U-tdoa-based Monitoring Network Positioning Technology

Wireless location is receiving increasing attention in the field of wirelee communication. This is due to the order issued by the U.S.Federal Communication Commission that mandates all wireless service providers to locate an emergency 911 caller within a high accuracy. 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.The Ituran system is designed for location of mobile units and two ways data communication. Using self-established bases and adopting U-TDOA technique, it is a real time terrestrial location and monitoring system for efficient Vehicles, People and Cargo management. Its downlink communication protocol is a standard paper POCSAG protocol and Uplink communication is comprised of two separate transmissions: the location link and response link. The location link is a direct sequence, spread spectrum signal. Ituran Location and Control Ltd. Operates the system in Israel, San Paulo, Brazil, several markets in the US and in Buenos Aires. It may take place of GPS in terrestrial location. Combining the map related bases, the system may be applied in LBS.In the paper the composition, the presented methods used for mobile position are studied in detail. Specially, principle and key technologies of the Ituran system are introduced. And it aims at the research of wireless location algorithms based on time-related measurements in Ituran system. After analyzing the previous research in wireless location extensively, the thesis analyzes and compares.by simulation under different environments or different base stations. The simulation results show that, Fang algorithm can achieve good location accuracy in some simulation environment. However, the algorithms must be modified in order to the accuracy demand. Finally, we research its application in Shanghai City ITS Demonstration Project.Many techniques would be concerned in the Ituran System. Furthermore, we will do research in this area in the incoming several years.