Auxiliary system for assisting a wireless terminal in determining its position from signals transmitted from a navigation satellite

• US 6,281,837 B1
• Filed: 04/06/2000
• Issued: 08/28/2001
• Est. Priority Date: 09/11/1997
• Status: Expired due to Term

• Current Assignee: RPX Corporation
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Vannucci, Giovanni, Richton, Robert Ellis
• Primary Examiner(s): PHAN, DAO LINDA
• Application Number:
  US09/544,415
• Time in Patent Office: 509 Days
• Field of Search: 342/357.1, 342/357.06, 342/357.09, 342/357.05, 701/213, 701/215, 375/200, 375/208
• US Class Current: 342/357.42
• CPC Class Codes: G01S 19/235 Calibration of receiver components
• CPC Class Codes: G01S 19/254 relating to Doppler shift of satellite signals
• 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 2205/008 using a mobile telephone network
• CPC Class Codes: G01S 5/0027 of actual mobile position, i.e. position determined on mobile
• CPC Class Codes: G01S 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station
• CPC Class Codes: G01S 5/0063 of measured values, i.e. measurement on base station and position calculation on mobile
• CPC Class Codes: H04B 7/18552 using a telephonic control signal and a second ranging satellite determining absolute distances from a plurality of spaced points of known location G01S5/14

Abstract

A wireless terminal and auxiliary system are disclosed that enable the wireless terminal to determine its location based on signals transmitted from navigation satellites. In particular, the tasks of signal acquisition and signal processing required of a wireless terminal in the prior art are divided between the wireless terminal and the auxiliary system in accordance with the illustrative embodiment. The auxiliary system assists the wireless terminal by acquiring information about the satellites'"'"' ephemerides, by partially processing it and by transmitting the partially processed information to the wireless terminal in a form that is useful to the wireless terminal. The wireless terminal then uses the partially processed information from the auxiliary system to assist the wireless terminal in acquiring the ranging signals from the navigation satellites quickly and when they are weak.

Claims

1. An auxiliary system comprising:

a timing signal receiver for generating a system timing signal;

a satellite positioning system receiver for receiving a signal from a satellite;

a Doppler shift estimator for generating a Doppler shift estimate; and

a telecommunications transmitter for transmitting said system timing signal and said Doppler shift estimate to a wireless terminal over a wireless telecommunications link.

2. The auxiliary system of claim 1 further comprising:

a demodulator for generating a modulation bit sequence;

wherein said telecommunications transmitter also transmits said modulation bit sequence to said wireless terminal.

3. The auxiliary system of claim 1 further comprising:

a PRN code synchronization estimator for generating a PRN code synchronization estimate based on said signal;

wherein said telecommunications transmitter also transmits said PRN code synchronization estimate to said wireless terminal.

4. The auxiliary system of claim 1 further comprising a coarse location estimator for generating a coarse location estimate of said wireless terminal and wherein said PRN code synchronization estimate is based on said signal and said coarse location estimate.

5. The auxiliary system of claim 1 further comprising:

a receiver for receiving a partially processed ranging signal from said wireless terminal; and

means for determining a location of said wireless terminal based on said partially processed ranging signal.

6. The auxiliary system of claim 1 further comprising a receiver for receiving a location of said wireless terminal from said wireless terminal.

7. The auxiliary system of claim 6 further comprising means for using said location of said wireless terminal in a location-based service.

8. An auxiliary system comprising:

a satellite positioning system receiver for receiving a first signal from a satellite;

a Doppler shift estimator for generating a Doppler shift estimate of a second signal that is received by a wireless terminal from said satellite based on said first signal; and

a telecommunications transmitter for transmitting said Doppler shift estimate to said wireless terminal over a wireless telecommunications link.

9. The auxiliary system of claim 8 further comprising a PRN code synchronization estimator for generating a PRN code synchronization estimate, and wherein said telecommunications transmitter also transmits said PRN code synchronization estimate to said wireless terminal.

10. The auxiliary system of claim 8 further comprising a demodulator for generating a modulation bit sequence, and wherein said telecommunications transmitter also transmits said modulation bit sequence to said wireless terminal.

11. The auxiliary system of claim 8 further comprising a timing signal receiver for generating a system timing signal, wherein said telecommunications transmitter also transmits said system timing signal to said wireless terminal.

12. The auxiliary system of claim 8 further comprising a coarse location estimator for generating a coarse location estimate of said wireless terminal and wherein said Doppler shift estimate is based on said first signal and said coarse location estimate.

13. The auxiliary system of claim 8 further comprising:

a receiver for receiving a partially processed ranging signal from said wireless terminal; and

means for determining a location of said wireless terminal based on said partially processed ranging signal.

14. The auxiliary system of claim 8 further comprising a receiver for receiving a location of said wireless terminal from said wireless terminal.

15. The auxiliary system of claim 14 further comprising means for using said location of said wireless terminal in a location-based service.

16. A method comprising:

generating a system timing signal with a timing signal receiver;

receiving a signal from a satellite with a satellite positioning system receiver;

generating a Doppler shift estimate based on said signal with a Doppler shift estimator; and

transmitting said timing signal receiver and said Doppler shift estimate to a wireless terminal over a wireless telecommunications link.

17. The method of claim 16 further comprising:

generating a modulation bit sequence based on said signal with a demodulator; and

transmitting said modulation bit sequence to said wireless terminal.

18. The method of claim 16 further comprising:

generating a PRN code synchronization estimate based on said signal with a PRN code synchronization estimator; and

transmitting said PRN code synchronization estimate to said wireless terminal.

19. The method of claim 16 further comprising generating a coarse location estimate of said wireless terminal with a coarse location estimator, and wherein said PRN code synchronization estimate is based on said signal and said coarse location estimate.

20. The method of claim 16 further comprising:

receiving a partially processed ranging signal from said wireless terminal; and

determining a location of said wireless terminal based on said partially processed ranging signal.

21. The method of claim 16 further comprising receiving a location of said wireless terminal from said wireless terminal.

22. The method of claim 21 further comprising using said location of said wireless terminal in a location-based service.

23. A method comprising:

receiving a first signal from a satellite with a satellite positioning system receiver;

generating a Doppler shift estimate of a second signal that is received by a wireless terminal from said satellite based on said first signal with a Doppler shift estimator; and

transmitting said Doppler shift estimate to said wireless terminal over a wireless telecommunications link.

24. The method of claim 23 further comprising:

generating a PRN code synchronization estimate with a PRN code synchronization estimator; and

transmitting said PRN code synchronization estimate to said wireless terminal.

25. The method of claim 23 further comprising:

generating a modulation bit sequence with a demodulator; and

transmitting said modulation bit sequence to said wireless terminal.

26. The method of claim 23 further comprising:

generating a system timing signal with a timing signal receiver; and

transmitting said system timing signal to said wireless terminal.

27. The method of claim 23 further comprising generating a coarse location estimate of said wireless terminal with a coarse location estimator, and wherein said Doppler shift estimate is based on said first signal and said coarse location estimate.

28. The method of claim 23 further comprising:

receiving a partially processed ranging signal from said wireless terminal; and

determining a location of said wireless terminal based on said partially processed ranging signal.

29. The method of claim 23 further comprising receiving a location of said wireless terminal from said wireless terminal.

30. The method of claim 29 further comprising means for using said location of said wireless terminal in a location-based service.