Improving Quality of Service of Real Time Traffic in Wireless Local Area Network

The IEEE 802.11e standard has been introduced recently for providing Quality of Service (QoS) capabilities in the emerging wireless local area networks. Because the performance of EDCA of IEEE802.l le becomes critical when the number of mobile stations increases. In this work an Adaptive Contention Window mechanism is proposed, which dynamically selects the optimal contention window according to the estimate of the number of contending stations for each haffic category. This is done by using two control parameters set differently for each traffic category in successful and collision case respectively. It is compared with other adaptive technique and the results show that the proposed adaptive technique enhances the channel utilization by increasing throughput, decreasing delay and decreasing collision probability in all number of stations.