Theoretical Research Of Non Line-Of-Sight Ranging And Positioning Technology Based On UWB

In the positioning system, Global Positioning System (GPS) has been widely used in navigation and many other aspects and plays a very important role in them. However, due to the limitation of its own technology, it cannot meet the growing requirements of positioning accuracy. In the complex indoor environments such as residential, office, basement, GPS is not capable of such short range, high-precision positioning. Ultra-wideband has the features that short pulse time, great penetration ability and good time resolution. So it can make up the shortage when localization in the complex indoor environment by GPS. Therefore the ultra-wideband positioning technology which is more suitable for the special environments gets more and more research.There are a lot of obstacles in the complex indoor environments, So the positioning in such poor non-line-of-sight environment cannot be avoided. The problem that serious non-line-of-sight situation draws bigger errors has not been solved completely. So the main research of this paper is the technology of ranging and positioning in non-line-of-sight environment. The ultra-wideband non-line-of-sight positioning system is divided into three modules:ranging module, non-line-of-sight processing module, positioning module. In this paper, these three modules are made a certain amount of research.Firstly in ranging module, ultra-wideband TOA estimation technique is used normally. A TOA estimation threshold compare algorithm combined rms delay and kurtosis is proposed in this paper. The algorithm can obtain a good performance with low complexity. Secondly in non-line-of-sight processing module, we use the method that first to identify the channel state and then to process it. A state identification method based on hypothesis testing is used. What’s more, we only need to focus on the non-coherent reception signal without the accurate channel estimation, and get good differential rate. Finally in the positioning module, by analyzing several traditional positioning algorithms, a weighted least square algorithm based on NLOS identification information is proposed. It shows good positioning effect by comparing these positioning algorithms. Based on the research above, the paper gives a complete ultra-wideband positioning system for the NLOS environment. The results show that it can ensure the positioning accuracy and effectively control the complexity of implementation. By reducing the hardware requirements, it has a high practical value.