A Localization Algorithm Based on the Hops for Large-Scale Wireless Sensor Networks

Localization of sensors is one core technique in wireless sensor networks (WSN). A localization algorithm (BHLA) based on hops for large-scale wireless sensor networks is presented in the paper. In the BHLA algorithm, nodes are divided into anchor nodes and unknown nodes. Unknown node can communicate with the anchor nodes which are covered in this unknown node´ communication range. Firstly, the distance of all anchor nodes to unknown anchor is converted into the number of hops by using Flooding. Then anchor nodes are divided into different areas according to numeric value of their hop, anchor nodes which have same numeric value of hops are belong to the same region. Unknown node collects coordinate information of all anchor nodes, then those coordinate information are divided into different collections according to their region, the coordinate information of the anchor nodes in same region are belong to a same collection. The different coordinate information which belong to those collections can be determined an area by Point In Which Side (PIWS) determination, and the intersection of communication range of all anchor nodes which located in the communication range of unknown node can determine another area. So we can estimate the position of unknown node by the overlapping area of above two areas. The BHLA algorithm is a kind of Range-free algorithm. It also does not need to detect energy. So it can cut down the node energy cost, save time and avoid the interference such as shadow, disorders, attenuation which often be encountered in energy detection. The experiment results illustrate that the BHLA algorithm in this paper has higher accuracy. So it is an effective positioning algorithm.