System and method for locating a mobile unit within the service area of a mobile communications network

• US 6,748,226 B1
• Filed: 12/23/1998
• Issued: 06/08/2004
• Est. Priority Date: 11/16/1994
• Status: Expired due to Fees

• Current Assignee: Future Capital L.L.C. (Intellectual Ventures LLC)
• Original Assignee: Minorplanet Systems USA, Inc. (Remote Dynamics Incorporated)
• Inventors: Wortham, Larry C.
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): SOBUTKA, PHILIP
• Application Number:
  US09/219,113
• Time in Patent Office: 1,994 Days
• Field of Search: 455/456, 455/457, 455/414, 455/422, 455/426, 455/517, 455/434, 455/440, 455/575, 455/515, 455/456.1, 455/456.2, 455/456.6, 342/357.1, 342/450, 342/451, 342/457, 342/463, 342/464, 342/389
• US Class Current: 455/456.6
• CPC Class Codes: G01S 11/08 using synchronised clocks
• CPC Class Codes: G01S 19/071 DGPS corrections
• CPC Class Codes: G01S 19/41 Differential correction, e.g. DGPS [differential GPS]
• CPC Class Codes: G01S 5/009 Transmission of differential positioning data to mobile
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A differential positioning system (10) includes components of a satellite-based or land-based positioning system (12) and components of a mobile communications network (14). The differential positioning system (10) provides accurate and immediate position information to a mobile unit (17). A transmitter site (40) of a mobile communications network (14) is associated with a reference positioning receiver (38). The reference positioning receiver (38) generates correction data for transmission to the mobile unit (17). The mobile unit (17) includes a mobile communications device (42) for receiving the correction data generated by the reference positioning receiver (38) and a mobile positioning receiver (24) for generating a position fix. The mobile unit (17) refines the position fix generated by the mobile positioning receiver (24) using correction data received by the mobile communications device (42).

Claims

1. A system for locating a mobile unit within the service area of a mobile communications network, comprising:

a plurality of transmitter sites operable to transmit time-of-arrival data independent of periodic timed pulses, wherein the time-of-arrival data contains the precise time of transmission of the time-of-arrival data from the transmitter sites;

a mobile communications device on the mobile unit and operable to receive time-of-arrival data transmitted by at least three transmitter sites;

a memory operable to store known position coordinates of the transmitter sites; and

a processor coupled to the mobile communications device and the memory, the processor operable to determine the position of the mobile unit in response to the time-of-arrival data and the known position coordinates of the transmitter sites.

2. The system of claim 1, wherein each transmitter site transmits time-of-arrival data using a control channel of the mobile communications network.

3. The system of claim 1, wherein the transmitter sites are associated with a cellular telephone system.

4. The system of claim 1, wherein the transmitter sites simultaneously transmit time-of-arrival data.

5. The system of claim 1, wherein the processor is operable to determine the position of the mobile unit using triangulation techniques.

6. The system of claim 1, wherein the transmitter sites furnish time-of-arrival data in response to a request by the mobile unit.

7. The system of claim 1, wherein the processor is further operable to:

determine the time of reception of the time-of-arrival data by the mobile communications device;

determine pseudorange measurements based upon the difference between the time of transmission and the time of reception of the time-of-arrival data; and

determine the position of the mobile unit based upon the pseudorange measurements.

8. The system of claim 1, further comprising a clock coupled to the transmitter sites, the clock operable to synchronize the transmission of time-of-arrival data from the transmitter sites.

9. A system for locating a mobile unit within the service area of a mobile communications network, comprising:

a plurality of transmitter sites, each transmitter site operable to transmit time-of-arrival data independent of periodic timed pulses and mown position coordinates associated with the transmitter site, wherein the time-of-arrival data contains the precise time of transmission of the time-of-arrival data from the transmitter sites;

a mobile communications device on the mobile unit and operable to receive time-of-arrival data and known position coordinates transmitted by at least three transmitter sites; and

a processor coupled to the mobile communications device, the processor operable to receive the known position coordinates from the mobile communications device, the processor further operable to determine the position of the mobile unit in response to the time-of-arrival data and the known position coordinates.

10. The system of claim 9, wherein each transmitter site transmits time-of-arrival data and known position coordinates of the transmitter site using a control channel of the mobile communications network.

11. The system of claim 9, wherein the transmitter sites are associated with a cellular telephone system.

12. The system of claim 9, wherein the transmitter sites simultaneously transmit time-of-arrival data and known position coordinates.

13. The system of claim 9, wherein the controller is operable to determine the position of the mobile unit using triangulation techniques.

14. The system of claim 9, wherein the transmitter sites furnish time-of-arrival data and known position coordinates in response to a request by the mobile unit.

15. The system of claim 9, wherein the processor is further operable to:

determine the time of reception of the time-of-arrival data by the mobile communications device;

determine pseudorange measurements based upon the difference between the time of transmission and the time of reception of the time-of-arrival data; and

determine the position of the mobile unit based upon the pseudorange measurements.

16. The system of claim 9, further comprising a clock coupled to the transmitter sites, the clock operable to synchronize the transmission of time-of-arrival data and known position coordinates from the transmitter sites.