Modelling and analysing medium access delay for differentiated services in IEEE 802.11s wireless mesh networks

Wireless mesh networks (WMNs) has been actively explored for a few years, and the IEEE 802.11 Task Group “s” has recently approved the active 802.11s standard for Wireless local area network (WLAN) mesh networking. To provide differentiated channel access and quality of service (QoS) guarantees for multimedia flows, IEEE 802.11s standard employs enhanced distributed channel access (EDCA) as the basic medium access control (MAC) protocol. In this study, the authors focus on modelling and analysing the medium access delay differentiation of EDCA under saturation condition in multi-hop WMNs. The authors develop a three-dimensional Markov chain model to evaluate the medium access delay differentiation of EDCA. In this model, the authors fully consider the performance impact of Request to Send (RTS) frame collisions and data frame collisions and then put forward the pseudo states to distinguish the different back-off procedures induced by these collisions. Using this analytical model, the authors derive the average medium access delay for the flows with different priorities. Comparisons with the simulation results show that the analytical model is extremely accurate.