Adaptive traffic for VoIP to improve the QoS

Voice over Internet Protocol is an important service with strict quality of requirements in Wireless Local Area Network (WLANs). The IEEE 802.11e Standard has been introduced recently for providing Quality of Service (QoS) capabilities in the emerging wireless local area networks. The IEEE802.11e is an approved amendment to the IEEE802.11 standard that defines a set of Quality of Service enhancements for Wireless LAN applications through modifications to the medium access control layer. This 802.11e introduces a contention window based that is Enhanced Distribution Channel Access (EDCA) technique that provides a prioritized traffic to guarantee minimum bandwidth needed for time critical applications. However this EDCA technique resets statistically the contention window of the mobile station after each successful transmission. This static behavior does not adapt to the network state hence reduces the network usage and results in bad performance and poor link utilization whenever the demand for link utilization increases. For that purpose a new adaptive differentiation technique has been proposed for IEEE 802.11e wireless local area networks that take into account the network state before resetting the contention window.