Energy-efficient geographic routing with virtual anchors based on projection distance

Geographic routing is an effective routing technique based on locally available position information. It uses greedy forwarding whenever possible and switches to detouring mode when a local minimum is reached. Detouring mode in geographic routing usually results in lengthy paths. To shorten the path and reduce the possibility of detouring, geographic routing using anchor nodes as intermediate relays has been proposed. In this paper, we propose to obtain the anchor list based on the projection distance of nodes in detouring mode with respect to the virtual line linking the source and destination. For existing anchor-based schemes, once an anchor list is obtained, the path from the source to the destination usually does not change unless the network topology changes, which may lead to the quick depletion of the energy for some nodes. To better distribute energy consumption among nodes in the network and thus prolong the network lifetime, we further propose to introduce a random shift to the location of anchors to obtain virtual anchors for each packet sent. Simulation results show that our projection distance-based algorithm outperforms existing anchor-based algorithms with shorter paths and fewer anchors in random network topology. We also demonstrate that the lifetime-improving strategy with virtual anchors is effective in increasing the number of packets delivered in the lifetime of sensor networks.