Research Of Device-Free Passive Localization With Wireless Sensor Network

Device-free Passive (DfP) localization with wireless sensor network is a system envisioned to detect, track, and identify entities that do not carry any device, nor participate actively in the localization process. In this paper, Radio Tomography Imaging (RTI), an emerging technology for imaging passive objects is discussed. The essence of RTI is to infer positions of targets within the wireless sensor network coverage area by reconstructing images of the shadow fading distribution. However, before that, the weighting of pixel which can tell how the link shadow fading occurs in the wireless sensor network coverage area, needs to be determined. Based on an elliptical model, this paper proposes an improved weight model, which is more in line with the actual situation. And meanwhile, both simulations and experiments verify that the improved model is more effective, and can enhance the accuracy of positioning.In this paper, the contribution includes the following:(1) The shadow fading characteristics in wireless sensor network are studied through analyzing the relationship between target occlusions and received signal strength RSS, which can provide a foundation for the following research.(2) Based on the above analyzed results and the existing weight model named as Model B in this paper, an improved weight model named as Model C, which is more in line with the actual situation, is proposed, and then verified through simulations.(3) Using the real received signal strength RSS data, this paper applies the above two weight models to carry out single target and dual targets positioning respectively. Experiments show that Model C not only is feasible and valid, but also can decrease the positioning error and enhance the positioning accuracy.(4) This paper utilizes different methods for data processing, as well as different image reconstruction algorithms to achieve target positioning. In addition, in order to provide a reference for choosing reasonable parameters for target positioning, this paper studies how introduced parameters affect the positioning accuracy. (5) This paper designs a platform for device-free passive localization to achieve real time displaying the location of single target based on the estimated location of single target at any time.