Efficient "Void" Handling in Contention-Based Geographic Routing for Wireless Sensor Networks

Due to its scalability and simplicity, geographic routing¹ has gained much research attention as a basic routing primitive in wireless sensor networks (WSN). However in geographic routing, due to ad hoc or random deployments and network dynamics of WSN, communication holes may exist in a network area, where no next hop candidate is closer to the destination than the node currently holding the packet. Recovery strategies are applied to help packets move out of the void areas provided a path does exist between source and destination nodes. Current void recovery schemes include increasing the transmission power, employing right/left handle rule or distance update etc. In this paper, we propose a contention-based geographic routing (CGR) protocol using a novel on-line "void" avoidance technique. We combine forwarding area determination, void handling, and load balancing in a single back-off function that is used as a cost metric to effectively locate the next hop node. Packets can be delivered to the destination along paths that are near optimal from depth first search (DFS) perspective. We term the new protocol as CGR-D, in which "D" represents DFS. Simulation results show that the new routing protocol outperforms existing algorithms in terms of total packets delivered, lifetime, and path length when voids exist in the network.