Research On Node Localization Algorithm For Wireless Sensor Networks

Wireless Sensor Networks is a new network technology, it integrates sensor technology, micro-electromechanical systems technology, wireless communication technology and distributed information processing technology. Because of its great value, it has great concern by many countries'military departments, industry and academia. Many developed countries have shown great interest in wireless sensor networks. China started late, but due to national attention, we also achieved a lot of results.So far, the development of wireless sensor networks has gone through two stages. The first stage is using MEMS technology to design compact node devices. The second stage is focused on the problem of the network itself. It is also the main directions research on Wireless Sensor Networks currently. On the study of the network itself, the node localization technology is a key condition on applications of wireless sensor networks, and impact on network routing mechanisms, information coverage, load balancing and topology control studies. Node information must be combined with its own location information, only after that it has value. Therefore the study of localization technology has very important significance.This paper reviews the status of localization technology at home and abroad, structure of localization technology, and the node hardware structure. Then discuss several curr- ent popular localization algorithm, and establish a simulation model, introduce node loca- lization algorithm evaluation standard. Selected two representative algorithm APIT and DV-Hop localization algorithm and analyzing these positioning algorithms.APIT is a major non-ranging-based localization algorithm. Relative to other non-Ranging-based Localization Algorithm, APIT has a high positioning accuracy, communication overhead, and so on. However, APIT algorithms require higher density neighbor beacon node, For those neighbors around the anchor nodes, all of the neighbors is less than three or the triangle composed of beacon nodes is not the external triangle of the unknown node, The APIT algorithm will not useful. So it greatly reduces the coverage. In this paper, for the defect, added the cycle refinement to the APIT algorithm, and set of adaptive weights and thresholds. It greatly improves the coverage.DV-Hop algorithm requires low hardware, and simply achieve. But the algorithm may use the jump distance as straight line distance. And the DV-distance algorithm may be affected by ranging error. In order to reduce the impact of nodes ranging error and location algorithm error to the node localization positioning accuracy in wireless sensor network, we established the iterative model based on the Aitken iterative formula for wireless sensor networks. Using the DV-Hop algorithm's results as the initial value, to obtain the optimal value of positioning results. The results shows that the algorithm can improve the accuracy of the node positioning, For the situation of low network node density and low proportion of beacon nodes, Algorithm has an obvious effect.