Abstract:

In order to improve the throughput of wireless local area networks （ WLAN）, this paper proposes a MAC （Medium Access Control） backoff algorithm named QIQD （ Quadratic Increase, Quadratic Decrease） based on quadratic curves. QIQD uses piecewise quadratic curves to respectively calculate the muhiplicator of the contending window after a frame collision and the divisor after a successful frame transmission, and overcomes the drawbacks caused by constant backoff factor, thus reducing the collision probability and improving the channel utilization. The backoff window threshold Wbasic of QIQD is then explored and extensive simulations are performed. It is confirmed that when Wbasic= 64, QIQD possesses the highest throughput and the fairest performances. It is also found from the simulations that QIQD effectively reduces the collision probability, improves the network throughput and enhances the fairness between any two stations.

Key words: wireless local area networks, medium access control, backoff algorithm, distributed coordination control