Communication network intialization apparatus and method for fast GPS-based positioning

• US 6,400,319 B1
• Filed: 03/29/2000
• Issued: 06/04/2002
• Est. Priority Date: 09/01/1998
• Status: Expired due to Term

• Current Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Original Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Inventors: Castelloe, Michael, Lamkin, Allan, Noerpel, Anthony, Roos, Dave
• Primary Examiner(s): PHAN, DAO LINDA
• Application Number:
  US09/538,050
• Time in Patent Office: 797 Days
• Field of Search: 342/352, 342/357.01, 342/357.08, 342/357.05, 342/457, 455/456, 455/457
• US Class Current: 342/457
• CPC Class Codes: G01S 19/05 providing aiding data
• CPC Class Codes: G01S 19/06 employing an initial estimate of the location of the receiver as aiding data or in generating aiding data
• CPC Class Codes: G01S 19/10 providing dedicated supplementary positioning signals
• CPC Class Codes: G01S 2205/008 using a mobile telephone network

Abstract

An apparatus and method is disclosed, utilizing a communications network (in this particular design, it is a GEM (Geo-Mobile) satellite system) to initialize a Global Positioning System (GPS) receiver (such one integrated into a handheld user terminal, or phone used within the communication network) to enable the GPS receiver to quickly acquire GPS satellite signals and perform positioning calculations. By systematically feeding the GPS receiver key pieces of information (GPS satellite trajectories, time estimate, position estimate, and additional positional references), the time to first fix (TTFF) of the GPS receiver can be drastically reduced.

Claims

1. A method for estimating the location of a receiver of a satellite-based communications system, comprising the steps of:

receiving at said receiver a respective broadcast channel of at least one of a plurality spot beams projected by at least one satellite of said communications system, each said spot beam covering a respective area of the surface of the earth;

measuring a respective received power level for each said respective broadcast channel received at said receiver;

evaluating each said respective received power level to estimate a location of said receiver relative to substantially any location within said at least one spot beam; and

estimating a location of said receiver on the surface of the earth based on a relative position of said estimated location of said receiver.

2. A method as claimed in claim 1, wherein:

said receiving step receives at said receiver a said respective broadcast channel from each of a plurality of said spot beams,

said measuring step measures a respective received power level for each said respective broadcast channel received at said receiver; and

said evaluating step compares said received power levels to estimate a location of said receiver relative to at least one location within at least one of said spot beams.

3. A method as claimed in claim 2, wherein:

said evaluating step compares said received power levels to estimate said location of said receiver relative to a respective said location within each respective one of said spot beams.

4. A method as claimed in claim 2, wherein:

said evaluating step compares a plurality of the strongest received power levels to estimate said location of said receiver.

5. A method as claimed in claim 1, further comprising the step of:

representing at least one said respective area covered by said at least one spot beam in a two-dimensional plane; and

wherein said evaluating step estimates a location of said receiver relative to at least one location within said at least one of said spot beam as represented in said two-dimensional plane.

6. A method as claimed in claim 5, wherein:

said representing step represents in said two-dimensional plane at least one of said respective area covered by one of said spot beams whose respective broadcast channel was received by said receiver at a respective power level which is among the strongest received power levels.

7. A method as claimed in claim 5, wherein:

said estimating step estimates said location of said receiver on the surface of the earth based on a relative position of said estimated location of said receiver as represented in said two-dimensional plane.

8. A method as claimed in claim 5, wherein:

said representing step represents each of a respective area covered by each of a plurality of said spot beams in a two-dimensional plane; and

said evaluating step estimates a location of said receiver relative a respective said location within each of said respective spot beams as represented in said two-dimensional plane.

9. A method as claimed in claim 1, wherein:

said receiving step receives at said receiver a respective broadcast control channel as said respective broadcast channel; and

said measuring step measures a respective received power level for each said respective broadcast control channel received at said receiver.

10. A system for estimating the location of a terminal of a satellite-based communications system, comprising:

a receiver, disposed at said terminal and adapted to receive a respective broadcast channel of at least one of a plurality of spot beams projected by at least one satellite of said communications system, each said spot beam covering a respective area of the surface of the earth;

an evaluator, adapted to measure a respective received power level for each said respective broadcast channel received at said receiver, and to evaluate each said respective received power level to estimate a location of said terminal relative to substantially any location within said at least one spot beam; and

a location estimator, adapted to estimate a location of said terminal on the surface of the earth based on a relative position of said estimated location of said terminal.

11. A system as claimed in claim 10, wherein:

said receiver is adapted to receive a said respective broadcast channel from each of a plurality of said spot beams,

said evaluator is further adapted to measure a respective received power level for each said respective broadcast channel received at said receiver, and to compare said received power levels to estimate a location of said terminal relative to at least one location a within at least one of said spot beams.

12. A system as claimed in claim 11, wherein:

said evaluator is further adapted to compare said received power levels to estimate said location of said terminal relative to a respective said location within each respective one of said spot beams.

13. A system as claimed in claim 11, wherein:

said evaluator is further adapted to compare a plurality of the strongest received power levels to estimate said location of said terminal.

14. A system as claimed in claim 10, further comprising:

a translator, adapted to represent at least one said respective area covered by said at least one spot beam in a two-dimensional plane; and

where in said evaluator is further adapted to estimate a location of said terminal relative to at least one location within said at least one of said spot beam as represented in said two-dimensional plane.

15. A system as claimed in claim 14, wherein:

said translator is further adapted to represent in said two-dimensional plane at least one of said respective area covered by one of said spot beams whose respective broadcast channel was received by said receiver at a respective power level which is among the strongest received power levels.

16. A system as claimed in claim 14, wherein:

said location estimator is further adapted to estimate said location of said terminal on the surface of the earth based on a relative position of said estimated location of said terminal as represented in said two-dimensional plane.

17. A system as claimed in claim 14, wherein:

said translator is further adapted to represent each of a respective area covered by each of a plurality of said spot beams in a two-dimensional plane, and

said evaluator is further adapted to estimate a location of said terminal relative a respective said location within each of said respective spot beams as represented in said two-dimensional plane.

18. A system as claimed in claim 10, wherein:

said receiver is further adapted to receive a respective broadcast control channel as said respective broadcast channel; and

said evaluator is further adapted to measure a respective received power level for each said respective broadcast control channel received at said receiver.