A Measurement-Aided Model-Based Admission Control Scheme for IEEE 802.11e EDCA Wireless LANs

The IEEE 802.11e standard was introduced to overcome the lack of QoS support for the legacy IEEE 802.11 WLANs. It enhances the Media Access Control (MAC) layer operations to incorporate service differentiation. However, there is a need to prevent overloading of wireless channels since the QoS experienced by traffic flows is degraded with heavily loaded channels. An admission control scheme for IEEE 802.11e WLANs would be the best solution to limit the amount of multimedia traffic so that channel overloading can be prevented. This paper proposes a measurement-aided model-based admission control scheme for IEEE 802.11e Enhanced Distributed Channel Access (EDCA) Wireless Local Area Networks (WLANs) to provide reasonable bandwidth guarantees for traffic flows. The admission control scheme makes use of bandwidth estimations that allows the bandwidth requirements of all the flows that are admitted into the network to be protected. The bandwidth estimations are obtained using a developed analytical model of EDCA WLAN channels. The admission control scheme also aims to accept the maximum amount of flows that can be accommodated by the network’s resources. Through simulations, the performance of the proposed admission control scheme is then evaluated using NS-2. The results validate that the bandwidth needs of all admitted traffic are always satisfied when the admission control scheme is used. It also shows that the admission control scheme allows the maximum amount of flows to be admitted into the network, according the availability of the network’s capacity.