Energy-efficient geographic routing in asynchronous wireless sensor networks

In geographic routing, data packet is forwarded hop-by-hop, where the next-hop relay is selected locally. The node holding the packet selects the next-hop relay based on the locations of itself, its one-hop neighbors, and the destination. The appeal of geographic routing lies in the fact that it can reduce the cost of route discovery and the burden of maintaining large-scale routing tables. However, existing works on geographic routing tend to degrade the performance in asynchronous wireless sensor networks (AWSN), where nodes alternate between active and sleep states periodically but not synchronously to save energy. In this paper, we propose an energy-efficient geographic routing protocol (EEGR) for AWSN. In the proposed protocol, both the geographic progress and the waiting energy cost incurred by asynchronous schedule are taken into account jointly when selecting the next-hop relay, to minimize the expected total energy consumed by forwarding the packet from the current node to the final destination. Extensive simulation results have shown that EEGR consumes less energy than existing geographic routing protocols in AWSN.