A MAC parameter optimization scheme for IEEE 802.11e-based multimedia home networks

Enhanced Distributed Channel Access (EDCA) is a channel access scheme adopted by the IEEE 802.11e draft standard for QoS-enabled wireless local area networks. It classifies traffic into separate Access Categories (ACs) and achieves service differentiation by allowing each AC to have its own values of channel access parameters, i.e. minimum and maximum Contention Window (CW) and InterFrame Space (IFS). Since the network performance is highly sensitive to these parameters, their values should be carefully determined. The IEEE 802.11e specification, however, includes only default recommended values and does not deal with run-time optimization. This paper proposes a scheme to dynamically adapt the EDCA parameters to traffic environment so that they both maximize the throughput of non real-time traffics and meet the delay and throughput constraints of real-time traffics. For this purpose, we develop a design time algorithm for efficient exploration of the EDCA parameter space. Using the algorithm, we derive a Pareto curve for delay-throughput trade-off in each anticipated traffic environment. The Pareto database can then be used to optimally adjust the parameter according to the traffic environment and administrative policies. Simulation results show that compared with the default parameter configuration, the proposed scheme is better for delay, throughput guarantee and can improve the throughput of non real-time traffics by 12% on average.