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Papers by Thomas Stockhammer

IEEE Transactions on Broadcasting, 2022

International Conference on Telecommunications, Jun 8, 2009

IPTV services have been widely deployed by network operators around the world over the last years... more IPTV services have been widely deployed by network operators around the world over the last years. Real-time streaming of Linear TV and Video-on-Demand (VoD) offerings, especially in the now more and more popular High Definition quality, however puts a high burden on the network and content servers concerning bandwidth, Quality-of-Service, processing performance and scalability if 100.000 s of user have to be supported simultaneously. While multicast delivery can cope with some of these problems for Linear TV services, the unicast VoD services cannot take advantage of that and especially the request for on-demand content is expected to substantially grow in the future. With the introduction of Content Download Services (CDSs), operators now have the option to provide IPTV services in innovative ways: They can provide high-quality video services to users with limited access bandwidth, offload the streaming request for blockbuster movies at peak times from the VoD servers or provided personalized advertisements for insertion into a live program event in advance to the users set-top box. The Digital Video Broadcast (DVB) Project has recently finalized its CDS specification. DVB CDS supports push and pull delivery models with unicast, multicast and peer-to-peer distribution to enable various business models and use cases. In this work we introduce the standardized technology, its architecture and map it to the use cases and business models.

MPEG DASH provides formats that are suitable to stream media content over HTTP. Typically, the DA... more MPEG DASH provides formats that are suitable to stream media content over HTTP. Typically, the DASH client adaptively requests small chunks of media based on the available bandwidth and other resources. This client-pull technology has proven to be more flexible, firewall-friendly and CDN-scalable than server-push technologies. However, service providers have less control given the decentralized and client-driven nature of DASH, which introduces new challenges for them to offer a consistent and possibly higher quality of service for premium users. This issue is addressed by MPEG in a new work referred to as SAND: Server and Networkassisted DASH. The key features of SAND are asynchronous network-to-client and network-to-network communication, and the exchange of quality-related assisting information in such a way that it does not delay or interfere with the delivery of the streaming media content. MPEG is expected to publish and complete the work on SAND as a new part of the MPEG DASH standard by early 2016.

IEEE Transactions on Circuits and Systems for Video Technology, Jul 1, 2003

IST Mobile and Wireless Communications Summit, 2006

The service layer of LTE Broadcast is designed to broadcast formats that are commonly used in Ove... more The service layer of LTE Broadcast is designed to broadcast formats that are commonly used in Over-The-Top Video Streaming, in particular DASH-formats. Whereas the initial deployments may focus on broadcast only modes, the design of using and combining OTT formats with broadcast distributions enables new opportunities and services in terms of combining broadcast distribution with OTT video services. These new features are discussed and progressed in 3GPP MBMS and ATSC3.0 in order provide the ability to distribute TV-centric content efficiently to a wide variety of devices including mobile phones, tablets and in-car receivers. This design enables a new use cases such as hybrid delivery, broadcast coverage extensions or MBMS On-Demand. The document provides insights into the architectures and technical details as defined in 3GPP. It will also provide examples on how LTE Broadcast service layer can be used in order to fulfill advanced and innovative use cases as discussed above. The final presentation will be supported by selected simulation results in order to show the benefits of the approach.

ABSTRACT This contribution addresses the case when live packet-switched video is used to enrich c... more ABSTRACT This contribution addresses the case when live packet-switched video is used to enrich circuit-switched speech calls in mobile telephony. Circuit-switched and packet-switched transmissions generally operate on completely different transmission paths resulting in different QoS in terms of delay and loss rates. In this case, video and audio data recorded at the same time are not multiplexed together and might arrive at completely different time instances at the receiver. This is a major challenge for the receiver and the service as lip synchronicity between the voice and the video can generally not be expected. Our presented method solves the synchronization problem purely by the use of signal processing, i.e. no inclusion of time stamps is needed. The method is simple to implement and it is able to handle signal disturbances over the link.

An adaptive error protection scheme for embedded source coders is presented. Convolutional codes ... more An adaptive error protection scheme for embedded source coders is presented. Convolutional codes of very high memory and regressive redundancy are applied to encode the data frame of the source. The channel decoder with scalable complexity and delay employs modified sequential decoding. In contrast to conventional coding systems, the principal idea of this new algorithm, the `far end error decoder

Multimedia Signal Processing, 2004

Kluwer Academic Publishers eBooks, Feb 24, 2006

We will present a new model for wireless packet erasure channels, which can be used for both theo... more We will present a new model for wireless packet erasure channels, which can be used for both theoretical analysis and real-time simulation of network protocol performance. The correlation between successive packet losses will be described by a higher-order Markov process, which can be transformed into an equivalent first-order Markov chain, such that all major performance measures can be derived from

ABSTRACT In this paper different means for adding reliability in different protocol layers are di... more ABSTRACT In this paper different means for adding reliability in different protocol layers are discussed, in order to reliably broadcast multimedia data within existing wireless networks. In particular, we investigate the performance of additional forward error correction in the physical layer, the radio link control layer, and the RTP layer for multimedia broadcast and multicast services over GERAN systems. Advantages and drawbacks when applying means for reliability in different layers are shown. We introduce a simple receiver modification, referred to as permeable-layer receiver (PLR), which exploits traditionally useless information at the receiver, while the transmitter is kept unchanged. Significant performance gains are reported. Finally, the application to H.264/AVC based wireless video broadcast is discussed and the performance of different system designs for video transmission is shown

EURASIP Journal on Advances in Signal Processing, Apr 20, 2006

ABSTRACT This paper proposes an adaptive HTTP-based video streaming framework for mobile networks... more ABSTRACT This paper proposes an adaptive HTTP-based video streaming framework for mobile networks using the Scalable Video Coding (SVC) extension to the H.264 standard. We present a method to statistically estimate the channel at the mobile client and use it in our work to adapt the bit rate of the video. The adaptation takes into account both the quality contributions and the probability of successful timely decoding for different video segments. The simulation results show significant improvements in terms of a reduction of playback interruptions and improved perceived quality of service.

IEEE Transactions on Broadcasting, 2022

International Conference on Telecommunications, Jun 8, 2009

IPTV services have been widely deployed by network operators around the world over the last years... more IPTV services have been widely deployed by network operators around the world over the last years. Real-time streaming of Linear TV and Video-on-Demand (VoD) offerings, especially in the now more and more popular High Definition quality, however puts a high burden on the network and content servers concerning bandwidth, Quality-of-Service, processing performance and scalability if 100.000 s of user have to be supported simultaneously. While multicast delivery can cope with some of these problems for Linear TV services, the unicast VoD services cannot take advantage of that and especially the request for on-demand content is expected to substantially grow in the future. With the introduction of Content Download Services (CDSs), operators now have the option to provide IPTV services in innovative ways: They can provide high-quality video services to users with limited access bandwidth, offload the streaming request for blockbuster movies at peak times from the VoD servers or provided personalized advertisements for insertion into a live program event in advance to the users set-top box. The Digital Video Broadcast (DVB) Project has recently finalized its CDS specification. DVB CDS supports push and pull delivery models with unicast, multicast and peer-to-peer distribution to enable various business models and use cases. In this work we introduce the standardized technology, its architecture and map it to the use cases and business models.

MPEG DASH provides formats that are suitable to stream media content over HTTP. Typically, the DA... more MPEG DASH provides formats that are suitable to stream media content over HTTP. Typically, the DASH client adaptively requests small chunks of media based on the available bandwidth and other resources. This client-pull technology has proven to be more flexible, firewall-friendly and CDN-scalable than server-push technologies. However, service providers have less control given the decentralized and client-driven nature of DASH, which introduces new challenges for them to offer a consistent and possibly higher quality of service for premium users. This issue is addressed by MPEG in a new work referred to as SAND: Server and Networkassisted DASH. The key features of SAND are asynchronous network-to-client and network-to-network communication, and the exchange of quality-related assisting information in such a way that it does not delay or interfere with the delivery of the streaming media content. MPEG is expected to publish and complete the work on SAND as a new part of the MPEG DASH standard by early 2016.

IEEE Transactions on Circuits and Systems for Video Technology, Jul 1, 2003

IST Mobile and Wireless Communications Summit, 2006

The service layer of LTE Broadcast is designed to broadcast formats that are commonly used in Ove... more The service layer of LTE Broadcast is designed to broadcast formats that are commonly used in Over-The-Top Video Streaming, in particular DASH-formats. Whereas the initial deployments may focus on broadcast only modes, the design of using and combining OTT formats with broadcast distributions enables new opportunities and services in terms of combining broadcast distribution with OTT video services. These new features are discussed and progressed in 3GPP MBMS and ATSC3.0 in order provide the ability to distribute TV-centric content efficiently to a wide variety of devices including mobile phones, tablets and in-car receivers. This design enables a new use cases such as hybrid delivery, broadcast coverage extensions or MBMS On-Demand. The document provides insights into the architectures and technical details as defined in 3GPP. It will also provide examples on how LTE Broadcast service layer can be used in order to fulfill advanced and innovative use cases as discussed above. The final presentation will be supported by selected simulation results in order to show the benefits of the approach.

ABSTRACT This contribution addresses the case when live packet-switched video is used to enrich c... more ABSTRACT This contribution addresses the case when live packet-switched video is used to enrich circuit-switched speech calls in mobile telephony. Circuit-switched and packet-switched transmissions generally operate on completely different transmission paths resulting in different QoS in terms of delay and loss rates. In this case, video and audio data recorded at the same time are not multiplexed together and might arrive at completely different time instances at the receiver. This is a major challenge for the receiver and the service as lip synchronicity between the voice and the video can generally not be expected. Our presented method solves the synchronization problem purely by the use of signal processing, i.e. no inclusion of time stamps is needed. The method is simple to implement and it is able to handle signal disturbances over the link.

An adaptive error protection scheme for embedded source coders is presented. Convolutional codes ... more An adaptive error protection scheme for embedded source coders is presented. Convolutional codes of very high memory and regressive redundancy are applied to encode the data frame of the source. The channel decoder with scalable complexity and delay employs modified sequential decoding. In contrast to conventional coding systems, the principal idea of this new algorithm, the `far end error decoder

Multimedia Signal Processing, 2004

Kluwer Academic Publishers eBooks, Feb 24, 2006

We will present a new model for wireless packet erasure channels, which can be used for both theo... more We will present a new model for wireless packet erasure channels, which can be used for both theoretical analysis and real-time simulation of network protocol performance. The correlation between successive packet losses will be described by a higher-order Markov process, which can be transformed into an equivalent first-order Markov chain, such that all major performance measures can be derived from

ABSTRACT In this paper different means for adding reliability in different protocol layers are di... more ABSTRACT In this paper different means for adding reliability in different protocol layers are discussed, in order to reliably broadcast multimedia data within existing wireless networks. In particular, we investigate the performance of additional forward error correction in the physical layer, the radio link control layer, and the RTP layer for multimedia broadcast and multicast services over GERAN systems. Advantages and drawbacks when applying means for reliability in different layers are shown. We introduce a simple receiver modification, referred to as permeable-layer receiver (PLR), which exploits traditionally useless information at the receiver, while the transmitter is kept unchanged. Significant performance gains are reported. Finally, the application to H.264/AVC based wireless video broadcast is discussed and the performance of different system designs for video transmission is shown

EURASIP Journal on Advances in Signal Processing, Apr 20, 2006

ABSTRACT This paper proposes an adaptive HTTP-based video streaming framework for mobile networks... more ABSTRACT This paper proposes an adaptive HTTP-based video streaming framework for mobile networks using the Scalable Video Coding (SVC) extension to the H.264 standard. We present a method to statistically estimate the channel at the mobile client and use it in our work to adapt the bit rate of the video. The adaptation takes into account both the quality contributions and the probability of successful timely decoding for different video segments. The simulation results show significant improvements in terms of a reduction of playback interruptions and improved perceived quality of service.