Study On Wireless Location Technique In CDMA System

Since the United States Federal Communications Commission (FCC) issused the E-911 mandatory stating in 1996 that all wireless carriers must provide the geolocation of an emergency caller to the appropriate public safety answering point, wireless location technique has developed very rapidly. Applications for the location of subscribers of wireless services continue to be expanded. In addition to security service, the mobile station's position can be applied to information services, network performance enhancement, more effective resource management and location-sensitive billing.Due to a lot of inherent advantages of it, CDMA have become the main multi access method for the third generation mobile communication system. So technologies based on CDMA system attracted more and more attention. In this dissertation, the forward-link position location technology for CDMA system is studied. Furthermore, a mobile location simulor is designed and an effective location method is also presented to mitigate the influence of the NLOS propagation.First, the basic principles of wireless location and adopted location technologies for all mobile communication systems are introduced in this paper. We mainly analyze and summarize the methods used in CDMA system, including reverse-link location, forward-link location, netwoerk architecture and procedures. Second, a mobile positioning simulor based on IS-95 forward-link is designed, which consists of three parts: signal transmission, channel model and signal receiving module. In these parts, we lay great stress on how to implement channel model. Then the simulation test on TDOA technique has been made and theresults have been analyzed. At last, aiming at non-line-of-sight (NLOS) propagation problem, this thesis proposes a location algorithm for mitigating the influence of it. Integrating decision and NLOS error mitigation, the proposed method is verified to evidently improve location performance by the simulation results.