The Performance Analysis And Research Of IEEE 802.11e EDCA

With applications over IEEE 802.11 WLAN increasing, customers demand more and more new features and functions. One important feature is the support of multimedia applications with quality of service (QoS). However, the original IEEE 802.11 standard was designed for best effort data traffic. Recently, IEEE 802.11 work group proposed 802.11e standard to meet the delay and jitter requirements of multimedia services. The research target of this dissertation is to investigate the influence of EDCA parameters of IEEE 802.11e EDCA and propose an analytical model for varying traffic loads. Based on the results from the analysis, we propose a new call admission control (CAC) algorithm to provide and support the QoS of existing calls.In the dissertation, we first propose a new analytical model for IEEE 802.11e EDCA function based on existing 802.11 DCF model. It covers EDCA parameters of IEEE 802.11e and wireless channel errors. It also fits the simulation results well.Enhanced distributed coordination access (EDCA), being the fundamental medium access control mechanism in IEEE 802.11e, can only provide service differentiation but offers no QoS guarantees. While service differentiation does not perform well under high traffic load conditions, CAC becomes necessary in order to provide and support the QoS of existing calls. We provide an extensive survey of recent advances in admission control algorithms/protocols in IEEE 802.11e WLANs and propose a new CAC algorithm that provides QoS for existing flows. Simulated performance results demonstrate the effectiveness of the proposed CAC algorithm.