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Research on Localization Technique in Wireless Sensor Networks

Author: YaoYan
Tutor: YuJiGuo
School: Qufu Normal University
Course: Applied Computer Technology
Keywords: Wireless Sensor Networks Localization Algorithm Grid Scan Voronoi Gram
CLC: TP212.9
Type: Master's thesis
Year: 2012
Downloads: 62
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Abstract

With the emergence and rapid development of the Internet of Things (IOT) technology, asone of key technologies of the Internet of Things, wireless sensor networks have been got goodpractice and extension especially in recent years. Wireless sensor networks, which involvingsensor technology, network communication technology, embedded technology, distributedinformation processing technology, microelectronics manufacturing technology, wirelesstransmission technology and so on, are a multi-disciplinary highly cross, emerging frontierresearch field. Wireless sensor networks combining with information collection, communicationand computation ability, can well realize information awareness. It will prove a worthy successorto its previous invention, the World Wide Web, which have significant effects on human’s life.Sensed data without location information is meaningless. As one of the underlyingtechniques for wireless sensor networks, localization technology has very important researchvalue and application prospect. According to whether measuring the practical distance betweennodes in the positioning process, localization algorithm can be divided into two categories:rang-based localization algorithm and range-free localization algorithm. Range-basedlocalization algorithms measure the distance information (such as angle, distance) between thenodes by measurement technology firstly, and then calculate the location of the nodes.Measurement technology usually requires additional hardware to assist to implementmeasurement, which will increase the energy expenditure and hardware cost. However, theirhigh accuracy in localization is very desirable. In order to overcome the shortage of Range-basedlocalization scheme, many Rang-Free localization algorithms have been proposed. According tothe connectivity of the network to estimate the node’s position, without prior measurementinformation between nodes, more accurate than the distance measurement independent ofpositioning technology, and it has low energy consumption.In this paper, we focus on Range-Free localization technology. For large-scale wirelesssensor networks, range-Free localization algorithms have low positioning accuracy and thecoverage rate. We proposed two methods to solve this problem by fowling strategies.1. In grid-scanning based strategy, we analyze the two reasons that caused the locationerror in APIT localization algorithm. And we change the grid scanning strategy,reducing the In-To-Out error, thereby improving the positioning accuracy and coveragerate in large-scale wireless sensor networks. The result is better demonstrated bysimulation.2. The main idea of building virtual anchors using Voronoi diagram scheme is that increase the anchor density without increasing the network energy costs. In general, range-freelocalization algorithms depend on the density of the anchor. The higher with the nodedensity, the better with positioning accuracy and the coverage rate. After nodedeployment, we divide the anchors in the figure using the Voronoi diagram, the verticesof each Voronoi polygon taken as a virtual anchor, called the V-anchor. These V-anchorsdo not participate in the forwarding of information. They only to improve thecoordinates involved in positioning. And the number of network anchor increasedsignificantly. Finally, simulation results show that in large-scale wireless sensornetworks with anchor sparse, the positioning accuracy and coverage rate of thealgorithm have better results.

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