Maximizing Aggregate Throughput in 802.11 Mesh Networks with Physical Carrier Sensing and Two-Radio Multi-Channel Clustering

Abstract

Spatial reuse in a mesh network allows multiple communications to proceed simultaneously, hence proportionally improving the overall network throughput. To maximize spatial reuse, the MAC protocol must enable simultaneous cochannel transmitters to maintain a separation distance that is sufficient to avoid interference. Within that distance, a set of orthogonal channels is employed by different links. This paper demonstrates that physical carrier sensing enhanced with a tunable sensing threshold is effective at avoiding co-channel interference in 802.11 mesh (static + multi-hop) networks. Moreover, for multi-channel mesh networks, an architecture for channel clustering based on two-radio nodes is proposed. Distributed clustering is achieved using the Highest-Connectivity Cluster (HCC) algorithm.. All inter-cluster communications are performed on a common channel using the default radio, while-intra-cluster communications use the secondary radio with channel selection based on a new Minimum Interference Channel Selection (MIX) algorithm that minimizes the co-channel interference (CCI). Backward compatibility is guaranteed by allowing legacy single-channel devices to connect to the new two-radio devices through the common default radio. Simulation results for large-scale 802.11b and 802.11a networks demonstrate the significant improvement in one-hop aggregate throughput. Specifically, the new two-radio multi-channel mesh solution increases the aggregate throughput by more than twice w.r.t. the traditional single-radio single-channel mesh.