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Wehner, N., Wassermann, S., Casas, P., Seufert, M., Wamser, F.: Beauty is in the Eye of the Smartphone Holder - A Data Driven Analysis of YouTube Mobile QoE. 14th International Conference on Network and Service Management (CNSM). , Rome, Italy (2018).
Measuring the Quality of Experience (QoE) undergone by cellular network users has become paramount for cellular ISPs. Given its overwhelming dominance and ever-growing popularity, this paper focuses on the analysis of QoE for YouTube in mobile networks. Using a large-scale dataset of crowdsourced YouTube QoE measurements collected in smartphones with YoMoApp, we analyze the evolution of multiple relevant QoE-related metrics over time for YouTube mobile users. The dataset includes measurements from more than 360 users worldwide, spanning over the last five years. Our data-driven analysis shows a systematic performance and QoE improvement of YouTube in mobile devices over time, accompanied by an improvement of cellular network performance and by an optimization of the YouTube streaming behavior for smartphones.
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Lugrin, J.-L., Oberdorfer, S., Latoschik, M.E., Wittmann, A., Seufert, C., Grafe, S.: VR-Assisted vs Video-Assisted Teacher Training. Proceedings of the 25th IEEE Virtual Reality (VR) conference (2018).
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Waltemate, T., Gall, D., Roth, D., Botsch, M., Latoschik, M.E.: The Impact of Avatar Personalization and Immersion on Virtual Body Ownership, Presence, and Emotional Response. IEEE Transactions on Visualization and Computer Graphics. 24, 1643-1652 (2018).
This article reports the impact of the degree of personalization and individualization of users' avatars as well as the impact of the degree of immersion on typical psychophysical factors in embodied Virtual Environments. We investigated if and how virtual body ownership (including agency), presence, and emotional response are influenced depending on the specific look of users' avatars, which varied between (1) a generic hand-modeled version, (2) a generic scanned version, and (3) an individualized scanned version. The latter two were created using a state-of-the-art photogrammetry method providing a fast 3D-scan and post-process workflow. Users encountered their avatars in a virtual mirror metaphor using two VR setups that provided a varying degree of immersion, (a) a large screen surround projection (CAVE) and (b) a head-mounted display (HMD). We found several significant as well as a number of notable effects. First, personalized avatars significantly increase body ownership, presence, and dominance compared to their generic counterparts, even if the latter were generated by the same photogrammetry process and hence could be valued as equal in terms of the degree of realism and graphical quality. Second, the degree of immersion significantly increases the body ownership, agency, as well as the feeling of presence. These results substantiate the value of personalized avatars resembling users' real-world appearances as well as the value of the deployed scanning process to generate avatars for VR-setups where the effect strength might be substantial, e.g., in social Virtual Reality (VR) or in medical VR-based therapies relying on embodied interfaces. Additionally, our results also strengthen the value of fully immersive setups which, today, are accessibly for a variety of applications due to the widely available consumer HMDs.
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Horst-Schaper, G., Schaper, P.: [POSTER] Verletzungen mit infektiösem Material Ein Überblick über die Unfallmeldungen bei einem Maximalversorger in den Jahren 2001 bis 2017. 32. Freiburger Symposium Arbeitsmedizin im Gesundheitsdienst (2018).
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Fleszar, K., Mnich, M., Spoerhase, J.: New Algorithms for Maximum Disjoint Paths Based on Tree-Likeness. Mathematical Programming. 171, 433--461 (2018).
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Schaper, P., Grundgeiger, T.: Commission Errors – Determined to do the wrong thing? 5th International Conference on Prospective Memory (2018).
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Hirth, M., Lange, S., Seufert, M., Tran-Gia, P.: Performance Evaluation of Mobile Crowdsensing for Event Detection. Proceedings of the 5th International Workshop on Crowd Assisted Sensing, Pervasive Systems and Communications. , Athens, Greece (2018).
Crowdsensing offers a cost effective way to collect large amounts of sensor data. However, in contrast to fixed sensor deployments, the spatial distribution of the sensors can hardly be influence, as the sensors are carried by participants of the crowdsensing system. This in turn raises the question about the performance of such systems with respect to the detection probability and detection time of spatial events. In order to address this question, we analyze the performance of such a crowdsensing system by means of simulation. We use the traffic infrastructure of a small size city in Germany and simulate the inhabitants’ movement patterns with the well established SUMO mobility generator. Our results show that even if only a small share of inhabitants participates in crowdsensing, events, which have locations that are correlated with the population density, can be easily and quickly detected using such a system. On the contrary, events whose locations are uniformly randomly distributed are much harder to detect using a crowdsensing approach.
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Janiak, L.: Video QoE Measurements in the cloud, (2018).
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Grigorjew, A., Lange, S., Zinner, T., Tran-Gia, P.: Performance Benchmarking of Network Function Chain Placement Algorithms. 19th International GI/ITG Conference on Measurement, Modelling and Evaluation of Computing Systems (MMB) (2018).
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Roth, D., Latoschik, M.E., Bloch, C., Bente, G.: When Some Things are Missing: The Quality of Interpersonal Communication in Social Virtual Reality. (2018).
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Metzger, F., Hoßfeld, T., Skorin-Kapov, L., Liotou, E., Pocta, P., Melvin, H., Siris, V., Zgank, A., Jarschel, M.: Context Monitoring for Improved System Performance and QoE. In: Ganchev, I., van der Mei, R.D., und van den Berg, H. (hrsg.) Autonomous Control for a Reliable Internet of Services: Methods, Models, Approaches, Techniques, Algorithms, and Tools. Springer International Publishing (2018).
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.
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Oberdörfer, S., Fischbach, M., Latoschik, M.E.: Effects of VE Transition Techniques on Presence, IVBO, Efficiency, and Naturalness. Proceedings of the 6th Symposium on Spatial User Interaction. ACM (2018).
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Schwarzmann, S., Zinner, T., Sieber, C., Geissler, S.: Evaluation of the Benefits of Variable Segment Durations for Adaptive Streaming. The 2nd International Workshop on Quality of Experience Management. , Sardinia, Italy (2018).
HTTP Adaptive Streaming (HAS) is the de-facto standard for video delivery over the Internet. It enables the dynamic adaptation of video quality by splitting the video clip into small segments and providing multiple quality levels per segment. Current HAS streaming services typically utilize segments of equal durations. However, this leads to video encoding overhead as segments have to start with I-frames, independently of the encoded video content. In this paper we evaluate the prospects of variable segment durations, where video segments are aligned to the video characteristics. We evaluate the reduction of the encoding overhead and investigate its impact on the stalling probability using a theoretical model. It turns out that the variable approach outperforms the fixed approach in 86% of the evaluated cases with respect to video stalls.
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Lugrin, B., Bartl, A., Striepe, H., Lax, J., Toriizuka, T.: Do I act familiar? Investigating the Similarity-Attraction Principle on Culture-specific Communicative behaviour for Social Robots. Proceedings of the International Conference on Intelligent Robots and Systems. S. 2033-2039. IEEE (2018).
Culture, amongst other individual and social factors, plays a crucial role in human-human interactions. If robots should become a part of our society, they should be able to act in culture-specific manners as well. In this paper, we showcase the implementation of a cultural dichotomy, namely individualism vs. collectivism, in a social robots' conversation. Presenting these conversations to human observers from Germany and Japan, we investigate whether the implemented differences are recognized as such, and whether stereotypical culture-specific behaviours that correspond to the observers' cultural background is preferred. Results suggest that the manipulations in behaviour had the intended effect, but are not reflected in personal preferences.
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Lugrin, J.-L., Ertl, M., Krop, P., Klüpfel, R., Stierstorfer, S., Weisz, B., Rück, M., Schmitt, J., Schmidt, N., Latoschik, M.E.: Any ”Body” There? - Avatar Visibility Effects in a Virtual Reality Game. Proceedings of the 25th IEEE Virtual Reality (VR) conference (2018).
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Nguyen-Ngoc, A., Lange, S., Geissler, S., Zinner, T., Tran-Gia, P.: Estimating the Flow Rule Installation Time of SDN Switches when Facing Control Plane Delay. 19th International GI/ITG Conference on “Measurement, Modelling and Evaluation of Computing Systems”. , Erlangen (2018).
The software defined networking (SDN) paradigm has numerous benefits for network operators, including cost aspects, flexibility, and programmability. In the centralized SDN architecture, the controller can order the installation of flow rules in the switches it manages via FlowMod messages. Since the processing time of these messages has a direct impact on the reaction time of the network, it is a key performance indicator for switches and quantifying it in a reliable manner is required for ensuring state consistency between the control and the data plane. Furthermore, real world deployments not only consist of different data plane hardware, but may feature varying control plane delays. Hence, in this work, we investigate the impact of such a delay on the FlowMod processing time of OpenFlow switches. Firstly, we identify a significant heterogeneity between data plane hardware in terms of processing times as well as the underlying TCP-level behavior. Secondly, we show that despite this heterogeneity, combining switch specific information with delay measurements at the controller can be used to reliably infer FlowMod processing times. We confirm our results with measurements in a dedicated testbed that is comprised of three different hardware switches, three different SDN controllers, and several high precision measurement devices.
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Metzger, F., Heger, R.: Exploring the Transmission Behaviour of Overwatch: The Source of Lag. 30th International Teletraffic Congress (ITC 30) (2018).
This paper explores the full chain of lag contribution factors in a specific online multiplayer game, namely Overwatch: From creating input events over the network and back to displaying the results on the local screen. Together result in the dreaded end-to-end lag. which has a direct impact on the subjective quality one experiences when playing video games. In its investigation, this paper reveals surprising effects in the game's networking behavior that are omitted when colloquially talking about, e.g. a 60 Hz update rate, but must be considered nonetheless. These insights, gained from examining network traces of Overwatch matches that were played on a realistic, resource constrained PC, can then be used to refine end-to-end lag simulation models and reach a better understanding of all responsible components.
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Burger, V., Zinner, T., Dinh-Xuan, L., Wamser, F., Tran-Gia, P.: A Generic Approach to Video Buffer Modeling using Discrete-Time Analysis. ACM Transactions on Multimedia Computing, Communications, and Applications (TOMM). (2018).
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Seufert, M., Zeidler, B., Wamser, F., Karagkioules, T., Tsilimantos, D., Loh, F., Tran-Gia, P., Valentin, S.: A Wrapper for Automatic Measurements with YouTube’s Native Android App. (2018).
YouTube is one of the most popular and demanding services in the Internet today. Thereby, a large portion of this traffic is generated by YouTube’s mobile app. While past studies have shown how to monitor browser-based streaming on desktop PCs (e.g., YoMo) or mobile devices (e.g., YoMoApp), streaming in the native app has not been monitored yet. This paper presents an automated framework for monitoring the streaming in YouTube’s native app for Android. The concept is based on a wrapper application and the Android Debug Bridge (adb), and can be also extended to automatic measurements with other apps. For YouTube, it allows to collect application-layer streaming data, such as current playtime, buffered playtime, video encoding, and quality switches. These data can be complemented with network measurements on the mobile access link to obtain a holistic view on mobile YouTube streaming on Android devices. In addition to describing the software design and testbed setup, this paper discusses an experimental measurement. This study analyzes the streaming in the native YouTube app and compares it to the streaming from the mobile YouTube website via YoMoApp.
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Zimmerer, C., Fischbach, M., Latoschik, M.E.: Space Tentacles - Integrating Multimodal Input into a VR Adventure Game. Proceedings of the 25th IEEE Virtual Reality (VR) conference. IEEE (2018).
Multimodal interfaces for Virtual Reality (VR), e.g., based on speech and gesture input/output (I/O), often exhibit complex system architectures. Tight couplings between the required I/O processing stages and the underlying scene representation and the simulator system’s flow-of-control tend to result in high development and maintainability costs. This paper presents a maintainable solution for realizing such interfaces by means of a cherry-picking approach. A reusable multimodal I/O processing platform is combined with the simulation and rendering capabilities of the Unity game engine, allowing to exploit the game engine’s superior API usability and tool support. The approach is illustrated based on the development of a multimodal VR adventure game called Space Tentacles.
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van Dijk, T.C., Lipp, F., Markfelder, P., Wolff, A.: Computing Storyline Visualizations with Few Block Crossings. In: Frati, F. und Ma, K.-L. (hrsg.) Proc. 25th Int. Sympos. Graph Drawing Network Vis. (GD'17). S. 365--378. Springer-Verlag (2018).
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Byrka, J., Pensyl, T., Rybicki, B., Spoerhase, J., Srinivasan, A., Trinh, K.: An Improved Approximation Algorithm for Knapsack Median Using Sparsification. Algorithmica. 80, 1093--1114 (2018).
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Bloch, C., Roth, D., Vogeley, K.: Seeing It Your Way: Spatial Perspective Taking as a Mechanism for Interpersonal Understanding. Presentation on the 68th Annual Conference of the International Communication Association (ICA), May 24-28, Prague, Czech Republic. (2018).
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Das, A., Fleszar, K., Kobourov, S., Spoerhase, J., Veeramoni, S., Wolff, A.: Approximating the Generalized Minimum Manhattan Network Problem. Algorithmica. 80, 1170--1190 (2018).
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Münster, S., Friedrichs, K., Niebling, F., Seidel-Grzesińska, A. hrsg: Digital Research and Education in Architectural Heritage. Springer International Publishing (2018).
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Hoßfeld, T., Skorin-Kapov, L., Heegaard, P.E., Varela, M.: A new QoE fairness index for QoE management. Quality and User Experience. (2018).
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Lagerspetz, E., Flores, H., Mäkitalo, N., Hui, P., Nurmi, P., Tarkoma, S., Passarella, A., Ott, J., Reichl, P., Conti, M., Fiedler, M., Singh, J., Strufe, T., Hoßfeld, T.: Pervasive Communities in the Internet of People. Proceedings of the 1st International Workshop on Context-Awareness for Multi-Device Pervasive and Mobile Computing (PerCrowd). , Athens, Greece (2018).
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Skorin-Kapov, L., Varela, M., Hoßfeld, T., Chen, K.-T.: A Survey of Emerging Concepts and Challenges for QoE Management of Multimedia Services. ACM Transactions on Multimedia Computing, Communications and Applications. (2018).
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Hoßfeld, T., Metzger, F., Heegaard, P.E.: Traffic Modeling for Aggregated Periodic IoT Data. Proceedings of the 21st Conference on Innovation in Clouds, Internet and Networks (ICIN). , Paris, France (2018).
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Surminski, S., Moldovan, C., Hoßfeld, T.: Practical QoE Evaluation of Adaptive Video Streaming. Proceedings of the 19th International Conference on Measurement, Modelling and Evaluation of Computing Systems (MMB). , Erlangen, Germany (2018).
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Katzmareck, M.: Identifying Relationship Pattern within WhatsApp, (2018).
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Liotou, E., Hoßfeld, T., Moldovan, C., Metzger, F., Tsolkas, D., Passas, N.: The Value of Context-Awareness in Bandwidth-Challenging HTTP Adaptive Streaming Scenarios. In: Ganchev, I., van der Mei, R.D., und van den Berg, H. (hrsg.) Autonomous Control for a Reliable Internet of Services: Methods, Models, Approaches, Techniques, Algorithms, and Tools. Springer International Publishing (2018).
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.
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Niebling, F., Maiwald, F., Barthel, K., Latoschik, M.E.: 4D Augmented City Models, Photogrammetric Creation and Dissemination. In: Münster, S., Friedrichs, K., Niebling, F., und Seidel-Grzesi'nska, A. (hrsg.) Digital Research and Education in Architectural Heritage. S. 196--212. Springer International Publishing, Cham (2018).
The availability of digital image repositories of historical photographs offers new possibilities to historians in their research. In addition to representing a large collection of data records themselves, image archives allow for new methods of research, from large-scale statistical analysis, to algorithmic generation of knowledge, such as historical 3D models, directly from these sources. In this paper, we explore methods to work with digital image libraries, from the creation of 3D or in extension time-annotated 4D models, to the eventual dissemination of research findings in teaching/learning scenarios. We review pedagogical approaches to reach different learning objectives, as well as methods that allow for the inclusion of historic city models employing Augmented Reality in mobile learning environments.
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Yang, J., van der Valk, C., Hoßfeld, T., Redi, J., Bozzon, A.: How do crowdworker communities and microtask markets influenceeach other? A data-driven study on Amazon Mechanical Turk. Université de Fribourg (2018).
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Baumeister, J.: Evaluation of Configuration Knowledge in Industrial Manufacturing. Lernen. Wissen. Daten. Analysen. (LWDA 2018). , Mannheim (2018).
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Borchert, K., Hirth, M., Kummer, M., Laitenberger, U., Slivko, O., Viet, S.: Unemployment and Online Labor, (2018).
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Roth, D., Wienrich, C.: Effects of Media Immersiveness on the Perception of Virtual Characters. In: Dörner, R., Grimm, P., und Geiger, C. (hrsg.) Proceedings of the 15th Workshop on Virtual and Augmented Reality of the GI Special Interest Group VR/AR (2018).
Virtual characters are widely used in digital media and entertainment, and become more frequent in Virtual Reality (VR) applications. Multiple previous works assessed the perception of virtual characters. Yet, a comparison of the effects of non-immersive and immersive settings on character perception and affect recognition has not been presented. Therefore, we conducted a mixed-design study, that assessed the perception of virtual characters in a desktop setting compared to an immersive VR setting. The piloting findings revealed that although typical evaluation dimensions such as humanness or eeriness did not differ significantly, socially related judgments such as sympathy, attractiveness, and trust showed significant differences between the media. We conclude that these dimensions need further assessments, and suggest that pretesting may be done best in the target media.
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Chan, T.M., van Dijk, T.C., Fleszar, K., Spoerhase, J., Wolff, A.: Stabbing Rectangles by Line Segments -- How Decomposition Reduces the Shallow-Cell Complexity. Proc. 29th International Symposium on Algorithms and Computation (ISAAC'18) (2018).
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Niebling, F., Latoschik, M.E.: Browsing Spatial Photography using Augmented Models. Proceedings of the 17th IEEE International Symposium on Mixed and Augmented Reality (ISMAR). IEEE, ACM (2018).
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Roth, D., Mal, D., Purps, C.F., Kullmann, P., Latoschik, M.E.: Injecting Nonverbal Mimicry with Hybrid Avatar-Agent Technologies: A Naïve Approach. Proceedings of the 6th ACM Symposium on Spatial User Interaction (SUI). ACM (2018).
Humans communicate to a large degree through nonverbal behavior. Nonverbal mimicry, i.e., the imitation of another’s behavior can positively affect the social interactions. In virtual environments, user behavior can be replicated to avatars, and agent behaviors can be artificially constructed. By combining both, hybrid avatar-agent technologies aim at actively mediating virtual communication to foster interpersonal understanding and rapport.We present a naïve prototype, the “Mimicry Injector”, that injects artificial mimicry in real-time virtual interactions. In an evaluation study, two participants were embodied in a Virtual Reality (VR) simulation, and had to perform a negotiation task. Their virtual characters either a) replicated only the original behavior or b) displayed the original behavior plus induced mimicry. We found that most participants did not detect the modification. However, the modification did not have a significant impact on the perception of the communication.
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Volodina, E., Aziz, A., Rathgeb, E., Hoßfeld, T.: Application of Visual Analysis to Detect and Analyze Patterns in VoIP Attack Traffic. 17th IEEE International Conference On Trust, Security And Privacy In Computing And Communications/12th IEEE International Conference On Big Data Science And Engineering (TrustCom/BigDataSE) (2018).
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Metter, C., Burger, V., Hu, Z., Pei, K., Wamser, F.: Towards an Active Probing Extension for the ONOS SDN Controller. 2018 28th International Telecommunication Networks and Applications Conference (ITNAC) (ITNAC 2018). S. 8. , Sydney, Australia (2018).
Network monitoring is a complex task and is always a trade-off between granularity of information and the performance impact of the monitoring itself on the network. SDN controllers, such as the ONOS SDN controller make this challenge easier as they can supply centralized information over the whole network. In our previous work we mathematically analyzed the built-in detection mechanism of ONOS and revealed a lack of detection performance and the vulnerability of this process to jitter. These results were also verified by measurements. In this paper we present an Active Probing extension for the ONOS SDN controller that overcomes these shortcomings by emitting probing packets that are transmitted through the network. Statistics over a history of those packets allow for the detection of packet loss. The evaluation by the means of measurements proves the benefits in terms of detection performance and controller load of this application. Furthermore, our extension is able to detect jitter being present in the network and to automatically adapt the probing process to these conditions.
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Bruschke, J., Niebling, F., Wacker, M.: Visualization of Orientations of Spatial Historical Photographs. In: Sablatnig, R. und Wimmer, M. (hrsg.) Eurographics Workshop on Graphics and Cultural Heritage. The Eurographics Association (2018).
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Maiwald, F., Schneider, D., Henze, F., Münster, S., Niebling, F.: FEATURE MATCHING OF HISTORICAL IMAGES BASED ON GEOMETRY OF QUADRILATERALS. International Archives of the Photogrammetry, Remote Sensing & Spatial Information Sciences. 42, (2018).
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Bruschke, J., Niebling, F.: Räumliches Durchsuchen von Repositorien historischer Fotografien. In: Dachselt, R. und Weber, G. (hrsg.) Mensch und Computer 2018 - Workshopband. Gesellschaft für Informatik e.V., Bonn (2018).
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Loh, F.: Quality Change Observation with the YouTube Android App, (2018).
In this work, a detailed observation about the position of quality level changes with the native YouTube android app is done.
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Niebling, F., Bruschke, J., Latoschik, M.E.: Browsing Spatial Photography for Dissemination of Cultural Heritage Research Results using Augmented Models. In: Sablatnig, R. und Wimmer, M. (hrsg.) Eurographics Workshop on Graphics and Cultural Heritage. The Eurographics Association (2018).
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Roth, D., Kullmann, P., Bente, G., Gall, D., Latoschik, M.E.: Effects of Hybrid and Synthetic Social Gaze in Avatar-Mediated Interactions. Proceedings of the 17th IEEE International Symposium on Mixed and Augmented Reality (ISMAR). IEEE, ACM (2018).
Human gaze is a crucial element in social interactions and therefore an important topic for social Augmented, Mixed, and Virtual Reality (AR,MR,VR) applications. In this paper we systematically compare four modes of gaze transmission: (1) natural gaze, (2) hybrid gaze, which combines natural gaze transmission with a social gaze model, (3) synthesized gaze, which combines a random gaze transmission with a social gaze model, and (4) purely random gaze. Investigating dyadic interactions, results show a linear trend for the perception of virtual rapport, trust, and interpersonal attraction, suggesting that these measures increase with higher naturalness and social adequateness of the transmission mode. We further investigated the perception of realism as well as the resulting gaze behavior of the avatars and the human participants. We discuss these results and their implications.
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Roth, D., Mal, D., Polyschev, I., Wiedemann, M., Klöffel, C., Purps, C., To, J., Latoschik, M.E.: Extended Abstract: Artificial Nonverbal Mimicry in Immersive Embodied Social Interactions: Meet the Mimicry Injector. Presentation on the 68th Annual Conference of the International Communication Association (ICA), May 24-28 2018, Prague, Czech Republic. (2018).
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Supervisor: Wamser, F.: Aufbau eines Testbeds zur Demonstration von dynamischen Diensten in der Cloud, (2018).
Cloud Service Placement for Live Video Streaming with a Remote-Controlled Drone florian.wamser@informatik.uni-wuerzburg.de
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Roth, D., Schmitt, J., Bloch, C., Frischlich, L., Latoschik, M.E., Bente, G.: Empathy for Avatars: The Influence of Perceived Authenticity on Empathy and Behavioral Intentions. Presentation on the 68th Annual Conference of the International Communication Association (ICA), May 24-28 2018, Prague, Czech Republic (2018).
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Knapp, T.: Performance Evaluation of DASH Streaming with Real Time Encoding and Continuous Quality Levels, (2018).
Das Thema dieser Arbeit war die Bewertung von DASH Streaming unter Verwendung von Echtzeitkodierung. Zu diesem Zweck wurden vier verschiedene Codecs untersucht. Die spezifischen Parameter der Codecs wurden durch den Effekt klassifiziert, den sie auf die Metriken in Bezug auf die Leistung, die Komprimierung und die Qualität haben. Der Einfluss der signifikanten Parameter auf jede der drei Metriken wurde erforscht. Als Ergebnis wurde die Messung durch eine multi-dimensionale Funktion interpoliert. Nach der Codec Bewertung wurde ein aktuelles Video-Streaming Modell für Echtzeitkodierung erweitert. Folglich wurde ein Auswahlalgorithmus spezifiziert, der durch den Client verwendet wird, um die Kodierungsparameter zu wählen. Durch Anwendung der zuvor bestimmten Codec Funktionen auf das erweiterte Modell können mehrere Szenarien, wie zum Beispiel der Einuss variierender Bandbreite oder die Zeitanforderungsverteilungen mit Fokus auf die Qualitätseigenschaften gegeben durch das Modell, analysiert werden. Die Resultate zeigen die Anpassungsfähigkeit des neuen Modells hin zu veränderter Netzwerkumgebung und bewirken effektiv eine Vermeidung von Videounterbrechungen. Bisher scheint sich die Wahrscheinlichkeitsdichtefunktion des Pufferlevels in Abhängigkeit der Modellparameter in einzelnen Situationen zyklisch zu verändern. Das Modell kann mit jeder der vier untersuchten Codecs kombiniert werden. Den- noch zeigte der Codec H.264 eine geringfügig bessere Ausführung als die Anderen. Unter Verwendung von H.264 als Codec, hat sich das erweiterte Modell gegenüber des Referenzmodells durchgesetzt, da es gute Qualitätswerte unter Komprimierungs- und Performanz-Einschränkungen einhalten konnte. Dies war für das Referenzmodell unmöglich. Diese Arbeit soll Leser dazu ermutigen in Zukunft weitere Untersuchungen in Bezug auf Echtzeitkodierung durchzuführen. Auf technischer Seite können mehr Tests ausgeführt werden, um die Verwendbarkeit des Modells zu überprüfen. Alternativ kann das Modell weiter verbessert und neue Algorithmen erprobt werden.
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Lugrin, B., Eckstein, B., Bergmann, K., Heindl, C.: Adapted Foreigner-directed Communication towards Virtual Agents. International Conference on Intelligent Virtual Agents. Springer (2018).
People tend to adapt to their conversation partners. In mixed-cultural settings, with a native and a non-native speaker, adaptation can manifest itself in the usage of simplified language or increased usage of non-verbal scaffolding to foster understanding. In this contribution, we address the question whether the phenomenon of AFC (adapted, foreigner-directed communication) is also shown towards a virtual agent. We therefore implemented a demonstrator with a local and a foreign agent that interact with human users in a direction giving scenario. A user study revealed that participants behaved differently towards the two agents and adapted both, their verbal and their non-verbal behaviour. We are thus confident, that our demonstrator is well suited to systematically study AFC.
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Eckstein, B., Krapp, E., Lugrin, B.: Towards Serious Games and Applications in Smart Substitutional Reality. 2018 10th International Conference on Virtual Worlds and Games for Serious Applications (VS-Games). S. 25-32 (2018).
Substitutional Reality (SR), the integration of the physical environment into Virtual Reality (VR), is a novel approach to facilitate and intensify the use of home-based VR systems. We propose to extend the passive haptics of SR with the interactive functionality of a smart home environment. This concept of smart SR is meant as a foundation for serious games and applications. In this paper, we describe the concept behind smart SR as well as the prototype in our lab environment. We created multiple virtual environments with a varying degree of mismatch regarding the real world. We present a user study where we examined the influence of these environments on the perceived sense of presence and motivation of users. Our findings showed that presence was high in all conditions while motivation increased with the level of mismatch. This provides us with a promising basis for further research.
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Moldovan, C., Skorin-Kapov, L., Heegaard, P.E., Hoßfeld, T.: Optimal Fairness and Quality in Video Streaming With Multiple Users. 30th International Teletraffic Congress (ITC 30). S. 6. , Vienna, Austria (2018).
With the majority of video distribution services relying on the HTTP adaptive streaming paradigm, a great deal of research is geared towards developing algorithms and solutions for improving user perceived quality while making efficient use of available resources. Our goal is to provide the means for benchmarking such solutions in the context of multiple users accessing Video on Demand content while sharing a bottleneck link. For that purpose, we propose a quadratic problem formulation to compute the theoretical optimum in terms of adaptation strategies and corresponding segment downloads across multiple users under given bandwidth constraints. By aiming to maximize both service quality and fairness, we quantify and compare the impact of different fairness objectives (bandwidth fairness, pattern fairness, and session fairness) on resulting quality and achieved QoE fairness. Based on conducted simulations and parameter studies, our results demonstrate the benefits of optimizing for session fairness as compared to other approaches.
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Weber, K.: Machine Learning for Classification of Streaming Data, (2018).
Laut Vorhersagen [1] soll mobiles Video Streaming im Jahr 2021 etwa dreiviertel des gesamten Internetverkehrs ausmachen. Schon in der heutigen Zeit nimmt es bereits einen großen Teil ein. Dies führt dazu, dass Netzwerkprovider herausfinden müssen, wie sie mit der Masse an Verkehr umgehen sollen, um gleichzeitig ihre Kunden zufrieden stellen zu können. Eine Metrik, um die Nutzerzufriedenheit festzustellen, ist Quality of Experience (QoE). Mit Hilfe von QoE-Management können Provider anhand des Datenverkehrs die Zufriedenheit der Kunden beeinflussen und trotzdem die Kosteneffizienz zu wahren. Ein wichtiger Teil vom QoE-Management ist das QoE-Monitoring. Da allerdings der Netzwerkverkehr verschlüsselt ist und deshalb deep packet inspection nicht mehr verwendet werden kann, muss auf statistische Analysen zurück gegriffen werden. Das Ziel der Arbeit ist es, wichtige QoE-Einflussfaktoren für Mobile Video Stream- ing, speziell am Beispiel YouTube, zu finden mit Hilfe von Machine Learning (ML). Um die Daten zu sammeln, wurde ein Versuchsaufbau bestehend aus einer Linux- Maschine und einem Smartphone benutzt, wobei der PC als Router für das Smartphone zum Internet diente. Auf dem Smartphone lief die originale YouTube-App, welche auch im Google Play Store erhältlich ist, sowie eine Wrapper-App für das Monitoring. Diese kann autonom die YouTube-App starten und Videos abspielen. Während ein Video läuft werden Netzwerk- und Anwendungsinformationen gesam- melt und auf dem Gerät in einer separaten Datei gespeichert. Mit diesen Daten konnten drei verschiedene Datensätze gemessen werden, wobei zwei zur QoE-Vorhersage für initial delay und der dritte Datensatz zur QoE-Vorhersage for stalling events verwendet wurden. Der erste Datensatz bestand aus drei ver- schiedenen Videos und 1070 Instanzen, der zweite Datensatz aus 18 Videos und 1400 Instanzen und der letzte Datensatz aus 930 Instanzen sowie drei Videos. Des Weiteren wurden die Videos mit verschiedenen Bandbreitenbegrenzungen abgespielt, welche von 0.5 Mbits/s bis 5 Mbits/s reichten. Um die Datensätze mit ML klas- sifizieren zu können, mussten die Instanzen zuvor in vordefinierte Klassen anhand ihres initial delay oder ihrer Anzahl an stallings aufgeteilt werden. Versuche mit dem ersten Datensatz zeigten, dass QoE-Schätzungen mit drei Videos nicht aussagekräftig genug sind. Anhand der Ergebnisse mit dem zweiten Datensatz konnten aber folgende wichtige Einflussparameter festgestellt werden: der gesamte Durchsatz von Up- und Downlink, sowie der Durchsatz in den ersten 20 Sekunden. Einflussreiche Parameter sind außerdem der Durchsatz der ersten fünf Segmente, welche nicht leer sind, und deren Größe. Im Anschluss daran wurden weitere QoE-Vorhersagen mit verschiedenen Klassen- aufteilungen gemacht. Es stellte sich heraus, dass die Genauigkeit der Vorhersagen mit steigender Klassenzahl stark nachlässt. Des Weiteren wurden Schätzungen mit Klassenaufteilungen aus anderen QoE-Studien auf unsere Datensätze angewendet, welche allerdings keine weiteren Erkenntnisse lieferten. Zum Schluss wurden QoE-Schätzungen mit dem dritten Datensatz für stalling gemacht und die daraus folgenden Ergebnisse mit den Resultaten der QoE-Vorhersagen mit dem zweiten Datensatz verglichen. Die Faktoren, welche zuvor bei den QoE- Schätzungen für initial delay als wichtige QoE-Einflussfaktoren galten, erwiesen sich bei den QoE-Schätzungen für stalling als nicht einflussreich. Weitere QoE- Vorhersagen zeigten, dass die Anzahl an Qualitätsänderungen während des Videos, sowie die mittlere Ankuftszeit und die kumulative Verteilung der Ankunftszeit der Uplink Requests, großen Einfluss auf die QoE haben.
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Baumeister, J., Reuss, P. hrsg: Proceedings of the Workshop: 'Knowledge and Experience Management' (German SIG meeting, FGWM). (2018).
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Niebling, F., Münster, S., Bruschke, J., Maiwald, F., Friedrichs, K.: Stadtgeschichtliche Forschung anhand räumlich- und zeitlich verorteter Photographien. In: Burghardt, M. und Müller-Birn, C. (hrsg.) INF-DH-2018. Gesellschaft für Informatik e.V., Bonn (2018).
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Scherer, K.P., Rieder, C., Germann, M., Baumeister, J., Plehn, S.: Knowledge-Based Decision Support with Self-Learning Methods. The Twelfth International Conference on Advanced Engineering Computing and Applications in Sciences (ADVCOMP) (2018).
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Korger, A., Baumeister, J.: The SECCO Ontology for the Retrieval and Generation of Security Concepts. ICCBR 2018 - 26th International Conference on Case-Based Reasoning. Springer, Stockholm, Sweden (2018).
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Supervisor: Grigorjew, A.: Consolidation of Resources and Demands in VNF Chain Placement Problems (BA), (2018).
Contact: Alexej Grigorjew <alexej.grigorjew@informatik.uni-wuerzburg.de> Placing Virtual Network Functions in network graphs is an NP-hard problem. Solving large problem instances is often unfeasible due to limited computational resources and time. For many use cases, the problem input is not required in all detail, but can be aggregated into a smaller abstraction. In this work, an algorithm should be implemented that generates such smaller representations of graphs and VNF demands. Further, its performance shall be evaluated by applying (existing) solvers on the results and comparing both runtime and quality of their placements with the original graph.
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Supervisor: Grigorjew, A.: Performance and Parameter Evaluation of P4 Devices (Prakt.), (2018).
Contact: Alexej Grigorjew <alexej.grigorjew@informatik.uni-wuerzburg.de> P4 is a simple programming language for switching devices that allows free configuration of protocols, matching fields, actions, and control flow in compatible hardware and software implementations. This leads to a wide range of different configurations and different realizations of their behavior by different vendors, coupled with tight performance requirements in the data plane. In this work, the influence of various parameters on the performance of P4 implementations shall be measured. In particular, a software implementation and a Netronome P4 hardware NIC shall be compared and evaluated with regard to their program's impact on measures such as throughput and processing delay.
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Hoßfeld, T., Varela, M., Heegaard, P.E., Skorin-Kapov, L.: QoE Analysis of the Setup of Different Internet Services for FIFO Server Systems. Proceedings of the 19th International Conference on Measurement, Modelling and Evaluation of Computing Systems (MMB). , Erlangen, Germany (2018).
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Hoßfeld, T., Metzger, F., Rossi, D.: Speed Index: Relating the Industrial Standard for User Perceived Web Performance to Web QoE. Proceedings of the 10th International Conference on Quality of Multimedia Experience (QoMEX 2018). , Sardinia, Italy (2018).
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Seufert, M., Zeidler, B., Wamser, F., Karagkioules, T., Tsilimantos, D., Loh, F., Tran-Gia, P., Valentin, S.: A Wrapper for Automatic Measurements with YouTube's Native Android App. Network Traffic Measurement and Analysis Conference (TMA). , Wien (2018).
YouTube is one of the most popular and demanding services in the Internet today. Thereby, a large portion of this traffic is generated by YouTube's mobile app. While past studies have shown how to monitor browser-based streaming on desktop PCs (e.g., YoMo) or mobile devices (e.g., YoMoApp), streaming in the native app has not been monitored yet. This paper presents an automated framework for monitoring the streaming in YouTube's native app for Android. The concept is based on a wrapper application and the Android Debug Bridge (adb), and can be also extended to automatic measurements with other apps. For YouTube, it allows to collect application-layer streaming data, such as current playtime, buffered playtime, video encoding, and quality switches. These data can be complemented with network measurements on the mobile access link to obtain a holistic view on mobile YouTube streaming on Android devices. In addition to describing the software design and testbed setup, this paper discusses an experimental measurement. This study analyzes the streaming in the native YouTube app and compares it to the streaming from the mobile YouTube website via YoMoApp.
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Bocerov, M.: Videokompressionsverfahren und ihre Eignung für Adaptives Videostreaming, (2018).
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Byrka, J., Lewandowski, M., Spoerhase, J.: Approximating Node-Weighted k-MST on Planar Graphs. Proc. 16th Workshop on Approximation and Online Algorithms (WAOA'18) (2018).
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Aschenbrenner, D., Rojkov, M., Leutert, F., Verlinden, J., Lukosch, S., Latoschik, M.E., Schilling, K.: Comparing Different Augmented Reality Support Applications for Cooperative Repair of an Industrial Robot. Proceedings of the International Symposium on Mixed and Augmented Reality (ISMAR) (2018).
Digitization and the growing capabilities of data networks enable companies to perform tasks via remote support, which previously required service personnel to travel. But which mixed reality method leads to better results regarding human factors, grounding and per- formance criteria? This paper reports on a collaborative user study, in which a local worker is guided by a remote expert with the help of different augmented reality methods, specifically see-through HMD, spatial projection, and video-mixing tablet. The performed task is an controller exchange in a switch cabinet of an industrial robot, a task rather typical for failure detection within the field. Our study was conducted in collaboration with a technician school of which 50 technician apprentices participated in our study. Our results show clear advantages of using augmented reality (AR) versus traditional conditions (audio, video, screenshot) to enable remote support. It further gives significant indications for using a projection based AR method.
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Schwind, A., Seufert, M.: WhatsAnalyzer: a Tool for Collecting and Analyzing WhatsApp Mobile Messaging Communication Data, (2018).
WhatsAnalyzer is a web-based service, which collects and analyzes chat histories of the mobile messaging application WhatsApp. Thereby, it leverages the e-mail export feature of WhatsApp to obtain the chat histories, which cannot be accessed otherwise due to encrypted storage on the mobile device and end-to-end encrypted transmission over the Internet. Thus, the major asset of the service is that real communication data can be collected without the bias introduced by observing or surveying participants. The collected communication data can be analyzed and provides valuable insights into the communication in WhatsApp and the resulting network traffic. To incentivize users to send chat histories, the privacy of users is respected by anonymizing all communication data. Moreover, some analyses of each chat history can be accessed on a web page by the sender of the chats.
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Sommer, M.: Implementation of a Fuzzing Framework for SDN Security Analysis, (2018).
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Supervisor: Wamser, F.: Implementing a Load Indicator Metric for Network Functions, (2018).
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Gray, N., Lange, S., Zinner, T., Pfaff, B., Hock, D.: Evaluation of a Distributed Control Plane for Managing Heterogeneous SDN-enabled and Legacy Networks. 7th International Conference on Communications and Electronics (ICCE). , Hue, Vietnam (2018).
With the increasing number of devices, protocols and applications, today’s networks are becoming more and more complex. Hence, Software-defined Networking (SDN) tries to ad- dress this issue by separating the data from the control plane and by providing centralized interfaces for network configuration. As legacy devices cannot be replaced instantly due to high costs, both network segments have to be operated in coexistence with defined joints at their edges. To ensure a smooth operation, both controlling instances of these segments are required to exchange information. In this work, we design and implement a data model for storing the information needed to keep the controller and a Network Management System (NMS) synchronized, which are responsible for configuring the SDN-enabled network and the legacy devices respectively. For this, we implement and evaluate a total of three different synchronization strategies by the example of an SDN-based Bring Your Own Device (BYOD) use case. Index Terms—SDN, NMS, Management, Integration, Hetero- geneous Networks, Distributed Control Plane.
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Ziegler, P., Roth, D., Knote, A., Kreuzer, M., von Mammen, S.: Simulator Sick but still Immersed: A Comparison of Head-Object Collision Handling and their Impact on Fun, Immersion, and Simulator Sickness. (2018).
We compared three techniques for handling head-object collisions in room-scale virtual reality (VR). We developed a game whose mechanics induce such collisions which we either addressed (1) not at all, (2) by fading the screen information to black, or (3) by restricting translation, i.e. correcting the virtual offset in such a way that no penetration occurred. We measured these conditions’ impact on simulator sickness, fun, and immersion perception. We found that the translation-restricted method yielded the greatest immersion value but also contributed the most to simulator sickness.
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Loh, F., Wamser, F., Hoßfeld, T., Tran-Gia, P.: Quality of Service Assessment of Live Video Streaming with a Remote-Controlled Drone. IEEE Conference on Network Softwarization. , Montreal, Canada (2018).
Today's networks require a deep understanding of applications to optimize networks, efficiently design networks, and meet traffic demands, application heterogeneity, and application requirements. Current application areas include live video streaming and real-time applications, such as those that are named in 5G use cases with automation, disaster recovery, gaming, and Industry 4.0. In this work, we examine an application scenario with live video streaming and parallel real-time requirements in the uplink for disaster recovery. We study the quality of service (QoS) features of a remote-controlled drone. The drone is controlled via a tablet or smartphone while the video from the camera is transmitted from the drone to the user. There are high demands in both the uplink and downlink direction. The contribution of the work is the measurement of the QoS and application parameters for this scenario and the definition of influencing parameters for the application-layer.
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Schwarzmann, S., Blenk, A., Dobrijevic, O., Jarschel, M., Hotho, A., Zinner, T., Wamser, F.: Big-Data Helps SDN to Improve Application Specific Quality of Service. Big Data and Software Defined Networks. IET (2018).
This chapter first provides an outline of the current results in the domains of: (a) quality-of-service (QoS) / quality-of-experience (QoE) control and management (CaM) for real-time multimedia services that is supported by software-defined networking (SDN), and (b) big data analytics and methods that are used for QoS/QoE CaM. Then, three specific use case scenarios with respect to video streaming services are presented, so as to illustrate the expected benefits of incorporating big data analytics into SDN-based CaM for the purposes of improving or optimizing QoS/QoE. In the end, we describe our vision and a high-level view of an SDN-based architecture for QoS/QoE CaM that is enriched with big data analytics' functional blocks and summarize corresponding challenges.
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Kibanov, M., Becker, M., Müller, J., Atzmueller, M., Hotho, A., Stumme, G.: Adaptive kNN Using Expected Accuracy for Classification of Geo-Spatial Data. Proc. 33rd ACM Symposium On Applied Computing. ACM Press, New York, NY, USA (2018).
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Nogatz, F., Kalkus, J., Seipel, D.: Web-based Visualisation for Definite Clause Grammars using Prolog Meta-Interpreters: System Description. Proceedings of the 20th International Symposium on Principles and Practice of Declarative Programming (2018).
Definite Clause Grammars (DCGs) are a convenient way to describe lists in Prolog. They are a common mean to specify grammars for natural language processing and to parse formal languages. Despite its long history, tools dedicated to the development and debugging of DCGs are rare. In this paper, we present an interactive, web-based tool to visualise the execution of a DCG. To collect the required information from SWI-Prolog, we discuss several techniques, including meta-interpreters, trace interceptors, and term expansions.
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Lange, S., Reinhart, L., Zinner, T., Hock, D., Gray, N., Tran-Gia, P.: Integrating Network Management Information into the SDN Control Plane. IEEE/IFIP Network Operations and Management Symposium (NOMS) (2018).
With software defined networking (SDN), operators benefit from a higher flexibility, cost efficiency, as well as programmability of their networks. Since modern networks are comprised of a multitude of heterogeneous devices and also include non-SDN legacy devices, network management systems (NMSs) are often used in order to monitor and configure the network. Although both, the SDN controller and the NMS, have a centralized view of the network, they operate at different time scales and deal with information at different levels of granularity. In this work, we investigate the impact on the network performance when an NMS regularly provides information to an SDN controller. To this end, we design, implement, and compare three interaction mechanisms based on the ONOS controller. These represent different trade-offs regarding the complexity of the resulting system and its performance. In addition to the default ONOS controller, we develop two extended versions. One performs hash-based load balancing on equal cost paths while the other utilizes external NMS information via ONOS's intent and annotation framework to optimize control plane decisions. In addition to evaluations that show a significant performance improvement when using the optimized controllers, we present a parameter study that highlights the performance impact of network characteristics like the flow interarrival time, the flow duration, and the number of active flows.
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Nogatz, F., Kalkus, J.: Declarative XML Schema Validation with SWI-Prolog. In: Seipel, D., Hanus, M., und Abreu, S. (hrsg.) Declarative Programming and Knowledge Management. S. 187-197 (2018).
XML Schema is a well-established mechanism to define the structure and constrain the content of an XML document. While this approach taken by itself is declarative, currently available tools for XML validation are not. In this paper we introduce an implementation of an XSD validator in SWI-Prolog, made publicly available as the package library(xsd). Our approach is based on flattening the XSD and XML documents into Prolog facts. The top-down validation makes great use of Prolog's backtracking and unification capabilities. To ensure the compliance to the XSD standard and to support the test-driven development, we have created a test framework based on the Test Anything Protocol and SWI-Prolog's quasi-quotations.
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Hefter, J.: Analyzing the Streaming Behaviour of a Popular Video-On-Demand Service, (2018).
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Navarro Bullock, B., Hotho, A., Stumme, G.: Accessing Information with Tags: Search and Ranking. In: Brusilovsky, P. und He, D. (hrsg.) Social Information Access: Systems and Technologies. S. 310--343. Springer International Publishing, Cham (2018).
With the growth of the Social Web, a variety of new web-based services arose and changed the way users interact with the internet and consume information. One central phenomenon was and is tagging which allows to manage, organize and access information in social systems. Tagging helps to manage all kinds of resources, making their access much easier. The first type of social tagging systems were social bookmarking systems, i.e., platforms for storing and sharing bookmarks on the web rather than just in the browser. Meanwhile, (hash-)tagging is central in many other Social Media systems such as social networking sites and micro-blogging platforms. To allow for efficient information access, special algorithms have been developed to guide the user, to search for information and to rank the content based on tagging information contributed by the users.
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Borchert, K., Lange, S., Zinner, T., Hirth, M.: Identification of Delay Thresholds Representing the Perceived Quality of Enterprise Applications. The 2nd International Workshop on Quality of Experience Management. , Sardinia, Italy (2018).
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Fischbach, M., Brandt, M., Zimmerer, C., Lugrin, J.-L., Latoschik, M.E., Lugrin, B.: Follow the White Robot - A Role-Playing Game with a Robot Game Master. Proceedings of the 17th Conference on Autonomous Agents and MultiAgent Systems. ACM, Stockholm, Sweden (2018).
We describe a social robot acting as a game master in an interactive tabletop role-playing game. The Robot Game Master (RGM) takes on the role of different characters, which the human players meet during the adventure, as well as of the narrator. The demonstration presents a novel software and hardware platform that allows the robot to (1) proactively lead through the storyline and to (2) react to changes in the ongoing game in real-time, while (3) fostering players' collaborations.
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Loh, F., Karagkioules, T., Seufert, M., Zeidler, B., Tsilimantos, D., Tran-Gia, P., Valentin, S., Wamser, F.: A Wrapper for Automated Measurements with YouTube’s Native App, (2018).
This demo introduces a wrapper used for automated measurements of mobile video streaming in the Android YouTube app. The difference to traditional measurement techniques is that the measurement is done with the native YouTube app as it is provided in the Google Play Store. In addition to bandwidth or packet loss detection, the QoE of the video stream can be measured and quantified. For this, the amount of quality changes, the current playtime, the buffer level, and statistics like video and audio format are captured. Thus, detailed relationships between network parameters and streaming behavior based on many factors can be detected within the native app available in the Play Store.
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Lugrin, J.-L., Charles, F., Habel, M., Dudaczy, H., Oberdörfer, S., Matthews, J., Porteous, J., Wittmann, A., Seufert, C., Grafe, S., Latoschik, M.E.: Benchmark Framework for Virtual Students’ Behaviours. In: of the 17th International Conference on Autonomous Agents, P. und 2018), M.S. (A.A.M.A.S. (hrsg.) Proceedings of the 17th Conference on Autonomous Agents and MultiAgent Systems. ACM (2018).
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Hettinger, L., Dallmann, A., Zehe, A., Niebler, T., Hotho, A.: ClaiRE at SemEval-2018 Task 7: Classification of Relations using Embeddings. Proceedings of International Workshop on Semantic Evaluation (SemEval-2018). , New Orleans, LA, USA (2018).
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Poignée, F.: Influence of Tension on QoE in Video Streaming, (2018).
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Wollek, A.: Validierung eines generischen HAS-Modells für unterschiedliche Heuristiken., (2018).
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Schwind, A., Wamser, F., Gensler, T., Seufert, M., Casas, P., Tran-Gia, P.: Streaming Characteristics of Spotify Sessions. The 2nd International Workshop on Quality of Experience Management. , Sardinia, Italy (2018).
Internet Service Providers need a thorough understanding of a service to maximize the Quality of Experience (QoE) of their customers by network management. Instead of quantifying the user satisfaction with long and cost-intensive subjective user studies, the QoE can often be estimated with the help of dedicated measurements of application and network parameters. We designed a QoE measurement tool for the popular audio streaming service Spotify that runs inside a Docker software container. The container is able to run headlessly as active measurement probe and emulates a user who is streaming audio files via Spotify. While streaming, network and application parameters are collected that have a high correlation to the user's QoE. The results of the measurements are used to characterize audio streaming in Spotify on application and network layer, and to evaluate important QoE factors.
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Pfeifer, A., Lugrin, B.: Female Robots as Role-models? - the Influence of Robot Gender and Learning Materials on Learning Success. Int. Conf. on Artificial Intelligence in Education (AIED 2018). S. in press (2018).
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Chaplick, S., De, M., Ravsky, A., Spoerhase, J.: Approximation Schemes for Geometric Coverage Problems. Proc. 26th Annual European Symposium on Algorithms (ESA'18). S. 17:1--17:15 (2018).
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Nogatz, F., Frühwirth, T., Seipel, D.: CHR.js: A CHR Implementation in JavaScript. Rules and Reasoning. S. 131-146. Springer (2018).
Constraint Handling Rules (CHR) is usually compiled to logic programming languages. While there are implementations for imperative programming languages such as C and Java, its most popular host language remains Prolog. In this paper, we present CHR.js, a CHR system implemented in JavaScript, that is suitable for both the server-side and interactive client-side web applications. CHR.js provides (i) an interpreter, which is based on the asynchronous execution model of JavaScript, and (ii) an ahead-of-time compiler, resulting in synchronous constraint solvers with better performances. Because of the great popularity of JavaScript, CHR.js is the first CHR system that runs on almost all and even mobile devices, without the need for an additional runtime environment. As an example application we present the CHR.js Playground, an offline-capable web-interface which allows the interactive exploration of CHRs in every modern browser.
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Lugrin, J.-L., Dudaczy, H., Latoschik, M.E.: Low-Frequency Stress Elicitation for VR Training. In: Worlds, 10th I.E.E.E.I.C. on V. und for Serious Applications (VS-Games), (hrsg.) Proceedings of the 10th IEEE International Conference on Virtual Worlds for Serious Applications (VS-Games). IEEE (2018).
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Lugrin, J.-L., Kern, F., Schmidt, R., Kleinbeck, C., Roth, D., Daxer, C., Feigl, T., Mutschler, C., Latoschik, M.E.: A Location-Based VR Museum. In: IEEE, (hrsg.) Proceedings of the 10th IEEE International Conference on Virtual Worlds for Serious Applications (VS-Games). IEEE (2018).
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Supervisor: Loh, F.: Evaluation of the Video Streaming Behavior Using Amazon Echo Show, (2018).
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Nguyen-Ngoc, A., Raffeck, S., Lange, S., Geissler, S., Zinner, T., Tran-Gia, P.: Benchmarking the ONOS Controller with OFCProbe. 7th International Conference on Communications and Electronics (ICCE). , Hue, Vietnam (2018).
The increased popularity of Software Defined Networking (SDN) drives the development and research of all involved components. In particular, state-of-the-art SDN controllers are a central part of the resulting network architecture and have a large impact on the performance of the entire network. Hence, it is necessary to quantify various performance indicators of the SDN controller in order to assess its feasibility in the context of different network characteristics such as topology and network size w.r.t. the number of nodes and links. To this end, we extend the open-source controller benchmarking tool OFCProbe with several novel modules that are capable of recording relevant performance metrics and demonstrate their use in the context of benchmarking the ONOS controller. Furthermore, we investigate the impact of different types of topology characteristics on the performance of the controller. In this work, we focus on several performance indicators for SDN controllers. First, the time that the ONOS controller needs to discover the network topology and update its internal representation of the topology. Second, we investigate the duration of the installation of flow rules that are used for reactive path provisioning. Finally, we measure the response time of the controller when dealing with asynchronous messages.
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Roth, D., Kleinbeck, C., Feigl, T., Mutschler, C., Latoschik, M.E.: Beyond Replication: Augmenting Social Behaviors in Multi-User Virtual Realities. Proceedings of the 25th IEEE Virtual Reality (VR) conference. S. 215-222 (2018).
This paper presents a novel approach for the augmentation of social behaviors in virtual reality (VR). We designed three visual transformations for behavioral phenomena crucial to everyday social interactions: eye contact, joint attention, and grouping. To evaluate the approach, we let users interact socially in a virtual museum using a large-scale multi-user tracking environment. Using a between-subject design (N = 125) we formed groups of five participants. Participants were represented as simplified avatars and experienced the virtual museum simultaneously, either with or without the augmentations. Our results indicate that our approach can significantly increase social presence in multi-user environments and that the augmented experience appears more thought-provoking. Furthermore, the augmentations seem also to affect the actual behavior of participants with regard to more eye contact and more focus on avatars/objects in the scene. We interpret these findings as first indicators for the potential of social augmentations to impact social perception and behavior in VR.
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Seipel, D., Nogatz, F., Abreu, S.: Domain-specific languages in Prolog for declarative expert knowledge in rules and ontologies. Computer Languages, Systems & Structures. 51C, 102-117 (2018).
Declarative if–then rules have proven very useful in many applications of expert systems. They can be managed in deductive databases and evaluated using the well-known forward-chaining approach. For domain-experts, however, the syntax of rules becomes complicated quickly, and already many different knowledge representation formalisms exist. Expert knowledge is often acquired in story form using interviews. In this paper, we discuss its representation by defining domain-specific languages (DSLs) for declarative expert rules. They can be embedded in Prolog systems in internal DSLs using term expansion and as external DSLs using definite clause grammars and quasi-quotations – for more sophisticated syntaxes. Based on the declarative rules and the integration with the Prolog-based deductive database system DDBase, multiple rules acquired in practical case studies can be combined, compared, graphically analysed by domain-experts, and evaluated, resulting in an extensible system for expert knowledge. As a result, the actual modeling DSL becomes executable; the declarative forward-chaining evaluation of deductive databases can be understood by the domain experts. Our DSL for rules can be further improved by integrating ontologies and rule annotations.
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Gall, D., Latoschik, M.E.: The Effect of Haptic Prediction Accuracy on Presence. Proceedings of the 25th IEEE Virtual Reality (VR) conference (2018).
This paper reports on the effect of visually-anchored prediction accuracy of haptic information on the perceived presence of virtual environments. We designed an experiment which explicitly prevented confounding factors potentially introduced by virtual body ownership and/or agency. The experimental design consisted of two main conditions defining congruent vs incongruent visual and haptic cues. Presence was measured during as well as after exposure. A distance estimation task solely based on motor action and the visually-anchored spatial model of the environment was executed to control for perceptual binding. 56 healthy volunteers were randomly assigned to one of two groups in a single-blind mixed-group design study. The study revealed increased presence for high prediction accuracy and decreased presence for low prediction accuracy, while perceptual binding still occurred. The observed effect sizes were in the medium range. The results indicate a significant correlation between prediction accuracy of haptic information and the perceived realness and presence of a virtual environment which gives rise to a discussion about models for dissociative symptom derealisation.
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Gensler, T.: Concept an Implementation of QoE Measurements for Audio Streaming in Spotify, (2018).
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Supervisor: Borchert, K.: Analysis and Correlation of objective and subjective Performance Data of an Enterprise Application, (2018).
Contact: kathrin.borchert@informatik.uni-wuerzburg.de
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Baker, R., Cao, N., Hu, Y., Kaufmann, M., Kobourov, S., Mchedlidze, T., Pupyrev, S., Wolff, A.: Set Visualization Using the Metro Map Metaphor. In: Hu, Y., Micallef, L., Nöllenburg, M., und Rodgers, P. (hrsg.) Scalable Set Visualizations (Dagstuhl Seminar 17332). S. 1--22. Schloss Dagstuhl~-- Leibniz-Zentrum für Informatik (2018).
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Seufert, M., Wehner, N., Casas, P., Wamser, F.: A Fair Share for All: Novel Adaptation Logic for QoE Fairness of HTTP Adaptive Video Streaming. 14th International Conference on Network and Service Management (CNSM). , Rome, Italy (2018).
This paper presents a novel adaptation logic for HTTP adaptive streaming (HAS), which achieves not only a high Quality of Experience (QoE) but also high QoE fairness among independent and heterogeneous clients. The algorithm forces video clients to adapt the requested quality level based on the current network conditions and their individual bit rate requirements, such that the overall quality levels selected by all currently active streaming clients are fairly distributed, i.e., they do not diverge too much. The design of the algorithm is inspired by the well-known Transmission Control Protocol (TCP) congestion control, and drives heterogeneous clients to independently converge on similar quality levels without the need for communicating with each other and/or with a centralized controller in the network. By defining quality levels with equal visual quality, and preparing video representations accordingly, the quality level fairness is extended to QoE fairness. In this work, the design of the algorithm is described and a simulative performance evaluation is conducted to compare the QoE and QoE fairness of the proposed algorithm with other HAS adaptation logics.
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Kryven, M., Ravsky, A., Wolff, A.: Drawing Graphs on Few Circles and Few Spheres. In: Frati, F. und Ma, K.-L. (hrsg.) Proc. 25th Int. Symp. Graph Drawing & Network Vis. (GD'17). Springer-Verlag (2018).
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Gray, N.: Evaluation of Offloading Firewall Rules with P4, (2018).
Contact: nicholas.gray@informatik.uni-wuerzburg.de Firewalls are classical network middle boxes, which are physically implemented within the data path. Following this design pattern causes the network to become inflexible and harder to scale as additional hardware devices have to be deployed whenever the limits of the current configuration are reached, resulting in a high maintenance and requisition cost. Network Function Virtualization (NFV) is a novel paradigm aiming to mitigate these drawbacks by shifting the function of hardware middle boxes to software programs run on Commodity of the Shelf servers. While increasing the network flexibility, it also imposes additional delays on the data path as the complete networking and software stack has to be traversed for each packet. P4 allows the execution and packet matching process on inexpensive, programmable networking cards at line rate. Goal of the thesis is the implementation and evaluation of a distributed stateful firewall based on P4.
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Gray, N.: Evaluation of the Impact of Network Topologies and Applications on Synchronization Strategies of Distributed SDN Controllers, (2018).
Software-defined Networking (SDN) separates the data from the control plane and outsources the latter to a logically centralized instance called the controller. This enables a common view of the network topology and provides a central entity for network configurations. The controller is often distributed to impose no single point of failure and to balance the load efficiently among the physical controller instances. To maintain a consistent view of the network, synchronization between the individual controller instances is required. Controller implementations can be categorized by their utilized synchronization strategy and largely fall in one of two categories, namely horizontal or hierarchical. Goal of this thesis is to evaluate the impact of the network topology and running controller applications on the performance of the controller when using different synchronization mechanisms. As access to large SDN test beds is limited the investigations will be done by simulations within the OMNeT++ framework.
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Supervisor: Grigorjew, A.: Development and Evaluation of Algorithms for Online Distributed Virtual Network Function Deployment and Consolidation (MA), (2018).
Contact: Alexej Grigorjew <alexej.grigorjew@informatik.uni-wuerzburg.de> Network Function Virtualization (NFV) is an emerging trend in the field of network design and operation. Traditionally, various network functions (such as Firewalls, Intrusion Detection Systems, Deep Packet Inspection, ...) are applied to flows in the network, and currently implemented by specialized hardware middleboxes. In the context of NFV, these network functions are now implemented in software and deployed on virtual machines running on commodity servers (→ Virtual Network Functions, VNFs). This enables far greater flexibility and, consequently, comes with new optimization problems. One important part of these problems is to decide how many of these VNF instances are needed, and where they should be placed. Together with various constraints (bandwidth, CPU capacities, ...) and objectives (minimize costs, delays, ...), these questions form an NP-hard optimization problem. In this particular work, the online version of this problem shall be investigated, i.e., new instances are created and removed from the network during its operation, as new traffic demands arrive or leave the network. The aim is to design algorithms that are able to make these decisions locally (i.e., no central decision unit) and to evaluate their performance with respect to chosen objectives, for example by means of a simulation. The student shall (among other things) ... - formalize the problem and its context, - outline its relation to existing, related approaches, - develop optimization algorithms for VNF placement and removal, - define appropriate measures for the quality of attained placements, - evaluate the placement quality by means of these measures (→ discrete event simulation), - and interpret attained results. For further information, feel free to contact us in person or send an email.
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Hamzeheinejad, N., Straka, S., Gall, D., Weilbach, F., Latoschik, M.E.: Immersive Robot-Assisted Virtual Reality Therapy for Neurologically-Caused Gait Impairments. Proceedings of the 25th IEEE Virtual Reality (VR) conference. (2018).
This paper presents an immersive Virtual Reality (VR) therapy system for gait rehabilitation after neurological impairments, e.g., caused by accidents or strokes: The system targets increase of patients' motivation to perform the repeated exercise by providing stimulating virtual exercise environments with the final goal to increase therapy efficiency and effectiveness. Instead of simply working out on immobile stationary devices, the system allows them to walk through and explore a stimulating virtual world. Patients are immersed in the virtual environments using a Head-Mounted Display (HMD). Walking patterns are captured by motion sensors attached to the patients' feet to synchronize locomotion speed between the real and the virtual world. A user-centered design process evaluated usability, user experience, and feasibility to confirm the overall goals of the system before any sensitive clinical trials with impaired patients can start. Overall, the results demonstrated an encouraging user experience and acceptance while it did not induce any unwanted side-effects, e.g., nausea or cyber-sickness.
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Kurak, T.: Einfluss von persönlicher Bekanntheit und Popularität eines Videos auf die QoE, (2018).
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Kryven, M., Ravsky, A., Wolff, A.: Drawing Graphs on Few Circles and Few Spheres. In: Panda, B.S. und Goswami, P.P. (hrsg.) Proc. 4th Conf. Algorithms & Discrete Appl. Math. (CALDAM'18). S. 164--178. Springer-Verlag (2018).
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Baker, R., Cao, N., Hu, Y., Kaufmann, M., Kobourov, S., Mchedlidze, T., Pupyrev, S., Wolff, A.: Set Visualization Using the Metro Map Metaphor. In: Hu, Y., Micallef, L., Nöllenburg, M., und Rodgers, P. (hrsg.) Scalable Set Visualizations (Dagstuhl Seminar 17332). S. 1--22. Schloss Dagstuhl~-- Leibniz-Zentrum für Informatik (2018).
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Nalepa, G.J., Baumeister, J.: Synergies between Knowledge Engineering and Software Engineering. Springer (2018).
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Oberdörfer, S., Latoschik, M.E.: Gamified Knowledge Encoding: Knowledge Training Using Game Mechanics. In: IEEE, (hrsg.) Proceedings of the 10th International Conference on Virtual Worlds and Games for Serious Applications (VS Games 2018). IEEE (2018).
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Supervisor: Geissler, S.: Investigating the Feasibility of Machine Learning for Placement Problems in Softwarized Networks, (2018).
Softwarization is a crucial part of modern and next generation networks, increasing flexibility, scalability and efficiency. However, new challenges regarding the placement of entities like SDN controllers or virtual network functions need to be addressed in order to reap those benefits. Unfortunately, most of these problems are NP-hard and can thus not be solved in an efficient way. In order to alleviate this issue, the goal of this thesis is to investigate the application of machine learning approaches to a special version of a placement problem, namely SDN controller placement. Since this problem can be solved extensively in a reasonably time frame, it is possible to evaluate the machine learning approach to a common ground truth and generate a reasonable amount of training data for the machine learning model.
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Byrka, J., Sornat, K., Spoerhase, J.: Constant-Factor Approximation for Ordered k-Median. Proc. 50th Annual ACM Symposium on the Theory of Computing (STOC'18). S. 620--631 (2018).
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Stauffert, J.-P., Niebling, F., Latoschik, M.E.: Effects of Latency Jitter on Simulator Sickness in a Search Task. 25th IEEE Conference on Virtual Reality and 3D User Interfaces (IEEE VR). S. 121-127 (2018).
Low latency is a fundamental requirement for Virtual Reality (VR) systems to reduce the potential risks of cybersickness and to increase effectiveness, efficiency and user experience. In contrast to the effects of uniform latency degradation, the influence of latency jitter on user experience in VR is not well researched, although today's consumer VR systems are vulnerable in this respect. In this work we report on the impact of latency jitter on cybersickness in HMD-based VR environments. Test subjects are given a search task in Virtual Reality, provoking both head rotation and translation. One group experienced artificially added latency jitter in the tracking data of their head-mounted display. The introduced jitter pattern was a replication of a real-world latency behavior extracted and analyzed from an existing example VR-system. The effects of the introduced latency jitter were measured based on self-reports simulator sickness questionnaire (SSQ) and by taking physiological measurements. We found a significant increase in self-reported simulator sickness. We therefore argue that measure and control of latency based on average values taken at a few time intervals is not enough to assure a required timeliness behavior but that latency jitter needs to be considered when designing experiences for Virtual Reality.
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Kryven, M., Ravsky, A., Wolff, A.: Drawing Graphs on Few Circles and Few Spheres. In: Frati, F. und Ma, K.-L. (hrsg.) Proc. 25th Int. Symp. Graph Drawing & Network Vis. (GD'17). Springer-Verlag (2018).
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Lugrin, B., Bergmann, K., Dippold, J.: Social Robots as a Means of Integration? An Explorative Acceptance Study considering Gender and Non-verbal Behaviour. Proceedings of the International Conference on Intelligent Robots and Systems. S. 2026-2032. IEEE (2018).
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Schatz, R., Schwarzmann, S., Zinner, T., Dobrijevic, O., Liotou, E., Pocta, P., Baraković, S., Baraković Husić, J., Skorin-Kapov, L.: QoE Management for Future Networks. Autonomous Control for a Reliable Internet of Services: Methods, Models, Approaches, Techniques, Algorithms and Tools. Springer (2018).
This chapter discusses prospects of QoE management for future networks and applications. After motivating QoE management, it first provides an introduction to the concept by discussing its origins, key terms and giving an overview of the most relevant existing theoretical frameworks. Then, recent research on promising technical approaches to QoE- driven management that operate across different layers of the networking stack is discussed. Finally, the chapter provides conclusions and an outlook on the future of QoE management with a focus on those key enablers (including cooperation, business models and key technologies) that are essential for ultimately turning QoE-aware network and application management into reality.
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Supervisor: Lange, S.: Simulative Performance Comparison of an SDN Architecture with External Information Sources, (2018).
Software Defined Networking (SDN) marks a paradigm shift towards an externalized and logically centralized network control plane. Due to the open interfaces of the SDN controller, it is possible to take into account different external information such as measurements regarding link delays and bandwidths from sources like Network Management Systems (NMS). This information can arrive at the controller in different levels of granularity (per-flow, per-port, ...) and at different time scales (once per minute, once per second, event-based, ...). The aim of this thesis consists of evaluating the trade-offs between different information exchange mechanisms with respect to performance gains and the overhead that results from exchanging and processing the external information.
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Schwarzmann, S., Blenk, A., Dobrijevic, O., Jarschel, M., Hotho, A., Zinner, T., Wamser, F.: Big-Data Helps SDN to Improve Application Specific Quality of Service. Big Data and Software Defined Networks. IET (2018).
This chapter first provides an outline of the current results in the domains of: (a) quality-of-service (QoS) / quality-of-experience (QoE) control and management (CaM) for real-time multimedia services that is supported by software-defined networking (SDN), and (b) big data analytics and methods that are used for QoS/QoE CaM. Then, three specific use case scenarios with respect to video streaming services are presented, so as to illustrate the expected benefits of incorporating big data analytics into SDN-based CaM for the purposes of improving or optimizing QoS/QoE. In the end, we describe our vision and a high-level view of an SDN-based architecture for QoS/QoE CaM that is enriched with big data analytics' functional blocks and summarize corresponding challenges.
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Casas, P., Seufert, M., Wehner, N., Schwind, A., Wamser, F.: Enhancing Machine Learning based QoE Prediction by Ensemble Models. IEEE ICDCS 3rd Workshop on QoE-based Analysis and Management of Data Communication Networks. , Vienna, Austria (2018).
The number of smartphones connected to wireless networks and the volume of wireless network traffic generated by such devices have dramatically increased in the last few years, making it more challenging to tackle wireless network monitoring applications. The high-dimensionality of network data provided by current smartphone devices opens the door to the massive application of machine learning approaches to improve different wireless networking applications. In this paper we study the specific problem of Quality of Experience (QoE) prediction for popular smartphone apps, using machine learning models and in-smartphone measurements. We evaluate and compare different models for the analysis of smartphone generated data, including single models as well as machine learning ensembles such as bagging, boosting and stacking. Results suggest that, while decision-tree based models are the most accurate single models to predict QoE, ensemble learning models, and in particular stacking ones, are capable to significantly increase accuracy prediction and overall classification performance.
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Dinh-Xuan, L., Seufert, M., Wamser, F., Vassilakis, C., Zafeiropoulos, A., Tran-Gia, P.: Performance Evaluation of Service Functions Chain Placement Algorithms in Edge Cloud. 30th International Teletraffic Congress (ITC30). , Vienna, Austria (2018).
The emergence of Network Function Virtualization (NFV) paradigm has become a potential solution dealing with the rapid growth of the global Internet traffic in the last decades. There, network appliances are transformed into Virtual Network Functions (VNF) running on a standard server. This promises to significantly reduce overall cost and energy consumption. Additionally, hardware-based network function chain is replaced by a chain of the VNFs, called Service Function Chain (SFC). The expected benefit of SFC is the reduction in the complexity when deploying heterogeneous network services. However, the considerable drawback of SFC is the distribution of the VNFs over different hosts. An inefficient placement of VNFs can induce a high latency within the chain and wasted server resources. In this work, we propose four placement algorithms that aim to efficiently place the SFC in servers with regard to minimizing service response time and resource utilization. Herein, heuristic approaches are evaluated against optimal solutions for the placement problems, which are formulated by using Integer Linear Programming. We evaluate and compare these placement strategies in a simulator. Our result shows that the optimized solutions produce lowest service response time and least server utilization in all types of simulated SFCs. On the other hand, the heuristic algorithms are also able to come close to the optimum by simple placing rules.
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Wamser, F., Lombardo, C., Vassilakis, C., Dinh-Xuan, L., Lago, P., Bruschi, R., Tran-Gia, P.: Orchestration and Monitoring in Fog Computing for Personal Edge Cloud Service Support. 2018 IEEE International Symposium on Local and Metropolitan Area Networks (LANMAN) (2018).
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Oberdörfer, S., Latoschik, M.E.: Effectivity of Affine Transformation Knowledge Training Using Game Mechanics. In: IEEE, (hrsg.) Proceedings of the 10th International Conference on Virtual Worlds and Games for Serious Applications (VS Games 2018). IEEE (2018).
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Oberdörfer, S., Latoschik, M.E.: Effective Orbital Mechanics Knowledge Training Using Game Mechanics. In: IEEE, (hrsg.) Proceedings of the 10th International Conference on Virtual Worlds and Games for Serious Applications (VS Games 2018). IEEE (2018).
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Rapp, D., Niebling, F., Latoschik, M.E.: The impact of Pokemon Go and why it’s not about Augmented Reality – Results from a Qualitative Survey. In: Worlds, 10th I.E.E.E.I.C. on V. und for Serious Applications (VS-Games), (hrsg.) Proceedings of the 10th IEEE International Conference on Virtual Worlds for Serious Applications (VS-Games). IEEE (2018).
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Seufert, M., Kamneng Kwam, B., Wamser, F., Tran-Gia, P.: EdgeNetworkCloudSim: Placement of Service Chains in Edge Clouds Using NetworkCloudSim. 1st IEEE International Workshop on Network Programmability - From the Data Center to the Ground (NetFoG). , Bologna, Italy (2017).
Edge cloud computing is a trending paradigm, which extends cloud computing by additionally utilizing computing resources at the network edge, e.g., at mobile base stations. Especially personalized services can be instantiated or migrated close to end users, which improves the latency and supports user mobility. However, the placement of the service chains is crucial for the performance of the services and the energy consumption of the edge cloud platform, and appropriate algorithms have to be designed. To support the simulative performance evaluation of such algorithms, EdgeNetworkCloudSim was developed. It is an extension of NetworkCloudSim, and allows to simulate and evaluate the orchestration and consolidation of service chains in an edge network cloud.
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Lugrin, B., Frommel, J., André, E.: Combining a Data-driven and a Theory-based Approach to Generate Culture-dependent Behaviours for Virtual Characters. In: Faucher, C. (hrsg.) Advances in Culturally-Aware Intelligent Systems and in Cross-Cultural Psychological Studies. Springer (2017).
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Furth, S., Schirm, M., Belli, V., Baumeister, J.: TEKNO: Preparing Legacy Technical Documents for Semantic Information Systems. In: Frasincar, F., Ittoo, A., Nguyen, L.M., und Métais, E. (hrsg.) Natural Language Processing and Information Systems: 22nd International Conference on Applications of Natural Language to Information Systems, NLDB 2017, Liège, Belgium, June 21-23, 2017, Proceedings. S. 429--434. Springer International Publishing, Cham (2017).
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Scherer, K.P., Knöll, D., Baumeister, J., Furth, S.: Knowledge Acquisition by Selflearning Methods with Structured Clinical Data. IJAS: International Conference on Arts and Sciences. , Montreal (2017).
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Lange, S., Grigorjew, A., Zinner, T., Tran-Gia, P., Jarschel, M.: A Multi-Objective Heuristic for the Optimization of Virtual Network Function Chain Placement. 29th International Teletraffic Congress (ITC) (2017).
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Niebling, F.: Spatial Interaction for the Post-Processing of 3D CFD Datasets. In: Kozlikova, B., Schreck, T., und Wischgoll, T. (hrsg.) EuroVis 2017 - Short Papers. The Eurographics Association (2017).
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Seufert, M., Lange, S., Meixner, M.: Automated Decision Making based on Pareto Frontiers in the Context of Service Placement in Networks. 29th International Teletraffic Congress (ITC). , Genoa, Italy (2017).
Virtualization paradigms like cloud computing, software defined networking (SDN), and network functions virtualization (NFV) provide advantages with respect to aspects like flexibility, costs, and scalability. However, management and orchestration of the resulting networks also introduce new challenges. The placement of services, such as virtual machines~(VMs), virtualized network functions~(VNFs), or SDN controllers, is a multi-objective optimization task that confronts operators with a multitude of possible solutions that are incomparable among each other. The goal of this work is to investigate mechanisms that enable automated decision making between such multi-dimensional solutions. To this end, we investigate techniques from the domain of multi-attribute decision making that aggregate the performance of placements to a single numeric score. A comparison between resulting rankings of placements shows that many techniques produce similar results. Hence, placements that achieve good rankings according to many approaches might be viable candidates in the context of automated decision making. In order to illustrate the functionality of the different scoring mechanisms, we perform a case study on a single network graph and a fixed number of objectives and service instances. Additionally, we present aggregated results from broad evaluations on the Internet Topology Zoo and a larger number of objectives as well as varying numbers of service instances. These allow making more reliable statements about the mechanisms' performance and agreement.
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Singer, P., Helic, D., Hotho, A., Strohmaier, M.: A Bayesian Method for Comparing Hypotheses About Human Trails. ACM Trans. Web. 11, 14:1--14:29 (2017).
When users interact with the Web today, they leave sequential digital trails on a massive scale. Examples of such human trails include Web navigation, sequences of online restaurant reviews, or online music play lists. Understanding the factors that drive the production of these trails can be useful, for example, for improving underlying network structures, predicting user clicks, or enhancing recommendations. In this work, we present a method called HypTrails for comparing a set of hypotheses about human trails on the Web, where hypotheses represent beliefs about transitions between states. Our method utilizes Markov chain models with Bayesian inference. The main idea is to incorporate hypotheses as informative Dirichlet priors and to calculate the evidence of the data under them. For eliciting Dirichlet priors from hypotheses, we present an adaption of the so-called (trial) roulette method, and to compare the relative plausibility of hypotheses, we employ Bayes factors. We demonstrate the general mechanics and applicability of HypTrails by performing experiments with (i) synthetic trails for which we control the mechanisms that have produced them and (ii) empirical trails stemming from different domains including Web site navigation, business reviews, and online music played. Our work expands the repertoire of methods available for studying human trails.
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Chaplick, S., Fleszar, K., Lipp, F., Ravsky, A., Verbitsky, O., Wolff, A.: The Complexity of Drawing Graphs on Few Lines and Few Planes. In: Ellen, F., Kolokolova, A., und Sack, J.-R. (hrsg.) Proc. Algorithms Data Struct. Symp. (WADS'17). S. 265--276. Springer-Verlag (2017).
It is well known that any graph admits a crossing-free straight-line drawing in \\($\$\)backslashmathbb R ^3\\($\$\) and that any planar graph admits the same even in \\($\$\)backslashmathbb R ^2\\($\$\) . For a graph G and \\($\$\)d backslashin \backslash\2,3\backslash\\\($\$\) , let \\($\$\)backslashrho ^1\_d(G)\\($\$\) denote the minimum number of lines in \\($\$\)backslashmathbb R ^d\\($\$\) that together can cover all edges of a drawing of G. For \\($\$\)d=2\\($\$\) , G must be planar. We investigate the complexity of computing these parameters and obtain the following hardness and algorithmic results.
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Beutel, A.: Integration of SDN Performance Monitoring in existing Network Management Software, (2017).
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Becker, M., Lemmerich, F., Singer, P., Strohmaier, M., Hotho, A.: MixedTrails: Bayesian hypothesis comparison on heterogeneous sequential data. Data Mining and Knowledge Discovery. (2017).
Sequential traces of user data are frequently observed online and offline, e.g., as sequences of visited websites or as sequences of locations captured by GPS. However, understanding factors explaining the production of sequence data is a challenging task, especially since the data generation is often not homogeneous. For example, navigation behavior might change in different phases of browsing a website or movement behavior may vary between groups of users. In this work, we tackle this task and propose MixedTrails , a Bayesian approach for comparing the plausibility of hypotheses regarding the generative processes of heterogeneous sequence data. Each hypothesis is derived from existing literature, theory, or intuition and represents a belief about transition probabilities between a set of states that can vary between groups of observed transitions. For example, when trying to understand human movement in a city and given some data, a hypothesis assuming tourists to be more likely to move towards points of interests than locals can be shown to be more plausible than a hypothesis assuming the opposite. Our approach incorporates such hypotheses as Bayesian priors in a generative mixed transition Markov chain model, and compares their plausibility utilizing Bayes factors. We discuss analytical and approximate inference methods for calculating the marginal likelihoods for Bayes factors, give guidance on interpreting the results, and illustrate our approach with several experiments on synthetic and empirical data from Wikipedia and Flickr. Thus, this work enables a novel kind of analysis for studying sequential data in many application areas.
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Niebler, T., Hahn, L., Hotho, A.: Learning Word Embeddings from Tagging Data: A methodological comparison. Proceedings of the LWDA (2017).
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Pfaffenberger, F.: Evaluation of Network Monitoring Approaches in Cloud Environments - Experiment and Testbed Design, (2017).
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Hoffmann, M., Jarschel, M., Pries, R., Schneider, P., Jukan, A., Bziuk, W., Gebert, S., Zinner, T., Tran-Gia, P.: SDN and NFV as Enabler for the Distributed Network Cloud. Mobile Networks and Applications. (2017).
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Burger, V.: Performance Evaluation and Optimization of Content Delivery Networks, (2017).
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Tschammler, F.: Relationship between Context and QoE for Video Streaming, (2017).
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Furth, S., Baumeister, J.: Constructing Technical Knowledge Organizations from Document Structures. In: Frasincar, F., Ittoo, A., Nguyen, L.M., und Métais, E. (hrsg.) Natural Language Processing and Information Systems: 22nd International Conference on Applications of Natural Language to Information Systems, NLDB 2017, Liège, Belgium, June 21-23, 2017, Proceedings. S. 210--213. Springer International Publishing, Cham (2017).
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Seufert, M.: Unsupervised QoE Field Study for Mobile YouTube Video Streaming with YoMoApp. , 9th International Conference on Quality of Multimedia Experience (QoMEX), Erfurt, Germany (2017).
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Seufert, M.: Performance Evaluation of Mobile Crowdsensing. , ITG FA 5.2 Workshop on Smart Cities, Lübeck, Germany (2017).
This talk intends to give an overview on Quality of Experience (QoE) monitoring for mobile video streaming, which is an important part of the QoE traffic management cycle. First, the talk recaps the concept of Quality of Experience of HTTP Adaptive Streaming (HAS), which is the current state-of-the-art video streaming technology. Afterwards, different approaches to QoE monitoring are introduced and discussed. Thereby, the talk provides details how the impact of QoE factors, in particular, the quality adaptation of HAS, can be assessed with crowdsourced subjective studies. Moreover, an example is given how to monitor network- and application-layer QoE factors and subjective feedback of end users with a smartphone video streaming app. Finally, the talk wants to stimulate discussions on open research questions of HAS and beyond.
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Ring, M., Wunderlich, S., Grüdl, D., Landes, D., Hotho, A.: Flow-based benchmark data sets for intrusion detection. Proceedings of the 16th European Conference on Cyber Warfare and Security. S. 361--369 (2017).
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Roth, D., Kleinbeck, C., Feigl, T., Mutschler, C., Latoschik, M.E.: [POSTER] Social Augmentations in Multi-User Virtual Reality: A Virtual Museum Experience. IEEE International Symposium on Mixed and Augmented Reality (ISMAR-Adjunct). S. 42-43. IEEE (2017).
This work in progress report demonstrates a novel approach for be- havioral augmentations in Virtual Reality (VR). Using a large scale tracking system, groups of five users explored a virtual museum. We investigated how augmenting social interactions impacts this experience, by designing behavioral transformations for behavio- ral phenomena in social interactions. Preliminary data indicate a reduction of perceived isolation, and a more thought-provoking ex- perience with active behavioral augmentation
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Oberdörfer, S., Heidrich, D., Latoschik, M.E.: Interactive Gamified Virtual Reality Training of Affine Transformation. In: Ullrich, C. und Wessner, M. (hrsg.) Proceedings of DeLFI and GMW Workshops 2017 (2017).
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Fischbach, M.: Enhancing Software Quality of Multimodal Interactive Systems, https://opus.bibliothek.uni-wuerzburg.de/frontdoor/index/index/docId/15272, (2017).
Multimodal interfaces (MMIs) are a promising human-computer interaction paradigm. They are feasible for a wide rang of environments, yet they are especially suited if interactions are spatially and temporally grounded with an environment in which the user is (physically) situated. Real-time interactive systems (RISs) are technical realizations for situated interaction environments, originating from application areas like virtual reality, mixed reality, human-robot interaction, and computer games. RISs include various dedicated processing-, simulation-, and rendering subsystems which collectively maintain a real-time simulation of a coherent application state. They thus fulfil the complex functional requirements of their application areas. Two contradicting principles determine the architecture of RISs: coupling and cohesion. On the one hand, RIS subsystems commonly use specific data structures for multiple purposes to guarantee performance and rely on close semantic and temporal coupling between each other to maintain consistency. This coupling is exacerbated if the integration of artificial intelligence (AI) methods is necessary, such as for realizing MMIs. On the other hand, software qualities like reusability and modifiability call for a decoupling of subsystems and architectural elements with single well-defined purposes, i.e., high cohesion. Systems predominantly favour performance and consistency over reusability and modifiability to handle this contradiction. They thus accept low maintainability in general and hindered scientific progress in the long-term. This thesis presents six semantics-based techniques that extend the established entity-component system (ECS) pattern and pose a solution to this contradiction without sacrificing maintainability: semantic grounding, a semantic entity-component state, grounded actions, semantic queries, code from semantics, and decoupling by semantics. The extension solves the ECS pattern's runtime type deficit, improves component granularity, facilitates access to entity properties outside a subsystem's component association, incorporates a concept to semantically describe behavior as complement to the state representation, and enables compatibility even between RISs. The presented reference implementation Simulator X validates the feasibility of the six techniques and may be (re)used by other researchers due to its availability under an open-source licence. It includes a repertoire of common multimodal input processing steps that showcase the particular adequacy of the six techniques for such processing. The repertoire adds up to the integrated multimodal processing framework miPro, making Simulator X a RIS platform with explicit MMI support. The six semantics-based techniques as well as the reference implementation are validated by four expert reviews, multiple proof of concept prototypes, and two explorative studies. Informal insights gathered throughout the design and development supplement this assessment in the form of lessons learned meant to aid future development in the area.
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Zehe, A., Becker, M., Jannidis, F., Hotho, A.: Towards Sentiment Analysis on German Literature. In: Kern-Isberner, G., Fürnkranz, J., und Thimm, M. (hrsg.) KI 2017: Advances in Artificial Intelligence. S. 387--394. Springer International Publishing, Cham (2017).
Sentiment Analysis is a Natural Language Processing-task that is relevant in a number of contexts, including the analysis of literature. We report on ongoing research towards enabling, for the first time, sentence-level Sentiment Analysis in the domain of German novels. We create a labelled dataset from sentences extracted from German novels and, by adapting existing sentiment classifiers, reach promising F1-scores of 0.67 for binary polarity classification.
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Loh, F., Burger, V., Wamser, F., Tran-Gia, P., Schembra, G., Rametta, C.: Performance Evaluation of Video Streaming Service Chains in Softwarized 5G Networks with Task Graph Reduction. 29th International Teletraffic Congress (ITC) (2017).
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Ring, M., Wunderlich, S., Grüdl, D., Landes, D., Hotho, A.: Creation of Flow-Based Data Sets for Intrusion Detection. Journal of Information Warfare. 16, 41-54 (2017).
Publicly available labelled data sets are necessary for evaluating anomaly-based Intrusion Detection Systems (IDS). However, existing data sets are often not up-to-date or not yet published because of privacy concerns. This paper identifies requirements for good data sets and proposes an approach for their generation. The key idea is to use a test environment and emulate realistic user behaviour with parameterised scripts on the clients. Comprehensive logging mechanisms provide additional information which may be used for a better understanding of the inner dynamics of an IDS. Finally, the proposed approach is used to generate the flow-based CIDDS-002 data set.
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Tscharn, R., Latoschik, M.E., Löffler, D., Hurtienne, J.: "Stop over There" – Natural Gesture and Speech Interaction for Non-Critical Spontaneous Intervention in Autonomous Driving. Proceedings of the 19th ACM International Conference on Multimodal Interaction (ICMI). S. 91-100. ACM (2017).
We propose a novel multimodal intervention strategy for Non-Critical Spontaneous Situations (NCSSs) in autonomous driving. The strategy combines speech and deictic gestures to instruct the car about desired interventions which include spatial references to the current car’s and hence driver’s environment (e.g., “stop over [pointing] there” or “take [pointing] this parking lot”). Speech allows for specifying a large number of maneuvers and functions in the car (e.g., stop, park, etc.), whereas deictic gestures provide a natural way of indicating spatial discourse referents used in these interventions (e.g., near this tree, that parking lot, etc.). Hence, advantages of each modality are exploited. Our multimodal system also supports a semi-immersive Virtual Reality enhanced by Semantic Entities to realize and test the proposed NCSS intervention strategy. The evaluation confirmed our approach to be more natural and intuitive, and also less cognitively demanding com- pared to a combination of speech and touch, a combination that could be seen as a straight-forward alternative to our approach due to already existing and available in-car touch screens.
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Seufert, M.: Unperturbed Video Streaming QoE Under Web Page Related Context Factors. , 9th International Conference on Quality of Multimedia Experience (QoMEX), Erfurt, Germany (2017).
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Latoschik, M.E., Weilbach, F., Hamzeheinejad, N., Gall, D.: VRGait: An Immersive Virtual Reality System for Gait-Specific Neurorehabilitation and Therapy. European Congress of NeuroRehabilitation 2017: ECNR2017. , Lausanne (2017).
Fortunately, physiotherapy and repetitive movement during exercises allows to regain motor functions lost by neurological injuries, i.e., caused by strokes. Exercising is exhausting and patients’ motivation plays a central role in the effectiveness or such therapies. Unfortunately, dedicated therapy equipment often requires to restrict users or to be setup in lesser attractive environments due to, e.g., building statics. In addition, such systems currently do not exploit the potential of adaptive training stimuli based on movement mimicry. We introduce first results of a VR based gait rehabilitation system: VRGait immerses patients into alternative virtual environments and maps their movements on the therapy device to movements in the virtual worlds (see Figure 1). VRGait’s goals are to strengthen therapy effectiveness (1) by increased motivation from inspiring walking escapes (think beach or mountain scenes) and gamified tasks and (2) by exploiting motor mimicry caused by their controlled virtual avatars or counterparts walking together with them.
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Sperlich, B., Becker, M., Hotho, A., Wallmann-Sperlich, B., Sareban, M., Winkert, K., Steinacker, J.M., Treff, G.: Sedentary Behavior among National Elite Rowers during Off-Training—A Pilot Study. Frontiers in Physiology. 8, 655 (2017).
The aim of this pilot study was to analyze the off-training physical activity (PA) profile in national elite German U23 rowers during 31 days of their preparation period. The hours spent in each PA category (i.e. sedentary: <1.5 MET; light physical activity: 1.5–3 MET; moderate physical activity: 3–6 MET and vigorous intense physical activity: >6 MET) were calculated for every valid day (i.e. > 480 min of wear time). The off-training PA during 21 weekdays and 10 weekend days of the final 11-wk preparation period was assessed by a wrist-worn multisensory device (Microsoft Band II (MSBII)). A total of 11 rowers provided valid data (i.e. > 480 min/day) for 11.6 week days and 4.8 weekend days during the 31 days observation period. The average sedentary time was 11.63±1.25 hours per day during the week and 12.49±1.10 hours per day on the weekend, with a tendency to be higher on the weekend compared to weekdays (p = 0.06; d = 0.73). The average time in light, moderate and vigorous PA during the weekdays was 1.27±1.15, 0.76±0.37, 0.51±0.44 hours per day and 0.67±0.43, 0.59±0.37, 0.53±0.32 hours per weekend day. Light physical activity was higher during weekdays compared to the weekend (p = 0.04; d = 0.69) Based on our pilot study of eleven national elite rowers we conclude that rowers display a considerable sedentary off-training behavior of more than 11.5 hours/day.
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Striepe, H., Lugrin, B.: There Once Was a Robot Storyteller: Measuring the Effects of Emotion and Non-verbal Behaviour. 9th Int. Conf. on Social Robotics (ICSR 2017). Springer International Publishing (2017).
Social Robots bear great potential to tell stories to human listeners. Through their embodiment and ability to display non-verbal and emotional behaviour, additional modalities can be used to transport the user into the story compared to traditional media such as books or audio books. Based on theoretical knowledge about the design of social robot storytellers and the analysis of human storytellers, we designed the behaviour of an emotional social robot storyteller and compared it to a neutral version of the robotic storyteller and the voice of a human story- teller represented by an audio book. Results suggest that the emotional robot is able to transport the participants equally well as the traditional audio book, while the neutral robot performed worse. We therefore claim, that emotional behaviour in the domain of robotic storytelling should be carefully designed to support the story rather then preventing a good transportation.
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Tüchert, A.: Influence of loading delays on the perceived quality of web-based enterprise portals, (2017).
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Stulier, N.: Evaluation of Cranial Deformations Using Crowdsourcing, (2017).
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Allendorf, F.: Assessing the Impact of Network Impairments on the Performance of Players in DOTA 2, (2017).
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Ring, M., Landes, D., Dallmann, A., Hotho, A.: IP2Vec: Learning Similarities Between IP Addresses. 2017 IEEE International Conference on Data Mining Workshops (ICDMW). 657-666 (2017).
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Borchert, K., Hirth, M., Schnitzer, S., Rensing, C.: Impact of Task Recommendation Systems in Crowdsourcing Platforms. Workshop on Responsible Recommendation at RecSys 2017. , Como, Italy (2017).
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Ring, M., Wunderlich, S., Grüdl, D., Landes, D., Hotho, A.: A Toolset for Intrusion and Insider Threat Detection. In: Palomares Carrascosa, I., Kalutarage, H.K., und Huang, Y. (hrsg.) Data Analytics and Decision Support for Cybersecurity: Trends, Methodologies and Applications. S. 3--31. Springer International Publishing, Cham (2017).
Company data are a valuable asset and must be protected against unauthorized access and manipulation. In this contribution, we report on our ongoing work that aims to support IT security experts with identifying novel or obfuscated attacks in company networks, irrespective of their origin inside or outside the company network. A new toolset for anomaly based network intrusion detection is proposed. This toolset uses flow-based data which can be easily retrieved by central network components. We study the challenges of analysing flow-based data streams using data mining algorithms and build an appropriate approach step by step. In contrast to previous work, we collect flow-based data for each host over a certain time window, include the knowledge of domain experts and analyse the data from three different views. We argue that incorporating expert knowledge and previous flows allow us to create more meaningful attributes for subsequent analysis methods. This way, we try to detect novel attacks while simultaneously limiting the number of false positives.
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Barbic, J., D'Cruz, M., Latoschik, M.E., Slater, M., Bourdot, P. hrsg: Virtual Reality and Augmented Reality, Proceedings of the 14th EuroVR International Conference, EuroVR 2017. Springer (2017).
This book constitutes the refereed proceedings of the 14th International Conference on Virtual Reality and Augmented Reality, EuroVR 2017, held in Laval, France, in December 2017. The 10 full papers and 2 short papers presented were carefully reviewed and selected from 36 submissions. The papers are organized in four topical sections: interaction models and user studies, visual and haptic real-time rendering, perception and cognition, and rehabilitation and safety.
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Schaper, P., Grundgeiger, T.: Commission errors in delay-execute prospective memory tasks. Quarterly Journal of Experimental Psychology. 70, 1423--1438 (2017).
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Stauffert, J.-P., Niebling, F., Latoschik, M.E.: A Latency and Latency Jitter Simulation Framework with OSVR. 10th Workshop on Software Engineering and Architectures for Realtime Interactive Systems (SEARIS), IEEE Computer Society, (2017) (2017).
Latency is a pressing problem in Virtual Reality (VR) applications. Low latencies are required for VR to reduce perceptual artifacts and cyber sickness. Latency jitter, i.e. variance in the pattern of latency, prevent coping mechanisms as users can't adapt. Low latency is a fundamental timeliness requirement to reduce the potential risks of cyber sickness and to increase effectiveness, efficiency, and user experience of Virtual Reality Systems. The effects of uniform latency degradation based on mean or worst-case values are well researched. In contrast, the effects of latency jitter, the distribution pattern of latency changes over time has largely been ignored so far, although today's consumer VR systems are extremely vulnerable in this respect. In this paper, we propose to create a model of latency and latency jitter with empirical distributions as well as a method of using those models to inject latency. The process of creating a latency model is demonstrated with an example of gathering and converting latency samples from an example application. We show how to simulate latency and motivate to use it in middleware to allow for less intrusive latency effect evaluations.
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Haunert, J.-H., Wolff, A.: Beyond Maximum Independent Set: An Extended Integer Programming Formulation for Point Labeling. International Journal of Geo-Information. 6, article 342, 20 pages (2017).
Map labeling is a classical problem of cartography that has frequently been approached by combinatorial optimization. Given a set of features in a map and for each feature a set of label candidates, a common problem is to select an independent set of labels (that is, a labeling without label--label intersections) that contains as many labels as possible and at most one label for each feature. To obtain solutions of high cartographic quality, the labels can be weighted and one can maximize the total weight (rather than the number) of the selected labels. We argue, however, that when maximizing the weight of the labeling, the influences of labels on other labels are insufficiently addressed. Furthermore, in a maximum-weight labeling, the labels tend to be densely packed and thus the map background can be occluded too much. We propose extensions of an existing model to overcome these limitations. Since even without our extensions the problem is NP-hard, we cannot hope for an efficient exact algorithm for the problem. Therefore, we present a formalization of our model as an integer linear program (ILP). This allows us to compute optimal solutions in reasonable time, which we demonstrate both for randomly generated point sets and an existing data set of cities. Moreover, a relaxation of our ILP allows for a simple and efficient heuristic, which yielded near-optimal solutions for our instances.
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Kamneng Kwam, B.: Static Placement of Services on Edge Servers, (2017).
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Lorenz, C., Hock, D., Scherer, J., Durner, R., Kellerer, W., Gebert, S., Gray, N., Zinner, T., Tran-Gia, P.: An SDN/NFV-enabled Enterprise Network Architecture Offering Fine-Grained Security Policy Enforcement. IEEE Communications Magazine. 55, 217 - 223 (2017).
In recent years, the number of attacks and threat vectors against enterprise networks have been constantly increasing in numbers and variety. In addition, new challenges arise not only to the level of provided security, but also to the scalability and manageability of the deployed countermeasures such as firewalls and intrusion detection systems. Despite these attacks, the main security systems, e.g., network firewalls, have remained rather unchanged. Due to the tight integration into the physical network’s infrastructure, a dynamic resource allocation to adapt the security measures to the current network conditions is a difficult undertaking. Therefore, in this work, we analyze and compare different architectural design patterns for the integration of SDN/NFV-based security solutions into enterprise networks.
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Burger, V., Seufert, M., Zinner, T., Tran-Gia, P.: An Approximation of the Backhaul Bandwidth Aggregation Potential Using a Partial Sharing Scheme. 15th IFIP/IEEE International Symposium on Integrated Network Management (IM). , Lisbon, Portugal (2017).
To cope with the increasing demands of mobile devices and the limited capacity of cellular networks, mobile connections are offloaded to WiFi. The access capacity is further increased by aggregating backhaul bandwidth of WiFi access links. To analyze the performance of aggregated access links we develop a model for two and more cooperating systems sharing capacities using an offloading scheme. The state probabilities of the different cooperating systems in the analytic model are determined by a fixed point iterative procedure. By investigating an inner and outer composite system we are able to analyze the system in imbalanced load conditions where the system reaches its full potential utilizing spare bandwidth. To evaluate the robustness of the system against users that try to exploit the system, the bandwidth received by prioritized users is quantified.
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van Dijk, T.C., Fink, M., Fischer, N., Lipp, F., Markfelder, P., Ravsky, A., Suri, S., Wolff, A.: Block Crossings in Storyline Visualizations. Journal of Graph Algorithms & Applications. 21, 873--913 (2017).
Storyline visualizations help visualize encounters of the characters in a story over time. Each character is represented by an x-monotone curve that goes from left to right visualizing progression of time. A meeting is represented by having the characters that participate in the meeting run close together for some time. In order to keep the visual complexity low, rather than just minimizing pairwise crossings of curves, we propose to count block crossings, that is, pairs of intersecting bundles of lines. In a block crossing, two blocks of parallel lines intersect each other, which is less distracting than the same number of individual crossings being spread over the drawing. In this paper, we show that minimizing the number of block crossings is NP-hard, even if all meetings are of size 2. For this special case, we present a greedy heuristic, which we evaluate experimentally. We show that the general case is fixed-parameter tractable. Our main results is a constant-factor approximation algorithm for meetings of bounded size. The algorithm is based on (approximately) solving a hyperedge deletion problem on hypergraphs that may be of independent interest.
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Schaper, P., Grundgeiger, T.: The effect of different distractions on remembering delayed intentions. Memory. 26, 154-170 (2017).
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Roth, D., Latoschik, M.E., Bente, G.: Hello from the Other Side Behavioral Realism and Social Augmentation in Shared Virtual Environments. Presentation at the 3rd Virtual Social Interaction Workshop, Bielefeld University, Bielefeld (2017).
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Surminski, S., Moldovan, C., Hoßfeld, T.: Saving Bandwidth by Limiting the Buffer Size in HTTP Adaptive Streaming. MMBnet 2017 Proceedings of the 9th GI/ITG Workshop. , Hamburg, Germany (2017).
Video streaming is one of the most bandwidth-intensive applications on the Internet. In HTTP adaptive video streaming the video quality is selected according to the available bandwidth. To compensate bandwidth fluctuations, players use a buffer in order to ensure a smooth video output. On one hand, if the buffer runs empty, the video playback stops, which users experience as negative. On the other hand, if the user aborts video playback, the video in the buffer was unnecessarily transmitted, hence this bandwidth was wasted. In this paper, we present a study in which we investigate the behavior of two video players and different buffer configurations in real-world bandwidth scenarios. Thereby, we focus on the dimensioning of the buffer size and the tradeoff between wasted bandwidth and the playback quality
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Moldovan, C., Hagn, K., Sieber, C., Kellerer, W., Hoßfeld, T.: Keep Calm and Don’t Switch: About the Relationship Between Switches and Quality in HAS. 29th International Teletraffic Congress (ITC 29). S. 6. , Genoa, Italy (2017).
Video streaming has established itself as the main method to consume multimedia content on the Internet. The most widespread technique is HTTP Adaptive Streaming which is used by large video service platforms such as YouTube and Netflix. In order to guarantee a high QoE, different adaptation strategies have been developed that lead to different video playout patterns. While some strategies may be more aggressive than others and often adapt the video quality, it is not clear which strategy is the best. In this paper, we want to identify the trade-off between the av- erage video quality and switches in the quality during playout. We do this with a user-centric view and try to optimize the adaptation depending on the user preference with a quadratic program. This work allows us to put existing and future video adaptation algorithms in perspective with respect to user preferences. Our results show that the video quality can already be increased greatly by allowing few switches while more switches lead to diminishing gains. This is a novel discovery that is important for user-centric QoE-management which is of high interest for ISPs and video service providers.
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Popp, C.: Study on the Accuracy of Video Monitoring VNF in High Mobility Environments, (2017).
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Fischbach, M., Wiebusch, D., Latoschik, M.E.: Semantic Entity-Component State Management Techniques to Enhance Software Quality for Multimodal VR-Systems. IEEE Transactions on Visualization and Computer Graphics. 23, 1342-1351 (2017).
Modularity, modifiability, reusability, and API usability are important qualities that determine the maintainability of complex software architectures typical for Virtual, Augmented, and Mixed Reality (VR, AR, MR) applications. These architectures address various input-, output-, and processing aspects, which are usually implemented by dedicated software modules. Collectively, these modules have to maintain the real-time simulation of a coherent application state. This requirement, however, implicates multiple semantic as well as temporal state representation- and access interdependencies between modules, exacerbating maintainable solutions. This paper presents five semantics-based software techniques for state management that extend the well-established entity-component system (ECS) pattern, foster modularity and enhance overall maintainability. A walk-through of typical implementation aspects of multimodal (speech and gesture) interfaces is used to highlight the techniques' benefits, providing a typical example for demanding software architectures in VR, AR and MR. Finally, central implementation details are compared against prominent alternatives.
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Schwind, A.: Concept and Implementation of QoE Measurements in a Mobile Broadband Testbed, (2017).
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Meixner, M.: Methods for Assessment of Multi-objective Optimization Algorithms with Application in the Context of SDN, (2017).
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Flaig, N.: Simulative Performance Comparison of Adaptation Logics for HTTP Adaptive Streaming, (2017).
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Iffländer, L., Wamser, F., Metter, C., Tran-Gia, P., Kounev, S.: Performance Assessment of Cloud Migrations from Network and Application Point of View. Proceedings of 9th EAI International Conference on Mobile Networks and Management (MONAMI 2017). , Melbourne, Australia (2017).
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Lammers, S., Geiger, A., Roth, D., Sevdalis, V., Bente, G., Vogeley, K.: Understanding "What" or Understanding "How": Mirroring or Mentalizing Other Person's Actions. A New Approach to Neuroimaging of the Social Brain. Poster presented at the 2. Scientific Symposium of the B.Sc./M.Sc. Neuroscience, University of Cologne, Germany (2017).
The mirror neuron system (MNS) and the mentalizing system (MENT) are both important in social interaction [1]. Previous studies in the field of social cognitive neuroscience mainly investigated MNS and MENT separately [2]. The stimuli used in these studies were always substantially different (videos of human motion for MNS vs. verbal or written stories for MENT). To provide the systematic study of both systems we designed video-stimuli, which (together with two specific forced-choice questions) differentially activate both systems. The usage of virtual characters for the investigation of nonverbal behavior has been proven to be eco- logically valid [3]. Our design will allow to discriminate more precisely between the two systems and help get a better understanding of the underlying neural basis. Furthermore it may provide new insights into the neurobiology of psychopathological conditions including autism spectrum disorder (ASD).
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Seufert, M.: Concept and Implementation of Video QoE Measurements in a Mobile Broadband Testbed. , IEEE/IFIP Workshop on Mobile Network Measurement (MNM’17), Dublin, Ireland (2017).
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Schaper, P., Grundgeiger, T.: I should have stopped – Investigating the role of response suppression in commission errors. Beiträge zur 59.Tagung experimentell arbeitender Psychologen (2017).
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van Dijk, T.C., Fink, M., Fischer, N., Lipp, F., Markfelder, P., Ravsky, A., Suri, S., Wolff, A.: Block Crossings in Storyline Visualizations. Journal of Graph Algorithms & Applications. 21, 873--913 (2017).
Storyline visualizations help visualize encounters of the characters in a story over time. Each character is represented by an x-monotone curve that goes from left to right visualizing progression of time. A meeting is represented by having the characters that participate in the meeting run close together for some time. In order to keep the visual complexity low, rather than just minimizing pairwise crossings of curves, we propose to count block crossings, that is, pairs of intersecting bundles of lines. In a block crossing, two blocks of parallel lines intersect each other, which is less distracting than the same number of individual crossings being spread over the drawing. In this paper, we show that minimizing the number of block crossings is NP-hard, even if all meetings are of size 2. For this special case, we present a greedy heuristic, which we evaluate experimentally. We show that the general case is fixed-parameter tractable. Our main results is a constant-factor approximation algorithm for meetings of bounded size. The algorithm is based on (approximately) solving a hyperedge deletion problem on hypergraphs that may be of independent interest.
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Seufert, M.: EdgeNetworkCloudSim: Placement of Service Chains in Edge Clouds Using NetworkCloudSim. , 1st IEEE International Workshop on Network Programmability - From the Data Center to the Ground (NetFoG), Bologna, Italy (2017).
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Bente, G., Roth, D., Al-Issa, A.: Beyond Stereotypes: Using VR-based Methods in Nonverbal Communication Research. (2017).
The contribution aims to demonstrate the value of computational methods from Virtual Reality (VR) for the study of nonverbal communication and person perception. Focusing on gender and cultural differences in “nonverbal rapport” we will show how motion capture technology and character animation can help overcome stereotype influence and judgment biases in observation studies and at the same time provide deeper insights into the behavioral dynamics of nonverbal communication. Specific algorithms and software tools for continuous impression ratings, parameter extraction from dyadic movement protocols and integrated analysis of impressions and behavioral data will be introduced. Future prospects for other areas of nonverbal communication research will be outlined.
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Zinner, T.: QoE-Aware Service And Network Management for Video Streaming. , NewNet@Paris Lab, Telecom ParisTech, France (http://perso.telecom-paristech.fr/~drossi/index.php?n=Main.Seminar#KEY20170920) (2017).
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Abd El Hai, S.: Measuring the Applicability of the Analytic Model for SDN Controller Traffic and Switch Table Occupancy, (2017).
In the paper 'Analytic Model for SDN Controller Traffic and Switch Table Occupancy' a model has been created and later been verified by simulation. The next step is to test the applicability of the model by measurements. The task is to create a testbed and methods to accomplish this. <christopher.metter@informatik.uni-wuerzburg.de>
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Martin, D., Carpendale, S., Gupta, N., Hoßfeld, T., Naderi, B., Redi, J., Siahaan, E., Wechsung, I.: Understanding The Crowd: Ethical and Practical Matters in the Academic Use of Crowdsourcing. In: Archambault, D., Hoßfeld, T., und Purchase, H.C. (hrsg.) Evaluation in the Crowd: Crowdsourcing and Human-Centred Experiments. Springer (2017).
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Schaper, P., Grundgeiger, T.: The role of cognitive load and suppression in commission errors. Conference of the European Society for Cognitive Psychology (2017).
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Wiebusch, D., Zimmerer, C., Latoschik, M.E.: Cherry-Picking RIS Functionality -- Integration of Game and VR Engine Sub-Systems based on Entities and Events. 10th Workshop on Software Engineering and Architectures for Realtime Interactive Systems (SEARIS). IEEE Computer Society (2017).
Modern game engines provide a variety of high-end features and sub-systems which have made them increasingly interesting for AR/VR research. Here, it often is necessary to combine features from different sources. This paper presents an approach based on entity-event state decoupling and exchange. The approach targets the combination of sub-systems from different sources which simulate functionally coherent aspects of the virtual objects like physics, graphics, AI, or developer services like state editing. The approach decouples specific internal representations using a semantic description layer for identifiers, data types, and potential relations between them. We illustrate the main concepts using examples from the combination of the Unreal Engine 4, the Unity engine, and own research software and illustrate performance related aspects as a guideline for the choice of an appropriate transport layer.
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Sträßer, M.: SDN-based Elephant Detection, (2017).
ZOOM is an SDN based approach for elephant detection in SDN enabled networks. The idea is to split the IP address space into sections that are iteratively refined until only the largest flows remain. These are then returned as elephant flows. A proof-of-concept implementation and basic evaluation has already been performed in the paper emphZOOM: Lightweight SDN-based Elephant Detection.
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Hoßfeld, T., Fiedler, M., Gustafsson, J.: Betas: Deriving Quantiles from MOS-QoS Relations of IQX Models for QoE Management. IFIP/IEEE International Workshop on Quality of Experience Management (QoE-Management). , Lisbon, Portugal (2017).
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Lareida, A., Hoßfeld, T., Stiller, B.: The BitTorrent Peer Collector Problem. IFIP/IEEE International Symposium on Integrated Network Management. , Lisbon, Portugal (2017).
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Hoßfeld, T., Heegaard, P.E., Skorin-Kapov, L., Varela, M.: No Silver Bullet: QoE Metrics, QoE Fairness, and User Diversity in the Context of QoE Management. 9th International Conference on Quality of Multimedia Experience (QoMEX 2017). , Erfurt, Germany (2017).
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Niebler, T., Becker, M., Pölitz, C., Hotho, A.: Learning Semantic Relatedness from Human Feedback Using Relative Relatedness Learning. Proceedings of the ISWC 2017 Posters & Demonstrations and Industry Tracks co-located with 16th International Semantic Web Conference (ISWC 2017) (2017).
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Pfaff, B., Scherer, J., Hock, D., Gray, N., Zinner, T., Tran-Gia, P., Durner, R., Kellerer, W., Lorenz, C.: SDN/NFV-enabled Security Architecture for Fine-grained Policy Enforcement and Threat Mitigation for Enterprise Networks, (2017).
Network Functions Visualization (NFV) replaces physical middleboxes with software instances running network functions in cloud environments. To support this new paradigm, it is necessary to port the code basis from highly specialized hardware devices to virtual machines running on COTS hardware. In order to fully exploit the inherent capabilities of cloud environments it is further necessary to redesign the software to support a large amount of distributed, cooperating function instances instead of single, isolated and monolithic instances. This development can be observed for network functions like stateful firewalling. Until now, available software firewalls lack support for active/active operation in clustered environments, which hinders horizontal scalability. This is due to the fact that the required synchronization of connection states among the cluster's instances is an impediment that still has to be resolved. Therefore, this work investigates different synchronization strategies and mechanisms, which allow to share connection states among the cluster to maintain scalability and high-availability.
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Horst-Schaper, G., Kumar, D.S., Schaper, P.: [POSTER] Patientenübergriffe - ein Thema für Betriebsärzte im Krankenhaus?!. 57th Wissenschaftliche Jahrestagung der Deutschen Gesellschaft für Arbeitsmedizin und Umweltmedizin e.V. (2017).
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Roth, D., Lugrin, J.-L., von Mammen, S., Latoschik, M.E.: Controllers & Inputs: Masters of Puppets. In: Banks, J. (hrsg.) Digital Formations. S. 281-290. Peter Lang (2017).
Avatar, Assembled is a curated volume that unpacks videogame and virtual world avatars—not as a monolithic phenomenon (as they are usually framed) but as sociotechnical assemblages, pieced together from social (human-like) features like voice and gesture to technical (machine-like) features like graphics and glitches. Each chapter accounts for the empirical, theoretical, technical, and popular understandings of these avatar “compo- nents”—60 in total—altogether offering a nuanced explication of avatars-as-assemblages as they matter in contemporary soci- ety and in individual experience. The volume is a “crossover” piece in that, while it delves into complex ideas, it is written in a way that will be accessible and interesting to students, researchers, designers, and practitioners alike.
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Knapp, T.: Extending the Monitoring Features of ONOS, (2017).
The SDN controller ONOS lacks certain network monitoring capabilities. The task is to develop an ONOS application which utilizes the interfaces provided by ONOS and enableds the active measurement of a predefined set of network metrics.
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van Dijk, T.C., Fink, M., Fischer, N., Lipp, F., Markfelder, P., Ravsky, A., Suri, S., Wolff, A.: Block Crossings in Storyline Visualizations. Journal of Graph Algorithms & Applications. 21, 873--913 (2017).
Storyline visualizations help visualize encounters of the characters in a story over time. Each character is represented by an x-monotone curve that goes from left to right visualizing progression of time. A meeting is represented by having the characters that participate in the meeting run close together for some time. In order to keep the visual complexity low, rather than just minimizing pairwise crossings of curves, we propose to count block crossings, that is, pairs of intersecting bundles of lines. In a block crossing, two blocks of parallel lines intersect each other, which is less distracting than the same number of individual crossings being spread over the drawing. In this paper, we show that minimizing the number of block crossings is NP-hard, even if all meetings are of size 2. For this special case, we present a greedy heuristic, which we evaluate experimentally. We show that the general case is fixed-parameter tractable. Our main results is a constant-factor approximation algorithm for meetings of bounded size. The algorithm is based on (approximately) solving a hyperedge deletion problem on hypergraphs that may be of independent interest.
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Pfaff, B.: Evaluation of a Distributed Control Plane for Managing Heterogeneous SDN and Legacy Networks, (2017).
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Wehner, N.: Simulative Evaluation of the QoE Fairness of HAS Adaptation Logics, (2017).
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Schwarzmann, S., Zinner, T., Dobrijevic, O.: Quantitative Comparison of Application-Network Interaction: A Case Study of Adaptive Video Streaming. Springer Quality and User Experience. (2017).
Managing quality of experience (QoE) is now widely accepted as a critical objective for multimedia applications and the supporting communication systems. In general, QoE management encompasses: (i) monitoring of the key influence factors and QoE indicators, and (ii) deciding on the appropriate control actions as specified by the management goal. Many multimedia applications, e.g. video streaming and audio conferencing, are able to adjust their operational parameters so as to react to variations in the network performance. However, such an adaptation feature is mostly based on a local client view of the network conditions, which may lead to an unfair allocation of network resources among heterogeneous clients and, thus, an unfair QoE distribution. In order to tackle this issue, there is the call for a cooperation between the applications and the underlying network, which includes application-network interaction (App-Net) in terms of: (1) exchanging information on the monitored QoE indicators, and (2) coordinating the QoE control actions. Various App-Net mechanisms focusing on specific use cases and applications have been proposed to date. This paper gives an overview of App-Net mechanisms and proposes a generic App-Net model that provides the means to realize a coordinated QoE-centric management. Based on the App-Net model, we develop an evaluation methodology to compare three App-Net mechanisms for managing QoE of HTTP adaptive streaming (HAS) against a baseline HAS service. The aim of this quantitative comparison is to explore the trade-offs between QoE gains and the complexity of App-Net implementation, with respect to the number of monitoring and control messages, achieved video quality, and QoE fairness among heterogeneous clients. Our ultimate goal is to set up reproducible experiments that facilitate a holistic evaluation of different App-Net mechanisms.
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Lemmerich, F., Singer, P., Becker, M., Espin-Noboa, L., Dimitrov, D., Helic, D., Hotho, A., Strohmaier, M.: Comparing Hypotheses About Sequential Data: A Bayesian Approach and Its Applications. In: Altun, Y., Das, K., Mielikäinen, T., Malerba, D., Stefanowski, J., Read, J., vZitnik, M., Ceci, M., und Dvzeroski, S. (hrsg.) Machine Learning and Knowledge Discovery in Databases. S. 354--357. Springer International Publishing, Cham (2017).
Sequential data can be found in many settings, e.g., as sequences of visited websites or as location sequences of travellers. To improve the understanding of the underlying mechanisms that generate such sequences, the HypTrails approach provides for a novel data analysis method. Based on first-order Markov chain models and Bayesian hypothesis testing, it allows for comparing a set of hypotheses, i.e., beliefs about transitions between states, with respect to their plausibility considering observed data. HypTrails has been successfully employed to study phenomena in the online and the offline world. In this talk, we want to give an introduction to HypTrails and showcase selected real-world applications on urban mobility and reading behavior on Wikipedia.
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Zach, O., Seufert, M., Hirth, M., Slanina, M., Tran-Gia, P.: On Use of Crowdsourcing for H.264/AVC and H.265/HEVC Video Quality Evaluation. Radioelektronika. , Brno, Czech Republic (2017).
Crowdsourcing has become a popular method in the field of video quality evaluation. Gathering the opinion of the users using crowdsourcing is quick and relatively cheap but such a study has to be designed very carefully in order to give relevant results. So far, the majority of the QoE studies using crowdsourcing has been focusing on the performance of H.264/AVC algorithm in different situations (such as encoder settings, stalling effects, etc). Modern video coding methods, however, are only rarely tested using the crowdsourcing approach. We designed a study comparing the performance of both H.264/AVC and H.265/HEVC standards in the crowdsourcing environment. We deal with the possibilities of delivering and presenting the HEVC encoded content to the participants of the crowdsourcing study and potential challenges. Finally, the study was performed using Microworkers platform and gathered results are then compared with three different objective video quality metrics.
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Loh, F.: Performance Evaluation of Service Chains in Cloud Networks Using Discrete-Time Analysis, (2017).
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Bott, L.: Implementing Backup Paths and Recovery Strategies in an SDN controlled by ONOS, (2017).
As the migration towards SDN is in progress, the satisfaction of carrier-grade requirements (fast failure detection, fast reaction, high availability throughout the year) becomes more and more important. The SDN controller ONOS already provides promising mechanisms and tools, but lacks certain capabilities. The task of the project is to enhance ONOS capabilities by implementing the provisioning of backup paths and recovery strategies. <christopher.metter@informatik.uni-wuerzburg.de>
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Sommer, M.: Implementation of an OpenFlow Fuzzing Framework, (2017).
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Seufert, M., Zach, O., Slanina, M., Tran-Gia, P.: Unperturbed Video Streaming QoE Under Web Page Related Context Factors. 9th International Conference on Quality of Multimedia Experience (QoMEX). , Erfurt, Germany (2017).
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