Design and performance evaluation of an optimal collision avoidance mechanism over congested and noisy channels for IEEE 802.11 DCF access method

Abstract

For the IEEE 802.11 protocol, the basic access method in its medium access control (MAC) layer protocol is the distributed coordination function (DCF). However, this strategy incurs a high collision probability and channel utilization is degraded in bursty arrival or congested scenarios. Besides, when a frame is collided on a wired network, the sender should slow down, but when one is lost on a wireless network, the sender should try harder. Extending the backoff time just makes matters worse because it brings bandwidth wastage. In this paper, we identify the relationship between backoff parameters and channel BER and put forth a pragmatic problem-solving solution. In addition to theoretical analysis, simulations are conducted to evaluate the performance scheme. As it turns out, our design indeed provides a remarkable improvement in a heavy load and error-prone WLANs environment. © Springer-Verlag Berlin Heidelberg 2005.