High-frequency signal predistortion device and nonlinear distortion correcting device for power amplifier
A high-frequency signal predistortion device includes a high-frequency signal estimator, a predistortion estimator, and a predistorter. The high-frequency signal estimator is configured to determine non-linear distortion characteristics of high-frequency signals transmitted by antennas. The predistortion estimator is coupled to the high-frequency signal estimator. The predistortion estimator is configured to determine a predistortion coefficient based on the non-linear distortion characteristics. The predistorter is coupled to the predistortion estimator. The predistorter is configured to distort a base signal of the high-frequency signals based on the predistortion coefficient.
1. A frequency signal predistortion device, comprising:
a frequency signal estimator configured to sequentially determine non-linear distortion characteristics of frequency signals transmitted by antennas in a multiple-input multiple-output (MIMO) scheme;
a predistortion estimator coupled to the frequency signal estimator, the predistortion estimator configured to determine a predistortion coefficient based on the non-linear distortion characteristics; and
a predistorter coupled to the predistortion estimator, the predistorter configured to distort a base signal of the frequency signals based on the predistortion coefficient,
wherein the frequency signal estimator comprises training sequence blocks configured to:
determine the non-linear distortion characteristics using a least squares method,
sequentially receive the frequency signals through a single input path to be applied to the training sequence blocks in a time sharing method,
determine a cost function of a least squares method with respect to each of the training sequence blocks, and
determine a least-squares determined coefficient reducing the cost function of the least squares method.
2. The frequency signal predistortion device of claim 1 , further comprising:
power amplifiers configured to amplify and output the frequency signals,
wherein the frequency signal estimator determines non-linear distortion characteristics of the power amplifiers.
3. The frequency signal predistortion device of claim 2 , further comprising:
a frequency chain coupled between the predistorter and the power amplifiers, the frequency chain performing digital-to-analog conversion operations and frequency modulation operations on the base signal; and
a feedback detector converting signals output by the power amplifiers into a baseband signal, performing analog-to-digital conversion operations on the baseband signal, and transmitting the baseband signal to the frequency signal estimator.
4. The frequency signal predistortion device of claim 1 , further comprising:
a beamformer configured to shift a phase of the base signal predistorted by the predistorter based on a beamforming vector.
5. The frequency signal predistortion device of claim 4 , wherein the predistortion coefficient is a value for reducing a difference between a value obtained by multiplying power of the base signal by the beamforming vector, and a value based on the non-linear distortion characteristics.
6. The frequency signal predistortion device of claim 1 , wherein the predistortion estimator determines the predistortion coefficient on the basis of a gradient vector based on the non-linear distortion characteristics and a correlation matrix based on power of the base signal.
7. A frequency signal predistortion device, comprising:
a frequency signal estimator configured to sequentially determine non-linear distortion characteristics of frequency signals transmitted by antennas in a multiple-input multiple-output (MIMO) scheme;
a predistortion estimator coupled to the frequency signal estimator, the predistortion estimator configured to determine a predistortion coefficient based on the non-linear distortion characteristics; and
a predistorter coupled to the predistortion estimator, the predistorter configured to distort a base signal of the frequency signals based on the predistortion coefficient,
wherein the predistortion estimator determines the predistortion coefficient on the basis of a gradient vector based on the non-linear distortion characteristics and a correlation matrix based on power of the base signal, and
wherein the predistortion estimator updates a value obtained by subtracting a value based on multiplication of the gradient vector and the correlation matrix, from an N predistortion coefficient used for predistortion in an N step, by predistortion in an N+1 step, where N is a natural number.
8. A nonlinear distortion correcting device for power amplifier, comprising:
a predistortion processor configured to distort a base signal based on an N predistortion coefficient, convert the base signal into frequency signals, and transmit the frequency signals to power amplifiers in a multiple-input multiple-output (MIMO) scheme, respectively; and
a feedback signal processor configured to determine non-linear distortion characteristics of the power amplifiers, determine N+1 predistortion coefficient, and update the N predistortion coefficient to the N+1 predistortion coefficient, where N is a natural number,
wherein the power amplifiers are provided as a first power amplifier, a second power amplifier, a third power amplifier, and a fourth power amplifier, and
wherein the predistortion processor includes:
a multiple-input multiple-output (MIMO) precoder generating the base signal using the MIMO scheme;
a predistorter predistorting the base signal based on an N predistortion coefficient;
a first beamformer shifting a phase of a signal predistorted by the predistorter based on a beamforming vector to transmit the signal to the first power amplifier and the second power amplifier; and
a second beamformer shifting a phase of a signal predistorted by the predistorter based on a beamforming vector to transmit the signal to the third power amplifier and the fourth power amplifier.