A Distributed Range-free Localization Algorithm Based on Optimum Distance Derivation in Wireless Sensor Networks

In this paper a distributed range-free localization algorithm based on optimum distance derivation is proposed for three-dimensional wireless sensor networks (WSNs). The algorithm presented in this paper is specified for WSNs in which anchor deployment is very sparse and communication range of each sensor is highly limited. A localization model is designed and evaluated in this paper. Based on this model, the shared relay nodes are formulated in the intersected space for any two sensor nodes within one or two hops. A distance calculation mechanism using the number of shared relay nodes is introduced by the geometrical relationships and probability distributions, which solves the error accumulation and low coverage problem in WSNs. With this mechanism the corresponding distance between any two sensor nodes can be determined using the number of shared relay nodes with minimum errors and high efficiency. Combining with the multi-hop characteristic of the network, unknown nodes establish distance connections with all anchors by hop distances and hop counts, whose final coordinates are then obtained with the least-square approximation. The proposed algorithm only depends on the connection information, which is quite suitable for self-organized Ad-hoc network. Another two different types of anchor node deployment are taken into account in the experiments. Comparisons are made with classic DV-Hop, Centroid and MDS-MAP algorithms. Experimental results prove the proposed algorithm is better in localization accuracy with high efficiency and 100% of localization rate in all parameter settings, as well as low localization cost. The average accuracy improvements in all kinds of circumstances are 74.76%, 79.32%, and 54.47% better compared with the classic DV-Hop, Centroid and MDS-MAP.