Short-Term Fairness of 802.11 Networks with Several Hosts

Previously, we have analyzed the short-term fairness of the 802.11 DCF (Distributed Coordination Function) access method in the case of a network with two hosts. In this paper we extend the analysis to an increased number of hosts. We use two fairness indices. The first one is the number of inter-transmissions that other hosts may perform between two transmissions of a given host. The second index is based on the sliding window method that considers the patterns of transmissions and computes the average Jain fairness index in a window of an increasing size. Computed over traces gathered during measurement sessions the indices show that the fairness of 802.11 is pretty good even on the short term time scale. We also evaluate the impact of the short-term fairness on performance by providing the measurements of the delay.