TECHNIQUES FOR COMPUTING LOCATION OF A MOBILE DEVICE BASED ON OBSERVED WI-FI ACCESS POINTS

• US 20140342752A1
• Filed: 08/11/2014
• Published: 11/20/2014
• Est. Priority Date: 10/29/2004
• Status: Active Grant

• Current Assignee: Skyhook Wireless Incorporated (Liberty Broadband Corp.)
• Original Assignee: Skyhook Wireless Incorporated (Liberty Broadband Corp.)
• Inventors: Jones, Russel K., Alizadeh-Shabdiz, Farshid, Morgan, Edward J., Shean, Michael G.
• Granted Patent: US 9,369,884 B2
• Time in Patent Office: Days
• US Class Current: 455/456.1
• CPC Class Codes: G01S 19/13 Receivers
• CPC Class Codes: G01S 19/14 specially adapted for specific applications
• CPC Class Codes: G01S 19/46 the supplementary measurement being of a radio-wave signal type
• CPC Class Codes: G01S 5/0205 Details
• CPC Class Codes: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• CPC Class Codes: G01S 5/0226 Transmitters
• CPC Class Codes: G01S 5/0242 Determining the position of transmitters to be subsequently used in positioning G01S5/0289 takes precedence
• CPC Class Codes: G01S 5/02526 using non-dedicated equipment, e.g. user equipment or crowd-sourcing
• CPC Class Codes: G01S 5/0284 Relative positioning
• CPC Class Codes: G06Q 10/0875 Itemisation or classification of parts, supplies or services, e.g. bill of materials
• CPC Class Codes: G08G 1/20 Monitoring the location of vehicles belonging to a group, e.g. fleet of vehicles, countable or determined number of vehicles
• CPC Class Codes: H04W 16/18 Network planning tools
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 4/02 Services making use of location information
• CPC Class Codes: H04W 4/029 Location-based management or tracking services
• CPC Class Codes: H04W 48/08 Access restriction or access information delivery, e.g. discovery data delivery signalling during connection H04W76/00
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: H04W 64/003 locating network equipment
• CPC Class Codes: H04W 84/10 Small scale networks; Flat hierarchical networks
• CPC Class Codes: H04W 84/12 : WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 88/06 : adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals
• CPC Class Codes: H04W 88/08 : Access point devices
• CPC Class Codes: Y10S 707/99936 : Pattern matching access

Abstract

In one embodiment, characteristics of signals received from Wi-Fi access points during a traversal of a number of drivable streets within a geographic area having a radius of one or more miles are determined, the characteristics of a given signal including a unique identifier of a Wi-Fi access point that transmitted the signal, a location where the signal was observed, and an observed signal strength at the location where the signal was observed. Using the characteristics, a reference database is built including records descriptive of Wi-Fi access points in the geographic area. To determine a current location of a mobile device, an observed signal strength of one or more Wi-Fi access points observed by the mobile device from the current location is determined and a current location of the mobile device is computed using at least the observed signal strength of the one or more Wi-Fi access points observed by the mobile device in comparison to information in the reference database.

Claims

1. A method comprising:

determining characteristics of signals received from Wi-Fi access points during a traversal of a number of drivable streets within a geographic area having a radius of one or more miles, the characteristics of a given signal including a unique identifier of a Wi-Fi access point that transmitted the signal, a location where the signal was observed, and an observed signal strength at the location where the signal was observed;

using the characteristics to build a reference database including records storing information descriptive of Wi-Fi access points in the geographic area;

maintaining the reference database on a non-transitory computer readable medium;

receiving a request for a current location of a mobile device;

obtaining an observed signal strength of one or more Wi-Fi access points observed by the mobile device from the current location; and

computing the current location of the mobile device using at least the observed signal strength of the one or more Wi-Fi access points observed by the mobile device in comparison to the information descriptive of Wi-Fi access points in the geographic area in the reference database.

2. The method of claim 1, wherein the using further comprises:

calculating geographic location of each of the Wi-Fi access points in the geographic area based on locations where the signal of the Wi-Fi access point was observed and the observed signal strength at the locations where the signal of the Wi-Fi access point was observed; and

storing the geographic location of each of the Wi-Fi access points in the records of the reference database.

3. The method of claim 2, wherein the calculating utilizes a reverse triangulation algorithm.

4. The method of claim 3, wherein the reverse triangulation algorithm weights stronger signals more than weaker signals

5. The method of claim 1, wherein the using further comprises:

producing a power profile of each of the Wi-Fi access points in the geographic area based on locations where the signal of the Wi-Fi access point was observed and the observed signal strength at the locations where the signal of the Wi-Fi access point was observed, the power provide indicating signal power at a plurality of positions about the Wi-Fi access point; and

storing the power profile of each of the Wi-Fi access points in the records of the reference database

6. The method of claim 1, wherein the number is substantially all drivable streets within the geographic area.

7. The method of claim 1, wherein the traversal is conducted according to a programmatically-determined route.

8. The method of claim 1, further comprising:

filtering the records of the reference database to identify erroneous records, the filtering based upon clustering of records for a given Wi-Fi access point.

9. The method of claim 8, wherein the filtering further comprises:

calculating a weighted centroid for the given Wi-Fi access point; and

designating records for the given Wi-Fi access point whose distance from the weighted centroid exceeds a threshold as being erroneous records.

10. The method of claim 8, further comprising:

removing erroneous records from the reference database.

11. A system comprising:

a central network server configured to build records descriptive of Wi-Fi access points in a geographic area having a radius of one or more miles, based on characteristics of signals received from Wi-Fi access points during a traversal of a number of drivable streets within the geographic area, the characteristics of a given signal including a unique identifier of a Wi-Fi access point that transmitted the signal, a location where the signal was observed, and an observed signal strength at the location where the signal was observed; and

a reference database configured to maintain the records storing information descriptive of Wi-Fi access points in the geographic area,

wherein the central network server is further configured to compute a current location of a mobile device in response to receiving a request for a current location of the mobile device including an observed signal strength of one or more Wi-Fi access points observed by the mobile device from the current location, the computation of the current location of the mobile device based on at least a comparison of the observed signal strength of the one or more Wi-Fi access points observed by the mobile device to the information in the reference database.

12. The system of claim 11, wherein the central network server is configured to build the records by calculation of a geographic location of each of the Wi-Fi access points based on locations where the signal of the Wi-Fi access point was observed and the observed signal strength at the locations where the signal of the Wi-Fi access point was observed.

13. The system of claim 11, wherein the central network server is configured to build the records by producing a power profile of each of the Wi-Fi access points based on locations where the signal of the Wi-Fi access point was observed and the observed signal strength at the locations where the signal of the Wi-Fi access point was observed, the power profile indicating signal power at a plurality of positions about the Wi-Fi access point.

14. The system of claim 11, wherein the number is substantially all drivable streets within the geographic area.

15. The system of claim 11, wherein the traversal is conducted according to a programmatically-determined route.

16. A non-transitory computer-readable medium having instructions executable by one or more processors stored thereon that, the instructions when executed by the one or more processors operable to:

determine characteristics of signals received from Wi-Fi access points within a geographic area having a radius of one or more miles, the characteristics of a given signal including a unique identifier of a Wi-Fi access point that transmitted the signal, a location where the signal was observed, and an observed signal strength at the location where the signal was observed;

calculate a geographic location of each of the Wi-Fi access points based on locations where signals of the Wi-Fi access point were observed and the observed signal strength at the locations where signals of the Wi-Fi access point were observed;

store the calculated geographic location of each of the Wi-Fi access points in a reference database;

receive a request for a current location of a mobile device;

determine one or more Wi-Fi access points observed by the mobile device from the current location; and

compute the current location of the mobile device using at least the one or more Wi-Fi access points observed by the mobile device in comparison to the calculated geographic locations in the reference database.

17. The non-transitory computer-readable medium of claim 16 wherein the signals received from Wi-Fi access points within the geographic area are received as part of a traversal of drivable streets within the geographic area according to a programmatically-determined route.

18. The non-transitory computer-readable medium of claim 16, wherein the instructions when executed are further operable to:

filter the records of the reference database to identify erroneous records, wherein records that are outliers of a cluster are considered erroneous records.

19. The non-transitory computer-readable medium of claim 18, wherein the instructions that when executed are operable to filter include instructions that when executed are operable to:

calculate a weighted centroid for a given Wi-Fi access point; and

designate records associated with the given Wi-Fi access point whose distance from the weighted centroid exceeds a threshold as being erroneous records.

20. The non-transitory computer-readable medium of claim 18, wherein the instructions that when executed are operable to filter include instructions that when executed are operable to:

remove erroneous records from the reference database.