What is Medium Access Control

Recently there have been considerable interests focusing on the performance evaluation of IEEE 802.11e Medium Access Control (MAC) protocols, which were proposed for supporting differentiated quality of services in wireless local area networks (WLANs). Heterogeneous traffic generated by wireless multimedia applications and hidden stations arisen from the wireless transmission power constraints have significant impact on the performance of MAC protocols. This study performs extensive simulation experiments and conducts comprehensive performance evaluation of the IEEE 802.11e Enhanced Distributed Channel Access (EDCA) protocol in WLANs in the presence of hidden stations and heterogeneous traffic. For this purpose, non-bursty Poisson, bursty ON/OFF, and fractal-like self-similar processes with high variability are used to model and generate heterogeneous network traffic. The performance results have shown that this protocol is able to achieve differentiated throughput, access delay, packets loss probability, and medium utilization. However, the hidden stations can degrade the throughput and medium utilization as well as increase greatly the medium access delay, packets loss probability, and collision ratio under heterogeneous traffic.