Rate-control for retransmission-based video transport over wireless channels

We consider the scenario of using the Automatic Repeat reQuest (ARQ) retransmission scheme for two-way video communications over wireless Rayleigh fading channels. Video quality and the end-to-end delay are the major concerns of these application. For low end-to-end delay, a short packet-size and a low-delay video rate-control scheme like the one in TMN8 can be used. During the retransmissions of error packets, due to the reduced channel throughput and the video encoder buffer fill-up, the video encoder rate-control algorithm may significantly reduce the bits allocated to each video frame or skip frames. This may cause poor video quality or result in jerky motion. In this paper we investigate the impact of video quality due to retransmission and propose improved race-control schemes which take into consideration the effects of the video buffer fill-up, an a priori channel model, and the channel feedback information. Simulation results showing the improvement over TMN8 are also presented.