| Summary: | This thesis addresses different aspects of wireless video transmission of scalable video content to multiple users over lossy and under-provisioned channels. Modern wireless video transmission systems, such as the Third Generation Partnership Project (3GPP)'s high speed packet access (HSPA) networks and IEEE 802.11-based wireless local area networks (WLANs) allow sharing common bandwidth resources among multiple video users. However, the unreliable nature of the wireless link results in packet losses and fluctuations in the available channel capacity. This calls for flexible encoding, error protection, and rate control strategies implemented at the video encoder or base station.
The scalable video coding (SVC) extension of the H.264/AVC video standard delivers quality scalable video bitstreams that help define and provide quality of service (QoS) guarantees for wireless video transmission applications. We develop real-time rate and distortion estimation models for the coarse/medium granular scalability (CGS/MGS) features in SVC. These models allow mobile video encoders to predict the packet size and corresponding distortion of a video frame using only the residual mean absolute difference (MAD) and the quantization parameter (QP).
This thesis employs different cross layer resource allocation techniques that jointly optimize the video bit-rate, error protection, and latency control algorithms in pre-encoded and real-time streaming scenarios. In the first scenario, real-time multi-user streaming with dynamic channel throughput and packet losses is solved by controlling the base and enhancement layer quality as well as unequal erasure protection (UXP) overhead to minimize the frame-level distortion. The second scenario considers pre-encoded scalable video streaming in capacity limited wireless channels suffering from latency problems and packet losses. We develop a loss distortion model for hierarchical predictive coders and employ dynamic UXP allocation with a delay-aware non-stationary rate-allocation streaming policy. The third scenario addresses the problem of efficiently allocating multi-rate IEEE 802.11-based network resources among multiple scalable video streams using temporal fairness constraints. We present a joint link-adaptation at the physical (PHY) layer and a dynamic packet dropping mechanism in the network or medium access control (MAC) layer for multi-rate wireless networks. We demonstrate that these methods result in significant performance gains over existing schemes.
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