QoS MANAGEMENT FOR WIRELESS LANs

Abstract

In 802.11 wireless networks strict QoS requirement is not possible as the protocols DCF and EDCA used are contention-based medium access control protocols. In this work, three algorithms are proposed to improve the QoS. The first one is a rate adaptive call admission control scheme for IEEE 802.11 wireless LANs that gives preference to handoff calls. This algorithm focuses on real time multimedia applications with variable bandwidth requirements. The quality of service parameters used are new call blocking probability and handoff call blocking probability. The second algorithm is to improve Enhanced Distributed Channel Access (EDCA) mechanism of IEEE 802.11 e. In this algorithm, the parameters CW, PT', C W,,, ,, arc adjusted based on the collision probability so as to decrease the frame response times and improve the channel utilization. The third algorithm implements a dynamic scheduler for HCF Controlled Channel Access (HCCA) mechanism which estimates the transmission opportunity for variable bit rate applications with a bounded delay constraint.