METHOD AND APPARATUS FOR ESTIMATING SATELLITE POSITIONING RELIABILITY

• US 20120178470A1
• Filed: 12/20/2011
• Published: 07/12/2012
• Est. Priority Date: 12/22/2010
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Riley, Wyatt T., Morrison, William J., Luo, Ning
• Granted Patent: US 9,031,572 B2
• Time in Patent Office: Days
• US Class Current: 455/456.1
• CPC Class Codes: G01S 19/20 Integrity monitoring, fault detection or fault isolation of space segment
• CPC Class Codes: G01S 19/42 Determining position
• CPC Class Codes: G01S 19/46 the supplementary measurement being of a radio-wave signal type

Abstract

A position fix of a mobile device is computed based, at least in part, on a plurality of data items. A metric that is indicative of a reliability of the position fix may be generated based, at least in part, on a number of independent ones of the data items and/or an indication of reliability of at least one of the data items. In at least one implementation, the plurality of data items may include SPS satellite signals and/or pseudoranges and an externally obtained position.

Claims

1. A machine implemented method for determining a metric for a position fix of a mobile device, comprising:

obtaining a plurality of data items at the mobile device;

computing the position fix of the mobile device based, at least in part, on the plurality of data items; and

determining a metric indicative of a reliability of the computed position fix based, at least in part, on a number of independent ones of the data items and/or an indication of reliability of at least one of the data items.

2. The method of claim 1, further comprising:

determining a number of degrees-of-freedom provided by the plurality of data items;

wherein determining the metric indicative of the reliability of the computed position fix includes determining the metric based, at least in part, on the determined number of degrees-of-freedom.

3. The method of claim 2, wherein:

determining the number of degrees-of-freedom provided by the plurality of data items includes determining a difference between a number of equations and a number of unknowns of a position solution based, at least in part, on the plurality of data items.

4. The method of claim 3, wherein:

at least one of the data items within the plurality of data items comprises an externally obtained position; and

determining the number of degrees-of-freedom provided by the plurality of data items further includes adding a fixed increment to the difference based, at least in part, on the externally obtained position.

5. The method of claim 1, wherein:

at least one of the data items within the plurality of data items comprises an externally obtained position;

wherein determining the metric further comprises determining the metric based, at least in part, on an indication of reliability of the externally obtained position.

6. The method of claim 1, wherein:

the position fix comprises an estimated location of the mobile device and a measurement of accuracy of the estimated location.

7. An apparatus comprising:

a position fix computation unit to compute a position fix of the apparatus based, at least in part, on a plurality of data items; and

a reliability determination unit to determine a metric indicative of a reliability of the computed position fix based, at least in part, on a number of independent ones of the data items and/or an indication of reliability of at least one of the data items.

8. The apparatus of claim 7, wherein:

the reliability determination unit is to;

determine a number of degrees-of-freedom provided by the plurality of data items; and

determine the metric indicative of the reliability of the position fix based, at least in part, on the number of degrees-of-freedom.

9. The apparatus of claim 8, wherein:

the reliability determination unit is to determine the number of degrees-of-freedom based, at least in part, on a difference between a number of equations and a number of unknowns of a position solution.

10. The apparatus of claim 9, wherein:

at least one of the data items within the plurality of data items comprises an externally obtained position; and

the reliability determination unit is to determine the number of degrees-of-freedom by adding a fixed increment to the difference based, at least in part, on the externally obtained position.

11. The apparatus of claim 9, wherein:

at least one of the data items within the plurality of data items comprises an externally obtained position; and

the reliability determination unit is to determine the metric based, at least in part, on an indication of reliability of the externally obtained position.

12. The apparatus of claim 7, wherein:

the position fix comprises an estimated location of the mobile device and a measurement of uncertainty of the estimated location.

13. An article comprising:

a non-transitory storage medium having machine-readable instructions stored thereon which are executable by a special purpose computing apparatus to;

obtain a plurality of data items at a mobile device;

compute a position fix of the mobile device based, at least in part, on the plurality of data items; and

determine a metric indicative of a reliability of the computed position fix based, at least in part, on a number of independent ones of the data items and/or an indication of reliability of at least one of the data items.

14. The article of claim 13, wherein the non-transitory storage medium has further machine-readable instructions stored thereon which are executable by a special purpose computing apparatus to:

determine a number of degrees-of-freedom provided by the plurality of data items;

wherein determining the metric indicative of the reliability of the position fix includes determining the metric based, at least in part, on the determined number of degrees-of-freedom.

15. The article of claim 14, wherein the machine-readable instructions to determine the number of degrees-of-freedom include instructions to determine a difference between a number of equations and a number of unknowns of a position solution based, at least in part, on the plurality of data items.

16. The article of claim 15, wherein:

at least one of the data items within the plurality of data items comprises an externally obtained position; and

the machine-readable instructions to determine the number of degrees-of-freedom include instructions to add a fixed increment to the difference based, at least in part, on the externally obtained position.

17. The article of claim 13, wherein:

at least one of the data items within the plurality of data items comprises an externally obtained position;

wherein the machine-readable instructions to determine the metric further comprise instructions to determine the metric based, at least in part, on an indication of reliability of the externally obtained position.

18. An apparatus for determining a metric for a position fix of a mobile device, comprising:

means for obtaining a plurality of data items at a mobile device;

means for computing the position fix of the mobile device based, at least in part, on the plurality of data items; and

means for determining a metric indicative of a reliability of the computed position fix based, at least in part, on a number of independent ones of the data items and/or an indication of reliability of at least one of the data items.

19. The apparatus of claim 18, further comprising:

means for determining a number of degrees-of-freedom provided by the plurality of data items;

wherein the means for determining the metric indicative of the reliability of the position fix includes means for determining the metric based, at least in part, on the number of degrees-of-freedom.

20. The apparatus of claim 19, wherein:

the means for determining the number of degrees-of-freedom provided by the plurality of data items includes means for determining a difference between a number of equations and a number of unknowns of a position solution based, at least in part, on the plurality of data items.

21. The apparatus of claim 20, wherein:

at least one of the data items within the plurality of data items comprises an externally obtained position; and

the means for determining the number of degrees-of-freedom provided by the plurality of data items further includes means for adding a fixed increment to the difference based, at least in part, on the externally obtained position.

22. The apparatus of claim 18, wherein:

at least one of the data items within the plurality of data items comprises an externally obtained position; and

the means for determining the metric further comprises means for determining the metric based, at least in part, on an indication of reliability of the externally obtained position.