Tiago Gasiba
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IEEE Transactions on Broadcasting | 2007
Michael G. Luby; Tiago Gasiba; Thomas Stockhammer; Mark Watson
Raptor codes have been standardized as application layer forward error correction (FEC) codes for Multimedia Broadcast and Multicast Services (MBMS) and Digital Video Broadcast (DVB) due to their extraordinary advanced FEC protection and performance. Raptor codes are known to have characteristics very close to ideal and provide a wide range of operating flexibility and efficiency unmatched by other codes, and in particular they are an excellent implementation of fountain codes. Until now, investigations of the application of Raptor codes to UMTS and EPGRS have used an overall system model that does not accurately model the physical channel and user mobility, simplistically assuming independent random packet losses at the application layer. We investigate MBMS in UMTS in a much more realistic and complete simulation environment by considering advanced and complete channel models that simulate the physical channel and user mobility in a cellular network. We use this realisitic simulation environment to determine optimal system parameters under different mobility models, with different bearer parameters, and without and with selective combining. More specifically, we investigate joint settings of the Raptor code rate, the Turbo code rate, transmission power, etc., to find settings which provide reliable download delivery of files using minimal transmission energy. One of our main results is that optimal system-wide operating points use low transmission power and a modest amount of Turbo coding that results in relatively large radio packet loss rates that is compensated for by using a substantial amount of Raptor coding. These optimal operating points use far less transmission energy for download delivery of files than possible operating points without Raptor
consumer communications and networking conference | 2006
M. Luby; M. Watson; Tiago Gasiba; T. Stockhammer; Wen Xu
In this work we address reliablefile delivery over mobile broadcast networks, concentrating on the Raptor codes as specified for Multimedia Broadcast/Multicast Services (MBMS) within 3GPP. We start by describing Luby-Transform (LT) codes, which are the first practical fountain codes. Then, using a natural and easy to understand linear algebra notation, we describe Raptor codes as a powerful extension of LT codes. We provide some insight into the Raptor code structure and some guidelines for implementation of encoders and decoders. Finally, some selected simulations verify the good performance of file distribution with Raptor codes as specified in 3GPP. References to a complete set of simulation results are also provided. I. INTRODUCTION
Journal of Multimedia | 2006
Junaid Afzal; Thomas Stockhammer; Tiago Gasiba; Wen Xu
Recently, Multimedia Broadcast Multicast Service (MBMS) has been specified by 3GPP as a Release 6 feature in order to meet the increasing demands of multimedia download and streaming applications in mobile scenarios. H.264, as the unique recommended video codec for MBMS, serves as an essential component because of its high compression efficiency and easy network integration capability. In this study, we introduce and analyze the main system design parameters that influence the performance of the H.264 encoded video streaming over EGPRS and UMTS bearers. Effective design methodology including robustness against packet losses and efficient use of the scarce radio resources is presented. Care is taken on the processing power of mobiles, service delay constraints, and heterogeneous receiving conditions. Then, we investigate application of an advanced receiver concept, the so-called permeable layer receiver, in MBMS video broadcasting environments. Selected simulation results show the suitability of certain parameter selection as well as the benefits provided by the advanced receiver concept. Finally, a real-time test bed for MBMS called RealNeS-MBMS is presented. With this tool, a standard-compliant GERAN network can be simulated and the system design procedure including H.264 based video broadcast streaming can be evaluated in real-time.
mobile and ubiquitous multimedia | 2006
Michael G. Luby; Mark Watson; Tiago Gasiba; Thomas Stockhammer
Third Generation Partnership Project (3GPP) and Digital Video Broadcasting (DVB) have just recently specified the use Raptor codes in their mobile broadcast file delivery engine. Until today, investigations of the applicability of these codes to the mentioned systems have been carried out by assuming almost exclusively quite simple loss models such as statistically independent radio packet losses. Furthermore, the combination and tradeoffs between physical layer parameters such as transmit power or physical layer for-ward error correction code rates in system design has been completely ignored. In this work we investigate the end-to-end system performance by analyzing the trade-off between physical layer parameters and application layer code. In particular we are interested in determining the optimal system operating points for optimized broadcast file delivery. Parameters such as power allocation, mobility model, physical layer Turbo code rate, raptor code expansion ratio are investigated and a single performance criteria is defined, namely the required energy to deliver a file to at least some high percentage of users. It is shown that typically considered system configurations with high transmit power and low physical layer code rates - resulting in low radio block loss rates - are in general suboptimal for efficient delivery. A careful tradeoff the system parameters can reduce the required resources in the order of a magnitude.
international conference on communications | 2006
Tiago Gasiba; Thomas Stockhammer; Junaid Afzal; Wen Xu
Raptor codes have been recently standardized by 3GPP to be used in the application layer. These codes are very efficient and perform sufficiently close to the so-called ideal fountain code on the block-erasure channel. However, for real applications, a simple receiver enhancement called permeable layer receiver can be done, which provides huge performance gains. Standard Raptor decoding algorithms have to be revised and new efficient decoding algorithms need to be introduced. In this work we present a practical and efficient implementation of the Raptor decoder for permeable layer receiver. We show that, not only we achieve huge performance gains, but we achieve them at an affordable (low) decoding complexity. Complexity and decoding performance simulation results are presented for the download delivery and video broadcasting.
communications and mobile computing | 2007
Thomas Stockhammer; Tiago Gasiba; Wissam Abdel Samad; Thomas Schierl; Hrvoje Jenkac; Thomas Wiegand; Wen Xu
The integration of reliable Video-on-Demand (VoD) broadcasting schemes in mobile datacast systems, specifically in DVB-H, is studied and enhanced. Sophisticated VoD broadcasting schemes such as Harmonic Broadcasting (HB) allows receivers to tune into the ongoing transmission of a video stream at arbitrary time, while still being able to receive the multimedia sequence from beginning to end, after short initial playout latency. In addition, we address service enhancements by using scalable video coding (SVC) to support heterogeneous receiver capabilities and receiving conditions as well as the reception of the signal from more than on transmission site. We present and discuss options for the integration of VoD broadcasting schemes in combination with fountain codes. Optimizations in parameter selection are discussed. A realistic protocol environment is only slightly modified to support our system concept. Simulation results show the benefits of the discussed VoD scheme compared to existing approaches if integrated in DVB-H.
consumer communications and networking conference | 2006
Junaid Afzal; Thomas Stockhammer; Tiago Gasiba; Wen Xu
GPP has specified Multimedia Broadcast/Multicast Services (MBMS) addressing the increasing demands of multi- media download and streaming applications in mobile scenarios. Thereby, video coding is an essential component and H.264 is the only recommended video codec in MBMS mainly due to its high compression efficiency and easy network integration. In this paper we introduce the main system design parameters that influence the performance of MBMS video streaming over EG- PRS and UMTS using H.264 encoded streaming. Effective design methodology that includes robustness against packet losses and efficient use of the scarce radio resources is presented. Thereby, care is taken also about the limited processing power of mobile terminals, service delay constraints, and heterogeneous receiving conditions. We also investigate an advanced receiver concept, the so called permeable-layer receiver. Selected simulation results show the suitability of certain parameter settings as well as the benefits provided by the advanced receiver concept.
international conference on mobile multimedia communications | 2006
Thomas Stockhammer; Tiago Gasiba; Wissam Abdel Samad; Wen Xu; Hrvoje Jenkac; Thomas Schierl
The integration of reliable Video-on-Demand (VoD) broadcasting schemes in mobile datacast systems, specifically in DVB-h, is studied and enhanced. Sophisticated VoD broadcasting schemes such as Harmonic Broadcasting (HB) allow receivers to tune into the ongoing transmission of a video-stream at arbitrary time, while still being able to receive the multimedia sequence from beginning to end, after short initial playout latency. In addition, we address service enhancements by using scalable video coding (SVC) to support heterogeneous receiver capabilities and receiving conditions as well as signal reception from multiple transmission sites. We present and discuss options for the integration of VoD broadcasting schemes in combination with fountain codes. Optimizations in parameter selection are introduced. A realistic protocol environment is only slightly modified to support our system concept. Simulation results show the benefits of the discussed VoD scheme compared to existing approaches if integrated in DVB-h.
personal, indoor and mobile radio communications | 2005
Wen Xu; Tiago Gasiba; Thomas Stockhammer; Hrvoje Jenkac; Günther Liebl
Various advanced methods have been proposed to achieve sufficiently high throughput as well as reliability for multimedia broadcast multicast services (MBMS) within 3GPP RAN and GERAN. One of the methods which yield promising results with only marginal system modifications is based on outer Reed-Solomon (RS) coding on the radio link control (RLC) layer. For initial studies standard decoding algorithms based on erasure-only decoders have been employed. In order to further improve the performance, the system can be viewed as a serially concatenated code such that iterative decoding can be performed. Then, advanced receivers for MBMS over GERAN would incorporate soft-in soft-cut (SISO) decoders for both the inner convolutional code, as well as the outer RS code. Whereas for the convolutional code, standard SISO algorithms are applied, for the outer RS code a standard Berlekamp-Massey algorithm is modified to accept soft-input and to provide soft-output. With this modified iterative decoding strategy, simulations have shown gains of up to 14% in throughput on typical mobile radio channels
Handbook of Mobile Broadcasting: DVB-H, DMB, ISDB-T and Media FLO | 2008
Thomas Stockhammer; Amin Shokrollahi; Mark Watson; Michael G. Luby; Tiago Gasiba