Needless Ranging Wireless Sensor Network Node Localization Algorithm

Wireless sensor network (WSN) is the hot topic in the present research on information, concerning with many disciplines such as communications technology, embedded technology and sensor technology. Node localization is the core part of wireless sensor networks and many applications need to know the specific location of the node in advance. Generally localization algorithm is divided into range-based algorithm and range-free algorithm according to whether it needs physical measurement to obtain the information about the distance between the nodes or not.Due to the simplicity and low cost of range-free algorithm, it is more suitable for resource-constrained wireless sensor nodes. Therefore, more attentions have been paid to the range-free algorithm. This article focuses on the range-free algorithm of DV-Hop and APIT.Firstly, this paper summarized the node localization technology of WSN. It mainly introduced the related conception of node localization and the basic principles of node localization. In addition, this article also presented the assessment standard of location algorithm and several classical range-free algorithms, and their performance is analyzed. Secondly, the DV-Hop algorithm is deeply discussed and simulation analyzed in this paper. The algorithm requires low node hardware and its implement is simple. However, the algorithm adopts hop distance instead of straight-line distance, which exists biggish error. So this paper adopts a new method to calculate the average hop distance to close to the actual distance, and amends estimation coordinates of unknown node which go beyond the network boundary. MATLAB simulation shows that the improved algorithm can raise the localization accuracy. In addition, APIT localization algorithm is further studied and simulation analyzed. Simulation demonstrates that localization coverage of the APIT algorithm is not high. Also there are lots of nodes that can not be located after the implementation. Therefore, based on analysis of the low coverage rate of APIT, this paper uses Min-max method to locate the nodes that is not concordance with the APIT principle. Compared with the original algorithm, simulation demonstration shows that the algorithm of this paper has been improved obviously, in ensuring the localization accuracy of the premise.