Range-free localization with isotropic distance scaling in wireless sensor networks

A number of range-free localization algorithms have been proposed for various applications and approached in wireless sensor networks. Range-free schemes use hop count information of shortest paths between nodes as a distance metric and plus scaling to estimate the physical location. However, since scaling is performed in terms of a single anchor or local topology, location errors can be introduced by scaling. In this paper, we propose a novel range-free localization algorithm to reduce errors in scaling by deriving the optimal scaling factor for one hop with respect to all anchors in the network. The scaling factor can be optimized by minimizing the sum of squares of distance errors between all anchors. We evaluate the proposed algorithm through simulations under a variety of node density and anchor ratio.