Reliable anchor node based range-free localization algorithm in anisotropic wireless sensor networks

In the wireless sensor networks, location based applications require an accurate localization algorithm. To estimate location, each normal node, which do not know its own location, uses estimated distances to anchor nodes which have their own location. Hence, the estimation of distance is a key issue in the wireless sensor networks localization. Most previous works assume isotropic networks where approximate the shortest path distances to the Euclidian distances. These approaches cannot obtain accurate distance estimations in anisotropic networks where the shortest path distances are not linearly proportion to the Euclidian distances. In the anisotropic networks, the shortest path between two nodes may be detoured and its length may be estimated much larger than the corresponding Euclidean distance. Because of the phenomenon, it is important to select reliable anchor nodes which offer the precisely estimated distance. In this paper, we propose a reliable anchor node selection algorithm in the anisotropic networks. Each normal node selects the three anchor nodes with Triangular rule to enhance localization accuracy in the proposed algorithm. We also show that our scheme is reasonable through mathematical observation.