LOCATION DETERMINATION USING FORMULA

• US 20090258660A1
• Filed: 04/15/2008
• Published: 10/15/2009
• Est. Priority Date: 04/15/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Carlisle, Patrick Block, Huang, Ronald Keryuan, van der Merwe, Rudolph, Low, Daryl Mun-Kid, Crandall, Richard Eugene, Bush, Jeffrey Alan
• Granted Patent: US 8,213,389 B2
• Time in Patent Office: Days
• US Class Current: 455/456.500
• CPC Class Codes: G01S 5/0221 Receivers

Abstract

Among other disclosed subject matter, a method includes obtaining, in a mobile device, power information indicating a detected power of respective signals received from multiple transmitters. The method includes determining a location of the mobile device using a formula that uses: locations of the multiple transmitters, a first function of the power information and a second function of respective locations of the multiple transmitters. The method can include recording the determined location.

Claims

1. A method comprising:

obtaining, in a mobile device, power information indicating a detected power of respective signals received from a plurality of transmitters; and

determining a location of the mobile device based at least in part on;

locations of the plurality of transmitters, a first function of the power information and a second function of respective locations of the plurality of transmitters.

2. The method of claim 1, further comprising:

displaying a map on a display of the mobile device;

receiving a user input in the mobile device indicating a request for the location to be determined; and

placing, in response to the user input, a first indicator on the map corresponding to the determined location and a second indicator indicating a determined certainty of the determined location.

3. The method of claim 1, wherein the location is determined based at least in part on a formula that depends on a log₁₀ of the detected power and a log₁₀ of a modeled transmitter power.

4. The method of claim 3, wherein the log₁₀ of the modeled transmitter power has a linear relationship with a log₁₀ of a distance between any of the plurality of transmitters and the mobile device.

5. The method of claim 4, wherein the linear relationship is:

10 log₁₀ F_n;

=10 log₁₀ γ

−

10 α

L

wherein

F_n is the modeled transmitter power of an nth transmitter;

γ and

α

are values; and

L equals log₁₀|r-r_n| wherein r is the location to be determined and r_n is the location of an nth transmitter.

6. The method of claim 5, further comprising:

determining γ and

α

before determining the location including analyzing detected power of signals received at known locations.

7. The method of claim 3, wherein the log₁₀ of the modeled transmitter power has a parabolic relationship with a log₁₀ of a distance between any of the plurality of transmitters and the mobile device.

8. The method of claim 7, wherein the parabolic relationship is:

10 log₁₀ F_n;

=a₀+a₁L+a₂L²

wherein

F_n is the modeled transmitter power of an nth transmitter;

a₀, a₁ and a₂ are values; and

L equals log₁₀|r-r_n| wherein r is the location to be determined and r_n is the location of an nth transmitter.

9. The method of claim 8, further comprising:

determining a₀, a₁ and a₂ before determining the location including analyzing detected power of signals received at known locations.

10. The method of claim 1, wherein the location is determined based at least in part on a formula that includes:

11. The method of claim 1, further comprising:

partitioning the plurality of transmitters into groups of a predefined number of transmitters according to all possible groupings of the plurality of transmitters;

wherein determining the location comprises determining a preliminary location, for each of the groups, using at least the information indicating the detected power from the transmitters in the group; and

selecting the location from among the determined preliminary locations.

12. The method of claim 11, wherein the location is selected based on a value of a formula for the corresponding group, the formula using the locations of the plurality of transmitters, the first function and the second function.

13. The method of claim 11, wherein the location is selected based on a clustering of the preliminary locations.

14. The method of claim 1, further comprising:

comparing the determined location to a predetermined number of locations determined previously; and

rejecting the determined location upon determining that a difference in the determined location exceeds a threshold.

15. The method of claim 1, further comprising:

storing earlier power information indicating a detected power of respective signals received earlier from the plurality of transmitters;

comparing the obtained power information with the earlier power information before determining the location.

16. The method of claim 15, further comprising:

removing at least part of the power information for at least one of the plurality of transmitters upon determining that a difference in the detected power for the transmitter exceeds a threshold.

17. A computer program product, encoded on a tangible program carrier, operable to cause a portable device to perform operations comprising:

obtaining, in a mobile device, power information indicating a detected power of respective signals received from a plurality of transmitters; and

determining a location of the mobile device based at least in part on;

locations of the plurality of transmitters, a first function of the power information and a second function of respective locations of the plurality of transmitters.

18. A method comprising:

obtaining, in a mobile device, power information indicating a detected power of respective signals received from a plurality of transmitters; and

determining a location of the mobile device based at least in part on a first function of respective locations of the plurality of transmitters, the first function using at least one value determined by analyzing detected power of signals received at known locations.

19. The method of claim 18, wherein the first function is:

20. The method of claim 19, wherein the location is determined based at least in part on a formula that includes