Method and system for determining the location of an electronic device using multi-tone frequency signals

• US 8,421,676 B2
• Filed: 07/26/2010
• Issued: 04/16/2013
• Est. Priority Date: 03/31/2008
• Status: Expired due to Fees

• Current Assignee: Golba LLC
• Original Assignee: Golba LLC
• Inventors: Moshfeghi, Mehran
• Primary Examiner(s): Phan, Dao
• Application Number:
  US12/843,868
• Publication Number:
  US 20110043407A1
• Time in Patent Office: 995 Days
• Field of Search: 342/442, 342/444, 342/453, 342457-458, 342463-465, 455/456.2, 455/456.3, 455/457
• US Class Current: 342/463
• CPC Class Codes: G01C 21/20 Instruments for performing navigational calculations G01C21/24, G01C21/26 take precedence
• CPC Class Codes: G01S 1/02 using radio waves G01S19/00 takes precedence
• CPC Class Codes: G01S 13/38 wherein more than one modulation frequency is used
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location

Abstract

Embodiments of the present invention include a method of determining a location of a mobile device. The method comprises transmitting a signal between a plurality of known locations and receiving signal at device of unknown location such as a mobile device. The signal may include multiple tones having different frequencies and resulting in sets of residual phase differences. The location of the mobile device may be determined using the known locations and the frequency and phase differences between the transmitted tones. In one embodiment, OFDM signals may be used between an access point and mobile device, for example, to determine the location of the mobile device.

Claims

1. A method of determining a location of an electronic device, the method comprising:

transmitting three or more signals between a first electronic device at an unknown location and a second electronic device comprising at least three antennas at known locations, the three or more signals each including a plurality of simultaneous tones having different frequencies;

determining a first phase difference between at least two tones having a first frequency difference in the three or more signals accumulated during transmission between the first electronic device and a first antenna of the second electronic device;

determining a second phase difference between at least two tones having a second frequency difference in the three or more signals accumulated during transmission between the first electronic device and a second antenna of the second electronic device;

determining a third phase difference between at least two tones having a third frequency difference in the three or more signals accumulated during transmission between the first electronic device and a third antenna of the second electronic device; and

determining the location of the first electronic device using said first, second, and third phase differences and said first, second, and third frequency differences.

2. The method of claim 1 further comprising:

transmitting one or more signals between the first electronic device and a third electronic device comprising a fourth antenna at a known location, the one or more signals each including a plurality of tones having different frequencies, the third electronic device different than the second electronic device; and

determining a fourth phase difference between at least two tones having a fourth frequency difference in the one or more signals accumulated during transmission between the first electronic device and the fourth antenna of the third electronic device, wherein said determining the location further comprises using the fourth phase difference and the fourth frequency difference.

3. The method of claim 1, wherein the at least three antennas comprise a fourth antenna at a known location, the method further comprising:

determining a fourth phase difference between at least two tones having a fourth frequency difference in the three or more signals accumulated during transmission between the first electronic device and the fourth antenna of the second electronic device, wherein said determining the location further comprises using the fourth phase difference and the fourth frequency difference.

4. The method of claim 1, wherein transmitting the three or more signals between the first electronic device and the second electronic device comprises sending the signals from each antenna of the second electronic device and receiving the signals at the first electronic device.

5. The method of claim 4, wherein each of the three or more antennas acts as a transmitter and a receiver of the second electronic device, wherein transmitting the three or more signals between the first electronic device and the second electronic device further comprises sending the signals from the first electronic device and receiving the signals at each antenna of the second electronic device.

6. The method of claim 1, wherein transmitting the three or more signals between the first electronic device and the second electronic device comprises sending the signals from the first electronic device and receiving the signals at each antenna of the second electronic device.

7. The method of claim 1, wherein determining the location of the first electronic device comprises sending signal information including the first, second, and third phase differences and the first, second, and third frequency differences to a location engine that processes the phase differences and frequency differences to determine distances between the first electronic device and each of the first, second, and third antennas of the second electronic device, the determined distances being used to triangulate the location of the first electronic device.

8. The method of claim 7, wherein the location engine to which the signal information is sent is located on a server communicatively coupled to at least one of the first and second electronic devices through a network.

9. The method of claim 7, wherein the location engine to which signal information is sent is located on one of the first and second electronic devices.

10. The method of claim 1, wherein the first electronic device is a mobile device, wherein the second electronic device is an access point, wherein the three or more antennas are antennas at known locations of the access point.

11. The method of claim 1, wherein a set of antennas with a best performance determined based on bit error rates is utilized.

12. The method of claim 1, wherein the location of the first electronic device is determined based on distances between the first electronic device and the first, second, and third antennas of the second electronic device, each of the distances being determined by solving a system of linear equations based on the phase differences, wherein the system of linear equations is solved by trial and error by inputting integer numbers representing full cycles for each tone.

13. The method of claim 1, wherein the first electronic device and the second electronic device utilize a plurality of wireless standards, the plurality of wireless standards comprising Ultra-Wideband and Wireless Local Area Network.

14. The method of claim 1, wherein the plurality of tones included in the three or more signals have a known phase difference at a time of transmission, wherein the location of the first electronic device is determined based on distances between the first electronic device and the first, second, and third antennas of the second electronic device, each of the distances being determined based on the measured accumulated phase differences and the known phase difference.

15. The method of claim 1, wherein the transmitted signals between the first electronic device and the second electronic device are analog signals, the method further comprising converting the analog signals into digital signals, wherein the phase differences are determined based on the converted digital signals.

16. The method of claim 1 further comprising interfacing the first electronic device with a navigation system to provide path planning and guidance when the location of the first electronic device is determined.

17. The method of claim 1 further comprising using the first electronic device as an access point of a known location to locate positions of other mobile devices when the location of the first electronic device is determined.

18. The method of claim 1, wherein the three or more signals comprise orthogonal frequency division multiplexed signals.

19. The method of claim 1 further comprising:

using amplitudes of each of the tones of the three or more signals to determine a received power, and

using an attenuation in the received power to determine distances between the first electronic device and the first, second, and third antennas of the second electronic device,

wherein determining the location of the first electronic device comprises using the determined distances to triangulate the location of the first electronic device.

20. The method of claim 19, further comprising assigning weights to each tone of the signals based on the amplitude of each tone relative to an average amplitude in order to reduce the effects of noise, fading, or multipath.