An Analytic Model for the Delay in IEEE 802.11 PCF MAC-Based Wireless Networks

In this paper, we present an analytic model for evaluating the queueing delays at nodes using the IEEE 802.11 point coordination function (PCF) MAC for real time, delay sensitive traffic. We develop a queueing model to obtain closed form expressions for the expected delay at each node which accounts for arbitrary (but fixed) packet sizes, polling rates, channel rates and the order in which the nodes are polled. The model is then further extended to account for the delays when the nodes use power management, and for cases when not all nodes are served in a frame. Our analytical results are verified through simulations. The model is also extended to evaluate the number of nodes that can be supported by a base station while satisfying an arbitrary delay requirement at all nodes and can be used as a mechanism for admission control by the base station