Revisiting the Markov Chain Model of IEEE 802.11E EDCA and Introducing the Virtual Collision Phenomenon

IEEE 802.11e specifies the Enhanced Distributed Channel Access (EDCA) for distributed access with traffic differentiation to a Wireless Local Area Network (WLAN). Traffic differentiation led to introducing several traffic queues within each station, thus introducing virtual collision. In this paper, we present a pattern based Markov chain model of EDCA including the virtual collision phenomenon not found in previous work. We also correct the misconceptions found in existing Markov chain models of EDCA (Kong et al., 2004). We thus obtain a more realistic model of IEEE 802.11e EDCA which will allow a more precise performance analysis that may be used for admission control.