GEOLOCATION OF WIRELESS ACCESS POINTS FOR WIRELESS PLATFORMS

• US 20130093628A1
• Filed: 10/14/2011
• Published: 04/18/2013
• Est. Priority Date: 10/14/2011
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Roach, Kyle J., Jones, Eric B., Good, Kenneth R.
• Granted Patent: US 9,568,588 B2
• Time in Patent Office: Days
• US Class Current: 342/451
• CPC Class Codes: G01S 11/06 using intensity measurements
• CPC Class Codes: G01S 2013/466 by Trilateration, i.e. two antennas or two sensors determine separately the distance to a target, whereby with the knowledge of the baseline length, i.e. the distance between the antennas or sensors, the position data of the target is determined
• CPC Class Codes: G01S 2013/468 by Triangulation, i.e. two antennas or two sensors determine separately the bearing, direction or angle to a target, whereby with the knowledge of the baseline length, the position data of the target is determined
• CPC Class Codes: G01S 5/04 Position of source determined by a plurality of spaced direction-finders
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location

Abstract

A system and method for using a receiving wireless device to passively detect target wireless devices or access points, quantify signal strengths of the target wireless devices or access points, and accurately identify a position for, or geolocate, the target wireless devices or access points. A position of the receiving wireless device is determined and correlated with a signal strength received from a target wireless device taken from multiple positions of the receiving wireless device. A trilateration algorithm is applied to the correlated date to obtain coarse geographic positions for the target wireless device, then a filtering algorithm is applied to obtain an accurate position for the target wireless device, which is in turn displayed to a user of the receiving wireless device.

Claims

1. A method for identifying a location of at least one target wireless device, comprising:

determining a first location of a receiving wireless device;

detecting passively, with the receiving wireless device, a signal from at least one target wireless device in a vicinity of the receiving wireless device and assigning a value to a signal strength of the detected signal;

correlating the determined first location of the receiving wireless device with the value of the signal strength of the detected signal from the at least one target wireless device to result in first correlated data;

moving the receiving wireless device to a second location and to at least one third location and repeating the determining, detecting and correlating for the second location and the at least one third location to result in second correlated data and at least one third correlated data;

applying a trilateration algorithm, by a processor in the receiving wireless device, to the first correlated data, the second correlated data and the at least one third correlated data to determine a plurality of candidate locations for the at least one target wireless device;

applying a filtering algorithm, by the processor in the receiving wireless device, to the plurality of candidate locations for the at least one target wireless device to identify a location of the at least one target wireless device; and

outputting the identified location of the at least one target wireless device to a user of the receiving wireless device.

2. The method of claim 1, wherein all of the determining, detecting correlating, applying and outputting are accomplished autonomously by the receiving wireless device.

3. The method of claim 1, wherein the receiving device receives a signal from a global positioning satellite system to determine the first location, the second location and the at least one third location.

4. The method of claim 1, wherein the receiving wireless device detects passively the signal from the at least one target wireless device via a Wi-Fi receiver in the receiving wireless device.

5. The method of claim 1, further comprising determining whether sufficient correlated data is collected to apply the trilateration algorithm.

6. The method of claim 1, further comprising moving the receiving wireless device to at least another third location and repeating the determining, detecting and correlating for the at least the another third location to result in at least another third correlated data,

wherein the trilateration algorithm is applied additionally to the at least the another third correlated data.

7. The method of claim 1, wherein the value assigned to the signal strength of the detected signal is a calculated distance using a log-distance path loss model.

8. The method of claim 7, further comprising testing a range of path loss components.

9. The method of claim 7, wherein the calculated distance is a radius of a sphere and a correlated location of the receiving wireless device is a center point for the sphere for use in the trilateration algorithm for each location of the receiving wireless device.

10. The method of claim 1, wherein the filtering algorithm selects the candidate location with a smallest predicted error as the identified location of the at least one target wireless device.

11. The method of claim 1, wherein the identified location of the at least one target wireless device is output to the user of the receiving wireless device by being displayed on a display screen of the receiving wireless device.

12. The method of claim 1, wherein the receiving wireless device is a hand-held device.

13. The method of claim 12, wherein:

the hand-held device is one of a smartphone, a tablet and a PDA, and the hand-held device is a stand-alone device for performing all of the steps of the method.

23. A non-transitory computer-readable medium storing instructions which, when executed by a processor, cause the processor to execute the method of claim 1.

14. A receiving wireless device for identifying a location of at least one target wireless device, comprising:

a position reference device that determines a location of the receiving wireless device;

an external data communication interface configured as a receiver for receiving wireless signals passively from the at least one target wireless device in a vicinity of the receiving wireless device;

a storage device that stores at least a trilateration algorithm and a filtering algorithm for execution;

a processor that (1) assigns a value to a signal strength of the received signal, (2) correlates a location of the receiving wireless device with the value of the signal strength of the received signal from the at least one target wireless device to result in correlated data, (3) applies the trilateration algorithm to a plurality of the correlated data to determine a plurality of candidate locations for the at least one target wireless device, and (4) applies the filtering algorithm to the plurality of candidate locations for the at least one target wireless device to identify a location of the at least one target wireless device; and

an output device that outputs the identified location of the at least one target wireless device to a user of the receiving wireless device.

15. The receiving wireless device of claim 14, wherein the receiving wireless device is a hand-held device.

16. The receiving wireless device of claim 15, wherein the hand-held device is one of a smartphone, a tablet or a PDA

17. The receiving wireless device of claim 14, wherein the position reference device is a global positioning satellite system receiver.

18. The receiving wireless device of claim 14, wherein the wireless signals passively received by the receiving wireless device from the at least one target wireless device are Wi-Fi signals.

19. The receiving wireless device of claim 14, wherein the value that the processor assigns to the signal strength of the received signal is a calculated distance using a log-distance path loss model.

20. The receiving wireless device of claim 19, wherein the processor applies the calculated distance as a radius of a sphere and a correlated location of the receiving wireless device as a center point for the sphere for use in the trilateration algorithm for each location of the receiving wireless device.

21. The receiving wireless device of claim 14, wherein processor applies the filtering algorithm to select the candidate location with a smallest predicted error as the identified location of the at least one target wireless device.

22. The receiving wireless device of claim 14, further comprising a display screen, wherein the identified location of the at least one target wireless device is output to the user of the receiving wireless device by being displayed on the display screen.