Performance of multi-radio wireless mesh networks: An experimental approach

We present a performance study of a wireless mesh network based on off-the-shelf 802.11 technology. Unlike earlier work, we explore the practical constraints of the use of a "vanilla", unmodified 802.11 MAC layer. We also consider the use of multiple radios, in the 5GHz band, to reduce interference. We establish the origin of degradation and limits in performance of practical deployments and study means to circumvent them. We focus our analysis on simple means, deployed in the network without attempting to modify the Internet Protocol stack on clients and focusing on ubiquitous layer 3 mechanisms, which limit bandwidth and only influence sharing. Using as a yardstick equity between TCP flows, which more than ever represent the dominant support for application traffic in the Internet, we show which improvements can be achieved over unmanaged usage and at what cost, and discuss implications for their use.