Robust video streaming over wireless LANs using multiple description transcoding and prioritized retransmission

Video transport over wireless Local Area Networks (LANs) usually suffers from signal fading, noise interference, and network congestion, leading to time-varying packet loss rate and fluctuating effective bandwidth. We propose in this paper an adaptive error control scheme to adaptively insert error-resilience features into a compressed video in the media gateway which serves roaming clients. Our scheme divides the error control operation into the single description (SD) and multiple-description (MD) modes according to channel condition estimation. In the SD mode, a content-based prioritized retransmission method is proposed to mitigate the error propagation due to packet loss in video transport over wireless LANs. The proposed prioritized retransmission scheme determines the retransmission schedule of a lost packet according to the packet's loss impact that is obtained in a front-end encoding process. In the MD mode, we propose a channel-aware MD transcoding method to take advantage of MD coding and path diversity so as to further mitigate the error propagation due to packet loss caused by transient channel switching while roaming in wireless LANs. Experimental results show that the proposed scheme effectively mitigates the error propagation due to packet loss, while maintaining low extra computational complexity and low overhead cost. The proposed method is suitable for realtime streaming of prestored videos. (c) 2007 Elsevier Inc. All rights reserved.