Enhanced calibration for multiple signal processing paths in a wireless network

• US 8,219,035 B2
• Filed: 09/18/2009
• Issued: 07/10/2012
• Est. Priority Date: 09/18/2009
• Status: Active Grant

• Current Assignee: Viavi Solutions, Inc. (Lumentum Holdings Inc.)
• Original Assignee: Reverb Networks
• Inventors: Kusyk, Richard Glenn
• Primary Examiner(s): Pham, Tuan
• Application Number:
  US12/562,378
• Publication Number:
  US 20110068971A1
• Time in Patent Office: 1,026 Days
• Field of Search: 455/67.11, 455/67.14, 455/67.16, 455/115.1, 455/115.2, 455/226.1, 455/226.3
• US Class Current: 455/67.11
• CPC Class Codes: G01S 7/4052 by simulation of echoes
• CPC Class Codes: G01S 7/406 using internally generated reference signals, e.g. via delay line, via RF or IF signal injection or via integrated reference reflector or transponder
• CPC Class Codes: H01Q 3/267 Phased-array testing or checking devices

Abstract

Calibrating signal processing paths for a plurality of transmission devices by obtaining calibration data for at least one of the signal processing paths for each of the transmission devices and determining a plurality of calibration weights from the calibration data for each of the transmission devices. A calibration variance is calculated between the plurality of calibration weights and it is determined if the calibration variance is below a calibration variance threshold. Additionally, a phase variation and a magnitude variation are calculated from the calibration data for each of the transmission devices with respect to a reference transmission signal obtained from a reference transmission device and it is determined for each of the transmission devices if the phase variation is below a phase variation threshold and if the magnitude variation is below a magnitude variation threshold. Further, if the calibration variance is below the calibration variance threshold, and the phase variation is below the phase variation threshold and the magnitude variation is below the magnitude variation threshold for each of the transmission devices, then the plurality of calibration weights are applied to the at least one of the signal processing paths of each of the transmission devices.

Claims

1. A method, comprising:

obtaining calibration data for each transmission device from a plurality of transmission devices associated with a plurality of signal processing paths;

determining a plurality of calibration weights from the calibration data for each transmission device from the plurality transmission devices;

calculating a calibration variance between the plurality of calibration weights and determining if the calibration variance is below a calibration variance threshold;

calculating, for each signal processing path from the plurality of signal processing paths, a phase variation and a magnitude variation from the calibration data with respect to a reference transmission signal obtained from a reference transmission device;

determining if the phase variation is below a phase variation threshold and if the magnitude variation is below a magnitude variation threshold for each signal processing path from the plurality of signal processing paths,

applying a calibration weight from the plurality of calibration weights to a signal processing path from the plurality of signal processing paths when the calibration variance is below the calibration variance threshold, the phase variation associated with that signal processing path is below the phase variation threshold and the magnitude variation associated with that signal processing path is below the magnitude variation threshold.

2. The method of claim 1, further comprising:

calculating, for each signal processing path from the plurality of signal processing paths, a signal-to-noise ratio of the calibration data; and

determining if the signal-to-noise ratio of the calibration data is below a signal-to-noise ratio threshold for each signal processing path from the plurality of signal processing paths,

if the signal-to-noise ratio of the calibration data for any signal processing path from the plurality of signal processing paths is below the signal-to-noise ratio threshold then discarding the calibration data, and obtaining new calibration data for each transmission device from the plurality of transmission devices.

3. The method of claim 1, further comprising:

calculating, for each signal processing path from the plurality of signal processing paths, a signal-to-DC ratio of the calibration data; and

determining if the signal-to-DC ratio of the calibration data is below a signal-to-DC ratio threshold for each signal processing path from the plurality of signal processing paths

if the signal-to-DC ratio of the calibration data for any signal processing path from the plurality of signal processing paths is below the signal-to-DC ratio threshold then discarding the calibration data, and obtaining new calibration data for each transmission device from the plurality of transmission devices.

4. The method of claim 1, wherein the obtaining of the calibration data includes:

obtaining the calibration data from a transmission path associated with a signal processing path from the plurality of signal processing paths;

or

obtaining the calibration data from a receiver path associated with a signal processing path from the plurality of signal processing paths.

5. The method of calibrating of claim 4, wherein the obtaining of the calibration data from the transmission path includes:

(i) sending a reference calibration signal through the transmission path;

(ii) looping the reference calibration signal to a receiver path of a calibration device;

(iii) receiving the reference calibration signal from the calibration device; and

(iv) storing the received reference calibration signal as the calibration data.

6. The method of claim 4, wherein the obtaining of the calibration data from the receiver path includes:

(i) sending a reference calibration signal through a transmitter path of a calibration device;

(ii) looping the reference calibration signal to the receiver path;

(iii) receiving the reference calibration signal from the signal processing path from the plurality of signal processing paths; and

(iv) storing the received reference calibration signal as the calibration data.

7. The method of claim 1, further comprising:

determining a beamforming weight for a transmission device from the plurality of transmission devices by multiplying an ideal beamforming weight by a calibration weight from the plurality of calibration weights for that transmission device from the plurality of transmission devices; and

applying the beamforming weight for that transmission device from the plurality of transmission devices to a signal processing path from the plurality of signal processing paths associated with that transmission device from the plurality of transmission devices.

8. The method of claim 1, wherein a transmission device from the plurality of transmission devices is set as the reference transmission device.

9. A method, comprising:

obtaining calibration data for each transmission device from a plurality of transmission devices associated with a plurality of signal processing paths;

calculating, for each signal processing path from the plurality of signal processing paths, a signal-to-noise ratio of the calibration data and determining if the signal-to-noise ratio of the calibration data is below a signal-to-noise ratio threshold for each signal processing path from the plurality of signal processing paths;

calculating, for each signal processing path from the plurality of signal processing paths, a signal-to-DC ratio of the calibration data and determining if the signal-to-DC ratio of the calibration data is below a signal-to-DC ratio threshold for each signal processing path from the plurality of signal processing paths;

determining a plurality of calibration weights from the calibration data;

calculating a calibration variance between the plurality of calibration weights and determining if the calibration variance is below a calibration variance threshold;

calculating, for each signal processing path from the plurality of signal processing paths, a phase variation and a magnitude variation from the calibration data with respect to a reference transmission signal obtained from a reference transmission device;

determining if the phase variation is below a phase variation threshold and if the magnitude variation is below a magnitude variation threshold for each signal processing path from the plurality of signal processing paths;

discarding the calibration data and obtaining new calibration data for each transmission device from the plurality of transmission devices if the signal-to-noise ratio of the calibration data for any signal processing path from the plurality of signal processing paths is below the signal-to-noise ratio threshold or if the signal-to-DC ratio of the calibration data for any signal processing path from the plurality of signal processing paths is below the signal-to-DC ratio threshold; and

applying a calibration weight from the plurality of calibration weights to a signal processing from the plurality of signal processing paths when the calibration variance is below the calibration variance threshold, the phase variation associated with that signal processing path is below the phase variation threshold and the magnitude variation associated with that signal processing path is below the magnitude variation threshold.

10. A system, comprising:

a calibration unit configured to obtain calibration data for each transmission device from a plurality of transmission devices associated with a plurality of signal processing paths;

a calibration weight determination unit configured to determine a plurality of calibration weights from the calibration data;

a reference transmission device configured to store a reference transmission signal;

a variance calculation unit operatively coupled to the reference transmission device, the variance calculation unit configured to calculate a calibration variance between the plurality of calibration weights, and configured to calculate a phase variation and a magnitude variation from the calibration data with respect to the reference transmission signal for each signal processing path from the plurality of signal processing paths; and

a threshold determination unit configured to determine if the calibration variance is below a calibration variance threshold, and configured to determine if the phase variation for a signal processing path from the plurality of signal processing paths is below a phase variation threshold and if the magnitude variation for the signal processing path is below a magnitude variation threshold,

a calibration weight from the plurality of calibration weights being applied to the signal processing path from the plurality of signal processing paths if the calibration variance is below the calibration variance threshold, the phase variation for the signal processing path is below the phase variation threshold, and the magnitude variation for the signal processing path is below the magnitude variation threshold.

11. The system of claim 10, further comprising a signal-to-noise ratio calculating unit configured to calculate, for each signal processing path from the plurality of signal processing paths, a signal-to-noise ratio of the calibration data, and configured to determine if the signal-to-noise ratio of the calibration data is below a signal-to-noise ratio threshold for each signal processing path from the plurality of signal processing paths,

if the signal-to-noise ratio of the calibration data for any signal processing path from the plurality of signal processing paths is below the signal-to-noise ratio threshold then discarding the calibration data, the calibration data, and obtain new calibration data for each transmission device from the plurality of transmission devices.

12. The system of claim 10, further comprising

a signal-to-DC ratio calculation unit configured to calculate, for each signal processing path from the plurality of signal processing paths, a signal-to-DC ratio of the calibration data for each signal processing path from the plurality of signal processing paths, the signal-to-DC ratio calculation unit configured to determine if the signal-to-DC ratio of the calibration data is below a signal-to-DC ratio threshold for each signal processing path from the plurality of signal processing paths,

if the signal-to-DC ratio of the calibration data for any signal processing path the plurality of signal processing paths is below the signal-to-DC ratio threshold then discarding the calibration data, and obtaining new calibration data for the each transmission device from the plurality of transmission devices.

13. The system of claim 10, wherein each signal processing path from the plurality of signal processing paths includes a transmission path or a receiver path,

the calibration unit including:

a transmission calibration unit configured to obtain the calibration data from the transmission path of a signal processing path from the plurality of signal processing paths;

or

a receiver calibration unit configured to obtain the calibration data from the receiver path of a signal processing path from the plurality of signal processing paths.

14. The system of claim 13, further comprising a calibration device having a receiver path, the transmission calibration unit configured to obtain the calibration data from the transmission path of the signal processing path from the plurality of signal processing paths by:

(i) sending a reference calibration signal through the transmission path;

(ii) looping the reference calibration signal to the receiver path of the calibration device;

(iii) receiving the reference calibration signal from the calibration device; and

(iv) storing the received reference calibration signal as the calibration data.

15. The system of claim 13, further comprising a calibration device having a transmitter path, the receiver calibration unit configured to obtain the calibration data from the receiver path of the signal processing path from the plurality of signal processing paths by:

(i) sending a reference calibration signal through the transmitter path of the calibration device;

(ii) looping the reference calibration signal to the receiver path;

(iii) receiving the reference calibration signal from the signal processing path from the plurality of signal processing paths; and

(iv) storing the received reference calibration signal as the calibration data.

16. The system of claim 10, further comprising:

a beamforming weight determination unit configured to determine a beamforming weight for a transmission device from the plurality of transmission devices by multiplying an ideal beamforming weight by a calibration weight from the plurality of calibration weights for that transmission device from the plurality of transmission devices, the beamforming weight determination unit configured to apply the beamforming weight for that transmission device from the plurality of transmission devices to a signal processing path from the plurality of signal processing paths associated with that transmission device from the plurality of transmission devices.

17. A system, comprising:

a calibration unit configured to obtain calibration data for each transmission device from a plurality of transmission devices associated with a plurality of signal processing devices;

a calibration weight determination unit configured to determine a plurality of calibration weights from the calibration data;

a signal-to-noise calculation unit configured to calculate, for each signal processing path from the plurality of signal processing paths, a signal-to-noise ratio of the calibration data;

a signal-to-DC calculation unit configured to calculate, for each signal processing path from the plurality of signal processing paths, a signal-to-DC ratio of the calibration data;

a reference transmission device configured to store a reference transmission signal;

a variance calculation unit configured to calculate a calibration variance between the plurality of calibration weights, and configured to calculate a phase variation and a magnitude variation for the calibration data for each transmission device from the plurality of transmission devices with respect to the reference transmission signal;

a threshold determination unit configured to determine if the calibration variance is below a calibration variance threshold, and configured to determine if the phase variation for a signal processing path from the plurality of signal processing paths is below a phase variation threshold, if the magnitude variation for the signal processing path is below a magnitude variation threshold, if the signal-to-noise ratio is below a signal-to-noise ratio threshold for the signal processing path, and if the signal-to-DC ratio is below a signal-to-DC ratio threshold for the signal processing path

if the signal-to-noise ratio of the calibration data for any signal processing path from the plurality of signal processing paths is below the signal-to-noise ratio threshold or if the signal-to-DC ratio of the calibration data for any signal processing path from the plurality of signal processing paths is below the signal-to-DC ratio threshold, then discarding the calibration data, and obtaining new calibration data for each transmission device from the plurality of transmission devices; and

a calibration weight application unit configured to apply a calibration weight from the plurality of calibration weights to the signal processing path from the plurality of signal processing paths if the calibration variance is below the calibration variance threshold, the phase variation for the signal processing path is below the phase variation threshold and the magnitude variation for the signal processing path is below the magnitude variation threshold.

18. A non-transitory computer readable storage medium having a program stored thereon that when executed causes a computer to perform a method, comprising:

obtaining calibration data for each transmission device from a plurality of transmission devices associated with a plurality of signal processing paths;

determining a plurality of calibration weights from the calibration data;

calculating a calibration variance between the plurality of calibration weights and determining if the calibration variance is below a calibration variance threshold;

calculating a phase variation and a magnitude variation from the calibration data with respect to a reference transmission signal obtained from a reference transmission device for each signal processing path from the plurality of signal processing paths;

determining if the phase variation is below a phase variation threshold and if the magnitude variation is below a magnitude variation threshold for each signal processing path from the plurality of signal processing paths; and

applying a calibration weight from the plurality of calibration weights to a signal processing path from the plurality of signal processing paths when the calibration variance is below the calibration variance threshold, the phase variation associated with that signal processing path is below the phase variation threshold and the magnitude variation associated with that signal processing path is below the magnitude variation threshold.

19. The non-transitory computer readable storage medium of claim 18, further comprising:

calculating, for each signal processing path from the plurality of signal processing paths, a signal-to-noise ratio of the calibration data; and

determining if the signal-to-noise ratio of the calibration data is below a signal-to-noise ratio threshold for each signal processing path from the plurality of signal processing paths,

if the signal-to-noise ratio of the calibration data for any signal processing path from the plurality of signal processing paths is below the signal-to-noise ratio threshold then discarding the calibration data, and obtaining new calibration data for each transmission device from the plurality of transmission devices.

20. The non-transitory computer readable storage medium of claim 18, further comprising:

calculating, for each signal processing path from the plurality of signal processing paths, a signal-to-DC ratio of the calibration data; and

determining if the signal-to-DC ratio of the calibration data is below a signal-to-DC ratio threshold for each signal processing path from the plurality of signal processing paths,

if the signal-to-DC ratio of the calibration data for any signal processing path from the plurality of signal processing paths is below the signal-to-DC ratio threshold then discarding the calibration data, and obtaining new calibration data for each transmission device from the plurality of transmission devices.

21. The non-transitory computer readable storage medium of claim 18, wherein the obtaining of the calibration data includes:

obtaining the calibration data from a transmission path associated with a signal processing path from the plurality of signal processing paths;

or

obtaining the calibration data from a receiver path associated with a signal processing path from the plurality of signal processing paths.

22. The non-transitory computer readable storage medium of claim 21, wherein the obtaining of the calibration data from the transmission path includes:

(i) sending a reference calibration signal through the transmission path;

(ii) looping the reference calibration signal to a receiver path of a calibration device;

(iii) receiving the reference calibration signal from the calibration device; and

(iv) storing the received reference calibration signal as the calibration data.

23. The non-transitory computer readable storage medium of claim 21, wherein the obtaining of the calibration data from the receiver path includes:

(i) sending a reference calibration signal through a transmitter path of a calibration device;

(ii) looping the reference calibration signal to the receiver path;

(iii) receiving the reference calibration signal from the signal processing path from the plurality of signal processing paths; and

(iv) storing the received reference calibration signal as the calibration data.

24. The non-transitory computer readable storage medium of claim 18, further comprising:

determining a beamforming weight for a transmission device from the plurality of transmission devices by multiplying an ideal beamforming weight by a calibration weight from the plurality of calibration weights for that transmission device from the plurality of transmission devices; and

applying the beamforming weight for that transmission device from the plurality of transmission devices to a signal processing path from the plurality of signal processing paths associated with that transmission device from the plurality of transmission devices.

25. The non-transitory computer readable storage medium of claim 18, wherein a transmission device from the plurality of transmission devices is set as the reference transmission device.

26. A non-transitory computer readable storage medium having a program stored thereon that when executed causes a computer to perform a method, comprising:

obtaining calibration data for each transmission device from a plurality of transmission devices, each transmission device from the plurality of transmission devices being associated with at least one signal processing path;

calculating a signal-to-noise ratio of the calibration data for the at least one signal processing path for each transmission device from the plurality of transmission devices, and determining if the signal-to-noise ratio of the calibration data is below a signal-to-noise ratio threshold for the at least one signal processing path for each transmission device from the plurality of transmission devices;

calculating a signal-to-DC ratio of the calibration data for the at least one signal processing path for each transmission device from the plurality of transmission devices, and determining if the signal-to-DC ratio of the calibration data is below a signal-to-DC ratio threshold for the at least one signal processing path for each transmission device from the plurality of transmission devices;

determining a plurality of calibration weights from the calibration data;

calculating a calibration variance between the plurality of calibration weights and determining if the calibration variance is below a calibration variance threshold;

calculating a phase variation and a magnitude variation from the calibration data for the at least one signal processing path for each transmission device from the plurality of transmission devices with respect to a reference transmission signal obtained from a reference transmission device; and

determining if the phase variation is below a phase variation threshold and if the magnitude variation is below a magnitude variation threshold for the at least one signal processing path for each transmission device from the plurality of transmission devices,

discarding the calibration data and obtaining new calibration data for the at least one signal processing path for each transmission device from the plurality of transmission devices if the signal-to-noise ratio of the calibration data for the at least one signal processing path for any of the plurality of transmission devices is below the signal-to-noise ratio threshold or if the signal-to-DC ratio of the calibration data for the at least one signal processing path for any of the plurality of transmission devices is below the signal-to-DC ratio threshold; and

applying a calibration weight from the plurality of calibration weights to the at least one signal processing path for a transmission device from the plurality of transmission devices if the calibration variance is below the calibration variance threshold, the phase variation for the at least one signal processing path for that transmission device is below the phase variation threshold and the magnitude variation for the at least one signal processing path for that transmission device is below the magnitude variation threshold.