Research On Node Localization Technologies Based On Mobile Anchor Nodes For Wireless Sensor Networks And The Improved Localization Methods

Node localization is the most essential and important technology for Wireless Sensor Networks(WSNs). Most WSNs applications can not work without accurate node localization. Localization technologies by mobile anchor nodes can combine both the advantages of range-based and range-free localization technologies. So nowadays, more and more studies pay attention to the localization technologies by mobile anchor nodes. The localization technologies by mobile anchor nodes and their improved methods are studied in this thesis, and the main contents include:First of all, the localization technologies in WSNs are introduced in detail. Then the basic ideas and implementations of RSSI algorithm, Centroid algorithm, LMAP algorithm and Path Planning algorithms are studied. And their advantages and disadvantages are briefly analyzed.To solve the problem that the localization accuracy of static path planning technologies needs to be enhanced, RSS and Space Broadcast Based Localization Method(RSBB) is proposed in this thesis. Differ from the principle of LMAP(Localization with mobile anchor points in wireless sensor networks), RSBB needn’t detect and estimate the communication edges of sensor nodes. For reducing the algorithm complexity and improving localization accuracy, RSBB directly uses the ratio of RSSI values to estimate the position of the node. The unique sleep mechanism of the sensor nodes contributes to lower energy consumption. The information storage method occupies less memory and reduces the cost.Facing the problem that the static path planning technologies waste lots of anchor node information in the blank area, Dynamic Path Planning Localization Method Based on Orientation Decision(DPOD) is proposed in this thesis. In DPOD localization method, the anchor node uses the directional antenna to collect sensor node information to determine the direction of the next step of the mobile anchor node by a direction decision scheme. The movement follows equilateral triangle principle. The unknown nodes use the three edge localization technologies based on weight selection to localize themselves. And then by the grid incremental optimization technology, DPOD further optimizes the localization. DPOD is designed for networks in which the nodes are distributed inhomogeneous but continuous like U type and Z type. It has higher localization accuracy and the path planning is more flexible.