Leveraging spatial reuse in 802.11 mesh networks with enhanced physical carrier sensing

Abstract

Spatial reuse in a wireless network can allow multiple communications to proceed simultaneously, hence proportionally improve the overall network throughput. To maximize spatial reuse, the MAC protocol must enable simultaneous transmitters to maintain the minimal separation distance to avoid interference. This paper demonstrates that physical carrier sensing enhanced with tunable sensing threshold is effective at avoiding interference in 802.11 mesh networks without requiring the use of virtual carrier sensing through RTS/CTS. We present analytical model that demonstrates how to derive the optimal sensing threshold given reception power, data rate and network topology. Simulation results are shown for large-scale 802.11b networks to demonstrate that physical carrier sensing with the optimally tuned threshold improves network throughput by maximizing the potential of spatial reuse. In the case of a regular chain topology of 90 nodes, with tuned physical carrier sensing, the end-to-end throughput approaches 90% of the theoretical upper bound that assumes a perfect MAC protocol. Hence, without modifying the 802.11 MAC protocol, our enhanced physical carrier sensing mechanism effectively maximizes the potential of improving network throughput with spatial reuse.