Supporting VoIP Traffic in IEEE 802.11 WLAN with Enhanced Medium Access Control (MAC) for Quality of Service

With fast deployment of wireless local area networks (WLANs), the ability of WLAN to support real time services with stringent quality of service (QoS) requirements has come into fore. In this paper, we evaluate the capability of the enhanced point coordination function (EPCF) and enhanced distributed coordination function (EDCF), which are part of the medium access control (MAC) enhancements for QoS in the IEEE 802.11e supplements, to support voice over IP (VoIP) applications. The performance of VoIP under EPCF and EDCF is shown through simulations, and the impact of background traffic on the VoIP performance is also evaluated. Our results show that under the EPCF mode the end to end delay of VoIP traffic may be effectively controlled with admission control, and is not sensitive to the best effort traffic offered in contention based operation mode.