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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.

[ Abstract ]
[ BibTeX ]
[ EndNote ]

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.

Evaluating the Impact of WiFi Offloading on Mobile Users of HTTP Adaptive Video Streaming. Seufert, Michael. 5th IEEE International Workshop on Quality of Experience for Multimedia Communications (QoEMC), Washington, DC, USA, 2016, December 8.

[ BibTeX ]
[ EndNote ]

@presentation{info3-presentation-2016-10,
  address = {5th IEEE International Workshop on Quality of Experience for Multimedia Communications (QoEMC), Washington, DC, USA},
  author = {Seufert, Michael},
  keywords = {can},
  month = 12,
  title = {Evaluating the Impact of WiFi Offloading on Mobile Users of HTTP Adaptive Video Streaming},
  year = 2016
}

%0 Generic
%1 info3-presentation-2016-10
%A Seufert, Michael
%C 5th IEEE International Workshop on Quality of Experience for Multimedia Communications (QoEMC), Washington, DC, USA
%D 2016
%T Evaluating the Impact of WiFi Offloading on Mobile Users of HTTP Adaptive Video Streaming

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.

[ Abstract ]
[ BibTeX ]
[ EndNote ]

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.

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.

[ Abstract ]
[ BibTeX ]
[ EndNote ]
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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.

Correlating QoE and Technical Parameters of an SAP System in an Enterprise Environment. Borchert, Kathrin; Hirth, Matthias; Zinner, Thomas; Mocanu, Decebal Constantin. In QCMan IEEE Workshop on QoE centric Management. 2016.

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@inproceedings{info3-inproceedings-2016-15,
  author = {Borchert, Kathrin and Hirth, Matthias and Zinner, Thomas and Mocanu, Decebal Constantin},
  booktitle = {QCMan IEEE Workshop on QoE centric Management},
  keywords = {oekonet},
  month = {09},
  title = {Correlating QoE and Technical Parameters of an SAP System in an Enterprise Environment},
  year = 2016
}

%0 Conference Paper
%1 info3-inproceedings-2016-15
%A Borchert, Kathrin
%A Hirth, Matthias
%A Zinner, Thomas
%A Mocanu, Decebal Constantin
%B QCMan IEEE Workshop on QoE centric Management
%D 2016
%T Correlating QoE and Technical Parameters of an SAP System in an Enterprise Environment

Impact of Intermediate Layer on Quality of Experience of HTTP Adaptive Streaming. Seufert, Michael; Hoßfeld, Tobias; Sieber, Christian. In 11th International Conference on Network and Service Management (CNSM). Barcelona, Spain, 2015.

[ Abstract ]
[ BibTeX ]
[ EndNote ]
[ Download ]

HTTP Adaptive Streaming (HAS) adapts the video quality to the current network condition by switching between different quality layers. As HAS was shown to perform better than classical video streaming, it is becoming increasingly popular. Recent research showed that quality switch amplitude and time on layer have an impact on the Quality of Experience (QoE) of HAS. However, those studies focused only on adaptation between two layers so far. This work extends these findings by taking adaptation between three layers into account. Thereby, especially the impact of an intermediate layer on user perceived quality is investigated. Crowdsourcing experiments were conducted in order to collect subjective ratings for adaptation between three layers. The results indicate that the quality of each layer and the time on each layer are important QoE parameters. This encourages the usage of temporal pooling approaches for QoE prediction and QoE-aware traffic management. Therefore, mean pooling of per-frame metrics will be applied and its performance will be validated with the subjective crowdsourcing results.

@inproceedings{info3-inproceedings-2015-532,
  abstract = {HTTP Adaptive Streaming (HAS) adapts the video quality to the current network condition by switching between different quality layers. As HAS was shown to perform better than classical video streaming, it is becoming increasingly popular. Recent research showed that quality switch amplitude and time on layer have an impact on the Quality of Experience (QoE) of HAS. However, those studies focused only on adaptation between two layers so far. This work extends these findings by taking adaptation between three layers into account. Thereby, especially the impact of an intermediate layer on user perceived quality is investigated. Crowdsourcing experiments were conducted in order to collect subjective ratings for adaptation between three layers. The results indicate that the quality of each layer and the time on each layer are important QoE parameters. This encourages the usage of temporal pooling approaches for QoE prediction and QoE-aware traffic management. Therefore, mean pooling of per-frame metrics will be applied and its performance will be validated with the subjective crowdsourcing results.},
  address = {Barcelona, Spain},
  author = {Seufert, Michael and Hoßfeld, Tobias and Sieber, Christian},
  booktitle = {11th International Conference on Network and Service Management (CNSM)},
  keywords = {can},
  month = 11,
  title = {Impact of Intermediate Layer on Quality of Experience of HTTP Adaptive Streaming},
  year = 2015
}

%0 Conference Paper
%1 info3-inproceedings-2015-532
%A Seufert, Michael
%A Hoßfeld, Tobias
%A Sieber, Christian
%B 11th International Conference on Network and Service Management (CNSM)
%C Barcelona, Spain
%D 2015
%T Impact of Intermediate Layer on Quality of Experience of HTTP Adaptive Streaming
%X HTTP Adaptive Streaming (HAS) adapts the video quality to the current network condition by switching between different quality layers. As HAS was shown to perform better than classical video streaming, it is becoming increasingly popular. Recent research showed that quality switch amplitude and time on layer have an impact on the Quality of Experience (QoE) of HAS. However, those studies focused only on adaptation between two layers so far. This work extends these findings by taking adaptation between three layers into account. Thereby, especially the impact of an intermediate layer on user perceived quality is investigated. Crowdsourcing experiments were conducted in order to collect subjective ratings for adaptation between three layers. The results indicate that the quality of each layer and the time on each layer are important QoE parameters. This encourages the usage of temporal pooling approaches for QoE prediction and QoE-aware traffic management. Therefore, mean pooling of per-frame metrics will be applied and its performance will be validated with the subjective crowdsourcing results.

Impact of Intermediate Layer on Quality of Experience of HTTP Adaptive Streaming. Seufert, Michael; Hoßfeld, Tobias; Sieber, Christian. Barcelona, Spain, 2015, November.

[ BibTeX ]
[ EndNote ]

@misc{info3-poster-2015-40,
  address = {Barcelona, Spain},
  author = {Seufert, Michael and Hoßfeld, Tobias and Sieber, Christian},
  booktitle = {11th International Conference on Network and Service Management (CNSM)},
  keywords = {can},
  month = 11,
  title = {Impact of Intermediate Layer on Quality of Experience of HTTP Adaptive Streaming.},
  year = 2015
}

%0 Generic
%1 info3-poster-2015-40
%A Seufert, Michael
%A Hoßfeld, Tobias
%A Sieber, Christian
%B 11th International Conference on Network and Service Management (CNSM)
%C Barcelona, Spain
%D 2015
%T Impact of Intermediate Layer on Quality of Experience of HTTP Adaptive Streaming.

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.

[ Abstract ]
[ BibTeX ]
[ EndNote ]
[ Download ]

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.

Analysis of Group-based Communication in WhatsApp. Seufert, Michael. 7th EAI International Conference on Mobile Networks and Management (MONAMI), Santander, Spain, 2015, September 18.

[ BibTeX ]
[ EndNote ]

@presentation{info3-talk-2015-494,
  address = {7th EAI International Conference on Mobile Networks and Management (MONAMI), Santander, Spain},
  author = {Seufert, Michael},
  keywords = {smartenit},
  month = {09},
  title = {Analysis of Group-based Communication in WhatsApp},
  year = 2015
}

%0 Generic
%1 info3-talk-2015-494
%A Seufert, Michael
%C 7th EAI International Conference on Mobile Networks and Management (MONAMI), Santander, Spain
%D 2015
%T Analysis of Group-based Communication in WhatsApp

Analysis of Group-based Communication in WhatsApp. Seufert, Michael; Schwind, Anika; Hoßfeld, Tobias; Tran-Gia, Phuoc. In 7th EAI International Conference on Mobile Networks and Management (MONAMI). Santander, Spain, 2015.

[ Abstract ]
[ BibTeX ]
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This work investigates group-based communication in WhatsApp based on a survey and the analysis of messaging logs. The characteristics of WhatsApp group chats in terms of usage and topics are outlined. We present a classification based on the topic of the group and classify anonymized messaging logs based on message statistics. Finally, we model WhatsApp group communication with a semi-Markov process, which can be used to generate network traffic similar to real messaging logs.

@inproceedings{info3-inproceedings-2015-523,
  abstract = {This work investigates group-based communication in WhatsApp based on a survey and the analysis of messaging logs. The characteristics of WhatsApp group chats in terms of usage and topics are outlined. We present a classification based on the topic of the group and classify anonymized messaging logs based on message statistics. Finally, we model WhatsApp group communication with a semi-Markov process, which can be used to generate network traffic similar to real messaging logs.},
  address = {Santander, Spain},
  author = {Seufert, Michael and Schwind, Anika and Hoßfeld, Tobias and Tran-Gia, Phuoc},
  booktitle = {7th EAI International Conference on Mobile Networks and Management (MONAMI)},
  keywords = {smartenit},
  month = {09},
  title = {Analysis of Group-based Communication in WhatsApp},
  year = 2015
}

%0 Conference Paper
%1 info3-inproceedings-2015-523
%A Seufert, Michael
%A Schwind, Anika
%A Hoßfeld, Tobias
%A Tran-Gia, Phuoc
%B 7th EAI International Conference on Mobile Networks and Management (MONAMI)
%C Santander, Spain
%D 2015
%T Analysis of Group-based Communication in WhatsApp
%X This work investigates group-based communication in WhatsApp based on a survey and the analysis of messaging logs. The characteristics of WhatsApp group chats in terms of usage and topics are outlined. We present a classification based on the topic of the group and classify anonymized messaging logs based on message statistics. Finally, we model WhatsApp group communication with a semi-Markov process, which can be used to generate network traffic similar to real messaging logs.

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.

[ Abstract ]
[ BibTeX ]
[ EndNote ]
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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.

Identifying QoE Optimal Adaptation of HTTP Adaptive Streaming Based on Subjective Studies. Hoßfeld, Tobias; Seufert, Michael; Sieber, Christian; Zinner, Thomas; Tran-Gia, Phuoc. In Computer Networks, 81, pp. 320–332. 2015.

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HTTP Adaptive Streaming (HAS) technologies, e.g., Apple HLS or MPEG-DASH, automatically adapt the delivered video quality to the available network. This reduces stalling of the video but additionally introduces quality switches, which also influence the user-perceived Quality of Experience (QoE). In this work, we conduct a subjective study to identify the impact of adaptation parameters on QoE. The results indicate that the video quality has to be maximized first, and that the number of quality switches is less important. Based on these results, a method to compute the optimal QoE-optimal adaptation strategy for HAS on a per user basis with mixed-integer linear programming is presented. This QoE-optimal adaptation enables the benchmarking of existing adaptation algorithms for any given network condition. Moreover, the investigated concept is extended to a multi-user IPTV scenario. The question is answered whether video quality, and thereby, the QoE can be shared in a fair manner among the involved users.

@article{info3-article-2015-132,
  abstract = {HTTP Adaptive Streaming (HAS) technologies, e.g., Apple HLS or MPEG-DASH, automatically adapt the delivered video quality to the available network. This reduces stalling of the video but additionally introduces quality switches, which also influence the user-perceived Quality of Experience (QoE). In this work, we conduct a subjective study to identify the impact of adaptation parameters on QoE. The results indicate that the video quality has to be maximized first, and that the number of quality switches is less important. Based on these results, a method to compute the optimal QoE-optimal adaptation strategy for HAS on a per user basis with mixed-integer linear programming is presented. This QoE-optimal adaptation enables the benchmarking of existing adaptation algorithms for any given network condition. Moreover, the investigated concept is extended to a multi-user IPTV scenario. The question is answered whether video quality, and thereby, the QoE can be shared in a fair manner among the involved users.},
  author = {Hoßfeld, Tobias and Seufert, Michael and Sieber, Christian and Zinner, Thomas and Tran-Gia, Phuoc},
  journal = {Computer Networks},
  keywords = {sys:hidden:article},
  month = {04},
  pages = {320-332},
  title = {Identifying QoE Optimal Adaptation of HTTP Adaptive Streaming Based on Subjective Studies},
  volume = 81,
  year = 2015
}

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

A Survey on Quality of Experience of HTTP Adaptive Streaming. Seufert, Michael; Egger, Sebastian; Slanina, Martin; Zinner, Thomas; Hoßfeld, Tobias; Tran-Gia, Phuoc. In IEEE Communications Surveys & Tutorials, 17, pp. 469–492. 2015.

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

@article{info3-article-2015-126,
  abstract = {Changing network conditions pose severe problems to video streaming in the Internet. HTTP adaptive streaming (HAS) is a technology employed by numerous video services which relieves these issues by adapting the video to the current network conditions. It enables service providers to improve resource utilization and Quality of Experience (QoE) by incorporating information from different layers in order to deliver and adapt a video in its best possible quality. Thereby, it allows to take into account end user device capabilities, available video quality levels, current network conditions, and current server load. For end users, the major benefits of HAS compared to classical HTTP video streaming are reduced interruptions of the video playback and higher bandwidth utilization, which both generally result in a higher QoE. Adaptation is possible by changing the frame rate, resolution, or quantization of the video, which can be done with various adaptation strategies and related client- and server-side actions. The technical development of HAS, existing open standardized solutions, but also proprietary solutions are reviewed in this article as fundament to derive the QoE influence factors which emerge as a result of adaptation. The main contribution is a comprehensive survey of QoE related works from human computer interaction and networking domains which are structured according to the QoE impact of video adaptation. To be more precise, subjective studies which cover QoE aspects of adaptation dimensions and strategies are revisited. As a result, QoE influence factors of HAS and corresponding QoE models are identified, but also open issues and conflicting results are discussed. Furthermore, technical influence factors, which are often ignored in the context of HAS, affect perceptual QoE influence factors and are consequently analyzed. This survey gives the reader an overview of the current state of the art and recent developments. At the same time it targets networking researchers who develop new solutions for HTTP video streaming or assess video streaming from a user centric point of view. Therefore, the article is a major step towards truly improving HAS.},
  author = {Seufert, Michael and Egger, Sebastian and Slanina, Martin and Zinner, Thomas and Hoßfeld, Tobias and Tran-Gia, Phuoc},
  journal = {IEEE Communications Surveys & Tutorials},
  keywords = {sys:hidden:article},
  month = {03},
  pages = {469-492},
  title = {A Survey on Quality of Experience of HTTP Adaptive Streaming},
  volume = 17,
  year = 2015
}

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

Close to Optimum? User-centric Evaluation of Adaptation Logics for HTTP Adaptive Streaming. Hoßfeld, Tobias; Seufert, Michael; Sieber, Christian; Zinner, Thomas; Tran-Gia, Phuoc. In PIK - Praxis der Informationsverarbeitung und Kommunikation, 37, pp. 275–285. 2014.

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HTTP Adaptive Streaming (HAS) is the de-facto standard for over-the-top (OTT) video streaming services. It allows to react to fluctuating network conditions on short time scales by adapting the video bit rate in order to avoid stalling of the video playback. With HAS the video content is split into small segments of a few seconds playtime each, which are available in different bit rates, i.e., quality level representations. Depending on the current conditions, the adaptation algorithm on the client side chooses the appropriate quality level and downloads the respective segment. This allows to avoid stalling, which is seen as the worst possible disturbance of HTTP video streaming, to the most possible extend. Nevertheless, the user perceived Quality of Experience (QoE) may be affected, namely by playing back lower qualities and by switching between different qualities. Therefore, adaptation algorithms are desired which maximize the user’sQoEfor the currently available network resources. Many downloading strategies have been proposed in literature, but a solid user-centric comparison of these mechanisms among each other and with the global optimum is missing. The major contributions of this work are as follows. A proper analysis of the influence of quality switches and played out representations on QoE is conducted by means of subjective user studies. The results suggest that, in order to optimize QoE, first, the quality level of the video stream has to be maximized and second, the number of quality switches should be minimized. Based on our findings, a QoEoptimization problem is formulated and the performance of our proposed algorithm is compared to other algorithms and to the QoE-optimal adaptation.

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

%0 Journal Article
%1 info3-article-2014-127
%A Hoßfeld, Tobias
%A Seufert, Michael
%A Sieber, Christian
%A Zinner, Thomas
%A Tran-Gia, Phuoc
%D 2014
%J PIK - Praxis der Informationsverarbeitung und Kommunikation
%P 275-285
%T Close to Optimum? User-centric Evaluation of Adaptation Logics for HTTP Adaptive Streaming
%V 37
%X HTTP Adaptive Streaming (HAS) is the de-facto standard for over-the-top (OTT) video streaming services. It allows to react to fluctuating network conditions on short time scales by adapting the video bit rate in order to avoid stalling of the video playback. With HAS the video content is split into small segments of a few seconds playtime each, which are available in different bit rates, i.e., quality level representations. Depending on the current conditions, the adaptation algorithm on the client side chooses the appropriate quality level and downloads the respective segment. This allows to avoid stalling, which is seen as the worst possible disturbance of HTTP video streaming, to the most possible extend. Nevertheless, the user perceived Quality of Experience (QoE) may be affected, namely by playing back lower qualities and by switching between different qualities. Therefore, adaptation algorithms are desired which maximize the user’sQoEfor the currently available network resources. Many downloading strategies have been proposed in literature, but a solid user-centric comparison of these mechanisms among each other and with the global optimum is missing. The major contributions of this work are as follows. A proper analysis of the influence of quality switches and played out representations on QoE is conducted by means of subjective user studies. The results suggest that, in order to optimize QoE, first, the quality level of the video stream has to be maximized and second, the number of quality switches should be minimized. Based on our findings, a QoEoptimization problem is formulated and the performance of our proposed algorithm is compared to other algorithms and to the QoE-optimal adaptation.

Assessing Effect Sizes of Influence Factors Towards a QoE Model for HTTP Adaptive Streaming. Seufert, Michael. 6th International Workshop on Quality of Multimedia Experience (QoMEX), Singapore, 2014, September 19.

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@presentation{info3-talk-2014-488,
  address = {6th International Workshop on Quality of Multimedia Experience (QoMEX), Singapore},
  author = {Seufert, Michael},
  keywords = {smartenit},
  month = {09},
  title = {Assessing Effect Sizes of Influence Factors Towards a QoE Model for HTTP Adaptive Streaming},
  year = 2014
}

%0 Generic
%1 info3-talk-2014-488
%A Seufert, Michael
%C 6th International Workshop on Quality of Multimedia Experience (QoMEX), Singapore
%D 2014
%T Assessing Effect Sizes of Influence Factors Towards a QoE Model for HTTP Adaptive Streaming

Assessing Effect Sizes of Influence Factors Towards a QoE Model for HTTP Adaptive Streaming. Hoßfeld, Tobias; Seufert, Michael; Sieber, Christian; Zinner, Thomas. In 6th International Workshop on Quality of Multimedia Experience (QoMEX). Singapore, 2014.

[ Abstract ]
[ BibTeX ]
[ EndNote ]
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HTTP Adaptive Streaming (HAS) is employed by more and more video streaming services in the Internet. It allows to adapt the downloaded video quality to the current network conditions, and thus, avoids stalling (i.e., playback interruptions) to the greatest possible extend. The adaptation of video streams is done by switching between different quality representation levels, which influences the user perceived quality of the video stream. In this work, the influence of several adaptation parameters, namely, switch amplitude (i.e., quality level difference), switching frequency, and recency effects, on Quality of Experience (QoE) is investigated. Therefore, crowdsourcing experiments were conducted in order to collect subjective ratings for different adaptation-related test conditions. The results of these subjective studies indicate the influence of the adaptation parameters, and based on these findings a simplified QoE model for HAS is presented, which only relies on the switch amplitude and the playback time of each layer.

@inproceedings{info3-inproceedings-2014-503,
  abstract = {HTTP Adaptive Streaming (HAS) is employed by more and more video streaming services in the Internet. It allows to adapt the downloaded video quality to the current network conditions, and thus, avoids stalling (i.e., playback interruptions) to the greatest possible extend. The adaptation of video streams is done by switching between different quality representation levels, which influences the user perceived quality of the video stream. In this work, the influence of several adaptation parameters, namely, switch amplitude (i.e., quality level difference), switching frequency, and recency effects, on Quality of Experience (QoE) is investigated. Therefore, crowdsourcing experiments were conducted in order to collect subjective ratings for different adaptation-related test conditions. The results of these subjective studies indicate the influence of the adaptation parameters, and based on these findings a simplified QoE model for HAS is presented, which only relies on the switch amplitude and the playback time of each layer.},
  address = {Singapore},
  author = {Hoßfeld, Tobias and Seufert, Michael and Sieber, Christian and Zinner, Thomas},
  booktitle = {6th International Workshop on Quality of Multimedia Experience (QoMEX)},
  keywords = {smartenit},
  month = {09},
  title = {Assessing Effect Sizes of Influence Factors Towards a QoE Model for HTTP Adaptive Streaming},
  year = 2014
}

%0 Conference Paper
%1 info3-inproceedings-2014-503
%A Hoßfeld, Tobias
%A Seufert, Michael
%A Sieber, Christian
%A Zinner, Thomas
%B 6th International Workshop on Quality of Multimedia Experience (QoMEX)
%C Singapore
%D 2014
%T Assessing Effect Sizes of Influence Factors Towards a QoE Model for HTTP Adaptive Streaming
%X HTTP Adaptive Streaming (HAS) is employed by more and more video streaming services in the Internet. It allows to adapt the downloaded video quality to the current network conditions, and thus, avoids stalling (i.e., playback interruptions) to the greatest possible extend. The adaptation of video streams is done by switching between different quality representation levels, which influences the user perceived quality of the video stream. In this work, the influence of several adaptation parameters, namely, switch amplitude (i.e., quality level difference), switching frequency, and recency effects, on Quality of Experience (QoE) is investigated. Therefore, crowdsourcing experiments were conducted in order to collect subjective ratings for different adaptation-related test conditions. The results of these subjective studies indicate the influence of the adaptation parameters, and based on these findings a simplified QoE model for HAS is presented, which only relies on the switch amplitude and the playback time of each layer.

Crowdsourced Subjective User Study Results on QoE Influence Factors of HTTP Adaptive Streaming. Technical Report (491), . Hoßfeld, Tobias; Seufert, Michael; Sieber, Christian; Zinner, Thomas. University of Wuerzburg, 2014.

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@techreport{info3-techreport-2014-265,
  author = {Hoßfeld, Tobias and Seufert, Michael and Sieber, Christian and Zinner, Thomas},
  institution = {University of Wuerzburg},
  keywords = {sys:hidden:techreport},
  month = {07},
  number = 491,
  title = {Crowdsourced Subjective User Study Results on QoE Influence Factors of HTTP Adaptive Streaming},
  year = 2014
}

%0 Report
%1 info3-techreport-2014-265
%A Hoßfeld, Tobias
%A Seufert, Michael
%A Sieber, Christian
%A Zinner, Thomas
%D 2014
%N 491
%T Crowdsourced Subjective User Study Results on QoE Influence Factors of HTTP Adaptive Streaming

A Survey on Quality of Experience of HTTP Adaptive Streaming. Technical Report (490), . Seufert, Michael; Egger, Sebastian; Slanina, Martin; Zinner, Thomas; Hoßfeld, Tobias; Tran-Gia, Phuoc. University of Wuerzburg, 2014.

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@techreport{info3-techreport-2014-264,
  author = {Seufert, Michael and Egger, Sebastian and Slanina, Martin and Zinner, Thomas and Hoßfeld, Tobias and Tran-Gia, Phuoc},
  institution = {University of Wuerzburg},
  keywords = {sys:hidden:techreport},
  month = {04},
  number = 490,
  title = {A Survey on Quality of Experience of HTTP Adaptive Streaming},
  year = 2014
}

%0 Report
%1 info3-techreport-2014-264
%A Seufert, Michael
%A Egger, Sebastian
%A Slanina, Martin
%A Zinner, Thomas
%A Hoßfeld, Tobias
%A Tran-Gia, Phuoc
%D 2014
%N 490
%T A Survey on Quality of Experience of HTTP Adaptive Streaming

QoE of YouTube Video Streaming for Current Internet Transport Protocols. Hoßfeld, Tobias; Schatz, Raimund; Krieger, Udo. In Measurement, Modelling and Evaluation of Computing Systems (MMB 2014). Bamberg, Germany, 2014.

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Video streaming currently dominates global Internet traffic and will be of even increasing importance in the future. In this paper we assess the impact of the underlying transport protocol on the user perceived quality for video streaming using YouTube as example. In particular, we investigate whether UDP or TCP fits better for Video-on-Demand delivery from the end user's perspective, when the video is transmitted over a bottleneck link. For UDP based streaming, the bottleneck link results in spatial and temporal video artifacts, decreasing the video quality. In contrast, in the case of TCP based streaming, the displayed content itself is not disturbed but playback suffers from stalling due to rebufferung. The results of subjective user studies for both scenarios are analyzed in order to assess the transport protocol influences on Quality of Experience of YouTube. To this end, application-level measurements are conducted for YouTube streaming over a network bottleneck in order to develop models for realistic stalling patterns. Furthermore, mapping functions are derived that accurately describe the relationship between network-level impairments and QoE for both protocols.

@inproceedings{info3-inproceedings-2014-485,
  abstract = {Video streaming currently dominates global Internet traffic and will be of even increasing importance in the future. In this paper we assess the impact of the underlying transport protocol on the user perceived quality for video streaming using YouTube as example. In particular, we investigate whether UDP or TCP fits better for Video-on-Demand delivery from the end user's perspective, when the video is transmitted over a bottleneck link. For UDP based streaming, the bottleneck link results in spatial and temporal video artifacts, decreasing the video quality. In contrast, in the case of TCP based streaming, the displayed content itself is not disturbed but playback suffers from stalling due to rebufferung. The results of subjective user studies for both scenarios are analyzed in order to assess the transport protocol influences on Quality of Experience of YouTube. To this end, application-level measurements are conducted for YouTube streaming over a network bottleneck in order to develop models for realistic stalling patterns. Furthermore, mapping functions are derived that accurately describe the relationship between network-level impairments and QoE for both protocols.},
  address = {Bamberg, Germany},
  author = {Hoßfeld, Tobias and Schatz, Raimund and Krieger, Udo},
  booktitle = {Measurement, Modelling and Evaluation of Computing Systems (MMB 2014)},
  keywords = {demobenefit},
  month = {03},
  title = {QoE of YouTube Video Streaming for Current Internet Transport Protocols},
  year = 2014
}

%0 Conference Paper
%1 info3-inproceedings-2014-485
%A Hoßfeld, Tobias
%A Schatz, Raimund
%A Krieger, Udo
%B Measurement, Modelling and Evaluation of Computing Systems (MMB 2014)
%C Bamberg, Germany
%D 2014
%T QoE of YouTube Video Streaming for Current Internet Transport Protocols
%X Video streaming currently dominates global Internet traffic and will be of even increasing importance in the future. In this paper we assess the impact of the underlying transport protocol on the user perceived quality for video streaming using YouTube as example. In particular, we investigate whether UDP or TCP fits better for Video-on-Demand delivery from the end user's perspective, when the video is transmitted over a bottleneck link. For UDP based streaming, the bottleneck link results in spatial and temporal video artifacts, decreasing the video quality. In contrast, in the case of TCP based streaming, the displayed content itself is not disturbed but playback suffers from stalling due to rebufferung. The results of subjective user studies for both scenarios are analyzed in order to assess the transport protocol influences on Quality of Experience of YouTube. To this end, application-level measurements are conducted for YouTube streaming over a network bottleneck in order to develop models for realistic stalling patterns. Furthermore, mapping functions are derived that accurately describe the relationship between network-level impairments and QoE for both protocols.

Best Practices for QoE Crowdtesting: QoE Assessment with Crowdsourcing. Hoßfeld, Tobias; Keimel, Christian; Hirth, Matthias; Gardlo, Bruno; Habigt, Julian; Diepold, Klaus; Tran-Gia, Phuoc. In Transactions on Multimedia, 16. 2014.

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Quality of Experience (QoE) in multimedia applications is closely linked to the end users’ perception and therefore its assessment requires subjective user studies in order to evaluate the degree of delight or annoyance as experienced by the users. QoE crowdtesting refers to QoE assessment using crowdsourcing, where anonymous test subjects conduct subjective tests remotely in their preferred environment. The advantages of QoE crowdtesting lie not only in the reduced time and costs for the tests, but also in a large and diverse panel of international, geographically distributed users in realistic user settings. However, conceptual and technical challenges emerge due to the remote test settings. Key issues arising from QoE crowdtesting include the reliability of user ratings, the influence of incentives, payment schemes and the unknown environmental context of the tests on the results. In order to counter these issues, strategies and methods need to be developed, included in the test design, and also implemented in the actual test campaign, while statistical methods are required to identify reliable user ratings and to ensure high data quality. This contribution therefore provides a collection of best practices addressing these issues based on our experience gained in a large set of conducted QoE crowdtesting studies. The focus of this article is in particular on the issue of reliability and we use video quality assessment as an example for the proposed best practices, showing that our recommended two-stage QoE crowdtesting design leads to more reliable results.

@article{info3-article-2014-117,
  abstract = {Quality of Experience (QoE) in multimedia applications is closely linked to the end users’ perception and therefore its assessment requires subjective user studies in order to evaluate the degree of delight or annoyance as experienced by the users. QoE crowdtesting refers to QoE assessment using crowdsourcing, where anonymous test subjects conduct subjective tests remotely in their preferred environment. The advantages of QoE crowdtesting lie not only in the reduced time and costs for the tests, but also in a large and diverse panel of international, geographically distributed users in realistic user settings. However, conceptual and technical challenges emerge due to the remote test settings. Key issues arising from QoE crowdtesting include the reliability of user ratings, the influence of incentives, payment schemes and the unknown environmental context of the tests on the results. In order to counter these issues, strategies and methods need to be developed, included in the test design, and also implemented in the actual test campaign, while statistical methods are required to identify reliable user ratings and to ensure high data quality. This contribution therefore provides a collection of best practices addressing these issues based on our experience gained in a large set of conducted QoE crowdtesting studies. The focus of this article is in particular on the issue of reliability and we use video quality assessment as an example for the proposed best practices, showing that our recommended two-stage QoE crowdtesting design leads to more reliable results.},
  author = {Hoßfeld, Tobias and Keimel, Christian and Hirth, Matthias and Gardlo, Bruno and Habigt, Julian and Diepold, Klaus and Tran-Gia, Phuoc},
  journal = {Transactions on Multimedia},
  keywords = {sys:hidden:article},
  month = {02},
  title = {Best Practices for QoE Crowdtesting: QoE Assessment with Crowdsourcing},
  volume = 16,
  year = 2014
}

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

Trade-Offs for Video-Providers in LTE Networks: Smartphone Energy Consumption Vs Wasted Traffic. Schwartz, Christian; Scheib, Marc; Hoßfeld, Tobias; Tran-Gia, Phuoc; Manuel Gimenez-Guzman, Jose. In 22nd International Teletraffic Congress Specialist Seminar on Energy Efficient and Green Networking. Christchurch, New Zealand, 2013.

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Long Term Evolution (LTE) networks provide broadband Internet access to mobile users. One of the main use cases for LTE is a mobile video. When selecting a video transmis- sion mechanism, a video provider has to consider different and orthogonal metrics. The consumer expects a high video Quality of Experience (QoE) and a low energy consumption during download and playback. The video provider is interested in minimizing its resources and corresponding costs, like bandwidth and wasted traffic. Wasted traffic occurs if a user aborts and additional video data is already downloaded but not played out, consuming resources unnecessarily. This raises the questions 1) how a video provider delivers the video contents while reducing the operational costs and satisfying the customers demands 2) what is the influence of the customer abort behaviour. To answer these questions, we first study the influence of mechanism selection on energy consumption and wasted traffic. Second, we show that the different user models do not influence the wasted traffic significantly. Finally, we provide parameter se- lection guidelines for the Streaming mechanism, which are shown to satisfy better both the requirements of the video provider as well as those of the customer, to achieve Pareto optimal results with regard to the smartphone energy consumption and wasted traffic.

@inproceedings{info3-inproceedings-2013-482,
  abstract = {Long Term Evolution (LTE) networks provide broadband Internet access to mobile users. One of the main use cases for LTE is a mobile video. When selecting a video transmis- sion mechanism, a video provider has to consider different and orthogonal metrics. The consumer expects a high video Quality of Experience (QoE) and a low energy consumption during download and playback. The video provider is interested in minimizing its resources and corresponding costs, like bandwidth and wasted traffic. Wasted traffic occurs if a user aborts and additional video data is already downloaded but not played out, consuming resources unnecessarily. This raises the questions 1) how a video provider delivers the video contents while reducing the operational costs and satisfying the customers demands 2) what is the influence of the customer abort behaviour. To answer these questions, we first study the influence of mechanism selection on energy consumption and wasted traffic. Second, we show that the different user models do not influence the wasted traffic significantly. Finally, we provide parameter se- lection guidelines for the Streaming mechanism, which are shown to satisfy better both the requirements of the video provider as well as those of the customer, to achieve Pareto optimal results with regard to the smartphone energy consumption and wasted traffic.},
  address = {Christchurch, New Zealand},
  author = {Schwartz, Christian and Scheib, Marc and Hoßfeld, Tobias and Tran-Gia, Phuoc and Manuel Gimenez-Guzman, Jose},
  booktitle = {22nd International Teletraffic Congress Specialist Seminar on Energy Efficient and Green Networking},
  keywords = {smartenit},
  month = 11,
  title = {Trade-Offs for Video-Providers in LTE Networks: Smartphone Energy Consumption Vs Wasted Traffic},
  year = 2013
}

%0 Conference Paper
%1 info3-inproceedings-2013-482
%A Schwartz, Christian
%A Scheib, Marc
%A Hoßfeld, Tobias
%A Tran-Gia, Phuoc
%A Manuel Gimenez-Guzman, Jose
%B 22nd International Teletraffic Congress Specialist Seminar on Energy Efficient and Green Networking
%C Christchurch, New Zealand
%D 2013
%T Trade-Offs for Video-Providers in LTE Networks: Smartphone Energy Consumption Vs Wasted Traffic
%X Long Term Evolution (LTE) networks provide broadband Internet access to mobile users. One of the main use cases for LTE is a mobile video. When selecting a video transmis- sion mechanism, a video provider has to consider different and orthogonal metrics. The consumer expects a high video Quality of Experience (QoE) and a low energy consumption during download and playback. The video provider is interested in minimizing its resources and corresponding costs, like bandwidth and wasted traffic. Wasted traffic occurs if a user aborts and additional video data is already downloaded but not played out, consuming resources unnecessarily. This raises the questions 1) how a video provider delivers the video contents while reducing the operational costs and satisfying the customers demands 2) what is the influence of the customer abort behaviour. To answer these questions, we first study the influence of mechanism selection on energy consumption and wasted traffic. Second, we show that the different user models do not influence the wasted traffic significantly. Finally, we provide parameter se- lection guidelines for the Streaming mechanism, which are shown to satisfy better both the requirements of the video provider as well as those of the customer, to achieve Pareto optimal results with regard to the smartphone energy consumption and wasted traffic.

Asking Costs Little? The Impact of Tasks in Video QoE Studies on User Behavior and User Ratings. Sackl, Andreas; Seufert, Michael; Hoßfeld, Tobias. In 4th International Workshop on Perceptual Quality of Systems (PQS). Vienna, Austria, 2013.

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Three crowdsourcing video QoE studies have been conducted to investigate the influence of tasks on user behavior and quality perception. Different dimensions of tasks have been applied to impaired video clips and their impact on task success, focus time, and QoE was measured. Our findings suggest that task presence or absence has no influence on the user. However, continuous tasks can improve the focus times of users, and hard tasks are suitable to filter unreliable participants.

@inproceedings{info3-inproceedings-2013-467,
  abstract = {Three crowdsourcing video QoE studies have been conducted to investigate the influence of tasks on user behavior and quality perception. Different dimensions of tasks have been applied to impaired video clips and their impact on task success, focus time, and QoE was measured. Our findings suggest that task presence or absence has no influence on the user. However, continuous tasks can improve the focus times of users, and hard tasks are suitable to filter unreliable participants.},
  address = {Vienna, Austria},
  author = {Sackl, Andreas and Seufert, Michael and Hoßfeld, Tobias},
  booktitle = {4th International Workshop on Perceptual Quality of Systems (PQS)},
  keywords = {oekonet},
  month = {09},
  title = {Asking Costs Little? The Impact of Tasks in Video QoE Studies on User Behavior and User Ratings},
  year = 2013
}

%0 Conference Paper
%1 info3-inproceedings-2013-467
%A Sackl, Andreas
%A Seufert, Michael
%A Hoßfeld, Tobias
%B 4th International Workshop on Perceptual Quality of Systems (PQS)
%C Vienna, Austria
%D 2013
%T Asking Costs Little? The Impact of Tasks in Video QoE Studies on User Behavior and User Ratings
%X Three crowdsourcing video QoE studies have been conducted to investigate the influence of tasks on user behavior and quality perception. Different dimensions of tasks have been applied to impaired video clips and their impact on task success, focus time, and QoE was measured. Our findings suggest that task presence or absence has no influence on the user. However, continuous tasks can improve the focus times of users, and hard tasks are suitable to filter unreliable participants.

Need for Speed? On Quality of Experience for File Storage Services. Amrehn, Philipp; Vandenbroucke, Karel; Hoßfeld, Tobias; de Moor, Katrien; Hirth, Matthias; Schatz, Raimund; Casas, Pedro. In 4th International Workshop on Perceptual Quality of Systems (PQS 2013). Vienna, Austria, 2013.

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Cloud computing has received a lot of attention within several research domains. However, there are only a few studies that focus on Quality of Experience (QoE) from a user perspective in the context of personal cloud storage services. In order to gain insights in existing use practices and to detect possible QoE influencing factors and relevant features, we conducted an online survey amongst users of personal cloud storage services and applications in general (N=349) and one specifically targeted at Dropbox users (N=49). Both studies point to accessibility, data sharing and data back-up as key features of personal cloud storage services. In addition, performance, i.e. upload and download speed, goes hand in hand with synchro-nization speed and should be taken into account when measur-ing QoE. However, cost, privacy and security related issues are as important factors as well.

@inproceedings{info3-inproceedings-2013-469,
  abstract = {Cloud computing has received a lot of attention within several research domains. However, there are only a few studies that focus on Quality of Experience (QoE) from a user perspective in the context of personal cloud storage services. In order to gain insights in existing use practices and to detect possible QoE influencing factors and relevant features, we conducted an online survey amongst users of personal cloud storage services and applications in general (N=349) and one specifically targeted at Dropbox users (N=49). Both studies point to accessibility, data sharing and data back-up as key features of personal cloud storage services. In addition, performance, i.e. upload and download speed, goes hand in hand with synchro-nization speed and should be taken into account when measur-ing QoE. However, cost, privacy and security related issues are as important factors as well.},
  address = {Vienna, Austria},
  author = {Amrehn, Philipp and Vandenbroucke, Karel and Hoßfeld, Tobias and de Moor, Katrien and Hirth, Matthias and Schatz, Raimund and Casas, Pedro},
  booktitle = {4th International Workshop on Perceptual Quality of Systems (PQS 2013)},
  keywords = {smartenit},
  month = {09},
  title = {Need for Speed? On Quality of Experience for File Storage Services},
  year = 2013
}

%0 Conference Paper
%1 info3-inproceedings-2013-469
%A Amrehn, Philipp
%A Vandenbroucke, Karel
%A Hoßfeld, Tobias
%A de Moor, Katrien
%A Hirth, Matthias
%A Schatz, Raimund
%A Casas, Pedro
%B 4th International Workshop on Perceptual Quality of Systems (PQS 2013)
%C Vienna, Austria
%D 2013
%T Need for Speed? On Quality of Experience for File Storage Services
%X Cloud computing has received a lot of attention within several research domains. However, there are only a few studies that focus on Quality of Experience (QoE) from a user perspective in the context of personal cloud storage services. In order to gain insights in existing use practices and to detect possible QoE influencing factors and relevant features, we conducted an online survey amongst users of personal cloud storage services and applications in general (N=349) and one specifically targeted at Dropbox users (N=49). Both studies point to accessibility, data sharing and data back-up as key features of personal cloud storage services. In addition, performance, i.e. upload and download speed, goes hand in hand with synchro-nization speed and should be taken into account when measur-ing QoE. However, cost, privacy and security related issues are as important factors as well.

Smart-Phone Energy Consumption Vs. 3G Signaling Load: The Influence of Application Traffic Patterns. Schwartz, Christian; Lehrieder, Frank; Wamser, Florian; Hoßfeld, Tobias; Tran-Gia, Phuoc. In Tyrrhenian International Workshop 2013 on Digital Communications: Green ICT. Genova, Italy, 2013.

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The high signaling load in today’s UMTS networks has recently lead to severe problems and network outages of several hours, so called Signaling Storms. The reason is that cer- tain network access patterns of popular smart-phone applications trigger frequent connection re-establishments, which are signaled to the network via the radio resource control (RRC) protocol. As a consequence of the network agnostic implementation of smart- phone applications, entities of the mobile network operator may experience overload, while energy consumption at the smart- phones is mutually determined. The aim of this work is to study the impact of traffic charac- teristics on the power consumption of the smart-phone and the signaling messages in the mobile network. For that purpose, we first develop a simple model for the RRC states of a smart-phone. Second, we estimate the resulting power drain and the signalling traffic of the smart-phone. Then, we investigate the applicability of our model by comparing analytical with simulation results for real-world smart-phone traffic measurements. Finally, we evaluate the effect of network parameter optimization on traffic with different statistical characteristics. Our counter-intuitive results show that in particular bursty traffic patterns are suitable for UMTS networks while periodic patterns may cause increased power consumption and signaling overload – in contrast to classical queueing systems.

@inproceedings{info3-inproceedings-2013-481,
  abstract = {The high signaling load in today’s UMTS networks has recently lead to severe problems and network outages of several hours, so called Signaling Storms. The reason is that cer- tain network access patterns of popular smart-phone applications trigger frequent connection re-establishments, which are signaled to the network via the radio resource control (RRC) protocol. As a consequence of the network agnostic implementation of smart- phone applications, entities of the mobile network operator may experience overload, while energy consumption at the smart- phones is mutually determined. The aim of this work is to study the impact of traffic charac- teristics on the power consumption of the smart-phone and the signaling messages in the mobile network. For that purpose, we first develop a simple model for the RRC states of a smart-phone. Second, we estimate the resulting power drain and the signalling traffic of the smart-phone. Then, we investigate the applicability of our model by comparing analytical with simulation results for real-world smart-phone traffic measurements. Finally, we evaluate the effect of network parameter optimization on traffic with different statistical characteristics. Our counter-intuitive results show that in particular bursty traffic patterns are suitable for UMTS networks while periodic patterns may cause increased power consumption and signaling overload – in contrast to classical queueing systems.},
  address = {Genova, Italy},
  author = {Schwartz, Christian and Lehrieder, Frank and Wamser, Florian and Hoßfeld, Tobias and Tran-Gia, Phuoc},
  booktitle = {Tyrrhenian International Workshop 2013 on Digital Communications: Green ICT},
  keywords = {oekonet},
  month = {09},
  title = {Smart-Phone Energy Consumption Vs. 3G Signaling Load: The Influence of Application Traffic Patterns},
  year = 2013
}

%0 Conference Paper
%1 info3-inproceedings-2013-481
%A Schwartz, Christian
%A Lehrieder, Frank
%A Wamser, Florian
%A Hoßfeld, Tobias
%A Tran-Gia, Phuoc
%B Tyrrhenian International Workshop 2013 on Digital Communications: Green ICT
%C Genova, Italy
%D 2013
%T Smart-Phone Energy Consumption Vs. 3G Signaling Load: The Influence of Application Traffic Patterns
%X The high signaling load in today’s UMTS networks has recently lead to severe problems and network outages of several hours, so called Signaling Storms. The reason is that cer- tain network access patterns of popular smart-phone applications trigger frequent connection re-establishments, which are signaled to the network via the radio resource control (RRC) protocol. As a consequence of the network agnostic implementation of smart- phone applications, entities of the mobile network operator may experience overload, while energy consumption at the smart- phones is mutually determined. The aim of this work is to study the impact of traffic charac- teristics on the power consumption of the smart-phone and the signaling messages in the mobile network. For that purpose, we first develop a simple model for the RRC states of a smart-phone. Second, we estimate the resulting power drain and the signalling traffic of the smart-phone. Then, we investigate the applicability of our model by comparing analytical with simulation results for real-world smart-phone traffic measurements. Finally, we evaluate the effect of network parameter optimization on traffic with different statistical characteristics. Our counter-intuitive results show that in particular bursty traffic patterns are suitable for UMTS networks while periodic patterns may cause increased power consumption and signaling overload – in contrast to classical queueing systems.

Implementation and User-centric Comparison of a Novel Adaptation Logic for DASH with SVC. Sieber, Christian; Hoßfeld, Tobias; Zinner, Thomas; Tran-Gia, Phuoc; Timmerer, Christian. In IFIP/IEEE International Workshop on Quality of Experience Centric Management (QCMan), Best Paper Award. Ghent, Belgium, 2013.

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The MPEG-DASH standard allows the client-centric access to different representations of video content via the HTTP protocol. The client can flexibly switch between different qualities, i.e., different bit rates and thus avoid waiting times during the video playback due to empty playback buffers. However, quality switches and the playback of lower qualities is perceived by the user which may reduce the Quality of Experience (QoE). Therefore, novel algorithms are required which manage the streaming behavior with respect to the user's requirements and which do not waste network resources. As indicated by recent studies, scalable video coding (SVC) may use the current network and content distribution infrastructure in a more efficient way than with single layer codecs. The contribution of this paper is the design and the implementation of a novel DASH/SVC streaming algorithm. By means of measurements in a test-bed, its performance and benefits are evaluated and compared to existing algorithms from an user-centric view point with objective performance metrics. Our findings show that the proposed algorithm outperforms other DASH mechanisms in terms of video quality, low switching frequency and usage of the available resources in a realistic mobile network scenario. This is a first step towards true QoE management of video streaming in the Internet with DASH and SVC.

@inproceedings{info3-inproceedings-2013-462,
  abstract = {The MPEG-DASH standard allows the client-centric access to different representations of video content via the HTTP protocol. The client can flexibly switch between different qualities, i.e., different bit rates and thus avoid waiting times during the video playback due to empty playback buffers. However, quality switches and the playback of lower qualities is perceived by the user which may reduce the Quality of Experience (QoE). Therefore, novel algorithms are required which manage the streaming behavior with respect to the user's requirements and which do not waste network resources. As indicated by recent studies, scalable video coding (SVC) may use the current network and content distribution infrastructure in a more efficient way than with single layer codecs. The contribution of this paper is the design and the implementation of a novel DASH/SVC streaming algorithm. By means of measurements in a test-bed, its performance and benefits are evaluated and compared to existing algorithms from an user-centric view point with objective performance metrics. Our findings show that the proposed algorithm outperforms other DASH mechanisms in terms of video quality, low switching frequency and usage of the available resources in a realistic mobile network scenario. This is a first step towards true QoE management of video streaming in the Internet with DASH and SVC.},
  address = {Ghent, Belgium},
  author = {Sieber, Christian and Hoßfeld, Tobias and Zinner, Thomas and Tran-Gia, Phuoc and Timmerer, Christian},
  booktitle = {IFIP/IEEE International Workshop on Quality of Experience Centric Management (QCMan), Best Paper Award},
  keywords = {smartenit},
  month = {05},
  title = {Implementation and User-centric Comparison of a Novel Adaptation Logic for DASH with SVC},
  year = 2013
}

%0 Conference Paper
%1 info3-inproceedings-2013-462
%A Sieber, Christian
%A Hoßfeld, Tobias
%A Zinner, Thomas
%A Tran-Gia, Phuoc
%A Timmerer, Christian
%B IFIP/IEEE International Workshop on Quality of Experience Centric Management (QCMan), Best Paper Award
%C Ghent, Belgium
%D 2013
%T Implementation and User-centric Comparison of a Novel Adaptation Logic for DASH with SVC
%X The MPEG-DASH standard allows the client-centric access to different representations of video content via the HTTP protocol. The client can flexibly switch between different qualities, i.e., different bit rates and thus avoid waiting times during the video playback due to empty playback buffers. However, quality switches and the playback of lower qualities is perceived by the user which may reduce the Quality of Experience (QoE). Therefore, novel algorithms are required which manage the streaming behavior with respect to the user's requirements and which do not waste network resources. As indicated by recent studies, scalable video coding (SVC) may use the current network and content distribution infrastructure in a more efficient way than with single layer codecs. The contribution of this paper is the design and the implementation of a novel DASH/SVC streaming algorithm. By means of measurements in a test-bed, its performance and benefits are evaluated and compared to existing algorithms from an user-centric view point with objective performance metrics. Our findings show that the proposed algorithm outperforms other DASH mechanisms in terms of video quality, low switching frequency and usage of the available resources in a realistic mobile network scenario. This is a first step towards true QoE management of video streaming in the Internet with DASH and SVC.

Pippi Longstocking Calculus for Temporal Stimuli Pattern on YouTube QoE. Hoßfeld, Tobias; Strohmeier, Dominik; Raake, Alexander; Schatz, Raimund. In 5th ACM Workshop on Mobile Video (MoVid 2013). Oslo, Norway, 2013.

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Video streaming over wireless broadband is currently re- sponsible for half of the world-wide mobile data traffic and its share is expected to even further increase. Therefore, mobile operators need to understand how Quality of Ex- perience (QoE) of mobile video streaming is impacted by through the network delivery. Due to HTTP video stream- ing used by video portals like YouTube or NetFlix, problems or insufficient resources in the networks manifest as stalling events during service consumption on an end user device. In this paper, we discuss the challenges for QoE monitoring for HTTP-based mobile video regarding three aspects. First, the impact of different patterns in terms of stalling event frequency and length on QoE is quantified on behalf of a study on YouTube. Second, we evaluate predictive power of aggregate measures like total stalling time. Third, we discuss the resulting consequences and challenges for mobile video QoE modeling, monitoring and provisioning.

@inproceedings{info3-inproceedings-2013-459,
  abstract = {Video streaming over wireless broadband is currently re- sponsible for half of the world-wide mobile data traffic and its share is expected to even further increase. Therefore, mobile operators need to understand how Quality of Ex- perience (QoE) of mobile video streaming is impacted by through the network delivery. Due to HTTP video stream- ing used by video portals like YouTube or NetFlix, problems or insufficient resources in the networks manifest as stalling events during service consumption on an end user device. In this paper, we discuss the challenges for QoE monitoring for HTTP-based mobile video regarding three aspects. First, the impact of different patterns in terms of stalling event frequency and length on QoE is quantified on behalf of a study on YouTube. Second, we evaluate predictive power of aggregate measures like total stalling time. Third, we discuss the resulting consequences and challenges for mobile video QoE modeling, monitoring and provisioning.},
  address = {Oslo, Norway},
  author = {Hoßfeld, Tobias and Strohmeier, Dominik and Raake, Alexander and Schatz, Raimund},
  booktitle = {5th ACM Workshop on Mobile Video (MoVid 2013)},
  keywords = {demobenefit},
  month = {02},
  title = {Pippi Longstocking Calculus for Temporal Stimuli Pattern on YouTube QoE},
  year = 2013
}

%0 Conference Paper
%1 info3-inproceedings-2013-459
%A Hoßfeld, Tobias
%A Strohmeier, Dominik
%A Raake, Alexander
%A Schatz, Raimund
%B 5th ACM Workshop on Mobile Video (MoVid 2013)
%C Oslo, Norway
%D 2013
%T Pippi Longstocking Calculus for Temporal Stimuli Pattern on YouTube QoE
%X Video streaming over wireless broadband is currently re- sponsible for half of the world-wide mobile data traffic and its share is expected to even further increase. Therefore, mobile operators need to understand how Quality of Ex- perience (QoE) of mobile video streaming is impacted by through the network delivery. Due to HTTP video stream- ing used by video portals like YouTube or NetFlix, problems or insufficient resources in the networks manifest as stalling events during service consumption on an end user device. In this paper, we discuss the challenges for QoE monitoring for HTTP-based mobile video regarding three aspects. First, the impact of different patterns in terms of stalling event frequency and length on QoE is quantified on behalf of a study on YouTube. Second, we evaluate predictive power of aggregate measures like total stalling time. Third, we discuss the resulting consequences and challenges for mobile video QoE modeling, monitoring and provisioning.

Internet Video Delivery in YouTube: From Traffic Measurements to Quality of Experience. Hoßfeld, Tobias; Schatz, Raimund; Biersack, Ernst; Plissonneau, Louis. In Data Traffic Monitoring and Analysis: From measurement, classification and anomaly detection to Quality of experience, C. C. Ernst Biersack (ed.). Springer’s Computer Communications and Networks series, Volume 7754, 2013.

[ Abstract ]
[ BibTeX ]
[ EndNote ]

This chapter investigates HTTP video streaming over the Internet for the YouTube platform. YouTube is used as concrete example and case study for video delivery over the Internet, since it is not only the most popular online video platform, but also generates a large share of traffic on today’s Internet. We will describe the YouTube infrastructure as well as the underlying mechanisms for optimizing content delivery. Such mechanisms include server selection via DNS as well as application-layer traffic management. Furthermore, the impact of delivery via the Internet on the user experienced quality (QoE) of YouTube video streaming is quantified. In this context, different QoE monitoring approaches are qualitatively compared and evaluated in terms of the accuracy of QoE estimation.

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

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

From Packets to People: Quality of Experience as New Measurement Challenge. Schatz, Raimund; Hoßfeld, Tobias; Janowski, Lucjan; Egger, Sebastian. In Data Traffic Monitoring and Analysis: From measurement, classification and anomaly detection to Quality of experience, C. C. Ernst Biersack (ed.). Springer’s Computer Communications and Networks series, Volume 7754, 2013.

[ Abstract ]
[ BibTeX ]
[ EndNote ]

Over the course of the last decade, the concept of Quality of Experience (QoE) has gained strong momentum, both from an academic research and an industry perspective. Being linked very closely to the subjective perception of the end user, QoE is supposed to enable a broader, more holistic understanding of the qualitative performance of networked communication systems and thus to complement the traditional, more technology-centric Quality of Service (QoS) perspective. The purpose of this chapter is twofold: firstly, it introduces the reader to QoE by discussing the origins and the evolution of the concept. Secondly, it provides an overview of the current state of the art of QoE research, with focus on work that particularly addresses QoE as a measurement challenge on the technology as well as on the end-user level. This is achieved by surveying the different streams of QoE research that have emerged in the context of Video, Voice and Web services with respect to the following aspects: fundamental relationships and perceptual principles, QoE assessment, modeling and monitoring.

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

%0 Book Section
%1 info3-incollection-2013-19
%A Schatz, Raimund
%A Hoßfeld, Tobias
%A Janowski, Lucjan
%A Egger, Sebastian
%B Data Traffic Monitoring and Analysis: From measurement, classification and anomaly detection to Quality of experience
%D 2013
%E Ernst Biersack, Christian Callegari
%I Springer’s Computer Communications and Networks series, Volume 7754
%T From Packets to People: Quality of Experience as New Measurement Challenge
%X Over the course of the last decade, the concept of Quality of Experience (QoE) has gained strong momentum, both from an academic research and an industry perspective. Being linked very closely to the subjective perception of the end user, QoE is supposed to enable a broader, more holistic understanding of the qualitative performance of networked communication systems and thus to complement the traditional, more technology-centric Quality of Service (QoS) perspective. The purpose of this chapter is twofold: firstly, it introduces the reader to QoE by discussing the origins and the evolution of the concept. Secondly, it provides an overview of the current state of the art of QoE research, with focus on work that particularly addresses QoE as a measurement challenge on the technology as well as on the end-user level. This is achieved by surveying the different streams of QoE research that have emerged in the context of Video, Voice and Web services with respect to the following aspects: fundamental relationships and perceptual principles, QoE assessment, modeling and monitoring.

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.

Research Project initiated and financed by	ÖkoNet Project Team
	Heads	Florian Wamser,
		Tobias Hoßfeld
	Researchers	Valentin Burger,
		Matthias Hirth,
		Frank Lehrieder,
		Christian Schwartz

ÖkoNet: Design and Performance Evaluation of New Mechanisms for the Future Internet – New Paradigms and Economic Aspects

ÖkoNet Project Team

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