Efficient routing to mobile sinks in wireless sensor networks

In a typical wireless sensor network covering a large geographical area the range of the sensors' radio is in general quite short when compared to the network size. Thus, multihop communication is essential where nodes relay information packets between the source nodes and the sink(s). Because of the low-cost tiny devices the operation of the network is highly energy sensitive. The lifetime of the network largely depends on the energy of the sensor nodes neighboring the sink(s) that relay all messages on the last hop. Our solution to overcome this limitation is to use mobile sink(s) to move away from depleted areas. However, mobility raises several routing issues. In this paper we present a simple yet effective routing protocol, which uses restricted flooding to update the paths towards multiple mobile sinks in the network. The proposed solution tries to find a compromise between the optimal routes and the number of messages needed to update these routes. Routes are only updated where the degree of topology change requires it. We neither require sinks to subscribe for specific data in advance, nor need sink agents, and sinks are allowed to move on arbitrary paths.