Investigation Of Mobile Station Location Techniques Based On SSOA For GSM Network

With the development of mobile communication technology, the coverage rate of mobile phone has been more and more higher. Location techniques are playing an important role in dealing with emergency calls and helping the public safety department beat the criminal using the mobile phone. But in term of the technical specification of GSM Phase2+ about LCS (Location Services), the current location systems based on GSM network have their inherent disadvantages. For example, the mobile phone must have some location functions to support the location services, on the other hand, the authentication and authorization between the mobile phone and the GSM network location system are necessary, and these intensively limit the usage of this system.Based on the research status analysis of domestic and international relevant location techniques and aiming at the disadvantages of current network location systems, the thesis mainly investigates mobile station location technique based on SSOA(Signal Strength of Arrival) in GSM network and the scheme of single station location system using the technique is proposed. This location system pages the target mobile station and stops the paging signalling before the target mobile station sends the alert signalling to the base station, during this time, through the mobile radio interface(Um)the location system can capture the power measurement report which the target mobile station sends to the base station on uplink channel SACCH, then translate the measurement report into the distance information and estimate the mobile position with designed special location algorithms, at last determine the position of target mobile stations without the cooperation of the GSM base station.Focusing on the requirements of single station location technique, the thesis mainly analyzes and discusses the GSM system framework, mobile radio interface technology and relevant technical specifications. The thesis analyzes the physical and logic channel to carry the power measurement report in the air interface, the formatand period of the power measurement report, and how to deal with the power measurement report in a calling procedure. To demonstrate the possibility and feasibility of this location technique, the actual calling procedures have been rebuilt by the use of DT software. Based on the analysis of channel models, the location performances of an AWC location algorithm and the traditional Fang algorithm are evaluated by simulation on MATLAB platform. Finally, based on above study, the design scheme of this location system in actual GSM network is put forward, the localizing principle of the location system is demonstrated, and the system composition and key modules are also defined.