QoS-PCF: An Enhanced Mechanism of PCF for QoS Support in IEEE 802.11 Wireless LANs

I. Smaoui, M. Ben Jemaa (Tunisia), and A. Koubaa (Saudi Arabia)



As wireless networks are rapidly deployed, different traf fic classes will exhibit a large variety of characteristics and QoS requirements, such as bandwidth rate, maximum tol erable bit error rate and delay. the PCF standard has been shown to have some lacks for guaranteeing QoS for flows with specific QoS requirements. The contribution of this paper is the proposal of QoS-PCF, an extension of the Point Coordination Function (PCF) mode of the IEEE 802.11 MAC protocol. This new scheme can be used to enhance the QoS support for multimedia traffic in IEEE 802.11 WLAN. The main idea of QoS-PCf is to use broadcast in polling wireless stations at the beginning of a contention free period and in data acknowledgements at the end of the same period. Its performance has been evaluated and compared to PCF and DCF using Network Simulator NS-2. We show that QoS-PCF outperforms the standard PCF in terms of delay and throughput guarantees for real time traffic and fairness. IEEE 802.11, WLAN, QoS, PCF, DCF, QoS-PCF, perfor -mance evaluation.

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