Automatic array calibration scheme for wireless point-to-multipoint communication networks
First Claim
1. An antenna array calibration apparatus comprising:
- a calibration signal generating unit which generates a calibration signal from a coherent source;
a calibration signal injecting unit which is operable to selectively inject said calibration signal as an input signal;
a receiver unit which receives said input signal and obtains a channel signal from said input signal;
a reception data channel unit which receives said channel signal and generates a first set of I/Q signals; and
a controller which controls said calibration signal injecting unit to selectively insert said calibration signal as said input signal, and receives said first set of I/Q signals from said reception data channel unit, wherein said controller calculates a reception data channel offset based on said first set of I/Q signals.
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Abstract
An automatic array calibration apparatus which is capable of periodically calibrating beamforming offsets using internally generated calibration and test signals. The apparatus preferably includes a calibration signal generating unit which generates a continuous wave calibration signal which is input into a receiving channel as the input signal. I/Q signals are obtained from reception data channels which have been provided with the calibration signal. The apparatus also includes a loop back operation in which test signals are injected in transmission data channels, and are prepared for transmission at a transmission unit. The transmission signal is looped back to the receiving unit and I/Q signals are obtained from reception data channels supplied with the transmission signals.
91 Citations
17 Claims
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1. An antenna array calibration apparatus comprising:
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a calibration signal generating unit which generates a calibration signal from a coherent source;
a calibration signal injecting unit which is operable to selectively inject said calibration signal as an input signal;
a receiver unit which receives said input signal and obtains a channel signal from said input signal;
a reception data channel unit which receives said channel signal and generates a first set of I/Q signals; and
a controller which controls said calibration signal injecting unit to selectively insert said calibration signal as said input signal, and receives said first set of I/Q signals from said reception data channel unit, wherein said controller calculates a reception data channel offset based on said first set of I/Q signals. - View Dependent Claims (2, 3, 4, 5, 6, 7)
a transmission data channel unit which includes a transmission data channel, said transmission data channel being provided with a test signal;
a transmission unit which generates a transmission signal based on said transmission data channel;
a loop back unit which selectively provides said transmission signal as said input signal, wherein said controller controls said loop back unit to selectively provide said transmission signal as said input signal, said reception data channel unit generates a second set of I/Q signals based on said transmission signal provided as said input signal, and provides said second set of I/Q signals to said controller, and said controller calculates a loop back offset based on said second set of I/Q signals.
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4. The antenna array calibration apparatus of claim 3, wherein said controller calculates transmission channel offset according to the equation:
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5. The antenna array calibration apparatus of claim 4, wherein said controller calculates a modification vector according to the equation:
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6. The antenna array calibration apparatus of claim 5, wherein said controller calculates a transmission beamforming vector according to the equation:
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7. The antenna array calibration apparatus of claim 3, wherein said transmission unit comprises a plurality of transmission data channels, and each channel of said plurality of transmission data channels is simultaneously selectively injected with a test signal when said loop back unit selectively provides said transmission signal as said input signal.
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8. A method of calibrating an antenna array comprising the steps of:
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generating a calibration signal from a coherent source as an input signal;
selectively injecting said input signal into a receive channel;
obtaining a first set of I/Q signals; and
calculating a reception data channel offset based on said first set of I/Q signals. - View Dependent Claims (9, 10, 11, 12, 13, 14)
providing a test signal in a transmission data channel;
generating a transmission signal from said transmission data channel;
selectively providing said transmission signal as said input signal when said calibration signal is not provided as said input signal;
generating a second set of I/Q signals based on said transmission signal provided as said input signal; and
calculating a loop back offset based on said second set of I/Q signals.
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11. The method of calibrating an antenna array of claim 10, further comprising the step of calculating transmission data channel offset is calculated according to the equation:
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12. The method of calibrating an antenna array of claim 11, further comprising the step of calculating a modification vector according to the equation:
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13. The method of calibrating an antenna array of claim 12, further comprising the step of calculating a transmission beamforming vector according to the equation:
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14. The method of calibrating an antenna array of claim 10, wherein said transmission data channel comprises a plurality of transmission data channels, the method further comprising the step of simultaneously injecting each channel of said plurality of transmission data channels with a test signal when said transmission signal is selectively provided as said input signal.
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15. An antenna array apparatus comprising:
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an antenna array which transmits and receives signals;
a receiving unit which obtains reception data channels from received signals;
a transmission unit which generates a transmission signal from transmission data channels;
a calibration signal generating unit which generates a calibration signal from a coherent source;
a calibration signal injecting unit which is operable to selectively inject said calibration signal as an input signal into said receiving unit;
a reception data channel unit which receives said reception data channels from said receiving unit and generates a first set of I/Q signals; and
a controller which controls said calibration signal injecting unit to selectively insert said calibration signal as said input signal, and receives said first set of I/Q signals from said reception channel unit, wherein said controller calculates a reception data channel offset based on said first set of I/Q signals. - View Dependent Claims (16, 17)
a transmission data channel unit which includes a transmission data channel, said transmission data channel being provided with a test signal; and
a loop back unit which selectively provides said transmission signal as said input signal, wherein said controller controls said loop back unit to selectively provide said transmission signal as said input signal, said reception data channel unit generates a second set of I/Q signals based on said transmission signal provided as said input signal, and provides said second set of I/Q signals to said controller, and said controller calculates a loop back offset based on said second set of I/Q signals.
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Specification