A Mechanism to Improve the Performance of IEEE 802.11 MAC Protocol

Ad hoc networks are gaining popularity due to their less cost and ease deployment. Efficiency of these networks depend on the performance and reliability of the medium access control (MAC) protocol applied in such networks. Since the channel is shared by nodes, an efficient MAC should allow the nodes to access channel without degrading the performance. The performance of IEEE 802.11 gets degraded due to the presence of hidden and exposed terminal. IEEE 802.11 DCF was designed to overcome these problem using a virtual carrier sensing mechanism. Though IEEE 802.11 DCF is able to overcome the hidden and exposed terminal problem, the throughput and channel utilization is lower due to the inability of the hidden and exposed node to either transmit or receive. In this paper we proposed a mechanism that permits the hidden node to transmit and the exposed node to receive. The proposed mechanism also overcome the RTS induced and CTS-induced problem. We performed extensive simulation using NS-2 simulator. It is observed that the proposed scheme outperforms 802.11 DCF in-terms of throughput and packet delivery ratio with marginally increased in control overhead