Location tracking

• US 8,548,493 B2
• Filed: 05/25/2011
• Issued: 10/01/2013
• Est. Priority Date: 04/14/2011
• Status: Active Grant

• Current Assignee: HERE Global B.V. (Nokia Corporation)
• Original Assignee: Navteq B.V.
• Inventors: Rieger, Charles J. III
• Primary Examiner(s): PHUONG, DAI
• Application Number:
  US13/115,499
• Publication Number:
  US 20120264447A1
• Time in Patent Office: 860 Days
• Field of Search: 4554041-4042, 455/432.1, 4554323-4351, 455/436, 455440-441, 4554561-4563, 455/457
• US Class Current: 455/456.1
• CPC Class Codes: G01C 21/206 specially adapted for indoor navigation
• CPC Class Codes: G01S 5/02521 using a radio-map
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: H04W 4/025 using location based information parameters

Abstract

One or more systems, devices, and/or methods for tracking a wireless device are disclosed. For example, a method includes receiving signal strength data for each of a plurality of access points. The signal strength data from the plurality of access points is compared to identify an anchor access point having a highest signal strength. Remaining signal strength data from the plurality of access points are compared to a threshold signal strength to identify at least one attractor access point. A memory is accessed for locations of the anchor access point and the at least one attractor access point. A pull point is calculated along a line from the anchor access point to the at least one attractor access point. A location of the wireless device is estimated as an average of the pull point and the location of the anchor access point.

Claims

1. A method of tracking a wireless device, the method comprising:

receiving signal strength data for each of a plurality of access points;

comparing the signal strength data from the plurality of access points to identify an anchor access point having a highest signal strength;

comparing remaining signal strength data from the plurality of access points to a threshold signal strength to identify at least one attractor access point;

accessing a memory for coordinates of the anchor access point and coordinates of the at least one attractor access point;

calculating a pull point along a line from the anchor access point to the at least one attractor access point; and

estimating a location of the wireless device as an average of the pull point and the coordinates of the anchor access point.

2. The method of claim 1, wherein a distance between the pull point and the anchor access point is based on a signal strength of a respective attractor access point.

3. The method of claim 2, further comprising:

accessing a lookup table with the signal strength of the at least one attractor access point to retrieve a factor defining the distance between the pull point and the attractor access point.

4. The method of claim 1, further comprising:

scanning, using the wireless device, a radio space for the plurality of access points;

receiving, at the wireless device, a packet for each of the plurality of access points, the packet including a media access control address; and

determining, at the wireless device, the signal strength data for each of the plurality of access points based on received signal strengths associated with packets from each of the plurality of access points.

5. The method of claim 1, further comprising:

calculating the threshold signal strength as a predetermined level less than the highest signal strength, wherein signal strengths of each of the at least one attractor access points are greater than the threshold signal strength and less than the highest signal strength.

6. The method of claim 1, further comprising:

receiving a plurality of addresses, wherein each address corresponds to one of the plurality of access points; and

identifying the radio space based on the plurality of addresses.

7. The method of claim 1, further comprising:

receiving a radio map including a snap path;

comparing the estimated location of the wireless device to the snap path; and

determining a location on the snap path closest to the estimated location of the wireless device.

8. The method of claim 1, wherein comparing the signal strength data from the plurality of access points to identify the anchor access point having the highest signal strength comprises comparing the signal strength data to identify a plurality of anchor access points have a range of highest signal strengths.

9. The method of claim 8, wherein estimating the location of the wireless device comprises averaging a plurality of pull points and the locations of the plurality of anchor access points.

10. An apparatus for determining the location of a wireless device, the apparatus comprising:

a memory configured to store identities and locations for a plurality of access points;

a communication interface configured to receive signal strength data for each of the plurality of access points;

a controller configured to compare the signal strength data for the plurality of access points to identify an anchor access point and an attractor access point and configured to determine a location of the wireless device as an average of the location of the anchor access point and a pull point along a line from the anchor access point to the attractor access point, wherein the pull point is defined by a relative signal strength of the attractor access point.

11. The apparatus of claim 10, wherein the controller is further configured to designate an access point having a highest signal strength of the plurality of access points as the anchor access point.

12. The apparatus of claim 10, wherein the controller is further configured to designate each access point of the plurality of access points having a signal strength above a predetermined threshold as one of a plurality of attractor access points.

13. The apparatus of claim 10, wherein the controller is further configured to access a lookup table with the signal strength of the attractor access point to retrieve a factor defining a distance between the pull point and the attractor access point.

14. The apparatus of claim 10, wherein the communication interface is configured to scan a radio space for the plurality of access points and receive a packet including a media access control address for at least one of the plurality of access points, and wherein the controller is configured to calculate the signal strength data based on a received signal strength of the packet and configured to receive locations for the plurality of access points according to the media access control address.

15. The apparatus of claim 10, wherein the controller calculates the threshold signal strength as a predetermined level less than the highest signal strength.

16. The apparatus of claim 10, wherein the memory stores a radio map including a snap path, and the controller is configured to determine a location on the snap path closest to the estimated location of the wireless device.

17. A non-transitory computer readable medium configured to store a computer program configured to perform a method for location tracking of a wireless device, the method comprising:

receiving signal strength data for each of a plurality of communication beacons;

comparing the signal strength data to identify an anchor having a highest signal strength of the plurality of communication beacons;

comparing the signal strength data of the plurality of communication beacons except the anchor to a threshold signal strength;

if none of the signal strength data of the plurality of communication beacons except the anchor is greater than the threshold signal strength, estimating a location of the wireless device based on location data of the anchor; and

if any of the signal strength data of the plurality of communication beacons except the anchor is greater than the threshold signal strength, then;

designating at least one of the communication beacons, except the anchor, having signal strength data greater than the threshold signal strength as an attractor;

calculating location data for a pull point along a line from the anchor to the attractor; and

estimating a location of the wireless device as an average of the location data of the pull point and the location data of the anchor.

18. The non-transitory computer readable medium of claim 17, wherein the anchor or the attractor is an access point in communication with a network.

19. The non-transitory computer readable medium of claim 17, the method comprising:

receiving a radio map including a snap path;

comparing the estimated location of the wireless device to the snap path; and

determining a location on the snap path closest to the estimated location of the wireless device.

20. The non-transitory computer readable medium of claim 17, wherein comparing the signal strength data to identify the anchor having the highest signal strength comprises comparing the signal strength data to identify a plurality of anchors have a range of highest signal strengths.