A grid-based sink location service for large-scale wireless sensor networks

Location-based routing (LBR) is one of the most widely used routing strategies in large-scale wireless sensor networks (WSN). With LBR, small, cheap and resource constrained nodes can perform the routing function without the need of complex computations and large amount of memory space. Further, the nodes don't need to incur in energy consuming periodic advertisements because routing tables, in the traditional sense, are not needed. One important assumption made on most LBR protocols is the availability of a location service or mechanism that the nodes can utilize to find other nodes positions. Although several mechanisms exist in the literature, no efficient mechanism is available for a source to find the location of the sink or sinks. In this paper, we introduce the Anchor Location Service (ALS) protocol, a grid-based location service strategy for source nodes to find the sinks' locations and support location-based routing in large-scale wireless sensor networks. We describe the grid set up and query processes and evaluate the delay and overhead of this mechanism by varying the number of sinks, considering networks of different sizes, and the case where the sink nodes move, not common in the literature. Using simulations, we demonstrate that ALS provides the required service in a scalable and efficient manner.