Estimating the Location of a Wireless Terminal Based on the Traits of the Multipath Components of a Signal

• US 20060240845A1
• Filed: 05/22/2006
• Published: 10/26/2006
• Est. Priority Date: 09/22/1998
• Status: Active Grant

• Current Assignee: Polaris Wireless Incorporated
• Original Assignee: Polaris Wireless Incorporated
• Inventors: Gordon, Scot Douglas, Spain, David Stevenson Jr., Feuerstein, Martin
• Granted Patent: US 7,899,467 B2
• Time in Patent Office: Days
• US Class Current: 455/456.100
• CPC Class Codes: G01S 19/22 Multipath-related issues
• CPC Class Codes: G01S 19/25 involving aiding data received from a cooperating element, e.g. assisted GPS
• CPC Class Codes: G01S 19/42 Determining position
• CPC Class Codes: G01S 5/02521 using a radio-map
• CPC Class Codes: G01S 5/0273 using multipath or indirect path propagation signals in position determination
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A technique for estimating the location of a wireless terminal at an unknown location in a geographic region is disclosed. The technique is based on the recognition that there are traits of electromagnetic signals that are dependent on topography, the receiver, the location of the transmitter, and other factors. For example, if a particular radio station is known to be received strongly at a first location and weakly at a second location, and a given wireless terminal at an unknown location is receiving the radio station weakly, it is more likely that the wireless terminal is at the second location than at the first location.

Claims

1. A method comprising estimating the location of a wireless terminal based on a measured temporal difference of a pair of multipath components of a signal as processed by said wireless terminal.

2. The method of claim 1 wherein said wireless terminal receives said signal and wherein said measured temporal difference is measured at said wireless terminal.

3. The method of claim 1 wherein said wireless terminal transmits said signal and wherein said measured temporal difference is measured at a base station.

4. The method of claim 1 wherein estimating the location of said wireless terminal comprises comparing said measured temporal difference to:

(i) a first expected temporal difference of said pair of multipath components of said signal when said wireless terminal is at a first location, and

(ii) a second expected temporal difference of said pair of multipath components of said signal when said wireless terminal is at a second location.

30. The method of claim 1 wherein said wireless terminal receives said signal and wherein said measured delay spread is measured at said wireless terminal.

31. The method of claim 1 wherein said wireless terminal transmits said signal and wherein said measured delay spread is measured at a base station.

32. The method of claim 1 wherein estimating the location of said wireless terminal comprises comparing said delay spread difference to:

(i) a first expected delay spread of said signal when said wireless terminal is at a first location, and

(ii) a second expected delay spread of said signal when said wireless terminal is at a second location.

5. A method comprising:

(1) receiving (i) a first measured temporal difference for a first pair of multipath components of a first signal that is processed by a wireless terminal and (ii) a second measured temporal difference for a second pair of multipath components of a second signal that is processed by said wireless terminal; and

(2) estimating the location of said wireless terminal based on said first measured temporal difference and said second measured temporal difference.

6. The method of claim 5 wherein said wireless terminal receives said first signal and said second signal;

and

wherein said first measured temporal difference and said second measured temporal difference are measured at said wireless terminal.

7. The method of claim 5 wherein said wireless terminal transmits said first signal and said second signal;

and

wherein said first measured temporal difference is measured at a first base station and said second measured temporal difference is measured at a second base station.

8. The method of claim 5 wherein said wireless terminal receives said first signal and transmits said second signal;

and

wherein said first measured temporal difference is measured at said wireless terminal and said second measured temporal difference is measured at a base station.

9. The method of claim 5 wherein (2) estimating the location of said wireless terminal comprises:

(2.1) comparing said first measured temporal difference to;

(i) a first expected temporal difference of said first pair of multipath components of said first signal when said wireless terminal is at a first location, and

(ii) a second expected temporal difference of said first pair of multipath components of said first signal when said wireless terminal is at a second location; and

(2.2) comparing said second measured temporal difference to;

(i) a first expected temporal difference of said second pair of multipath components of said second signal when said wireless terminal is at said first location, and

(ii) a second expected temporal difference of said second pair of multipath components of said second signal when said wireless terminal is at said second location.

10. A method comprising:

(1) receiving (i) a first measured temporal difference for a first pair of multipath components of a first signal that is processed by a wireless terminal at a first time T₁ and (ii) a second measured temporal difference for said first pair of multipath components of said first signal at a second time T₂, wherein said first time does not equal said second time; and

(2) estimating the location of said wireless terminal at said second time based on (i) said first measured temporal difference, (ii) said second measured temporal difference, and (iii) an estimate of the probability that said wireless terminal in said location at time T will still be in said location at time T+Δ

t.

11. The method of claim 10 wherein said wireless terminal receives said first signal and said second signal;

and

wherein said first measured temporal difference and said second measured temporal difference are measured at said wireless terminal.

12. The method of claim 10 wherein said wireless terminal transmits said first signal and said second signal;

and

wherein said first measured temporal difference is measured at a first base station and said second measured temporal difference is measured at a second base station.

13. The method of claim 10 wherein said wireless terminal receives said first signal and transmits said second signal;

and

wherein said first measured temporal difference is measured at said wireless terminal and said second measured temporal difference is measured at a base station.

14. The method of claim 10 wherein (2) estimating the location of said wireless terminal comprises:

(2.1) comparing said first measured temporal difference to;

(i) a first expected temporal difference of said first pair of multipath components of said first signal when said wireless terminal is at a first location at said first time T₁, and

(ii) a second expected temporal difference of said first pair of multipath components of said first signal when said wireless terminal is at a second location at said first time T₁; and

(2.2) comparing said second measured temporal difference to;

(i) a first expected temporal difference of said second pair of multipath components of said second signal when said wireless terminal is at said first location at said first time T₂, and

(ii) a second expected temporal difference of said second pair of multipath components of said second signal when said wireless terminal is at said second location at said first time T₂.

25. The method of claim 10 wherein said wireless terminal receives said first signal and said second signal;

and

wherein said first pair of measured temporal differences and said second pair of measured temporal differences are measured at said wireless terminal.

26. The method of claim 10 wherein said wireless terminal transmits said first signal and said second signal;

and

wherein said first pair of measured temporal differences is measured at a first base station and said second pair of measured temporal differences is measured at a second base station.

27. The method of claim 10 wherein said wireless terminal receives said first signal and transmits said second signal;

and

wherein said first pair of measured temporal differences is measured at said wireless terminal and said second pair of measured temporal differences is measured at a base station.

28. The method of claim 10 wherein (2) estimating the location of said wireless terminal comprises:

(2.1) comparing said first pair of measured temporal differences to;

(i) a first expected temporal difference of said first triplet of multipath components of said first signal when said wireless terminal is at a first location at said first time T₁, and

(ii) a second expected temporal difference of said first triplet of multipath components of said first signal when said wireless terminal is at a second location at said first time T₁; and

(2.2) comparing said second pair of measured temporal differences to;

(i) a first expected temporal difference of said second triplet of multipath components of said second signal when said wireless terminal is at said first location at said first time T₂, and

(ii) a second expected temporal difference of said second triplet of multipath components of said second signal when said wireless terminal is at said second location at said first time T₂.

15. A method comprising estimating the location of a wireless terminal based on a pair of measured temporal differences of a triplet of multipath components of a signal as processed by said wireless terminal.

16. The method of claim 15 wherein said wireless terminal receives said signal and wherein said pair of measured temporal differences is measured at said wireless terminal.

17. The method of claim 15 wherein said wireless terminal transmits said signal and wherein said pair of measured temporal differences is measured at a base station.

18. The method of claim 15 wherein estimating the location of said wireless terminal comprises comparing said measured temporal difference to:

(i) a first pair of expected temporal differences of said triplet of multipath components of said signal when said wireless terminal is at a first location, and

(ii) a second pair of expected temporal differences of said triplet of multipath components of said signal when said wireless terminal is at a second location.

19. A method comprising:

(1) receiving (i) a first pair of measured temporal differences for a first triplet of multipath components of a first signal that is processed by a wireless terminal and (ii) a second pair of measured temporal differences for a second triplet of multipath components of a second signal that is processed by said wireless terminal; and

(2) estimating the location of said wireless terminal based on said first pair of measured temporal differences and said second pair of measured temporal differences.

20. The method of claim 19 wherein said wireless terminal receives said first signal and said second signal;

and

wherein said first pair of measured temporal differences and said second pair of measured temporal differences are measured at said wireless terminal.

21. The method of claim 19 wherein said wireless terminal transmits said first signal and said second signal;

and

wherein said first pair of measured temporal differences is measured at a first base station and said second pair of measured temporal differences is measured at a second base station.

22. The method of claim 19 wherein said wireless terminal receives said first signal and transmits said second signal;

and

wherein said first pair of measured temporal differences is measured at said wireless terminal and said pair of second measured temporal differences is measured at a base station.

23. The method of claim 19 wherein (2) estimating the location of said wireless terminal comprises:

(2.1) comparing said first pair of measured temporal differences to;

(i) a first pair of expected temporal differences of said first triplet of multipath components of said first signal when said wireless terminal is at a first location, and

(ii) a second pair of expected temporal differences of said first triplet of multipath components of said first signal when said wireless terminal is at a second location; and

(2.2) comparing said second pair of measured temporal differences to;

(i) a first pair of expected temporal differences of said second triplet of multipath components of said second signal when said wireless terminal is at said first location, and

(ii) a second pair of expected temporal differences of said second triplet of multipath components of said second signal when said wireless terminal is at said second location.

24. A method comprising:

(1) receiving (i) a first pair of measured temporal differences for a first triplet of multipath components of a first signal that is processed by a wireless terminal at a first time T₁ and (ii) a second pair of measured temporal differences for said first triplet of multipath components of said first signal at a second time T₂, wherein said first time does not equal said second time; and

(2) estimating the location of said wireless terminal at said second time based on (i) said first pair of measured temporal differences, (ii) said second pair of measured temporal differences, and (iii) an estimate of the probability that said wireless terminal in said location at time T will still be in said location at time T+Δ

t.

29. A method comprising estimating the location of a wireless terminal based on a measured delay spread of a signal as processed by said wireless terminal.

33. A method comprising:

(1) receiving (i) a first measured delay spread of a first signal that is processed by a wireless terminal and (ii) a second measured delay spread of a second signal that is processed by said wireless terminal; and

(2) estimating the location of said wireless terminal based on said first measured delay spread and said second measured delay spread.

34. The method of claim 33 wherein said wireless terminal receives said first signal and said second signal;

and

wherein said first measured delay spread and said second measured delay spread are measured at said wireless terminal.

35. The method of claim 33 wherein said wireless terminal transmits said first signal and said second signal;

and

wherein said first measured delay spread is measured at a first base station and said second measured delay spread is measured at a second base station.

36. The method of claim 33 wherein said wireless terminal receives said first signal and transmits said second signal;

and

wherein said first measured delay spread is measured at said wireless terminal and said second measured delay spread is measured at a base station.

37. The method of claim 33 wherein (2) estimating the location of said wireless terminal comprises:

(2.1) comparing said first measured delay spread to;

(i) a first expected delay spread of said first signal when said wireless terminal is at a first location, and

(ii) a second expected delay spread of said first signal when said wireless terminal is at a second location; and

(2.2) comparing said second measured delay spread to;

(i) a first expected delay spread of said second signal when said wireless terminal is at said first location, and

(ii) a second expected delay spread of said second signal when said wireless terminal is at said second location.

38. A method comprising:

(1) receiving (i) a first measured delay spread of a first signal that is processed by a wireless terminal at a first time T₁ and (ii) a second measured delay spread of said first signal at a second time T₂, wherein said first time does not equal said second time; and

(2) estimating the location of said wireless terminal at said second time based on (i) said first measured delay spread, (ii) said second measured delay spread, and (iii) an estimate of the probability that said wireless terminal in said location at time T will still be in said location at time T+Δ

t.

39. The method of claim 38 wherein said wireless terminal receives said first signal and said second signal;

and

wherein said first measured delay spread and said second measured delay spread are measured at said wireless terminal.

40. The method of claim 38 wherein said wireless terminal transmits said first signal and said second signal;

and

wherein said first measured delay spread is measured at a first base station and said second measured delay spread is measured at a second base station.

41. The method of claim 38 wherein said wireless terminal receives said first signal and transmits said second signal;

and

wherein said first measured delay spread is measured at said wireless terminal and said second measured delay spread is measured at a base station.

42. The method of claim 38 wherein (2) estimating the location of said wireless terminal comprises:

(2.1) comparing said first measured delay spread to;

(i) a first expected delay spread of said first signal when said wireless terminal is at a first location at said first time T₁, and

(ii) a second expected delay spread of said first signal when said wireless terminal is at a second location at said first time T₁; and

(2.2) comparing said second measured delay spread to;

(i) a first expected delay spread of said second signal when said wireless terminal is at said first location at said first time T₂, and

(ii) a second expected delay spread of said second signal when said wireless terminal is at said second location at said first time T₂.