A Liberal Carrier Sensing for Increased Spatial Reuse in Multi-Hop Wireless Ad Hoc Networks
Mayur M. Vegad, Swades K. De, Brejesh Lall · 2010
Recent experimental results have shown that the minimum signal-to-interference ratio required at a receiver (CPth) depends on the order of arrival of the overlapping frames. For a given sender-receiver distance, this differential capture capability of a receiver leads to two distinct interference ranges (ri) around the receiver, and its value is much smaller when the sender's frame arrives earlier. This feature also suggests a possibility of increased spatial reuse by allowing the (secondary) nodes outside the primary receiver's rito communicate concurrently once the primary receiver starts its DATA reception. In this paper, we propose a liberal carrier sensing (LCS) scheme wherein some already available information at an otherwise 'exposed' receiver are exploited to help decide when it is safe to respond to a secondary transmission request. The proposed modification in the carrier sensing approach results in a significantly improved spatial reuse, thereby increasing overall system throughput. Our simulation studies show that, compared to the conventional carrier sensing scheme with differential capture capable receivers, the end-to-end TCP throughput with LCS can be improved by more than 20% in regular topologies and up to about 9% in random topologies.