Dr. rer. nat. Valentin Burger

• Towards an Active Probing Extension for the {ONOS} {SDN} Controller. Metter, Christopher; Burger, Valentin; Hu, Zheng; Pei, Ke; Wamser, Florian. In 2018 28th International Telecommunication Networks and Applications Conference (ITNAC) (ITNAC 2018), p. 8. Sydney, Australia, 2018.
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  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.

  @inproceedings{info3-inproceedings-2018-34, abstract = {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.}, address = {Sydney, Australia}, author = {Metter, Christopher and Burger, Valentin and Hu, Zheng and Pei, Ke and Wamser, Florian}, booktitle = {2018 28th International Telecommunication Networks and Applications Conference (ITNAC) (ITNAC 2018)}, keywords = {can}, month = 11, pages = 8, title = {Towards an Active Probing Extension for the {ONOS} {SDN} Controller}, year = 2018 }

  %0 Conference Paper %1 info3-inproceedings-2018-34 %A Metter, Christopher %A Burger, Valentin %A Hu, Zheng %A Pei, Ke %A Wamser, Florian %B 2018 28th International Telecommunication Networks and Applications Conference (ITNAC) (ITNAC 2018) %C Sydney, Australia %D 2018 %P 8 %T Towards an Active Probing Extension for the {ONOS} {SDN} Controller %X 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.
• A Generic Approach to Video Buffer Modeling using Discrete-Time Analysis. Burger, Valentin; Zinner, Thomas; Dinh-Xuan, Lam; Wamser, Florian; Tran-Gia, Phuoc. In ACM Transactions on Multimedia Computing, Communications, and Applications (TOMM), 14(33), p. 23. 2018.
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  @article{info3-article-2018-1, author = {Burger, Valentin and Zinner, Thomas and Dinh-Xuan, Lam and Wamser, Florian and Tran-Gia, Phuoc}, journal = {ACM Transactions on Multimedia Computing, Communications, and Applications (TOMM)}, keywords = {sys:hidden:article}, month = {04}, number = 33, pages = 23, title = {A Generic Approach to Video Buffer Modeling using Discrete-Time Analysis}, volume = 14, year = 2018 }

  %0 Journal Article %1 info3-article-2018-1 %A Burger, Valentin %A Zinner, Thomas %A Dinh-Xuan, Lam %A Wamser, Florian %A Tran-Gia, Phuoc %D 2018 %J ACM Transactions on Multimedia Computing, Communications, and Applications (TOMM) %N 33 %P 23 %T A Generic Approach to Video Buffer Modeling using Discrete-Time Analysis %V 14
• Impact of VNF Placements on QoE Monitoring in the Cloud. Dinh-Xuan, Lam; Popp, Christian; Burger, Valentin; Wamser, Florian; Hoßfeld, Tobias. In International Journal of Network Management, (NEM-18-0120.R1). 2018.
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  @article{info3-article-2018-6, author = {Dinh-Xuan, Lam and Popp, Christian and Burger, Valentin and Wamser, Florian and Hoßfeld, Tobias}, journal = {International Journal of Network Management}, keywords = {video-quality}, month = 10, number = {NEM-18-0120.R1}, title = {Impact of VNF Placements on QoE Monitoring in the Cloud}, year = 2018 }

  %0 Journal Article %1 info3-article-2018-6 %A Dinh-Xuan, Lam %A Popp, Christian %A Burger, Valentin %A Wamser, Florian %A Hoßfeld, Tobias %D 2018 %J International Journal of Network Management %N NEM-18-0120.R1 %T Impact of VNF Placements on QoE Monitoring in the Cloud
• Evaluation of the Detection Capabilities of the ONOS SDN Controller. Metter, Christopher; Burger, Valentin; Hu, Zheng; Pei, Ke; Wamser, Florian. In 7th IEEE International Conference on Communications and Electronics (IEEE ICCE 2018), pp. 96–101. Hue, Vietnam, 2018.
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  The process of monitoring the network, especially for larger ones, is very complex and contains many pitfalls. For instance the balance between granularity of information and their performance impact on the network. With the help of SDN this challenge can become easier, as it offers new methods, mechanisms and opportunities. One of the current most important Open Source controllers is the ONOS SDN controller. According to its developers it is a production ready controller that offers high availability due to its logically centralized and physically distributed architecture. But, as our investigations show, it is unable to cope with hazardous network conditions such as sporadic or recurring packet loss. It either does not detect packet loss or only detects it after long time periods, failing all common network availability targets.

  @inproceedings{info3-inproceedings-2018-22, abstract = {The process of monitoring the network, especially for larger ones, is very complex and contains many pitfalls. For instance the balance between granularity of information and their performance impact on the network. With the help of SDN this challenge can become easier, as it offers new methods, mechanisms and opportunities. One of the current most important Open Source controllers is the ONOS SDN controller. According to its developers it is a production ready controller that offers high availability due to its logically centralized and physically distributed architecture. But, as our investigations show, it is unable to cope with hazardous network conditions such as sporadic or recurring packet loss. It either does not detect packet loss or only detects it after long time periods, failing all common network availability targets.}, address = {Hue, Vietnam}, author = {Metter, Christopher and Burger, Valentin and Hu, Zheng and Pei, Ke and Wamser, Florian}, booktitle = {7th IEEE International Conference on Communications and Electronics (IEEE ICCE 2018)}, keywords = {can}, month = {07}, pages = {96 - 101}, title = {Evaluation of the Detection Capabilities of the ONOS SDN Controller}, year = 2018 }

  %0 Conference Paper %1 info3-inproceedings-2018-22 %A Metter, Christopher %A Burger, Valentin %A Hu, Zheng %A Pei, Ke %A Wamser, Florian %B 7th IEEE International Conference on Communications and Electronics (IEEE ICCE 2018) %C Hue, Vietnam %D 2018 %P 96 - 101 %T Evaluation of the Detection Capabilities of the ONOS SDN Controller %X The process of monitoring the network, especially for larger ones, is very complex and contains many pitfalls. For instance the balance between granularity of information and their performance impact on the network. With the help of SDN this challenge can become easier, as it offers new methods, mechanisms and opportunities. One of the current most important Open Source controllers is the ONOS SDN controller. According to its developers it is a production ready controller that offers high availability due to its logically centralized and physically distributed architecture. But, as our investigations show, it is unable to cope with hazardous network conditions such as sporadic or recurring packet loss. It either does not detect packet loss or only detects it after long time periods, failing all common network availability targets.

• Performance Evaluation of Video Streaming Service Chains in Softwarized 5G Networks with Task Graph Reduction. Loh, Frank; Burger, Valentin; Wamser, Florian; Tran-Gia, Phuoc; Schembra, Giovanni; Rametta, Corrado. In 29th International Teletraffic Congress (ITC). 2017.
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  @inproceedings{info3-inproceedings-2017-18, author = {Loh, Frank and Burger, Valentin and Wamser, Florian and Tran-Gia, Phuoc and Schembra, Giovanni and Rametta, Corrado}, booktitle = {29th International Teletraffic Congress (ITC)}, keywords = {can}, month = {09}, title = {Performance Evaluation of Video Streaming Service Chains in Softwarized 5G Networks with Task Graph Reduction}, year = 2017 }

  %0 Conference Paper %1 info3-inproceedings-2017-18 %A Loh, Frank %A Burger, Valentin %A Wamser, Florian %A Tran-Gia, Phuoc %A Schembra, Giovanni %A Rametta, Corrado %B 29th International Teletraffic Congress (ITC) %D 2017 %T Performance Evaluation of Video Streaming Service Chains in Softwarized 5G Networks with Task Graph Reduction
• Performance Evaluation and Optimization of Content Delivery Networks. Technical Report (PhD dissertation), . Burger, Valentin. PhD dissertation. University of Wuerzburg, 2017, July.
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  @phdthesis{info3-dissertation-2017-2, author = {Burger, Valentin}, keywords = {sys:hidden:supervisor:phuoc.tran-gia}, month = {07}, school = {University of Wuerzburg}, title = {Performance Evaluation and Optimization of Content Delivery Networks}, year = 2017 }

  %0 Thesis %1 info3-dissertation-2017-2 %A Burger, Valentin %D 2017 %T Performance Evaluation and Optimization of Content Delivery Networks
• An Approximation of the Backhaul Bandwidth Aggregation Potential Using a Partial Sharing Scheme. Burger, Valentin; Seufert, Michael; Zinner, Thomas; Tran-Gia, Phuoc. In 15th IFIP/IEEE International Symposium on Integrated Network Management (IM). Lisbon, Portugal, 2017.
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  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.

  @inproceedings{info3-inproceedings-2017-1, abstract = {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.}, address = {Lisbon, Portugal}, author = {Burger, Valentin and Seufert, Michael and Zinner, Thomas and Tran-Gia, Phuoc}, booktitle = {15th IFIP/IEEE International Symposium on Integrated Network Management (IM)}, keywords = {can}, month = {05}, title = {An Approximation of the Backhaul Bandwidth Aggregation Potential Using a Partial Sharing Scheme}, year = 2017 }

  %0 Conference Paper %1 info3-inproceedings-2017-1 %A Burger, Valentin %A Seufert, Michael %A Zinner, Thomas %A Tran-Gia, Phuoc %B 15th IFIP/IEEE International Symposium on Integrated Network Management (IM) %C Lisbon, Portugal %D 2017 %T An Approximation of the Backhaul Bandwidth Aggregation Potential Using a Partial Sharing Scheme %X 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.
• Viability of Wi-Fi Caches in an Era of HTTPS Prevalence. Moldovan, Christian; Burger, Valentin; Metzger, Florian; Surminski, Sebastian; Hoßfeld, Tobias. In 2017 IEEE International Conference on Communications Workshops (ICC Workshops). Paris, France, 2017.
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  Caches are often employed to better manage the ever-growing amount of global Internet traffic. Particularly, reverse proxies are often used to free up congested peering links and reduce inter-domain traffic. In addition, caches place content close to the edge, leading to lower latency which can be beneficial for many applications. In an effort to bring content even closer to end devices, home routers and public access points are now in the spotlight as a novel location for caches. Compared to CDNs, a Wi-Fi router only offers scarce storage and processing capabilities, putting an increased emphasis on resource management. In addition, a large share of traffic is transmitted through secured connections preventing the use of forward caches and other middle boxes. This paper strives to analyze how effective caching can be in public Wi-Fi routers. For this purpose, we conducted a field study with caches at public Wi-Fi hotspots in a field study. In addition, we present a queueing model for caches that we use to perform a mean-value analysis. We compare results from both methods in a performance analysis. Our results provide insights into difficulties of caching systems that are caused by an increase in the ratio of secured connections in the Internet.

  @inproceedings{info3-inproceedings-2017-8, abstract = {Caches are often employed to better manage the ever-growing amount of global Internet traffic. Particularly, reverse proxies are often used to free up congested peering links and reduce inter-domain traffic. In addition, caches place content close to the edge, leading to lower latency which can be beneficial for many applications. In an effort to bring content even closer to end devices, home routers and public access points are now in the spotlight as a novel location for caches. Compared to CDNs, a Wi-Fi router only offers scarce storage and processing capabilities, putting an increased emphasis on resource management. In addition, a large share of traffic is transmitted through secured connections preventing the use of forward caches and other middle boxes. This paper strives to analyze how effective caching can be in public Wi-Fi routers. For this purpose, we conducted a field study with caches at public Wi-Fi hotspots in a field study. In addition, we present a queueing model for caches that we use to perform a mean-value analysis. We compare results from both methods in a performance analysis. Our results provide insights into difficulties of caching systems that are caused by an increase in the ratio of secured connections in the Internet.}, address = {Paris, France}, author = {Moldovan, Christian and Burger, Valentin and Metzger, Florian and Surminski, Sebastian and Hoßfeld, Tobias}, booktitle = {2017 IEEE International Conference on Communications Workshops (ICC Workshops)}, keywords = {sys:hidden:inproceedings}, month = {05}, title = {Viability of Wi-Fi Caches in an Era of HTTPS Prevalence}, year = 2017 }

  %0 Conference Paper %1 info3-inproceedings-2017-8 %A Moldovan, Christian %A Burger, Valentin %A Metzger, Florian %A Surminski, Sebastian %A Hoßfeld, Tobias %B 2017 IEEE International Conference on Communications Workshops (ICC Workshops) %C Paris, France %D 2017 %T Viability of Wi-Fi Caches in an Era of HTTPS Prevalence %X Caches are often employed to better manage the ever-growing amount of global Internet traffic. Particularly, reverse proxies are often used to free up congested peering links and reduce inter-domain traffic. In addition, caches place content close to the edge, leading to lower latency which can be beneficial for many applications. In an effort to bring content even closer to end devices, home routers and public access points are now in the spotlight as a novel location for caches. Compared to CDNs, a Wi-Fi router only offers scarce storage and processing capabilities, putting an increased emphasis on resource management. In addition, a large share of traffic is transmitted through secured connections preventing the use of forward caches and other middle boxes. This paper strives to analyze how effective caching can be in public Wi-Fi routers. For this purpose, we conducted a field study with caches at public Wi-Fi hotspots in a field study. In addition, we present a queueing model for caches that we use to perform a mean-value analysis. We compare results from both methods in a performance analysis. Our results provide insights into difficulties of caching systems that are caused by an increase in the ratio of secured connections in the Internet.
• Comparison of the Initial Delay for Video Playout Start for Different HTTP-based Transport Protocols. Zinner, Thomas; Geissler, Stefan; Helmschrott, Fabian; Burger, Valentin. In Workshop on Quality of Experience Management. 2017.
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  This paper details a measurement study on the impact of different HTTP-based application layer protocols, namely HTTP/1, HTTP/2 and QUIC, on video streaming performance. In this context we evaluate the influence on the initial delay until video playout is started using the live version of the YouTube platform. Furthermore, we evaluate how different network parameters, i.e. bandwidth, RTTs and packet loss influence the different protocols. This work presents an verview over the characteristics of the compared protocols and presents a detailed measurement methodology on how the data has been obtained. Finally, the observed data is evaluated in the context of YouTube video streaming.

  @inproceedings{info3-inproceedings-2017-6, abstract = {This paper details a measurement study on the impact of different HTTP-based application layer protocols, namely HTTP/1, HTTP/2 and QUIC, on video streaming performance. In this context we evaluate the influence on the initial delay until video playout is started using the live version of the YouTube platform. Furthermore, we evaluate how different network parameters, i.e. bandwidth, RTTs and packet loss influence the different protocols. This work presents an verview over the characteristics of the compared protocols and presents a detailed measurement methodology on how the data has been obtained. Finally, the observed data is evaluated in the context of YouTube video streaming.}, author = {Zinner, Thomas and Geissler, Stefan and Helmschrott, Fabian and Burger, Valentin}, booktitle = {Workshop on Quality of Experience Management}, keywords = {ngn}, month = {02}, title = {Comparison of the Initial Delay for Video Playout Start for Different HTTP-based Transport Protocols}, year = 2017 }

  %0 Conference Paper %1 info3-inproceedings-2017-6 %A Zinner, Thomas %A Geissler, Stefan %A Helmschrott, Fabian %A Burger, Valentin %B Workshop on Quality of Experience Management %D 2017 %T Comparison of the Initial Delay for Video Playout Start for Different HTTP-based Transport Protocols %X This paper details a measurement study on the impact of different HTTP-based application layer protocols, namely HTTP/1, HTTP/2 and QUIC, on video streaming performance. In this context we evaluate the influence on the initial delay until video playout is started using the live version of the YouTube platform. Furthermore, we evaluate how different network parameters, i.e. bandwidth, RTTs and packet loss influence the different protocols. This work presents an verview over the characteristics of the compared protocols and presents a detailed measurement methodology on how the data has been obtained. Finally, the observed data is evaluated in the context of YouTube video streaming.
• Applicability and Limitations of a Simple WiFi Hotspot Model for Cities. Seufert, Michael; Moldovan, Christian; Burger, Valentin; Hoßfeld, Tobias. In 13th International Conference on Network and Service Management (CNSM). Tokio, Japan, 2017.
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  Offloading mobile Internet data via WiFi has emerged as an omnipresent trend. WiFi networks are already widely deployed by many private and public institutions (e.g., libraries, cafes, restaurants) but also by commercial services to provide alternative Internet access for their customers and to mitigate the load on mobile networks. Moreover, smart cities start to install WiFi infrastructure for current and future civic services, e.g., based on sensor networks or the Internet of Things. A simple model for the distribution of WiFi hotspots in an urban environment is presented. The hotspot locations are modeled with a uniform distribution of the angle and an exponential distribution of the distance, which is truncated to the city limits. We compare the characteristics of this model in detail to the real distributions. Moreover, we show the applicability and the limitations of this model, and the results suggest that the model can be used in scenarios, which do not require an accurate spatial collocation of the hotspots, such as offloading potential, coverage, or signal strength.

  @inproceedings{info3-inproceedings-2017-19, abstract = {Offloading mobile Internet data via WiFi has emerged as an omnipresent trend. WiFi networks are already widely deployed by many private and public institutions (e.g., libraries, cafes, restaurants) but also by commercial services to provide alternative Internet access for their customers and to mitigate the load on mobile networks. Moreover, smart cities start to install WiFi infrastructure for current and future civic services, e.g., based on sensor networks or the Internet of Things. A simple model for the distribution of WiFi hotspots in an urban environment is presented. The hotspot locations are modeled with a uniform distribution of the angle and an exponential distribution of the distance, which is truncated to the city limits. We compare the characteristics of this model in detail to the real distributions. Moreover, we show the applicability and the limitations of this model, and the results suggest that the model can be used in scenarios, which do not require an accurate spatial collocation of the hotspots, such as offloading potential, coverage, or signal strength.}, address = {Tokio, Japan}, author = {Seufert, Michael and Moldovan, Christian and Burger, Valentin and Hoßfeld, Tobias}, booktitle = {13th International Conference on Network and Service Management (CNSM)}, keywords = {can}, month = 11, title = {Applicability and Limitations of a Simple WiFi Hotspot Model for Cities}, year = 2017 }

  %0 Conference Paper %1 info3-inproceedings-2017-19 %A Seufert, Michael %A Moldovan, Christian %A Burger, Valentin %A Hoßfeld, Tobias %B 13th International Conference on Network and Service Management (CNSM) %C Tokio, Japan %D 2017 %T Applicability and Limitations of a Simple WiFi Hotspot Model for Cities %X Offloading mobile Internet data via WiFi has emerged as an omnipresent trend. WiFi networks are already widely deployed by many private and public institutions (e.g., libraries, cafes, restaurants) but also by commercial services to provide alternative Internet access for their customers and to mitigate the load on mobile networks. Moreover, smart cities start to install WiFi infrastructure for current and future civic services, e.g., based on sensor networks or the Internet of Things. A simple model for the distribution of WiFi hotspots in an urban environment is presented. The hotspot locations are modeled with a uniform distribution of the angle and an exponential distribution of the distance, which is truncated to the city limits. We compare the characteristics of this model in detail to the real distributions. Moreover, we show the applicability and the limitations of this model, and the results suggest that the model can be used in scenarios, which do not require an accurate spatial collocation of the hotspots, such as offloading potential, coverage, or signal strength.

• Load Dynamics of a Multiplayer Online Battle Area and Simulative Assessment of Edge Server Placements. Burger, Valentin; Frances Pajo, Jane; Sanchez, Odnan Ref; Seufert, Michael; Schwartz, Christian; Wamser, Florian; Davoli, Franco; Tran-Gia, Phuoc. In ACM Multimedia Systems Conference (MMSys). Klagenfurt, Austria, 2016.
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  Free-to-play models, streaming of games and eSports are reasons for online gaming to grow in popularity recently. On the forefront are multiplayer online battle arenas, which gain high popularity by introducing a competitive format that is easy to access and requires cooperation and team play. These games highly rely on fast reaction of the players, which makes latency the key performance indicator of such applications. To obtain low latency, this paper proposes moving game servers close to players towards the edge of the network. The performance of such mechanism highly depends on the geographic distribution of players. By analyzing match histories and statistics, we develop models for the arrival process and location of game requests. This allows us to evaluate the performance of edge server resource migration policies in an event based simulation. Our results show that a high number of edge servers is preferable compared to few larger edge servers to reduce the latency of players. This supports approaches that allow deploying virtual server instances in the back-haul.

  @inproceedings{info3-inproceedings-2016-2, abstract = {Free-to-play models, streaming of games and eSports are reasons for online gaming to grow in popularity recently. On the forefront are multiplayer online battle arenas, which gain high popularity by introducing a competitive format that is easy to access and requires cooperation and team play. These games highly rely on fast reaction of the players, which makes latency the key performance indicator of such applications. To obtain low latency, this paper proposes moving game servers close to players towards the edge of the network. The performance of such mechanism highly depends on the geographic distribution of players. By analyzing match histories and statistics, we develop models for the arrival process and location of game requests. This allows us to evaluate the performance of edge server resource migration policies in an event based simulation. Our results show that a high number of edge servers is preferable compared to few larger edge servers to reduce the latency of players. This supports approaches that allow deploying virtual server instances in the back-haul.}, address = {Klagenfurt, Austria}, author = {Burger, Valentin and Frances Pajo, Jane and Sanchez, Odnan Ref and Seufert, Michael and Schwartz, Christian and Wamser, Florian and Davoli, Franco and Tran-Gia, Phuoc}, booktitle = {ACM Multimedia Systems Conference (MMSys)}, keywords = {can}, month = {05}, title = {Load Dynamics of a Multiplayer Online Battle Area and Simulative Assessment of Edge Server Placements}, year = 2016 }

  %0 Conference Paper %1 info3-inproceedings-2016-2 %A Burger, Valentin %A Frances Pajo, Jane %A Sanchez, Odnan Ref %A Seufert, Michael %A Schwartz, Christian %A Wamser, Florian %A Davoli, Franco %A Tran-Gia, Phuoc %B ACM Multimedia Systems Conference (MMSys) %C Klagenfurt, Austria %D 2016 %T Load Dynamics of a Multiplayer Online Battle Area and Simulative Assessment of Edge Server Placements %X Free-to-play models, streaming of games and eSports are reasons for online gaming to grow in popularity recently. On the forefront are multiplayer online battle arenas, which gain high popularity by introducing a competitive format that is easy to access and requires cooperation and team play. These games highly rely on fast reaction of the players, which makes latency the key performance indicator of such applications. To obtain low latency, this paper proposes moving game servers close to players towards the edge of the network. The performance of such mechanism highly depends on the geographic distribution of players. By analyzing match histories and statistics, we develop models for the arrival process and location of game requests. This allows us to evaluate the performance of edge server resource migration policies in an event based simulation. Our results show that a high number of edge servers is preferable compared to few larger edge servers to reduce the latency of players. This supports approaches that allow deploying virtual server instances in the back-haul.
• A Simple WiFi Hotspot Model for Cities. Seufert, Michael; Griepentrog, Tobias; Burger, Valentin; Hoßfeld, Tobias. In IEEE Communications Letters, 20(2), pp. 384–387. 2016.
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  WiFi offloading has become increasingly popular. Many private and public institutions (e.g., libraries, cafes, restaurants) already provide an alternative free Internet link via WiFi, but also commercial services emerge to mitigate the load on mobile networks. Moreover, smart cities start to establish WiFi infrastructure for current and future civic services. In this work, the hotspot locations of ten diverse large cities are characterized, and a surprisingly simple model for the distribution of WiFi hotspots in an urban environment is derived.

  @article{info3-article-2016-2, abstract = {WiFi offloading has become increasingly popular. Many private and public institutions (e.g., libraries, cafes, restaurants) already provide an alternative free Internet link via WiFi, but also commercial services emerge to mitigate the load on mobile networks. Moreover, smart cities start to establish WiFi infrastructure for current and future civic services. In this work, the hotspot locations of ten diverse large cities are characterized, and a surprisingly simple model for the distribution of WiFi hotspots in an urban environment is derived.}, author = {Seufert, Michael and Griepentrog, Tobias and Burger, Valentin and Hoßfeld, Tobias}, journal = {IEEE Communications Letters}, keywords = {can}, month = {02}, number = 2, pages = {384 - 387}, title = {A Simple WiFi Hotspot Model for Cities}, volume = 20, year = 2016 }

  %0 Journal Article %1 info3-article-2016-2 %A Seufert, Michael %A Griepentrog, Tobias %A Burger, Valentin %A Hoßfeld, Tobias %D 2016 %J IEEE Communications Letters %N 2 %P 384 - 387 %T A Simple WiFi Hotspot Model for Cities %V 20 %X WiFi offloading has become increasingly popular. Many private and public institutions (e.g., libraries, cafes, restaurants) already provide an alternative free Internet link via WiFi, but also commercial services emerge to mitigate the load on mobile networks. Moreover, smart cities start to establish WiFi infrastructure for current and future civic services. In this work, the hotspot locations of ten diverse large cities are characterized, and a surprisingly simple model for the distribution of WiFi hotspots in an urban environment is derived.
• Group-based Communication in WhatsApp. Seufert, Michael; Hoßfeld, Tobias; Schwind, Anika; Burger, Valentin; Tran-Gia, Phuoc. In 1st IFIP Internet of People Workshop (IoP). Vienna, Austria, 2016.
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  WhatsApp is a very popular mobile messaging application, which dominates today’s mobile communication. Especially the feature of group chats contributes to its success and changes the way people communicate. The group-based communication paradigm is investigated in this work, particularly focusing on the usage of WhatsApp, communication in group chats, and implications on mobile network traffic.

  @inproceedings{info3-inproceedings-2016-1, abstract = {WhatsApp is a very popular mobile messaging application, which dominates today’s mobile communication. Especially the feature of group chats contributes to its success and changes the way people communicate. The group-based communication paradigm is investigated in this work, particularly focusing on the usage of WhatsApp, communication in group chats, and implications on mobile network traffic.}, address = {Vienna, Austria}, author = {Seufert, Michael and Hoßfeld, Tobias and Schwind, Anika and Burger, Valentin and Tran-Gia, Phuoc}, booktitle = {1st IFIP Internet of People Workshop (IoP)}, keywords = {can}, month = {05}, title = {Group-based Communication in WhatsApp}, year = 2016 }

  %0 Conference Paper %1 info3-inproceedings-2016-1 %A Seufert, Michael %A Hoßfeld, Tobias %A Schwind, Anika %A Burger, Valentin %A Tran-Gia, Phuoc %B 1st IFIP Internet of People Workshop (IoP) %C Vienna, Austria %D 2016 %T Group-based Communication in WhatsApp %X WhatsApp is a very popular mobile messaging application, which dominates today’s mobile communication. Especially the feature of group chats contributes to its success and changes the way people communicate. The group-based communication paradigm is investigated in this work, particularly focusing on the usage of WhatsApp, communication in group chats, and implications on mobile network traffic.
• Assessment of Subjective Influence and Trust with an Online Social Network Game. Seufert, Michael; Burger, Valentin; Lorey, Karl; Seith, Alexander; Loh, Frank; Tran-Gia, Phuoc. In Computers in Human Behavior, 64, pp. 233–246. 2016.
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  The deduction of influence and trust between two individuals only from objective data in online social networks (OSNs) is a rather vague approach. Subjective assessments via surveys produce better results, but are harder to conduct considering the vast amount of friendships of OSN users. This work presents a framework for personalized surveys on relationships in OSNs, which follows a gamification approach. A Facebook game was developed, which was used to subjectively assess social influence and interpersonal trust based on models from psychology. The results show that it is possible to obtain subjective opinions and (limited) objective data about relationships with an OSN game. Also an implicit assessment of influence and trust with subcategory questions is feasible in this case.

  @article{info3-article-2016-7, abstract = {The deduction of influence and trust between two individuals only from objective data in online social networks (OSNs) is a rather vague approach. Subjective assessments via surveys produce better results, but are harder to conduct considering the vast amount of friendships of OSN users. This work presents a framework for personalized surveys on relationships in OSNs, which follows a gamification approach. A Facebook game was developed, which was used to subjectively assess social influence and interpersonal trust based on models from psychology. The results show that it is possible to obtain subjective opinions and (limited) objective data about relationships with an OSN game. Also an implicit assessment of influence and trust with subcategory questions is feasible in this case.}, author = {Seufert, Michael and Burger, Valentin and Lorey, Karl and Seith, Alexander and Loh, Frank and Tran-Gia, Phuoc}, journal = {Computers in Human Behavior}, keywords = {can}, month = 11, pages = {233-246}, title = {Assessment of Subjective Influence and Trust with an Online Social Network Game}, volume = 64, year = 2016 }

  %0 Journal Article %1 info3-article-2016-7 %A Seufert, Michael %A Burger, Valentin %A Lorey, Karl %A Seith, Alexander %A Loh, Frank %A Tran-Gia, Phuoc %D 2016 %J Computers in Human Behavior %P 233-246 %T Assessment of Subjective Influence and Trust with an Online Social Network Game %V 64 %X The deduction of influence and trust between two individuals only from objective data in online social networks (OSNs) is a rather vague approach. Subjective assessments via surveys produce better results, but are harder to conduct considering the vast amount of friendships of OSN users. This work presents a framework for personalized surveys on relationships in OSNs, which follows a gamification approach. A Facebook game was developed, which was used to subjectively assess social influence and interpersonal trust based on models from psychology. The results show that it is possible to obtain subjective opinions and (limited) objective data about relationships with an OSN game. Also an implicit assessment of influence and trust with subcategory questions is feasible in this case.
• Performance Evaluation of Backhaul Bandwidth Aggregation Using a Partial Sharing Scheme. Burger, Valentin; Seufert, Michael; Hoßfeld, Tobias; Tran-Gia, Phuoc. In Physical Communication, 19, pp. 135–144. 2016.
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  To cope with the increasing demand of mobile devices and the limited capacity of cellular networks mobile connections are offloaded to WiFi. The access capacity is further increased, by aggregating bandwidth of WiFi access links. To analyse the performance of aggregated access links we model the most simple case of two cooperating systems interchanging capacities using an offloading scheme. The resulting analytic model is computed by means of a two-dimensional birth and death process. It can be used to seamlessly evaluate the performance of systems between partitioning and complete sharing. This allows to optimize the setting of thresholds dependent on the load of the cooperating system. Furthermore the benefit of aggregating bandwidth in different scenarios with homogeneous and heterogeneous workloads is quantified and the performance of more than two cooperating systems is evaluated by simulation.

  @article{info3-article-2016-3, abstract = {To cope with the increasing demand of mobile devices and the limited capacity of cellular networks mobile connections are offloaded to WiFi. The access capacity is further increased, by aggregating bandwidth of WiFi access links. To analyse the performance of aggregated access links we model the most simple case of two cooperating systems interchanging capacities using an offloading scheme. The resulting analytic model is computed by means of a two-dimensional birth and death process. It can be used to seamlessly evaluate the performance of systems between partitioning and complete sharing. This allows to optimize the setting of thresholds dependent on the load of the cooperating system. Furthermore the benefit of aggregating bandwidth in different scenarios with homogeneous and heterogeneous workloads is quantified and the performance of more than two cooperating systems is evaluated by simulation.}, author = {Burger, Valentin and Seufert, Michael and Hoßfeld, Tobias and Tran-Gia, Phuoc}, journal = {Physical Communication}, keywords = {can}, month = {06}, pages = {135-144}, title = {Performance Evaluation of Backhaul Bandwidth Aggregation Using a Partial Sharing Scheme}, volume = 19, year = 2016 }

  %0 Journal Article %1 info3-article-2016-3 %A Burger, Valentin %A Seufert, Michael %A Hoßfeld, Tobias %A Tran-Gia, Phuoc %D 2016 %J Physical Communication %P 135-144 %T Performance Evaluation of Backhaul Bandwidth Aggregation Using a Partial Sharing Scheme %V 19 %X To cope with the increasing demand of mobile devices and the limited capacity of cellular networks mobile connections are offloaded to WiFi. The access capacity is further increased, by aggregating bandwidth of WiFi access links. To analyse the performance of aggregated access links we model the most simple case of two cooperating systems interchanging capacities using an offloading scheme. The resulting analytic model is computed by means of a two-dimensional birth and death process. It can be used to seamlessly evaluate the performance of systems between partitioning and complete sharing. This allows to optimize the setting of thresholds dependent on the load of the cooperating system. Furthermore the benefit of aggregating bandwidth in different scenarios with homogeneous and heterogeneous workloads is quantified and the performance of more than two cooperating systems is evaluated by simulation.
• Principles of Information Neutrality and Counter Measures Against Biased Information. Burger, Valentin; Hirth, Matthias; Hoßfeld, Tobias; Tran-Gia, Phuoc. In Lecture Notes in Informatics: Value-Sensitive Design of Internet-Based Services. Klagenfurt, Austria, 2016.
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  The Internet serves as ubiquitous, prompt source of information in our society. Due to the giant amount of information, the access to the information relies on information processing mechanisms as implemented in search engines, product recommendation systems, or online social networks. As a result of the engineered preprocessing mechanism, the retrieved information is biased and does not represent a neutral view on the available information, while end-users often are not aware of this bias. In this article, we define the term “Information Neutrality”, review current principles of information processing in the Internet and discuss influence factors hindering Information Neutrality as well as appropriate countermeasures. The main contribution of this article is to raise the awareness of Information Neutrality as an emerging key challenge in the Internet and to potentially consider Information Neutrality as a factor in the value-sensitive design of Internet-based services.

  @inproceedings{info3-inproceedings-2016-21, abstract = {The Internet serves as ubiquitous, prompt source of information in our society. Due to the giant amount of information, the access to the information relies on information processing mechanisms as implemented in search engines, product recommendation systems, or online social networks. As a result of the engineered preprocessing mechanism, the retrieved information is biased and does not represent a neutral view on the available information, while end-users often are not aware of this bias. In this article, we define the term “Information Neutrality”, review current principles of information processing in the Internet and discuss influence factors hindering Information Neutrality as well as appropriate countermeasures. The main contribution of this article is to raise the awareness of Information Neutrality as an emerging key challenge in the Internet and to potentially consider Information Neutrality as a factor in the value-sensitive design of Internet-based services.}, address = {Klagenfurt, Austria}, author = {Burger, Valentin and Hirth, Matthias and Hoßfeld, Tobias and Tran-Gia, Phuoc}, booktitle = {Lecture Notes in Informatics: Value-Sensitive Design of Internet-Based Services}, keywords = {sys:hidden:inproceedings}, month = {09}, title = {Principles of Information Neutrality and Counter Measures Against Biased Information}, year = 2016 }

  %0 Conference Paper %1 info3-inproceedings-2016-21 %A Burger, Valentin %A Hirth, Matthias %A Hoßfeld, Tobias %A Tran-Gia, Phuoc %B Lecture Notes in Informatics: Value-Sensitive Design of Internet-Based Services %C Klagenfurt, Austria %D 2016 %T Principles of Information Neutrality and Counter Measures Against Biased Information %X The Internet serves as ubiquitous, prompt source of information in our society. Due to the giant amount of information, the access to the information relies on information processing mechanisms as implemented in search engines, product recommendation systems, or online social networks. As a result of the engineered preprocessing mechanism, the retrieved information is biased and does not represent a neutral view on the available information, while end-users often are not aware of this bias. In this article, we define the term “Information Neutrality”, review current principles of information processing in the Internet and discuss influence factors hindering Information Neutrality as well as appropriate countermeasures. The main contribution of this article is to raise the awareness of Information Neutrality as an emerging key challenge in the Internet and to potentially consider Information Neutrality as a factor in the value-sensitive design of Internet-based services.
• Evaluating the Impact of WiFi Offloading on Mobile Users of HTTP Adaptive Video Streaming. Seufert, Michael; Burger, Valentin; Kaup, Fabian. In 5th IEEE International Workshop on Quality of Experience for Multimedia Communications (QoEMC). Washington, DC, USA, 2016.
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  In a recent trend to lessen the load on cellular networks in cities, users are offered to offload mobile connections to lower cost WiFi networks. In this work, we conduct a simulative performance evaluation of the impact of WiFi offloading for a mobile end user of a HTTP adaptive video streaming (HAS) service depending on availability and range of the WiFi hotspots. The simulation is based on connectivity measurements from a German city and evaluates the key performance indicators for the QoE of HAS, i.e., initial delay, stalling, and quality adaptation. Additionally, a smartphone energy model is applied to assess the energy consumption during the streaming. The results indicate that WiFi offloading of HAS connections to public WiFi hotspots is not attractive for end users both in terms of QoE and energy consumption. However, it can be shown that WiFi offloading can be beneficial also for end users in case high bandwidths can be received via WiFi.

  @inproceedings{info3-inproceedings-2016-18, abstract = {In a recent trend to lessen the load on cellular networks in cities, users are offered to offload mobile connections to lower cost WiFi networks. In this work, we conduct a simulative performance evaluation of the impact of WiFi offloading for a mobile end user of a HTTP adaptive video streaming (HAS) service depending on availability and range of the WiFi hotspots. The simulation is based on connectivity measurements from a German city and evaluates the key performance indicators for the QoE of HAS, i.e., initial delay, stalling, and quality adaptation. Additionally, a smartphone energy model is applied to assess the energy consumption during the streaming. The results indicate that WiFi offloading of HAS connections to public WiFi hotspots is not attractive for end users both in terms of QoE and energy consumption. However, it can be shown that WiFi offloading can be beneficial also for end users in case high bandwidths can be received via WiFi.}, address = {Washington, DC, USA}, author = {Seufert, Michael and Burger, Valentin and Kaup, Fabian}, booktitle = {5th IEEE International Workshop on Quality of Experience for Multimedia Communications (QoEMC)}, keywords = {can}, month = 12, title = {Evaluating the Impact of WiFi Offloading on Mobile Users of HTTP Adaptive Video Streaming}, year = 2016 }

  %0 Conference Paper %1 info3-inproceedings-2016-18 %A Seufert, Michael %A Burger, Valentin %A Kaup, Fabian %B 5th IEEE International Workshop on Quality of Experience for Multimedia Communications (QoEMC) %C Washington, DC, USA %D 2016 %T Evaluating the Impact of WiFi Offloading on Mobile Users of HTTP Adaptive Video Streaming %X In a recent trend to lessen the load on cellular networks in cities, users are offered to offload mobile connections to lower cost WiFi networks. In this work, we conduct a simulative performance evaluation of the impact of WiFi offloading for a mobile end user of a HTTP adaptive video streaming (HAS) service depending on availability and range of the WiFi hotspots. The simulation is based on connectivity measurements from a German city and evaluates the key performance indicators for the QoE of HAS, i.e., initial delay, stalling, and quality adaptation. Additionally, a smartphone energy model is applied to assess the energy consumption during the streaming. The results indicate that WiFi offloading of HAS connections to public WiFi hotspots is not attractive for end users both in terms of QoE and energy consumption. However, it can be shown that WiFi offloading can be beneficial also for end users in case high bandwidths can be received via WiFi.
• Performance Analysis of Hierarchical Caching Systems with Bandwidth Constraints. Burger, Valentin; Zinner, Thomas. In Proceedings of the International Telecommunication Networks and Applications Conference. Dunedin, New Zealand, 2016.
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  The vast majority of Internet traffic is carried by content delivery networks. A high potential to bring content even closer to consumers and to reduce energy cost is achieved by the nano data center (NaDa) concept that has been proposed in recent work. In this approach the capacity available on small devices such as home gateways is used to support content delivery in an hierarchical caching system. In this work, we present a method to determine the efficiency of hierarchical content delivery networks with limited bandwidth, such as in the NaDa approach, analytically. We analyze the Internet Census Dataset to assess the number of available devices on autonomous system level. We evaluate the potential of hierarchical cache networks with bandwidth constraints to assist content delivery and determine its limits.

  @inproceedings{info3-inproceedings-2016-22, abstract = {The vast majority of Internet traffic is carried by content delivery networks. A high potential to bring content even closer to consumers and to reduce energy cost is achieved by the nano data center (NaDa) concept that has been proposed in recent work. In this approach the capacity available on small devices such as home gateways is used to support content delivery in an hierarchical caching system. In this work, we present a method to determine the efficiency of hierarchical content delivery networks with limited bandwidth, such as in the NaDa approach, analytically. We analyze the Internet Census Dataset to assess the number of available devices on autonomous system level. We evaluate the potential of hierarchical cache networks with bandwidth constraints to assist content delivery and determine its limits.}, address = {Dunedin, New Zealand}, author = {Burger, Valentin and Zinner, Thomas}, booktitle = {Proceedings of the International Telecommunication Networks and Applications Conference}, keywords = {can}, month = 12, title = {Performance Analysis of Hierarchical Caching Systems with Bandwidth Constraints}, year = 2016 }

  %0 Conference Paper %1 info3-inproceedings-2016-22 %A Burger, Valentin %A Zinner, Thomas %B Proceedings of the International Telecommunication Networks and Applications Conference %C Dunedin, New Zealand %D 2016 %T Performance Analysis of Hierarchical Caching Systems with Bandwidth Constraints %X The vast majority of Internet traffic is carried by content delivery networks. A high potential to bring content even closer to consumers and to reduce energy cost is achieved by the nano data center (NaDa) concept that has been proposed in recent work. In this approach the capacity available on small devices such as home gateways is used to support content delivery in an hierarchical caching system. In this work, we present a method to determine the efficiency of hierarchical content delivery networks with limited bandwidth, such as in the NaDa approach, analytically. We analyze the Internet Census Dataset to assess the number of available devices on autonomous system level. We evaluate the potential of hierarchical cache networks with bandwidth constraints to assist content delivery and determine its limits.

• Energy Considerations for WiFi Offloading of Video Streaming. Burger, Valentin; Kaup, Fabian; Seufert, Michael; Wichtlhuber, Matthias; Hausheer, David; Tran-Gia, Phuoc. In 7th EAI International Conference on Mobile Networks and Management (MONAMI). Santander, Spain, 2015.
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  The load on cellular networks is constantly increasing. Especially video streaming applications, whose demands and requirements keep growing, put high loads on cellular networks. A solution to mitigate the cellular load in urban environments is offloading mobile connections to WiFi access points, which is followed by many providers recently. Because of the large number of mobile users and devices there is also a high potential to save energy by WiFi offloading. In this work, we develop a model to assess the energy consumption of mobile devices during video sessions. We evaluate the potential of WiFi offloading in an urban environment and the implications of offloading connections on energy consumption of mobile devices. Our results show that, although WiFi is more energy efficient than 3G and 4G for equal data rates, the energy consumption increases with the amount of connections offloaded to WiFi, due to poor data rates obtained for WiFi in the streets. This suggests further deployment of WiFi access points or WiFi sharing incentives to increase data rates for WiFi and energy efficiency of mobile access.

  @inproceedings{info3-inproceedings-2015-524, abstract = {The load on cellular networks is constantly increasing. Especially video streaming applications, whose demands and requirements keep growing, put high loads on cellular networks. A solution to mitigate the cellular load in urban environments is offloading mobile connections to WiFi access points, which is followed by many providers recently. Because of the large number of mobile users and devices there is also a high potential to save energy by WiFi offloading. In this work, we develop a model to assess the energy consumption of mobile devices during video sessions. We evaluate the potential of WiFi offloading in an urban environment and the implications of offloading connections on energy consumption of mobile devices. Our results show that, although WiFi is more energy efficient than 3G and 4G for equal data rates, the energy consumption increases with the amount of connections offloaded to WiFi, due to poor data rates obtained for WiFi in the streets. This suggests further deployment of WiFi access points or WiFi sharing incentives to increase data rates for WiFi and energy efficiency of mobile access.}, address = {Santander, Spain}, author = {Burger, Valentin and Kaup, Fabian and Seufert, Michael and Wichtlhuber, Matthias and Hausheer, David and Tran-Gia, Phuoc}, booktitle = {7th EAI International Conference on Mobile Networks and Management (MONAMI)}, keywords = {smartenit}, month = {09}, title = {Energy Considerations for WiFi Offloading of Video Streaming}, year = 2015 }

  %0 Conference Paper %1 info3-inproceedings-2015-524 %A Burger, Valentin %A Kaup, Fabian %A Seufert, Michael %A Wichtlhuber, Matthias %A Hausheer, David %A Tran-Gia, Phuoc %B 7th EAI International Conference on Mobile Networks and Management (MONAMI) %C Santander, Spain %D 2015 %T Energy Considerations for WiFi Offloading of Video Streaming %X The load on cellular networks is constantly increasing. Especially video streaming applications, whose demands and requirements keep growing, put high loads on cellular networks. A solution to mitigate the cellular load in urban environments is offloading mobile connections to WiFi access points, which is followed by many providers recently. Because of the large number of mobile users and devices there is also a high potential to save energy by WiFi offloading. In this work, we develop a model to assess the energy consumption of mobile devices during video sessions. We evaluate the potential of WiFi offloading in an urban environment and the implications of offloading connections on energy consumption of mobile devices. Our results show that, although WiFi is more energy efficient than 3G and 4G for equal data rates, the energy consumption increases with the amount of connections offloaded to WiFi, due to poor data rates obtained for WiFi in the streets. This suggests further deployment of WiFi access points or WiFi sharing incentives to increase data rates for WiFi and energy efficiency of mobile access.
• Utilizing Home Router Caches to Augment CDNs towards Information-Centric Networking. Seufert, Michael; Burger, Valentin; Wamser, Florian; Tran-Gia, Phuoc; Moldovan, Christian; Hoßfeld, Tobias. In European Conference on Networks and Communications (EuCNC). Paris, France, 2015.
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  To implement improved Quality of Service (QoS) and Quality of Experience (QoE) management for content-heavy services like video streaming, content has to be moved closer to the edge. The concept of information-centric networking (ICN) would be a prospective enabler but is currently not practically feasible yet. We propose a hierarchical caching architecture utilizing caches on home routers to augment existing content delivery network (CDN) infrastructure. This approach can be implemented via Software-defined Networking (SDN) and brings current CDNs closer towards ICN. Based on a simulation study, we confirm that our approach is able to serve content more locally, which results in QoS and QoE benefits for end users as well as inter-domain traffic savings for network operators.

  @inproceedings{info3-inproceedings-2015-514, abstract = {To implement improved Quality of Service (QoS) and Quality of Experience (QoE) management for content-heavy services like video streaming, content has to be moved closer to the edge. The concept of information-centric networking (ICN) would be a prospective enabler but is currently not practically feasible yet. We propose a hierarchical caching architecture utilizing caches on home routers to augment existing content delivery network (CDN) infrastructure. This approach can be implemented via Software-defined Networking (SDN) and brings current CDNs closer towards ICN. Based on a simulation study, we confirm that our approach is able to serve content more locally, which results in QoS and QoE benefits for end users as well as inter-domain traffic savings for network operators.}, address = {Paris, France}, author = {Seufert, Michael and Burger, Valentin and Wamser, Florian and Tran-Gia, Phuoc and Moldovan, Christian and Hoßfeld, Tobias}, booktitle = {European Conference on Networks and Communications (EuCNC)}, keywords = {can}, month = {06}, title = {Utilizing Home Router Caches to Augment CDNs towards Information-Centric Networking}, year = 2015 }

  %0 Conference Paper %1 info3-inproceedings-2015-514 %A Seufert, Michael %A Burger, Valentin %A Wamser, Florian %A Tran-Gia, Phuoc %A Moldovan, Christian %A Hoßfeld, Tobias %B European Conference on Networks and Communications (EuCNC) %C Paris, France %D 2015 %T Utilizing Home Router Caches to Augment CDNs towards Information-Centric Networking %X To implement improved Quality of Service (QoS) and Quality of Experience (QoE) management for content-heavy services like video streaming, content has to be moved closer to the edge. The concept of information-centric networking (ICN) would be a prospective enabler but is currently not practically feasible yet. We propose a hierarchical caching architecture utilizing caches on home routers to augment existing content delivery network (CDN) infrastructure. This approach can be implemented via Software-defined Networking (SDN) and brings current CDNs closer towards ICN. Based on a simulation study, we confirm that our approach is able to serve content more locally, which results in QoS and QoE benefits for end users as well as inter-domain traffic savings for network operators.
• Impact of WiFi Offloading on Video Streaming QoE in Urban Environments. Burger, Valentin; Seufert, Michael; Kaup, Fabian; Wichtlhuber, Matthias; Hausheer, David; Tran-Gia, Phuoc. In IEEE Workshop on Quality of Experience-based Management for Future Internet Applications and Services (QoE-FI). London, UK, 2015.
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  Video streaming is the most popular application in today's mobile Internet and its growing demands and popularity put more and more load on cellular networks. In a recent trend to mitigate the cellular load, followed by many providers, users are offered to offload mobile connections to WiFi hotspots, which are predominately deployed in urban environments. In this work, we conduct a simulative performance evaluation of the impact of WiFi offloading on the Quality of Experience (QoE) of video streaming. The evaluation is based on connectivity measurements from a German city and uses a simple QoE model for estimating the perceived quality of video streaming. Our findings show that, despite its benefits for operators, offloading to WiFi has a negative impact on video streaming QoE for some users when 3G/4G coverage is available. Only in the case of 2G coverage, WiFi offloading can significantly improve the perceived quality for users.

  @inproceedings{info3-inproceedings-2015-511, abstract = {Video streaming is the most popular application in today's mobile Internet and its growing demands and popularity put more and more load on cellular networks. In a recent trend to mitigate the cellular load, followed by many providers, users are offered to offload mobile connections to WiFi hotspots, which are predominately deployed in urban environments. In this work, we conduct a simulative performance evaluation of the impact of WiFi offloading on the Quality of Experience (QoE) of video streaming. The evaluation is based on connectivity measurements from a German city and uses a simple QoE model for estimating the perceived quality of video streaming. Our findings show that, despite its benefits for operators, offloading to WiFi has a negative impact on video streaming QoE for some users when 3G/4G coverage is available. Only in the case of 2G coverage, WiFi offloading can significantly improve the perceived quality for users.}, address = {London, UK}, author = {Burger, Valentin and Seufert, Michael and Kaup, Fabian and Wichtlhuber, Matthias and Hausheer, David and Tran-Gia, Phuoc}, booktitle = {IEEE Workshop on Quality of Experience-based Management for Future Internet Applications and Services (QoE-FI)}, keywords = {smartenit}, month = {06}, title = {Impact of WiFi Offloading on Video Streaming QoE in Urban Environments}, year = 2015 }

  %0 Conference Paper %1 info3-inproceedings-2015-511 %A Burger, Valentin %A Seufert, Michael %A Kaup, Fabian %A Wichtlhuber, Matthias %A Hausheer, David %A Tran-Gia, Phuoc %B IEEE Workshop on Quality of Experience-based Management for Future Internet Applications and Services (QoE-FI) %C London, UK %D 2015 %T Impact of WiFi Offloading on Video Streaming QoE in Urban Environments %X Video streaming is the most popular application in today's mobile Internet and its growing demands and popularity put more and more load on cellular networks. In a recent trend to mitigate the cellular load, followed by many providers, users are offered to offload mobile connections to WiFi hotspots, which are predominately deployed in urban environments. In this work, we conduct a simulative performance evaluation of the impact of WiFi offloading on the Quality of Experience (QoE) of video streaming. The evaluation is based on connectivity measurements from a German city and uses a simple QoE model for estimating the perceived quality of video streaming. Our findings show that, despite its benefits for operators, offloading to WiFi has a negative impact on video streaming QoE for some users when 3G/4G coverage is available. Only in the case of 2G coverage, WiFi offloading can significantly improve the perceived quality for users.
• WiFi Offloading and Socially Aware Prefetching on Augmented Home Routers. Petropoulos, George; Lareida, Andri; Soursos, Sergios; Seufert, Michael; Burger, Valentin; Stiller, Burkhard. Clearwater Beach, FL, USA, 2015, October.
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  @misc{info3-software-2015-25, address = {Clearwater Beach, FL, USA}, author = {Petropoulos, George and Lareida, Andri and Soursos, Sergios and Seufert, Michael and Burger, Valentin and Stiller, Burkhard}, booktitle = {40th Annual IEEE Conference on Local Computer Networks (LCN), Best Demo Award}, keywords = {sys:hidden:software}, month = 10, title = {WiFi Offloading and Socially Aware Prefetching on Augmented Home Routers}, year = 2015 }

  %0 Generic %1 info3-software-2015-25 %A Petropoulos, George %A Lareida, Andri %A Soursos, Sergios %A Seufert, Michael %A Burger, Valentin %A Stiller, Burkhard %B 40th Annual IEEE Conference on Local Computer Networks (LCN), Best Demo Award %C Clearwater Beach, FL, USA %D 2015 %T WiFi Offloading and Socially Aware Prefetching on Augmented Home Routers
• Utilizing Backhaul Capacities to Meet the Mobile Data Challenge. Burger, Valentin; Seufert, Michael; Tran-Gia, Phuoc. Joint ITG 5.2.1/5.2.4 Workshop on Cloud Networking, Tübingen, Germany, 2015, September 24.
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  @presentation{info3-talk-2015-495, address = {Joint ITG 5.2.1/5.2.4 Workshop on Cloud Networking, Tübingen, Germany}, author = {Burger, Valentin and Seufert, Michael and Tran-Gia, Phuoc}, keywords = {sys:hidden:presentation}, month = {09}, title = {Utilizing Backhaul Capacities to Meet the Mobile Data Challenge}, year = 2015 }

  %0 Generic %1 info3-talk-2015-495 %A Burger, Valentin %A Seufert, Michael %A Tran-Gia, Phuoc %C Joint ITG 5.2.1/5.2.4 Workshop on Cloud Networking, Tübingen, Germany %D 2015 %T Utilizing Backhaul Capacities to Meet the Mobile Data Challenge
• Trade-Off between QoE and Operational Cost in Edge Resource Supported Video Streaming. Burger, Valentin; Darzanos, George; Papafili, Ioanna; Seufert, Michael. In 10th International Conference on P2P, Parallel, Grid, Cloud and Internet Computing (3PGCIC). Krakow, Poland, 2015.
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  The largest share of today`s consumer Internet traffic is video streaming and its demand on content delivery networks is continuously growing. To cope with the increasing demand of video streaming, recent work proposes mitigating end-user equipment to support content delivery at the edge of the network. The throughput of end-user equipment supporting content delivery is limited by the uplink of the users Internet connection.Especially for video streaming insufficient throughput causes the video to stall and affects the Quality of Experience (QoE) of end-users.To prevent video streams from stalling, we consider a tiered caching architecture, which requests higher tier caches to support content delivery, if the uplink throughput drops below a certain threshold. We conduct a simulative performance evaluation of the mechanism to investigate its impact on the QoE of end-users. Our results show that especially if the upload bandwidth of end-user equipment is low the setting of the threshold has a high impact. This can be used by operators to achieve the desired trade-off between QoE and operational cost for cache resources.

  @inproceedings{info3-inproceedings-2015-530, abstract = {The largest share of today`s consumer Internet traffic is video streaming and its demand on content delivery networks is continuously growing. To cope with the increasing demand of video streaming, recent work proposes mitigating end-user equipment to support content delivery at the edge of the network. The throughput of end-user equipment supporting content delivery is limited by the uplink of the users Internet connection.Especially for video streaming insufficient throughput causes the video to stall and affects the Quality of Experience (QoE) of end-users.To prevent video streams from stalling, we consider a tiered caching architecture, which requests higher tier caches to support content delivery, if the uplink throughput drops below a certain threshold. We conduct a simulative performance evaluation of the mechanism to investigate its impact on the QoE of end-users. Our results show that especially if the upload bandwidth of end-user equipment is low the setting of the threshold has a high impact. This can be used by operators to achieve the desired trade-off between QoE and operational cost for cache resources.}, address = {Krakow, Poland}, author = {Burger, Valentin and Darzanos, George and Papafili, Ioanna and Seufert, Michael}, booktitle = {10th International Conference on P2P, Parallel, Grid, Cloud and Internet Computing (3PGCIC)}, keywords = {can}, month = 11, title = {Trade-Off between QoE and Operational Cost in Edge Resource Supported Video Streaming}, year = 2015 }

  %0 Conference Paper %1 info3-inproceedings-2015-530 %A Burger, Valentin %A Darzanos, George %A Papafili, Ioanna %A Seufert, Michael %B 10th International Conference on P2P, Parallel, Grid, Cloud and Internet Computing (3PGCIC) %C Krakow, Poland %D 2015 %T Trade-Off between QoE and Operational Cost in Edge Resource Supported Video Streaming %X The largest share of today`s consumer Internet traffic is video streaming and its demand on content delivery networks is continuously growing. To cope with the increasing demand of video streaming, recent work proposes mitigating end-user equipment to support content delivery at the edge of the network. The throughput of end-user equipment supporting content delivery is limited by the uplink of the users Internet connection.Especially for video streaming insufficient throughput causes the video to stall and affects the Quality of Experience (QoE) of end-users.To prevent video streams from stalling, we consider a tiered caching architecture, which requests higher tier caches to support content delivery, if the uplink throughput drops below a certain threshold. We conduct a simulative performance evaluation of the mechanism to investigate its impact on the QoE of end-users. Our results show that especially if the upload bandwidth of end-user equipment is low the setting of the threshold has a high impact. This can be used by operators to achieve the desired trade-off between QoE and operational cost for cache resources.
• Augmenting Home Routers for Socially-Aware Traffic Management. Lareida, Andri; Petropoulos, George; Burger, Valentin; Seufert, Michael; Soursos, Sergios; Stiller, Burkhard. In 40th Annual IEEE Conference on Local Computer Networks (LCN). Clearwater Beach, FL, USA, 2015.
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  Mobile users' Quality-of-Experience (QoE) is degrading as network usage increases while Internet Service Providers (ISP) face increased inter-domain traffic. This paper presents a network traffic management mechanism, named RB-HORST, addressing these inefficiencies. RB-HORST exploits home routers by using them as caches and forming an overlay network between them to transfer content. To shift traffic from peak hours, RB-HORST employs predictions based on social network properties and based on similarity in the overlay network. To further improve user QoE, home routers allow trusted mobile devices to offload their mobile connection to the local WiFi. Simulation results show that an overlay is imperative for the success of the proposed caching mechanism. Especially ISPs with a large number of customers can benefit if only every thousandth user shares its router, reducing inter-domain traffic by half and superseding an ISP operated cache. The presented implementation proves that the concept is technically feasible and can be deployed and run on constrained devices.

  @inproceedings{info3-inproceedings-2015-518, abstract = {Mobile users' Quality-of-Experience (QoE) is degrading as network usage increases while Internet Service Providers (ISP) face increased inter-domain traffic. This paper presents a network traffic management mechanism, named RB-HORST, addressing these inefficiencies. RB-HORST exploits home routers by using them as caches and forming an overlay network between them to transfer content. To shift traffic from peak hours, RB-HORST employs predictions based on social network properties and based on similarity in the overlay network. To further improve user QoE, home routers allow trusted mobile devices to offload their mobile connection to the local WiFi. Simulation results show that an overlay is imperative for the success of the proposed caching mechanism. Especially ISPs with a large number of customers can benefit if only every thousandth user shares its router, reducing inter-domain traffic by half and superseding an ISP operated cache. The presented implementation proves that the concept is technically feasible and can be deployed and run on constrained devices.}, address = {Clearwater Beach, FL, USA}, author = {Lareida, Andri and Petropoulos, George and Burger, Valentin and Seufert, Michael and Soursos, Sergios and Stiller, Burkhard}, booktitle = {40th Annual IEEE Conference on Local Computer Networks (LCN)}, keywords = {smartenit}, month = 10, title = {Augmenting Home Routers for Socially-Aware Traffic Management}, year = 2015 }

  %0 Conference Paper %1 info3-inproceedings-2015-518 %A Lareida, Andri %A Petropoulos, George %A Burger, Valentin %A Seufert, Michael %A Soursos, Sergios %A Stiller, Burkhard %B 40th Annual IEEE Conference on Local Computer Networks (LCN) %C Clearwater Beach, FL, USA %D 2015 %T Augmenting Home Routers for Socially-Aware Traffic Management %X Mobile users' Quality-of-Experience (QoE) is degrading as network usage increases while Internet Service Providers (ISP) face increased inter-domain traffic. This paper presents a network traffic management mechanism, named RB-HORST, addressing these inefficiencies. RB-HORST exploits home routers by using them as caches and forming an overlay network between them to transfer content. To shift traffic from peak hours, RB-HORST employs predictions based on social network properties and based on similarity in the overlay network. To further improve user QoE, home routers allow trusted mobile devices to offload their mobile connection to the local WiFi. Simulation results show that an overlay is imperative for the success of the proposed caching mechanism. Especially ISPs with a large number of customers can benefit if only every thousandth user shares its router, reducing inter-domain traffic by half and superseding an ISP operated cache. The presented implementation proves that the concept is technically feasible and can be deployed and run on constrained devices.

• Ambient Assisted Living. Zinner, Thomas; Burger, Valentin. Datev Trendscout, Nürnberg, Germany, 2014, November 27.
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  @presentation{info3-talk-2014-490, address = {Datev Trendscout, Nürnberg, Germany}, author = {Zinner, Thomas and Burger, Valentin}, keywords = {sys:hidden:presentation}, month = 11, title = {Ambient Assisted Living}, year = 2014 }

  %0 Generic %1 info3-talk-2014-490 %A Zinner, Thomas %A Burger, Valentin %C Datev Trendscout, Nürnberg, Germany %D 2014 %T Ambient Assisted Living
• Socially-Aware Traffic Management. Seufert, Michael; Darzanos, George; Papafili, Ioanna; Łapacz, Roman; Burger, Valentin; Hoßfeld, Tobias. In Socioinformatics - The Social Impact of Interactions between Humans and IT, K. Zweig, W. Neuser, V. Pipek, M. Rohde, I. Scholtes (eds.). Springer International Publishing, 2014.
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  Socially-aware traffic management utilizes social information to optimize traffic management in the Internet in terms of traffic load, energy consumption, or end user satisfaction. Several use cases can benefit from socially-aware traffic management and the performance of overlay applications can be enhanced. We present existing use cases and their socially-aware approaches and solutions, but also raise discussions on additional benefits from the integration of social information into traffic management as well as practical aspects in this domain.

  @incollection{info3-incollection-2014-25, abstract = {Socially-aware traffic management utilizes social information to optimize traffic management in the Internet in terms of traffic load, energy consumption, or end user satisfaction. Several use cases can benefit from socially-aware traffic management and the performance of overlay applications can be enhanced. We present existing use cases and their socially-aware approaches and solutions, but also raise discussions on additional benefits from the integration of social information into traffic management as well as practical aspects in this domain.}, author = {Seufert, Michael and Darzanos, George and Papafili, Ioanna and Łapacz, Roman and Burger, Valentin and Hoßfeld, Tobias}, booktitle = {Socioinformatics - The Social Impact of Interactions between Humans and IT}, editor = {Zweig, Katharina and Neuser, Wolfgang and Pipek, Volkmar and Rohde, Markus and Scholtes, Ingo}, keywords = {smartenit}, month = {08}, publisher = {Springer International Publishing}, title = {Socially-Aware Traffic Management}, year = 2014 }

  %0 Book Section %1 info3-incollection-2014-25 %A Seufert, Michael %A Darzanos, George %A Papafili, Ioanna %A Łapacz, Roman %A Burger, Valentin %A Hoßfeld, Tobias %B Socioinformatics - The Social Impact of Interactions between Humans and IT %D 2014 %E Zweig, Katharina %E Neuser, Wolfgang %E Pipek, Volkmar %E Rohde, Markus %E Scholtes, Ingo %I Springer International Publishing %T Socially-Aware Traffic Management %X Socially-aware traffic management utilizes social information to optimize traffic management in the Internet in terms of traffic load, energy consumption, or end user satisfaction. Several use cases can benefit from socially-aware traffic management and the performance of overlay applications can be enhanced. We present existing use cases and their socially-aware approaches and solutions, but also raise discussions on additional benefits from the integration of social information into traffic management as well as practical aspects in this domain.
• Social Network Analysis in the Enterprise: Challenges and Opportunities. Burger, Valentin; Hock, David; Scholtes, Ingo; Hoßfeld, Tobias; Garcia, David; Seufert, Michael. In Socioinformatics - The Social Impact of Interactions between Humans and IT, K. Zweig, W. Neuser, V. Pipek, M. Rohde, I. Scholtes (eds.). Springer International Publishing, 2014.
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  Enterprise social software tools are increasingly being used to support the communication and collaboration between employees, as well as to facilitate the collaborative organisation of information and knowledge within companies. Not only do these tools help to develop and maintain an efficient social organisation, they also produce massive amounts of fine-grained data on collaborations, communication and other forms of social relationships within an enterprise. In this chapter, we argue that the availability of these data provides unique opportunities to monitor and analyse social structures and their impact on the success and performance of individuals, teams, communities and organisations. We further review methods from the planning, design and optimisation of telecommunication networks and discuss challenges arising when wanting to apply them to optimise the structure of enterprise social networks.

  @incollection{info3-incollection-2014-24, abstract = {Enterprise social software tools are increasingly being used to support the communication and collaboration between employees, as well as to facilitate the collaborative organisation of information and knowledge within companies. Not only do these tools help to develop and maintain an efficient social organisation, they also produce massive amounts of fine-grained data on collaborations, communication and other forms of social relationships within an enterprise. In this chapter, we argue that the availability of these data provides unique opportunities to monitor and analyse social structures and their impact on the success and performance of individuals, teams, communities and organisations. We further review methods from the planning, design and optimisation of telecommunication networks and discuss challenges arising when wanting to apply them to optimise the structure of enterprise social networks.}, author = {Burger, Valentin and Hock, David and Scholtes, Ingo and Hoßfeld, Tobias and Garcia, David and Seufert, Michael}, booktitle = {Socioinformatics - The Social Impact of Interactions between Humans and IT}, editor = {Zweig, Katharina and Neuser, Wolfgang and Pipek, Volkmar and Rohde, Markus and Scholtes, Ingo}, keywords = {myown}, month = {08}, publisher = {Springer International Publishing}, title = {Social Network Analysis in the Enterprise: Challenges and Opportunities}, year = 2014 }

  %0 Book Section %1 info3-incollection-2014-24 %A Burger, Valentin %A Hock, David %A Scholtes, Ingo %A Hoßfeld, Tobias %A Garcia, David %A Seufert, Michael %B Socioinformatics - The Social Impact of Interactions between Humans and IT %D 2014 %E Zweig, Katharina %E Neuser, Wolfgang %E Pipek, Volkmar %E Rohde, Markus %E Scholtes, Ingo %I Springer International Publishing %T Social Network Analysis in the Enterprise: Challenges and Opportunities %X Enterprise social software tools are increasingly being used to support the communication and collaboration between employees, as well as to facilitate the collaborative organisation of information and knowledge within companies. Not only do these tools help to develop and maintain an efficient social organisation, they also produce massive amounts of fine-grained data on collaborations, communication and other forms of social relationships within an enterprise. In this chapter, we argue that the availability of these data provides unique opportunities to monitor and analyse social structures and their impact on the success and performance of individuals, teams, communities and organisations. We further review methods from the planning, design and optimisation of telecommunication networks and discuss challenges arising when wanting to apply them to optimise the structure of enterprise social networks.
• On the computation of entropy production in stationary social networks. Hoßfeld, Tobias; Burger, Valentin; Hinrichsen, Haye; Hirth, Matthias; Tran-Gia, Phuoc. In Social Network Analysis and Mining, 4. 2014.
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  Completing their initial phase of rapid growth, social networks are expected to reach a plateau from where on they are in a statistically stationary state. Such stationary conditions may have different dynamical properties. For example, if each message in a network is followed by a reply in opposite direction, the dynamics is locally balanced. Otherwise, if messages are ignored or forwarded to a different user, one may reach a stationary state with a directed flow of information. To distinguish between the two situations, we propose a quantity called entropy production that was introduced in statistical physics as a measure for non-vanishing probability currents in nonequilibrium stationary states. The proposed quantity closes a gap for characterizing online social networks. As major contribution, we show the relation and difference between entropy production and existing metrics. The comparison shows that computational intensive metrics like centrality can be approximated by entropy production for typical online social networks. To compute the entropy production from real-world measurements, the need for Bayesian inference and the limits of naïve estimates for those probability currents are shown. As further contribution, a general scheme is presented to measure the entropy production in small-world networks using Bayesian inference. The scheme is then applied for a specific example of the R mailing list.

  @article{info3-article-2014-123, abstract = {Completing their initial phase of rapid growth, social networks are expected to reach a plateau from where on they are in a statistically stationary state. Such stationary conditions may have different dynamical properties. For example, if each message in a network is followed by a reply in opposite direction, the dynamics is locally balanced. Otherwise, if messages are ignored or forwarded to a different user, one may reach a stationary state with a directed flow of information. To distinguish between the two situations, we propose a quantity called entropy production that was introduced in statistical physics as a measure for non-vanishing probability currents in nonequilibrium stationary states. The proposed quantity closes a gap for characterizing online social networks. As major contribution, we show the relation and difference between entropy production and existing metrics. The comparison shows that computational intensive metrics like centrality can be approximated by entropy production for typical online social networks. To compute the entropy production from real-world measurements, the need for Bayesian inference and the limits of naïve estimates for those probability currents are shown. As further contribution, a general scheme is presented to measure the entropy production in small-world networks using Bayesian inference. The scheme is then applied for a specific example of the R mailing list.}, author = {Hoßfeld, Tobias and Burger, Valentin and Hinrichsen, Haye and Hirth, Matthias and Tran-Gia, Phuoc}, journal = {Social Network Analysis and Mining}, keywords = {sys:hidden:article}, month = {04}, title = {On the computation of entropy production in stationary social networks}, volume = 4, year = 2014 }

  %0 Journal Article %1 info3-article-2014-123 %A Hoßfeld, Tobias %A Burger, Valentin %A Hinrichsen, Haye %A Hirth, Matthias %A Tran-Gia, Phuoc %D 2014 %J Social Network Analysis and Mining %T On the computation of entropy production in stationary social networks %V 4 %X Completing their initial phase of rapid growth, social networks are expected to reach a plateau from where on they are in a statistically stationary state. Such stationary conditions may have different dynamical properties. For example, if each message in a network is followed by a reply in opposite direction, the dynamics is locally balanced. Otherwise, if messages are ignored or forwarded to a different user, one may reach a stationary state with a directed flow of information. To distinguish between the two situations, we propose a quantity called entropy production that was introduced in statistical physics as a measure for non-vanishing probability currents in nonequilibrium stationary states. The proposed quantity closes a gap for characterizing online social networks. As major contribution, we show the relation and difference between entropy production and existing metrics. The comparison shows that computational intensive metrics like centrality can be approximated by entropy production for typical online social networks. To compute the entropy production from real-world measurements, the need for Bayesian inference and the limits of naïve estimates for those probability currents are shown. As further contribution, a general scheme is presented to measure the entropy production in small-world networks using Bayesian inference. The scheme is then applied for a specific example of the R mailing list.
• Increasing the Coverage of Vantage Points in Distributed Active Network Measurements by Crowdsourcing. Burger, Valentin; Hirth, Matthias; Schwartz, Christian; Hoßfeld, Tobias. In Measurement, Modelling and Evaluation of Computing Systems (MMB 2014). Bamberg, Germany, 2014.
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  Internet video constitutes more than half of all consumer traffic. Most of the video traffic is delivered by content delivery networks (CDNs). The huge amount of traffic from video CDNs poses problems to access providers. To understand and monitor the impact of video traffic on access networks and the topology of CDNs, distributed active measurements are needed. Recently used measurement platforms are mainly hosted in National Research and Education Networks (NRENs). However, the view of these platforms on the CDN is very limited, since the coverage of NRENs is low in developing countries. Furthermore campus networks do not reflect the characteristics of end user access networks. We propose to use crowdsourcing to increase the coverage of vantage points in distributed active network measurements. In this study, we compare measurements of a global CDN conducted in PlanetLab with measurements assigned to workers of a crowdsourcing platform. Therewith, the coverage of vantage points and the sampled part of the global video CDN are analyzed. Our results show that the capability of PlanetLab to measure global CDNs is rather low, since the vast majority of requests is directed to the US. By using the crowdsourcing platform we obtain a diverse set of vantage points that reveals more than twice as many autonomous systems deploying video servers.

  @inproceedings{info3-inproceedings-2014-486, abstract = {Internet video constitutes more than half of all consumer traffic. Most of the video traffic is delivered by content delivery networks (CDNs). The huge amount of traffic from video CDNs poses problems to access providers. To understand and monitor the impact of video traffic on access networks and the topology of CDNs, distributed active measurements are needed. Recently used measurement platforms are mainly hosted in National Research and Education Networks (NRENs). However, the view of these platforms on the CDN is very limited, since the coverage of NRENs is low in developing countries. Furthermore campus networks do not reflect the characteristics of end user access networks. We propose to use crowdsourcing to increase the coverage of vantage points in distributed active network measurements. In this study, we compare measurements of a global CDN conducted in PlanetLab with measurements assigned to workers of a crowdsourcing platform. Therewith, the coverage of vantage points and the sampled part of the global video CDN are analyzed. Our results show that the capability of PlanetLab to measure global CDNs is rather low, since the vast majority of requests is directed to the US. By using the crowdsourcing platform we obtain a diverse set of vantage points that reveals more than twice as many autonomous systems deploying video servers.}, address = {Bamberg, Germany}, author = {Burger, Valentin and Hirth, Matthias and Schwartz, Christian and Hoßfeld, Tobias}, booktitle = {Measurement, Modelling and Evaluation of Computing Systems (MMB 2014)}, keywords = {smartenit}, month = {03}, title = {Increasing the Coverage of Vantage Points in Distributed Active Network Measurements by Crowdsourcing}, year = 2014 }

  %0 Conference Paper %1 info3-inproceedings-2014-486 %A Burger, Valentin %A Hirth, Matthias %A Schwartz, Christian %A Hoßfeld, Tobias %B Measurement, Modelling and Evaluation of Computing Systems (MMB 2014) %C Bamberg, Germany %D 2014 %T Increasing the Coverage of Vantage Points in Distributed Active Network Measurements by Crowdsourcing %X Internet video constitutes more than half of all consumer traffic. Most of the video traffic is delivered by content delivery networks (CDNs). The huge amount of traffic from video CDNs poses problems to access providers. To understand and monitor the impact of video traffic on access networks and the topology of CDNs, distributed active measurements are needed. Recently used measurement platforms are mainly hosted in National Research and Education Networks (NRENs). However, the view of these platforms on the CDN is very limited, since the coverage of NRENs is low in developing countries. Furthermore campus networks do not reflect the characteristics of end user access networks. We propose to use crowdsourcing to increase the coverage of vantage points in distributed active network measurements. In this study, we compare measurements of a global CDN conducted in PlanetLab with measurements assigned to workers of a crowdsourcing platform. Therewith, the coverage of vantage points and the sampled part of the global video CDN are analyzed. Our results show that the capability of PlanetLab to measure global CDNs is rather low, since the vast majority of requests is directed to the US. By using the crowdsourcing platform we obtain a diverse set of vantage points that reveals more than twice as many autonomous systems deploying video servers.

• Resilience in Enterprise Social Networks. Burger, Valentin; Hoßfeld, Tobias; Garcia, David; Seufert, Michael; Scholtes, Ingo; Hock, David. In Workshop Sozioinformatik 2013. Koblenz, Germany, 2013.
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  The goal of human resource management is to ensure an effective company environment. Crucial for a good corporate culture is a comfortable atmosphere and positive social relationships between the employees. The interactions of the people and groups working in the company define their relationships and are reflected in the company's social network. Projections of such networks are Enterprise Social Networks which are more and more integrated in companies. These social networks can be a powerful tool to analyse the structure of a company and indicate potential problems. This extended abstract poses research questions to identify and quantify mechanisms that have an impact on the social network of a company to ensure resilience. To address these questions we make assumptions based on real-world observations for a subsequent model.

  @inproceedings{info3-inproceedings-2013-473, abstract = {The goal of human resource management is to ensure an effective company environment. Crucial for a good corporate culture is a comfortable atmosphere and positive social relationships between the employees. The interactions of the people and groups working in the company define their relationships and are reflected in the company's social network. Projections of such networks are Enterprise Social Networks which are more and more integrated in companies. These social networks can be a powerful tool to analyse the structure of a company and indicate potential problems. This extended abstract poses research questions to identify and quantify mechanisms that have an impact on the social network of a company to ensure resilience. To address these questions we make assumptions based on real-world observations for a subsequent model.}, address = {Koblenz, Germany}, author = {Burger, Valentin and Hoßfeld, Tobias and Garcia, David and Seufert, Michael and Scholtes, Ingo and Hock, David}, booktitle = {Workshop Sozioinformatik 2013}, keywords = {sys:hidden:inproceedings}, month = {09}, title = {Resilience in Enterprise Social Networks}, year = 2013 }

  %0 Conference Paper %1 info3-inproceedings-2013-473 %A Burger, Valentin %A Hoßfeld, Tobias %A Garcia, David %A Seufert, Michael %A Scholtes, Ingo %A Hock, David %B Workshop Sozioinformatik 2013 %C Koblenz, Germany %D 2013 %T Resilience in Enterprise Social Networks %X The goal of human resource management is to ensure an effective company environment. Crucial for a good corporate culture is a comfortable atmosphere and positive social relationships between the employees. The interactions of the people and groups working in the company define their relationships and are reflected in the company's social network. Projections of such networks are Enterprise Social Networks which are more and more integrated in companies. These social networks can be a powerful tool to analyse the structure of a company and indicate potential problems. This extended abstract poses research questions to identify and quantify mechanisms that have an impact on the social network of a company to ensure resilience. To address these questions we make assumptions based on real-world observations for a subsequent model.
• Tracking Cookie 2.0: Erfassungstechniken sozialer Netzwerke. Burger, Valentin. Datev Trendscout, Nürnberg, Germany, 2013, April 15.
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  @presentation{info3-talk-2013-466, address = {Datev Trendscout, Nürnberg, Germany}, author = {Burger, Valentin}, keywords = {sys:hidden:presentation}, month = {04}, title = {Tracking Cookie 2.0: Erfassungstechniken sozialer Netzwerke}, year = 2013 }

  %0 Generic %1 info3-talk-2013-466 %A Burger, Valentin %C Datev Trendscout, Nürnberg, Germany %D 2013 %T Tracking Cookie 2.0: Erfassungstechniken sozialer Netzwerke
• Inter-AS Traffic Characteristics of a Global Content Delivery Network. Burger, Valentin; Hirth, Matthias; Schwartz, Christian; Hoßfeld, Tobias. ITG 5.2.1 Fachgruppentreffen, Würzburg, Germany, 2013, June 28.
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  @presentation{info3-talk-2013-469, address = {ITG 5.2.1 Fachgruppentreffen, Würzburg, Germany}, author = {Burger, Valentin and Hirth, Matthias and Schwartz, Christian and Hoßfeld, Tobias}, keywords = {sys:hidden:presentation}, month = {06}, title = {Inter-AS Traffic Characteristics of a Global Content Delivery Network}, year = 2013 }

  %0 Generic %1 info3-talk-2013-469 %A Burger, Valentin %A Hirth, Matthias %A Schwartz, Christian %A Hoßfeld, Tobias %C ITG 5.2.1 Fachgruppentreffen, Würzburg, Germany %D 2013 %T Inter-AS Traffic Characteristics of a Global Content Delivery Network
• HORST - Home Router Sharing based on Trust. Seufert, Michael; Burger, Valentin; Hoßfeld, Tobias. Zurich, Switzerland, 2013, October.
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  @misc{info3-poster-2013-35, address = {Zurich, Switzerland}, author = {Seufert, Michael and Burger, Valentin and Hoßfeld, Tobias}, booktitle = {Workshop on Social-aware Economic Traffic Management for Overlay and Cloud Applications (SETM 2013)}, keywords = {can}, month = 10, title = {HORST - Home Router Sharing based on Trust}, year = 2013 }

  %0 Generic %1 info3-poster-2013-35 %A Seufert, Michael %A Burger, Valentin %A Hoßfeld, Tobias %B Workshop on Social-aware Economic Traffic Management for Overlay and Cloud Applications (SETM 2013) %C Zurich, Switzerland %D 2013 %T HORST - Home Router Sharing based on Trust
• Socially-Aware Traffic Management. Seufert, Michael; Darzanos, George; Burger, Valentin; Papafili, Ioanna; Hoßfeld, Tobias. In Workshop Sozioinformatik. Koblenz, Germany, 2013.
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  Socially-aware traffic management exploits social signals to optimize traffic management in the Internet in terms of traffic load, energy consumption, or end-user satisfaction. Several use cases can benefit from socially-aware traffic management and the performance of overlay applications can be enhanced. In the talk we show interdisciplinary efforts between communication networks and social network analysis. Specifically, we give an overview on existing use cases and solutions, but also raise discussions at the workshop on additional benefits from the integration of social information into traffic management.

  @inproceedings{info3-inproceedings-2013-471, abstract = {Socially-aware traffic management exploits social signals to optimize traffic management in the Internet in terms of traffic load, energy consumption, or end-user satisfaction. Several use cases can benefit from socially-aware traffic management and the performance of overlay applications can be enhanced. In the talk we show interdisciplinary efforts between communication networks and social network analysis. Specifically, we give an overview on existing use cases and solutions, but also raise discussions at the workshop on additional benefits from the integration of social information into traffic management.}, address = {Koblenz, Germany}, author = {Seufert, Michael and Darzanos, George and Burger, Valentin and Papafili, Ioanna and Hoßfeld, Tobias}, booktitle = {Workshop Sozioinformatik}, keywords = {smartenit}, month = {09}, title = {Socially-Aware Traffic Management}, year = 2013 }

  %0 Conference Paper %1 info3-inproceedings-2013-471 %A Seufert, Michael %A Darzanos, George %A Burger, Valentin %A Papafili, Ioanna %A Hoßfeld, Tobias %B Workshop Sozioinformatik %C Koblenz, Germany %D 2013 %T Socially-Aware Traffic Management %X Socially-aware traffic management exploits social signals to optimize traffic management in the Internet in terms of traffic load, energy consumption, or end-user satisfaction. Several use cases can benefit from socially-aware traffic management and the performance of overlay applications can be enhanced. In the talk we show interdisciplinary efforts between communication networks and social network analysis. Specifically, we give an overview on existing use cases and solutions, but also raise discussions at the workshop on additional benefits from the integration of social information into traffic management.
• Relevant Applications to use SmartenIT. Bocek, Thomas; Schmitt, Corinna; Sperb Machado, Guilherme; Stiller, Burkhard; Hoßfeld, Tobias; Burger, Valentin. Zurich, Switzerland, 2013, October.
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  @misc{info3-poster-2013-36, address = {Zurich, Switzerland}, author = {Bocek, Thomas and Schmitt, Corinna and Sperb Machado, Guilherme and Stiller, Burkhard and Hoßfeld, Tobias and Burger, Valentin}, booktitle = {Workshop on Social-aware Economic Traffic Management for Overlay and Cloud Applications (SETM 2013)}, keywords = {sys:hidden:poster}, month = 10, title = {Relevant Applications to use SmartenIT}, year = 2013 }

  %0 Generic %1 info3-poster-2013-36 %A Bocek, Thomas %A Schmitt, Corinna %A Sperb Machado, Guilherme %A Stiller, Burkhard %A Hoßfeld, Tobias %A Burger, Valentin %B Workshop on Social-aware Economic Traffic Management for Overlay and Cloud Applications (SETM 2013) %C Zurich, Switzerland %D 2013 %T Relevant Applications to use SmartenIT
• HORST - Home Router Sharing based on Trust. Seufert, Michael; Burger, Valentin; Hoßfeld, Tobias. In Workshop on Social-aware Economic Traffic Management for Overlay and Cloud Applications (SETM). Zurich, Switzerland, 2013.
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  Today’s Internet services are increasingly accessed from mobile devices, thus being responsible for growing load in mobile networks. At the same time, more and more WiFi routers are deployed such that a dense coverage of WiFi is available. Results from different related works suggest that there is a high potential of reducing load on the mobile networks by offloading data to WiFi networks, thereby improving mobile users’ quality of experience (QoE) with Internet services. Additionally, the storage of the router could be used for content caching and delivery close to the end user, which is more energy efficient compared to classical content servers, and saves costs for network operators by reducing traffic between autonomous systems. Going one step beyond, we foresee that merging these approaches and augmenting them with social information from online social networks (OSNs) will result both in even less costs for network operators and increased QoE of end users. Therefore, we propose home router sharing based on trust (HORST) - a socially-aware traffic management solution which targets three popular use cases: data offloading to WiFi, content caching/prefetching, and content delivery.

  @inproceedings{info3-inproceedings-2013-476, abstract = {Today’s Internet services are increasingly accessed from mobile devices, thus being responsible for growing load in mobile networks. At the same time, more and more WiFi routers are deployed such that a dense coverage of WiFi is available. Results from different related works suggest that there is a high potential of reducing load on the mobile networks by offloading data to WiFi networks, thereby improving mobile users’ quality of experience (QoE) with Internet services. Additionally, the storage of the router could be used for content caching and delivery close to the end user, which is more energy efficient compared to classical content servers, and saves costs for network operators by reducing traffic between autonomous systems. Going one step beyond, we foresee that merging these approaches and augmenting them with social information from online social networks (OSNs) will result both in even less costs for network operators and increased QoE of end users. Therefore, we propose home router sharing based on trust (HORST) - a socially-aware traffic management solution which targets three popular use cases: data offloading to WiFi, content caching/prefetching, and content delivery.}, address = {Zurich, Switzerland}, author = {Seufert, Michael and Burger, Valentin and Hoßfeld, Tobias}, booktitle = {Workshop on Social-aware Economic Traffic Management for Overlay and Cloud Applications (SETM)}, keywords = {can}, month = 10, title = {HORST - Home Router Sharing based on Trust}, year = 2013 }

  %0 Conference Paper %1 info3-inproceedings-2013-476 %A Seufert, Michael %A Burger, Valentin %A Hoßfeld, Tobias %B Workshop on Social-aware Economic Traffic Management for Overlay and Cloud Applications (SETM) %C Zurich, Switzerland %D 2013 %T HORST - Home Router Sharing based on Trust %X Today’s Internet services are increasingly accessed from mobile devices, thus being responsible for growing load in mobile networks. At the same time, more and more WiFi routers are deployed such that a dense coverage of WiFi is available. Results from different related works suggest that there is a high potential of reducing load on the mobile networks by offloading data to WiFi networks, thereby improving mobile users’ quality of experience (QoE) with Internet services. Additionally, the storage of the router could be used for content caching and delivery close to the end user, which is more energy efficient compared to classical content servers, and saves costs for network operators by reducing traffic between autonomous systems. Going one step beyond, we foresee that merging these approaches and augmenting them with social information from online social networks (OSNs) will result both in even less costs for network operators and increased QoE of end users. Therefore, we propose home router sharing based on trust (HORST) - a socially-aware traffic management solution which targets three popular use cases: data offloading to WiFi, content caching/prefetching, and content delivery.

• Who Profits from Peer-to-Peer File-Sharing? Traffic Optimization Potential in BitTorrent Swarms. Burger, Valentin; Lehrieder, Frank; Hoßfeld, Tobias; Seedorf, Jan. In International Teletraffic Congress (ITC 24). Krakow, Poland, 2012.
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  BitTorrent-based peer-to-peer networks constitute a significant share of Internet traffic. Therefore, the IETF working group on application layer traffic optimization (ALTO) discusses several approaches for guiding the BitTorrent traffic that aim at reducing the large amount of inter-ISP traffic costs caused by these networks. However, performance evaluations of these approaches are mostly limited to artificial scenarios that do not take into account the real Internet topology with its inter-ISP relationships and the actual distribution of BitTorrent users across autonomous systems (AS). In this study, we use measurements of the distribution of a large number of live BitTorrent networks and combine them with the AS-level Internet topology provided by Caida.org. Based on this data, we estimate in which tier of the Internet hierarchy BitTorrent traffic is mainly located and how much optimization potential exists for the different types of ISPs. Therewith, traffic flow and revenue implications of guiding Internet-wide BitTorrent swarms are analyzed. Our results show that tier-1 ISPs profit from the un-managed exchange of peer-to-peer traffic and that these profits significantly decrease when the other ISPs would apply ALTO solutions.

  @inproceedings{info3-inproceedings-2012-451, abstract = {BitTorrent-based peer-to-peer networks constitute a significant share of Internet traffic. Therefore, the IETF working group on application layer traffic optimization (ALTO) discusses several approaches for guiding the BitTorrent traffic that aim at reducing the large amount of inter-ISP traffic costs caused by these networks. However, performance evaluations of these approaches are mostly limited to artificial scenarios that do not take into account the real Internet topology with its inter-ISP relationships and the actual distribution of BitTorrent users across autonomous systems (AS). In this study, we use measurements of the distribution of a large number of live BitTorrent networks and combine them with the AS-level Internet topology provided by Caida.org. Based on this data, we estimate in which tier of the Internet hierarchy BitTorrent traffic is mainly located and how much optimization potential exists for the different types of ISPs. Therewith, traffic flow and revenue implications of guiding Internet-wide BitTorrent swarms are analyzed. Our results show that tier-1 ISPs profit from the un-managed exchange of peer-to-peer traffic and that these profits significantly decrease when the other ISPs would apply ALTO solutions.}, address = {Krakow, Poland}, author = {Burger, Valentin and Lehrieder, Frank and Hoßfeld, Tobias and Seedorf, Jan}, booktitle = {International Teletraffic Congress (ITC 24)}, keywords = {oekonet}, month = {09}, title = {Who Profits from Peer-to-Peer File-Sharing? Traffic Optimization Potential in BitTorrent Swarms}, year = 2012 }

  %0 Conference Paper %1 info3-inproceedings-2012-451 %A Burger, Valentin %A Lehrieder, Frank %A Hoßfeld, Tobias %A Seedorf, Jan %B International Teletraffic Congress (ITC 24) %C Krakow, Poland %D 2012 %T Who Profits from Peer-to-Peer File-Sharing? Traffic Optimization Potential in BitTorrent Swarms %X BitTorrent-based peer-to-peer networks constitute a significant share of Internet traffic. Therefore, the IETF working group on application layer traffic optimization (ALTO) discusses several approaches for guiding the BitTorrent traffic that aim at reducing the large amount of inter-ISP traffic costs caused by these networks. However, performance evaluations of these approaches are mostly limited to artificial scenarios that do not take into account the real Internet topology with its inter-ISP relationships and the actual distribution of BitTorrent users across autonomous systems (AS). In this study, we use measurements of the distribution of a large number of live BitTorrent networks and combine them with the AS-level Internet topology provided by Caida.org. Based on this data, we estimate in which tier of the Internet hierarchy BitTorrent traffic is mainly located and how much optimization potential exists for the different types of ISPs. Therewith, traffic flow and revenue implications of guiding Internet-wide BitTorrent swarms are analyzed. Our results show that tier-1 ISPs profit from the un-managed exchange of peer-to-peer traffic and that these profits significantly decrease when the other ISPs would apply ALTO solutions.
• Enterprise Social Networks. Hoßfeld, Tobias; Hirth, Matthias; Burger, Valentin. Datev Trendscout, Nürnberg, Germany, 2012, May.
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  @presentation{info3-talk-2012-457, address = {Datev Trendscout, Nürnberg, Germany}, author = {Hoßfeld, Tobias and Hirth, Matthias and Burger, Valentin}, keywords = {sys:hidden:presentation}, month = {05}, title = {Enterprise Social Networks}, year = 2012 }

  %0 Generic %1 info3-talk-2012-457 %A Hoßfeld, Tobias %A Hirth, Matthias %A Burger, Valentin %C Datev Trendscout, Nürnberg, Germany %D 2012 %T Enterprise Social Networks
• Information Neutrality: Personalization and Profiling in the Internet. Tran-Gia, Phuoc; Burger, Valentin; Hoßfeld, Tobias; Hirth, Matthias. Datev Trendscout, Nürnberg, Germany, 2012, May.
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  @presentation{info3-talk-2012-458, address = {Datev Trendscout, Nürnberg, Germany}, author = {Tran-Gia, Phuoc and Burger, Valentin and Hoßfeld, Tobias and Hirth, Matthias}, keywords = {sys:hidden:presentation}, month = {05}, title = {Information Neutrality: Personalization and Profiling in the Internet}, year = 2012 }

  %0 Generic %1 info3-talk-2012-458 %A Tran-Gia, Phuoc %A Burger, Valentin %A Hoßfeld, Tobias %A Hirth, Matthias %C Datev Trendscout, Nürnberg, Germany %D 2012 %T Information Neutrality: Personalization and Profiling in the Internet

• Monitoring the User Perceived Quality of SILK-Based Voice Calls. Schlosser, Daniel; Jarschel, Michael; Burger, Valentin; Pries, Rastin. In Australasian Telecommunication Networks and Applications Conference (ATNAC 2010). Auckland, New Zealand, 2010.
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  Quality measurements are required to support VoIP traffic in the Internet. The widely used average Mean Opinion Score is, however, not sufficient for this task. In this paper, we provide a detailed analysis of the Skype SILK codec and compare it with the iLBC and GSM codec. The results show that the SILK codec is superior to the other codecs in scenarios with random and bulk packet loss. This increased tolerance of packet loss enables the option of QoE Monitoring under reasonable network conditions. From analysis, we derive an estimation, which can be used to monitor the MOS value of the users in the worst case. Furthermore, we show how sampling can effectively decrease the required measurement effort. This work was funded by the Federal Ministry of Education and Research of the Federal Republic of Germany (Förderkennzeichen 01BK0917, GLab). The authors alone are responsible for the content of the paper.

  @inproceedings{info3-inproceedings-2010-399, abstract = {Quality measurements are required to support VoIP traffic in the Internet. The widely used average Mean Opinion Score is, however, not sufficient for this task. In this paper, we provide a detailed analysis of the Skype SILK codec and compare it with the iLBC and GSM codec. The results show that the SILK codec is superior to the other codecs in scenarios with random and bulk packet loss. This increased tolerance of packet loss enables the option of QoE Monitoring under reasonable network conditions. From analysis, we derive an estimation, which can be used to monitor the MOS value of the users in the worst case. Furthermore, we show how sampling can effectively decrease the required measurement effort. This work was funded by the Federal Ministry of Education and Research of the Federal Republic of Germany (Förderkennzeichen 01BK0917, GLab). The authors alone are responsible for the content of the paper.}, address = {Auckland, New Zealand}, author = {Schlosser, Daniel and Jarschel, Michael and Burger, Valentin and Pries, Rastin}, booktitle = {Australasian Telecommunication Networks and Applications Conference (ATNAC 2010)}, keywords = {sys:hidden:inproceedings}, month = 11, title = {Monitoring the User Perceived Quality of SILK-Based Voice Calls}, year = 2010 }

  %0 Conference Paper %1 info3-inproceedings-2010-399 %A Schlosser, Daniel %A Jarschel, Michael %A Burger, Valentin %A Pries, Rastin %B Australasian Telecommunication Networks and Applications Conference (ATNAC 2010) %C Auckland, New Zealand %D 2010 %T Monitoring the User Perceived Quality of SILK-Based Voice Calls %X Quality measurements are required to support VoIP traffic in the Internet. The widely used average Mean Opinion Score is, however, not sufficient for this task. In this paper, we provide a detailed analysis of the Skype SILK codec and compare it with the iLBC and GSM codec. The results show that the SILK codec is superior to the other codecs in scenarios with random and bulk packet loss. This increased tolerance of packet loss enables the option of QoE Monitoring under reasonable network conditions. From analysis, we derive an estimation, which can be used to monitor the MOS value of the users in the worst case. Furthermore, we show how sampling can effectively decrease the required measurement effort. This work was funded by the Federal Ministry of Education and Research of the Federal Republic of Germany (Förderkennzeichen 01BK0917, GLab). The authors alone are responsible for the content of the paper.