Method and system of a mobile subscriber estimating position

• US 7,602,334 B1
• Filed: 04/03/2008
• Issued: 10/13/2009
• Est. Priority Date: 04/03/2008
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Beceem Communications, Inc. (Broadcom, Inc.)
• Inventors: Lorenz, Robert G.
• Primary Examiner(s): PHAN, DAO LINDA
• Application Number:
  US12/080,639
• Publication Number:
  US 20090251364A1
• Time in Patent Office: 558 Days
• Field of Search: 342/457, 342463-465, 342/357.06, 701/213, 701/215, 455/456.5, 455/456.6
• US Class Current: 342/357.29
• CPC Class Codes: G01S 19/46 the supplementary measurement being of a radio-wave signal type

Abstract

A method and apparatus of a mobile subscriber (MS) estimating position are disclosed. One method includes the MS receiving at least one satellite transmitted signal with a first receiver, and estimating a time of arrival of the at least one satellite transmitted signal. The MS additionally receives at least one terrestrial base station signal with a second receiver, and estimates a time of arrival of the at least one terrestrial base station signal. The MS estimates its position based on the estimated time of arrival of the at least one satellite transmitted signal and the estimated time of arrival of the at least one terrestrial base station signal.

Claims

1. A method of a mobile subscriber (MS) estimating position, comprising:

the MS receiving at least one satellite transmitted signal with a first receiver;

the MS estimating a time of arrival of the at least one satellite transmitted signal;

the MS receiving a plurality of terrestrial base station signals from a plurality of base stations with a second receiver, the MS identifying one of a plurality base stations as a serving base station;

the MS determining a timing offset of the plurality of terrestrial base stations signals through communication with the serving base station;

the MS estimating a time of arrival of each of the plurality terrestrial base station signals;

compensating the estimated time of arrival of each of the plurality of terrestrial base station signals using the timing offset of the corresponding terrestrial base station signal, wherein the timing offset comprises a quantity proportional to the difference between the time of transmission of the terrestrial base station signal and the time of transmission of the received satellite signal;

the MS estimating its position based on the estimated time of arrival of the at least one satellite transmitted signal and the compensated estimated times of arrival of the plurality of terrestrial base station signals.

2. The method of claim 1, further comprising the MS communicating information with only the serving base station.

3. The method of claim 1, further comprising the serving base station of the MS changing as the MS changes physical locations.

4. The method of claim 1, further comprising the MS determining a position of each of the plurality of base stations through communication with the serving base station.

5. The method of claim 1, further comprising the serving base station providing the MS with a neighbor base station advertisement list that the MS uses to identify the plurality of base stations that the MS receives the plurality of terrestrial base station signals.

6. The method of claim 1, further comprising the serving base station providing the MS with a neighbor base station advertisement list that the MS uses to identify other base stations available as serving base stations if the MS changes its physical location.

7. The method of claim 1, wherein the MS uses the plurality of terrestrial base station signals to limit a frequency and code phase search range of the at least one satellite transmitted signal.

8. The method of claim 1, further comprising the serving base station providing the MS with information of satellites the MS is likely to receive the at least one satellite transmitted signal.

9. The method of claim 8, wherein the information of the satellites comprises at least one of navigation data of the satellites, code data of the satellites, satellite visibility, and satellite elevation.

10. The method of claim 9, wherein the navigation data comprises at least one of satellite orbit parameters, satellite clock offset, raw navigation data bits.

11. The method of claim 9, wherein the navigation data comprises raw navigation data bits, and the MS receiving the at least one satellite transmitted signal comprises coherently detecting the navigation data bits for a time duration equivalent to a time duration of the navigation data bits.

12. The method of claim 1, further comprising:

estimating timing and frequency offsets of the MS based on the at least one satellite transmitted signal;

aiding MS acquisition of the plurality of terrestrial base stations signal based on the timing and frequency offsets of the MS.

13. The method of claim 1, further comprising:

estimating timing and frequency offsets of the MS based on the at least one terrestrial base station signal;

aiding MS acquisition of the at least one satellite transmitted signal based on the timing and frequency offsets of the MS.

14. The method of claim 1, wherein estimating the time of arrival of the plurality of terrestrial base station signals comprises:

extracting information from a WiMAX downlink frame preamble.

15. The method of claim 14, wherein extracting information from a WiMAX downlink frame preamble comprises:

determining a channel impulse response of the preamble;

estimating the time of arrival by comparing a peak of the channel impulse response with a pre-estimated start time of the WiMAX downlink frame preamble.

16. The method of claim 15, wherein determining a channel impulse response of the preamble comprises:

performing an FFT on the WiMAX downlink frame preamble;

correlating an output of the FFT with a predetermined PRBS;

performing an IFFT on the correlated output.

17. The method of claim 7, further comprising:

a GPS processor calculating a GPS position using the limited frequency and code phase range.

18. A WiMAX subscriber, comprising:

means for the subscriber receiving at least one GPS signal with a first receiver;

means for the subscriber estimating a time of arrival of the at least one GPS signal;

means for the subscriber receiving a plurality of WiMAX base station signals from a plurality of base stations with a second receiver, the subscriber identifying one of the plurality of base stations as a serving base station;

the subscriber determining a timing offset of the plurality of WiMAX base stations signals through communication with the serving base station;

means for the subscriber estimating a time of arrival of each of the plurality of WiMAX base station signals;

means for compensating the estimated time of arrival of each of the plurality of WiMAX base station signals using the timing offset of the corresponding WiMAX base station signal, wherein the timing offset comprises a quantity proportional to the difference between the time of transmission of the WiMAX base station signal and the time of transmission of the GPS signal;

means for the subscriber estimating its position based on the estimated time of arrival of the at least one GPS signal and the compensated estimated times of arrival of the plurality of WiMAX base station signals.

19. The WiMAX subscriber of claim 18, further comprising:

means for the subscriber using plurality of WiMAX base station signals to limit a frequency and code phase search range of the at least one GPS signal.

20. The WiMAX subscriber of claim 19, further comprising:

a GPS processor calculating a GPS position using the limited frequency and code phase range.