Method and apparatus for receiving a global positioning system signal using a cellular acquisition signal

• US 7,884,762 B2
• Filed: 12/30/2005
• Issued: 02/08/2011
• Est. Priority Date: 06/06/2001
• Status: Expired due to Fees

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Abraham, Charles
• Primary Examiner(s): Issing; Gregory C
• Application Number:
  US11/322,839
• Publication Number:
  US 20060244658A1
• Time in Patent Office: 1,866 Days
• Field of Search: 342/357.15, 342/357.09, 342/357.1, 342/357.14, 455/434
• US Class Current: 342/357.64
• CPC Class Codes: G01S 19/235 Calibration of receiver components
• CPC Class Codes: G01S 19/252 Employing an initial estimate of location in generating assistance data
• CPC Class Codes: G01S 19/256 relating to timing, e.g. time of week, code phase, timing offset
• CPC Class Codes: G01S 19/258 relating to the satellite constellation, e.g. almanac, ephemeris data, lists of satellites in view
• CPC Class Codes: G01S 19/29 carrier including Doppler, related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/34 Power consumption
• CPC Class Codes: H04B 1/3805 with built-in auxiliary receivers

Abstract

Method and apparatus for a GPS device that uses at least one cellular acquisition signal is described. More particularly, a GPS device is configured to receive at least one cellular acquisition signal for obtaining benefits associated with AGPS with only a small subset of AGPS circuitry to interact with a cell phone network. This facilitates use of GPS devices without subscription to a cell phone service provider, thus avoiding cellular subscription fees.

Claims

1. A method for determining position of a Global Positioning System (GPS) handheld device, the method comprising:

obtaining, from a base station in a cellular network, Global Position System Assistance (GPS-A) data without a fee-based subscription to the base station, wherein obtaining GPS-A data without a fee-based subscription further comprises;

detecting a pilot signal of a base station;

decoding a synchronization channel being broadcast by the same base station at a particular offset to a local timekeeping counter;

determining, responsive to the GPS-A data, a position estimate of the GPS handheld device;

acquiring a GPS satellite signal using the GPS-A data.

2. The method of claim 1, further comprising:

computing, responsive to the position estimate, any of a pseudorange and a pseudorange rate.

3. The method of claim 2, further comprising:

determining, based on the GPS-A, a window of delay search for receiving GPS signals, wherein the window of delay search is smaller than a range of possible delays.

4. The method of claim 2, further comprising:

synchronizing, responsive to computing the pseudorange, calculating a coherent averaging of navigation data bits.

5. The method of claim 1, further comprising:

computing, responsive to the position estimate, a pseudorange rate; and

wherein computing responsive to the position estimate further comprises determining a window of frequency search for acquisitioning the GPS satellite signal.

6. The method of claim 1, wherein the GPS-A comprises a location of the base station.

7. The method of claim 1, wherein the GPS-A is a cell identifier of the base station.

8. The method of claim 7, wherein determining the position estimate comprises:

using the cell identifier to obtain a location of the base station from a lookup table having a relationship between the location and the cell identifier.

9. The method of claim 1, wherein the GPSA further comprises a frequency correction burst.

10. The method of claim 9, wherein acquiring the GPS satellite signal further comprises:

determining a frequency offset, based on the frequency correction burst; and

determining a window of frequency search based on the frequency offset, said window of frequency search being smaller than a range of possible frequencies.

11. The method of claim 1, wherein the GPSA further comprises a time synchronization signal.

12. The method of claim 11, further comprising:

determining a timing offset based on the time synchronization signal; and

determining time of day based on the timing offset.

13. The method of claim 1, further comprising:

using said particular offset at which the synchronization channel from the same base station was encoded to compute another time offset; and

using said another time offset computed from the particular offset at which the synchronization channel from the same base station was encoded as an absolute time offset between the local timekeeping counter and GPS time.

14. The method of claim 1, further comprising:

using said particular offset to compute another time offset;

using said another time offset as an absolute time offset between the local timekeeping counter and GPS time if the base station is in a cellular network that is synchronized to GPS time;

using said another time offset and the local timekeeping counter to reduce a delay search window if the base station is in a cellular network that is not synchronized to GPS time.