System, method and database for determining location by indirectly using GPS coordinates
View Patent ↗A database stores results of scans for wireless (e.g., Wi-Fi) access points, some of them directly associated with GPS coordinates. Mobile electronic devices detect access points, details of which are sent to the database. Contents of the database are analyzed for relations between the scanned access points and previously stored GPS coordinates. If a relation is found, the GPS coordinates are used for determining or estimating the location of the mobile device.
1. A method of estimating locations of mobile devices, comprising:
receiving scan results of a first scan performed by a first mobile device, said scan results including Global Positioning System (GPS) coordinates of the first mobile device and including a first set of one or more access point identifiers, each access point identifier corresponding to a respective access point located in the first scan;
receiving scan results of a second scan performed by a second mobile device, said scan results of the second scan excluding coordinates of the second mobile device and including a second set of one or more access point identifiers, each of which corresponds to a respective access point located in the second scan;
detecting that the scan results of the first and second scans overlap by at least one access point;
estimating a location of the second mobile device to be within a first distance of the GPS coordinates;
receiving scan results of a third scan performed by a third mobile device, said scan results of the third scan excluding coordinates of the third mobile device and including a third set of one or more access point identifiers, each of which corresponds to a respective access point located in the third scan;
detecting that the scan results of the second and third scans overlap by at least one access point;
detecting that the scan results of the first and third scans do not overlap; and
estimating a location of the third mobile device to be within a second distance of the GPS coordinates, the second distance being larger than the first distance;
said method performed programmatically by a computing system.
2. The method of claim 1 , wherein estimating the location of the second mobile device comprises determining a boundary of a zone in which the second mobile device is estimated to be located.
3. The method of claim 2 , wherein the boundary is determined at least partly using trilateration.
4. The method of claim 1 , wherein the second distance is double the first distance.
5. The method of claim 1 , further comprising sending the estimated location of the second device to the second device.
6. The method of claim 1 , further comprising sending the estimated location of the third device to the third device.
7. The method of claim 1 , further comprising:
using the estimated location of the third device with another estimated location of the third device to calculate a weighted or average location; and
sending an indication of the weighted or average location to the third device.
8. The method according to claim 1 , wherein the first, second or third set of access point identifiers includes identifiers for less than all access points in the first, second or third scan respectively.
9. The method of claim 8 , wherein the included identifiers are for access points with strongest signal strengths.
10. The method of claim 8 , wherein the first, second and third sets of access point identifiers exclude identifiers of mobile devices and peer-to-peer devices.
11. The method of claim 1 , further comprising storing the scan results of the first, second and third scans in a database.
12. The method of claim 11 , further comprising storing timestamps with the scan results.
13. The method of claim 11 , wherein the database stores multiple first, second and third scan results from multiple first, second and third mobile devices, and the method further comprises:
determining that all access point identifiers in scan results of a given scan are each present in the database more than a set maximum number of times; and
deleting from the database the scan results of the given scan.
14. Non-transitory computer storage that stores executable program instructions that direct a computing system to perform a process that comprises:
receiving scan results of a first scan performed by a first mobile device, said scan results including Global Positioning System (GPS) coordinates of the first mobile device and including a first set of one or more access point identifiers, each access point identifier corresponding to a respective access point located in the first scan;
receiving scan results of a second scan performed by a second mobile device, said scan results of the second scan excluding coordinates of the second mobile device and including a second set of one or more access point identifiers, each of which corresponds to a respective access point located in the second scan;
detecting that the scan results of the first and second scans overlap by at least one access point;
estimating a location of the second mobile device to be within a first distance of the GPS coordinates;
receiving scan results of a third scan performed by a third mobile device, said scan results of the third scan excluding coordinates of the third mobile device and including a third set of one or more access point identifiers, each of which corresponds to a respective access point located in the third scan;
detecting that the scan results of the second and third scans overlap by at least one access point;
detecting that the scan results of the first and third scans do not overlap; and
estimating a location of the third mobile device to be within a second distance of the GPS coordinates, the second distance being larger than the first distance.
15. The non-transitory computer storage of claim 14 , wherein estimating the location of the second mobile device comprises determining a boundary of an zone in which the second mobile device is estimated to be located.
16. The non-transitory computer storage of claim 15 , wherein the boundary is determined at least partly using trilateration.
17. The non-transitory computer storage of claim 14 , wherein the second distance is double the first distance.
18. The non-transitory computer storage of claim 14 , wherein the process further comprises:
sending the estimated location of the second device to the second device; and
sending the estimated location of the third device to the third device.
19. The non-transitory computer storage of claim 14 , wherein the process further comprises storing the scan results of the first, second and third scans in a database.
20. The non-transitory computer storage of claim 19 , wherein the database stores multiple first, second and third scan results from multiple first, second and third mobile devices, and the process further comprises:
determining that all access point identifiers in scan results of a given scan are each present in the database more than a set maximum number of times; and
deleting from the database the scan results of the given scan.