| Based on the analysis to domestic and overseas research status of CDMA wireless location techniques, this thesis studies an accurate mobile location method under passive location mode. The passive location technology of CDMA mobile phone locates the object under passive location mode employing a single location station independent of CDMA cellular network. The technology can be directly applied to such branches as public security, safety, customs and border defense, and has potential and important significance on effectively improving the abilities of strengthening information collection, supervising and reconnoitering crime activities.The passive location scheme for mobile phone based on CDMA network is proposed through deep analysis of CDMA2000 1x layer-3 protocols. In this scheme target mobile phone is deceived to report the pilot signal strength measurement message to base station, meanwhile this message is intercepted from air interface by the location station. Associated with the received-signal-strength message of each base station measured by the location station, the accurate position of target mobile phone can be located. As long as the target mobile phone and the location station are in the same or adjacent cell, the location procedure can be implemented without being noticed by user no matter the phone is under normal working or standing by status.Associated with analysis of channel models, the location technology based on signal-strength-difference-of-arrival measurement is investigated. Performances of Fang algorithm and Chan algorithm are evaluated by simulation on MATLAB platform. Focusing on mobile phone signal strength measurement problem, the thesis put some research in fast power measurement algorithm of mobile phone. Finally, the design scheme of this passive location system in CDMA network is put forward with explanation of location principle in detail, and the system architecture and key modules are also defined based on above study. |
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