| With the rapid development of the global mobile communication, the demand of the people to the mobile communication business is increasing. Increment business are drawn much attention. Location service (LS) is a hotspot in all these business. Because the location system is applied, the position will be known at anytime and anywhere. It can be used in vehicle navigation and even intelligent transportation system will be constructed. Meanwhile location system can be extended to other fields such as life counseling. Currently, the study in wireless location is not mature. Many problems in the location technology are urgent to be solved. In all these problems, the improvement of the location accuracy is the key.In this paper, the wireless channel environment and the basic location technology are firstly studied. Then more attention is paid to the Non-Line-of-Sight (NLOS) error which is the most key factor which influences the location accuracy. At last, time of arrival (TOA) location algorithm for three base stations (BS), multiple BS united location algorithm and multiple BS dynamic location algorithm are put forward. All these algorithms are based on the basic character of the NLOS error ( NLOS error is always positive in TOA measure). The position of the mobile station is got after finding the center of the TOA geometry model. Through comparison with WLS arithmetic, it proves that all these algorithms mitigate NLOS error efficiently and improve location accuracy actually. At last how to apply The TOA method in the GSM network is discussed. In this part the structure of the GSM is studied, then according to the character of the TOA location measure, some location modules are added in the GSM system. The TOA method for mitigating the NLOS error is implemented. Finally, we compare several methods with the TOA method in GSM network, and the results show that TOA method is an ideal location method in GSM network.
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