Method for ambiguity resolution in location determination

• US 20060106573A1
• Filed: 01/12/2005
• Published: 05/18/2006
• Est. Priority Date: 11/17/2004
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Seibert, Cristina
• Granted Patent: US 7,881,905 B2
• Time in Patent Office: Days
• US Class Current: 702/181
• CPC Class Codes: G01S 5/02527 Detecting or resolving anomalies in the radio frequency fingerprints of the radio-map
• CPC Class Codes: G01S 5/0258 by combining or switching between measurements derived from different systems
• CPC Class Codes: G01S 5/0268 by deriving positions from different combinations of signals or of estimated positions in a single positioning system
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details

Abstract

A method using various heuristics techniques for resolving ambiguity in location determination in environments with or without noise. A final location determination solution may be determined from a set of ambiguous location determination solutions by using clock temporal bias value, by using consistency information of ranging signal order such as the time of arrival and/or the received power level of the ranging signals, by using the distances to the sources, and/or by using other discriminator functions to select the final location determination solution from a plurality of ambiguous location determination solutions. The main advantage of the heuristic approaches is that redundant measurements are not required for location determination solution disambiguation.

Claims

1. A method for resolving ambiguity in location determination with N ambiguous location determination solutions using clock temporal bias value comprising:

generating a probability distribution function (PDF) model for clock temporal bias;

obtaining N clock temporal bias values for the N ambiguous location determination solutions;

inserting each of the N clock temporal bias values into the PDF model;

evaluating the PDF model to get N PDF values;

setting N goodness metrics to the N PDF values;

comparing the N goodness metrics;

defining a maximum goodness metric as the largest of the N goodness metrics; and

selecting a final location determination solution having the maximum goodness metric.

2. The method of claim 1 wherein the PDF model is parameterized by its mean and standard deviation.

3. The method of claim 1 wherein the PDF model is parameterized by a finite set of statistical parameters.

4. The method of claim 1 wherein N equals 2.

5. A method for resolving ambiguity in location determination with a plurality of ambiguous location determination solutions using the order of receipt (a.k.a. time of arrival) of a plurality of ranging signals comprising:

ranking the plurality of ranging signals based on the order of actual time of arrival (TOA) from earliest to latest;

ranking the plurality of ranging signals based on an expected order of time of arrival corresponding to each of the plurality of ambiguous location determination solutions; and

comparing the ranking of the ranging signals based on the order of the actual time of arrival (TOA) and based on the expected order of time of arrival corresponding to each of the plurality of ambiguous location determination solutions.

6. The method of claim 5 further comprising the step of selecting a final location determination solution as having the closest match in ordering.

7. The method of claim 5 further comprising the step of selecting a final location determination solution as having a combination of the plurality of ambiguous location determination solutions with the closest match in ordering.

8. A method for resolving ambiguity in location determination with a plurality of ambiguous location determination solutions using the order of received power levels of a plurality of ranging signals comprising:

ranking the plurality of ranging signals based on the order of received power levels from strongest to weakest;

ranking the plurality of ranging signals based on an expected order of received power levels corresponding to each of the plurality of ambiguous location determination solutions; and

comparing the ranking of the ranging signals based on the order of received power levels and based on the expected order of received power levels corresponding to each of the plurality of ambiguous location determination solutions.

9. The method of claim 8 further comprising the step of selecting a final location determination solution as having the closest match in ordering.

10. The method of claim 8 further comprising the step of selecting a final location determination solution as having a combination of the plurality of ambiguous location determination solutions with the closest match in ordering.

11. A method for resolving ambiguity in location determination with a plurality of ambiguous location determination solutions comprising:

deriving a plurality of distances D1 corresponding to each of the plurality of ambiguous location determination solutions for each of M sources;

obtaining a plurality of original distances D2;

comparing each of the plurality of distances D1 with each of its corresponding plurality of original distances D2 and computing a plurality of error measurements; and

selecting a final location determination solution as having the lowest value of the plurality of error measurements.

12. The method of claim 11 wherein the plurality of error measurements are the root-mean-square values of distances D1 minus original distances D2.

13. The method of claim 11 wherein the plurality of error measurements are the root-sum-square values of distances D1 minus original distances D2.

14. The method of claim 11 wherein the plurality of error measurements are the root-mean-square values of distances D1 minus original distances D2 normalized by the size of vector D1.

15. The method of claim 11 wherein the plurality of error measurements are the root-mean-square values of distances D1 minus original distances D2 normalized by the size of vector D2.

16. A method for resolving ambiguity in location determination in a noisy environment comprising:

selecting L noise levels iteratively within a range [A, B] with an increment I for a first of Q ranging signals;

repeating the selecting step Q minus 1 times for each of the rest of the Q minus 1 ranging signals to produce a plurality of L noise levels;

creating a plurality of ambiguous location determination solutions for each of the plurality of L noise levels based on a geometric technique;

selecting the final location determination solution from the plurality of ambiguous location determination solutions based on a discriminator function.

17. The method of claim 16 wherein Q equals 2.

18. The method of claim 16 wherein the geometric technique is trilateration

19. The method of claim 16 wherein the discriminator function uses a combination of goodness metrics such as power ranking, distance values, clock temporal bias constraints and order of receipt of the ranging signals.

20. The method of claim 16 wherein the discriminator function uses at least two combinations of goodness metrics selected from power ranking, distance values, clock temporal bias constraints and order of receipt of the ranging signals.

21. The method of claim 16 wherein the discriminator function uses one goodness metrics selected from power ranking, distance values, clock temporal bias constraints and order of receipt of the ranging signals.

22. Computer readable media embodying a program of instructions executable by a computer program to perform a method for resolving ambiguity in location determination with N ambiguous location determination solutions using clock temporal bias value, the method comprising:

generating a probability distribution function (PDF) model for clock temporal bias;

obtaining N clock temporal bias values for the N ambiguous location determination solutions;

inserting each of the N clock temporal bias values into the PDF model;

evaluating the PDF model to get N PDF values;

setting N goodness metrics to the N PDF values;

comparing the N goodness metrics;

defining a maximum goodness metric as the largest of the N goodness metrics; and

selecting a final location determination solution having the maximum goodness metric.

23. Computer readable media embodying a program of instructions executable by a computer program to perform a method for resolving ambiguity in location determination with a plurality of ambiguous location determination solutions using the order of receipt (a.k.a. time of arrival) of a plurality of ranging signals, the method comprising:

ranking the plurality of ranging signals based on the order of actual time of arrival (TOA) from earliest to latest;

ranking the plurality of ranging signals based on an expected order of time of arrival corresponding to each of the plurality of ambiguous location determination solutions; and

comparing the ranking of the ranging signals based on the order of the actual time of arrival (TOA) and based on the expected order of time of arrival corresponding to each of the plurality of ambiguous location determination solutions.

24. Computer readable media embodying a program of instructions executable by a computer program to perform a method for resolving ambiguity in location determination with a plurality of ambiguous location determination solutions using the order of received power levels of a plurality of ranging signals, the method comprising:

ranking the plurality of ranging signals based on the order of received power levels from strongest to weakest;

ranking the plurality of ranging signals based on an expected order of received power levels corresponding to each of the plurality of ambiguous location determination solutions; and

comparing the ranking of the ranging signals based on the order of received power levels and based on the expected order of received power levels corresponding to each of the plurality of ambiguous location determination solutions.

25. Computer readable media embodying a program of instructions executable by a computer program to perform a method for resolving ambiguity in location determination with a plurality of ambiguous location determination solutions, the method comprising:

deriving a plurality of distances D1 corresponding to each of the plurality of ambiguous location determination solutions for each of M sources;

obtaining a plurality of original distances D2;

comparing each of the plurality of distances D1 with each of its corresponding plurality of original distances D2 and computing a plurality of error measurements; and

selecting a final location determination solution as having the lowest value of the plurality of error measurements.

26. Computer readable media embodying a program of instructions executable by a computer program to perform a method for resolving ambiguity in location determination in a noisy environment, the method comprising:

selecting L noise levels iteratively within a range [A, B] with an increment I for a first of Q ranging signals;

repeating the selecting step Q minus 1 times for each of the rest of the Q minus 1 ranging signals to produce a plurality of L noise levels;

creating a plurality of ambiguous location determination solutions for each of the plurality of L noise levels based on a geometric technique;

selecting the final location determination solution from the plurality of ambiguous location determination solutions based on a discriminator function.