Research On Cooperative Localization Technique With Ubiquitous Signals In Wireless Network

With the rapid development of data and multimedia services, the demand for navigation and location has been increasing, especially in space-constrained environments, such as indoor environment, railway tunnel and subway. In these environments, due to the global satellite navigation signals can’t be covered, the precision that location-based services can be obtained is generally low. Meanwhile, the ubiquitous cooperative location technology in wireless network becomes the research hotspot in the field of localization duo to the restrictive of measurement errors and complex environmental conditions in space-constrained environments.Through the review of ubiquitous wireless location research status and relevant literature, three major research directions are studied in this paper:the multipath-aided cooperative location technology in indoor environment, the data fusion location technology based on improved location algorithm and the relay location technology in railway tunnel scenarios. The research and innovation points are as follows.1. This paper presents a multipath-aided cooperative location technology in case of one anchor node in indoor environment. In the process of indoor multipath propagation, the unknown nodes which can communicate directly with the anchor nodes utilize the LPMD (Line of Possible Mobile Device Location) to achieve location. The other unknown nodes utilize multipath-aided cooperative location technology to exchange location information, and obtain the estimation of location and accuracy by using of belief propagation. The simulation results show that the cooperative location algorithm can improve location accuracy significantly and reduce the node deployment costs compared with non-cooperative location algorithm.2. Based on improved RSSI (Received Signal Strength Indication) algorithm and improved LPMD algorithm, an enhanced data fusion-based location method is proposed to determine the location of indoor mobile terminal.Firstly, this location technology takes the effect on the RSSI by the building.penetration loss into account, and then detects and removes the multiple reflection paths. Secondly, measurement results use the unscented kalman filter to reduce the influence of noise. Finally, data fusion algorithm based on adaptive weight is proposed to fuse the location results of two improved algorithms. The simulation results show that the proposed data fusion location algorithm can both track and locate moving target effectively and improve the location accuracy.3. In the railway tunnel scenario, the technical solution of "relay location" is proposed in this paper which means that the absolute position of the mobile terminal in train is equal to the absolute position of the train plus the relative position between the train and the mobile terminal in train. The absolute position of the train can be obtained by arranging anchor nodes in railway tunnel, and the relative position between the train and the mobile terminal in train can be solved through the traditional indoor location algorithm. Simulation results show that the relay location algorithm can get the absolute position estimate of mobile terminal in train effectively.