Improving Geographical Routing for Wireless Networks with an Efficient Path Pruning Algorithm

Geographical routing is powerful for its ability to discover route to the destination without the help of global state. However, detours usually occur when the packet reaches a local minimum. In this case, the network topology has to be reduced to a planar graph and recovery schemes such as face routing are needed. However, face routing may create a large number of hops on a planar graph. When multiple packets are generated for the same destination, such a large number of hops tends to consume more energy. In this paper, a simple yet effective path pruning strategy is proposed to reduce the excessive number of hops caused by the detouring mode of geographical routing protocols. The path pruning algorithm finds routing shortcuts by exploiting the channel listening capability of wireless nodes, and is able to reduce a large number of hops with the help of little state information passively maintained by a subset of nodes on the route. The average hop count of the proposed algorithm is compared to those of existing geographical routing algorithms and the benchmark shortest path algorithm. Simulation results show that in average the path pruning algorithm can reduce as much as 80% of hops on the routes obtained by greedy perimeter stateless routing (GPSR) and greedy other adaptive face routing⁺ (GOAFR ⁺) in a critical network density range