A Comprehensive Analytical Model for IEEE 802.11e QoS Differentiation Schemes under Unsaturated Traffic Loads

Arbitrary inter-frame space (AIFS), contention window (CW) and transmission opportunity (TXOP) are three important quality-of-service (QoS) differentiation schemes specified in the IEEE 802.11e enhanced distributed channel access (EDCA) protocol for wireless local area networks (WLANs). Analytical models of EDCA in the current literature have been mainly developed for the AIFS, CW, and TXOP schemes, separately. This study proposes a comprehensive analytical model to accommodate the combination of these three QoS schemes in WLANs under unsaturated traffic loads. We derive the performance metrics in terms of throughput, end-to- end delay, and frame loss probability. Extensive simulation experiments are conducted to validate the accuracy of the model.