WLAN QoS Issues and IEEE 802.11e QoS Enhancement

Abstract

Wireless communication systems either ad hoc or infrastructure mode the key challenges that must be overcome to realize the practical benefits of Quality of Service (QoS). Generally the QoS is the ability for network element to provide some level of assurance for consistent network data delivery. The ability of Wireless Local Area Network (WLAN) to support real-time services is possible with QoS. IEEE802.11 is a standardized protocol for Wireless LAN (WLAN). To improve the QoS, the original IEEE Medium Access Control (MAC) protocol is enhanced to IEEE 802.11e standard by introducing new coordination functions, which has both contention based and contention free medium access methods. In this paper we evaluated the QoS support of IEEE802.11e standard, by comparing the fairness index and total data carrying capacity of the contention based medium access method, the EDCA and a extension to it a contention free HCF control channel access (HCCA), both are considered to guarantee QoS in WLAN operating in the infrastructure mode.