Enhancing the IEEE 802.11e in QoS support: analysis and mechanisms

Despite its support of prioritized services, the IEEE 802.11e Enhanced Distributed Channel Access (EDCA) cannot guarantee strict QoS required by real-time services such as voice and video without proper network control mechanisms. To overcome this deficiency, we first build an analytical model to derive upper bounds for both delay means and variations for services of different priorities in the non-saturated 802.11e WLAN, showing that the QoS re-quirements of real-time services can be satisfied if the input traffic is properly regulated. Based on the analysis, we then propose a call admission control scheme and a rate control scheme to ensure that QoS requirements of real-time ser-vices are statistically guaranteed and that best effort ser-vices can efficiently use the residual bandwidth.