A time-based adaptive retry strategy for video streaming in 802.11 WLANs

Abstract

Video streaming over time-varying, error-prone wireless LANs (WLANs) poses many challenges. One problem is that WLANs are designed without awareness of the characteristics of application data, which causes performance degradation in a noisy or congested environment. In this paper, we propose a time-based adaptive retry (TAR) mechanism for MPEG-like video streaming over 802.11 wireless networks. TAR dynamically determines whether to send or discard a packet based on its retransmission deadline instead of adopting a static retry limit uniformly over all the packets. Our approach can adapt the retry limit for each individual packet, thus providing indirect unequal error protection over different types of video frames. Analytical and simulation results show that TAR significantly improves video quality and saves channel bandwidth. We also describe a preliminary software-based implementation of TAR and use it to demonstrate the practicality of the proposed approach. Copyright © 2007 John Wiley & Sons, Ltd.