ABSTRACT

A mobile ad hoc network enables wireless communications between participating mobile nodes without the assistance of any base station. Two nodes that are out of one another’s transmission range need the support of intermediate nodes which relay messages to set up a communication between each other. Network wide broadcasting is a fundamental operation in ad hoc networks. In broadcasting, a source node sends a message to all the other nodes in the network. The advantage is that one packet can be received by all neighbors. The disadvantage is that it interferes with the sending and receiving of other transmissions, creating exposed terminal problem, that is, an outgoing transmission collides with an incoming transmission, and hidden terminal problem, that is, two incoming transmissions collide with each other. The broadcast operation, as a fundamental service in mobile ad hoc networks , is prone to the broadcast storm problem if forwarding nodes are not carefully designated. The objective of reducing broadcast redundancy while still providing high delivery ratio is a major challenge in MANETs. The forward node selection has been studied extensively in undirected graphs in which each node has the same transmission range. In practice, the transmission ranges of all nodes are not necessarily equal. Objective of this paper is to provide a localized forward node list selection algorithm which operates with 2-hop neighborhood information in directed graphs in which each node has different transmission range. Among the nodes within the transmission range of the sender, only set of nodes are selected to retransmit the broadcast message. Simulation results show that the proposed broadcast algorithm provides good broadcast delivery ratio with low overhead and minimum latency.