An Analysis of the Coexistence of IEEE 802.11 DCF and IEEE 802.11e EDCA

IEEE 802.11e standard has been published in 2005. In the next few years, we may expect a proliferation of 802.11e capable stations. In the mean time, the legacy 802.11 stations will exist Therefore, it is of practical significance to study the network performance when 802.11 stations and 802.11e stations coexist. In this paper, a novel Markov chain based analytical model is proposed to investigate the coexistence of DCF and EDCA, which are the fundamental access mechanisms for 802.11 and 802.11e respectively. The performance impact of the differences between DCF and EDCA is analyzed, including the contention window (CW) size, the interframe space (IFS), the backoff counter decrement rule, and the transmission timing when the backoff counter reaches zero. Based on the proposed model, the saturated throughput is analyzed. Simulation study is carried out to evaluate the accuracy of the proposed model.