The Research On Reliable Localization In Wireless Sensor Networks

For many location applications of WSNs(wireless sensor networks), reliable localization is very important for sensor nodes. It is the basis of the normal operation of the location applications. In this dissertation, we focus on the node's secure localization and stable localization in location applications to study the problem of reliable localization. WSNs is an open network, its broadcasting communications enables WSNs face many security threats. How to safely localize the nodes position in an unsafe network environment is the primary problem for reliable localization to be solved. At present, there is a problem for range-free localization algorithms in location-based applications: due to instability of the signal strength, some algorithms have higher localization accuracy but poor stability, other algorithms have better localization stability but bad localization accuracy. How to have better localization stability, and still maintain higher localization accuracy is another problem for reliable localization to be solved.This dissertation focuses on the discussion of secure localization and stable localization of professional applications based on WSNs. The major contents and contributions are as follows:1) Research on measures WSNs secure localization taken, and pointed out the advantages and disadvantages of these measures. Research findings have shown that due to WSNs is an application-oriented network, different applications require different security levels, and face different security threat, so it is difficult to find a common security mechanism to avoid all of the attacks.2) Design and implementation of a symmetric cryptography based localization algorithm. In this dissertation , the impersonating attack is modeled, and its impact on range-free localization algorithms is studied. Also, a symmetric cryptography based scheme is proposed to resist the attack. The experimental results show that, even in the presence of impersonating attack, the scheme decreases the cumulative localization error of Weighted Centroid Algorithm. The probability which the localization error is within 1m can be improved from 40% to 70% with our scheme.3) Design and implementation of an RSSI-based WSNs stable localization algorithm. As to the background of coal mine positioning system, we study the issues about stable localization of mobile nodes. To the best of our knowledge, we first propose the problem of localization stability of range-free localization algorithms. Through sampling RSSI signal several times, discretization the localization results and taking stable localization mechanism, the stability of the Weighted Centroid Algorithm is improved. Also, we implement the stable localization algorithm under MicaZ platform. The experimental results show that, our scheme outperforms the Weighted Centroid Algorithm both in the stability and localization accuracy.