WIRELESS POSITIONING SYSTEMS

• US 20160018508A1
• Filed: 01/26/2015
• Published: 01/21/2016
• Est. Priority Date: 07/17/2014
• Status: Active Grant

• Current Assignee: Origin Wireless, Inc.
• Original Assignee: Origin Wireless Communications, Inc.
• Inventors: Chen, Yan, Han, Yi, Liu, K. J. Ray, Wu, Zhung-Han, Hall, Katherine
• Granted Patent: US 10,168,414 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01S 5/0218 Multipath in signal reception
• CPC Class Codes: G01S 5/02521 using a radio-map

Abstract

A time-reversal positioning system includes a storage storing first data representing channel impulse responses derived from probe signals sent from a plurality of positions and second data representing coordinates of the positions. A data processor determines a position of a terminal device based on the stored channel impulse responses and a time-reversed signal determined based on a time-reversed version of a channel impulse response that is estimated based on a channel probing signal sent from the terminal device.

Claims

1. A method comprising:

at a first device, receiving a probe signal sent from a second device through a multipath channel, the probe signal received at the first device having a waveform that is different from the waveform sent by the second device due to influence of the multipath channel;

estimating a channel impulse response based on the probe signal received at the first device;

determining a time-reversed signal based on the estimated channel impulse response; and

determining a position of the second device based on the time-reversed signal and stored channel impulse responses that are stored in a storage device.

2. The method of claim 1 in which the stored channel impulse responses are derived from probe signals sent from a plurality of positions, each stored channel impulse response derived from a corresponding probe signal sent from a corresponding position, each stored channel impulse response being associated with the position from which the corresponding probe signal was sent.

3. The method of claim 2, comprising:

for each of a plurality of positions, determining a feature value based on a function of the time-reversed signal and the stored channel impulse response associated with the position, and

determining the position of the second device based on the position associated with a largest feature value among the feature values.

4. The method of claim 3 in which the feature value associated with a position is also a function of the stored channel impulse response or responses associated with one or more neighboring positions.

5. The method of claim 3 in which the feature value associated with a position is a function of the stored channel impulse responses derived from probe signals sent from the position at a plurality of time periods.

6. The method of claim 3 in which determining the feature value associated with a position comprises calculating a convolution of the time-reversed signal and the stored channel impulse response associated with the position.

7. The method of claim 1 in which the probe signal is modulated by a carrier wave, and determining a position of the second device comprises determining a position of the second device with an accuracy within one wavelength of the carrier wave.

8. The method of claim 7 in which determining a position of the second device comprises determining a position of the second device with an accuracy within one-half of a wavelength of the carrier wave.

9. The method of claim 8 in which determining a position of the second device comprises determining a position of the second device with an accuracy within one-tenth of a wavelength of the carrier wave.

10. The method of claim 1 in which the probe signal comprises one or more pulse signals.

11. The method of claim 1 in which the probe signal comprises one or more pseudorandom codes.

12. The method of claim 1 in which the probe signal comprises one or more Golay sequences.

13. The method of claim 1, comprising transmitting information about the position of the second device to the second device.

14. The method of claim 13, comprising transmitting the information about the position of the second device to the second device using time-reversal wireless communication.

15. The method of claim 1, comprising receiving coarse positioning data from the second device, selecting a subset of stored channel impulse responses based on the coarse positioning data, and determining the position of the second device based on the time-reversed signal and the subset of stored channel impulse responses.

16. An apparatus comprising:

a storage storing first data representing channel impulse responses derived from probe signals sent from a plurality of positions and second data representing coordinates of the positions.

17. The apparatus of claim 16, comprising a data processor configured to determine a position of a terminal device based on the stored channel impulse responses and a time-reversed signal determined based on a time-reversed version of a channel impulse response that is estimated based on a channel probing signal sent from the terminal device.

18. An apparatus comprising:

a circuit to receive a probe signal sent from a second device through a multipath channel, the probe signal received at the apparatus having a waveform that is different from the waveform sent by the second device due to influence of the multipath channel; and

a data processor configured to;

estimate a channel impulse response based on the received probe signal;

determine a time-reversed signal based on the estimated channel impulse response; and

determine a position of the second device based on the time-reversed signal and stored channel impulse responses that are stored in a storage device.

19. The apparatus of claim 18 in which the stored channel impulse responses are derived from probe signals sent from a plurality of positions, each stored channel impulse response derived from a corresponding probe signal sent from a corresponding position, each stored channel impulse response being associated with the position from which the corresponding probe signal was sent.

20. The apparatus of claim 19 in which the data processor is configured to:

for each of a plurality of positions, determine a feature value based on a function of the time-reversed signal and the stored channel impulse response associated with the position, and

determine the position of the second device based on the position associated with a largest feature value among the feature values.

21. The apparatus of claim 19 in which the feature value associated with a position is also a function of the stored channel impulse response or responses associated with one or more neighboring positions.

22. The apparatus of claim 19 in which the feature value associated with a position is a function of the stored channel impulse responses derived from probe signals sent from the position at a plurality of time periods.

23. The apparatus of claim 19 in which determine the feature value associated with a position comprises calculating a convolution of the time-reversed signal and the stored channel impulse response associated with the position.

24. The apparatus of claim 18 in which the probe signal comprises one or more pulse signals.

25. The apparatus of claim 18 in which the probe signal comprises one or more pseudorandom codes.

26. The apparatus of claim 18 in which the probe signal comprises one or more Golay sequences.

27. The apparatus of claim 18, comprising a transmit circuit to transmit information about the position of the second device to the second device.