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Research On Range-free Localization For Wireless Sensor Networks

Posted on:2011-09-01Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y C NiuFull Text:PDF
GTID:1118330332975566Subject:Communication and Information System
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Wireless sensor networks(WSNs) have wide applications in environment monitor-ing, military reconnaissance and resource exploration for its characteristics of large scale, low cost and self-organization. They make a profound change in the interac-tion between people and the nature, and make the universal seamless communication paradigm by anytime and anywhere come true. Localization is one of the supporting technologies in WSNs, which can not only provide the physical locations of events, but also help to improve the routing efficiency, optimize the network coverage and control the topology etc. Therefore, localization problem is one of the key issues in WSNs.From the previous research, it can be noted that the range-based location al-gorithms usually have some limitation when they are applied to large scale WSNs because of the need of special sophisticated devices for distance measurement. Con-sidering the cost and the network size, range-free localization algorithms have many advantages, especially those based on hop counts. They do not need high proportion of anchor nodes and the support by time synchronization. Besides, the protocol is simple and the system scalability is good. However, range-free localization algorithms commonly assume that the WSNs are ideal and isotropic, and ignore the facts that irregular deployment, security attacks and radio irregularity existed in the real WSNs, which affect their performance in real applications. In this dissertation, the solutions based on range-free localization have been proposed for irregular WSNs, and simula-tion experiments for performance evaluation have been conducted. The work of this dissertation is supported by the Natural Science Foundation of China (No.60773182, No.60972010) and National High Technology Research and Development Program of China(No.2007AA01Z241). The main contributions of this dissertation are outlined as follows.(1) Based on the analysis and summary of the main location algorithms in literature, the methods to determine the positions of nodes by the geographic distance are reviewed, and the localization error distribution and the factors that affect the performance in the idealized WSNs are analyzed and compared in detail.(2) A localization algorithm based on topology segmentation (LATS) is proposed for irregular deployment of WSNs. The LATS scheme divides the topology into regularly shaped regions with an adaptive threshold of distance per hop and de-termines the convex hull by computational geometry to localize sensor nodes. Without complicated matrix and iterative calculation, the LATS algorithm per-forms better if both the localization error and computational complexity are considered.(3) A robust localization algorithm against wormhole attack, called ConSetLoc, is proposed for wireless sensor networks, in which neither extra complex encrypting algorithms nor complicated malicious node detection mechanisms are necessary. With the relationship between hop counts and geographic distance, ConSetLoc calculates the range of distance to anchors and designs a partition method of consistent anchors sets by the convex constraints in geometry which can reduce the effect of bad measurements on estimates. A filtering strategy for the candi-date locations is presented. The simulation results demonstrate ConSetLoc can estimate the locations for most of sensor nodes with good accuracy and stability even if wormhole attack exists in the network.(4) A new localization algorithm based on enhanced weighted least square(EWLS) method is proposed for Quasi-UDG model of WSNs. EWLS presents an ana-lytical method to evaluate the hop-distance relationship for Quasi-UDG model where sensor nodes are randomly deployed in a circular region. The border effect and dependence problem are also taken into consideration. With the expres-sions about the distance distribution by a known hop count, the weight for each distance measurement has been designed. Several simulations have been con-ducted and the results show that EWLS can achieve good localization accuracy for Quasi-UDG model.
Keywords/Search Tags:Wireless Sensor Networks, Range-free Localization, Irregular Network Topology, Wormhole Attack, Hop-distance Relationship, Quasi-UDG Model
PDF Full Text Request
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