Cross-layer route optimization using MAC overhearing for reactive routing protocols in MANETs

Existing route optimization algorithms rely on dedicated control packets to explore topology changes and to propagate modified routing information, which accelerates the energy and bandwidth depletion. In this paper we introduce a new cross-layer route optimization algorithm that can completely eliminate the dedicated control packets by allowing each node to observe its surrounding topology without transmitting any control packet. Each node can discover a downstream node moving into its communication range by overhearing data packets from its neighbors. As soon as a node detects a downstream node, it can update its routing information with respect to the downstream node. However, the immediate neighbors of a destination may not overhear data packets from the destination since it does not forward any data. To address this problem a destination node uses existing MAC control packets such as CTS and ACK to inform neighbors of its identity. We evaluate the optimality and the networking performance of our algorithm by using NS-2 simulator. Simulation results demonstrate that our algorithm can improve the channel utilization and the energy efficiency by eliminating dedicated control packets while it also improves path optimality compared to the existing algorithms.