Hierarchical Localization of Sensor Network for Infrastructure Monitoring

Abstract

Localization (determination of the position of each sensor node) of a large scale sensor network is an important issue for applying network sensing technique to infrastructure monitoring. This paper presents a concept and an implementation of the hierarchical localization method applicable for large scale sensor network. This system consists of parent nodes with a low priced L1 GPS receiver and child nodes with an acoustic ranging device. Relative positions between child nodes are estimated based on acoustic ranging through a distributed algorithm, called the inverse Delaunay algorithm. This algorithm localizes all the nodes simultaneously; thus, the accumulation of the error in the localization is suppressed. Relatively localized child sensor nodes are given global coordinates with the help of GPS on parent nodes. In spite of its reasonable cost, the robustness and the accuracy of GPS positioning is highly enhanced by using the “almost static” assumption, which is appropriate for infrastructure monitoring. This hierarchical localization method is implemented in a system consisting of off-the-shelf sensor platforms, and field experiments have been conducted for the performance evaluation of the system.