Downlink Packet Scheduling and Resource Allocation for Multiuser Video Transmission Over Wireless NetworksPublic Deposited
Video transmission over wireless networks to multiple mobile users has remained a challenging problem due to potential limitations on bandwidth and the time-varying nature of wireless channels. Recent advances in wireless access technologies, such as, HSDPA and IEEE 802.16, are targeted at achieving higher throughput over wireless networks. Meanwhile, advances in video compression, such as the recently developed H.264/AVC standard as well as scalable video coding schemes aim to provide more efficient video compression as well as increased adaptability to dynamic channel and network conditions. This dissertation aims to benefit from the improving wireless access technologies and video compression standards by presenting cross-layer optimized packet scheduling schemes for the streaming of multiple pre-encoded video streams over wireless downlink packet access networks. A gradient based scheduling scheme is presented in which user data rates are dynamically adjusted based on channel quality as well as the gradients of a utility function. The user utilities are designed as a function of the distortion of the received video. This enables distortion-aware packet scheduling both within and across multiple users. In the case of lossy channels with random packet losses, the utility functions are derived based on the expected distortion of the decoded video at the receiver. The utility takes into account decoder error concealment, an important component in deciding the received quality of the video. Both simple and complex decoder error concealment techniques are investigated. Simulation results show that the gradient based scheduling framework combined with the content-aware utility functions provide a viable method for downlink packet scheduling as it can significantly outperform current content-independent techniques. Further tests determine the sensitivity of the system to the initial video encoding schemes, as well as to non-real-time packet ordering techniques. Comparisons are also made between scalable and conventional video coding techniques under the proposed schemes.