Double-covered broadcast (DCB): a simple reliable broadcast algorithm in MANETs

Mobile ad hoc networks (MANETs) suffer from high transmission error rate because of the nature of radio communications. The broadcast operation, as a fundamental service in MANETs, is prone to the broadcast storm problem if forward nodes are not carefully designated. The objective of reducing the broadcast redundancy while still providing high delivery ratio for each broadcast packet is a major challenge in a dynamic environment. We propose a simple, reliable broadcast algorithm, called double-covered broadcast (DCB), that takes advantage of broadcast redundancy to improve the delivery ratio in the environment that has rather high transmission error rate. Among 1-hop neighbors of the sender, only selected forward nodes retransmit the broadcast message. Forward nodes are selected in such a way that (1) the sender's 2-hop neighbors are covered and (2) the sender's 1-hop neighbors are either a forward node, or a nonforward node but covered by at least two forwarding neighbors. The retransmissions of the forward nodes are received by the sender as confirmation of their receiving the packet. The nonforward 1-hop neighbors of the sender do not acknowledge the reception of the broadcast. If the sender does not detect all its forward nodes' retransmissions, it will resend the packet until the maximum times of retry is reached. Simulation results show that the algorithm provides good performance for a broadcast operation under high transmission error rate environment.