Identification and mitigation of throughput unfairness in WLANs

Abstract

Co-channel interference exists in IEEE 802.11 based wireless local area networks (WLANs) due to the limited number of non-overlapping channels in the current standards. In this thesis, the impact of co-channel interference is investigated in carrier sense multiple access with collision avoidance (CSMA/CA) based WLANs through simulation. Severe throughput unfairness is found among the users in WLANs due to asymmetric co-channel interference among the users. To mitigate the throughput unfairness problem in WLANs, a centralized algorithm is developed to configure the minimum contention window of the nodes based on an analytical formulation. A heuristic is also developed to configure the minimum contention window of the nodes based on the results of the centralized algorithm and a simple distributed algorithm is proposed to mitigate the throughput unfairness problem. The performance of the proposed algorithms is evaluated by simulation and found to be very effective. It is found that the distributed provides better fairness than the centralized algorithm. However, the total network throughput under the distributed algorithm is little bit less than the centralized algorithm.