Distortion-optimized video encoding and streaming in multi-rate wireless lans

In this paper, we present a cross-layer methodology for video streaming in wireless LANs that employs joint source coding and rate adaptation at the wireless physical layer (PHY). More specifically, we investigate the impact of adapting the PHY transmission rate, and thus changing the throughput and packet loss channel characteristics, on the rate-distortion (RD) performance of a transmitted video sequence. We develop an algorithm that jointly optimizes source coding, application-layer channel coding, and the PHY rate adaptation. Simulation results obtained with the H.264/AVC codec, demonstrate video quality improvements when compared with a system that employs PHY rate adaptation independently from the application layer.