Simplified receiver with rotator for performing position location

• US 6,181,911 B1
• Filed: 09/09/1998
• Issued: 01/30/2001
• Est. Priority Date: 09/09/1998
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Fevrier, Ian J., Kang, Inyup, Sih, Gilbert C., Zou, Qiuzhen
• Primary Examiner(s): Le, Thanh Cong
• Assistant Examiner(s): WYCHE, MYRON
• Application Number:
  US09/150,092
• Time in Patent Office: 874 Days
• Field of Search: 455/12.1, 455/13.2, 455/427, 455/456, 342/357.05, 342/357.06, 342/357.08, 342/357.11, 342/357.12
• US Class Current: 455/12.1
• CPC Class Codes: G01S 19/235 Calibration of receiver components
• CPC Class Codes: G01S 19/24 Acquisition or tracking or demodulation of signals transmitted by the system synchronisation aspects of direct sequence spread spectrum modulation H04B1/7073
• CPC Class Codes: G01S 19/25 involving aiding data received from a cooperating element, e.g. assisted GPS
• 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 19/36 relating to the receiver frond end
• CPC Class Codes: H04B 1/7077 Multi-step acquisition, e.g. multi-dwell, coarse-fine or validation
• CPC Class Codes: H04B 2201/70715 with application-specific features

Abstract

The present invention is a novel and improved method and apparatus for performing position location in wireless communications system. One embodiment comprises a method for performing position location using a set of signals transmitted from a set of satellites including the steps of storing coarse search data, performing a coarse search on said coarse search data for each satellite from said set of satellites, receiving fine search data, performing a set of fine searches on said fine search data, each fine search being performed on a different time segment of said fine search data, and reporting results.

Claims

1. A method for performing position location using a set of signals transmitted from a set of satellites comprising the steps of:

(a) storing coarse search data at a mobile radiotelephone;

(b) performing a coarse search on said coarse search data for each satellite from said set of satellites;

(c) receiving fine search data;

(d) performing a set of fine searches on said fine search data, each fine search being performed on a different time segment of said fine search data;

(d1) using a rotator to correct for doppler irregularities;

(e) reporting results via transmission to an external location.

2. The method as set forth in claim 1 wherein said coarse search is performed over at lower resolution, and said fine search is performed at higher resolution.

3. The method as set forth in claim 2 wherein said fine search is performed over a window centered at offset corresponding to said coarse search results.

4. The method as set forth in claim 1 wherein said each fine search and each coarse search are performed over a duration of samples that corresponds to more than a 10 ms duration.

5. The method as set forth in claim 4 wherein each coarse search is performed over a substantially identical portion of said coarse search data.

6. The method as set forth in claim 1 further wherein said fine search data is deleted after processing, but before said fine search has been completed.

7. The method as set forth in claim 1 wherein said fine searches are performed for each of said satellites.

8. The method of claim 2 wherein said lower resolution is chip×

4 or lower and said higher resolution is chip×

8 or higher.

9. The method of claim 2 wherein said lower resolution is chip×

2 or lower and said higher resolution is chip×

4 or higher.

10. The method as set forth in claim 1 wherein said different time segments overlap.

11. A method for performing position location in a wireless communication system using a set of signals transmitted from a set of satellites comprising the steps of:

(a) collecting approximately 18 ms of lower resolution samples and storing the samples at a mobile radiotelephone;

(a1) using a rotator to correct for doppler irregularities;

(b) performing a set of coarse searches over said lower resolution samples;

(c) computing acquisition codes based on said set of coarse search;

(d) start collecting higher resolution samples;

(e) performing a set of fine searches on said higher resolution samples; and

(f) ending collection of higher resolution samples.

12. The method as set forth in claim 11 wherein step (e) is comprised of the repeatedly performed steps of:

(e.1) adjusting a phase of a sampling clock;

(e.2) performing a fine search for a signal from one satellite.

13. The method as set forth in claim 11 wherein said lower resolution samples are chip×

2 samples.

14. The method as set forth in claim 11 wherein said higher resolution samples are chip×

8 samples.

15. The method as set forth in claim 11 further comprising the step of transmitting reverse link frames containing position location information based on said higher resolution samples to a base station.