Performance and Equilibrium Analysis of Heterogeneous IEEE 802.11 Based WLANs

This paper presents a general model to study the medium access control (MAC) layer performance and equilibrium of WLANs consisting of nodes with different MAC parameters (e.g., backoff window size). Our model can be used in general 802.11-based WLANs since it captures the important factors such as non-uniform backoff behavior, channel errors and unsaturated traffic. We first formalize the performance of 802.11 based MAC protocols with simultaneous fixed point equations. We then derive the average per-flow service time of each flow, and apply it to calculate throughput. More importantly, based on our model, we use interval analysis to formally study the existence and uniqueness of the network’s equilibrium, and find the sufficient condition for the uniqueness of equilibrium. We validate our model through simulations and the simulation results show that the model is quite accurate.