Starvation effect study in IEEE 802.11 mesh networks

Initially, IEEE 802.11 standard was not designed for multihop networks, but its market success gave it a powerful incentive, and nowadays IEEE 802.11 Working Group is preparing various amendments and looking for new application scenarios to ensure future success in the market. In this paper, we analyze the performance of an IEEE 802.11s mesh network and show that the effect of starvation caused by hidden terminals interference makes the distribution of channel capacity between links very much disproportional and unpredictable. Some links may be suppressed completely by other links and their throughput is close to zero. The effect of starvation was discovered by simulations in many papers. We investigate the roots of this phenomenon in a mesh network with an analytical model. Also, this paper reports the results of an outdoor testbed which was deployed to find out the scale of the starvation problem in a real network with Voice-over-IP, Video-over-IP and FTP traffic. While the results for VoIP may be considered as satisfactory, FTP traffic suffers dramatically from interference. So, at the end of the paper, we outline possible solutions to address starvation problem in mesh networks.