A modified backoff algorithm for IEEE 802.11 DCF-based MAC protocol in a mobile ad hoc network

The medium access control (MAC) protocol in IEEE 802.11 wireless LAN employs distributed coordination function (DCF) with binary exponential backoff (BEB) algorithm for contention resolution. With BEB, waiting time of a node gets doubled after every unsuccessful transmission. This introduces fast-growing retransmission delays for the backlog traffic. In a mobile ad hoc network (MANET), it would be worthwhile to slow down the growth-rate of waiting time. This is expected because the nodes communicating in a MANET might move out of collision range while waiting for retransmission. In this paper, we explore a modification to BEB algorithm and evaluate its performance through extensive simulations. Simulation results indicate that the proposed modification to BEB enhances packet delivery rate and reduces average end-to-end packet delay.