Investigation On Mobile Station Location In WCDMA-based Cellular Network

Along with the rapid development of the mobile communication technology, more and more subscribers want mobile communications systems to provide location services in recent years. In July 1996 US Federal Communication Commission (FCC) issued the E-911 mandate stating that all carriers of mobile communication must provide the geolocation of an emergency 911 caller to the appropriate public safety answering point. In Oct. 1999 the FCC issued the E-911 Third report and Order, which adopt the revised standards for Phase II location accuracy —For network-based solutions: 100 meters for 67% of callers, 300 meters for 95% of callers. After that, the mobile location technique becomes one of the hottest techniques.Due to a lot of inherent advantages of it, WCDMA has become the main multi access system for the 3th generation mobile communication system. The network-based TDOA location technique is the prevailing location technique in WCDMA system. However, because of the influence of several adverse factors such as multipath, non-line-of-sight propagation, noise, interference and wireless channel frequency characteristics, radio statistics measurements like TDOA, TOA and AOA related to mobile position, the performance of location algorithms may be significantly degraded, and the position estimation of MS is inevitably biased.On one hand, people want to be positioned accurately,on the other hand, people are worried that their location privacy is disclosed improperly. Therefore, in order to focus on the core problem of mobile location accuracy improvement, this thesis aims at TDOA location techniques, and investigates the following cellular network based location techniques: performance analysis of basic TDOA location algorithms, and high accuracy location techniques to mitigate the influence of NLOS, hybrid location algorithms, and location privacy protection.In short, in this thesis, based on the analysis of WCDMA system and location techniques the author's main contributions include:● Present detailedly some leading location methods and compare their respective advantages and disadvantages in accuracy, cost etc,.● The mathematical model of TDOA hyperbolic equations is established, the advantages and disadvantages of several TDOA location algorithms are analyzed in detail.● Compare two methods aiming to mitigate the adverse influence of NLOS and analyse their performances by simulation with MATLAB.● Simulate and analyse a hybrid loation technique based on TDOA/AOA and compare its performance with that of single location technique.● A user location privacy protection policy is proposed.Finally, the WCDMA network architecture with location positioning and basic signaling protocol and interface, and location procedures of WCDMA network mobile location are analyzed.