Error protection of video over wireless local area networks through real-time retry limit adaptation

Robust streaming of video over 802.11 wireless LANs (WLANs) poses many challenges, including coping with packet losses caused by network buffer overflow or link erasures. In this paper, a novel error protection method for wireless video, utilizing a retry-limit adaptation algorithm at the link layer, is proposed. The design of this method is motivated by the observation that the retry limit settings of the MAC layer can be optimized to minimize the overall packet losses that are caused by either link erasure or buffer overflow. To develop this method, we conducted theoretical analyses; on the relation between MAC retry-limit settings and packet error rates, and developed a real-time retry-limit adaptation algorithm to trace the optimal retry limit for the single-queue case under varying wireless channel conditions and traffic loads. Simulations show that the proposed cross-layer protection method can significantly reduce over-all packet losses and improve network throughput, resulting in better video quality.