A decentralized location system for sensor networks using cooperative calibration and heuristics

In this paper we study the problem of determining the location of nodes in a wireless sensor network, describing a fully decentralized algorithm called HECOPS, where every node estimates its own position after interacting with other nodes. Only a limited number of nodes have exact knowledge of their position coordinates. Any node can, however, be selected as a reference. We establish a ranking system to determine the reliability of each estimated position. This leads to a novel approach for position calculation that uses fewer but more reliable landmarks, thus reducing data communication and limiting error propagation. We present heuristics that are used to reduce the effects of measurement errors, including a scheme to calibrate range measurements by comparing, whenever possible, the estimated distance with the actual distance between a pair of nodes. Experiments demonstrate that the algorithm is superior to a previously proposed method in terms of its ability to compute correct coordinates under a wider variety of conditions and its robustness to measurement errors.