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We propose a dynamic sharing of radio resources in a wireless multiuser system by combining a flexible video coding scheme, namely the currently developed scalable video coding (SVC) extension of H.264/AVC with appropriate radio link buffer management for multiuser streaming services. The paper introduces the components of the proposed system and the used cross-layer interface. Simulation results verify the benefits of our approach.

In this paper we compare strategies for joint radio link buffer management and scheduling for wireless video streaming. Based on previous work in this area [8], we search for an optimal combination of scheduler and drop strategy for different end-to-end streaming options including timestamp-based streaming and ahead-of-time streaming, both with variable initial playout delay. We will show that a performance gain versus the two best drop strategies in Liebl et al. [8], i.e. drop the HOL packet or drop the packet with the lowest priority starting from HOL, is possible: Provided that some basic side-information on the structure of the incoming video stream is available, a more sophisticated drop strategy removes packets from an HOL group of packets in such a way that the temporal dependencies usually present in video streams are not violated. This advanced buffer management scheme yields significant improvements for almost all investigated scheduling algorithms and streaming options. In addition, we will demonstrate the importance of fairness among users when selecting a suitable scheduler, especially if ahead-of-time streaming is to be applied: Given a reasonable initial playout delay at the streaming media client, both the overall achievable quality averaged over all users, as well as the individual quality of users with bad channel conditions can be increased significantly by trading off fairness with maximum throughput of the system.

In this work we show the suitability of H.264/MPEG-4 AVC extended profile for wireless video streaming applications. In particular, we exploit the advanced bit stream switching capabilities using SP/SI pictures defined in the H.264/MPEG-4 AVC standard. For both types of switching pictures, optimized encoders are developed. We introduce a framework for dynamic switching and frame scheduling. For this purpose we define an appropriate abstract representation for media encoded for video streaming, as well as for the characteristics of wireless variable bit rate channels. The achievable performance gains over H.264/MPEG-4 AVC with constant bit rate (CBR) encoding are shown for wireless video streaming over enhanced GPRS (EGPRS).