ENHANCED CALIBRATION FOR MULTIPLE SIGNAL PROCESSING PATHS IN A FREQUENCY DIVISION DUPLEX SYSTEM

• US 20110095944A1
• Filed: 10/22/2009
• Published: 04/28/2011
• Est. Priority Date: 10/22/2009
• Status: Active Grant

• Current Assignee: Viavi Solutions, Inc. (Lumentum Holdings Inc.)
• Original Assignee: Reverb Networks Inc (Lumentum Holdings Inc.)
• Inventors: Kusyk, Richard Glenn
• Granted Patent: US 8,179,314 B2
• Time in Patent Office: Days
• US Class Current: 342/368
• 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 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 of calibrating signal processing paths for a plurality of transmission devices, the method comprising:

obtaining calibration data for at least one of the 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 for each of the plurality of transmission devices; and

determining if the phase variation is below a phase variation threshold and if the magnitude variation is below a magnitude variation threshold for each of the plurality of transmission devices,

wherein 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 plurality of transmission devices, then the plurality of calibration weights are applied to the at least one of the signal processing paths for each of the plurality of transmission devices.

2. The method of claim 1, further comprising:

calculating a signal-to-noise ratio of the calibration data for each of 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 each of the plurality of transmission devices,

wherein if the signal-to-noise ratio of the calibration data for any of the plurality of transmission devices is below the signal-to-noise ratio threshold then the plurality of calibration weights are not determined from the calibration data, the calibration data is discarded, and new calibration data is obtained for the at least one signal processing paths for each of the plurality of transmission devices.

3. The method of claim 1, wherein the obtaining of the calibration data for at least one of the signal processing paths includes inserting a calibration signal into a spectrum allotted to a carrier.

4. The method of claim 3, wherein the inserting of the calibration signal into the spectrum allotted to the carrier includes inserting the calibration signal in a spectrum between edges of a bandwidth of the carrier and a channel bandwidth of the spectrum allotted for the carrier.

5. The method of claim 3, wherein if the carrier is an uplink carrier,

(i) transmitting the calibration signal through a transmission path of a calibration transmission device,

(ii) looping the calibration signal and the carrier to a receiver path of one of the plurality of transmission devices,

(iii) receiving the calibration signal and the carrier from the one of the plurality of transmission devices, and

(iv) storing the received calibration signal and the carrier as the calibration data.

6. The method of claim 3, wherein if the carrier is a downlink carrier,

(i) transmitting the calibration signal and the carrier through a transmission path of one of the plurality of transmission devices,

(ii) looping the calibration signal and the carrier to a receiver path of a calibration transmission device,

(iii) receiving the calibration signal and the carrier from the calibration transmission device, and

(iv) storing the received calibration signal and the carrier as the calibration data.

7. The method of claim 1, further comprising:

determining a beamforming weight for each of the plurality of transmission devices by multiplying an ideal beamforming weight by the calibration weight for each of the plurality of transmission devices; and

applying the beamforming weights to the at least one signal processing paths for each of the plurality of transmission devices.

8. A system for calibrating signal processing paths for a plurality of transmission devices, the system comprising:

a calibration unit for obtaining calibration data for at least one of the signal processing paths;

a calibration weight determination unit for determining a plurality of calibration weights from the calibration data;

a variance calculation unit for calculating a calibration variance between the plurality of calibration weights, and for calculating a phase variation and a magnitude variation from the calibration data for each of the plurality of transmission devices; and

a threshold determination unit for determining if the calibration variance is below a calibration variance threshold, and determining if the phase variation is below a phase variation threshold and if the magnitude variation is below a magnitude variation threshold for each of the plurality of transmission devices,

wherein 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 plurality of transmission devices, then the plurality of calibration weights are applied to the at least one of the signal processing paths for each of the plurality of transmission devices.

9. The system of claim 8, further comprising

a signal-to-noise ratio calculating unit for calculating a signal-to-noise ratio of the calibration data for each of 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 each of the plurality of transmission devices,

wherein if the signal-to-noise ratio of the calibration data for any of the plurality of transmission devices is below the signal-to-noise ratio threshold then the plurality of calibration weights are not determined from the calibration data, the calibration data is discarded, and new calibration data is obtained for the at least one signal processing path for each of the plurality of transmission devices.

10. The system of claim 8, wherein the calibration unit inserts a calibration signal into the spectrum allotted to a carrier.

11. The system of claim 10, wherein the calibration unit inserts the calibration signal in a spectrum between edges of a bandwidth of the carrier and a channel bandwidth of the spectrum allotted for the carrier.

12. The system of claim 10, further comprising a calibration transmission device having a receiver path, and

wherein the at least one of the signal processing paths for each of the plurality of transmission devices includes a transmission path, and

wherein, if the carrier is a downlink carrier, the calibration unit obtains the calibration data from the receiver path of the calibration transmission device for each of the plurality of transmission devices by:

(i) transmitting the calibration signal and the carrier through the transmission path of one of the plurality of transmission devices;

(ii) looping the calibration signal and the carrier to the receiver path of the calibration transmission device;

(iii) receiving the calibration signal and the carrier from the calibration transmission device; and

(iv) storing the received calibration signal and the carrier as the calibration data.

13. The system of claim 10, further comprising a calibration transmission device having a transmitter path, and

wherein the at least one of the signal processing paths for each of the plurality of transmission devices includes a receiver path, and

wherein, if the carrier is an uplink carrier, the calibration unit obtains the calibration data from the receiver path for each of the plurality of transmission devices by:

(i) transmitting the calibration signal through the transmitter path of the calibration transmission device;

(ii) looping the calibration signal and the carrier to the receiver path of one of the transmission devices;

(iii) receiving the calibration signal and the carrier from the one of the plurality of transmission devices; and

(iv) storing the received calibration signal and the carrier as the calibration data.

14. The system of claim 8, further comprising:

a beamforming weight determination unit for determining a beamforming weight for each of the plurality of transmission devices by multiplying an ideal beamforming weight by the calibration weight for each of the plurality of transmission devices, and applying the beamforming weights to the at least one signal processing paths for each of the plurality of transmission devices.

15. A computer readable storage medium having a program stored thereon that when executed causes a computer to perform a method of calibrating signal processing paths for a plurality of transmission devices, the method comprising:

obtaining calibration data for at least one of the 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 for each of the plurality of transmission devices; and

determining if the phase variation is below a phase variation threshold and if the magnitude variation is below a magnitude variation threshold for each of the plurality of transmission devices,

wherein 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 plurality of transmission devices, then the plurality of calibration weights are applied to the at least one of the signal processing paths for each of the plurality of transmission devices.

16. The computer readable storage medium of claim 15, further comprising:

calculating a signal-to-noise ratio of the calibration data for each of 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 each of the plurality of transmission devices,

wherein if the signal-to-noise ratio of the calibration data for any of the plurality of transmission devices is below the signal-to-noise ratio threshold then the plurality of calibration weights are not determined from the calibration data, the calibration data is discarded, and new calibration data is obtained for the at least one signal processing paths for each of the plurality of transmission devices.

17. The computer readable storage medium of claim 15, wherein the obtaining of the calibration data for at least one of the signal processing paths includes inserting a calibration signal into a spectrum allotted to a carrier.

18. The computer readable storage medium of claim 17, wherein the inserting of the calibration signal into the spectrum allotted to the carrier includes inserting the calibration signal in a spectrum between edges of a bandwidth of the carrier and a channel bandwidth of the spectrum allotted for the carrier.

19. The computer readable storage medium of claim 17,

wherein if the carrier is an uplink carrier:

(i) transmitting the calibration signal through a transmission path of a calibration transmission device;

(ii) looping the calibration signal and the carrier to a receiver path of one of the plurality of transmission devices;

(iii) receiving the calibration signal and the carrier from the one of the plurality of transmission devices; and

(iv) storing the received calibration signal and the carrier as the calibration data, and

wherein if the carrier is a downlink carrier;

(i) transmitting the calibration signal and the carrier through a transmission path of one of the plurality of transmission devices;

(ii) looping the calibration signal and the carrier to a receiver path of a calibration transmission device;

(iii) receiving the carrier from the calibration transmission device; and

(iv) storing the received calibration signal and the carrier as the calibration data.

20. The computer readable storage medium of claim 15, further comprising:

determining a beamforming weight for each of the plurality of transmission devices by multiplying an ideal beamforming weight by the calibration weight for each of the plurality of transmission devices; and

applying the beamforming weights to the at least one signal processing paths for each of the plurality of transmission devices.