A NETWORK-BASED WIRELESS LOCATION SYSTEM TO POSITON AMPS (FDMA) CELLULAR TELEPHONES

摘要

The intention of the invention is to produce a network-based Wireless Location System (WLS) whereby existing Advanced Mobile Phone System (AMPs) Frequency Division Multiple Access (FDMA) Cellular Telephones (CTs) can be located passively without modification to the CTs or to the cellular antenna infrastructure. More specifically, the invention consists of methods and apparatus to estimate the position and velocity of a Cellular Telephone (CT) using either the Time Of Arrival (TOA) of a signal transmitted by the CT, its Phase Of Arrival (POA), its Frequency Of Arrival (FOA), or a combination thereof, at several antennas at a number of Monitoring Sites (MSs). In order to solve for the coordinates of the CT, the patent uses either hyperbolic multilateration based on Time Difference Of Arrival (TDOA), or linear multiangulation based on Phase Difference Of Arrival (PDOA), or both. In order to solve for the velocity of the CT, the patent uses FOA based on Frequency Difference Of Arrival (FDOA). An important contribution of this invention is the way the CT is forced to transmit radio signals for location purposes. Another important contribution is the application of Super-Resolution (SR) techniques to increase the resolution of the estimated TOAs, POAs or FOAs. Yet another important contribution is the use of IF-sampling techniques in the receivers at each MS in order to reduce the effect of noise and interference on the accuracy of the WLS.