United States Patent 5,890,068
March 30, 1999
Wireless Location System

Abstract - The position of a Wireless Transceiver (WT) is estimated using the Time Of Arrival (TOA) at several Monitoring Sites (MS) of the signal transmitted by the WT. Several sites are used to solve for the coordinates of the WT using hyperbolic trilateration. A time reference is used to synchronize the Monitoring Sites (MS). Super-Resolution (SR) techniques are applied to increase the resolution of the TOA estimate obtained via correlation of the received signal at each MS. SR techniques can improve the TOA resolution substantially.
Full Patent Information

United States Patent 6,204,812
March 20, 2001
Methods and apparatus to position a mobile receiver using downlink signals, part II

Abstract - The invention consists of methods and apparatus to estimate the position and velocity of a Mobile Receiver (MR) using either the Time Of Arrival (TOA) of signals received by the MR, their Phase Of Arrival (POA), their Strength Of Arrival (SOA), their Frequency Of Arrival (FOA), or a combination thereof, with respect to a reference produced by a Reference Receiver (RR) of known location. In order to solve for the coordinates of the MR, the invention 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 MR, the patent uses FOA based on Frequency Difference Of Arrival (FDOA). An important contribution of this invention is the way the MR receives, processes and combines available signals for location purposes. Another important contribution of this invention is the way the RR receives, processes and combines available signals for reference purposes.
Full Patent Information

United States Patent 6,208,297
March 27, 2001
Methods and apparatus to position a mobile receiver using downlink signals, part I

Abstract - The invention comprises of methods and apparatus to estimate the position and velocity of a Mobile Receiver (MR) using either the Time Of Arrival (TOA) of signals received by the MR, their Phase Of Arrival (POA), their Strength Of Arrival (SOA), their Frequency Of Arrival (FOA), or a combination thereof, with respect to a reference produced by a Reference Receiver (RR) of known location. In order to solve for the coordinates of the MR, the invention 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 MR, the patent uses FOA based on Frequency Difference Of Arrival (FDOA). An important contribution of this invention is the way the MR receives, processes and combines available signals for location purposes. Another important contribution of this invention is the way the RR receives, processes and combines available signals for reference purposes. Yet another important contribution of the invention is the application of Super-Resolution (SR) techniques at both the MR and the RR to increase the resolution of the estimated TOAs, POAs, SOAs, or FOAs.
Full Patent Information

United States Patent 6,266,014
July 24, 2001
Methods and apparatus to position a mobile receiver using downlink signals part IV

Abstract - The invention consists of methods and apparatus to estimate the position and velocity of a Mobile Receiver (MR) using either the Time Of Arrival (TOA) of signals received by the MR, their Phase Of Arrival (POA), their Strength Of Arrival (SOA), their Frequency Of Arrival (FOA), or a combination thereof, with respect to a reference produced by a Reference Receiver (RR) of known location. In order to solve for the coordinates of the MR, the invention 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 MR, the patent uses FOA based on Frequency Difference Of Arrival (FDOA).
Full Patent Information

United States Patent 6,330,452
December 11, 2001
Network-based wireless location system to position AMPs (FDMA) cellular telephones, part I

Abstract - 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.
Full Patent Information