Study On Indoor Localization Algorithm Based On Wireless Sensor Network

Wireless Sensor Network consists of those a large amount of sensor nodes deployed in the monitoring region and self-organized as a network. Localization technology is one of the most important technologies in wireless sensor network. Positon information can help users to relate the collected data with the location where the data are collected. At the same time, the node’s location can also be used by routing protocols or other application layer protocols.Localization algorithms in wireless sensor network can be divided into two categories according to the target of localization. One is the localization of the nodes; the other is the localization of the targets in the monitoring area. Node localization usually needs some anchor nodes which are already deployed in advance. The anchor nodes’ locations are known. Localization of nodes can be done by measuring or estimating the geometric relationships between the nodes whose position is unknown and anchor nodes. The localization of the target can be achieved by mounting the node on the target. In the case of the target without carrying any wireless equipment, the localization can be done by source-free localization.The work of this article mainly focuses on the following three parts:① Research and analysis of the existing node positioning algorithms in wireless sensor network, presenting their advantages and disadvantages, and trying to redesign and improve some existing algorithms, in order to get better positioning accuracy.② Study on the DV-Hop algorithm which is widely used in node localization, analyzing the reason of this algorithm having larger positioning error. According to these reasons, this article improves DV-Hop algorithm. The improvement is reflected in the hop-limit mechanism and the calculation method of hop threshold, the unknown node which has been successfully localized becoming anchor node and the accurate calculation of the hop count between two nodes. According to the improvement scheme,this article presents the detailed algorithm implementation steps and flow chart. Finally, the simulation results show that the improved algorithm can get the correct position information of the unknown node. And compared with the traditional DV-Hop algorithm, in the case of changing the number of anchor nodes, the improved location algorithm has better location accuracy, and its average performance is improved by about 19%.③ The design of an indoor passive location algorithm based on wireless sensor networks has been done. Firstly the experiments about the signal strength between two nodes are carried out in the indoor environment, and the characteristics of signal intensity changes are obtained. Then fingerprint matching positioning technology is used to monitor the area of the pedestrian target. The algorithm takes the signal strength attenuation values as the features of a certain position, and employs the fingerprint matching algorithm to determine the similarity between the current position and the reference point and calculate the target position using the similarity. The experiment results show that the algorithm is simple in computation and can successfully localize the indoor target.