Methods and systems for determining the location of an electronic device using multi-tone frequency signals

• US 9,366,745 B2
• Filed: 06/11/2014
• Issued: 06/14/2016
• 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:
  US14/302,378
• Publication Number:
  US 20150006073A1
• Time in Patent Office: 734 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: 1/1
• 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 system for determining a location of an electronic device, the system comprising:

(i) a first electronic device comprising;

(a) a plurality of antennas located at known locations, the plurality of antennas comprising three or more antennas; and

(b) a receiver;

(ii) a second electronic device located at an unknown location, the second electronic device comprising;

(a) an antenna; and

(b) a transmitter; and

(iii) a location determination engine,

wherein the transmitter of the second electronic device is configured to transmit one or more signals from the antenna of the second electronic device to the first electronic device comprising said plurality of antennas located at known locations, each transmitted signal including a plurality of simultaneous pilot tones having different frequencies;

wherein the receiver of the first electronic device is configured to;

(a) determine a first accumulated phase difference between at least two pilot tones having a first frequency difference in a signal transmitted from the antenna of the second electronic device and received at a first antenna of the first electronic device;

(b) determine a second accumulated phase difference between at least two pilot tones having a second frequency difference in a signal transmitted from the antenna of the second electronic device and received at a second antenna of the first electronic device; and

(c) determine a third accumulated phase difference between at least two pilot tones having a third frequency difference in a signal transmitted from the antenna of the second electronic device and received at a third antenna of the first electronic device; and

wherein the location determination engine is configured to determine the location of the second electronic device using said first, second, and third accumulated phase differences and said first, second, and third frequency differences.

2. The system of claim 1, wherein the first electronic device comprises said location determination engine.

3. The system of claim 1 further comprising a server comprising said location determination engine, wherein the first electronic device is configured to send said first, second, and third phase differences and said first, second, and third frequency differences to the server through a network.

4. The system of claim 1, wherein the second electronic device comprises said location determination engine, wherein the first electronic device is configured to send said first, second, and third phase differences and said first, second, and third frequency differences to the second electronic device.

5. The system of claim 1, wherein the transmitter of the second electronic device comprises a pilot insertion component configured to insert said pilot tones into the signals transmitted from the transmitter of the second electronic device.

6. The system of claim 1, wherein the transmitter of the second electronic device is further configured to transmit said signals through a transmission channel, wherein the receiver of the first electronic device comprises:

a pilot extraction and channel estimation component configured to (i) extract said pilot tones from signals received at the plurality of the antennas of the first electronic device and (ii) estimate a frequency response vector for the transmission channel using the extracted pilot tones; and

a range engine configured to calculate said phase differences accumulated between said pilot tones using the estimated frequency response vector.

7. The system of claim 6, wherein the range engine is further configured to:

extract amplitudes of each received pilot tone;

use the amplitudes of each of the pilot tones of the one or more signals to determine a received power; and

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

8. The system of claim 7, wherein the location determination engine is further configured to determine the location of the second electronic device by using the determined distances to triangulate the location of the second electronic device.

9. The system of claim 7, wherein the range engine is further configured to assign weights to each pilot tone of the signals based on the amplitude of each pilot tone relative to an average amplitude in order to reduce the effects of noise, fading, or multipath.

10. The system of claim 1 further comprising:

a third electronic device comprising an antenna at a known location, wherein the third electronic device is configured to;

receive one or more signals each including a plurality of pilot tones having different frequencies at the antenna of the third electronic device from the antenna of the second electronic device; and

determine a fourth accumulated phase difference between at least two pilot tones having a fourth frequency difference in a signal transmitted from the antenna of the second electronic device and received at the antenna of the third electronic device,

wherein the location determination engine is further configured to use the fourth accumulated phase difference and the fourth frequency difference to determine the location of the second electronic device.

11. The system of claim 1, wherein the plurality of antennas of the first electronic device comprise a fourth antenna at a known location, wherein the receiver of the first electronic device is further configured to determine a fourth accumulated phase difference between at least two pilot tones having a fourth frequency difference in a signal transmitted from the antenna of the second electronic device and received at the fourth antenna of the first electronic device, wherein said determining the location by the location determination engine further comprises using the fourth accumulated phase difference and the fourth frequency difference.

12. The system of claim 1, wherein the first electronic device is an access point, wherein the second electronic device is a mobile device, wherein the plurality of antennas are antennas at known locations of the access point.

13. The system of claim 1, wherein the location determination engine is further configured to determine the location of the second electronic device based on distances between the second electronic device and the first, second, and third antennas of the first electronic device, each of the distances determined by solving a system of linear equations based on the accumulated phase differences, wherein the system of linear equations is solved by trial and error by inputting integer numbers representing full cycles for each pilot tone.

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

15. The system of claim 1, wherein the plurality of pilot tones included in the signals transmitted from the antenna of the second electronic device and received at the plurality of antennas of the first electronic device have a known phase difference at a time of transmission, wherein the location of the second electronic device is determined based on distances between the second electronic device and the first, second, and third antennas of the first electronic device, each of the distances determined based on the determined accumulated phase differences and the known phase difference.

16. The system of claim 1 further comprising a navigation system, wherein the second electronic device is configured to interface with the navigation system to provide path planning and guidance after the location of the second electronic device is determined.

17. The system of claim 1 further comprising a plurality of mobile devices, wherein the second electronic device is configured to function as an access point of a known location to locate positions of one or more mobile devices in the plurality of mobile devices after the location of the second electronic device is determined.

18. The system of claim 1, wherein the signals transmitted from the antenna of the second electronic device to the plurality of antennas of the first electronic device comprise orthogonal frequency division multiplexed (OFDM) signals.

19. The system of claim 1, wherein the transmitter of the second electronic device is further configured to transmit packet-based signals from the antenna of the second electronic device to the plurality of antennas of the first electronic device, wherein the packet-based signals include said pilot tones in a packet preamble.

20. The system of claim 1, wherein the transmitter of the second electronic device is further configured to transmit packet-based signals from the antenna of the second electronic device to the plurality of antennas of the first electronic device, wherein the packet-based signals include a set of packets that include said pilot tones.

21. A first electronic device, comprising:

a plurality of antennas located at known locations, the plurality of antennas comprising three or more antennas; and

a receiver, the receiver configured to;

receive one or more signals transmitted from a second electronic device located at an unknown location, each received signal including a plurality of simultaneous pilot tones having different frequencies;

determine a first accumulated phase difference between at least two pilot tones having a first frequency difference in a signal transmitted from the second electronic device and received at a first antenna of the first electronic device;

determine a second accumulated phase difference between at least two pilot tones having a second frequency difference in a signal transmitted from the second electronic device and received at a second antenna of the first electronic device;

determine a third accumulated phase difference between at least two pilot tones having a third frequency difference in a signal transmitted from the second electronic device and received at a third antenna of the first electronic device; and

wherein the first electronic device is configured to determine a location of the second electronic device using said first, second, and third accumulated phase differences and said first, second, and third frequency differences.

22. The electronic device of claim 21, wherein the receiver of the first electronic device is further configured to receive said signals through a transmission channel, wherein the receiver of the first electronic device comprises:

a pilot extraction and channel estimation component configured to (i) extract said pilot tones from signals received at the plurality of the antennas of the first electronic device and (ii) estimate a frequency response vector for the transmission channel using the extracted pilot tones; and

a range engine configured to calculate said phase differences accumulated between said pilot tones using the estimated frequency response vector.

23. The electronic device of claim 22, wherein the range engine is further configured to:

extract amplitudes of each received pilot tone;

use the amplitudes of each of the pilot tones of the one or more signals to determine a received power; and

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

24. The electronic device of claim 23, wherein the first electronic device is further configured to determine the location of the second electronic device by using the determined distances to triangulate the location of the second electronic device.

25. The electronic device of claim 23, wherein the range engine is further configured to assign weights to each pilot tone of the signals based on the amplitude of each pilot tone relative to an average amplitude in order to reduce the effects of noise, fading, or multipath.

26. The electronic device of claim 21, wherein the plurality of antennas of the first electronic device comprise a fourth antenna at a known location, wherein the receiver of the first electronic device is further configured to determine a fourth accumulated phase difference between at least two pilot tones having a fourth frequency difference in a signal transmitted from the second electronic device and received at the fourth antenna of the first electronic device, wherein said determining the location further comprises using the fourth accumulated phase difference and the fourth frequency difference.

27. The electronic device of claim 21, wherein the receiver of the first electronic device is further configured to:

determine a fourth accumulated phase difference between at least two pilot tones having a fourth frequency difference in a signal transmitted from the antenna of the second electronic device and received at an antenna of a third electronic device at a known location,

wherein the first electronic device is further configured to use the fourth accumulated phase difference and the fourth frequency difference to determine the location of the second electronic device.

28. The electronic device of claim 21, wherein the first electronic device is an access point, wherein the second electronic device is a mobile device, wherein the plurality of antennas are antennas at known locations of the access point.

29. The electronic device of claim 21, wherein the first electronic device is further configured to determine the location of the second electronic device based on distances between the second electronic device and the first, second, and third antennas of the first electronic device, each of the distances determined by solving a system of linear equations based on the accumulated phase differences, wherein the system of linear equations is solved by trial and error by inputting integer numbers representing full cycles for each pilot tone.

30. The electronic device of claim 21, wherein the first electronic device and the second electronic device utilize a plurality of wireless standards comprising Ultra-Wideband and Wireless Local Area Network.

31. The electronic device of claim 21, wherein the plurality of pilot tones included in the signals received at the plurality of antennas of the first electronic device from the second electronic device have a known phase difference at a time of transmission, wherein the location of the second electronic device is determined based on distances between the second electronic device and the first, second, and third antennas of the first electronic device, each of the distances determined based on the determined accumulated phase differences and the known phase difference.

32. The electronic device of claim 21, wherein the signals received at the plurality of antennas of the first electronic device from the second electronic device comprise orthogonal frequency division multiplexed (OFDM) signals.

33. The electronic device of claim 21, wherein the receiver of the first electronic device is further configured to receive packet-based signals from the second electronic device, wherein the packet-based signals include a plurality of pilot tones in a packet preamble.

34. The electronic device of claim 21, wherein the receiver of the first electronic device is further configured to receive packet-based signals from the second electronic device, wherein the packet-based signals include a set of packets that include a plurality of pilot tones.