Identifying High Throughput Paths in 802.11 Mesh Networks: a Model-based Approach

We address the problem of identifying high throughput paths in 802.11 wireless mesh networks. We introduce an analytical model that accurately captures the 802.11 MAC protocol operation and predicts both throughput and delay of multi-hop flows under changing traffic load or routing decisions. The main idea is to characterize each link by the packet loss probability and by the fraction of busy time sensed by the link transmitter, and to capture both intra-flow and inter-flow interference. Our model reveals that the busy time fraction experienced by a node, a locally measurable quantity, is essential in finding maximum throughput paths. Furthermore, metrics that do not take this quantity into account can yield low throughput by routing over congested paths or by filtering-out non-congested paths. Based on our analytical model, we propose a novel routing metric that can be used to discover high throughput path in a congested network. Using city-wide mesh network topologies we demonstrate that our model-based metric can achieve significant performance gains with respect to existing metrics.