Mobile Target Passive Localization Technology In Wireless Sensor Network (wsn) Research

Based on the application of wildlife behavior monitoring, we brought wireless sensor network(Wireless Sensor Network, WSN) to monitor the wildlife instead of artificial methods. Meanwhile it can solve the problem of lack of real-time, long-term monitoring. However it is difficult for national endangered wildlife to carry the tag and the scope of its activities are mostly inaccessible places, with complex terrain and ambient noise. Therefore we study the passive object location methods of WSN. However, the existing passive localization methods are mostly applicable to the indoor environments, with intensive deployment, less monitoring points, smaller scales. If we use these methods directly to monitor the wild animals, we will face the following challenges:As the increase of the network size, the number of nodes and the distance between nodes are also increased. How should we ensure the localization accuracy rate under the premise of sparse deployment of the network and monitor the object with fewer nodes and obtain its location and trajectory information effectively.In this paper, we studied how the object affects the Received Signal Strength Indication (RSSI) of single link and constructed the signal symmetry model. On this basis, we studied how to use the multi-link to locate the object’s location. Besides, we studied how to determine the moving object trajectory within a period of time. The specific research work includes the following aspects:1) The object localization method based on single-link detection-Signal Symmetry ModelDividing the covered areas by a single link into different squares, we studied how the object affects RSSI of the received side and what is the RSSI characteristic when object at different locations. Based on the signal diffraction model theory, we analyzed the relationship between the location information and RSSI fluctuations and proposed the signal symmetry properties. Then constructed the localization methods based on the single-link and provide a theoretical basis and guidance for the subsequent sections.2) The object localization method based on the multi-link detection-Unit Detection Model Based on the characteristics of the Signal Symmetric Model, we studied how to establish a multi-link based Unit Detection Model to determine the object location information. According to the collected priori knowledge, we established an object localization model based on Bayesian probability formula. Meanwhile we studied the RSSI distribution relationship between the different vertical lines in the coverage area in order to establish the model of different node distance under fewer sampling points.3) The method of determining the trajectory of the moving objectOn the basis of the Unit Detection Model, we studied how to determine the trajectory of the moving object in a certain period of time. By the establishment of the RSSI b-sequence and r-sequence, we determined the tracking area boundaries and effective Unit Detection Model. Then mine a series of mobile location information of the object.