Performance analysis of random access mechanism in WiMAX

In this paper, we study the bandwidth request algorithm of the IEEE 802.16 standard for metropolitan broadband wireless access systems. The standard specifies the use of a random access scheme based on the slotted binary exponential backoff (BEB) algorithm during the bandwidth request phase. We analyze the distributed choice of the retransmission probabilities used by the BEB protocol. A Markov chain analysis is used to obtain the optimal retransmission probabilities, and the optimal value of initial window size Wopt. We derive the expressions allowing us to evaluate the mean delay and collision probability. We then follow a team problem approach in order to fine tune the design parameters of our algorithm. Throughout an extensive numerical analysis, our results show that the optimal retransmission probability decreases drastically as the arrival probability increases. Finally we provide the optimal parameterization of the Binary Exponential Backoff.