Indexed on: 08 Feb '15Published on: 08 Feb '15Published in: Wireless Networks
In this paper, we derive an analytical model to evaluate the effect of jointly tuning the carrier sense threshold and employing multiple data rates on the network capacity in wireless ad-hoc networks. In order to capture the effect of the carrier sense threshold, the proposed model characterizes the channel states within the carrier sense range of an individual transmitter. Multi-rate capability for transmission is incorporated in identifying the channel states observed by a node. Towards maximizing the per-node throughput derived from the analytical model, a control reference and its optimal operating range is then identified. Based on the findings we propose a reference based channel access scheme, working in run-time and distributed fashion. Under the proposed scheme, each node measures the number of idle slots between two consecutive busy slots on-line and tunes the contention window size so as to ensure the measured control reference located within its optimal operation range. At the same time each node performs the selection of the data rate and the corresponding carrier sense threshold dealing with the current channel and network dynamics. Simulation results show that the proposed scheme achieves a performance improvement of up to 81 % in terms of per-node throughput over conventional 802.11 DCF algorithm.