Location-based Services In Public Mobile Communications System, The Method Of Implementation

With the development of mobile telecommunication technology, the coverage of public mobile telecommunication system such as wireless cellular network is becoming more and more expansive, and the popularization rate of mobile telephone or mobile station also has been more higher. As well, the rate of emergency calls sent by mobile phone among the whole emergency calls is increasing. However, the aided decision information provided by the modern cellular network to emergency call of mobile phone is scarce. Investigation states 25 percent of mobile user are not aware of their precise position when send out emergency call, which brings enormous restrictions to timely and reasonable responses. So FCC of USA ordered mobile telecommunication network should be able to provide exact position information for mobile users who send out emergency call. from Oct. 1 of 2001.It is very necessary to study the poison of public mobile telecommunication system in a systematic way. The paper discusses the position service of public mobile system in the following aspects: the requirements and applications prospects of public mobile communication system to position services, the position principle and method of public mobile communication system especially cellular network, the present development situation of global satellite navigation system, the business of position service in China public mobile communication system, and the implementation of regional mobile position by the combination of GPS and GSM short message or GSM position information and etc.The paper focuses on how to realize highly efficient mobile position and control management by the combination of GPS position navigation system and the position service, backed up with the existing functions of the second generation mobile telecommunication system,. And also the paper demonstrates how to fulfill the above objectives through field project. During the process of the project, we made some adjustments to the initial plan due to the price fluctuation of hand-held station. We have gained satisfactory position results by multiple channel comparison and time difference measuring. The measuring precision within 20-25 meters can basically satisfy the users' needs, although the precision and AGPS decreased a little after difference conversion to civic level. It is estimated the service will bring annual revenue of 35 to 50 millions to the market (stable users such as automobile position, police control, taxi control, and son on) after put into use in Shenzhen and Guangzhou. At present the service is only used to specific objectives within small scope.