Performance Optimization Of IEEE 802.11e MAC Protocol

In recent years, IEEE802.11 Wireless LAN has emerged as a prevailing technology for the (indoor) broadband wireless access.IEEE802.11 can be considered a wireless version of Ethernet by virtue of supporting a best-effort service, but not guaranteeing any service level to users/applications. The IEEE802.11 Working Group is currently defining a new supplement to the existing legacy 802.11 Medium Access Control (MAC) sub-layer in order to support Quality of Service (QoS)[1].The IEEE802.11e is an extension of the IEEE802.11 to provide Quality of Service (QoS) for applications requiring real time services. However, when used with the multi-rate scheme, they suffer unfairness problem. On the other hand, the IEEE 802.11e could not efficiently guarantee a negotiated Quality of Service (QoS) level to users and support the multimedia traffic. In this paper, we analysis a novel model based on the Markov chain, which takes into account almost all the important MAC parameters, and use it to analysis the fairness-based TXOP turning mechanism. At the same time, we proposed a mechanism to dynamically turn the priority or the transmission rate of the station, solves the unfairness problem in the IEEE802.11e networks employing the multi-rate scheme, and enhances the throughput of the system.