A novel hybrid ARQ algorithm for real-time video transport over wireless LAN

In this paper, we propose a modified MAC protocol supporting real-time video traffic over the IEEE 802.11 WLAN. Investigating H.26L real-time video transmission over wireless IEEE 802.11b LANs, we present a novel hybrid automatic repeat request (ARQ) algorithm that efficiently combines forward error control (EEC) coding with the ARQ protocol based on multiple transmission stages. The scheme includes: (1) multiple transmission stages with corresponding ARQ feedback information that determines how many transmission stages should be activated; (2) conditional frame skipping algorithm based on accumulated feedback information. Through analysis and simulation, we show that multiple-stages based Hybrid ARQ scheme has high error recovery rate for real-time video frames. In case of severe unreliable channel which causes losing a lot of IP packets, at the cost of little end-to-end delay´s increase, we obtain a peak signal-to-noise ratio improvement up to about 10dB compared to the hybrid ARQ proposed in I A. Majumdar et al. (2002).