Power-aware recovery for geographic routing

Maintaining low power consumption is critical in wireless ad hoc and sensor networks. With packet transmissions and retransmissions consuming much of the energy resources in wireless networks, it becomes important to minimize the number of transmissions associated with the end-to-end delivery of packets. Power-aware routing algorithms must balance the advantages and disadvantages of selecting to forward packets over shorter high-quality links against selecting longer and less reliable links. This paper proposes a new power-aware geographic routing technique that combines geographic greedy routing with probabilistic random walks to recover from local minima (i.e., cases when the forwarding node is not aware of any neighboring node providing "greedy" progress towards the destination). Building upon previous power-aware protocols without recovery mechanisms, our protocol uses simple distance metrics that combine information about the individual reception rates between node pairs and the relative forward progress candidate nodes provide towards the target destination. The combined metrics are used to make greedy choices (when at least one node provides progress) and probabilistic choices (when the packet recovers from a local minimum). Using simulations we show that power-aware routing significantly reduces the energy consumption in the network, and our probabilistic recovery mechanism can significantly increase the delivery rates with only a small decrease in energy efficiency.