Feasibility and optimization of delay guarantees for non-homogeneous flows in IEEE 802.11 WLANs

Due to the rapid growth of real-time applications and the ubiquity of IEEE 802.11 MAC as a layer-2 protocol for wireless local area networks (WLANs), it is of increasing interest to support quality of service (QoS) in such WLANs. In this paper, we develop a simple but accurate enough analytical model for predicting queueing delay in non-homogeneous random access based WLANs. This leads to tractable solutions for meeting queueing delay specifications of a number of flows. Using this model, we address the feasibility problem of whether the mean delays required by a set of inelastic flows can be guaranteed in WLANs. Based on the model and feasibility analysis, we further develop an optimization technique to minimize the delays for inelastic flows. We present extensive simulation results to demonstrate the accuracy of our model and the performance of the algorithms.