The Study of Mobile Anchor-Based Localization in Wireless Sensor Networks

• Main Authors: Sheng-Bo Wang, 王聖博
• Other Authors: Chi-Chang Chen
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/wfwek5

碩士 === 義守大學 === 資訊工程學系 === 103 === In this thesis, we propose a scalable path planning algorithm as the trajectory for the mobile anchor in a wireless sensor network. We use Gosper curve, a space filling curve, as a trajectory for the robocar, equipped with GPS, to broadcast location information while travelling to the center of each hexagon along the path. Our approach can ensure that the mobile anchor traverses the entire sensing area uniformly. Meanwhile, we introduce a coordinate system of Gosper Islands for deciding the broadcast position of the mobile anchor, especially when the path has obstacles. If we use the same size of circumscribed circle of radius r for each grid (triangle, square, or hexagon), the anchor node moving path with Gosper curve use less broadcast time, length of moving path, and energy consumption than other methods. For anchor node localization problem in wireless sensor networks, we use trilateration with the least squares method to estimate the positions of unknown nodes. The method of the hexagonal grid arrangement can effectively avoid the anchor node co-linearity. In this thesis, we use the actual measured value of RSSI (Received Signal Strength Indicator) to estimate the distance between anchor node and each unknown node, and the simulations are with one to three times standard deviation of distance errors. Even when we use the maximum value of the standard deviation of RSSI for the distance errors, the location error is only about 4.5% of the transmission distance. It is better than most of the contemporary localization methods.