A Remainder-Based Contention-Avoidance Scheme for Saturated Wireless CSMA Networks

The traditional truncated-binary-exponential-backoff contention-resolution scheme can address the collision problem of carrier-sense multiple-access networks when the number of users is limited. However, its performance significantly worsens when many users join the contention or when the network is saturated. To address this issue, we propose a demand-assigned multiaccess (DAMA) time-division multiple-access (TDMA) system with a remainder-based contention-avoidance scheme. In our scheme, the wireless users are divided into several groups according to the available transmission opportunities in each time frame, and each user sends its bandwidth request during the time window for its group. According to the average collision probability and the utilization of the transmission opportunities in the last two rounds of contention resolution, the size of available transmission opportunities and the number of wireless users who issue bandwidth requests are adaptively controlled by the base station and the wireless users, respectively. Our analysis and simulation show that the proposed contention-avoidance scheme can significantly improve the performance of the entire network.