The Novel Contention Window Control Scheme for IEEE 802.11 Mac Protocol

The IEEE 802.11 medium access control (MAC) protocol defines a contention-based distribution channel access mechanism that shares the wireless medium for mobile stations. In this paper, we present a novel back off mechanism, which divides contention window range to the different level based on the history of channel status. Instead of doubling and resetting the CW, we change the CW range by taking into account last three channel states. We test the new scheme against legacy IEEE 802.11 with NS-2 network simulator. The simulation results have shown 30.77% improvement in packet delivery ratio and 31.76% in delay and 30.81% in throughput compared to the IEEE 802.11 DCF.