Detecting multipath and determining positioning measurement uncertainty

• US 9,467,803 B2
• Filed: 09/27/2012
• Issued: 10/11/2016
• Est. Priority Date: 09/27/2012
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Siomina, Iana, Zhang, Yang
• Primary Examiner(s): MITCHELL, NATHAN A
• Application Number:
  US13/704,130
• Publication Number:
  US 20140087754A1
• Time in Patent Office: 1,475 Days
• Field of Search: 4554561-4566
• US Class Current: 1/1
• CPC Class Codes: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• CPC Class Codes: G01S 5/0218 Multipath in signal reception
• CPC Class Codes: G01S 5/0244 Accuracy or reliability of position solution or of measurements contributing thereto
• CPC Class Codes: H04W 4/02 Services making use of location information
• CPC Class Codes: H04W 4/029 Location-based management or tracking services

Abstract

Techniques are disclosed for determining measurement uncertainty of and/or multipath effects on positioning measurements, based on the residual deviations between timing measurements and high-accuracy location results. An example method begins with collecting (510) a plurality of timing measurements or ranging measurements, or both, each measurement corresponding to at least one anchor node antenna having a known location. A measurement deviation is determined (520) for each measurement by comparing the measurement to a corresponding reference location. The measurement deviations are used (530) to estimate measurement quality for one or more subsequent positioning measurements, and/or uncertainty associated with one or more subsequent positioning estimates, and/or an effect of multipath on subsequent positioning measurements or estimates. In some embodiments, a covariance matrix is calculated from the measurement deviations and is used to determine statistical information or multipath effects for measurements corresponding to a particular one of the anchor node antennas.

Claims

1. A method, in a first node in a wireless communications network, for use in positioning, the method comprising:

collecting, for each of a plurality of wireless devices, one or more timing measurements, each measurement corresponding to at least one anchor node antenna having a known location;

determining a measurement deviation for each measurement by comparing the measurement to an expected timing measurement corresponding to a reference location; and

using the measurement deviations for one or more of estimating measurement quality of one or more subsequent positioning measurements, estimating uncertainty associated with one or more subsequent positioning estimates, and estimating an effect of multipath on one or more subsequent positioning measurements or estimates.

2. The method of claim 1, wherein said collecting comprises receiving the measurements from one or more measuring nodes or network nodes, retrieving the measurements from a database, or reading the measurements from a computer-readable medium.

3. The method of claim 1, further comprising aggregating measurement deviations separately for each of two or more areas of interest.

4. The method of claim 1, wherein said using the measurement deviations comprises sending one or more of the measurement deviations to a second node for use by the second node for one or more of estimating measurement quality for one or more subsequent positioning measurements, estimating uncertainty associated with one or more subsequent positioning estimates, and estimating an effect of multipath on one or more subsequent positioning measurements or estimates.

5. The method of claim 1, wherein said using the measurement deviations comprises calculating a covariance matrix from the measurement deviations, such that each row and column in the covariance matrix corresponds to one of the anchor node antennas.

6. The method of claim 5, wherein said using the measurement deviations comprises sending the covariance matrix to a second node for use by the second node for one or more of estimating measurement quality for one or more subsequent positioning measurements, estimating uncertainty associated with one or more subsequent positioning estimates, and estimating an effect of multipath on one or more subsequent positioning measurements or estimates.

7. The method of claim 5, further comprising using all or a portion of the covariance matrix to determine statistical information or multipath effects for measurements corresponding to a particular one of the anchor node antennas.

8. The method of claim 7, wherein determining statistical information corresponding to a particular one of the anchor node antennas comprises calculating measurement variances associated with each diagonal element of the covariance matrix, based on an assumption that the measurement deviations are mean-zero distributed and further based on an assumption that the measurement variance associated with one of the diagonal elements of the covariance matrix is zero.

9. The method of claim 8, further comprising selecting the one of the diagonal elements based on determining that the one of the diagonal elements corresponds to an anchor node antenna having a line-of-sight to an area from which the measurements are collected.

10. The method of claim 5, further comprising calculating a positioning location based on the covariance matrix.

11. The method of claim 10, wherein said calculating of the positioning location is based on a nonlinear estimation algorithm selected from the following:

extended Kalman filtering;

unscented Kalman filtering;

particle filtering; and

Maximum Likelihood estimation.

12. The method of claim 1, further comprising determining an estimated measurement quality for a positioning measurement, based on the measurement deviations.

13. The method of claim 12, wherein determining the estimated measurement quality comprises using aggregated measurement deviations for an area of interest to determine measurement quality for a positioning measurement corresponding to the area of interest.

14. The method of claim 12, further comprising determining whether the measurement deviations include at least a threshold number of measurement deviations before using the measurement deviations to determine the estimated measurement quality.

15. The method of claim 12, wherein determining the estimated measurement quality comprises weighting one or more of the measurement deviations based on a measurement age, before aggregating the measurement deviations to determine the estimated measurement quality.

16. The method of claim 12, further comprising omitting the positioning measurement from a positioning calculation, based on a comparison of the estimated measurement quality to a threshold.

17. The method of claim 12, further comprising selecting a positioning method based on the estimated measurement quality.

18. The method of claim 12, further comprising configuring a measurement request based on the estimated measurement quality.

19. The method of claim 12, further comprising comparing the estimated measurement quality to a reported measurement quality received from a measuring node, to verify the reported measurement quality.

20. The method of claim 12, further comprising using the estimated measurement quality to weight the positioning measurement in a position calculation.

21. A method, in a second node in a wireless communications network, for using measurement quality information in positioning, the method comprising:

receiving measurement deviations, for each of a plurality of wireless devices, from a first node, wherein said measurement deviations correspond to a plurality of timing measurements, each measurement deviation corresponding to at least one anchor node antenna having a known location; and

using the received measurement deviations for one or more of estimating measurement quality of one or more subsequent positioning measurements, estimating uncertainty associated with one or more subsequent positioning estimates, and estimating an effect of multipath on one or more subsequent positioning measurements or estimates.

22. The method of claim 21, wherein the received measurement deviations are aggregated separately for each of two or more areas of interest.

23. The method of claim 21, wherein said using the measurement deviations comprises calculating a covariance matrix from the measurement deviations, such that each row and column in the covariance matrix corresponds to one of the anchor node antennas.

24. The method of claim 21, further comprising receiving a covariance matrix from the first node, wherein the covariance matrix corresponds to the measurement deviations and wherein each row and column in the covariance matrix corresponds to one of the anchor node antennas.

25. The method of claim 23, wherein said using the measurement deviations further comprises using all or a portion of the covariance matrix to determine statistical information or multipath effects for measurements corresponding to a particular one of the anchor node antennas.

26. The method of claim 25, wherein determining statistical information corresponding to a particular one of the anchor node antennas comprises calculating measurement variances associated with each diagonal element of the covariance matrix, based on an assumption that the measurement deviations are mean-zero distributed and further based on an assumption that the measurement variance associated with one of the diagonal elements of the covariance matrix is zero.

27. The method of claim 23, wherein said using the measurement deviations further comprises calculating a positioning location based on the covariance matrix.

28. The method of claim 21, wherein said using the measurement deviations comprises determining an estimated measurement quality for a positioning measurement, based on the measurement deviations.

29. The method of claim 28, wherein determining the estimated measurement quality comprises using measurement deviations for an area of interest to determine measurement quality for a positioning measurement corresponding to the area of interest.

30. The method of claim 28, further comprising omitting the positioning measurement from a positioning calculation, based on a comparison of the estimated measurement quality to a threshold.

31. The method of claim 28, wherein said using the measurement deviations further comprises selecting a positioning method based on the estimated measurement quality.

32. The method of claim 28, wherein said using the measurement deviations further comprises comparing the estimated measurement quality to a reported measurement quality received from a measuring node, to verify the reported measurement quality.

33. The method of claim 28, wherein said using the measurement deviations further comprises using the estimated measurement quality to weight the positioning measurement in a position calculation.

34. A node for use in a wireless communication system, the node comprising

a network interface circuit adapted for communication with one or more other nodes in the wireless communication system, and

a processing circuit, wherein the processing circuit is configured to:

collect, for each of a plurality of wireless devices, one or more timing measurements, each measurement corresponding to at least one anchor node antenna having a known location;

determine a measurement deviation for each measurement by comparing the measurement to an expected timing measurement corresponding to a reference location; and

use the measurement deviations for one or more of estimating measurement quality of one or more subsequent positioning measurements, estimating uncertainty associated with one or more subsequent positioning estimates, and estimating an effect of multipath on one or more subsequent positioning measurements or estimates.