Delay Constrained Admission Control and Scheduling Policy for IEEE 802.11e HCCA Method

Abstract

In order to obtain better Quality-of-Service (QoS) requirements for multimedia traffic, the 802.11TGe has proposed HCF Controlled Channel Access (HCCA) method for the Controlled Access Period (CAP) in the HCF (Hybrid Coordination Function) to enhance the original IEEE 802.11 Medium Access Control (MAC) protocol, and it is expected to provide integrated traffic service to realize mobile multimedia communications. However, the reference design of admission control and scheduling policy in HCCA still can not provide stringent delay requirements to fulfill a hard QoS guarantee, a necessary feature for most multimedia applications. In this chapter, the authors propose a pragmatic admission control scheme with a novel polling based packet scheduling policy for multimedia transmission, such as Constant Bit Rate (CBR) and Variable Bit Rate (VBR) traffic, for IEEE 802.11e HCCA method. Our design is simple, it is compatible with the standard, it can guarantee delay constraint, and it utilizes bandwidth efficiently. A simple and accurate analytical model is carried out to study the average queueing delay estimation of the proposed scheme. In addition to theoretical analysis, simulations are conducted in NS2 network simulator to verify our analysis and to validate the promising performance of the proposed scheme.