Position location with low tolerance oscillator

• US 20010005680A1
• Filed: 02/01/2001
• Published: 06/28/2001
• Est. Priority Date: 09/09/1998
• Status: Active Grant

• Current Assignee: Gilbert C. Sih, Qiuzhen Zou
• Original Assignee: Gilbert C. Sih, Qiuzhen Zou
• Inventors: Sih, Gilbert C., Zou, Qiuzhen
• Granted Patent: US 6,665,539 B2
• Time in Patent Office: Days
• US Class Current: 455/456.1
• CPC Class Codes: G01S 19/235 Calibration of receiver components
• CPC Class Codes: G01S 19/246 involving long acquisition integration times, extended snapshots of signals or methods specifically directed towards weak signal acquisition
• 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 19/29 carrier including Doppler, related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/30 code related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/37 Hardware or software details of the signal processing chain
• CPC Class Codes: G01S 2205/008 using a mobile telephone network

Abstract

The present invention is a novel and improved method and apparatus for performing position location in wireless communications system. One embodiment of the invention comprises a method of performing position location in a wireless subscriber unit having a local oscillator, including the steps of receiving a position location request, acquiring a timing signal when a sufficient period of time has elapsed since the local oscillator has been corrected and correcting said local oscillator using a correction signal based on said timing signal, substantially freezing the correction signal, performing a position location procedure using the local oscillator with the correction signal applied, and ending said position location procedure.

Claims

1. A method of performing position location in a wireless subscriber unit having a local oscillator, comprising the steps of:

receiving a position location request;

acquiring a timing signal a period of time after the local oscillator had been corrected and correcting said local oscillator using a correction signal based on said timing signal;

substantially freezing the correction signal;

performing a position location procedure using the local oscillator with the correction signal applied; and

ending said position location procedure.

2. The method as set forth in

claim 1

, wherein said timing signal is a pilot signal of a wireless communication system.

3. The method as set forth in

claim 2

, wherein said pilot signal is a CDMA pilot signal.

4. The method as set forth in

claim 2

, wherein said pilot signal is a GSM pilot signal.

5. The method as set forth in

claim 2

, wherein said pilot signal is a TDMA pilot signal.

6. The method of

claim 1

, further comprising the step of entering a communications mode after performing position location procedure.

7. The method as set forth in

claim 1

, wherein said timing signal is a signal from among a set of GSM downlink channels of a GSM wireless communication system.

8. The method of

claim 7

, wherein the set of GSM downlink channels includes an assigned traffic channel mid-amble.

9. The method of

claim 7

, wherein the set of GSM downlink channels includes a GSM frequency correction control channel.

10. The method of

claim 8

, wherein the set of GSM downlink channels further includes a GSM frequency correction control channel.