprise social software tools are increasingly being used to support the communication and collaboration between employees, as well as to facilitate the collaborative organisation of information and knowledge within companies. Not only do these tools help to develop and maintain an efficient social organisation, they also produce massive amounts of fine-grained data on collaborations, communication and other forms of social relationships within an enterprise. In this chapter, we argue that the availability of these data provides unique opportunities to monitor and analyse social structures and their impact on the success and performance of individuals, teams, communities and organisations. We further review methods from the planning, design and optimisation of telecommunication networks and discuss challenges arising when wanting to apply them to optimise the structure of enterprise social networks.}, author = {Burger, Valentin and Hock, David and Scholtes, Ingo and Hoßfeld, Tobias and Garcia, David and Seufert, Michael}, booktitle = {Socioinformatics - The Social Impact of Interactions between Humans and IT}, editor = {Zweig, Katharina and Neuser, Wolfgang and Pipek, Volkmar and Rohde, Markus and Scholtes, Ingo}, keywords = {myown}, month = 8, publisher = {Springer International Publishing}, title = {Social Network Analysis in the Enterprise: Challenges and Opportunities}, year = 2014 }

%0 Book Section %1 info3-incollection-2014-24 %A Burger, Valentin %A Hock, David %A Scholtes, Ingo %A Hoßfeld, Tobias %A Garcia, David %A Seufert, Michael %B Socioinformatics - The Social Impact of Interactions between Humans and IT %D 2014 %E Zweig, Katharina %E Neuser, Wolfgang %E Pipek, Volkmar %E Rohde, Markus %E Scholtes, Ingo %I Springer International Publishing %T Social Network Analysis in the Enterprise: Challenges and Opportunities %X Enterprise social software tools are increasingly being used to support the communication and collaboration between employees, as well as to facilitate the collaborative organisation of information and knowledge within companies. Not only do these tools help to develop and maintain an efficient social organisation, they also produce massive amounts of fine-grained data on collaborations, communication and other forms of social relationships within an enterprise. In this chapter, we argue that the availability of these data provides unique opportunities to monitor and analyse social structures and their impact on the success and performance of individuals, teams, communities and organisations. We further review methods from the planning, design and optimisation of telecommunication networks and discuss challenges arising when wanting to apply them to optimise the structure of enterprise social networks.
Web Browsing Strohmeier, Dominik; Egger, Sebastian; Raake, Alexander; Schatz, Raimund; Hoßfeld, Tobias in Quality of Experience: Advanced Concepts, Applications and Methods, S. R. Sebastian Möller (ed.) (2014).
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The Chapter provides an overview of Quality of Experience research for web-browsing, highlighting recent research trends. It indicates how Web-QoE assessment has evolved from the mapping of technically measured page-load durations to quality estimates to the notion of subjective page load duration. Here, the consideration of the user’s current task and respective role of individual element load durations is discussed. The interactive nature of Web-browsing is further analyzed in terms of temporal effects regarding the subsequent page access of users during typical browsing sessions. Finally, the Chapter provides an outlook on future challenges related with the increasing complexity of web-services and respective page-loading processes.

@incollection{info3-incollection-2014-22, abstract = {The Chapter provides an overview of Quality of Experience research for web-browsing, highlighting recent research trends. It indicates how Web-QoE assessment has evolved from the mapping of technically measured page-load durations to quality estimates to the notion of subjective page load duration. Here, the consideration of the user’s current task and respective role of individual element load durations is discussed. The interactive nature of Web-browsing is further analyzed in terms of temporal effects regarding the subsequent page access of users during typical browsing sessions. Finally, the Chapter provides an outlook on future challenges related with the increasing complexity of web-services and respective page-loading processes.}, author = {Strohmeier, Dominik and Egger, Sebastian and Raake, Alexander and Schatz, Raimund and Hoßfeld, Tobias}, booktitle = {Quality of Experience: Advanced Concepts, Applications and Methods}, editor = {Sebastian Möller, Sebastian Raake}, keywords = {myown}, month = 3, publisher = {Springer: T-Labs Series in Telecommunication Services, ISBN 978-3-319-02680-0,}, title = {Web Browsing}, year = 2014 }

%0 Book Section %1 info3-incollection-2014-22 %A Strohmeier, Dominik %A Egger, Sebastian %A Raake, Alexander %A Schatz, Raimund %A Hoßfeld, Tobias %B Quality of Experience: Advanced Concepts, Applications and Methods %D 2014 %E Sebastian Möller, Sebastian Raake %I Springer: T-Labs Series in Telecommunication Services, ISBN 978-3-319-02680-0, %T Web Browsing %X The Chapter provides an overview of Quality of Experience research for web-browsing, highlighting recent research trends. It indicates how Web-QoE assessment has evolved from the mapping of technically measured page-load durations to quality estimates to the notion of subjective page load duration. Here, the consideration of the user’s current task and respective role of individual element load durations is discussed. The interactive nature of Web-browsing is further analyzed in terms of temporal effects regarding the subsequent page access of users during typical browsing sessions. Finally, the Chapter provides an outlook on future challenges related with the increasing complexity of web-services and respective page-loading processes.
Socially-Aware Traffic Management Seufert, Michael; Darzanos, George; Papafili, Ioanna; Łapacz, Roman; Burger, Valentin; Hoßfeld, Tobias in Socioinformatics - The Social Impact of Interactions between Humans and IT, K. Zweig, W. Neuser, V. Pipek, M. Rohde, I. Scholtes (eds.) (2014).
- [ Abstract ]
- [ BibTeX ]
- [ EndNote ]
- [ Download ]
Socially-aware traffic management utilizes social information to optimize traffic management in the Internet in terms of traffic load, energy consumption, or end user satisfaction. Several use cases can benefit from socially-aware traffic management and the performance of overlay applications can be enhanced. We present existing use cases and their socially-aware approaches and solutions, but also raise discussions on additional benefits from the integration of social information into traffic management as well as practical aspects in this domain.

@incollection{info3-incollection-2014-25, abstract = {Socially-aware traffic management utilizes social information to optimize traffic management in the Internet in terms of traffic load, energy consumption, or end user satisfaction. Several use cases can benefit from socially-aware traffic management and the performance of overlay applications can be enhanced. We present existing use cases and their socially-aware approaches and solutions, but also raise discussions on additional benefits from the integration of social information into traffic management as well as practical aspects in this domain.}, author = {Seufert, Michael and Darzanos, George and Papafili, Ioanna and Łapacz, Roman and Burger, Valentin and Hoßfeld, Tobias}, booktitle = {Socioinformatics - The Social Impact of Interactions between Humans and IT}, editor = {Zweig, Katharina and Neuser, Wolfgang and Pipek, Volkmar and Rohde, Markus and Scholtes, Ingo}, keywords = {smartenit}, month = 8, publisher = {Springer International Publishing}, title = {Socially-Aware Traffic Management}, year = 2014 }

%0 Book Section %1 info3-incollection-2014-25 %A Seufert, Michael %A Darzanos, George %A Papafili, Ioanna %A Łapacz, Roman %A Burger, Valentin %A Hoßfeld, Tobias %B Socioinformatics - The Social Impact of Interactions between Humans and IT %D 2014 %E Zweig, Katharina %E Neuser, Wolfgang %E Pipek, Volkmar %E Rohde, Markus %E Scholtes, Ingo %I Springer International Publishing %T Socially-Aware Traffic Management %X Socially-aware traffic management utilizes social information to optimize traffic management in the Internet in terms of traffic load, energy consumption, or end user satisfaction. Several use cases can benefit from socially-aware traffic management and the performance of overlay applications can be enhanced. We present existing use cases and their socially-aware approaches and solutions, but also raise discussions on additional benefits from the integration of social information into traffic management as well as practical aspects in this domain.
From Packets to People: Quality of Experience as New Measurement Challenge Schatz, Raimund; Hoßfeld, Tobias; Janowski, Lucjan; Egger, Sebastian in Data Traffic Monitoring and Analysis: From measurement, classification and anomaly detection to Quality of experience, C. C. {Ernst Biersack (ed.) (2013).
- [ Abstract ]
- [ BibTeX ]
- [ EndNote ]
Over the course of the last decade, the concept of Quality of Experience (QoE) has gained strong momentum, both from an academic research and an industry perspective. Being linked very closely to the subjective perception of the end user, QoE is supposed to enable a broader, more holistic understanding of the qualitative performance of networked communication systems and thus to complement the traditional, more technology-centric Quality of Service (QoS) perspective. The purpose of this chapter is twofold: firstly, it introduces the reader to QoE by discussing the origins and the evolution of the concept. Secondly, it provides an overview of the current state of the art of QoE research, with focus on work that particularly addresses QoE as a measurement challenge on the technology as well as on the end-user level. This is achieved by surveying the different streams of QoE research that have emerged in the context of Video, Voice and Web services with respect to the following aspects: fundamental relationships and perceptual principles, QoE assessment, modeling and monitoring.

@incollection{info3-incollection-2013-19, abstract = {Over the course of the last decade, the concept of Quality of Experience (QoE) has gained strong momentum, both from an academic research and an industry perspective. Being linked very closely to the subjective perception of the end user, QoE is supposed to enable a broader, more holistic understanding of the qualitative performance of networked communication systems and thus to complement the traditional, more technology-centric Quality of Service (QoS) perspective. The purpose of this chapter is twofold: firstly, it introduces the reader to QoE by discussing the origins and the evolution of the concept. Secondly, it provides an overview of the current state of the art of QoE research, with focus on work that particularly addresses QoE as a measurement challenge on the technology as well as on the end-user level. This is achieved by surveying the different streams of QoE research that have emerged in the context of Video, Voice and Web services with respect to the following aspects: fundamental relationships and perceptual principles, QoE assessment, modeling and monitoring.}, author = {Schatz, Raimund and Hoßfeld, Tobias and Janowski, Lucjan and Egger, Sebastian}, booktitle = {Data Traffic Monitoring and Analysis: From measurement, classification and anomaly detection to Quality of experience}, editor = {{Ernst Biersack, Christian Callegari}, Maja Matijasevic}, keywords = {oekonet}, publisher = {Springer’s Computer Communications and Networks series, Volume 7754}, title = {From Packets to People: Quality of Experience as New Measurement Challenge}, year = 2013 }

%0 Book Section %1 info3-incollection-2013-19 %A Schatz, Raimund %A Hoßfeld, Tobias %A Janowski, Lucjan %A Egger, Sebastian %B Data Traffic Monitoring and Analysis: From measurement, classification and anomaly detection to Quality of experience %D 2013 %E {Ernst Biersack, Christian Callegari} %I Springer’s Computer Communications and Networks series, Volume 7754 %T From Packets to People: Quality of Experience as New Measurement Challenge %X Over the course of the last decade, the concept of Quality of Experience (QoE) has gained strong momentum, both from an academic research and an industry perspective. Being linked very closely to the subjective perception of the end user, QoE is supposed to enable a broader, more holistic understanding of the qualitative performance of networked communication systems and thus to complement the traditional, more technology-centric Quality of Service (QoS) perspective. The purpose of this chapter is twofold: firstly, it introduces the reader to QoE by discussing the origins and the evolution of the concept. Secondly, it provides an overview of the current state of the art of QoE research, with focus on work that particularly addresses QoE as a measurement challenge on the technology as well as on the end-user level. This is achieved by surveying the different streams of QoE research that have emerged in the context of Video, Voice and Web services with respect to the following aspects: fundamental relationships and perceptual principles, QoE assessment, modeling and monitoring.
Internet Video Delivery in YouTube: From Traffic Measurements to Quality of Experience Hoßfeld, Tobias; Schatz, Raimund; Biersack, Ernst; Plissonneau, Louis in Data Traffic Monitoring and Analysis: From measurement, classification and anomaly detection to Quality of experience, C. C. {Ernst Biersack (ed.) (2013).
- [ Abstract ]
- [ BibTeX ]
- [ EndNote ]
This chapter investigates HTTP video streaming over the Internet for the YouTube platform. YouTube is used as concrete example and case study for video delivery over the Internet, since it is not only the most popular online video platform, but also generates a large share of traffic on today’s Internet. We will describe the YouTube infrastructure as well as the underlying mechanisms for optimizing content delivery. Such mechanisms include server selection via DNS as well as application-layer traffic management. Furthermore, the impact of delivery via the Internet on the user experienced quality (QoE) of YouTube video streaming is quantified. In this context, different QoE monitoring approaches are qualitatively compared and evaluated in terms of the accuracy of QoE estimation.

@incollection{info3-incollection-2013-18, abstract = {This chapter investigates HTTP video streaming over the Internet for the YouTube platform. YouTube is used as concrete example and case study for video delivery over the Internet, since it is not only the most popular online video platform, but also generates a large share of traffic on today’s Internet. We will describe the YouTube infrastructure as well as the underlying mechanisms for optimizing content delivery. Such mechanisms include server selection via DNS as well as application-layer traffic management. Furthermore, the impact of delivery via the Internet on the user experienced quality (QoE) of YouTube video streaming is quantified. In this context, different QoE monitoring approaches are qualitatively compared and evaluated in terms of the accuracy of QoE estimation.}, author = {Hoßfeld, Tobias and Schatz, Raimund and Biersack, Ernst and Plissonneau, Louis}, booktitle = {Data Traffic Monitoring and Analysis: From measurement, classification and anomaly detection to Quality of experience}, editor = {{Ernst Biersack, Christian Callegari}, Maja Matijasevic}, keywords = {oekonet}, publisher = {Springer’s Computer Communications and Networks series, Volume 7754}, title = {Internet Video Delivery in YouTube: From Traffic Measurements to Quality of Experience}, year = 2013 }

%0 Book Section %1 info3-incollection-2013-18 %A Hoßfeld, Tobias %A Schatz, Raimund %A Biersack, Ernst %A Plissonneau, Louis %B Data Traffic Monitoring and Analysis: From measurement, classification and anomaly detection to Quality of experience %D 2013 %E {Ernst Biersack, Christian Callegari} %I Springer’s Computer Communications and Networks series, Volume 7754 %T Internet Video Delivery in YouTube: From Traffic Measurements to Quality of Experience %X This chapter investigates HTTP video streaming over the Internet for the YouTube platform. YouTube is used as concrete example and case study for video delivery over the Internet, since it is not only the most popular online video platform, but also generates a large share of traffic on today’s Internet. We will describe the YouTube infrastructure as well as the underlying mechanisms for optimizing content delivery. Such mechanisms include server selection via DNS as well as application-layer traffic management. Furthermore, the impact of delivery via the Internet on the user experienced quality (QoE) of YouTube video streaming is quantified. In this context, different QoE monitoring approaches are qualitatively compared and evaluated in terms of the accuracy of QoE estimation.
Towards a Socially-Aware Management of New Overlay Application Traffic Combined with Energy Efficiency in the Internet (SmartenIT) Stiller, Burkhard; Hausheer, David; Hoßfeld, Tobias in The Future Internet, A. G. Alex Galis (ed.) (2013).
- [ Abstract ]
- [ BibTeX ]
- [ EndNote ]
The Internet has seen a strong move to support overlay applications, which demand a coherent and integrated control in underlying heterogeneous networks in a scalable, resilient, and energy-efficient manner. A tighter integration of network management and overlay service functionality can lead to cross-layer optimization of operations and management, which is a promising approach as it offers a large business potential in operational perspectives for all players involved. Therefore, the objective of this paper is to present SmartenIT (Socially-aware Management of New Overlay Application Traffic combined with Energy Efficiency in the Internet), which targets at an incentive-compatible cross-layer network management for providers of overlay-based application (e.g., cloud applications, content delivery, and social networks), network providers, and end-users. The goal is to ensure a QoE-awareness, by addressing accordingly load and traffic patterns or special application requirements, and exploiting at the same time social awareness (in terms of user relations and interests). Moreover, energy efficiency with respect to both end-user devices and underlying networking infrastructure is tackled to ensure an operationally efficient management. Incentive-compatible network management mechanisms for improving metrics on an inter-domain basis for ISPs serve as the major mechanism to deal with and investigate real-life scenarios.

@incollection{info3-incollection-2013-20, abstract = {The Internet has seen a strong move to support overlay applications, which demand a coherent and integrated control in underlying heterogeneous networks in a scalable, resilient, and energy-efficient manner. A tighter integration of network management and overlay service functionality can lead to cross-layer optimization of operations and management, which is a promising approach as it offers a large business potential in operational perspectives for all players involved. Therefore, the objective of this paper is to present SmartenIT (Socially-aware Management of New Overlay Application Traffic combined with Energy Efficiency in the Internet), which targets at an incentive-compatible cross-layer network management for providers of overlay-based application (e.g., cloud applications, content delivery, and social networks), network providers, and end-users. The goal is to ensure a QoE-awareness, by addressing accordingly load and traffic patterns or special application requirements, and exploiting at the same time social awareness (in terms of user relations and interests). Moreover, energy efficiency with respect to both end-user devices and underlying networking infrastructure is tackled to ensure an operationally efficient management. Incentive-compatible network management mechanisms for improving metrics on an inter-domain basis for ISPs serve as the major mechanism to deal with and investigate real-life scenarios.}, author = {Stiller, Burkhard and Hausheer, David and Hoßfeld, Tobias}, booktitle = {The Future Internet}, editor = {Alex Galis, Anastasius Gavras}, keywords = {smartenit}, month = 4, publisher = {Springer, LNCS 7858}, title = {Towards a Socially-Aware Management of New Overlay Application Traffic Combined with Energy Efficiency in the Internet (SmartenIT)}, year = 2013 }

%0 Book Section %1 info3-incollection-2013-20 %A Stiller, Burkhard %A Hausheer, David %A Hoßfeld, Tobias %B The Future Internet %D 2013 %E Alex Galis, Anastasius Gavras %I Springer, LNCS 7858 %T Towards a Socially-Aware Management of New Overlay Application Traffic Combined with Energy Efficiency in the Internet (SmartenIT) %X The Internet has seen a strong move to support overlay applications, which demand a coherent and integrated control in underlying heterogeneous networks in a scalable, resilient, and energy-efficient manner. A tighter integration of network management and overlay service functionality can lead to cross-layer optimization of operations and management, which is a promising approach as it offers a large business potential in operational perspectives for all players involved. Therefore, the objective of this paper is to present SmartenIT (Socially-aware Management of New Overlay Application Traffic combined with Energy Efficiency in the Internet), which targets at an incentive-compatible cross-layer network management for providers of overlay-based application (e.g., cloud applications, content delivery, and social networks), network providers, and end-users. The goal is to ensure a QoE-awareness, by addressing accordingly load and traffic patterns or special application requirements, and exploiting at the same time social awareness (in terms of user relations and interests). Moreover, energy efficiency with respect to both end-user devices and underlying networking infrastructure is tackled to ensure an operationally efficient management. Incentive-compatible network management mechanisms for improving metrics on an inter-domain basis for ISPs serve as the major mechanism to deal with and investigate real-life scenarios.
Aktuelle Entwicklungen im Internet und sich daraus ergebende rechtliche Fragestellungen Hoßfeld, Tobias in Internet-Kriminalität und die neuen Herausforderungen der Informationsgesellschaft des 21. Jahrhundert, E. H. {Jiri Herczeg (ed.) (2011).
- [ Abstract ]
- [ BibTeX ]
- [ EndNote ]
Das Internet verändert und entwickelt sich stets weiter. Dabei führen neue Paradigmen wie P2P oder Web 2.0 zu neuartigen Diensten und Applikationen, die allerdings ebenso neuartige technische aber auch rechtliche Problemstellungen nach sich ziehen. In diesem Zusammenhang wurden bei den P2P Anwendungen die Dateitauschbörsen, P2P-basierte Videostreaming Anwendungen sowie die Skype Internettelefonie diskutiert. Bei der Anwendung des Web 2.0 Paradigmas lag der Schwerpunkt auf den sozialen Netzwerken im Internet und dem Crowdsourcing als neue Form der Arbeitsauslagerung. Es wurde auf existierende soziale Netzwerke, die Verbesserung von Internet-Diensten und neuartige Geschäftsmodelle durch sozialen Netzwerke, sowie der Integration der Präsenz der Nutzer in neue soziale Netzwerkanwendungen eingegangen. Weiterhin wurden auf die technischen Veränderungen des Internets durch Virtualisierung und durch Economic Traffic Management zur Steuerung des Datenverkehrs im Internet eingegangen. Die sich aus diesen Veränderungen im Internet ergebenden neuartigen rechtlichen Fragestellungen können wie folgt stichpunktartig zusammengefasst werden. 1) P2P Anwendungen: - Einsatz von Pollution/Poisoining nach Einführung der Kulturflatrate, um Verkauf von digitalen Inhalten voranzutreiben; - Rechtliche Unterschiede zwischen Video-on-Demand und Livestreaming Plattformen; - Rechner leitet ohne das Wissen des Nutzers urheberrechtlich geschützte Inhalte weiter. 2) Soziale Netzwerke: - Manipulation der Wichtigkeit und Korrektheit von Nachrichten; - Schutz der Privatsphäre von Nutzern und Bewusstseinsschaffung für Verfügbarkeit von Daten im Internet; - Gefälschte Identitäten von OSN Nutzern, um falsche Informationen zu streuen oder um an private Daten fremder Nutzer zu gelangen; - Ausspionieren des sozialen Profils eines Nutzers durch Computerprogramme und Bots; - Identifizieren eines Nutzers beim Surfen auf beliebigen Webseiten. 3) Crowdsourcing: - Suchmaschinenoptimierung durch Routine Tasks; - Löschen von Informationen durch Überfluten des Internet mit generierten Inhalten; - Rechteübertragung bei kreativen Tasks. 4) Virtualisierung: - Physikalische Lokation eines Nutzers nicht identifizierbar; - Verantwortlichkeit bei der Vorratsdatenspeicherung. 5) Economic Traffic Management: - Netzneutralität im Widerspruch zu Lösungsansätzen.

@incollection{info3-incollection-2011-14, abstract = {Das Internet verändert und entwickelt sich stets weiter. Dabei führen neue Paradigmen wie P2P oder Web 2.0 zu neuartigen Diensten und Applikationen, die allerdings ebenso neuartige technische aber auch rechtliche Problemstellungen nach sich ziehen. In diesem Zusammenhang wurden bei den P2P Anwendungen die Dateitauschbörsen, P2P-basierte Videostreaming Anwendungen sowie die Skype Internettelefonie diskutiert. Bei der Anwendung des Web 2.0 Paradigmas lag der Schwerpunkt auf den sozialen Netzwerken im Internet und dem Crowdsourcing als neue Form der Arbeitsauslagerung. Es wurde auf existierende soziale Netzwerke, die Verbesserung von Internet-Diensten und neuartige Geschäftsmodelle durch sozialen Netzwerke, sowie der Integration der Präsenz der Nutzer in neue soziale Netzwerkanwendungen eingegangen. Weiterhin wurden auf die technischen Veränderungen des Internets durch Virtualisierung und durch Economic Traffic Management zur Steuerung des Datenverkehrs im Internet eingegangen. Die sich aus diesen Veränderungen im Internet ergebenden neuartigen rechtlichen Fragestellungen können wie folgt stichpunktartig zusammengefasst werden. 1) P2P Anwendungen: - Einsatz von Pollution/Poisoining nach Einführung der Kulturflatrate, um Verkauf von digitalen Inhalten voranzutreiben; - Rechtliche Unterschiede zwischen Video-on-Demand und Livestreaming Plattformen; - Rechner leitet ohne das Wissen des Nutzers urheberrechtlich geschützte Inhalte weiter. 2) Soziale Netzwerke: - Manipulation der Wichtigkeit und Korrektheit von Nachrichten; - Schutz der Privatsphäre von Nutzern und Bewusstseinsschaffung für Verfügbarkeit von Daten im Internet; - Gefälschte Identitäten von OSN Nutzern, um falsche Informationen zu streuen oder um an private Daten fremder Nutzer zu gelangen; - Ausspionieren des sozialen Profils eines Nutzers durch Computerprogramme und Bots; - Identifizieren eines Nutzers beim Surfen auf beliebigen Webseiten. 3) Crowdsourcing: - Suchmaschinenoptimierung durch Routine Tasks; - Löschen von Informationen durch Überfluten des Internet mit generierten Inhalten; - Rechteübertragung bei kreativen Tasks. 4) Virtualisierung: - Physikalische Lokation eines Nutzers nicht identifizierbar; - Verantwortlichkeit bei der Vorratsdatenspeicherung. 5) Economic Traffic Management: - Netzneutralität im Widerspruch zu Lösungsansätzen.}, author = {Hoßfeld, Tobias}, booktitle = {Internet-Kriminalität und die neuen Herausforderungen der Informationsgesellschaft des 21. Jahrhundert}, editor = {{Jiri Herczeg, Eric Hilgendorf}, Tomas Grivna}, keywords = {myown}, month = 1, publisher = {Wolters Kluwer CR, ISBN 978-80-7357-601-1}, title = {Aktuelle Entwicklungen im Internet und sich daraus ergebende rechtliche Fragestellungen}, year = 2011 }

%0 Book Section %1 info3-incollection-2011-14 %A Hoßfeld, Tobias %B Internet-Kriminalität und die neuen Herausforderungen der Informationsgesellschaft des 21. Jahrhundert %D 2011 %E {Jiri Herczeg, Eric Hilgendorf} %I Wolters Kluwer CR, ISBN 978-80-7357-601-1 %T Aktuelle Entwicklungen im Internet und sich daraus ergebende rechtliche Fragestellungen %X Das Internet verändert und entwickelt sich stets weiter. Dabei führen neue Paradigmen wie P2P oder Web 2.0 zu neuartigen Diensten und Applikationen, die allerdings ebenso neuartige technische aber auch rechtliche Problemstellungen nach sich ziehen. In diesem Zusammenhang wurden bei den P2P Anwendungen die Dateitauschbörsen, P2P-basierte Videostreaming Anwendungen sowie die Skype Internettelefonie diskutiert. Bei der Anwendung des Web 2.0 Paradigmas lag der Schwerpunkt auf den sozialen Netzwerken im Internet und dem Crowdsourcing als neue Form der Arbeitsauslagerung. Es wurde auf existierende soziale Netzwerke, die Verbesserung von Internet-Diensten und neuartige Geschäftsmodelle durch sozialen Netzwerke, sowie der Integration der Präsenz der Nutzer in neue soziale Netzwerkanwendungen eingegangen. Weiterhin wurden auf die technischen Veränderungen des Internets durch Virtualisierung und durch Economic Traffic Management zur Steuerung des Datenverkehrs im Internet eingegangen. Die sich aus diesen Veränderungen im Internet ergebenden neuartigen rechtlichen Fragestellungen können wie folgt stichpunktartig zusammengefasst werden. 1) P2P Anwendungen: - Einsatz von Pollution/Poisoining nach Einführung der Kulturflatrate, um Verkauf von digitalen Inhalten voranzutreiben; - Rechtliche Unterschiede zwischen Video-on-Demand und Livestreaming Plattformen; - Rechner leitet ohne das Wissen des Nutzers urheberrechtlich geschützte Inhalte weiter. 2) Soziale Netzwerke: - Manipulation der Wichtigkeit und Korrektheit von Nachrichten; - Schutz der Privatsphäre von Nutzern und Bewusstseinsschaffung für Verfügbarkeit von Daten im Internet; - Gefälschte Identitäten von OSN Nutzern, um falsche Informationen zu streuen oder um an private Daten fremder Nutzer zu gelangen; - Ausspionieren des sozialen Profils eines Nutzers durch Computerprogramme und Bots; - Identifizieren eines Nutzers beim Surfen auf beliebigen Webseiten. 3) Crowdsourcing: - Suchmaschinenoptimierung durch Routine Tasks; - Löschen von Informationen durch Überfluten des Internet mit generierten Inhalten; - Rechteübertragung bei kreativen Tasks. 4) Virtualisierung: - Physikalische Lokation eines Nutzers nicht identifizierbar; - Verantwortlichkeit bei der Vorratsdatenspeicherung. 5) Economic Traffic Management: - Netzneutralität im Widerspruch zu Lösungsansätzen.
Chapter VII: Cooperation Strategies for P2P Content Distribution in Cellular Mobile Networks: Considering Selfishness and Heterogeneity Hoßfeld, Tobias; Schlosser, Daniel; Tutschku, Kurt; Tran-Gia, Phuoc in Mobile Peer-to-Peer Computing for Next Generation Distributed Environments: Advancing Conceptual and Algorithmic Applications, B.-C. Seet (ed.) (2009).
- [ Abstract ]
- [ BibTeX ]
- [ EndNote ]
The performance of P2P content distribution in cellular networks depends highly on the cooperation and coordination of heterogeneous and often selfish mobile users. The major challenges are the identification of problems specifically arising in cellular mobile networks and the development of new cooperation strategies to overcome these problems. In this chapter, we review common cooperation strategies using multi-source downloads. We demonstrate the fundamental “last chunk” problem of typical strategies as used by eDonkey or BitTorrent. This is caused by the selfishness of users; however, an ordered chunk delivery evades this problem. In the coherent, subsequent chapter “Cooperation Strategies for P2P Content Distribution in Cellular Mobile Networks: Considering Mobility and Heterogeneity”, the impact of mobility and vertical handover between heterogeneous wireless access technologies is investigated.

@incollection{info3-incollection-2009-9, abstract = {The performance of P2P content distribution in cellular networks depends highly on the cooperation and coordination of heterogeneous and often selfish mobile users. The major challenges are the identification of problems specifically arising in cellular mobile networks and the development of new cooperation strategies to overcome these problems. In this chapter, we review common cooperation strategies using multi-source downloads. We demonstrate the fundamental “last chunk” problem of typical strategies as used by eDonkey or BitTorrent. This is caused by the selfishness of users; however, an ordered chunk delivery evades this problem. In the coherent, subsequent chapter “Cooperation Strategies for P2P Content Distribution in Cellular Mobile Networks: Considering Mobility and Heterogeneity”, the impact of mobility and vertical handover between heterogeneous wireless access technologies is investigated.}, author = {Hoßfeld, Tobias and Schlosser, Daniel and Tutschku, Kurt and Tran-Gia, Phuoc}, booktitle = {Mobile Peer-to-Peer Computing for Next Generation Distributed Environments: Advancing Conceptual and Algorithmic Applications}, editor = {Seet, Boon-Chong}, keywords = {myown}, month = 5, publisher = {Information Science Reference, ISBN: 978-1-60566-715-7}, title = {Chapter VII: Cooperation Strategies for P2P Content Distribution in Cellular Mobile Networks: Considering Selfishness and Heterogeneity}, year = 2009 }

%0 Book Section %1 info3-incollection-2009-9 %A Hoßfeld, Tobias %A Schlosser, Daniel %A Tutschku, Kurt %A Tran-Gia, Phuoc %B Mobile Peer-to-Peer Computing for Next Generation Distributed Environments: Advancing Conceptual and Algorithmic Applications %D 2009 %E Seet, Boon-Chong %I Information Science Reference, ISBN: 978-1-60566-715-7 %T Chapter VII: Cooperation Strategies for P2P Content Distribution in Cellular Mobile Networks: Considering Selfishness and Heterogeneity %X The performance of P2P content distribution in cellular networks depends highly on the cooperation and coordination of heterogeneous and often selfish mobile users. The major challenges are the identification of problems specifically arising in cellular mobile networks and the development of new cooperation strategies to overcome these problems. In this chapter, we review common cooperation strategies using multi-source downloads. We demonstrate the fundamental “last chunk” problem of typical strategies as used by eDonkey or BitTorrent. This is caused by the selfishness of users; however, an ordered chunk delivery evades this problem. In the coherent, subsequent chapter “Cooperation Strategies for P2P Content Distribution in Cellular Mobile Networks: Considering Mobility and Heterogeneity”, the impact of mobility and vertical handover between heterogeneous wireless access technologies is investigated.
An Economic Traffic Management Approach to Enable the TripleWin for Users, ISPs, and Overlay Providers Hoßfeld, Tobias; Hausheer, David; Hecht, Fabio; Lehrieder, Frank; Oechsner, Simon; Papafili, Ioanna; Racz, Peter; Soursos, Sergios; Staehle, Dirk; Stamoulis, George D.; Tran-Gia, Phuoc; Stiller, Burkhard in FIA Prague Book, ISBN 978-1-60750-007-0, G. Tselentis, J. Domingue, A. Galis, A. Gavras, D. Hausheer, S. Krco, V. Lotz, T. Zahariadis (eds.) (2009).
- [ Abstract ]
- [ BibTeX ]
- [ EndNote ]
Socio-economic aspects play an increasingly important role in the Future Internet. To enable a TripleWin situation for the involved players, i.e. the end users, the ISPs and telecommunication operators, and the service providers, a new, incentive-based concept is proposed referred to as Economic Traffic Management (ETM). It aims at reducing costs within the network while improving the Quality-of-Experience (QoE) for end users. In particular, peer-to-peer (P2P) overlay applications generate a large amount of costs due to inter-domain traffic. ETM solution approaches have to take into account (a) the traffic patterns stemming from the overlay application, (b) the charging models for transit traffic, and (c) the applicability and efficiency of the proposed solution. The complex interaction between these three components and its consequences is demonstrated on selected examples. As a result it is shown that different ETM approaches have to be combined for an overall solution. To this end, the paper derives functional and non-functional requirements for designing ETM and provides a suitable architecture enabling the implementation of a TripleWin solution.

@incollection{info3-incollection-2009-12, abstract = {Socio-economic aspects play an increasingly important role in the Future Internet. To enable a TripleWin situation for the involved players, i.e. the end users, the ISPs and telecommunication operators, and the service providers, a new, incentive-based concept is proposed referred to as Economic Traffic Management (ETM). It aims at reducing costs within the network while improving the Quality-of-Experience (QoE) for end users. In particular, peer-to-peer (P2P) overlay applications generate a large amount of costs due to inter-domain traffic. ETM solution approaches have to take into account (a) the traffic patterns stemming from the overlay application, (b) the charging models for transit traffic, and (c) the applicability and efficiency of the proposed solution. The complex interaction between these three components and its consequences is demonstrated on selected examples. As a result it is shown that different ETM approaches have to be combined for an overall solution. To this end, the paper derives functional and non-functional requirements for designing ETM and provides a suitable architecture enabling the implementation of a TripleWin solution.}, author = {Hoßfeld, Tobias and Hausheer, David and Hecht, Fabio and Lehrieder, Frank and Oechsner, Simon and Papafili, Ioanna and Racz, Peter and Soursos, Sergios and Staehle, Dirk and Stamoulis, George D. and Tran-Gia, Phuoc and Stiller, Burkhard}, booktitle = {FIA Prague Book, ISBN 978-1-60750-007-0}, editor = {Tselentis, Georgios and Domingue, John and Galis, Alex and Gavras, Anastasius and Hausheer, David and Krco, Srdjan and Lotz, Volkmar and Zahariadis, Theodore}, keywords = {myown}, month = 5, publisher = {IOS Press Books Online}, title = {An Economic Traffic Management Approach to Enable the TripleWin for Users, ISPs, and Overlay Providers}, year = 2009 }

%0 Book Section %1 info3-incollection-2009-12 %A Hoßfeld, Tobias %A Hausheer, David %A Hecht, Fabio %A Lehrieder, Frank %A Oechsner, Simon %A Papafili, Ioanna %A Racz, Peter %A Soursos, Sergios %A Staehle, Dirk %A Stamoulis, George D. %A Tran-Gia, Phuoc %A Stiller, Burkhard %B FIA Prague Book, ISBN 978-1-60750-007-0 %D 2009 %E Tselentis, Georgios %E Domingue, John %E Galis, Alex %E Gavras, Anastasius %E Hausheer, David %E Krco, Srdjan %E Lotz, Volkmar %E Zahariadis, Theodore %I IOS Press Books Online %T An Economic Traffic Management Approach to Enable the TripleWin for Users, ISPs, and Overlay Providers %X Socio-economic aspects play an increasingly important role in the Future Internet. To enable a TripleWin situation for the involved players, i.e. the end users, the ISPs and telecommunication operators, and the service providers, a new, incentive-based concept is proposed referred to as Economic Traffic Management (ETM). It aims at reducing costs within the network while improving the Quality-of-Experience (QoE) for end users. In particular, peer-to-peer (P2P) overlay applications generate a large amount of costs due to inter-domain traffic. ETM solution approaches have to take into account (a) the traffic patterns stemming from the overlay application, (b) the charging models for transit traffic, and (c) the applicability and efficiency of the proposed solution. The complex interaction between these three components and its consequences is demonstrated on selected examples. As a result it is shown that different ETM approaches have to be combined for an overall solution. To this end, the paper derives functional and non-functional requirements for designing ETM and provides a suitable architecture enabling the implementation of a TripleWin solution.
Chapter XVI: Mobile P2P in Cellular Mobile Networks: Architecture and Performance Tutschku, Kurt; Berl, Andreas; Hoßfeld, Tobias; de Meer, Hermann in Mobile Peer-to-Peer Computing for Next Generation Distributed Environments: Advancing Conceptual and Algorithmic Applications, B.-C. Seet (ed.) (2009).
- [ Abstract ]
- [ BibTeX ]
- [ EndNote ]
Telecommunication has seen recently two areas with very high growth rates: cellular networks, e.g. GSM (Global System for Mobile Communications) or UMTS (Universal Mobile Telecommunications System), and P2P (Peer-to-Peer) file-sharing applications. A combination of both might be highly attractive, a) for attracting new users and b) for exploiting the potential of cellular broadband technologies. From a system's perspective, architectures and performance figures of cellular mobile network applications and services that have edge-based intelligence (e.g. P2P applications) are to the best of our knowledge less researched and many questions remain open. This chapter presents the design of MP2P (Mobile P2P) applications for cellular mobile networks by using the example of a MP2P content-distribution application. First, the incompatibilities between the P2P paradigm and properties of cellular mobile networks are identified. Then, a design methodology for MP2P applications for cellular mobile networks is proposed. The proposed method is based on a functional analysis of the two basic P2P functions, resource mediation and resource access control. The result is a hybrid P2P content-distribution architecture, which is enhanced by different operator-controlled infrastructure elements. The suggested architecture does not only overcome incompatibilities between P2P and cellular mobile communication systems, it also meets functional needs and performance requirements of future P2P applications in cellular environments and preserves largely the user characteristics and efficiency of P2P systems. Finally, the performance enhancements by the architecture for the two basic P2P functions are investigated by comprehensive simulative and analytical performance evaluations.

@incollection{info3-incollection-2009-11, abstract = {Telecommunication has seen recently two areas with very high growth rates: cellular networks, e.g. GSM (Global System for Mobile Communications) or UMTS (Universal Mobile Telecommunications System), and P2P (Peer-to-Peer) file-sharing applications. A combination of both might be highly attractive, a) for attracting new users and b) for exploiting the potential of cellular broadband technologies. From a system's perspective, architectures and performance figures of cellular mobile network applications and services that have edge-based intelligence (e.g. P2P applications) are to the best of our knowledge less researched and many questions remain open. This chapter presents the design of MP2P (Mobile P2P) applications for cellular mobile networks by using the example of a MP2P content-distribution application. First, the incompatibilities between the P2P paradigm and properties of cellular mobile networks are identified. Then, a design methodology for MP2P applications for cellular mobile networks is proposed. The proposed method is based on a functional analysis of the two basic P2P functions, resource mediation and resource access control. The result is a hybrid P2P content-distribution architecture, which is enhanced by different operator-controlled infrastructure elements. The suggested architecture does not only overcome incompatibilities between P2P and cellular mobile communication systems, it also meets functional needs and performance requirements of future P2P applications in cellular environments and preserves largely the user characteristics and efficiency of P2P systems. Finally, the performance enhancements by the architecture for the two basic P2P functions are investigated by comprehensive simulative and analytical performance evaluations.}, author = {Tutschku, Kurt and Berl, Andreas and Hoßfeld, Tobias and de Meer, Hermann}, booktitle = {Mobile Peer-to-Peer Computing for Next Generation Distributed Environments: Advancing Conceptual and Algorithmic Applications}, editor = {Seet, Boon-Chong}, keywords = {myown}, month = 5, publisher = {Information Science Reference, ISBN: 978-1-60566-715-7}, title = {Chapter XVI: Mobile P2P in Cellular Mobile Networks: Architecture and Performance}, year = 2009 }

%0 Book Section %1 info3-incollection-2009-11 %A Tutschku, Kurt %A Berl, Andreas %A Hoßfeld, Tobias %A de Meer, Hermann %B Mobile Peer-to-Peer Computing for Next Generation Distributed Environments: Advancing Conceptual and Algorithmic Applications %D 2009 %E Seet, Boon-Chong %I Information Science Reference, ISBN: 978-1-60566-715-7 %T Chapter XVI: Mobile P2P in Cellular Mobile Networks: Architecture and Performance %X Telecommunication has seen recently two areas with very high growth rates: cellular networks, e.g. GSM (Global System for Mobile Communications) or UMTS (Universal Mobile Telecommunications System), and P2P (Peer-to-Peer) file-sharing applications. A combination of both might be highly attractive, a) for attracting new users and b) for exploiting the potential of cellular broadband technologies. From a system's perspective, architectures and performance figures of cellular mobile network applications and services that have edge-based intelligence (e.g. P2P applications) are to the best of our knowledge less researched and many questions remain open. This chapter presents the design of MP2P (Mobile P2P) applications for cellular mobile networks by using the example of a MP2P content-distribution application. First, the incompatibilities between the P2P paradigm and properties of cellular mobile networks are identified. Then, a design methodology for MP2P applications for cellular mobile networks is proposed. The proposed method is based on a functional analysis of the two basic P2P functions, resource mediation and resource access control. The result is a hybrid P2P content-distribution architecture, which is enhanced by different operator-controlled infrastructure elements. The suggested architecture does not only overcome incompatibilities between P2P and cellular mobile communication systems, it also meets functional needs and performance requirements of future P2P applications in cellular environments and preserves largely the user characteristics and efficiency of P2P systems. Finally, the performance enhancements by the architecture for the two basic P2P functions are investigated by comprehensive simulative and analytical performance evaluations.
Chapter VIII: Cooperation Strategies for P2P Content Distribution in Cellular Mobile Networks: Considering Mobility and Heterogeneity Hoßfeld, Tobias; Duelli, Michael; Staehle, Dirk; Tran-Gia, Phuoc in Mobile Peer-to-Peer Computing for Next Generation Distributed Environments: Advancing Conceptual and Algorithmic Applications, B.-C. Seet (ed.) (2009). 1234–5678.
- [ Abstract ]
- [ BibTeX ]
- [ EndNote ]
The performance of P2P content distribution in cellular networks depends highly on the cooperation and coordination of heterogeneous and often selfish mobile users. The major challenges are the identification of problems specifically arising in cellular mobile networks and the development of new cooperation strategies to overcome these problems. In the coherent previous chapter, we focused on the selfishness of users in such heterogeneous environments. This discussion is now extended by emphasizing the impact of mobility and vertical handover between different wireless access technologies. An abstract mobility model is required to allow the performance evaluation in feasible computational time. As a result, the performance in today’s and future cellular networks is predicted and new approaches to master heterogeneity in cellular networks are derived.

@incollection{info3-incollection-2009-10, abstract = {The performance of P2P content distribution in cellular networks depends highly on the cooperation and coordination of heterogeneous and often selfish mobile users. The major challenges are the identification of problems specifically arising in cellular mobile networks and the development of new cooperation strategies to overcome these problems. In the coherent previous chapter, we focused on the selfishness of users in such heterogeneous environments. This discussion is now extended by emphasizing the impact of mobility and vertical handover between different wireless access technologies. An abstract mobility model is required to allow the performance evaluation in feasible computational time. As a result, the performance in today’s and future cellular networks is predicted and new approaches to master heterogeneity in cellular networks are derived.}, author = {Hoßfeld, Tobias and Duelli, Michael and Staehle, Dirk and Tran-Gia, Phuoc}, booktitle = {Mobile Peer-to-Peer Computing for Next Generation Distributed Environments: Advancing Conceptual and Algorithmic Applications}, editor = {Seet, Boon-Chong}, keywords = {myown}, month = 5, pages = {1234–5678}, publisher = {Information Science Reference, ISBN: 978-1-60566-715-7}, title = {Chapter VIII: Cooperation Strategies for P2P Content Distribution in Cellular Mobile Networks: Considering Mobility and Heterogeneity}, year = 2009 }

%0 Book Section %1 info3-incollection-2009-10 %A Hoßfeld, Tobias %A Duelli, Michael %A Staehle, Dirk %A Tran-Gia, Phuoc %B Mobile Peer-to-Peer Computing for Next Generation Distributed Environments: Advancing Conceptual and Algorithmic Applications %D 2009 %E Seet, Boon-Chong %I Information Science Reference, ISBN: 978-1-60566-715-7 %P 1234--5678 %T Chapter VIII: Cooperation Strategies for P2P Content Distribution in Cellular Mobile Networks: Considering Mobility and Heterogeneity %X The performance of P2P content distribution in cellular networks depends highly on the cooperation and coordination of heterogeneous and often selfish mobile users. The major challenges are the identification of problems specifically arising in cellular mobile networks and the development of new cooperation strategies to overcome these problems. In the coherent previous chapter, we focused on the selfishness of users in such heterogeneous environments. This discussion is now extended by emphasizing the impact of mobility and vertical handover between different wireless access technologies. An abstract mobility model is required to allow the performance evaluation in feasible computational time. As a result, the performance in today’s and future cellular networks is predicted and new approaches to master heterogeneity in cellular networks are derived.
Warum Panini Fußballalben auch Informatikern Spaß machen Binzenhöfer, Andreas; Hoßfeld, Tobias in Fußball eine Wissenschaft für sich, P. D. H.-G. Weigand (ed.) (2006).
- [ Abstract ]
- [ BibTeX ]
- [ EndNote ]
Alle vier Jahre fiebern Fußballfans rund um den Globus der Weltmeisterschaft in ihrem Lieblingssport entgegen. Nachdem das Großereignis dieses Jahr im eigenen Land stattfindet, ist die Vorfreude hierzulande natürlich besonders groß. Selbstverständlich lässt das Spektakel auch den Informatiker nicht unberührt. Kein Wunder, handelt es sich doch um den perfekten Sport für einen Naturwissenschaftler. Man kann sich auf die Couch vor ein technisches Gerät setzen und anderen Menschen zusehen, wie sich diese physisch verausgaben. Das Beste dabei, man braucht noch nicht einmal raus an die frische Luft. Nun sind aber gerade die letzten Monate vor dem Anpfiff des Eröffnungsspiels vor Spannung kaum zu ertragen. Doch zum Glück hatte die Firma Panini vor vielen Jahren die glorreiche Idee, das Konterfei der großen Fußballstars auf Sticker zu drucken und nebst Sammelalben zu verkaufen. Solche Sammelalben gibt es mittlerweile für fast alles was das Kinderherz begehrt, aber eben auch für erwachsene Themen wie die Fußballweltmeisterschaft 2006. Auch unser Informatiker beschließt, sich ein solches Album zuzulegen und bis zum Beginn der Weltmeisterschaft mit seinen sportlichen Idolen aufzufüllen...

@incollection{info3-incollection-2006-5, abstract = {Alle vier Jahre fiebern Fußballfans rund um den Globus der Weltmeisterschaft in ihrem Lieblingssport entgegen. Nachdem das Großereignis dieses Jahr im eigenen Land stattfindet, ist die Vorfreude hierzulande natürlich besonders groß. Selbstverständlich lässt das Spektakel auch den Informatiker nicht unberührt. Kein Wunder, handelt es sich doch um den perfekten Sport für einen Naturwissenschaftler. Man kann sich auf die Couch vor ein technisches Gerät setzen und anderen Menschen zusehen, wie sich diese physisch verausgaben. Das Beste dabei, man braucht noch nicht einmal raus an die frische Luft. Nun sind aber gerade die letzten Monate vor dem Anpfiff des Eröffnungsspiels vor Spannung kaum zu ertragen. Doch zum Glück hatte die Firma Panini vor vielen Jahren die glorreiche Idee, das Konterfei der großen Fußballstars auf Sticker zu drucken und nebst Sammelalben zu verkaufen. Solche Sammelalben gibt es mittlerweile für fast alles was das Kinderherz begehrt, aber eben auch für erwachsene Themen wie die Fußballweltmeisterschaft 2006. Auch unser Informatiker beschließt, sich ein solches Album zuzulegen und bis zum Beginn der Weltmeisterschaft mit seinen sportlichen Idolen aufzufüllen...}, author = {Binzenhöfer, Andreas and Hoßfeld, Tobias}, booktitle = {Fußball eine Wissenschaft für sich}, editor = {Weigand, Prof. Dr. Hans-Georg}, keywords = {myown}, month = 4, publisher = {Verlag Königshausen & Neumann}, title = {Warum Panini Fußballalben auch Informatikern Spaß machen}, year = 2006 }

%0 Book Section %1 info3-incollection-2006-5 %A Binzenhöfer, Andreas %A Hoßfeld, Tobias %B Fußball eine Wissenschaft für sich %D 2006 %E Weigand, Prof. Dr. Hans-Georg %I Verlag Königshausen & Neumann %T Warum Panini Fußballalben auch Informatikern Spaß machen %X Alle vier Jahre fiebern Fußballfans rund um den Globus der Weltmeisterschaft in ihrem Lieblingssport entgegen. Nachdem das Großereignis dieses Jahr im eigenen Land stattfindet, ist die Vorfreude hierzulande natürlich besonders groß. Selbstverständlich lässt das Spektakel auch den Informatiker nicht unberührt. Kein Wunder, handelt es sich doch um den perfekten Sport für einen Naturwissenschaftler. Man kann sich auf die Couch vor ein technisches Gerät setzen und anderen Menschen zusehen, wie sich diese physisch verausgaben. Das Beste dabei, man braucht noch nicht einmal raus an die frische Luft. Nun sind aber gerade die letzten Monate vor dem Anpfiff des Eröffnungsspiels vor Spannung kaum zu ertragen. Doch zum Glück hatte die Firma Panini vor vielen Jahren die glorreiche Idee, das Konterfei der großen Fußballstars auf Sticker zu drucken und nebst Sammelalben zu verkaufen. Solche Sammelalben gibt es mittlerweile für fast alles was das Kinderherz begehrt, aber eben auch für erwachsene Themen wie die Fußballweltmeisterschaft 2006. Auch unser Informatiker beschließt, sich ein solches Album zuzulegen und bis zum Beginn der Weltmeisterschaft mit seinen sportlichen Idolen aufzufüllen...

Inproceedings[ to top ]

Discrete-Time Analysis of Multi-Component Queuing Networks under Renewal Approximation Geißler, Stefan; Lange, Stanislav; Hasslinger, Gerhard; Tran-Gia, Phuoc; Hoßfeld, Tobias in 34th International Teletraffic Congress (ITC). Shenzhen, China (2023).
- [ BibTeX ]
- [ EndNote ]
@inproceedings{info3-inproceedings-2023-1, author = {Geißler, Stefan and Lange, Stanislav and Hasslinger, Gerhard and Tran-Gia, Phuoc and Hoßfeld, Tobias}, booktitle = {34th International Teletraffic Congress (ITC). Shenzhen, China}, keywords = {sys:hidden:inproceedings}, month = 9, title = {Discrete-Time Analysis of Multi-Component Queuing Networks under Renewal Approximation}, year = 2023 }

%0 Conference Paper %1 info3-inproceedings-2023-1 %A Geißler, Stefan %A Lange, Stanislav %A Hasslinger, Gerhard %A Tran-Gia, Phuoc %A Hoßfeld, Tobias %B 34th International Teletraffic Congress (ITC). Shenzhen, China %D 2023 %T Discrete-Time Analysis of Multi-Component Queuing Networks under Renewal Approximation
Moving Down the Stack: Performance Evaluation of Packet Processing Technologies for Stateful Firewalls Dietz, Katharina; Gray, Nicholas; Wolz, Manuel; Lorenz, Claas; Hoßfeld, Tobias; Seufert, Michael in 34th IEEE/IFIP Network Operations and Management Symposium (NOMS) (2023).
- [ BibTeX ]
- [ EndNote ]
@inproceedings{info3-inproceedings-2023-2, address = {Miami, Florida}, author = {Dietz, Katharina and Gray, Nicholas and Wolz, Manuel and Lorenz, Claas and Hoßfeld, Tobias and Seufert, Michael}, booktitle = {34th IEEE/IFIP Network Operations and Management Symposium (NOMS)}, keywords = {ucn}, month = 5, title = {Moving Down the Stack: Performance Evaluation of Packet Processing Technologies for Stateful Firewalls}, year = 2023 }

%0 Conference Paper %1 info3-inproceedings-2023-2 %A Dietz, Katharina %A Gray, Nicholas %A Wolz, Manuel %A Lorenz, Claas %A Hoßfeld, Tobias %A Seufert, Michael %B 34th IEEE/IFIP Network Operations and Management Symposium (NOMS) %C Miami, Florida %D 2023 %T Moving Down the Stack: Performance Evaluation of Packet Processing Technologies for Stateful Firewalls
Not all Web Pages are Born the Same. Content Tailored Learning for Web QoE Inference Casas, Pedro; Wassermann, Sarah; Wehner, Nikolas; Seufert, Michael; Hoßfeld, Tobias in IEEE International Symposium on Measurements & Networking (M&N 2022) (2022).
- [ Abstract ]
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Web Quality of Experience (QoE) monitoring is a critical task for Internet Service Providers (ISPs), especially due to the key role played by customer experience in churn management. Previously, we have tackled the problem of Web QoE inference from the ISP perspective, relying on passive measurement of encrypted network traffic and machine learning models. In this paper, we exploit the broad heterogeneity of contents embedded in web pages to improve the state of the art performance in Web QoE inference, relying on web-content learning model tailoring. By analyzing the top-500 most popular web pages of the Internet through unsupervised learning, we discover different web page content classes which realize significantly different Web QoE inference performance. We train supervised learning inference models separately for each of these classes, using the well-known Speed Index (SI) metric as proxy to Web QoE. Empirical evaluations on a large corpus of Web QoE measurements for top popular websites demonstrate that our combined content-tailored approach improves the inference performance of the SI by almost 30% with respect to previous single-model approaches, reducing the QoE inference error in terms of mean opinion scores by more than 40%.

@inproceedings{info3-inproceedings-2022-10, abstract = {Web Quality of Experience (QoE) monitoring is a critical task for Internet Service Providers (ISPs), especially due to the key role played by customer experience in churn management. Previously, we have tackled the problem of Web QoE inference from the ISP perspective, relying on passive measurement of encrypted network traffic and machine learning models. In this paper, we exploit the broad heterogeneity of contents embedded in web pages to improve the state of the art performance in Web QoE inference, relying on web-content learning model tailoring. By analyzing the top-500 most popular web pages of the Internet through unsupervised learning, we discover different web page content classes which realize significantly different Web QoE inference performance. We train supervised learning inference models separately for each of these classes, using the well-known Speed Index (SI) metric as proxy to Web QoE. Empirical evaluations on a large corpus of Web QoE measurements for top popular websites demonstrate that our combined content-tailored approach improves the inference performance of the SI by almost 30% with respect to previous single-model approaches, reducing the QoE inference error in terms of mean opinion scores by more than 40%.}, author = {Casas, Pedro and Wassermann, Sarah and Wehner, Nikolas and Seufert, Michael and Hoßfeld, Tobias}, booktitle = {IEEE International Symposium on Measurements & Networking (M&N 2022)}, keywords = {sys:hidden:inproceedings}, month = 7, title = {Not all Web Pages are Born the Same. Content Tailored Learning for Web QoE Inference}, year = 2022 }

%0 Conference Paper %1 info3-inproceedings-2022-10 %A Casas, Pedro %A Wassermann, Sarah %A Wehner, Nikolas %A Seufert, Michael %A Hoßfeld, Tobias %B IEEE International Symposium on Measurements & Networking (M&N 2022) %D 2022 %T Not all Web Pages are Born the Same. Content Tailored Learning for Web QoE Inference %X Web Quality of Experience (QoE) monitoring is a critical task for Internet Service Providers (ISPs), especially due to the key role played by customer experience in churn management. Previously, we have tackled the problem of Web QoE inference from the ISP perspective, relying on passive measurement of encrypted network traffic and machine learning models. In this paper, we exploit the broad heterogeneity of contents embedded in web pages to improve the state of the art performance in Web QoE inference, relying on web-content learning model tailoring. By analyzing the top-500 most popular web pages of the Internet through unsupervised learning, we discover different web page content classes which realize significantly different Web QoE inference performance. We train supervised learning inference models separately for each of these classes, using the well-known Speed Index (SI) metric as proxy to Web QoE. Empirical evaluations on a large corpus of Web QoE measurements for top popular websites demonstrate that our combined content-tailored approach improves the inference performance of the SI by almost 30% with respect to previous single-model approaches, reducing the QoE inference error in terms of mean opinion scores by more than 40%.
LoRaWAN Network Planning in Smart Environments: Towards Reliability, Scalability, and Cost Reduction Loh, Frank; Geißler, Stefan; Hoßfeld, Tobias in WueWoWAS 22 - KuVS Fachgespräch - Würzburg Workshop on Next-Generation Communication Networks (2022).
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The goal in this work is to present a guidance for LoRaWAN planning to improve overall reliability for message transmissions and scalability. At the end, the cost component is discussed. Therefore, a five step approach is presented that helps to plan a LoRaWAN deployment step by step: Based on the device locations, an initial gateway placement is suggested followed by in-depth frequency and channel access planning. After an initial planning phase, updates for channel access and the initial gateway planning is suggested that should also be done periodically during network operation. Since current gateway placement approaches are only studied with random channel access, there is a lot of potential in the cell planning phase. Furthermore, the performance of different channel access approaches is highly related on network load, and thus cell size and sensor density. Last, the influence of different cell planning ideas on expected costs are discussed.

@inproceedings{info3-inproceedings-2022-20, abstract = {The goal in this work is to present a guidance for LoRaWAN planning to improve overall reliability for message transmissions and scalability. At the end, the cost component is discussed. Therefore, a five step approach is presented that helps to plan a LoRaWAN deployment step by step: Based on the device locations, an initial gateway placement is suggested followed by in-depth frequency and channel access planning. After an initial planning phase, updates for channel access and the initial gateway planning is suggested that should also be done periodically during network operation. Since current gateway placement approaches are only studied with random channel access, there is a lot of potential in the cell planning phase. Furthermore, the performance of different channel access approaches is highly related on network load, and thus cell size and sensor density. Last, the influence of different cell planning ideas on expected costs are discussed.}, author = {Loh, Frank and Geißler, Stefan and Hoßfeld, Tobias}, booktitle = {WueWoWAS 22 - KuVS Fachgespräch - Würzburg Workshop on Next-Generation Communication Networks}, keywords = {5mart}, month = 7, title = {LoRaWAN Network Planning in Smart Environments: Towards Reliability, Scalability, and Cost Reduction}, year = 2022 }

%0 Conference Paper %1 info3-inproceedings-2022-20 %A Loh, Frank %A Geißler, Stefan %A Hoßfeld, Tobias %B WueWoWAS 22 - KuVS Fachgespräch - Würzburg Workshop on Next-Generation Communication Networks %D 2022 %T LoRaWAN Network Planning in Smart Environments: Towards Reliability, Scalability, and Cost Reduction %X The goal in this work is to present a guidance for LoRaWAN planning to improve overall reliability for message transmissions and scalability. At the end, the cost component is discussed. Therefore, a five step approach is presented that helps to plan a LoRaWAN deployment step by step: Based on the device locations, an initial gateway placement is suggested followed by in-depth frequency and channel access planning. After an initial planning phase, updates for channel access and the initial gateway planning is suggested that should also be done periodically during network operation. Since current gateway placement approaches are only studied with random channel access, there is a lot of potential in the cell planning phase. Furthermore, the performance of different channel access approaches is highly related on network load, and thus cell size and sensor density. Last, the influence of different cell planning ideas on expected costs are discussed.
On Learning Hierarchical Embeddings from Encrypted Network Traffic Wehner, Nikolas; Ring, Markus; Schüler, Joshua; Hotho, Andreas; Hoßfeld, Tobias; Seufert, Michael in 33th IEEE/IFIP Network Operations and Management Symposium (NOMS) (2022).
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This work presents a novel concept for learning embeddings from encrypted network traffic. In contrast to existing approaches, we evaluate the feasibility of hierarchical embeddings by iteratively aggregating packet embeddings to flow embeddings, and flow embeddings to trace embeddings. The hierarchical embedding concept was designed to especially consider complex dependencies of Internet traffic on different time scales. We describe this novel embedding concept for the domain of network traffic in full detail, and evaluate its performance for the downstream task of website fingerprinting, i.e., identifying websites from encrypted traffic, which is relevant for network management, e.g., as a prerequisite for QoE monitoring or for intrusion detection. Our evaluation reveals that embeddings are a promising solution for website fingerprinting as our model correctly labels up to 99.8\% of traces from 500 target websites.

@inproceedings{info3-inproceedings-2022-1, abstract = {This work presents a novel concept for learning embeddings from encrypted network traffic. In contrast to existing approaches, we evaluate the feasibility of hierarchical embeddings by iteratively aggregating packet embeddings to flow embeddings, and flow embeddings to trace embeddings. The hierarchical embedding concept was designed to especially consider complex dependencies of Internet traffic on different time scales. We describe this novel embedding concept for the domain of network traffic in full detail, and evaluate its performance for the downstream task of website fingerprinting, i.e., identifying websites from encrypted traffic, which is relevant for network management, e.g., as a prerequisite for QoE monitoring or for intrusion detection. Our evaluation reveals that embeddings are a promising solution for website fingerprinting as our model correctly labels up to 99.8\% of traces from 500 target websites.}, address = {Budapest, Hungary}, author = {Wehner, Nikolas and Ring, Markus and Schüler, Joshua and Hotho, Andreas and Hoßfeld, Tobias and Seufert, Michael}, booktitle = {33th IEEE/IFIP Network Operations and Management Symposium (NOMS)}, keywords = {sys:hidden:inproceedings}, month = 4, title = {On Learning Hierarchical Embeddings from Encrypted Network Traffic}, year = 2022 }

%0 Conference Paper %1 info3-inproceedings-2022-1 %A Wehner, Nikolas %A Ring, Markus %A Schüler, Joshua %A Hotho, Andreas %A Hoßfeld, Tobias %A Seufert, Michael %B 33th IEEE/IFIP Network Operations and Management Symposium (NOMS) %C Budapest, Hungary %D 2022 %T On Learning Hierarchical Embeddings from Encrypted Network Traffic %X This work presents a novel concept for learning embeddings from encrypted network traffic. In contrast to existing approaches, we evaluate the feasibility of hierarchical embeddings by iteratively aggregating packet embeddings to flow embeddings, and flow embeddings to trace embeddings. The hierarchical embedding concept was designed to especially consider complex dependencies of Internet traffic on different time scales. We describe this novel embedding concept for the domain of network traffic in full detail, and evaluate its performance for the downstream task of website fingerprinting, i.e., identifying websites from encrypted traffic, which is relevant for network management, e.g., as a prerequisite for QoE monitoring or for intrusion detection. Our evaluation reveals that embeddings are a promising solution for website fingerprinting as our model correctly labels up to 99.8\% of traces from 500 target websites.
ML-based Performance Prediction of SDN using Simulated Data from Real and Synthetic Networks Dietz, Katharina; Gray, Nicholas; Seufert, Michael; Hoßfeld, Tobias in 33th IEEE/IFIP Network Operations and Management Symposium (NOMS) (2022).
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@inproceedings{info3-inproceedings-2022-2, address = {Budapest, Hungary}, author = {Dietz, Katharina and Gray, Nicholas and Seufert, Michael and Hoßfeld, Tobias}, booktitle = {33th IEEE/IFIP Network Operations and Management Symposium (NOMS)}, keywords = {ucn}, month = 4, title = {ML-based Performance Prediction of SDN using Simulated Data from Real and Synthetic Networks}, year = 2022 }

%0 Conference Paper %1 info3-inproceedings-2022-2 %A Dietz, Katharina %A Gray, Nicholas %A Seufert, Michael %A Hoßfeld, Tobias %B 33th IEEE/IFIP Network Operations and Management Symposium (NOMS) %C Budapest, Hungary %D 2022 %T ML-based Performance Prediction of SDN using Simulated Data from Real and Synthetic Networks
Analytical Model for the Energy Efficiency in Low Power IoT Deployments Hoßfeld, Tobias; Raffeck, Simon; Loh, Frank; Geißler, Stefan in 1st International Workshop on Network Energy Efficiency in the Softwarization Era (2022).
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The recent rise of the Internet of Things (IoT) has given way to numerous challenges and research questions. One of the most critical issues in the area of low powered devices is the question of energy efficiency. Here, technologies like LoRa or Zigbee emerged, promising low power consumption while maintaining adequate performance. However, even when using these tailor made technologies, several configuration aspects need to be taken into account to provide high performance, energy efficient operation. To this end, we propose a generic model to compute the energy efficiency of wireless sensors under the assumption of perfect CSMA/CA channel access. We present numerical results for a typical LoRa device and highlight extensions towards other channel access mechanisms. Finally, we apply Kleinrock's power metric to obtain ideal system configurations for varying load parameters.

@inproceedings{info3-inproceedings-2022-6, abstract = {The recent rise of the Internet of Things (IoT) has given way to numerous challenges and research questions. One of the most critical issues in the area of low powered devices is the question of energy efficiency. Here, technologies like LoRa or Zigbee emerged, promising low power consumption while maintaining adequate performance. However, even when using these tailor made technologies, several configuration aspects need to be taken into account to provide high performance, energy efficient operation. To this end, we propose a generic model to compute the energy efficiency of wireless sensors under the assumption of perfect CSMA/CA channel access. We present numerical results for a typical LoRa device and highlight extensions towards other channel access mechanisms. Finally, we apply Kleinrock's power metric to obtain ideal system configurations for varying load parameters.}, author = {Hoßfeld, Tobias and Raffeck, Simon and Loh, Frank and Geißler, Stefan}, booktitle = {1st International Workshop on Network Energy Efficiency in the Softwarization Era}, keywords = {can}, month = 6, title = {Analytical Model for the Energy Efficiency in Low Power IoT Deployments}, year = 2022 }

%0 Conference Paper %1 info3-inproceedings-2022-6 %A Hoßfeld, Tobias %A Raffeck, Simon %A Loh, Frank %A Geißler, Stefan %B 1st International Workshop on Network Energy Efficiency in the Softwarization Era %D 2022 %T Analytical Model for the Energy Efficiency in Low Power IoT Deployments %X The recent rise of the Internet of Things (IoT) has given way to numerous challenges and research questions. One of the most critical issues in the area of low powered devices is the question of energy efficiency. Here, technologies like LoRa or Zigbee emerged, promising low power consumption while maintaining adequate performance. However, even when using these tailor made technologies, several configuration aspects need to be taken into account to provide high performance, energy efficient operation. To this end, we propose a generic model to compute the energy efficiency of wireless sensors under the assumption of perfect CSMA/CA channel access. We present numerical results for a typical LoRa device and highlight extensions towards other channel access mechanisms. Finally, we apply Kleinrock's power metric to obtain ideal system configurations for varying load parameters.
Data Usage in IoT: A Characterization of GTP Tunnels in M2M Mobile Networks Raffeck, Simon; Geißler, Stefan; Krolikowski, Michael; Gebert, Steffen; Hoßfeld, Tobias in 2nd IFIP/IEEE International workshop on Fully-Flexible Internet Architectures and Protocols for the Next-Generation Tactile Internet (FlexNGIA) (2022).
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IoT and M2M devices have seen a significant growth in usage and deployment over the last years. Gaining insight into device and data usage behavior exhibited by the participants of mobile networks is elementary for MNO and MVNO to scale their networks and provide a reliable service. This work aims to make use of its first of a kind dataset, spanning multiple countries and MNO, to provide a detailed characterization of GTP tunnels and devices. To this end, general statistics are used to describe the observed data traffic focusing on the distribution of the tunnel duration and volume as well as periodic device behavior. An approximate metric is introduced to analyze the periodicity and synchronicity of IoT devices. Lastly, we publish the data investigated in this work and provide a large scale dataset on the data usage behavior of IoT devices to interested researchers.

@inproceedings{info3-inproceedings-2022-5, abstract = {IoT and M2M devices have seen a significant growth in usage and deployment over the last years. Gaining insight into device and data usage behavior exhibited by the participants of mobile networks is elementary for MNO and MVNO to scale their networks and provide a reliable service. This work aims to make use of its first of a kind dataset, spanning multiple countries and MNO, to provide a detailed characterization of GTP tunnels and devices. To this end, general statistics are used to describe the observed data traffic focusing on the distribution of the tunnel duration and volume as well as periodic device behavior. An approximate metric is introduced to analyze the periodicity and synchronicity of IoT devices. Lastly, we publish the data investigated in this work and provide a large scale dataset on the data usage behavior of IoT devices to interested researchers.}, author = {Raffeck, Simon and Geißler, Stefan and Krolikowski, Michael and Gebert, Steffen and Hoßfeld, Tobias}, booktitle = {2nd IFIP/IEEE International workshop on Fully-Flexible Internet Architectures and Protocols for the Next-Generation Tactile Internet (FlexNGIA)}, keywords = {can}, month = 4, title = {Data Usage in IoT: A Characterization of GTP Tunnels in M2M Mobile Networks}, year = 2022 }

%0 Conference Paper %1 info3-inproceedings-2022-5 %A Raffeck, Simon %A Geißler, Stefan %A Krolikowski, Michael %A Gebert, Steffen %A Hoßfeld, Tobias %B 2nd IFIP/IEEE International workshop on Fully-Flexible Internet Architectures and Protocols for the Next-Generation Tactile Internet (FlexNGIA) %D 2022 %T Data Usage in IoT: A Characterization of GTP Tunnels in M2M Mobile Networks %X IoT and M2M devices have seen a significant growth in usage and deployment over the last years. Gaining insight into device and data usage behavior exhibited by the participants of mobile networks is elementary for MNO and MVNO to scale their networks and provide a reliable service. This work aims to make use of its first of a kind dataset, spanning multiple countries and MNO, to provide a detailed characterization of GTP tunnels and devices. To this end, general statistics are used to describe the observed data traffic focusing on the distribution of the tunnel duration and volume as well as periodic device behavior. An approximate metric is introduced to analyze the periodicity and synchronicity of IoT devices. Lastly, we publish the data investigated in this work and provide a large scale dataset on the data usage behavior of IoT devices to interested researchers.
DBM: Decentralized Burst Mitigation for Self-Organizing LoRa Deployments Raffeck, Simon; Geißler, Stefan; Hoßfeld, Tobias in KuVS Fachgespräch - Würzburg Workshop on Modeling, Analysis and Simulation of Next-Generation Communication Networks 2022 (2022).
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@inproceedings{info3-inproceedings-2022-7, author = {Raffeck, Simon and Geißler, Stefan and Hoßfeld, Tobias}, booktitle = {KuVS Fachgespräch - Würzburg Workshop on Modeling, Analysis and Simulation of Next-Generation Communication Networks 2022}, keywords = {can}, month = 7, title = {DBM: Decentralized Burst Mitigation for Self-Organizing LoRa Deployments}, year = 2022 }

%0 Conference Paper %1 info3-inproceedings-2022-7 %A Raffeck, Simon %A Geißler, Stefan %A Hoßfeld, Tobias %B KuVS Fachgespräch - Würzburg Workshop on Modeling, Analysis and Simulation of Next-Generation Communication Networks 2022 %D 2022 %T DBM: Decentralized Burst Mitigation for Self-Organizing LoRa Deployments
Graph-Based Gateway Placement for Better Performance in LoRaWAN Deployments Loh, Frank; Mehling, Noah; Geißler, Stefan; Hoßfeld, Tobias in 20th Mediterranean Communication and Computer Networking Conference (MedComNet) (2022).
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Low Power Wide Area Networks with Long Range Wide Area Networks (LoRaWANs) as one of their most prominent representatives are very promising solutions for future Internet of Things deployments. The technology is characterized by low energy requirements leading to long battery lifetimes. However, the drawback is very limited throughput rates. However, the unreliable nature of the LoRa technology is hindering the adoption. Especially its random channel access approach leads to significant message collisions and thus, data loss in larger deployments. From a network planning point of view, one possibility to deal with collisions is the reduction of potentially colliding messages at the frequency bands in combination with limiting the transmission duration of messages. For that reason, we present a novel graph-based gateway placement approach. The main focus is collision probability reduction, which directly increases reliability in LoRaWAN deployments. We show that our approach performs similar to state-of-the-art related work in the worst case and reduces the required number of gateways by up to 40% while reducing the collision probability by up to 70%. Furthermore, we discuss the scalability of our approach to cover arbitrarily large networks with gateways and only little overhead by splitting the problem into smaller sub-problems.

@inproceedings{info3-inproceedings-2022-19, abstract = {Low Power Wide Area Networks with Long Range Wide Area Networks (LoRaWANs) as one of their most prominent representatives are very promising solutions for future Internet of Things deployments. The technology is characterized by low energy requirements leading to long battery lifetimes. However, the drawback is very limited throughput rates. However, the unreliable nature of the LoRa technology is hindering the adoption. Especially its random channel access approach leads to significant message collisions and thus, data loss in larger deployments. From a network planning point of view, one possibility to deal with collisions is the reduction of potentially colliding messages at the frequency bands in combination with limiting the transmission duration of messages. For that reason, we present a novel graph-based gateway placement approach. The main focus is collision probability reduction, which directly increases reliability in LoRaWAN deployments. We show that our approach performs similar to state-of-the-art related work in the worst case and reduces the required number of gateways by up to 40% while reducing the collision probability by up to 70%. Furthermore, we discuss the scalability of our approach to cover arbitrarily large networks with gateways and only little overhead by splitting the problem into smaller sub-problems.}, author = {Loh, Frank and Mehling, Noah and Geißler, Stefan and Hoßfeld, Tobias}, booktitle = {20th Mediterranean Communication and Computer Networking Conference (MedComNet)}, keywords = {5mart}, month = 6, title = {Graph-Based Gateway Placement for Better Performance in LoRaWAN Deployments}, year = 2022 }

%0 Conference Paper %1 info3-inproceedings-2022-19 %A Loh, Frank %A Mehling, Noah %A Geißler, Stefan %A Hoßfeld, Tobias %B 20th Mediterranean Communication and Computer Networking Conference (MedComNet) %D 2022 %T Graph-Based Gateway Placement for Better Performance in LoRaWAN Deployments %X Low Power Wide Area Networks with Long Range Wide Area Networks (LoRaWANs) as one of their most prominent representatives are very promising solutions for future Internet of Things deployments. The technology is characterized by low energy requirements leading to long battery lifetimes. However, the drawback is very limited throughput rates. However, the unreliable nature of the LoRa technology is hindering the adoption. Especially its random channel access approach leads to significant message collisions and thus, data loss in larger deployments. From a network planning point of view, one possibility to deal with collisions is the reduction of potentially colliding messages at the frequency bands in combination with limiting the transmission duration of messages. For that reason, we present a novel graph-based gateway placement approach. The main focus is collision probability reduction, which directly increases reliability in LoRaWAN deployments. We show that our approach performs similar to state-of-the-art related work in the worst case and reduces the required number of gateways by up to 40% while reducing the collision probability by up to 70%. Furthermore, we discuss the scalability of our approach to cover arbitrarily large networks with gateways and only little overhead by splitting the problem into smaller sub-problems.
Identification of Signaling Patterns in Mobile IoT Signaling Traffic Vomhoff, Viktoria; Geißler, Stefan; Hoßfeld, Tobias in WueWoWAS 22 - KuVS Fachgespräch - Würzburg Workshop on Next-Generation Communication Networks (2022).
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@inproceedings{info3-inproceedings-2022-8, author = {Vomhoff, Viktoria and Geißler, Stefan and Hoßfeld, Tobias}, booktitle = {WueWoWAS 22 - KuVS Fachgespräch - Würzburg Workshop on Next-Generation Communication Networks}, keywords = {can}, month = 7, title = {Identification of Signaling Patterns in Mobile IoT Signaling Traffic}, year = 2022 }

%0 Conference Paper %1 info3-inproceedings-2022-8 %A Vomhoff, Viktoria %A Geißler, Stefan %A Hoßfeld, Tobias %B WueWoWAS 22 - KuVS Fachgespräch - Würzburg Workshop on Next-Generation Communication Networks %D 2022 %T Identification of Signaling Patterns in Mobile IoT Signaling Traffic
A Vital Improvement? Relating Google’s Core Web Vitals to Actual Web QoE Wehner, Nikolas; Amir, Monisha; Seufert, Michael; Schatz, Raimund; Hoßfeld, Tobias in 14th International Conference on Quality of Multimedia Experience (QoMEX), Best Paper Award (2022).
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Providing sophisticated Web Quality of Experience (QoE) has become paramount for web service providers and network operators alike. Due to advances in Web technologies (HTML5, responsive design, etc.), traditional Web QoE models focusing mainly on loading times have to be refined and improved. In this work, we relate Google's Core Web Vitals, a set of metrics for improving user experience, to the loading time aspects of Web QoE. To this end, we first perform objective measurements in the Web using Google's Lighthouse. To close the gap between metrics and experience, we complement these objective measurements with subjective assessment by performing multiple crowdsourcing QoE studies. In these studies, we use CWeQS, a customized framework to emulate the entire web page loading process, and ask users for their experience while controlling the Core Web Vitals. Our results suggest that the Core Web Vitals have less predictive value for Web QoE than expected and that page loading times remain the main influence factor in this context.

@inproceedings{info3-inproceedings-2022-12, abstract = {Providing sophisticated Web Quality of Experience (QoE) has become paramount for web service providers and network operators alike. Due to advances in Web technologies (HTML5, responsive design, etc.), traditional Web QoE models focusing mainly on loading times have to be refined and improved. In this work, we relate Google's Core Web Vitals, a set of metrics for improving user experience, to the loading time aspects of Web QoE. To this end, we first perform objective measurements in the Web using Google's Lighthouse. To close the gap between metrics and experience, we complement these objective measurements with subjective assessment by performing multiple crowdsourcing QoE studies. In these studies, we use CWeQS, a customized framework to emulate the entire web page loading process, and ask users for their experience while controlling the Core Web Vitals. Our results suggest that the Core Web Vitals have less predictive value for Web QoE than expected and that page loading times remain the main influence factor in this context.}, address = {Lippstadt, Germany}, author = {Wehner, Nikolas and Amir, Monisha and Seufert, Michael and Schatz, Raimund and Hoßfeld, Tobias}, booktitle = {14th International Conference on Quality of Multimedia Experience (QoMEX), Best Paper Award}, keywords = {ucn}, month = 9, title = {A Vital Improvement? Relating Google's Core Web Vitals to Actual Web QoE}, year = 2022 }

%0 Conference Paper %1 info3-inproceedings-2022-12 %A Wehner, Nikolas %A Amir, Monisha %A Seufert, Michael %A Schatz, Raimund %A Hoßfeld, Tobias %B 14th International Conference on Quality of Multimedia Experience (QoMEX), Best Paper Award %C Lippstadt, Germany %D 2022 %T A Vital Improvement? Relating Google's Core Web Vitals to Actual Web QoE %X Providing sophisticated Web Quality of Experience (QoE) has become paramount for web service providers and network operators alike. Due to advances in Web technologies (HTML5, responsive design, etc.), traditional Web QoE models focusing mainly on loading times have to be refined and improved. In this work, we relate Google's Core Web Vitals, a set of metrics for improving user experience, to the loading time aspects of Web QoE. To this end, we first perform objective measurements in the Web using Google's Lighthouse. To close the gap between metrics and experience, we complement these objective measurements with subjective assessment by performing multiple crowdsourcing QoE studies. In these studies, we use CWeQS, a customized framework to emulate the entire web page loading process, and ask users for their experience while controlling the Core Web Vitals. Our results suggest that the Core Web Vitals have less predictive value for Web QoE than expected and that page loading times remain the main influence factor in this context.
Waiting along the Path: How Browsing Delays Impact the QoE of Music Streaming Applications Seufert, Anika; Schweifler, Ralf; Poignée, Fabian; Seufert, Michael; Hoßfeld, Tobias in 14th International Conference on Quality of Multimedia Experience (QoMEX) (2022).
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Streaming has become the dominant source of media consumption, which not only applies to the widely researched field of video streaming, but also to music streaming. Here, previous studies so far have only researched the impact of streaming aspects, such as stalling events or initial loading times, on the QoE of music streaming. However, when using a music streaming application, users are already facing waiting times along the click path before they can start the actual streaming. These waiting times are caused by browsing delays, e.g., during searching for songs or scrolling through playlists, and can potentially deteriorate the QoE of the music streaming application. In this work, we conduct an online QoE study to quantify the impact of these browsing delays with the support of an emulated mobile music streaming web app. We found that browsing delays have no impact on the music streaming QoE, which shows that users are able to clearly distinguish between the two main functionalities of such apps, namely, browsing and streaming. However, browsing delays significantly reduce the QoE of the entire music streaming application, to a similar extent as if QoE degradations happen during the actual streaming. This shows that both browsing and streaming are equally important and have to be considered when designing music streaming applications.

@inproceedings{info3-inproceedings-2022-13, abstract = {Streaming has become the dominant source of media consumption, which not only applies to the widely researched field of video streaming, but also to music streaming. Here, previous studies so far have only researched the impact of streaming aspects, such as stalling events or initial loading times, on the QoE of music streaming. However, when using a music streaming application, users are already facing waiting times along the click path before they can start the actual streaming. These waiting times are caused by browsing delays, e.g., during searching for songs or scrolling through playlists, and can potentially deteriorate the QoE of the music streaming application. In this work, we conduct an online QoE study to quantify the impact of these browsing delays with the support of an emulated mobile music streaming web app. We found that browsing delays have no impact on the music streaming QoE, which shows that users are able to clearly distinguish between the two main functionalities of such apps, namely, browsing and streaming. However, browsing delays significantly reduce the QoE of the entire music streaming application, to a similar extent as if QoE degradations happen during the actual streaming. This shows that both browsing and streaming are equally important and have to be considered when designing music streaming applications.}, author = {Seufert, Anika and Schweifler, Ralf and Poignée, Fabian and Seufert, Michael and Hoßfeld, Tobias}, booktitle = {14th International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {sys:hidden:inproceedings}, month = 9, title = {Waiting along the Path: How Browsing Delays Impact the QoE of Music Streaming Applications}, year = 2022 }

%0 Conference Paper %1 info3-inproceedings-2022-13 %A Seufert, Anika %A Schweifler, Ralf %A Poignée, Fabian %A Seufert, Michael %A Hoßfeld, Tobias %B 14th International Conference on Quality of Multimedia Experience (QoMEX) %D 2022 %T Waiting along the Path: How Browsing Delays Impact the QoE of Music Streaming Applications %X Streaming has become the dominant source of media consumption, which not only applies to the widely researched field of video streaming, but also to music streaming. Here, previous studies so far have only researched the impact of streaming aspects, such as stalling events or initial loading times, on the QoE of music streaming. However, when using a music streaming application, users are already facing waiting times along the click path before they can start the actual streaming. These waiting times are caused by browsing delays, e.g., during searching for songs or scrolling through playlists, and can potentially deteriorate the QoE of the music streaming application. In this work, we conduct an online QoE study to quantify the impact of these browsing delays with the support of an emulated mobile music streaming web app. We found that browsing delays have no impact on the music streaming QoE, which shows that users are able to clearly distinguish between the two main functionalities of such apps, namely, browsing and streaming. However, browsing delays significantly reduce the QoE of the entire music streaming application, to a similar extent as if QoE degradations happen during the actual streaming. This shows that both browsing and streaming are equally important and have to be considered when designing music streaming applications.
Affordable Measurement Setups for Networking Device Latency with Sub-Microsecond Accuracy Grigorjew, Alexej; Diederich, Philip; Hoßfeld, Tobias; Kellerer, Wolfgang in WueWoWAS’22 KuVS Fachgespraech - Wuerzburg Workshop on Next-Generation Communication Networks (2022).
- [ Abstract ]
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This document presents a networking latency measurement setup that focuses on affordability and universal applicability, and can provide sub-microsecond accuracy. It explains the prerequisites, hardware choices, and considerations to respect during measurement. In addition, it discusses the necessity for exhaustive latency measurements when dealing with high availability and low latency requirements. Preliminary results show that the accuracy is within 0.02 microseconds when used with the Intel I350-T2 network adapter.

@inproceedings{info3-inproceedings-2022-14, abstract = {This document presents a networking latency measurement setup that focuses on affordability and universal applicability, and can provide sub-microsecond accuracy. It explains the prerequisites, hardware choices, and considerations to respect during measurement. In addition, it discusses the necessity for exhaustive latency measurements when dealing with high availability and low latency requirements. Preliminary results show that the accuracy is within 0.02 microseconds when used with the Intel I350-T2 network adapter.}, author = {Grigorjew, Alexej and Diederich, Philip and Hoßfeld, Tobias and Kellerer, Wolfgang}, booktitle = {WueWoWAS'22 KuVS Fachgespraech - Wuerzburg Workshop on Next-Generation Communication Networks}, keywords = {appaware2}, month = 7, title = {Affordable Measurement Setups for Networking Device Latency with Sub-Microsecond Accuracy}, year = 2022 }

%0 Conference Paper %1 info3-inproceedings-2022-14 %A Grigorjew, Alexej %A Diederich, Philip %A Hoßfeld, Tobias %A Kellerer, Wolfgang %B WueWoWAS'22 KuVS Fachgespraech - Wuerzburg Workshop on Next-Generation Communication Networks %D 2022 %T Affordable Measurement Setups for Networking Device Latency with Sub-Microsecond Accuracy %X This document presents a networking latency measurement setup that focuses on affordability and universal applicability, and can provide sub-microsecond accuracy. It explains the prerequisites, hardware choices, and considerations to respect during measurement. In addition, it discusses the necessity for exhaustive latency measurements when dealing with high availability and low latency requirements. Preliminary results show that the accuracy is within 0.02 microseconds when used with the Intel I350-T2 network adapter.
Constant Delay Switching: Asynchronous Traffic Shaping with Jitter Control Grigorjew, Alexej; Metzger, Florian; Hoßfeld, Tobias; Specht, Johannes; Götz, Franz-Josef; Chen, Feng; Schmitt, Jürgen in 2022 IFIP Networking Conference (IFIP Networking) (2022).
- [ Abstract ]
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Recent developments in the Time Sensitive Networking (TSN) group have put forth a number of mechanisms to improve deterministic latency in layer 2 switches. Their shaping approaches differ with respect to prerequisites, flexibility, maximum latency, and latency variation (jitter). Asynchronous solutions provide flexibility in dynamic scenarios, but Credit-Based Shaping (CBS) and Asynchronous Traffic Shaping (ATS) come with a high latency variance, as the minimum latency is not affected by them. Some applications in industrial and automotive use cases require low jitter while trying to avoid a dependency on time synchronization, and even TSN's redundancy mechanism benefits from a lower latency variance. This work is bridging the gap between low-jitter transmission requirements and asynchronous shaping mechanisms. In this paper, the application of a stateless Asynchronous Constant Delay Shaper (ACDS) is discussed. It collects the queuing duration from the previous bridge to delay each frame for the remaining time such that a constant per-hop delay for each frame is achieved. The discussion includes the prerequisites, the mechanism itself, and its technical complexity, as well as a formal analysis of its guaranteed latency by proving its relation to a token-bucket based ATS. Further, two extensions are discussed, and an evaluation shows the applicability of ACDS by comparing its jitter to ATS in a frame-level simulation.

@inproceedings{info3-inproceedings-2022-15, abstract = {Recent developments in the Time Sensitive Networking (TSN) group have put forth a number of mechanisms to improve deterministic latency in layer 2 switches. Their shaping approaches differ with respect to prerequisites, flexibility, maximum latency, and latency variation (jitter). Asynchronous solutions provide flexibility in dynamic scenarios, but Credit-Based Shaping (CBS) and Asynchronous Traffic Shaping (ATS) come with a high latency variance, as the minimum latency is not affected by them. Some applications in industrial and automotive use cases require low jitter while trying to avoid a dependency on time synchronization, and even TSN's redundancy mechanism benefits from a lower latency variance. This work is bridging the gap between low-jitter transmission requirements and asynchronous shaping mechanisms. In this paper, the application of a stateless Asynchronous Constant Delay Shaper (ACDS) is discussed. It collects the queuing duration from the previous bridge to delay each frame for the remaining time such that a constant per-hop delay for each frame is achieved. The discussion includes the prerequisites, the mechanism itself, and its technical complexity, as well as a formal analysis of its guaranteed latency by proving its relation to a token-bucket based ATS. Further, two extensions are discussed, and an evaluation shows the applicability of ACDS by comparing its jitter to ATS in a frame-level simulation.}, author = {Grigorjew, Alexej and Metzger, Florian and Hoßfeld, Tobias and Specht, Johannes and Götz, Franz-Josef and Chen, Feng and Schmitt, Jürgen}, booktitle = {2022 IFIP Networking Conference (IFIP Networking)}, keywords = {kosinu5}, month = 6, title = {Constant Delay Switching: Asynchronous Traffic Shaping with Jitter Control}, year = 2022 }

%0 Conference Paper %1 info3-inproceedings-2022-15 %A Grigorjew, Alexej %A Metzger, Florian %A Hoßfeld, Tobias %A Specht, Johannes %A Götz, Franz-Josef %A Chen, Feng %A Schmitt, Jürgen %B 2022 IFIP Networking Conference (IFIP Networking) %D 2022 %T Constant Delay Switching: Asynchronous Traffic Shaping with Jitter Control %X Recent developments in the Time Sensitive Networking (TSN) group have put forth a number of mechanisms to improve deterministic latency in layer 2 switches. Their shaping approaches differ with respect to prerequisites, flexibility, maximum latency, and latency variation (jitter). Asynchronous solutions provide flexibility in dynamic scenarios, but Credit-Based Shaping (CBS) and Asynchronous Traffic Shaping (ATS) come with a high latency variance, as the minimum latency is not affected by them. Some applications in industrial and automotive use cases require low jitter while trying to avoid a dependency on time synchronization, and even TSN's redundancy mechanism benefits from a lower latency variance. This work is bridging the gap between low-jitter transmission requirements and asynchronous shaping mechanisms. In this paper, the application of a stateless Asynchronous Constant Delay Shaper (ACDS) is discussed. It collects the queuing duration from the previous bridge to delay each frame for the remaining time such that a constant per-hop delay for each frame is achieved. The discussion includes the prerequisites, the mechanism itself, and its technical complexity, as well as a formal analysis of its guaranteed latency by proving its relation to a token-bucket based ATS. Further, two extensions are discussed, and an evaluation shows the applicability of ACDS by comparing its jitter to ATS in a frame-level simulation.
Comparing Traditional and GAN-based Approaches for the Synthesis of Wide Area Network Topologies Dietz, Katharina; Seufert, Michael; Hoßfeld, Tobias in 18th International Conference on Network and Service Management (CNSM) (2022).
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@inproceedings{info3-inproceedings-2022-16, address = {Thessaloniki, Greece}, author = {Dietz, Katharina and Seufert, Michael and Hoßfeld, Tobias}, booktitle = {18th International Conference on Network and Service Management (CNSM)}, keywords = {ucn}, month = 10, title = {Comparing Traditional and GAN-based Approaches for the Synthesis of Wide Area Network Topologies}, year = 2022 }

%0 Conference Paper %1 info3-inproceedings-2022-16 %A Dietz, Katharina %A Seufert, Michael %A Hoßfeld, Tobias %B 18th International Conference on Network and Service Management (CNSM) %C Thessaloniki, Greece %D 2022 %T Comparing Traditional and GAN-based Approaches for the Synthesis of Wide Area Network Topologies
Discrete-Time Analysis of Multi-Component Queuing Networks under Renewal Approximation Geißler, Stefan; Lange, Stanislav; Haßllinger, Gerhard; Tran-Gia, Phuoc; Hoßfeld, Tobias in 34st International Teletraffic Congress (ITC). , Shenzhen, China (2022).
- [ Abstract ]
- [ BibTeX ]
- [ EndNote ]
The analytical and numerical performance evaluation of network components and distributed systems has been a staple in the networking community for many years. However, the ever growing complexity of modern systems and the need to gain detailed insights into systems consisting of many, interconnected components emphasizes the need for an extension to the classical single-component approach, and although approaches like Jackson Networks exist, their limited application scope lags behind the complexity of modern environments. To this end, we revisit existing models of the common Gi/Gi/1-oo queue, extend them to allow the concatenation of multiple queueing components, and evaluate the approximation error introduced through renewal approximation. We revisit previously performed parameter studies and evaluate the approximation error for a wide range of parameter combinations that we can solve through the power of modern computing equipment and efficient numerical implementations of our models. We show the main impact factors for the linear concatenation of queueing components as well as the split and superposition of processes. Our evaluations show that the renewal approximation can be applied to a wide range of parameters while still obtaining results within acceptable error margins.

@inproceedings{info3-inproceedings-2022-17, abstract = {The analytical and numerical performance evaluation of network components and distributed systems has been a staple in the networking community for many years. However, the ever growing complexity of modern systems and the need to gain detailed insights into systems consisting of many, interconnected components emphasizes the need for an extension to the classical single-component approach, and although approaches like Jackson Networks exist, their limited application scope lags behind the complexity of modern environments. To this end, we revisit existing models of the common Gi/Gi/1-oo queue, extend them to allow the concatenation of multiple queueing components, and evaluate the approximation error introduced through renewal approximation. We revisit previously performed parameter studies and evaluate the approximation error for a wide range of parameter combinations that we can solve through the power of modern computing equipment and efficient numerical implementations of our models. We show the main impact factors for the linear concatenation of queueing components as well as the split and superposition of processes. Our evaluations show that the renewal approximation can be applied to a wide range of parameters while still obtaining results within acceptable error margins.}, author = {Geißler, Stefan and Lange, Stanislav and Haßllinger, Gerhard and Tran-Gia, Phuoc and Hoßfeld, Tobias}, booktitle = {34st International Teletraffic Congress (ITC). , Shenzhen, China}, keywords = {can}, month = 9, title = {Discrete-Time Analysis of Multi-Component Queuing Networks under Renewal Approximation}, year = 2022 }

%0 Conference Paper %1 info3-inproceedings-2022-17 %A Geißler, Stefan %A Lange, Stanislav %A Haßllinger, Gerhard %A Tran-Gia, Phuoc %A Hoßfeld, Tobias %B 34st International Teletraffic Congress (ITC). , Shenzhen, China %D 2022 %T Discrete-Time Analysis of Multi-Component Queuing Networks under Renewal Approximation %X The analytical and numerical performance evaluation of network components and distributed systems has been a staple in the networking community for many years. However, the ever growing complexity of modern systems and the need to gain detailed insights into systems consisting of many, interconnected components emphasizes the need for an extension to the classical single-component approach, and although approaches like Jackson Networks exist, their limited application scope lags behind the complexity of modern environments. To this end, we revisit existing models of the common Gi/Gi/1-oo queue, extend them to allow the concatenation of multiple queueing components, and evaluate the approximation error introduced through renewal approximation. We revisit previously performed parameter studies and evaluate the approximation error for a wide range of parameter combinations that we can solve through the power of modern computing equipment and efficient numerical implementations of our models. We show the main impact factors for the linear concatenation of queueing components as well as the split and superposition of processes. Our evaluations show that the renewal approximation can be applied to a wide range of parameters while still obtaining results within acceptable error margins.
X-Ray Goggles for the ISP: Improving in-Network Web and App QoE Monitoring with Deep Learning Casas, Pedro; Wassermann, Sarah; Seufert, Michael; Wehner, Nikolas; Dinica, Olivia; Hoßfeld, Tobias in Network Traffic Measurement and Analysis Conference (TMA) (2022).
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The wide adoption of end-to-end encryption is drastically limiting the visibility Internet Service Providers (ISPs) have on the performance of the services consumed by their customers. In times of strong competition, where customer experience plays a key role in churn management, ISPs require novel solutions enabling network-wide Quality of Experience (QoE) monitoring. To this end, we present DeepQoE, a deep-learning based approach to infer the QoE of web services and mobile applications from the ISP perspective, relying exclusively on the analysis of encrypted network traffic. Using raw features derived from the encrypted stream of bytes as input to deep Convolutional Neural Networks (CNNs), DeepQoE infers the Speed Index of web browsing sessions and general mobile apps with unprecedented accuracy, improving the state of the art by more than 25%, and reducing the QoE inference error in terms of mean opinion scores by nearly 40%. DeepQoE implements a web fingerprinting solution to identify individual web browsing sessions within concurrent web pages traffic, enabling highly detailed, per web page QoE inference in practical deployments. Extensive evaluations over a large and heterogeneous dataset composed of web and app measurements, using different device types and for top-popular websites and apps, confirm the out-performance of DeepQoE over previously used shallow-learning models, as well as the deep-model generalization to different devices, web pages, apps, and network setups. DeepQoE is the first deployable system providing such a deep, highly-detailed QoE for individual web browsing and mobile apps over encrypted traffic, using deep learning models on heterogeneous measurements.

@inproceedings{info3-inproceedings-2022-11, abstract = {The wide adoption of end-to-end encryption is drastically limiting the visibility Internet Service Providers (ISPs) have on the performance of the services consumed by their customers. In times of strong competition, where customer experience plays a key role in churn management, ISPs require novel solutions enabling network-wide Quality of Experience (QoE) monitoring. To this end, we present DeepQoE, a deep-learning based approach to infer the QoE of web services and mobile applications from the ISP perspective, relying exclusively on the analysis of encrypted network traffic. Using raw features derived from the encrypted stream of bytes as input to deep Convolutional Neural Networks (CNNs), DeepQoE infers the Speed Index of web browsing sessions and general mobile apps with unprecedented accuracy, improving the state of the art by more than 25%, and reducing the QoE inference error in terms of mean opinion scores by nearly 40%. DeepQoE implements a web fingerprinting solution to identify individual web browsing sessions within concurrent web pages traffic, enabling highly detailed, per web page QoE inference in practical deployments. Extensive evaluations over a large and heterogeneous dataset composed of web and app measurements, using different device types and for top-popular websites and apps, confirm the out-performance of DeepQoE over previously used shallow-learning models, as well as the deep-model generalization to different devices, web pages, apps, and network setups. DeepQoE is the first deployable system providing such a deep, highly-detailed QoE for individual web browsing and mobile apps over encrypted traffic, using deep learning models on heterogeneous measurements.}, author = {Casas, Pedro and Wassermann, Sarah and Seufert, Michael and Wehner, Nikolas and Dinica, Olivia and Hoßfeld, Tobias}, booktitle = {Network Traffic Measurement and Analysis Conference (TMA)}, keywords = {sys:hidden:inproceedings}, month = 6, title = {X-Ray Goggles for the ISP: Improving in-Network Web and App QoE Monitoring with Deep Learning}, year = 2022 }

%0 Conference Paper %1 info3-inproceedings-2022-11 %A Casas, Pedro %A Wassermann, Sarah %A Seufert, Michael %A Wehner, Nikolas %A Dinica, Olivia %A Hoßfeld, Tobias %B Network Traffic Measurement and Analysis Conference (TMA) %D 2022 %T X-Ray Goggles for the ISP: Improving in-Network Web and App QoE Monitoring with Deep Learning %X The wide adoption of end-to-end encryption is drastically limiting the visibility Internet Service Providers (ISPs) have on the performance of the services consumed by their customers. In times of strong competition, where customer experience plays a key role in churn management, ISPs require novel solutions enabling network-wide Quality of Experience (QoE) monitoring. To this end, we present DeepQoE, a deep-learning based approach to infer the QoE of web services and mobile applications from the ISP perspective, relying exclusively on the analysis of encrypted network traffic. Using raw features derived from the encrypted stream of bytes as input to deep Convolutional Neural Networks (CNNs), DeepQoE infers the Speed Index of web browsing sessions and general mobile apps with unprecedented accuracy, improving the state of the art by more than 25%, and reducing the QoE inference error in terms of mean opinion scores by nearly 40%. DeepQoE implements a web fingerprinting solution to identify individual web browsing sessions within concurrent web pages traffic, enabling highly detailed, per web page QoE inference in practical deployments. Extensive evaluations over a large and heterogeneous dataset composed of web and app measurements, using different device types and for top-popular websites and apps, confirm the out-performance of DeepQoE over previously used shallow-learning models, as well as the deep-model generalization to different devices, web pages, apps, and network setups. DeepQoE is the first deployable system providing such a deep, highly-detailed QoE for individual web browsing and mobile apps over encrypted traffic, using deep learning models on heterogeneous measurements.
Generic Model to Quantify Energy Consumption for Different LoRaWAN Channel Access Methods Loh, Frank; Raffeck, Simon; Geißler, Stefan; Hoßfeld, Tobias in 18th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob) (2022).
- [ Abstract ]
- [ BibTeX ]
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- [ Download ]
LoRaWAN is one of the most promising Internet of Things technologies with regard to low energy consumption. However, the currently used random channel access has much potential for improvement. Thus, current literature studies alternative channel access approaches, but the energy consumption is often not taken into consideration. For that reason, we present a generic model to quantify energy consumption in LoRaWAN for different channel access mechanisms based on a state machine. With our model, we can describe the energy consumption for specific access mechanisms or for the complete network. Our model shows that random access only performs best if no additional receive windows are opened. A simple improvement is Listen before Talk. For networks with high load, improvements are achieved by a more complex scheduled MAC. Our model serves as a basis for future energy consumption studies, conducted through measurements or simulations.

@inproceedings{info3-inproceedings-2022-21, abstract = {LoRaWAN is one of the most promising Internet of Things technologies with regard to low energy consumption. However, the currently used random channel access has much potential for improvement. Thus, current literature studies alternative channel access approaches, but the energy consumption is often not taken into consideration. For that reason, we present a generic model to quantify energy consumption in LoRaWAN for different channel access mechanisms based on a state machine. With our model, we can describe the energy consumption for specific access mechanisms or for the complete network. Our model shows that random access only performs best if no additional receive windows are opened. A simple improvement is Listen before Talk. For networks with high load, improvements are achieved by a more complex scheduled MAC. Our model serves as a basis for future energy consumption studies, conducted through measurements or simulations.}, author = {Loh, Frank and Raffeck, Simon and Geißler, Stefan and Hoßfeld, Tobias}, booktitle = {18th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob)}, keywords = {5mart}, month = 10, title = {Generic Model to Quantify Energy Consumption for Different LoRaWAN Channel Access Methods}, year = 2022 }

%0 Conference Paper %1 info3-inproceedings-2022-21 %A Loh, Frank %A Raffeck, Simon %A Geißler, Stefan %A Hoßfeld, Tobias %B 18th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob) %D 2022 %T Generic Model to Quantify Energy Consumption for Different LoRaWAN Channel Access Methods %X LoRaWAN is one of the most promising Internet of Things technologies with regard to low energy consumption. However, the currently used random channel access has much potential for improvement. Thus, current literature studies alternative channel access approaches, but the energy consumption is often not taken into consideration. For that reason, we present a generic model to quantify energy consumption in LoRaWAN for different channel access mechanisms based on a state machine. With our model, we can describe the energy consumption for specific access mechanisms or for the complete network. Our model shows that random access only performs best if no additional receive windows are opened. A simple improvement is Listen before Talk. For networks with high load, improvements are achieved by a more complex scheduled MAC. Our model serves as a basis for future energy consumption studies, conducted through measurements or simulations.
On Inter-Rater Reliability for Crowdsourced QoE Hoßfeld, Tobias; Seufert, Michael; Naderi, Babak in 13th International Conference on Quality of Multimedia Experience (QoMEX) (2021).
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@inproceedings{info3-inproceedings-2021-9, address = {Montreal, Canada (Virtual Conference)}, author = {Hoßfeld, Tobias and Seufert, Michael and Naderi, Babak}, booktitle = {13th International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {ucn}, month = 6, title = {On Inter-Rater Reliability for Crowdsourced QoE}, year = 2021 }

%0 Conference Paper %1 info3-inproceedings-2021-9 %A Hoßfeld, Tobias %A Seufert, Michael %A Naderi, Babak %B 13th International Conference on Quality of Multimedia Experience (QoMEX) %C Montreal, Canada (Virtual Conference) %D 2021 %T On Inter-Rater Reliability for Crowdsourced QoE
Robust Gateway Placement for Scalable LoRaWAN Loh, Frank; Bau, Dominique; Zink, Johannes; Wolff, Alexander; Hoßfeld, Tobias in 13th IFIP Wireless and Mobile Networking Conference (WMNC) (2021).
- [ Abstract ]
- [ BibTeX ]
- [ EndNote ]
- [ Download ]
Many exciting applications are currently emerging due to the use of technology from the Internet of Things (IoT) in Smart Cities. In recent years, Long Range Wide Area Networks (LoRaWANs) have become one of the main technologies in this field due to long distance coverage, low power consumption sensors, and economic reasons. So far, LoRaWANs have been planned and deployed mainly with the aim of minimizing the number of gateways, while still providing coverage in a geographic area. Packet collisions and future traffic have not been considered. In contrast, we present a gateway placement strategy that is robust against an increase in the number of sensors and in the network load. To this end, we modify an existing local search algorithm for a geometric set cover problem such that it takes the capacities of gateways into account. If we set these capacities below the maximum, the network can accommodate additional sensors in the future. Moreover, our algorithm can extend the initial placement once the capacities are exhausted.

@inproceedings{info3-inproceedings-2021-20, abstract = {Many exciting applications are currently emerging due to the use of technology from the Internet of Things (IoT) in Smart Cities. In recent years, Long Range Wide Area Networks (LoRaWANs) have become one of the main technologies in this field due to long distance coverage, low power consumption sensors, and economic reasons. So far, LoRaWANs have been planned and deployed mainly with the aim of minimizing the number of gateways, while still providing coverage in a geographic area. Packet collisions and future traffic have not been considered. In contrast, we present a gateway placement strategy that is robust against an increase in the number of sensors and in the network load. To this end, we modify an existing local search algorithm for a geometric set cover problem such that it takes the capacities of gateways into account. If we set these capacities below the maximum, the network can accommodate additional sensors in the future. Moreover, our algorithm can extend the initial placement once the capacities are exhausted.}, author = {Loh, Frank and Bau, Dominique and Zink, Johannes and Wolff, Alexander and Hoßfeld, Tobias}, booktitle = {13th IFIP Wireless and Mobile Networking Conference (WMNC)}, keywords = {5mart}, month = 10, title = {Robust Gateway Placement for Scalable LoRaWAN}, year = 2021 }

%0 Conference Paper %1 info3-inproceedings-2021-20 %A Loh, Frank %A Bau, Dominique %A Zink, Johannes %A Wolff, Alexander %A Hoßfeld, Tobias %B 13th IFIP Wireless and Mobile Networking Conference (WMNC) %D 2021 %T Robust Gateway Placement for Scalable LoRaWAN %X Many exciting applications are currently emerging due to the use of technology from the Internet of Things (IoT) in Smart Cities. In recent years, Long Range Wide Area Networks (LoRaWANs) have become one of the main technologies in this field due to long distance coverage, low power consumption sensors, and economic reasons. So far, LoRaWANs have been planned and deployed mainly with the aim of minimizing the number of gateways, while still providing coverage in a geographic area. Packet collisions and future traffic have not been considered. In contrast, we present a gateway placement strategy that is robust against an increase in the number of sensors and in the network load. To this end, we modify an existing local search algorithm for a geometric set cover problem such that it takes the capacities of gateways into account. If we set these capacities below the maximum, the network can accommodate additional sensors in the future. Moreover, our algorithm can extend the initial placement once the capacities are exhausted.
Discrete-time Analysis of Multicomponent GI/GI/1 Queueing Networks Geissler, Stefan; Lange, Stanislav; Tran-Gia, Phuoc; Hoßfeld, Tobias in Conference on Networked Systems (NetSys) (2021).
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In this work, we provide initial insights regarding the error introduced into multicomponent queueing systems by assuming the departure processes of arbitrary GI/GI/1-∞ queues to be renewal processes. To this end, we compute the sojourn time distribution as well as departure distributions of a linear chain of queueing components and compare the results to a simulation of the same system. By applying the renewal approximation, potential autocorrelations of the departure processes are lost. We investigate the magnitude of this error regarding both the sojourn time as well as interdeparture time distributions for a broad set of parameters. Although more indepth studies are needed, our results show that both distributions can be closely approximated, which allows the application of the model to asses the performance of real world NFV function chains.

@inproceedings{info3-inproceedings-2021-4, abstract = {In this work, we provide initial insights regarding the error introduced into multicomponent queueing systems by assuming the departure processes of arbitrary GI/GI/1-∞ queues to be renewal processes. To this end, we compute the sojourn time distribution as well as departure distributions of a linear chain of queueing components and compare the results to a simulation of the same system. By applying the renewal approximation, potential autocorrelations of the departure processes are lost. We investigate the magnitude of this error regarding both the sojourn time as well as interdeparture time distributions for a broad set of parameters. Although more indepth studies are needed, our results show that both distributions can be closely approximated, which allows the application of the model to asses the performance of real world NFV function chains.}, author = {Geissler, Stefan and Lange, Stanislav and Tran-Gia, Phuoc and Hoßfeld, Tobias}, booktitle = {Conference on Networked Systems (NetSys)}, keywords = {sys:hidden:inproceedings}, month = 11, title = {Discrete-time Analysis of Multicomponent GI/GI/1 Queueing Networks}, year = 2021 }

%0 Conference Paper %1 info3-inproceedings-2021-4 %A Geissler, Stefan %A Lange, Stanislav %A Tran-Gia, Phuoc %A Hoßfeld, Tobias %B Conference on Networked Systems (NetSys) %D 2021 %T Discrete-time Analysis of Multicomponent GI/GI/1 Queueing Networks %X In this work, we provide initial insights regarding the error introduced into multicomponent queueing systems by assuming the departure processes of arbitrary GI/GI/1-∞ queues to be renewal processes. To this end, we compute the sojourn time distribution as well as departure distributions of a linear chain of queueing components and compare the results to a simulation of the same system. By applying the renewal approximation, potential autocorrelations of the departure processes are lost. We investigate the magnitude of this error regarding both the sojourn time as well as interdeparture time distributions for a broad set of parameters. Although more indepth studies are needed, our results show that both distributions can be closely approximated, which allows the application of the model to asses the performance of real world NFV function chains.
ML-Assisted Latency Assignments in Time-Sensitive Networking Grigorjew, Alexej; Seufert, Michael; Wehner, Nikolas; Hofmann, Jan; Hoßfeld, Tobias in IFIP/IEEE International Symposium on Integrated Network Management (IM 2021) (2021).
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- [ BibTeX ]
- [ EndNote ]
Recent developments in industrial automation and invehicle communication have raised the requirements of real-time networking. Bus systems that were traditionally deployed in these fields cannot provide sufficient bandwidth and are now shifting towards Ethernet for their real-time communication needs. In this field, standardization efforts from the IEEE and the IETF have developed new data plane mechanisms such as shapers and schedulers, as well as control plane mechanisms such as reservation protocols to support their new requirements. However, their implementation and their optimal configuration remain an important factor for their efficiency. This work presents a machine learning framework that takes on the configuration task. Four different models are trained for the configuration of per-hop latency guarantees in a distributed resource reservation process and compared with respect to their real-time traffic capacity. The evaluation shows that all models provide good configurations for the provided scenarios, but more importantly, they represent a first step for a semi-automated configuration of parameters in Time-Sensitive Networking.

@inproceedings{info3-inproceedings-2021-2, abstract = {Recent developments in industrial automation and invehicle communication have raised the requirements of real-time networking. Bus systems that were traditionally deployed in these fields cannot provide sufficient bandwidth and are now shifting towards Ethernet for their real-time communication needs. In this field, standardization efforts from the IEEE and the IETF have developed new data plane mechanisms such as shapers and schedulers, as well as control plane mechanisms such as reservation protocols to support their new requirements. However, their implementation and their optimal configuration remain an important factor for their efficiency. This work presents a machine learning framework that takes on the configuration task. Four different models are trained for the configuration of per-hop latency guarantees in a distributed resource reservation process and compared with respect to their real-time traffic capacity. The evaluation shows that all models provide good configurations for the provided scenarios, but more importantly, they represent a first step for a semi-automated configuration of parameters in Time-Sensitive Networking.}, address = {Bordeaux, France (Virtual Conference)}, author = {Grigorjew, Alexej and Seufert, Michael and Wehner, Nikolas and Hofmann, Jan and Hoßfeld, Tobias}, booktitle = {IFIP/IEEE International Symposium on Integrated Network Management (IM 2021)}, keywords = {kikdin}, month = 5, title = {ML-Assisted Latency Assignments in Time-Sensitive Networking}, year = 2021 }

%0 Conference Paper %1 info3-inproceedings-2021-2 %A Grigorjew, Alexej %A Seufert, Michael %A Wehner, Nikolas %A Hofmann, Jan %A Hoßfeld, Tobias %B IFIP/IEEE International Symposium on Integrated Network Management (IM 2021) %C Bordeaux, France (Virtual Conference) %D 2021 %T ML-Assisted Latency Assignments in Time-Sensitive Networking %X Recent developments in industrial automation and invehicle communication have raised the requirements of real-time networking. Bus systems that were traditionally deployed in these fields cannot provide sufficient bandwidth and are now shifting towards Ethernet for their real-time communication needs. In this field, standardization efforts from the IEEE and the IETF have developed new data plane mechanisms such as shapers and schedulers, as well as control plane mechanisms such as reservation protocols to support their new requirements. However, their implementation and their optimal configuration remain an important factor for their efficiency. This work presents a machine learning framework that takes on the configuration task. Four different models are trained for the configuration of per-hop latency guarantees in a distributed resource reservation process and compared with respect to their real-time traffic capacity. The evaluation shows that all models provide good configurations for the provided scenarios, but more importantly, they represent a first step for a semi-automated configuration of parameters in Time-Sensitive Networking.
Signaling Traffic in Internet-of-Things Mobile Networks Geissler, Stefan; Wamser, Florian; Bauer, Wolfang; Krolikowski, Michael; Gebert, Steffen; Hoßfeld, Tobias in IFIP/IEEE International Symposium on Integrated Network Management (IM 2021) (2021).
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The Internet of Things (IoT) is expected to play an increasingly important role in next-generation mobile networks. Detailed knowledge of this type of traffic and the associated signaling in those networks is of interest to operators and standardization in order to run these networks successfully. The aim of this study is to characterize IoT signaling traffic for mobile communication networks (i) from a network operator’s point of view, (ii) at device level, and (iii) for the establishment of data connections. General statistics on signaling and device behavior, such as the observed IoT traffic volume and message composition, are given before device classes with statistically different signaling behavior are identified. Finally, by characterizing the aggre- gated signaling traffic, we show that the Markov assumption, widespread in standardization and literature, regarding the aggregated arrival process for data connections does not apply in reality.

@inproceedings{info3-inproceedings-2021-1, abstract = {The Internet of Things (IoT) is expected to play an increasingly important role in next-generation mobile networks. Detailed knowledge of this type of traffic and the associated signaling in those networks is of interest to operators and standardization in order to run these networks successfully. The aim of this study is to characterize IoT signaling traffic for mobile communication networks (i) from a network operator’s point of view, (ii) at device level, and (iii) for the establishment of data connections. General statistics on signaling and device behavior, such as the observed IoT traffic volume and message composition, are given before device classes with statistically different signaling behavior are identified. Finally, by characterizing the aggre- gated signaling traffic, we show that the Markov assumption, widespread in standardization and literature, regarding the aggregated arrival process for data connections does not apply in reality.}, address = {Bordeaux, France (Virtual Conference)}, author = {Geissler, Stefan and Wamser, Florian and Bauer, Wolfang and Krolikowski, Michael and Gebert, Steffen and Hoßfeld, Tobias}, booktitle = {IFIP/IEEE International Symposium on Integrated Network Management (IM 2021)}, keywords = {can}, month = 5, title = {Signaling Traffic in Internet-of-Things Mobile Networks}, year = 2021 }

%0 Conference Paper %1 info3-inproceedings-2021-1 %A Geissler, Stefan %A Wamser, Florian %A Bauer, Wolfang %A Krolikowski, Michael %A Gebert, Steffen %A Hoßfeld, Tobias %B IFIP/IEEE International Symposium on Integrated Network Management (IM 2021) %C Bordeaux, France (Virtual Conference) %D 2021 %T Signaling Traffic in Internet-of-Things Mobile Networks %X The Internet of Things (IoT) is expected to play an increasingly important role in next-generation mobile networks. Detailed knowledge of this type of traffic and the associated signaling in those networks is of interest to operators and standardization in order to run these networks successfully. The aim of this study is to characterize IoT signaling traffic for mobile communication networks (i) from a network operator’s point of view, (ii) at device level, and (iii) for the establishment of data connections. General statistics on signaling and device behavior, such as the observed IoT traffic volume and message composition, are given before device classes with statistically different signaling behavior are identified. Finally, by characterizing the aggre- gated signaling traffic, we show that the Markov assumption, widespread in standardization and literature, regarding the aggregated arrival process for data connections does not apply in reality.
High Performance Network Metadata Extraction Using P4 for ML-Based Intrusion Detection Systems Gray, Nicholas; Dietz, Katharina; Seufert, Michael; Hoßfeld, Tobias in 22nd International Conference on High Performance Switching and Routing (HPSR) (2021).
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@inproceedings{info3-inproceedings-2021-8, address = {Paris, France (Virtual Conference)}, author = {Gray, Nicholas and Dietz, Katharina and Seufert, Michael and Hoßfeld, Tobias}, booktitle = {22nd International Conference on High Performance Switching and Routing (HPSR)}, keywords = {ucn}, month = 6, title = {High Performance Network Metadata Extraction Using P4 for ML-Based Intrusion Detection Systems}, year = 2021 }

%0 Conference Paper %1 info3-inproceedings-2021-8 %A Gray, Nicholas %A Dietz, Katharina %A Seufert, Michael %A Hoßfeld, Tobias %B 22nd International Conference on High Performance Switching and Routing (HPSR) %C Paris, France (Virtual Conference) %D 2021 %T High Performance Network Metadata Extraction Using P4 for ML-Based Intrusion Detection Systems
QoE Models in the Wild: Comparing Video QoE Models Using a Crowdsourced Data Set Seufert, Anika; Wamser, Florian; Yarish, David; Macdonald, Hunter; Hoßfeld, Tobias in 2021 13th International Conference on Quality of Multimedia Experience (QoMEX) (2021).
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Crowdsourced measurements solve the problem of being able to assess the performance of a communication network from an end-user perspective, but the new characteristics of the data pose new challenges for QoE modeling. In contrast to existing laboratory or network measurements, this type of measurement at the end-user device primarily involves taking a large number of short sample measurements, which, however, are rich in measured parameters, including many user-, application-, and device-related parameters. To test the applicability and to facilitate the integration of such data, we applied four QoE models from the literature to 290k worldwide video streaming measurements from a commercial data set from August to October 2020. In this work, we will therefore first describe the crowdsourcing video streaming data set to provide insights into the properties of video streaming KPIs in the real-world. Second, we run four popular QoE models using this data set, compare the resulting QoE scores, and derive the impact of individual KPIs for each model. We show that the models assess the QoE at least differently, but sometimes with contradicting statements. Reading this paper, it becomes evident that more work and subjective studies, based on real-world data like the one we have shown, are needed to extend the current QoE models.

@inproceedings{info3-inproceedings-2021-12, abstract = {Crowdsourced measurements solve the problem of being able to assess the performance of a communication network from an end-user perspective, but the new characteristics of the data pose new challenges for QoE modeling. In contrast to existing laboratory or network measurements, this type of measurement at the end-user device primarily involves taking a large number of short sample measurements, which, however, are rich in measured parameters, including many user-, application-, and device-related parameters. To test the applicability and to facilitate the integration of such data, we applied four QoE models from the literature to 290k worldwide video streaming measurements from a commercial data set from August to October 2020. In this work, we will therefore first describe the crowdsourcing video streaming data set to provide insights into the properties of video streaming KPIs in the real-world. Second, we run four popular QoE models using this data set, compare the resulting QoE scores, and derive the impact of individual KPIs for each model. We show that the models assess the QoE at least differently, but sometimes with contradicting statements. Reading this paper, it becomes evident that more work and subjective studies, based on real-world data like the one we have shown, are needed to extend the current QoE models.}, address = {Montreal, Canada (virtual conference)}, author = {Seufert, Anika and Wamser, Florian and Yarish, David and Macdonald, Hunter and Hoßfeld, Tobias}, booktitle = {2021 13th International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {can}, month = 6, title = {QoE Models in the Wild: Comparing Video QoE Models Using a Crowdsourced Data Set}, year = 2021 }

%0 Conference Paper %1 info3-inproceedings-2021-12 %A Seufert, Anika %A Wamser, Florian %A Yarish, David %A Macdonald, Hunter %A Hoßfeld, Tobias %B 2021 13th International Conference on Quality of Multimedia Experience (QoMEX) %C Montreal, Canada (virtual conference) %D 2021 %T QoE Models in the Wild: Comparing Video QoE Models Using a Crowdsourced Data Set %X Crowdsourced measurements solve the problem of being able to assess the performance of a communication network from an end-user perspective, but the new characteristics of the data pose new challenges for QoE modeling. In contrast to existing laboratory or network measurements, this type of measurement at the end-user device primarily involves taking a large number of short sample measurements, which, however, are rich in measured parameters, including many user-, application-, and device-related parameters. To test the applicability and to facilitate the integration of such data, we applied four QoE models from the literature to 290k worldwide video streaming measurements from a commercial data set from August to October 2020. In this work, we will therefore first describe the crowdsourcing video streaming data set to provide insights into the properties of video streaming KPIs in the real-world. Second, we run four popular QoE models using this data set, compare the resulting QoE scores, and derive the impact of individual KPIs for each model. We show that the models assess the QoE at least differently, but sometimes with contradicting statements. Reading this paper, it becomes evident that more work and subjective studies, based on real-world data like the one we have shown, are needed to extend the current QoE models.
How are your Apps Doing? QoE Inference and Analysis in Mobile Devices Wehner, Nikolas; Seufert, Michael; Schüler, Joshua; Casas, Pedro; Hoßfeld, Tobias in 17th International Conference on Network and Service Management (CNSM) (2021).
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Web browsing has become the most important application of the Internet for the end user. When it comes to mobile devices, web services are mainly accessed through apps. This paper tackles the problem of Web Quality of Experience (QoE) in mobile devices, with a specific focus on apps QoE monitoring and analysis, using in-network (encrypted) traffic measurements. Measuring apps QoE is complex, not only from an instrumentation point of view, but also from the heterogeneity of user interactions which might realize substantially different user experience. To this end, we conduct a feasibility study on four specific and popular Android apps and their corresponding web services. Our test automation framework emulates and measures different user interactions commonly executed during an app session, including the app startup, clicking, scrolling, and searching. The resulting traffic is characterized on different dimensions, and machine learning models are trained to identify web services, apps, and user interactions, and to infer their QoE. The proposed models can correctly identify the specific web service and app in 86% of the cases and accurately estimate the associated QoE with small errors. Our preliminary study represents a first step towards an in-network, web QoE monitoring solution for mobile-device apps.

@inproceedings{info3-inproceedings-2021-15, abstract = {Web browsing has become the most important application of the Internet for the end user. When it comes to mobile devices, web services are mainly accessed through apps. This paper tackles the problem of Web Quality of Experience (QoE) in mobile devices, with a specific focus on apps QoE monitoring and analysis, using in-network (encrypted) traffic measurements. Measuring apps QoE is complex, not only from an instrumentation point of view, but also from the heterogeneity of user interactions which might realize substantially different user experience. To this end, we conduct a feasibility study on four specific and popular Android apps and their corresponding web services. Our test automation framework emulates and measures different user interactions commonly executed during an app session, including the app startup, clicking, scrolling, and searching. The resulting traffic is characterized on different dimensions, and machine learning models are trained to identify web services, apps, and user interactions, and to infer their QoE. The proposed models can correctly identify the specific web service and app in 86% of the cases and accurately estimate the associated QoE with small errors. Our preliminary study represents a first step towards an in-network, web QoE monitoring solution for mobile-device apps.}, address = {Izmir, Turkey (Virtual Conference)}, author = {Wehner, Nikolas and Seufert, Michael and Schüler, Joshua and Casas, Pedro and Hoßfeld, Tobias}, booktitle = {17th International Conference on Network and Service Management (CNSM)}, keywords = {ucn}, month = 10, title = {How are your Apps Doing? QoE Inference and Analysis in Mobile Devices}, year = 2021 }

%0 Conference Paper %1 info3-inproceedings-2021-15 %A Wehner, Nikolas %A Seufert, Michael %A Schüler, Joshua %A Casas, Pedro %A Hoßfeld, Tobias %B 17th International Conference on Network and Service Management (CNSM) %C Izmir, Turkey (Virtual Conference) %D 2021 %T How are your Apps Doing? QoE Inference and Analysis in Mobile Devices %X Web browsing has become the most important application of the Internet for the end user. When it comes to mobile devices, web services are mainly accessed through apps. This paper tackles the problem of Web Quality of Experience (QoE) in mobile devices, with a specific focus on apps QoE monitoring and analysis, using in-network (encrypted) traffic measurements. Measuring apps QoE is complex, not only from an instrumentation point of view, but also from the heterogeneity of user interactions which might realize substantially different user experience. To this end, we conduct a feasibility study on four specific and popular Android apps and their corresponding web services. Our test automation framework emulates and measures different user interactions commonly executed during an app session, including the app startup, clicking, scrolling, and searching. The resulting traffic is characterized on different dimensions, and machine learning models are trained to identify web services, apps, and user interactions, and to infer their QoE. The proposed models can correctly identify the specific web service and app in 86% of the cases and accurately estimate the associated QoE with small errors. Our preliminary study represents a first step towards an in-network, web QoE monitoring solution for mobile-device apps.
Browser Fingerprinting: How to Protect Machine Learning Models and Data with Differential Privacy? Dietz, Katharina; Mühlhauser, Michael; Seufert, Michael; Gray, Nicholas; Hoßfeld, Tobias; Herrmann, Dominik in 1st International Workshop on Machine Learning in Networking (MaLeNe) (2021).
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@inproceedings{info3-inproceedings-2021-16, address = {Lübeck, Germany (Virtual Conference)}, author = {Dietz, Katharina and Mühlhauser, Michael and Seufert, Michael and Gray, Nicholas and Hoßfeld, Tobias and Herrmann, Dominik}, booktitle = {1st International Workshop on Machine Learning in Networking (MaLeNe)}, keywords = {ucn}, month = 9, title = {Browser Fingerprinting: How to Protect Machine Learning Models and Data with Differential Privacy?}, year = 2021 }

%0 Conference Paper %1 info3-inproceedings-2021-16 %A Dietz, Katharina %A Mühlhauser, Michael %A Seufert, Michael %A Gray, Nicholas %A Hoßfeld, Tobias %A Herrmann, Dominik %B 1st International Workshop on Machine Learning in Networking (MaLeNe) %C Lübeck, Germany (Virtual Conference) %D 2021 %T Browser Fingerprinting: How to Protect Machine Learning Models and Data with Differential Privacy?
Talk to Me: Investigating the Traffic Characteristics of Amazon Echo Dot and Google Home Loh, Frank; Geissler, Stefan; Schaible, Fabian; Hoßfeld, Tobias in International Conference on Communications and Electronics, ICCE (2021).
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The application area of smart speakers is steadily increasing with the Amazon Echo family and Google Home being brand leaders. Use cases include, among others, updating the calendar, home automation, or simply assisting users in their every day life. With the increasing amount of devices, the traffic generation and requesting process becomes a relevant subject to be studied in order to create traffic models and predict the impact on networks by these types of devices. Furthermore, with a detailed understanding of the devices, service quality can be monitored and improved for the end user. For that reason, in this work the requesting and traffic generation process of the Amazon Echo Dot and Google Home are studied and the generated network load of both devices is compared. With the insights of this study and additional device usage statistics, detailed traffic and usage models can be created.

@inproceedings{info3-inproceedings-2021-5, abstract = {The application area of smart speakers is steadily increasing with the Amazon Echo family and Google Home being brand leaders. Use cases include, among others, updating the calendar, home automation, or simply assisting users in their every day life. With the increasing amount of devices, the traffic generation and requesting process becomes a relevant subject to be studied in order to create traffic models and predict the impact on networks by these types of devices. Furthermore, with a detailed understanding of the devices, service quality can be monitored and improved for the end user. For that reason, in this work the requesting and traffic generation process of the Amazon Echo Dot and Google Home are studied and the generated network load of both devices is compared. With the insights of this study and additional device usage statistics, detailed traffic and usage models can be created.}, author = {Loh, Frank and Geissler, Stefan and Schaible, Fabian and Hoßfeld, Tobias}, booktitle = {International Conference on Communications and Electronics, ICCE}, keywords = {sys:hidden:inproceedings}, month = 1, title = {Talk to Me: Investigating the Traffic Characteristics of Amazon Echo Dot and Google Home}, year = 2021 }

%0 Conference Paper %1 info3-inproceedings-2021-5 %A Loh, Frank %A Geissler, Stefan %A Schaible, Fabian %A Hoßfeld, Tobias %B International Conference on Communications and Electronics, ICCE %D 2021 %T Talk to Me: Investigating the Traffic Characteristics of Amazon Echo Dot and Google Home %X The application area of smart speakers is steadily increasing with the Amazon Echo family and Google Home being brand leaders. Use cases include, among others, updating the calendar, home automation, or simply assisting users in their every day life. With the increasing amount of devices, the traffic generation and requesting process becomes a relevant subject to be studied in order to create traffic models and predict the impact on networks by these types of devices. Furthermore, with a detailed understanding of the devices, service quality can be monitored and improved for the end user. For that reason, in this work the requesting and traffic generation process of the Amazon Echo Dot and Google Home are studied and the generated network load of both devices is compared. With the insights of this study and additional device usage statistics, detailed traffic and usage models can be created.
Trust but Verify: Crowdsourced Mobile Network Measurements and Statistical Validity Measures Seufert, Anika; Wamser, Florian; Wunderer, Stefan; Hall, Andrew; Hoßfeld, Tobias in 2021 Joint European Conference on Networks and Communications & 6G Summit (EuCNC/6G Summit) (2021).
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Network operators, regulators, and big data companies use crowdsourced measurements to study the performance of mobile networks on a large scale. Such a type of measurement is defined as the collection and processing of data measured by the crowd, here the crowd of mobile subscribers. Crowdsourced network measurements make it relatively easy and inexpensive to obtain large amounts of network data that also reflect the quality actually received by the end user. However, this measurement method also involves some uncertainties, since, for example, it is not possible to precisely control when, where and with which devices measurements are taken. Thus, there is a trade-off between the reliability of the individual measurement and the scope of the measurements. Therefore, how data of this type is analyzed is particularly important in order to obtain valid results. To address this issue, our paper defines concepts and guidelines for analyzing the validity of crowdsourced mobile network measurements. In particular, we address precision, for example the number of measurements needed to make valid statements, and also representativeness, for example the spatial and temporal distribution of the data. In addition to the formal definition of these two aspects, we illustrate the issue and possible evaluation approaches with the help of an extensive example data set. This data set consists of more than 11.7M crowdsourced mobile measurements from all over France, measured by a commercial mobile data provider. In the end, we provide an evaluation guideline and two possible use cases.

@inproceedings{info3-inproceedings-2021-11, abstract = {Network operators, regulators, and big data companies use crowdsourced measurements to study the performance of mobile networks on a large scale. Such a type of measurement is defined as the collection and processing of data measured by the crowd, here the crowd of mobile subscribers. Crowdsourced network measurements make it relatively easy and inexpensive to obtain large amounts of network data that also reflect the quality actually received by the end user. However, this measurement method also involves some uncertainties, since, for example, it is not possible to precisely control when, where and with which devices measurements are taken. Thus, there is a trade-off between the reliability of the individual measurement and the scope of the measurements. Therefore, how data of this type is analyzed is particularly important in order to obtain valid results. To address this issue, our paper defines concepts and guidelines for analyzing the validity of crowdsourced mobile network measurements. In particular, we address precision, for example the number of measurements needed to make valid statements, and also representativeness, for example the spatial and temporal distribution of the data. In addition to the formal definition of these two aspects, we illustrate the issue and possible evaluation approaches with the help of an extensive example data set. This data set consists of more than 11.7M crowdsourced mobile measurements from all over France, measured by a commercial mobile data provider. In the end, we provide an evaluation guideline and two possible use cases.}, address = {Porto, Portugal (virtual conference)}, author = {Seufert, Anika and Wamser, Florian and Wunderer, Stefan and Hall, Andrew and Hoßfeld, Tobias}, booktitle = {2021 Joint European Conference on Networks and Communications & 6G Summit (EuCNC/6G Summit)}, keywords = {can}, month = 6, title = {Trust but Verify: Crowdsourced Mobile Network Measurements and Statistical Validity Measures}, year = 2021 }

%0 Conference Paper %1 info3-inproceedings-2021-11 %A Seufert, Anika %A Wamser, Florian %A Wunderer, Stefan %A Hall, Andrew %A Hoßfeld, Tobias %B 2021 Joint European Conference on Networks and Communications & 6G Summit (EuCNC/6G Summit) %C Porto, Portugal (virtual conference) %D 2021 %T Trust but Verify: Crowdsourced Mobile Network Measurements and Statistical Validity Measures %X Network operators, regulators, and big data companies use crowdsourced measurements to study the performance of mobile networks on a large scale. Such a type of measurement is defined as the collection and processing of data measured by the crowd, here the crowd of mobile subscribers. Crowdsourced network measurements make it relatively easy and inexpensive to obtain large amounts of network data that also reflect the quality actually received by the end user. However, this measurement method also involves some uncertainties, since, for example, it is not possible to precisely control when, where and with which devices measurements are taken. Thus, there is a trade-off between the reliability of the individual measurement and the scope of the measurements. Therefore, how data of this type is analyzed is particularly important in order to obtain valid results. To address this issue, our paper defines concepts and guidelines for analyzing the validity of crowdsourced mobile network measurements. In particular, we address precision, for example the number of measurements needed to make valid statements, and also representativeness, for example the spatial and temporal distribution of the data. In addition to the formal definition of these two aspects, we illustrate the issue and possible evaluation approaches with the help of an extensive example data set. This data set consists of more than 11.7M crowdsourced mobile measurements from all over France, measured by a commercial mobile data provider. In the end, we provide an evaluation guideline and two possible use cases.
Dynamic Real-Time Stream Reservation with TAS and Shared Time Windows Grigorjew, Alexej; Gray, Nicholas; Hoßfeld, Tobias in 2nd International Workshop on Time-Sensitive and Deterministic Networking (TENSOR) (2021).
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Motivated by new use cases such as industrial automation and in-vehicle communication, Time-Sensitive Networking is further improving the layer~2 standards for real-time communication in Ethernet networks. As periodic traffic is a common requirement in such scenarios, the Time Aware Shaper (TAS) is a highly popular mechanism that allows the realization of real-time guarantees in synchronized networks. Most applications in literature suggest to configure the TAS for full stream isolation such that the lowest delays can be achieved. However, this ``zero-queuing'' strategy requires a high amount of computational resources and time, as the configuration of the gate control lists of each port is a complex task, which is not suitable for scenarios with dynamically changing requirements. This paper presents a novel approach with shared time windows. In combination with stream reservation techniques that are commonly applied for asynchronous mechanisms, the network is able to accept new streams during operation without complex reconfiguration, while still benefiting from some degree of isolation compared to conventional asynchronous shapers. The evaluation shows that, given the right circumstances, the number of accepted real-time streams can be improved significantly.

@inproceedings{info3-inproceedings-2021-7, abstract = {Motivated by new use cases such as industrial automation and in-vehicle communication, Time-Sensitive Networking is further improving the layer 2 standards for real-time communication in Ethernet networks. As periodic traffic is a common requirement in such scenarios, the Time Aware Shaper (TAS) is a highly popular mechanism that allows the realization of real-time guarantees in synchronized networks. Most applications in literature suggest to configure the TAS for full stream isolation such that the lowest delays can be achieved. However, this ``zero-queuing'' strategy requires a high amount of computational resources and time, as the configuration of the gate control lists of each port is a complex task, which is not suitable for scenarios with dynamically changing requirements. This paper presents a novel approach with shared time windows. In combination with stream reservation techniques that are commonly applied for asynchronous mechanisms, the network is able to accept new streams during operation without complex reconfiguration, while still benefiting from some degree of isolation compared to conventional asynchronous shapers. The evaluation shows that, given the right circumstances, the number of accepted real-time streams can be improved significantly.}, author = {Grigorjew, Alexej and Gray, Nicholas and Hoßfeld, Tobias}, booktitle = {2nd International Workshop on Time-Sensitive and Deterministic Networking (TENSOR)}, keywords = {ngn}, month = 6, title = {Dynamic Real-Time Stream Reservation with TAS and Shared Time Windows}, year = 2021 }

%0 Conference Paper %1 info3-inproceedings-2021-7 %A Grigorjew, Alexej %A Gray, Nicholas %A Hoßfeld, Tobias %B 2nd International Workshop on Time-Sensitive and Deterministic Networking (TENSOR) %D 2021 %T Dynamic Real-Time Stream Reservation with TAS and Shared Time Windows %X Motivated by new use cases such as industrial automation and in-vehicle communication, Time-Sensitive Networking is further improving the layer~2 standards for real-time communication in Ethernet networks. As periodic traffic is a common requirement in such scenarios, the Time Aware Shaper (TAS) is a highly popular mechanism that allows the realization of real-time guarantees in synchronized networks. Most applications in literature suggest to configure the TAS for full stream isolation such that the lowest delays can be achieved. However, this ``zero-queuing'' strategy requires a high amount of computational resources and time, as the configuration of the gate control lists of each port is a complex task, which is not suitable for scenarios with dynamically changing requirements. This paper presents a novel approach with shared time windows. In combination with stream reservation techniques that are commonly applied for asynchronous mechanisms, the network is able to accept new streams during operation without complex reconfiguration, while still benefiting from some degree of isolation compared to conventional asynchronous shapers. The evaluation shows that, given the right circumstances, the number of accepted real-time streams can be improved significantly.
Improving LoRaWAN’s Successful Information Transmission Rate with Redundancy Loh, Frank; Raffeck, Simon; Metzger, Florian; Hoßfeld, Tobias in 17th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob) (2021).
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The adaptation of Internet of Things in our everyday life shows different new demands and challenges. One of the fastest growing technologies in this context are Low Power Wide Area Networks with LoRaWAN as one of their most prominent representatives. The promise of this technology is to transmit sensor data over large distances with very little energy consumption. But transmission behavior, and especially overhead and collision probability, must be studied in detail to improve transmission quality and energy consumption due to the random access nature of LoRaWAN. Because of that, this work investigates the LoRaWAN channel capacity by analyzing the transmission overhead, the collision probability, and the data loss. At the end, an energy consumption comparison is done. The contribution is a novel approach based on aggregation and retransmission that shows a decreased data loss of up to 20% compared to the currently used random channel access.

@inproceedings{info3-inproceedings-2021-19, abstract = {The adaptation of Internet of Things in our everyday life shows different new demands and challenges. One of the fastest growing technologies in this context are Low Power Wide Area Networks with LoRaWAN as one of their most prominent representatives. The promise of this technology is to transmit sensor data over large distances with very little energy consumption. But transmission behavior, and especially overhead and collision probability, must be studied in detail to improve transmission quality and energy consumption due to the random access nature of LoRaWAN. Because of that, this work investigates the LoRaWAN channel capacity by analyzing the transmission overhead, the collision probability, and the data loss. At the end, an energy consumption comparison is done. The contribution is a novel approach based on aggregation and retransmission that shows a decreased data loss of up to 20% compared to the currently used random channel access.}, author = {Loh, Frank and Raffeck, Simon and Metzger, Florian and Hoßfeld, Tobias}, booktitle = {17th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob)}, keywords = {5mart}, month = 10, title = {Improving LoRaWAN’s Successful Information Transmission Rate with Redundancy}, year = 2021 }

%0 Conference Paper %1 info3-inproceedings-2021-19 %A Loh, Frank %A Raffeck, Simon %A Metzger, Florian %A Hoßfeld, Tobias %B 17th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob) %D 2021 %T Improving LoRaWAN’s Successful Information Transmission Rate with Redundancy %X The adaptation of Internet of Things in our everyday life shows different new demands and challenges. One of the fastest growing technologies in this context are Low Power Wide Area Networks with LoRaWAN as one of their most prominent representatives. The promise of this technology is to transmit sensor data over large distances with very little energy consumption. But transmission behavior, and especially overhead and collision probability, must be studied in detail to improve transmission quality and energy consumption due to the random access nature of LoRaWAN. Because of that, this work investigates the LoRaWAN channel capacity by analyzing the transmission overhead, the collision probability, and the data loss. At the end, an energy consumption comparison is done. The contribution is a novel approach based on aggregation and retransmission that shows a decreased data loss of up to 20% compared to the currently used random channel access.
Mobile Web and App QoE Monitoring for ISPs - from Encrypted Traffic to Speed Index through Machine Learning Casas, Pedro; Wassermann, Sarah; Wehner, Nikolas; Seufert, Michael; Schüler, Joshua; Hoßfeld, Tobias in 13th Wireless and Mobile Networking Conference (WMNC), Best Paper Award (2021).
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@inproceedings{info3-inproceedings-2021-17, address = {Montreal, Canada (Virtual Conference)}, author = {Casas, Pedro and Wassermann, Sarah and Wehner, Nikolas and Seufert, Michael and Schüler, Joshua and Hoßfeld, Tobias}, booktitle = {13th Wireless and Mobile Networking Conference (WMNC), Best Paper Award}, keywords = {ucn}, month = 10, title = {Mobile Web and App QoE Monitoring for ISPs - from Encrypted Traffic to Speed Index through Machine Learning}, year = 2021 }

%0 Conference Paper %1 info3-inproceedings-2021-17 %A Casas, Pedro %A Wassermann, Sarah %A Wehner, Nikolas %A Seufert, Michael %A Schüler, Joshua %A Hoßfeld, Tobias %B 13th Wireless and Mobile Networking Conference (WMNC), Best Paper Award %C Montreal, Canada (Virtual Conference) %D 2021 %T Mobile Web and App QoE Monitoring for ISPs - from Encrypted Traffic to Speed Index through Machine Learning
Distributed Implementation of Deterministic Networking in Existing Non-TSN Ethernet Switches Grigorjew, Alexej; Baier, Christian; Metzger, Florian; Hoßfeld, Tobias in Workshop on Time-sensitive and Deterministic Networking (TsDN) (2021).
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Deterministic networking is quickly gaining importance, as several domains previously dominated by bus systems are now switching to Ethernet. While standardization efforts, especially from the Time-Sensitive Networking (TSN) group, are ongoing, practical deployments are still far off until configuration guidelines and resource management are able to use these tools to their full potential. As an alternative, this work presents a working implementation of bounded latency with an off-the-shelf non-TSN Ethernet switch. The solution is based on a distributed reservation protocol and admission control. It proves that bounded latency is already possible with simple priority-based transmission, and it provides valuable insights for the development and operation of future real-time networking solutions.

@inproceedings{info3-inproceedings-2021-6, abstract = {Deterministic networking is quickly gaining importance, as several domains previously dominated by bus systems are now switching to Ethernet. While standardization efforts, especially from the Time-Sensitive Networking (TSN) group, are ongoing, practical deployments are still far off until configuration guidelines and resource management are able to use these tools to their full potential. As an alternative, this work presents a working implementation of bounded latency with an off-the-shelf non-TSN Ethernet switch. The solution is based on a distributed reservation protocol and admission control. It proves that bounded latency is already possible with simple priority-based transmission, and it provides valuable insights for the development and operation of future real-time networking solutions.}, author = {Grigorjew, Alexej and Baier, Christian and Metzger, Florian and Hoßfeld, Tobias}, booktitle = {Workshop on Time-sensitive and Deterministic Networking (TsDN)}, keywords = {ats-performance}, month = 6, title = {Distributed Implementation of Deterministic Networking in Existing Non-TSN Ethernet Switches}, year = 2021 }

%0 Conference Paper %1 info3-inproceedings-2021-6 %A Grigorjew, Alexej %A Baier, Christian %A Metzger, Florian %A Hoßfeld, Tobias %B Workshop on Time-sensitive and Deterministic Networking (TsDN) %D 2021 %T Distributed Implementation of Deterministic Networking in Existing Non-TSN Ethernet Switches %X Deterministic networking is quickly gaining importance, as several domains previously dominated by bus systems are now switching to Ethernet. While standardization efforts, especially from the Time-Sensitive Networking (TSN) group, are ongoing, practical deployments are still far off until configuration guidelines and resource management are able to use these tools to their full potential. As an alternative, this work presents a working implementation of bounded latency with an off-the-shelf non-TSN Ethernet switch. The solution is based on a distributed reservation protocol and admission control. It proves that bounded latency is already possible with simple priority-based transmission, and it provides valuable insights for the development and operation of future real-time networking solutions.
Personal Task Design Preferences of Crowdworkers Hirth, Matthias; Borchert, Kathrin; de Moor, Katrien; Borst, Vanessa; Hoßfeld, Tobias in 12th International Conference on Quality of Multimedia Experience (QoMEX) (2020).
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@inproceedings{info3-inproceedings-2020-5, address = {Athlone, Ireland}, author = {Hirth, Matthias and Borchert, Kathrin and de Moor, Katrien and Borst, Vanessa and Hoßfeld, Tobias}, booktitle = {12th International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {ua-net}, month = 5, title = {Personal Task Design Preferences of Crowdworkers}, year = 2020 }

%0 Conference Paper %1 info3-inproceedings-2020-5 %A Hirth, Matthias %A Borchert, Kathrin %A de Moor, Katrien %A Borst, Vanessa %A Hoßfeld, Tobias %B 12th International Conference on Quality of Multimedia Experience (QoMEX) %C Athlone, Ireland %D 2020 %T Personal Task Design Preferences of Crowdworkers
Crowdsourced Network Measurements in Germany: Mobile Internet Experience from End User Perspective Schwind, Anika; Wamser, Florian; Hoßfeld, Tobias; Wunderer, Stefan; Tarnvik, Erik; Hall, Andy in Broadband Coverage in Germany; 14. ITG Symposium (2020).
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Collecting and analyzing meaningful data in mobile networks is the key to assessing network performance. Crowdsourced Network Measurements (CNMs) provide insights beyond the network layer and offer performance and other measurements at the application and user-level towards Quality of Experience (QoE). In this paper, the mobile Internet experience for Germany is evaluated with the help of crowdsourcing from the perspective of an end user. We statistically analyze a dataset with throughput measurements on the end device from Tutela Ltd., which covers more than 2.5 million throughput tests across Germany from January to July 2019. We give insights into this emerging methodology and highlight the benefits of this method. The paper contains statistics and conclusions for several large cities as well as regions in Germany compared to general statements for Germany, since individual measurements and averages often only imprecisely reflect the situation. The goal is to give a holistic view of the performance of the current mobile network in Germany. Reading this paper, it becomes evident that reliable statements about the quality of the mobile network for Germany depend on a large number of peculiarities in different regions with their own performance characteristics due to different network deployments and population numbers.

@inproceedings{info3-inproceedings-2020-13, abstract = {Collecting and analyzing meaningful data in mobile networks is the key to assessing network performance. Crowdsourced Network Measurements (CNMs) provide insights beyond the network layer and offer performance and other measurements at the application and user-level towards Quality of Experience (QoE). In this paper, the mobile Internet experience for Germany is evaluated with the help of crowdsourcing from the perspective of an end user. We statistically analyze a dataset with throughput measurements on the end device from Tutela Ltd., which covers more than 2.5 million throughput tests across Germany from January to July 2019. We give insights into this emerging methodology and highlight the benefits of this method. The paper contains statistics and conclusions for several large cities as well as regions in Germany compared to general statements for Germany, since individual measurements and averages often only imprecisely reflect the situation. The goal is to give a holistic view of the performance of the current mobile network in Germany. Reading this paper, it becomes evident that reliable statements about the quality of the mobile network for Germany depend on a large number of peculiarities in different regions with their own performance characteristics due to different network deployments and population numbers.}, address = {Berlin}, author = {Schwind, Anika and Wamser, Florian and Hoßfeld, Tobias and Wunderer, Stefan and Tarnvik, Erik and Hall, Andy}, booktitle = {Broadband Coverage in Germany; 14. ITG Symposium}, keywords = {can}, month = 8, title = {Crowdsourced Network Measurements in Germany: Mobile Internet Experience from End User Perspective}, year = 2020 }

%0 Conference Paper %1 info3-inproceedings-2020-13 %A Schwind, Anika %A Wamser, Florian %A Hoßfeld, Tobias %A Wunderer, Stefan %A Tarnvik, Erik %A Hall, Andy %B Broadband Coverage in Germany; 14. ITG Symposium %C Berlin %D 2020 %T Crowdsourced Network Measurements in Germany: Mobile Internet Experience from End User Perspective %X Collecting and analyzing meaningful data in mobile networks is the key to assessing network performance. Crowdsourced Network Measurements (CNMs) provide insights beyond the network layer and offer performance and other measurements at the application and user-level towards Quality of Experience (QoE). In this paper, the mobile Internet experience for Germany is evaluated with the help of crowdsourcing from the perspective of an end user. We statistically analyze a dataset with throughput measurements on the end device from Tutela Ltd., which covers more than 2.5 million throughput tests across Germany from January to July 2019. We give insights into this emerging methodology and highlight the benefits of this method. The paper contains statistics and conclusions for several large cities as well as regions in Germany compared to general statements for Germany, since individual measurements and averages often only imprecisely reflect the situation. The goal is to give a holistic view of the performance of the current mobile network in Germany. Reading this paper, it becomes evident that reliable statements about the quality of the mobile network for Germany depend on a large number of peculiarities in different regions with their own performance characteristics due to different network deployments and population numbers.
Improving Web QoE Monitoring for Encrypted Network Traffic through Time Series Modeling Wehner, Nikolas; Seufert, Michael; Schüler, Joshua; Wassermann, Sarah; Casas, Pedro; Hoßfeld, Tobias in 2nd Workshop on AI in Networks and Distributed Systems (WAIN) (2020).
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This paper addresses the problem of Quality of Experience (QoE) monitoring for web browsing. In particular, the inference of common Web QoE metrics such as Speed Index (SI) is investigated. Based on a large dataset collected with open web-measurement platforms on different device-types, a unique feature set is designed and used to estimate the RUMSI -- an efficient approximation to SI, with machine-learning based regression and classification approaches. Results indicate that it is possible to estimate the RUMSI accurately, and that in particular, recurrent neural networks are highly suitable for the task, as they capture the network dynamics more precisely.

@inproceedings{info3-inproceedings-2020-12, abstract = {This paper addresses the problem of Quality of Experience (QoE) monitoring for web browsing. In particular, the inference of common Web QoE metrics such as Speed Index (SI) is investigated. Based on a large dataset collected with open web-measurement platforms on different device-types, a unique feature set is designed and used to estimate the RUMSI – an efficient approximation to SI, with machine-learning based regression and classification approaches. Results indicate that it is possible to estimate the RUMSI accurately, and that in particular, recurrent neural networks are highly suitable for the task, as they capture the network dynamics more precisely.}, address = {Milan, Italy}, author = {Wehner, Nikolas and Seufert, Michael and Schüler, Joshua and Wassermann, Sarah and Casas, Pedro and Hoßfeld, Tobias}, booktitle = {2nd Workshop on AI in Networks and Distributed Systems (WAIN)}, keywords = {ucn}, month = 11, title = {Improving Web QoE Monitoring for Encrypted Network Traffic through Time Series Modeling}, year = 2020 }

%0 Conference Paper %1 info3-inproceedings-2020-12 %A Wehner, Nikolas %A Seufert, Michael %A Schüler, Joshua %A Wassermann, Sarah %A Casas, Pedro %A Hoßfeld, Tobias %B 2nd Workshop on AI in Networks and Distributed Systems (WAIN) %C Milan, Italy %D 2020 %T Improving Web QoE Monitoring for Encrypted Network Traffic through Time Series Modeling %X This paper addresses the problem of Quality of Experience (QoE) monitoring for web browsing. In particular, the inference of common Web QoE metrics such as Speed Index (SI) is investigated. Based on a large dataset collected with open web-measurement platforms on different device-types, a unique feature set is designed and used to estimate the RUMSI -- an efficient approximation to SI, with machine-learning based regression and classification approaches. Results indicate that it is possible to estimate the RUMSI accurately, and that in particular, recurrent neural networks are highly suitable for the task, as they capture the network dynamics more precisely.
Simulative Evaluation of KPIs in SDN for Topology Classification and Performance Prediction Models Gray, Nicholas; Dietz, Katharina; Hoßfeld, Tobias in 2020 16th International Conference on Network and Service Management (CNSM) (2020).
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In recent years Software-defined Networking (SDN) has gained increased popularity by reducing the complexity of management operations and increasing the performance of networks. As a result, the number of purchasable SDN devices and their deployment in real world network constantly rises, making a thorough understanding of their behaviors and interactions even more important. In this work we analyze distributed controller architectures via simulation, identify Key Performance Indicators (KPIs), classify various network topologies with respect to their impact on SDN, as well as create a prediction model to estimate the overall performance of the overall SDN ecosystem, which can be used for network planning.

@inproceedings{info3-inproceedings-2020-15, abstract = {In recent years Software-defined Networking (SDN) has gained increased popularity by reducing the complexity of management operations and increasing the performance of networks. As a result, the number of purchasable SDN devices and their deployment in real world network constantly rises, making a thorough understanding of their behaviors and interactions even more important. In this work we analyze distributed controller architectures via simulation, identify Key Performance Indicators (KPIs), classify various network topologies with respect to their impact on SDN, as well as create a prediction model to estimate the overall performance of the overall SDN ecosystem, which can be used for network planning.}, author = {Gray, Nicholas and Dietz, Katharina and Hoßfeld, Tobias}, booktitle = {2020 16th International Conference on Network and Service Management (CNSM)}, keywords = {sys:hidden:inproceedings}, title = {Simulative Evaluation of KPIs in SDN for Topology Classification and Performance Prediction Models}, year = 2020 }

%0 Conference Paper %1 info3-inproceedings-2020-15 %A Gray, Nicholas %A Dietz, Katharina %A Hoßfeld, Tobias %B 2020 16th International Conference on Network and Service Management (CNSM) %D 2020 %T Simulative Evaluation of KPIs in SDN for Topology Classification and Performance Prediction Models %X In recent years Software-defined Networking (SDN) has gained increased popularity by reducing the complexity of management operations and increasing the performance of networks. As a result, the number of purchasable SDN devices and their deployment in real world network constantly rises, making a thorough understanding of their behaviors and interactions even more important. In this work we analyze distributed controller architectures via simulation, identify Key Performance Indicators (KPIs), classify various network topologies with respect to their impact on SDN, as well as create a prediction model to estimate the overall performance of the overall SDN ecosystem, which can be used for network planning.
Different Points of View: Impact of 3D Point Cloud Reduction on QoE of Rendered Images Seufert, Michael; Kargl, Julian; Schauer, Johannes; Nüchter, Andreas; Hoßfeld, Tobias in 12th International Conference on Quality of Multimedia Experience (QoMEX) (2020).
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Modern photogrammetric methods as well as laser measurement systems make it easy to collect large 3D point clouds that sample objects or environments. As the recorded point clouds can be used to render computer-generated images and models, they are of particular interest in the domains of geographical and architectural engineering, as well for computer graphics (e.g., games or virtual reality). However, point clouds have a huge storage demand, thus, point clouds shall be reduced by removing some of the points. This will inevitably also reduce the Quality of Experience (QoE) of media, which is rendered from the reduced point clouds. In this work, the impact of two different reduction methods on the QoE of rendered images is investigated from two point of views, i.e., based on ratings from both naive crowdworkers as well as point cloud experts.

@inproceedings{info3-inproceedings-2020-4, abstract = {Modern photogrammetric methods as well as laser measurement systems make it easy to collect large 3D point clouds that sample objects or environments. As the recorded point clouds can be used to render computer-generated images and models, they are of particular interest in the domains of geographical and architectural engineering, as well for computer graphics (e.g., games or virtual reality). However, point clouds have a huge storage demand, thus, point clouds shall be reduced by removing some of the points. This will inevitably also reduce the Quality of Experience (QoE) of media, which is rendered from the reduced point clouds. In this work, the impact of two different reduction methods on the QoE of rendered images is investigated from two point of views, i.e., based on ratings from both naive crowdworkers as well as point cloud experts.}, address = {Athlone, Ireland}, author = {Seufert, Michael and Kargl, Julian and Schauer, Johannes and Nüchter, Andreas and Hoßfeld, Tobias}, booktitle = {12th International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {ua-net}, month = 5, title = {Different Points of View: Impact of 3D Point Cloud Reduction on QoE of Rendered Images}, year = 2020 }

%0 Conference Paper %1 info3-inproceedings-2020-4 %A Seufert, Michael %A Kargl, Julian %A Schauer, Johannes %A Nüchter, Andreas %A Hoßfeld, Tobias %B 12th International Conference on Quality of Multimedia Experience (QoMEX) %C Athlone, Ireland %D 2020 %T Different Points of View: Impact of 3D Point Cloud Reduction on QoE of Rendered Images %X Modern photogrammetric methods as well as laser measurement systems make it easy to collect large 3D point clouds that sample objects or environments. As the recorded point clouds can be used to render computer-generated images and models, they are of particular interest in the domains of geographical and architectural engineering, as well for computer graphics (e.g., games or virtual reality). However, point clouds have a huge storage demand, thus, point clouds shall be reduced by removing some of the points. This will inevitably also reduce the Quality of Experience (QoE) of media, which is rendered from the reduced point clouds. In this work, the impact of two different reduction methods on the QoE of rendered images is investigated from two point of views, i.e., based on ratings from both naive crowdworkers as well as point cloud experts.
Don’t Stop the Music: Crowdsourced QoE Assessment of Music Streaming with Stalling Schwind, Anika; Moldovan, Christian; Janiak, Tim; Dworschak, Nemo-Dario; Hoßfeld, Tobias in 12th International Conference on Quality of Multimedia Experience (QoMEX) (2020).
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Streaming made a lasting effect on the way our society consumes media in the last decade. While due to streaming the way we listen to music and podcasts has changed drastically, there are very few studies about its Quality of Experience (QoE) and possible influence factors. From video QoE studies, we know that, for example, undesirable stops of the stream (stalling events) have a significant impact on QoE. However, the way in which music and video streaming is consumed differs significantly, as music is often played in the background, and thus, the influence of stalling could be significantly different. Thus, this work evaluates the impact of stalling on music streaming QoE. Therefore, we conduct two crowdsourced user studies: In the first study, users have to rate four songs with different stalling patterns and evaluate the degree of impairments. Afterwards, we compare the ratings to the results of a lab study and show that they are highly correlated, and that crowdsourcing is a suitable way of measuring music streaming QoE. In addition, we conduct a second crowdsourcing study to investigate the influence of the user's attentiveness on QoE. Here, participants have to listen to one song with two stalling events, while one half of them had to transcribe a handwritten text with music playing in the background. The attentiveness shows no influence on the perceived streaming quality, but it shows a significant influence on the perceived quality degradation due to stalling events. Furthermore, considerably more stalling events were missed for workers who focused on the transcription. These results are an important step towards establishing new methods for investigating QoE in multimedia.

@inproceedings{info3-inproceedings-2020-7, abstract = {Streaming made a lasting effect on the way our society consumes media in the last decade. While due to streaming the way we listen to music and podcasts has changed drastically, there are very few studies about its Quality of Experience (QoE) and possible influence factors. From video QoE studies, we know that, for example, undesirable stops of the stream (stalling events) have a significant impact on QoE. However, the way in which music and video streaming is consumed differs significantly, as music is often played in the background, and thus, the influence of stalling could be significantly different. Thus, this work evaluates the impact of stalling on music streaming QoE. Therefore, we conduct two crowdsourced user studies: In the first study, users have to rate four songs with different stalling patterns and evaluate the degree of impairments. Afterwards, we compare the ratings to the results of a lab study and show that they are highly correlated, and that crowdsourcing is a suitable way of measuring music streaming QoE. In addition, we conduct a second crowdsourcing study to investigate the influence of the user's attentiveness on QoE. Here, participants have to listen to one song with two stalling events, while one half of them had to transcribe a handwritten text with music playing in the background. The attentiveness shows no influence on the perceived streaming quality, but it shows a significant influence on the perceived quality degradation due to stalling events. Furthermore, considerably more stalling events were missed for workers who focused on the transcription. These results are an important step towards establishing new methods for investigating QoE in multimedia.}, address = {Athlone, Ireland}, author = {Schwind, Anika and Moldovan, Christian and Janiak, Tim and Dworschak, Nemo-Dario and Hoßfeld, Tobias}, booktitle = {12th International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {ua-net}, month = 5, title = {Don’t Stop the Music: Crowdsourced QoE Assessment of Music Streaming with Stalling}, year = 2020 }

%0 Conference Paper %1 info3-inproceedings-2020-7 %A Schwind, Anika %A Moldovan, Christian %A Janiak, Tim %A Dworschak, Nemo-Dario %A Hoßfeld, Tobias %B 12th International Conference on Quality of Multimedia Experience (QoMEX) %C Athlone, Ireland %D 2020 %T Don’t Stop the Music: Crowdsourced QoE Assessment of Music Streaming with Stalling %X Streaming made a lasting effect on the way our society consumes media in the last decade. While due to streaming the way we listen to music and podcasts has changed drastically, there are very few studies about its Quality of Experience (QoE) and possible influence factors. From video QoE studies, we know that, for example, undesirable stops of the stream (stalling events) have a significant impact on QoE. However, the way in which music and video streaming is consumed differs significantly, as music is often played in the background, and thus, the influence of stalling could be significantly different. Thus, this work evaluates the impact of stalling on music streaming QoE. Therefore, we conduct two crowdsourced user studies: In the first study, users have to rate four songs with different stalling patterns and evaluate the degree of impairments. Afterwards, we compare the ratings to the results of a lab study and show that they are highly correlated, and that crowdsourcing is a suitable way of measuring music streaming QoE. In addition, we conduct a second crowdsourcing study to investigate the influence of the user's attentiveness on QoE. Here, participants have to listen to one song with two stalling events, while one half of them had to transcribe a handwritten text with music playing in the background. The attentiveness shows no influence on the perceived streaming quality, but it shows a significant influence on the perceived quality degradation due to stalling events. Furthermore, considerably more stalling events were missed for workers who focused on the transcription. These results are an important step towards establishing new methods for investigating QoE in multimedia.
Are you on Mobile or Desktop? On the Impact of End-User Device on Web QoE Inference from Encrypted Traffic Wassermann, Sarah; Casas, Pedro; Ben Houidi, Zied; Huet, Alexis; Seufert, Michael; Wehner, Nikolas; Schüler, Joshua; Cai, Sheng-Ming; Shi, Hao; Xu, Jinchun; Hoßfeld, Tobias; Rossi, Dario in 16th International Conference on Network and Service Management (CNSM) (2020).
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Web browsing is one of the key applications of the Internet, if not the most important one. We address the problem of Web Quality of Experience (QoE) monitoring from the ISP perspective, relying on in-network, passive measurements. As a proxy to Web QoE, we focus on the analysis of the well-known SpeedIndex (SI) metric. Given the lack of app-level data visibility introduced by the wide adoption of end-to-end encryption, we resort to machine-learning models to infer the SI and the QoE level of individual web page loading sessions, using as input only packet- and flow-level data. Our study targets the impact of different end-user device types (e.g., smartphone, desktop, tablet) on the performance of such models. Empirical evaluations on a large, multi-device, heterogeneous corpus of Web QoE measurements for top popular websites demonstrate that the proposed solution can infer the SI as well as estimate QoE ranges with high accuracy, using either packet-level or flow-level measurements. In addition, we show that the device type adds a strong bias in the feasibility of these Web QoE models, putting into question the applicability of previously conceived approaches on single-device measurements. To improve the state of affairs, we conceive cross-device generalizable models operating at both packet and flow levels, offering a feasible solution for Web QoE monitoring in operational, multi-device networks. To the best of our knowledge, this is the first study tackling the analysis of Web QoE from encrypted network traffic in multi-device scenarios.

@inproceedings{info3-inproceedings-2020-10, abstract = {Web browsing is one of the key applications of the Internet, if not the most important one. We address the problem of Web Quality of Experience (QoE) monitoring from the ISP perspective, relying on in-network, passive measurements. As a proxy to Web QoE, we focus on the analysis of the well-known SpeedIndex (SI) metric. Given the lack of app-level data visibility introduced by the wide adoption of end-to-end encryption, we resort to machine-learning models to infer the SI and the QoE level of individual web page loading sessions, using as input only packet- and flow-level data. Our study targets the impact of different end-user device types (e.g., smartphone, desktop, tablet) on the performance of such models. Empirical evaluations on a large, multi-device, heterogeneous corpus of Web QoE measurements for top popular websites demonstrate that the proposed solution can infer the SI as well as estimate QoE ranges with high accuracy, using either packet-level or flow-level measurements. In addition, we show that the device type adds a strong bias in the feasibility of these Web QoE models, putting into question the applicability of previously conceived approaches on single-device measurements. To improve the state of affairs, we conceive cross-device generalizable models operating at both packet and flow levels, offering a feasible solution for Web QoE monitoring in operational, multi-device networks. To the best of our knowledge, this is the first study tackling the analysis of Web QoE from encrypted network traffic in multi-device scenarios.}, address = {Izmir, Turkey}, author = {Wassermann, Sarah and Casas, Pedro and Ben Houidi, Zied and Huet, Alexis and Seufert, Michael and Wehner, Nikolas and Schüler, Joshua and Cai, Sheng-Ming and Shi, Hao and Xu, Jinchun and Hoßfeld, Tobias and Rossi, Dario}, booktitle = {16th International Conference on Network and Service Management (CNSM)}, keywords = {ucn}, month = 11, title = {Are you on Mobile or Desktop? On the Impact of End-User Device on Web QoE Inference from Encrypted Traffic}, year = 2020 }

%0 Conference Paper %1 info3-inproceedings-2020-10 %A Wassermann, Sarah %A Casas, Pedro %A Ben Houidi, Zied %A Huet, Alexis %A Seufert, Michael %A Wehner, Nikolas %A Schüler, Joshua %A Cai, Sheng-Ming %A Shi, Hao %A Xu, Jinchun %A Hoßfeld, Tobias %A Rossi, Dario %B 16th International Conference on Network and Service Management (CNSM) %C Izmir, Turkey %D 2020 %T Are you on Mobile or Desktop? On the Impact of End-User Device on Web QoE Inference from Encrypted Traffic %X Web browsing is one of the key applications of the Internet, if not the most important one. We address the problem of Web Quality of Experience (QoE) monitoring from the ISP perspective, relying on in-network, passive measurements. As a proxy to Web QoE, we focus on the analysis of the well-known SpeedIndex (SI) metric. Given the lack of app-level data visibility introduced by the wide adoption of end-to-end encryption, we resort to machine-learning models to infer the SI and the QoE level of individual web page loading sessions, using as input only packet- and flow-level data. Our study targets the impact of different end-user device types (e.g., smartphone, desktop, tablet) on the performance of such models. Empirical evaluations on a large, multi-device, heterogeneous corpus of Web QoE measurements for top popular websites demonstrate that the proposed solution can infer the SI as well as estimate QoE ranges with high accuracy, using either packet-level or flow-level measurements. In addition, we show that the device type adds a strong bias in the feasibility of these Web QoE models, putting into question the applicability of previously conceived approaches on single-device measurements. To improve the state of affairs, we conceive cross-device generalizable models operating at both packet and flow levels, offering a feasible solution for Web QoE monitoring in operational, multi-device networks. To the best of our knowledge, this is the first study tackling the analysis of Web QoE from encrypted network traffic in multi-device scenarios.
From QoS Distributions to QoE Distributions: a System’s Perspective Hoßfeld, Tobias; Heegaard, Poul E.; Varela, Martin; Skorin-Kapov, Lea; Fiedler, Markus in 4th International Workshop on Quality of Experience Management (QoE Management 2020), featured by IEEE Conference on Network Softwarization (IEEE NetSoft 2020) (2020).
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In the context of QoE management, network and service providers commonly rely on models that map system QoS conditions (e.g., system response time, packet loss, etc.) to estimated end user QoE values. Observable QoS conditions in the system may be assumed to follow a certain distribution, meaning that different end users will experience different conditions. On the other hand, drawing from the results of subjective user studies, we know that user diversity leads to distributions of user scores for any given test conditions (in this case referring to the QoS parameters of interest). Our previous studies have shown that to correctly derive various QoE metrics (e.g., Mean Opinion Score (MOS), quantiles, probability of users rating 'good or better', etc.) in a system under given conditions, there is a need to consider rating distributions obtained from user studies, which are often times not available. In the paper we extend these findings to show how to approximate user rating distributions given a QoS-to-MOS mapping function and second order statistics. Such a user rating distribution may then be combined with a QoS distribution observed in a system to finally derive corresponding distributions of QoE scores. Scripts are provided for the approximating a QoE distribution with a Beta distribution for given MOS and SOS parameter at https://github.com/hossfeld/approx-qoe-distribution.

@inproceedings{info3-inproceedings-2020-6, abstract = {In the context of QoE management, network and service providers commonly rely on models that map system QoS conditions (e.g., system response time, packet loss, etc.) to estimated end user QoE values. Observable QoS conditions in the system may be assumed to follow a certain distribution, meaning that different end users will experience different conditions. On the other hand, drawing from the results of subjective user studies, we know that user diversity leads to distributions of user scores for any given test conditions (in this case referring to the QoS parameters of interest). Our previous studies have shown that to correctly derive various QoE metrics (e.g., Mean Opinion Score (MOS), quantiles, probability of users rating 'good or better', etc.) in a system under given conditions, there is a need to consider rating distributions obtained from user studies, which are often times not available. In the paper we extend these findings to show how to approximate user rating distributions given a QoS-to-MOS mapping function and second order statistics. Such a user rating distribution may then be combined with a QoS distribution observed in a system to finally derive corresponding distributions of QoE scores. Scripts are provided for the approximating a QoE distribution with a Beta distribution for given MOS and SOS parameter at https://github.com/hossfeld/approx-qoe-distribution.}, address = {Ghent, Belgium}, author = {Hoßfeld, Tobias and Heegaard, Poul E. and Varela, Martin and Skorin-Kapov, Lea and Fiedler, Markus}, booktitle = {4th International Workshop on Quality of Experience Management (QoE Management 2020), featured by IEEE Conference on Network Softwarization (IEEE NetSoft 2020)}, keywords = {sys:hidden:inproceedings}, month = 7, title = {From QoS Distributions to QoE Distributions: a System's Perspective}, year = 2020 }

%0 Conference Paper %1 info3-inproceedings-2020-6 %A Hoßfeld, Tobias %A Heegaard, Poul E. %A Varela, Martin %A Skorin-Kapov, Lea %A Fiedler, Markus %B 4th International Workshop on Quality of Experience Management (QoE Management 2020), featured by IEEE Conference on Network Softwarization (IEEE NetSoft 2020) %C Ghent, Belgium %D 2020 %T From QoS Distributions to QoE Distributions: a System's Perspective %X In the context of QoE management, network and service providers commonly rely on models that map system QoS conditions (e.g., system response time, packet loss, etc.) to estimated end user QoE values. Observable QoS conditions in the system may be assumed to follow a certain distribution, meaning that different end users will experience different conditions. On the other hand, drawing from the results of subjective user studies, we know that user diversity leads to distributions of user scores for any given test conditions (in this case referring to the QoS parameters of interest). Our previous studies have shown that to correctly derive various QoE metrics (e.g., Mean Opinion Score (MOS), quantiles, probability of users rating 'good or better', etc.) in a system under given conditions, there is a need to consider rating distributions obtained from user studies, which are often times not available. In the paper we extend these findings to show how to approximate user rating distributions given a QoS-to-MOS mapping function and second order statistics. Such a user rating distribution may then be combined with a QoS distribution observed in a system to finally derive corresponding distributions of QoE scores. Scripts are provided for the approximating a QoE distribution with a Beta distribution for given MOS and SOS parameter at https://github.com/hossfeld/approx-qoe-distribution.
Bounded Latency with Bridge-Local Stream Reservation and Strict Priority Queuing Grigorjew, Alexej; Metzger, Florian; Hoßfeld, Tobias; Specht, Johannes; Götz, Franz-Josef; Chen, Feng; Schmitt, Jürgen in 11th International Conference on Network of the Future (NoF) (2020).
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Bridge-local latency computation is often regarded with caution, while new shaping mechanisms and timed gates are developed to achieve deterministic guarantees. However, these new concepts require additional hardware support in the forwarding devices, and many of them are based on assumptions of central control and network-wide information being available. This document presents a per-hop latency bound for individual streams in a class-based network that applies the IEEE 802.1Q strict priority transmission selection algorithm. It does not rely on shaping or timed gates and uses the accumulated latency fields during the reservation process to provide upper bounds with bridge-local information. The presented delay bound is proven formally and then evaluated with respect to its accuracy. It shows that deterministic latency with priority queuing is indeed feasible, and it indicates the required information that must be provided during resource reservation, e.g., to protocols developed in IEEE 802.1Qdd.

@inproceedings{info3-inproceedings-2020-17, abstract = {Bridge-local latency computation is often regarded with caution, while new shaping mechanisms and timed gates are developed to achieve deterministic guarantees. However, these new concepts require additional hardware support in the forwarding devices, and many of them are based on assumptions of central control and network-wide information being available. This document presents a per-hop latency bound for individual streams in a class-based network that applies the IEEE 802.1Q strict priority transmission selection algorithm. It does not rely on shaping or timed gates and uses the accumulated latency fields during the reservation process to provide upper bounds with bridge-local information. The presented delay bound is proven formally and then evaluated with respect to its accuracy. It shows that deterministic latency with priority queuing is indeed feasible, and it indicates the required information that must be provided during resource reservation, e.g., to protocols developed in IEEE 802.1Qdd.}, author = {Grigorjew, Alexej and Metzger, Florian and Hoßfeld, Tobias and Specht, Johannes and Götz, Franz-Josef and Chen, Feng and Schmitt, Jürgen}, booktitle = {11th International Conference on Network of the Future (NoF)}, keywords = {ats-performance}, month = 11, title = {Bounded Latency with Bridge-Local Stream Reservation and Strict Priority Queuing}, year = 2020 }

%0 Conference Paper %1 info3-inproceedings-2020-17 %A Grigorjew, Alexej %A Metzger, Florian %A Hoßfeld, Tobias %A Specht, Johannes %A Götz, Franz-Josef %A Chen, Feng %A Schmitt, Jürgen %B 11th International Conference on Network of the Future (NoF) %D 2020 %T Bounded Latency with Bridge-Local Stream Reservation and Strict Priority Queuing %X Bridge-local latency computation is often regarded with caution, while new shaping mechanisms and timed gates are developed to achieve deterministic guarantees. However, these new concepts require additional hardware support in the forwarding devices, and many of them are based on assumptions of central control and network-wide information being available. This document presents a per-hop latency bound for individual streams in a class-based network that applies the IEEE 802.1Q strict priority transmission selection algorithm. It does not rely on shaping or timed gates and uses the accumulated latency fields during the reservation process to provide upper bounds with bridge-local information. The presented delay bound is proven formally and then evaluated with respect to its accuracy. It shows that deterministic latency with priority queuing is indeed feasible, and it indicates the required information that must be provided during resource reservation, e.g., to protocols developed in IEEE 802.1Qdd.
Studying the Impact of the Content Selection Method on the Video QoE on Mobile Devices Wehner, Nikolas; Mertinat, Nils; Seufert, Michael; Hoßfeld, Tobias in 12th International Conference on Quality of Multimedia Experience (QoMEX) (2020).
- [ Abstract ]
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When conducting video QoE studies, participants are usually asked to rate the QoE of prepared test videos. However, participants are given no choice to select content, which they like or in which they are interested. This may cause annoyance or frustration when conducting the QoE study, which eventually might affect the QoE results of the study. The consequent question is whether the content liking has a direct impact on the submitted ratings by the participants and whether the freedom of choosing the video content in QoE studies results in better ratings. To investigate this research question, MCA, an existing framework for crowdsourced video testing, is extended and used in a pilot field study. MCA runs on mobile devices and allows users to watch the tested conditions of a QoE study within video content of their interest. The results of a QoE study with individual and dynamic content selection are compared to a QoE study with pre-selected contents. Moreover, this work includes a comparison to a previous QoE study for validation. As the previous study was conducted on desktop PCs, the MCA study further allows to identify differences in the stalling perception between studies on desktop PCs and mobile devices.

@inproceedings{info3-inproceedings-2020-8, abstract = {When conducting video QoE studies, participants are usually asked to rate the QoE of prepared test videos. However, participants are given no choice to select content, which they like or in which they are interested. This may cause annoyance or frustration when conducting the QoE study, which eventually might affect the QoE results of the study. The consequent question is whether the content liking has a direct impact on the submitted ratings by the participants and whether the freedom of choosing the video content in QoE studies results in better ratings. To investigate this research question, MCA, an existing framework for crowdsourced video testing, is extended and used in a pilot field study. MCA runs on mobile devices and allows users to watch the tested conditions of a QoE study within video content of their interest. The results of a QoE study with individual and dynamic content selection are compared to a QoE study with pre-selected contents. Moreover, this work includes a comparison to a previous QoE study for validation. As the previous study was conducted on desktop PCs, the MCA study further allows to identify differences in the stalling perception between studies on desktop PCs and mobile devices.}, address = {Athlone, Ireland}, author = {Wehner, Nikolas and Mertinat, Nils and Seufert, Michael and Hoßfeld, Tobias}, booktitle = {12th International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {ucn}, month = 5, title = {Studying the Impact of the Content Selection Method on the Video QoE on Mobile Devices}, year = 2020 }

%0 Conference Paper %1 info3-inproceedings-2020-8 %A Wehner, Nikolas %A Mertinat, Nils %A Seufert, Michael %A Hoßfeld, Tobias %B 12th International Conference on Quality of Multimedia Experience (QoMEX) %C Athlone, Ireland %D 2020 %T Studying the Impact of the Content Selection Method on the Video QoE on Mobile Devices %X When conducting video QoE studies, participants are usually asked to rate the QoE of prepared test videos. However, participants are given no choice to select content, which they like or in which they are interested. This may cause annoyance or frustration when conducting the QoE study, which eventually might affect the QoE results of the study. The consequent question is whether the content liking has a direct impact on the submitted ratings by the participants and whether the freedom of choosing the video content in QoE studies results in better ratings. To investigate this research question, MCA, an existing framework for crowdsourced video testing, is extended and used in a pilot field study. MCA runs on mobile devices and allows users to watch the tested conditions of a QoE study within video content of their interest. The results of a QoE study with individual and dynamic content selection are compared to a QoE study with pre-selected contents. Moreover, this work includes a comparison to a previous QoE study for validation. As the previous study was conducted on desktop PCs, the MCA study further allows to identify differences in the stalling perception between studies on desktop PCs and mobile devices.
Poster: Per-Hop Bridge-Local Latency Bounds with Strict Priority Transmission Selection Grigorjew, Alexej; Metzger, Florian; Hoßfeld, Tobias; Specht, Johannes; Götz, Franz-Josef; Chen, Feng; Schmitt, Jürgen in IFIP Networking Conference (2020).
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This work presents a proven per-hop latency bound for real-time networks with admission control that does not rely on shaping or timed gates. It can be applied in a distributed control plane using only bridge-local information, making it an ideal candidate for brownfield real-time network installations. A brief comparison with Asynchronous Traffic Shaping (ATS) shows that the achieved network utilization is comparable to that of ATS in some scenarios, while it only lags behind in scenarios with accumulating bursts where re-shaping could actually reduce the interference of the observed streams.

@inproceedings{info3-inproceedings-2020-16, abstract = {This work presents a proven per-hop latency bound for real-time networks with admission control that does not rely on shaping or timed gates. It can be applied in a distributed control plane using only bridge-local information, making it an ideal candidate for brownfield real-time network installations. A brief comparison with Asynchronous Traffic Shaping (ATS) shows that the achieved network utilization is comparable to that of ATS in some scenarios, while it only lags behind in scenarios with accumulating bursts where re-shaping could actually reduce the interference of the observed streams.}, author = {Grigorjew, Alexej and Metzger, Florian and Hoßfeld, Tobias and Specht, Johannes and Götz, Franz-Josef and Chen, Feng and Schmitt, Jürgen}, booktitle = {IFIP Networking Conference}, keywords = {ats-performance}, month = 6, title = {Poster: Per-Hop Bridge-Local Latency Bounds with Strict Priority Transmission Selection}, year = 2020 }

%0 Conference Paper %1 info3-inproceedings-2020-16 %A Grigorjew, Alexej %A Metzger, Florian %A Hoßfeld, Tobias %A Specht, Johannes %A Götz, Franz-Josef %A Chen, Feng %A Schmitt, Jürgen %B IFIP Networking Conference %D 2020 %T Poster: Per-Hop Bridge-Local Latency Bounds with Strict Priority Transmission Selection %X This work presents a proven per-hop latency bound for real-time networks with admission control that does not rely on shaping or timed gates. It can be applied in a distributed control plane using only bridge-local information, making it an ideal candidate for brownfield real-time network installations. A brief comparison with Asynchronous Traffic Shaping (ATS) shows that the achieved network utilization is comparable to that of ATS in some scenarios, while it only lags behind in scenarios with accumulating bursts where re-shaping could actually reduce the interference of the observed streams.
Optimizing HAS for 360-Degree Videos Moldovan, Christian; Loh, Frank; Seufert, Michael; Hoßfeld, Tobias in 5th IEEE/IFIP International Workshop on Analytics for Network and Service Management (AnNet) (2020).
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@inproceedings{info3-inproceedings-2020-1, address = {Budapest, Hungary}, author = {Moldovan, Christian and Loh, Frank and Seufert, Michael and Hoßfeld, Tobias}, booktitle = {5th IEEE/IFIP International Workshop on Analytics for Network and Service Management (AnNet)}, keywords = {net-man}, month = 4, title = {Optimizing HAS for 360-Degree Videos}, year = 2020 }

%0 Conference Paper %1 info3-inproceedings-2020-1 %A Moldovan, Christian %A Loh, Frank %A Seufert, Michael %A Hoßfeld, Tobias %B 5th IEEE/IFIP International Workshop on Analytics for Network and Service Management (AnNet) %C Budapest, Hungary %D 2020 %T Optimizing HAS for 360-Degree Videos
Is the Uplink Enough? Estimating Video Stalls from Encrypted Network Traffic Loh, Frank; Wamser, Florian; Moldovan, Christian; Zeidler, Bernd; Tsilimantos, Dimitrios; Valentin, Stefan; Hoßfeld, Tobias in 32th IEEE/IFIP Network Operations and Management Symposium (2020).
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Today’s traffic projections speak of almost 58 % video traffic across the Internet. Nearly all video traffic is encrypted, accounting for more than 50 % encrypted traffic worldwide. To analyze video traffic today, or even estimate its quality in the network, a deep look into the traffic characteristics has to be done. But then, important quality metrics from the traffic behavior can be derived. Based on extensive measurements we show in this work how to measure and estimate video stalls for mobile adaptive streaming. The underlying dataset includes more than 900 hours of video footage from the native YouTube app, measured over 18 different videos in 56 network scenarios in two cities in Europe. We outline a possible approach to estimate the video playback buffer size based on uplink video chunk requests in real-time to break down the video stalls. This work is intended as a tool for network operators to receive further knowledge of the characteristics of video streaming traffic to quantify the most important QoE degradation factors of one of the most important applications today.

@inproceedings{info3-inproceedings-2020-2, abstract = {Today’s traffic projections speak of almost 58 % video traffic across the Internet. Nearly all video traffic is encrypted, accounting for more than 50 % encrypted traffic worldwide. To analyze video traffic today, or even estimate its quality in the network, a deep look into the traffic characteristics has to be done. But then, important quality metrics from the traffic behavior can be derived. Based on extensive measurements we show in this work how to measure and estimate video stalls for mobile adaptive streaming. The underlying dataset includes more than 900 hours of video footage from the native YouTube app, measured over 18 different videos in 56 network scenarios in two cities in Europe. We outline a possible approach to estimate the video playback buffer size based on uplink video chunk requests in real-time to break down the video stalls. This work is intended as a tool for network operators to receive further knowledge of the characteristics of video streaming traffic to quantify the most important QoE degradation factors of one of the most important applications today.}, address = {Budapest, Hungary}, author = {Loh, Frank and Wamser, Florian and Moldovan, Christian and Zeidler, Bernd and Tsilimantos, Dimitrios and Valentin, Stefan and Hoßfeld, Tobias}, booktitle = {32th IEEE/IFIP Network Operations and Management Symposium}, keywords = {can}, month = 4, title = {Is the Uplink Enough? Estimating Video Stalls from Encrypted Network Traffic}, year = 2020 }

%0 Conference Paper %1 info3-inproceedings-2020-2 %A Loh, Frank %A Wamser, Florian %A Moldovan, Christian %A Zeidler, Bernd %A Tsilimantos, Dimitrios %A Valentin, Stefan %A Hoßfeld, Tobias %B 32th IEEE/IFIP Network Operations and Management Symposium %C Budapest, Hungary %D 2020 %T Is the Uplink Enough? Estimating Video Stalls from Encrypted Network Traffic %X Today’s traffic projections speak of almost 58 % video traffic across the Internet. Nearly all video traffic is encrypted, accounting for more than 50 % encrypted traffic worldwide. To analyze video traffic today, or even estimate its quality in the network, a deep look into the traffic characteristics has to be done. But then, important quality metrics from the traffic behavior can be derived. Based on extensive measurements we show in this work how to measure and estimate video stalls for mobile adaptive streaming. The underlying dataset includes more than 900 hours of video footage from the native YouTube app, measured over 18 different videos in 56 network scenarios in two cities in Europe. We outline a possible approach to estimate the video playback buffer size based on uplink video chunk requests in real-time to break down the video stalls. This work is intended as a tool for network operators to receive further knowledge of the characteristics of video streaming traffic to quantify the most important QoE degradation factors of one of the most important applications today.
QoE Assessment of Enterprise Applications based on Self-motivated Ratings Borchert, Kathrin; Seufert, Michael; Hildebrand, Kathrin; Hoßfeld, Tobias in 12th International Conference on Quality of Multimedia Experience (QoMEX) (2020).
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- [ BibTeX ]
- [ EndNote ]
In most companies, enterprise applications, such as office products or databases, are heavily used by employees during work hours. Impairments and performance issues not only slow down business processes, but might also increase the frustration of the workforce. While Quality of Experience (QoE) has been widely studied for personal multimedia applications, such as video streaming, its application to the business usage domain is still in its infancy. Due to several reasons, e.g., the high complexity of IT infrastructure, classical QoE studies can hardly be transferred to business applications. These studies are often independent from the context of usage and actively poll ratings from their participants. This work contrasts the commonly used "pull" method for collecting user ratings with a self-motivated "push" approach. This approach is inspired by complaint systems, in which users can directly report problems with a technical system as soon as they notice them. Therefore, performance assessments of a business application from employees of a cooperating company are collected with both rating systems during a time span of 1.5 years. Besides the analysis of the interaction of users with the "push" system, differences between the two methods are discussed. Further, QoE models for the monitored business application are derived based on the self-motivated "push" ratings.

@inproceedings{info3-inproceedings-2020-3, abstract = {In most companies, enterprise applications, such as office products or databases, are heavily used by employees during work hours. Impairments and performance issues not only slow down business processes, but might also increase the frustration of the workforce. While Quality of Experience (QoE) has been widely studied for personal multimedia applications, such as video streaming, its application to the business usage domain is still in its infancy. Due to several reasons, e.g., the high complexity of IT infrastructure, classical QoE studies can hardly be transferred to business applications. These studies are often independent from the context of usage and actively poll ratings from their participants. This work contrasts the commonly used "pull" method for collecting user ratings with a self-motivated "push" approach. This approach is inspired by complaint systems, in which users can directly report problems with a technical system as soon as they notice them. Therefore, performance assessments of a business application from employees of a cooperating company are collected with both rating systems during a time span of 1.5 years. Besides the analysis of the interaction of users with the "push" system, differences between the two methods are discussed. Further, QoE models for the monitored business application are derived based on the self-motivated "push" ratings.}, address = {Athlone, Ireland}, author = {Borchert, Kathrin and Seufert, Michael and Hildebrand, Kathrin and Hoßfeld, Tobias}, booktitle = {12th International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {kubus}, month = 5, title = {QoE Assessment of Enterprise Applications based on Self-motivated Ratings}, year = 2020 }

%0 Conference Paper %1 info3-inproceedings-2020-3 %A Borchert, Kathrin %A Seufert, Michael %A Hildebrand, Kathrin %A Hoßfeld, Tobias %B 12th International Conference on Quality of Multimedia Experience (QoMEX) %C Athlone, Ireland %D 2020 %T QoE Assessment of Enterprise Applications based on Self-motivated Ratings %X In most companies, enterprise applications, such as office products or databases, are heavily used by employees during work hours. Impairments and performance issues not only slow down business processes, but might also increase the frustration of the workforce. While Quality of Experience (QoE) has been widely studied for personal multimedia applications, such as video streaming, its application to the business usage domain is still in its infancy. Due to several reasons, e.g., the high complexity of IT infrastructure, classical QoE studies can hardly be transferred to business applications. These studies are often independent from the context of usage and actively poll ratings from their participants. This work contrasts the commonly used "pull" method for collecting user ratings with a self-motivated "push" approach. This approach is inspired by complaint systems, in which users can directly report problems with a technical system as soon as they notice them. Therefore, performance assessments of a business application from employees of a cooperating company are collected with both rating systems during a time span of 1.5 years. Besides the analysis of the interaction of users with the "push" system, differences between the two methods are discussed. Further, QoE models for the monitored business application are derived based on the self-motivated "push" ratings.
Gray, Nicholas, et al. "Highlighting the Gap Between Expected and Actual Behavior in P4-enabled Networks Gray, Nicholas; Grigorjew, Alexej; Hoßfeld, Tobias; Shukla, Apoorv; Zinner, Thomas in IFIP/IEEE Symposium on Integrated Network and Service Management (IM) (2019).
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