LOCATION DETERMINATION USING CACHED LOCATION AREA CODES

• US 20110177826A1
• Filed: 01/15/2010
• Published: 07/21/2011
• Est. Priority Date: 01/15/2010
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Mayor, Robert, Huang, Ronald K.
• Granted Patent: US 8,634,860 B2
• Time in Patent Office: Days
• US Class Current: 455/456.1
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

Methods, program products, and systems for location determination using cached location area codes are described. A mobile device can store a set of location area codes (LACs) of a cellular communications network on the mobile device. Each LAC can represent a location area of the cellular communications network that encompasses at least a predetermined number of cells. Each LAC can be further associated with an estimated geographic area. The estimated geographic area can be defined as a circle centered at a location and having a radius representing an uncertainty of the location. The mobile device can determine a current LAC of the mobile device based on a wirelessly received signal. The mobile device can determine a current location of the mobile device by performing a lookup in the stored set of LACs using the current LAC.

Claims

1. A method executed by a mobile device, comprising:

receiving a set of location area codes (LACs) of a cellular communications network, each LAC in the set being associated with at least a predetermined number of cells of the cellular communications network, the LAC further associated with a geographic area, the geographic area including a first circle centered at a location and having a first radius representing an uncertainty of the location;

determining a current LAC of the mobile device based on a wirelessly received signal; and

determining a current location of the mobile device, including performing a lookup in the stored set of LACs using the current LAC.

2. The method of claim 1, where each LAC corresponds to a location area, the location area encompassing at least the predetermined number of cells.

3. The method of claim 1, further comprising displaying the current location of the mobile device on a display device as the first circle centered at the location and having the first radius representing the uncertainty of the location.

4. The method of claim 3, where displaying the current location further includes displaying a second circle replacing the first circle, the second circle corresponding to an estimated location of the mobile device and having a second radius that is less than the first radius.

5. The method of claim 4, where the estimated location is calculated using operations comprising:

(a) receiving identifiers of access points of a wireless communications network and a set of locations associated with the access points;

(b) calculating an average geographic location using the set of locations;

(c) calculating distances between the average geographic location and locations in the set;

(d) excluding at least one location from the set based on a distance between the average geographic location and the at least one location;

(e) repeating (b), (c), and (d) until an exit condition is satisfied; and

(f) designating the estimated location of the mobile device using the second circle having the average geographic location as a center and the second radius based on at least one calculated distance.

6. The method of claim 5, where the identifiers of the access points include Media Access Control (MAC) addresses of the access points.

7. The method of claim 5, where the exit condition is satisfied when a number of repetitions reaches a threshold number.

8. The method of claim 5, where the exit condition is satisfied when the radius of the circle reaches below a threshold radius.

9. A system, comprising:

one or more mobile devices configured to perform operations comprising;

receiving a set of location area codes (LACs) of a cellular communications network, each LAC in the set being associated with at least a predetermined number of cells of the cellular communications network, the LAC further associated with a geographic area, the geographic area including a first circle centered at a location and having a first radius representing an uncertainty of the location;

determining a current LAC of the mobile device based on a wirelessly received signal; and

determining a current location of the mobile device, including performing a lookup in the stored set of LACs using the current LAC.

10. The system of claim 9, where each LAC corresponds to a location area, the location area encompassing at least the predetermined number of cells.

11. The system of claim 9, further comprising displaying the current location of the mobile device on a display device as the first circle centered at the location and having the first radius representing the uncertainty of the location.

12. The system of claim 11, where displaying the current location further includes displaying a second circle replacing the first circle, the second circle corresponding to an estimated location of the mobile device and having a second radius that is less than the first radius.

13. The system of claim 12, where the estimated location is calculated using operations comprising:

(a) receiving identifiers of access points of a wireless communications network and a set of locations associated with the access points;

(b) calculating an average geographic location using the set of locations;

(c) calculating distances between the average geographic location and locations in the set;

(d) excluding at least one location from the set based on a distance between the average geographic location and the at least one location;

(e) repeating (b), (c), and (d) until an exit condition is satisfied; and

(f) designating the estimated location of the mobile device using the second circle having the average geographic location as a center and the second radius based on at least one calculated distance.

14. The system of claim 13, where the identifiers of the access points include Media Access Control (MAC) addresses of the access points.

15. The system of claim 13, where the exit condition is satisfied when a number of repetitions reaches a threshold number.

16. The system of claim 13, where the exit condition is satisfied when the radius of the circle reaches below a threshold radius.

17. A computer program product tangibly stored on a storage device, operable to cause a mobile device to perform operations comprising:

receiving a set of location area codes (LACs) of a cellular communications network, each LAC in the set being associated with at least a predetermined number of cells of the cellular communications network, the LAC further associated with a geographic area, the geographic area including a first circle centered at a location and having a first radius representing an uncertainty of the location;

determining a current LAC of the mobile device based on a wirelessly received signal; and

determining a current location of the mobile device, including performing a lookup in the stored set of LACs using the current LAC.

18. The product of claim 17, where each LAC corresponds to a location area, the location area encompassing at least the predetermined number of cells.

19. The product of claim 17, further comprising displaying the current location of the mobile device on a display device as the first circle centered at the location and having the first radius representing the uncertainty of the location.

20. The product of claim 19, where displaying the current location further includes displaying a second circle replacing the first circle, the second circle corresponding to an estimated location of the mobile device and having a second radius that is less than the first radius.

21. The product of claim 20, where the estimated location is calculated using operations comprising:

(a) receiving identifiers of access points of a wireless communications network and a set of locations associated with the access points;

(b) calculating an average geographic location using the set of locations;

(c) calculating distances between the average geographic location and locations in the set;

(d) excluding at least one location from the set based on a distance between the average geographic location and the at least one location;

(e) repeating (b), (c), and (d) until an exit condition is satisfied; and

(f) designating the estimated location of the mobile device using the second circle having the average geographic location as a center and the second radius based on at least one calculated distance.

22. The product of claim 21, where the identifiers of the access points include Media Access Control (MAC) addresses of the access points.

23. The product of claim 21, where the exit condition is satisfied when a number of repetitions reaches a threshold number.

24. The product of claim 21, where the exit condition is satisfied when the radius of the circle reaches below a threshold radius.