Performance Analysis and Optimization of IEEE 802.11 DCF with Constant Contention Window

In this paper, a novel MAC protocol, DCF with constant contention window (DCF/CCW), is proposed for IEEE 802.11 WLANs. Firstly a mathematical model is presented to analyse the throughput and access delay of DCF/CCW. The analysis shows that the performance of DCF/CCW differs much with different network scales. And a further analysis shows it is easily to obtain the optimal CCW for a given network scale in order to maximize the system throughput. The proposed optimization mechanism, optimal-DCF/CCW, is just based on this knowledge to select optimal CCWs for different network scales. Simulation results show that compare with IEEE 802.11 DCF, optimal-DCF/CCW makes a significant improvement of throughput and access delay.