SYSTEMS AND METHODS FOR TRANSPARENCY MAPPING USING MULTIPATH SIGNALS

• US 20090102711A1
• Filed: 09/17/2008
• Published: 04/23/2009
• Est. Priority Date: 01/19/2005
• Status: Active Grant

• Current Assignee: Charles Stark Draper Laboratory Incorporated
• Original Assignee: Charles Stark Draper Laboratory Incorporated
• Inventors: Soltz, J. Arnold, Elwell, John M. JR., Gustafson, Donald E.
• Granted Patent: US 8,279,119 B2
• Time in Patent Office: Days
• US Class Current: 342/357.520
• CPC Class Codes: G01S 5/02527 Detecting or resolving anomalies in the radio frequency fingerprints of the radio-map
• CPC Class Codes: G01S 5/0273 using multipath or indirect path propagation signals in position determination

Abstract

Systems and methods for mapping a structure detect wireless signals, including at least one multipath signal that has experienced at least one reflection against a portion of the structure prior to the detection. The wireless signals are analyzed to estimate reflection points for the multipath signal(s), and a map of at least the portion of the structure is generated based on the estimated reflection points.

Claims

1. A method for mapping a structure, the method comprising:

detecting a plurality of wireless signals that comprise at least one multipath signal that has experienced at least one reflection against a portion of a structure prior to the detection;

analyzing the plurality of wireless signals to estimate reflection points for the at least one multipath signal; and

generating a map of at least the portion of the structure based on the estimated reflection points.

2. The method according to claim 1, wherein the plurality of wireless signals are received from one or more sources and are detected with at least one receiver.

3. The method according to claim 2, wherein the one or more sources comprise one or more satellites moving in space.

4. The method according to claim 2, wherein the one or more sources comprise at least two transmitters at known terrestrial locations.

5. The method according to claim 2, further comprising:

causing the at least one receiver to move along a known trajectory within or near the structure.

6. The method according to claim 2, further comprising:

causing the at least one receiver to move along an unknown trajectory within or near the structure; and

tracking a location of the at least one receiver.

7. The method according to claim 6, wherein the tracking and the generating take place at substantially the same time and in recursive steps.

8. The method according to claim 1, wherein the analyzing further comprises:

processing a multipath signal with a Rake filter to correlate the multipath signal with a corresponding direct path signal;

determining a time delay between the multipath signal and the corresponding direct path signal; and

estimating one or more parameters associated with a multipath delay model.

9. The method of claim 1, wherein the plurality of wireless signals are transmitted from one or more sources selected from the group consisting of:

one or more mobile transmitters and one or more fixed terrestrial transmitters.

10. The method according to claim 1, further comprising:

assigning one of the plurality of wireless signals to a corresponding signal path.

11. The method according to claim 1, wherein the analyzing further comprises distinguishing the at least one multipath signal from a corresponding direct-path signal.

12. The method according to claim 1, wherein the analyzing further comprises associating the at least one multipath signal with a corresponding direct-path signal.

13. The method according to claim 1, wherein the generating comprises employing both direct-path signals and multipath signals in the plurality of wireless signals.

14. The method according to claim 1, wherein the analyzing further comprises:

iteratively estimating one or more multipath parameters associated with a multipath delay model.

15. The method according to claim 14, wherein the one or more multipath parameters for a multipath signal comprise an angle-of-arrival from a last reflection experienced by the multipath signal.

16. The method according to claim 1, further comprising:

distinguishing single-reflection multipath signals from multiple-reflection multipath signals.

17. The method according to claim 1, further comprising:

identifying one or more true reflection surfaces responsible for producing the at least one multipath signal based on a statistical inference.

18. The method according to claim 1, further comprising:

eliminating one or more erroneous mapping points that result from a proximity effect.

19. A system for mapping a structure, the system comprising:

a) at least one receiver for detecting a plurality of wireless signals originating from one or more sources, the plurality of wireless signals comprising at least one multipath signal that has experienced at least one reflection against a portion of a structure prior to the detection; and

b) a processor, associated with the at least one receiver, for;

i) analyzing the plurality of wireless signals to estimate reflection points for the at least one multipath signal; and

ii) generating a map of at least the portion of the structure based on the estimated reflection points.

20. The system according to claim 19, wherein the one or more sources comprise one or more satellites moving in space.

21. The system according to claim 19, wherein the one or more sources comprise at least two transmitters at known terrestrial locations.

22. The system according to claim 19, wherein the at least one receiver moves along a known trajectory within or near the structure.

23. The system according to claim 19, wherein the at least one receiver moves along an unknown trajectory within or near the structure, and the system being further configured to track a location of the at least one receiver.

24. The system according to claim 23, wherein the tracking of the location of the at least one receiver and the generating of the map take place at substantially the same time and in recursive steps.

25. The system according to claim 19, further comprising a Rake filter for processing a multipath signal in order to correlate the multipath signal with a corresponding direct path signal, and wherein the processor is further configured to i) determine a time delay between the multipath signal and the corresponding direct path signal and ii) to estimate one or more parameters associated with a multipath delay model.

26. The system of claim 19, wherein the one or more sources are selected from the group consisting of:

one or more mobile transmitters and one or more fixed terrestrial transmitters.

27. The system according to claim 19, wherein the at least one receiver is further configured to assign one of the plurality of wireless signals to a corresponding signal path.

28. The system according to claim 19, wherein the processor is further configured to distinguish the at least one multipath signal from a corresponding direct-path signal.

29. The system according to claim 19, wherein the processor is further configured to associate the at least one multipath signal with a corresponding direct-path signal.

30. The system according to claim 19, wherein the generating of the map is based on both direct-path signals and multipath signals in the plurality of wireless signals.

31. The system according to claim 19, wherein the processor is further configured to iteratively estimate one or more multipath parameters associated with a multipath delay model.

32. The system according to claim 31, wherein the one or more multipath parameters for a multipath signal comprise an angle-of-arrival from a last reflection experienced by the multipath signal.

33. The system according to claim 19, wherein the processor is further configured to distinguish single-reflection multipath signals from multiple-reflection multipath signals.

34. The system according to claim 19, wherein the processor is further configured to identify one or more true reflection surfaces responsible for producing the at least one multipath signal based on a statistical inference.

35. The system according to claim 19, wherein the processor is further configured to eliminate one or more erroneous mapping points that result from a proximity effect.