Recovery from position and time outliers in positioning

• US 9,423,505 B2
• Filed: 12/14/2011
• Issued: 08/23/2016
• Est. Priority Date: 12/15/2010
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Riley, Wyatt Thomas, Daita, Lalitaprasad V., Morrison, William James, Farmer, Dominic Gerard, Wu, Jie
• Primary Examiner(s): McGue, Frank J
• Application Number:
  US13/325,649
• Publication Number:
  US 20120182182A1
• Time in Patent Office: 1,714 Days
• Field of Search: 342/357.58, 342/357.28
• US Class Current: 1/1
• CPC Class Codes: G01S 19/20 Integrity monitoring, fault detection or fault isolation of space segment
• CPC Class Codes: G01S 19/25 involving aiding data received from a cooperating element, e.g. assisted GPS
• CPC Class Codes: G01S 19/252 Employing an initial estimate of location in generating assistance data
• CPC Class Codes: G01S 19/396 Determining accuracy or reliability of position or pseudorange measurements
• CPC Class Codes: G01S 19/45 by combining measurements of signals from the satellite radio beacon positioning system with a supplementary measurement

Abstract

A mobile device may use one or more outlier detectors to detect likelihoods that an outlier condition exists for a satellite positioning system (SPS) position fix. In some implementations, an outlier detector may compare a computed position fix to an element of assistance data to generate an outlier likelihood. A decision to perform a recovery operation may be made based, at least in part, on a generated outlier likelihood. In some implementations, a computed reliability of the position fix may also be considered in making a recovery decision.

Claims

1. A processor implemented method comprising:

starting a first process to obtain a first position fix comprising an estimated location of a mobile device based, at least in part, on signals acquired from one or more satellite transmitters of a satellite positioning system utilizing one or more receivers at said mobile device, said first process comprising application of one or more assistance parameters;

detecting an erroneous condition in a computation of said estimated location of said mobile device based, at least in part, on a comparison of said estimated location with an initial position of said mobile device;

in response to said detection of said erroneous condition, and based, at least in part, on a computed reliability of said first position fix, starting a second process at said mobile device to obtain a second position fix based, at least in part, on one or more second satellite signals acquired from one or more satellite transmitters of said satellite positioning system utilizing said one or more receivers at said mobile device independently of application of at least a portion of said one or more assistance parameters applied in said first process to obtain said first position fix; and

executing one or more user applications that rely on an availability of said second position fix.

2. The method of claim 1, wherein:

said initial position is obtained from said one or more assistance parameters.

3. The method of claim 1, wherein:

said initial position is based, at least in part, on a base station ID acquired at said mobile device.

4. The method of claim 1, wherein:

said obtaining said first position fix further comprises obtaining said first position fix using ephemeris and/or almanac information.

5. The method of claim 1, wherein:

said first process to obtain said first position fix comprises obtaining said first position fix based, at least in part, on said initial position of said second position mobile device; and

said second process to obtain fix comprises initiating a full sky scan to acquire said one or more second signals from said one or more satellite transmitters of said satellite positioning system.

6. The method of claim 1, further comprising:

determining that an outlier likelihood is greater than a second threshold.

7. The method of claim 6, wherein said computed reliability is based, at least in part, on a number of satellite signals acquired at said mobile device from different satellite transmitters of a satellite positioning system.

8. A mobile device comprising:

a satellite positioning system (SPS) receiver to acquire SPS signals;

a processor configured to;

start a first process to obtain a first position fix comprising an estimated location of said mobile device based, at least in part, on one or more first SPS signals acquired at said SPS receiver and an application of one or more assistance parameters;

detect an erroneous condition in a computation of said estimated location of said mobile device based, at least in part, on a comparison of said estimated location with an initial position of said mobile device, and based, at least in part, on a computed reliability of said first position fix;

responsive to detecting said erroneous condition, start a second process to obtain a second position fix based, at least in part, on one or more second satellite signals acquired from one or more satellite transmitters of said satellite positioning system at said SPS receiver independently of application of at least a portion of said one or more assistance parameters applied in said first process to obtain said first position fix; and

execute one or more user applications that rely on an availability of said second position fix.

9. The mobile device of claim 8, wherein:

said initial position is obtained from said one or more assistance parameters.

10. The mobile device of claim 8, wherein:

said initial position is based, at least in part, on a base station ID acquired at said mobile device.

11. The mobile device of claim 8, wherein:

said obtaining said first position fix further comprises obtaining said first position fix using ephemeris and/or almanac information for said SPS.

12. The mobile device of claim 8, wherein:

said first process to obtain said first position fix is comprises obtaining said first position fix based, at least in part, on said initial position of said mobile device; and

said second process to obtain said second position fix comprises initiating a full sky scan to acquire one or more second signals from said one or more satellite transmitters of said SPS.

13. An apparatus comprising:

a non-transitory medium having instructions stored thereon executable by a computing system to;

start a first process to obtain a first position fix comprising an estimated location of a mobile device based, at least in part, on signals acquired from one or more satellite transmitters of a satellite positioning system utilizing one or more receivers at said mobile device, said first process comprising application of one or more assistance parameters;

detect an erroneous condition in a computation of said estimated location of said mobile device based, at least in part, on a comparison of said estimated location with an initial position of said mobile device;

in response to said detection of said erroneous condition, and based, at least in part, on a computed reliability of said first position fix, start a second process at said mobile device to obtain a second position fix based, at least in part, on one or more second satellite signals acquired from one or more satellite transmitters of said satellite positioning system utilizing said one or more receivers at said mobile device independently of application of at least a portion of said one or more assistance parameters applied in said first process to obtain said first position fix; and

execute one or more user applications that rely on an availability of said second position fix.

14. The apparatus of claim 13, wherein said initial position is obtained from said one or more assistance parameters.

15. The apparatus of claim 13, wherein said initial position is based, at least in part, on a base station ID acquired at said mobile device.

16. The apparatus of claim 13, wherein:

said obtaining said first position fix further comprises obtaining said first position fix using ephemeris and/or almanac information.

17. The apparatus of claim 13, wherein:

said first process to obtain said first position fix comprises obtaining said first position fix based, at least in part, on said initial position of said mobile device; and

said second process to obtain said second position fix comprises initiating a full sky scan to acquire said one or more second signals from said one or more satellite transmitters of said satellite positioning system.

18. An apparatus comprising:

means for starting a first process to obtain a first position fix comprising an estimated location of a mobile device based, at least in part, on signals acquired from one or more satellite transmitters of a satellite positioning system utilizing one or more receivers at said mobile device, said first process comprising application of one or more assistance parameters;

means for detecting an erroneous condition in a computation of said estimated location of said mobile device based, at least in part, on a comparison of said estimated location with an initial position of said mobile device;

means for starting a second process at said mobile device to obtain a second position fix based, at least in part, on one or more second satellite signals acquired from one or more satellite transmitters of said satellite positioning system utilizing said one or more receivers at said mobile device independently of application of at least a portion of said one or more assistance parameters applied in said first process to obtain said first position fix, said second process to be started in response to said detection of said erroneous condition and based, at least in part, on a computed reliability of said first position fix; and

means for executing one or more user applications that rely on an availability of the second position fix.

19. The apparatus of claim 18, wherein:

said initial position is obtained from said one or more assistance parameters.

20. The apparatus of claim 18, wherein:

said initial position is based, at least in part, on a base station ID acquired at said mobile device.

21. The apparatus of claim 18, wherein:

said means for starting said first process further comprises;

means for obtaining said first position fix using ephemeris and/or almanac information.

22. The apparatus of claim 18, wherein:

said means for starting said first process to obtain said first position fix comprises means for obtaining said first position fix based, at least in part, on said initial position of said mobile device; and

said means for starting said second process to obtain said second position fix further comprises;

means for initiating a full sky scan to acquire said one or more second signals from said one or more satellite transmitters of said satellite positioning system.

23. A processor implemented method comprising:

starting a first process to obtain, from positioning assistance parameters, a first position fix comprising a time reference at a mobile device based, at least in part, on one or more first satellite signals acquired from one or more satellite transmitters of a satellite positioning system utilizing one or more receivers at said mobile device, said first process comprising application of one or more assistance parameters;

detecting an erroneous condition in a computation of said time reference at said mobile device based, at least in part, on a comparison of a time observed from acquisition of one or more positioning signals and said time reference obtained from said positioning assistance parameters;

in response to said detection of said erroneous condition, and based, at least in part, on a computed reliability of said first position fix, starting a second process at said mobile device to obtain a second position fix based, at least in part, on one or more second satellite signals acquired from one or more satellite transmitters of said satellite positioning system utilizing said one or more receivers at said mobile device independently of application of at least a portion of said one or more assistance parameters applied in said first process to obtain said first position fix; and

executing one or more user applications that rely on an availability of the second position fix.

24. A processor implemented method comprising:

starting a first process to obtain, from positioning assistance parameters, a first position fix comprising a location estimate of a mobile device based, at least in part, on one or more first satellite signals acquired from one or more satellite transmitters of a satellite positioning system utilizing one or more receivers at said mobile device, said first process comprising application of one or more assistance parameters;

detecting an erroneous condition responsive to an evaluation of a consistency of parameters observed from acquisition of from said one or more satellite transmitters of said satellite positioning system and an initial position obtained from said positioning assistance parameters;

in response to said detection of said erroneous condition, and based, at least in part, on a computed reliability of said first position fix, starting a second process at said mobile device to obtain a second position fix based, at least in part, on one or more second satellite signals acquired from one or more satellite transmitters of said satellite positioning system utilizing said one or more receivers at said mobile device independently of application of at least a portion of said one or more assistance parameters applied in said first process to obtain said first position fix; and

executing one or more user applications that rely on an availability of the second position fix.

25. A processor implemented method comprising:

starting a first process to obtain a first plurality of position fixes comprising a plurality of estimated locations of a mobile device based, at least in part, on one or more first satellite signals acquired from one or more satellite transmitters of a satellite positioning system utilizing one or more receivers at said mobile device, said first process comprising application of one or more assistance parameters;

detecting an erroneous condition responsive to an evaluation of a consistency of a speed of said mobile device based, at least in part, on said first plurality of position fixes and Doppler indications obtained from positioning assistance parameters;

in response to said detection of said erroneous condition, and based, at least in part, on a computed reliability of said first plurality of position fixes, starting a second process at said mobile device to obtain a second plurality of position fixes based, at least in part, on one or more second satellite signals acquired from one or more satellite transmitters of said satellite positioning system utilizing said one or more receivers at said mobile device independently of application of at least a portion of said one or more assistance parameters applied in said first process to obtain said first plurality of position fixes; and

executing one or more user applications that rely on an availability of said second plurality of position fixes.