On Improving WLAN Medium Access Control via Uniform Transmission Cycle and Performance Analysis

Abstract

In this paper, we propose a modified backoff mechanism that can be used in conjunction with the existing backoff algorithms for medium access sharing among wireless stations via the CSMA protocol. With a proper design, the resulting scheme can achieve better short-term throughput fairness performance without degradation in the average throughput performance. The main idea of the proposed scheme is to virtually create a transmission cycle for each wireless station. After getting a turn to access the medium, each wireless station is not allowed to start the backoff procedure for its next transmission until it has waited for some additional number of backoff slots. Moreover, the average throughput performance of the proposed scheme is analytically evaluated in this work via the Markov chain approach. The simulation results show that the performance analysis model derived here for the proposed scheme is valid and accurate. In addition, the proposed scheme noticeably improves the short-term throughput fairness performance of the conventional backoff scheme.