Saturation Throughput Analysis of the 802.11e Enhanced Distributed Channel Access Function

The IEEE 802.11e standard has recently been ratified. This standard provides quality-of-service (QoS) guarantees in the medium access control (MAC) layer of 802.11 wireless local area networks (WLANs). In other words, the 802.11e standard updates the MAC layer of the former 802.11 standard for QoS. In particular, the enhanced distributed channel access (EDCA) function of 802.11e is an enhancement of the distributed coordination function (DCF) of 802.11. In this paper, we present an analytical model for EDCA in saturation mode. Our model incorporates an accurate contention window (CW) and arbitration interframe space (AIFS) differentiation. In addition, it provides virtual collision treatment for an access category (AC). Validating the theoretical results via simulations, we show that i) the proposed model accurately captures EDCA saturation throughput, and ii) this model is substantially more accurate than the models previously proposed in the literature.