Optimal Carrier Sensing Range in Coexisting Wireless Networks

Abstract

This paper derives a model that computes the optimal carrier sensing range adopted by transmitters of a Carrier Sense Multiple Access (CSMA) network when multiple wireless networks coexist in the same band. To investigate the optimal carrier sensing range, we define a utility function that considers the impact of the carrier sensing threshold in the medium access probability and the transport capacity of a CSMA transmitter. Consequently, the definition of the carrier sensing range is a tradeoff between the avoidance of low channel access probability due to low carrier sensing thresholds and the avoidance of a high number of concurrent transmissions (collisions) per unit area due to high carrier sensing thresholds. Considering the aggregate power sensed by a CSMA node, we derive a method to compute the optimal carrier sensing range. The proposed solution is adopted in two different scenarios, considering the cases when the coexisting networks are spatially overlapped or non-overlapped. Extensive simulation results indicate that the optimal carrier sensing range is accurately approximated for the two scenarios, and higher optimal carrier sensing ranges are obtained for the overlapped scenario. The proposed method is a useful tool to find the optimal carrier sensing range when the spatial distribution of the coexisting networks is known.