Energy-efficient return-path routing in wireless sensor networks

As sensor nodes are powered by battery of limited lifespan, energy consumption has always been an important issue in sensor networks. New generation of sensor network technology bring about the possibility of constructing a spatial index over a sensor network such that sensor queries are forwarded only to the relevant nodes. Existing spatial indices share the common feature of using the same node path for propagating queries and routing back results. Hence, intermediate nodes along the path incur heavier workload than non-intermediate nodes and drain their battery more quickly. In this paper, we propose a multi-parent method to share the workload of intermediate nodes so that sensor results have alternative return paths to the sink node. As a result, the lifespan of the entire sensor network can be prolonged. We study the performance and effects of this method under three different kinds of spatial index structures. Our experiments show that the proposed approach is able to prolong the sensor network lifespan especially when the sensor network is dense. The experiments also yield various interesting information on the performance of the proposed approach under various conditions of the sensor network.