Researches On Location Estimation Technology Of Mobile Station In Wireless Networks

Due to the wide application of GPS and smart phone, LBS is faced with tremendous growthopportunity in recent years. The core of progressing LBS is to improve the supporting capacity oflocalization. Therefore, research on wireless location technology has important theoretical andpractical significance. This paper mainly studies the wireless location technology based on TDOAand AOA. The main task includes the following aspects:(1)Summarize the status and fundamental of wireless location technology, and NLOS errorsuppressing techniques. Then, several common TDOA positioning algorithms are mainly studiedand simulated.(2)An improved positioning algorithm is proposed in order to resolve the problem of NLOSpropogation. The AOA value is modified by using Bayesian estimation method; meanwhile, basedon Greenstein model, the TDOA values are reconstructed according to channel statistical properties.Finally, the object location is acquired by implementing a single WLS method.(3)Aiming at the positioning problem in three-dimensional field, an improved TDOA/AOAlocation estimation algorithm is studied. The algorithm constructs the three-dimensional form oferror equations. Then, CWLS method is used in the process of location revision in which therelationship between elements of estimation vector is regarded as constraint condition, and it canobtain nice location accuracy.(4)Simulation approach is used to study a new NLOS error mitigation method. Nthorderpolynomial fitting method is adopted to process real measurements. Based on hypothesis testing,LOS/NLOS is identified, and then NLOS measurement results are reconstructed. Simulation showsthat the method can mitigate NLOS error effectively.