Performance Evaluation of IEEE 802.11 MAC DCF Using Various Schemes Towards: Throughput, Delay and Reliability

Abstract: Wireless local area networks (WLANs) have become increasingly popular in the computer communications industry in recent years. Performance improvement of IEEE802.11 is a challenging & very popular problem between the researchers. CW (Contention Window) is an important factor, which plays an important role to improve or reduce the performance of IEEE 802.11. We modify the calculating method of CW (Contention Window) size after a Successful & unsuccessful transmission and study the effect of CW size on performance. The proposed modification significantly reduces the probability of collision and provides better quality of service. The complexity of implementing such a modification is low and the related parameter is easily determined. Simulation results show that the proposed modification outperforms DCF in terms of throughput, the probability of collision and average delay.

Keywords: 802.11;DCF(Distributed Coordination Function); MAC(Medium Access Control);BEB(Binary Exponential Backoff);CSMA/CA(Carrier Sense Multiple Access With Collision Avoidance) ;QoS (Quality of Service).