The article investigates fairness in terms of throughput and packet delays among users with diverse channel conditions due to the mobility and fading effects in IEEE 802.11 WLAN (wireless local area networks) environments. From our analytical results, it is shown that 802.11 CSMA/CA can present fairness among hosts with identical link qualities regardless of equal or different data rates applied. Our analytical results further demonstrate that the presence of diverse channel conditions can pose significant unfairness on both throughput and packet delays even with a link adaptation mechanism since the MCSs (modulation and coding schemes) available are limited. The simulation results validate the accuracy of our analytical model.

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Fairness analysis of throughput and delay in WLAN environments with channel diversities

Most existing collision resolution schemes ore based on recent collision activities, which can not reveal the true stochastic nature of the collision activity process. In addition, they focus primarily on the system throughput without considering fairness issue. In this paper, we propose a novel collision resolution scheme that can incorporate the time-varying mean and variance of the stochastic collision process. It can also incorporate other fairness enhancement measures to achieve both good throughput and fairness performance. The scheme is adaptive in tracking non-stationary process and is also recursive which is very simple in implementation and energy efficient. Simulation results demonstrate that such scheme can improve the throughput and fairness significantly for IEEE 802.11 ad hoc networks.

Konrad Eriksson

Papers

A NEW DISTRIBUTED CONTENTION CONTROL PROTOCOL FOR THE IEEE 802.11 MAC LAYER - Project of ATcrc Application Programms