Research On The Key Technology Of WSNs Node Localization

With the development of Wireless Sensor Network, it can be applied in many circumstances. Its functions are more and more various. In many applications,nodes'positions need to be known. It is essential that node can execute localization in many applications. Recently, most applications use localization methods based on GPS. It is inappropriate that all the nodes equip GPS device because of high cost. Thus, nodes equipped with GPS locate the nodes without GPS. Localization can be classified range-based algorithm and range-free algorithm according to localization mode. In this paper, DV-Hop localization algorithm which is most familiar and important one in range-free localization algorithm is discussed. Many scholars have studied the DV-Hop algorithm. This paper studied the following two problems based on the existing research results.Firstly, an improved DV-Hop algorithm for enhancing localization accuracy is proposed in view of DV-Hop low localization accuracy. DV-Hop does not use straight-line distance but hop distance when calculates the distance between anchor nodes and unknown nodes,which makes errors appearance. The improved DV-Hop algorithm calculates global average per-hop distance and global average per-hop error,and regards the difference of two variables as corrected average per-hop distance. Then, the corrected value is adopted when the hop between anchor node and unknown node is larger than 1. Average per-hop distance is used if the hop between anchor node and unknown node is 1. Simulation results show that the improved DV-Hop algorithm can reduce the localization error and enhance the accuracy of sensor nodes localization more effectively.Secondly, a security DV-Hop localization algorithm against wormhole attack is proposed on the basis of the improved algorithm. DV-Hop algorithm is vulnerable to the wormhole attack because of algorithm characteristics. Two wormhole detection methods were proposed to resist wormhole attack. They are the method based on neighbors of anchor nodes and the method based on communication radius of anchor nodes. In the method based on neighbors of anchor nodes, anchor nodes estimate the number of nodes in the communication range. The method compares the estimation number with receiving value of one hop message. It can be determined that there is wormhole attack in network if two values are quite different. In the method based on communication radius of anchor nodes,nodes detect wormhole according the size relationship between actual distance of two nodes and communication radius. After finding wormhole in network, anchor nodes estimate the location of wormhole nodes based on voting mechanism. Simulation results show that the proposed methods can detect and locate wormhole with high probability.