Analysis of Quality of Service of Wireless LAN for IEEE 802.11e
Nowadays Wireless LAN is playing a more and more important role in network systems. After 1999, in which the IEEE organization published its Wireless Local Network standard 802.11[1], many people saw the advantages of the standard but also the lack of support for multimedia streaming. A lot of research work has been done on the proposed IEEE 802.11e standard draft during the past 4 years. It is supposed to be able to fully support Quality of Service. The final version will be published early in 2004. In my thesis, I propose two possible methods to improve the performance of service differentiation in the MAC layer. The first one is calledPCWA (Practical Contention Window Adjustment). It is a method with which the station finds a best size of its contention window when running the EDCF (Enhanced Distributed Coordination Function) access method. It helps to improve the total system throughput, the jitter and the delay of traffics with different priorities. The second method is called AIPM (Adaptive Initiative Polling Machine). It uses the polling mechanism for differential service, intelligently arranging the polling time to reduce the delay as much as possible, achieving large improvement in performance. This method significantly increases the total system throughput, while the delay and jitter of the traffics are very much small in comparison to EDCF.