[92] | Christian Timmerer, MPEG column: 121st MPEG meeting in Gwangju, Korea, In SIGMultimedia Records, ACM, vol. 10, no. 1, New York, NY, USA, pp. 6:6-6:6, 2018.
[bib][url] [doi] |
[91] | Christian Timmerer, MPEG Column: 120th MPEG Meeting in Macau, China, In SIGMultimedia Records, ACM, vol. 9, no. 3, New York, NY, USA, pp. 4:4-4:4, 2018.
[bib][url] [doi] |
[90] | Evsen Yanmaz, Saeed Yahyanejad, Bernhard Rinner, Hermann Hellwagner, Christian Bettstetter, Drone networks: Communications, coordination, and sensing, In Ad Hoc Networks, Elsevier, vol. 68, Amsterdam, pp. 1-15, 2018.
[bib][url] [doi] [abstract]
Abstract: Small drones are being utilized in monitoring, transport, safety and disaster management, and other domains. Envisioning that drones form autonomous networks incorporated into the air traffic, we describe a high-level architecture for the design of a collaborative aerial system consisting of drones with on-board sensors and embedded processing, coordination, and networking capabilities. We implement a multi-drone system consisting of quadcopters and demonstrate its potential in disaster assistance, search and rescue, and aerial monitoring. Furthermore, we illustrate design challenges and present potential solutions based on the lessons learned so far.
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[89] | Daniela Pohl, Abdelhamid Bouchachia, Hermann Hellwagner, Batch-based active learning: Application to social media data for crisis management, In Expert Systems with Applications, Elsevier Ltd., vol. 93, Amsterdam, pp. 232-244, 2018.
[bib][url] [doi] [abstract]
Abstract: Classification of evolving data streams is a challenging task, which is suitably tackled with online learning approaches. Data is processed instantly requiring the learning machinery to (self-)adapt by adjusting its model. However for high velocity streams, it is usually difficult to obtain labeled samples to train the classification model. Hence, we propose a novel online batch-based active learning algorithm (OBAL) to perform the labeling. OBAL is developed for crisis management applications where data streams are generated by the social media community. OBAL is applied to discriminate relevant from irrelevant social media items. An emergency management user will be interactively queried to label chosen items. OBAL exploits the boundary items for which it is highly uncertain about their class and makes use of two classifiers: k-Nearest Neighbors (kNN) and Support Vector Machine (SVM). OBAL is equipped with a labeling budget and a set of uncertainty strategies to identify the items for labeling. An extensive analysis is carried out to show OBAL’s performance, the sensitivity of its parameters, and the contribution of the individual uncertainty strategies. Two types of datasets are used: synthetic and social media datasets related to crises. The empirical results illustrate that OBAL has a very good discrimination power.
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[88] | Anatoliy Zabrovskiy, Evgeny Petrov, Evgeny Kuzmin, Christian Timmerer, Evaluation of the Performance of Adaptive HTTP Streaming Systems, In arXiv.org [cs.MM], N.N., vol. abs/1710.02459, N.N., pp. 7, 2017.
[bib][url] [pdf] [abstract]
Abstract: Adaptive video streaming over HTTP is becoming omnipresent in our daily life. In the past, dozens of research papers have proposed novel approaches to address different aspects of adaptive streaming and a decent amount of player implementations (commercial and open source) are available. However, state of the art evaluations are sometimes superficial as many proposals only investigate a certain aspect of the problem or focus on a specific platform – player implementations used in actual services are rarely considered. HTML5 is now available on many platforms and foster the deployment of adaptive media streaming applications. We propose a common evaluation framework for adaptive HTML5 players and demonstrate its applicability by evaluating eight different players which are actually deployed in real-world services.
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[87] | Christian Timmerer, Immersive Media Delivery: Overview of Ongoing Standardization Activities, In IEEE Communications Standards Magazine, IEEE Communications Society, vol. 1, no. 4, N.N., pp. 71-74, 2017.
[bib] [doi] [pdf] [abstract]
Abstract: More and more immersive media applications and services are emerging on the market, but lack international standards to enable interoperability. This article provides an overview about ongoing standardization efforts in this exciting domain and highlights open research and standardization issues.
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[86] | Christian Timmerer, Ali Cengiz Begen, Advancing Multimedia Content Distribution, In Computing Now, IEEE Computer Society [online], Los Alamitos, CA, USA, pp. 1, 2017.
[bib][url] |
[85] | Christian Timmerer, MPEG Column: 116th MPEG Meeting, In SIGMultimedia Records, ACM, vol. 8, no. 4, New York, NY, USA, pp. N.N., 2017.
[bib][url] [doi] |
[84] | Christian Timmerer, MPEG Column: 117th MPEG Meeting, In SIGMultimedia Records, ACM, vol. 9, no. 1, New York, NY, USA, pp. N.N., 2017.
[bib][url] [doi] |
[83] | Christian Timmerer, MPEG Column: 118th MPEG Meeting, In SIGMultimedia Records, ACM, vol. 8, no. 4, New York, NY, USA, pp. N.N., 2017.
[bib][url] [doi] |
[82] | Christian Timmerer, MPEG Column: 119th MPEG Meeting in Turin, Italy, In SIGMultimedia Records, ACM, vol. 9, no. 2, New York, NY, USA, pp. N.N., 2017.
[bib][url] [doi] |
[81] | Christian Timmerer, Report from ACM MMSys 2017, In SIGMultimedia Records, ACM, vol. 9, no. 2, New York, NY, USA, pp. N.N., 2017.
[bib][url] [doi] |
[80] | Christian Timmerer, Ali Cengiz Begen, Best Papers of the 2016 ACM Multimedia Systems (MMSys) Conference and Workshop on Network and Operating System Support for Digital Audio and Video (NOSSDAV) 2016, In ACM Transactions on Multimedia Computing, Communications, and Applications (TOMM), ACM Digital Library, vol. 13, no. 3s, New York, NY, USA, pp. 40:1-40:2, 2017.
[bib][url] [doi] [pdf] |
[79] | Benjamin Rainer, Stefan Petscharnig, Christian Timmerer, Hermann Hellwagner, Statistically Indifferent Quality Variation: An Approach for Reducing Multimedia Distribution Cost for Adaptive Video Streaming Services, In IEEE Transactions on Multimedia, IEEE, vol. 19, New York, USA, pp. 13, 2017.
[bib][url] [doi] [pdf] [abstract]
Abstract: Forecasts predict that Internet traffic will continue to grow in the near future. A huge share of this traffic is caused by multimedia streaming. The Quality of Experience (QoE) of such streaming services is an important aspect and in most cases the goal is to maximize the bit rate which -- in some cases -- conflicts with the requirements of both consumers and providers. For example, in mobile environments users may prefer a lower bit rate to come along with their data plan. Likewise, providers aim at minimizing bandwidth usage in order to reduce costs by transmitting less data to users while maintaining a high QoE. Today's adaptive video streaming services try to serve users with the highest bit rates which consequently results in high QoE. In practice, however, some of these high bit rate representations may not differ significantly in terms of perceived video quality compared to lower bit rate representations. In this paper, we present a novel approach to determine the statistically indifferent quality variation (SIQV) of adjacent video representations for adaptive video streaming services by adopting standard objective quality metrics and existing QoE models. In particular, whenever the quality variation between adjacent representations is imperceptible from a statistical point of view, the representation with higher bit rate can be substituted with a lower bit rate representation. As expected, this approach results in savings with respect to bandwidth consumption while still providing a high QoE for users. The approach is evaluated subjectively with a crowdsourcing study. Additionally, we highlight the benefits of our approach, by providing a case study that extrapolates possible savings for providers.
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[78] | Daniel Posch, Benjamin Rainer, Hermann Hellwagner, SAF: Stochastic Adaptive Forwarding in Named Data Networking, In IEEE/ACM Transactions on Networking, IEEE, vol. 25, no. 2, New York, USA, pp. 14, 2017.
[bib][url] [doi] [pdf] [abstract]
Abstract: Forwarding decisions in classical IP-based networks are predetermined by routing. This is necessary to avoid loops, inhibiting opportunities to implement an adaptive and intelligent forwarding plane. Consequently, content distribution efficiency is reduced due to a lack of inherent multi-path transmission. In Named Data Networking (NDN) instead, routing shall hold a supporting role to forwarding, providing sufficient potential to enhance content dissemination at the forwarding plane. In this paper we design, implement, and evaluate a novel probability-based forwarding strategy, called Stochastic Adaptive Forwarding (SAF) for NDN. SAF imitates a self-adjusting water pipe system, intelligently guiding and distributing Interests through network crossings circumventing link failures and bottlenecks. Just as real pipe systems, SAF employs overpressure valves enabling congested nodes to lower pressure autonomously. Through an implicit feedback mechanism it is ensured that the fraction of the traffic forwarded via congested nodes decreases. By conducting simulations we show that our approach outperforms existing forwarding strategies in terms of the Interest satisfaction ratio in the majority of the evaluated scenarios. This is achieved by extensive utilization of NDN's multipath and content-lookup capabilities without relying on the routing plane. SAF explores the local environment by redirecting requests that are likely to be dropped anyway. This enables SAF to identify new paths to the content origin or to cached replicas, circumventing link failures and resource shortages without relying on routing updates.
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[77] | Daniel Posch, Benjamin Rainer, Hermann Hellwagner, Towards a Context-Aware Forwarding Plane in Named Data Networking supporting QoS, In Computer Communication Review, ACM SIGCOMM, vol. 47, no. 1, New York, USA, pp. 9, 2017.
[bib][url] [doi] [pdf] [abstract]
Abstract: The emergence of Information-Centric Networking (ICN) provides considerable opportunities for context-aware data distribution in the network's forwarding plane. While packet forwarding in classical IP-based networks is basically predetermined by routing, ICN foresees an adaptive forwarding plane considering the requirements of network applications. As research in this area is still at an early stage, most of the work so far focused on providing the basic functionality, rather than on considering the available context information to improve Quality of Service (QoS). This article investigates to which extent existing forwarding strategies take account of the available context information and can therefore increase service quality. The article examines a typical scenario encompassing different user applications (Voice over IP, video streaming, and classical data transfer) with varying demands (context), and evaluates how well the applications' requirements are met by the existing strategies.
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[76] | Antonio Pinheiro, Christian Timmerer, Standards Column: JPEG and MPEG, In SIGMultimedia Records, ACM, vol. 9, no. 1, New York, NY, USA, pp. N.N., 2017.
[bib][url] [doi] |
[75] | X Zhu, S Mao, M Hassan Hassan, Hermann Hellwagner, Guest Editorial: Video Over Future Networks, In IEEE Transactions on Multimedia, IEEE, vol. 19, no. 10, Piscataway, NJ, pp. 2133 - 2135, 2017.
[bib][url] [doi] [abstract]
Abstract: The papers in this special issue focus on the deployment of video over future networks. The past decade has seen how major improvements in broadband and mobile networks have led to widespread popularity of video streaming applications, and how the latter now becomes the major driving force behind exponentially growing Internet traffic. This special issue seeks to investigate these future Internet technologies through the prism of its most prevalent application, that of video communications. video.
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[74] | Christian Timmerer, The Future of Multimedia on the Internet, In Computing Now, IEEE Computer Society [online], Los Alamitos, CA, USA, pp. 1, 2016.
[bib][url] |
[73] | Cedric Westphal, Tommaso Melodia, Wenww Zhu, Christian Timmerer, Guest Editorial Video Distribution Over Future Internet, In IEEE Journal on Selected Areas in Communications, IEEE Communications Society, vol. 34, no. 8, New York, pp. 2061-2062, 2016.
[bib] [pdf] |
[72] | Christian Timmerer, Matteo Maiero, Benjamin Rainer, Which Adaptation Logic? An Objective and Subjective Performance Evaluation of HTTP-based Adaptive Media Streaming Systems, In arXiv.org [cs.MM], N.N., vol. abs/1606.00341, N.N., pp. 11, 2016.
[bib][url] [pdf] |
[71] | Christian Timmerer, Alan Bertoni, Advanced Transport Options for the Dynamic Adaptive Streaming over HTTP, In arXiv.org [cs.MM], N.N., vol. abs/1606.00264, N.N., pp. 6, 2016.
[bib][url] [pdf] |
[70] | Benjamin Rainer, Daniel Posch, Andreas Leibetseder, Sebastian Theuermann, Hermann Hellwagner, A Low-Cost NDN Testbed on Banana Pi Routers, In Communications Magazine, IEEE, IEEE, vol. 54, no. 9, New York, USA, pp. 6, 2016. (IEEE COMMAG Network Testing and Analytics Series)
[bib] [pdf] [abstract]
Abstract: The computer communication research community shows significant interest in the paradigm of Information-Centric Networking (ICN). Continuously, new proposals for ICN-related challenges (caching, forwarding, etc.) are published. However, due to a lack of a readily available testbed, the majority of these proposals is evaluated either by theoretical analysis and/or by conducting network simulations potentially masking further challenges that are not observable in synthetic environments. Therefore, this article presents a framework for an ICN testbed using low-budget physical hardware with little deployment and maintenance effort for the individual researcher; specifically, Named Data Networking is considered. The employed hardware and software are powerful enough for most research projects, but extremely resource intensive tasks may push both components towards their limits. The testbed framework is based on well established open source software and provides the tools to readily investigate important ICN characteristics on physical hardware emulating arbitrary network topologies. The article discusses the testbed architecture and provides first results obtained from emulations that investigate the performance of various forwarding strategies. The results indicate that further challenges have to be overcome when heading towards a real-world deployment of ICN-based communication.
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[69] | Benjamin Rainer, Daniel Posch, Hermann Hellwagner, Investigating the Performance of Pull-based Dynamic Adaptive Streaming in NDN, In Journal on Selected Areas in Communications, IEEE, vol. 34, no. 8, New York, USA, pp. 11, 2016. (IEEE JSAC Special Issue on Video Distribution over Future Internet)
[bib] [doi] [pdf] [abstract]
Abstract: Adaptive content delivery is the state-of-the-art in real-time multimedia streaming. Leading streaming approaches, e.g., MPEG-DASH and Apple HLS, have been developed for classical IP-based networks, providing effective streaming by means of pure client-based control and adaptation. However, the research activities of the Future Internet community adopt a new course that is different from today's host-based communication model. So-called Information-Centric Networks are of considerable interest and are advertised as enablers for intelligent networks, where effective content delivery is to be provided as an inherent network feature. This paper investigates the performance gap between pure client-driven adaptation and the theoretical optimum in the promising Future Internet architecture Named Data Networking (NDN). The theoretical optimum is derived by modeling multimedia streaming in NDN as a fractional Multi-Commodity Flow Problem and by extending it taking caching into account. We investigate the multimedia streaming performance under different forwarding strategies, exposing the interplay of forwarding strategies and adaptation mechanisms. Furthermore, we examine the influence of network inherent caching on the streaming performance by varying the caching polices and the cache sizes.
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[68] | Christian Timmerer, Touradj Ebrahimi, Fernando Pereira, Toward a New Assessment of Quality, In IEEE Computer, IEEE Computer Society, vol. 48, no. 3, Los Alamitos, CA, USA, pp. 108-110, 2015.
[bib] [pdf] [abstract]
Abstract: A convergence of trends is shifting the focus of quality assessment from compliance with system design goals to fulfillment of user needs or expectations in different contexts.
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