JPH10150394A - Nonlinear distortion compensation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means that compensates nonlinear distortion caused in an amplifier of a transmission system without using a storage table to store compensation coefficients which compensate a nonlinear distortion component in communication equipment for a radio communication system. SOLUTION: By using an amplitude value of a transmission orthogonal base band signal obtained with a power calculation part 102 a compensation coefficient calculation section 104 calculates nonlinear distortion compensation data according to an approximate formula and a nonlinear distortion compensation part 106 using the data conducts nonlinear distortion compensation so as to compensate nonlinear distortion caused in an amplifier of a transmission system without using a storage table and then the nonlinear distortion compensation device having a high distortion reduction effect is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-linear distortion compensator for compensating for non-linear distortion generated in a transmission system, which is used in a communication device of a radio communication system.

[0002]

2. Description of the Related Art Conventionally, as a method of compensating for nonlinear distortion of a transmission system, a digital filter having a ROM (Read Only Memory) is provided, and distortion for compensating for nonlinear distortion generated in an amplifier is previously corrected by a digital filter. There is a way to compensate by giving.

FIG. 5 shows a block configuration of a conventional nonlinear distortion compensator. 501 is a digital signal, 502 is RO
M is a digital filter added, 503 is a modulation unit, 5
Reference numeral 04 denotes a transmission unit, and reference numeral 505 denotes a high-frequency power amplifier.

[0004] The digital filter 502 to which the digital signal 501 is input gives distortion to the digital signal 501 for compensating for a nonlinear distortion component generated in the high-frequency power amplifier 505 by using distortion information stored in advance in the ROM. . Digital signal 501 given distortion for compensation
Are D / A-converted and modulated by the modulation unit 503, and input to the high-frequency power amplifier 505 via the transmission unit 504.
In the high-frequency power amplifier 505, since the input digital signal is distortion-compensated in advance, the high-frequency power amplifier 50
5 is canceled by the compensation distortion.

Japanese Patent Application Laid-Open No. 4-290321 discloses a method of controlling the operation of a digital filter by feeding back the output of a high-frequency power amplifier to a digital filter.

[0006]

In such a nonlinear distortion compensating apparatus, a storage circuit such as a ROM for storing a compensation coefficient for compensating the nonlinear distortion component is required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a means for compensating for non-linear distortion generated in a transmission system amplifier without using a storage table realized by a ROM or the like in a communication device of a wireless communication system. .

[0008]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention obtains the power of a signal from an input quadrature baseband signal, and calculates a distortion compensation coefficient by an approximate expression for distortion compensation using the value as a parameter. Calculate and perform nonlinear distortion compensation using it, and update the coefficients of the approximation using the error between the orthogonal signal and the orthogonal baseband signal obtained by demodulating the output to which the modulated output is distributed. It is configured as follows.

As a result, a non-linear distortion compensating apparatus for compensating for non-linear distortion generated in a transmission system amplifier without using a storage table realized by a ROM or the like can be obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is provided in a communication device of a wireless communication system, and includes a power calculation unit for calculating a power value of a transmission orthogonal baseband signal;
A compensation coefficient calculation unit that calculates a nonlinear distortion compensation coefficient by an approximate expression set in advance using the power value, and a nonlinear distortion compensation unit that performs nonlinear distortion compensation of the transmission orthogonal baseband signal using the nonlinear distortion compensation coefficient. And has an operation of compensating for nonlinear distortion generated in the transmission system amplifier with a small storage capacity.

According to a second aspect of the present invention, there is provided a communication device of a wireless communication system, comprising: a power calculator for calculating a power value of a transmission quadrature baseband signal; and an approximate expression preset using the power value. A compensation coefficient calculation unit that calculates an amplitude distortion compensation coefficient, an orthogonal modulation unit that orthogonally modulates the transmission orthogonal baseband signal, and an amplitude distortion compensation unit that performs amplitude distortion compensation on a modulation signal using the amplitude distortion compensation coefficient. The nonlinear distortion compensator provided has an operation of compensating for amplitude distortion generated in a transmission system amplifier with a simple operation and a small storage capacity.

According to a third aspect of the present invention, there is provided a communication device of a wireless communication system, comprising: a power calculator for calculating a power value of a transmission orthogonal baseband signal; and an approximate expression preset using the power value. A compensation coefficient calculation unit that calculates an amplitude distortion compensation coefficient, an orthogonal modulation unit that orthogonally modulates the transmission orthogonal baseband signal, and an amplitude distortion compensation unit that performs amplitude distortion compensation on a modulation signal using the amplitude distortion compensation coefficient. An amplifier for amplifying the modulated signal; a distributor for distributing the output of the amplifier; a quadrature detector for inputting one of the outputs of the distributor for quadrature detection; and an A / A for digitally converting the output of the quadrature detector. D converter, the power value and the A / D
A coefficient updating unit that calculates an error by comparing the output of the converter with the output of the converter, and updates the value of the coefficient of the approximation formula based on the error. By reducing the error of the distortion compensation data by using a feedback loop, there is an effect that highly accurate amplitude distortion compensation is performed.

According to a fourth aspect of the present invention, there is provided a communication device of a wireless communication system, wherein the power calculating unit calculates a power value of a transmission quadrature baseband signal, and a non-linear distortion compensation preset using the power value. A table reference unit that outputs a distortion compensation coefficient from a table, a correction coefficient calculation unit that receives the power value, and calculates a correction value of the distortion compensation coefficient using an approximate expression, and calculates the distortion compensation coefficient and the correction coefficient. A nonlinear distortion compensator that performs nonlinear distortion compensation of the transmission quadrature baseband signal using a quadrature modulator that orthogonally modulates an output of the nonlinear distortion compensator; an amplifier that amplifies the output of the quadrature modulator; and the amplifier , An orthogonal detector that receives one of the outputs of the distributor and performs orthogonal detection, and an A / D converter that converts the output of the orthogonal detector into a digital signal.
A nonlinear conversion unit comprising: a D conversion unit; and a coefficient updating unit that compares an output of the A / D conversion unit with the transmission quadrature baseband signal to calculate an error and updates a coefficient of the approximation expression based on the error. The distortion compensating device has a function of performing highly accurate nonlinear distortion compensation by reducing an error of nonlinear distortion compensation data calculated by a table reference unit and a correction data calculation unit using a feedback loop.

An embodiment of the present invention will be described below with reference to FIGS. (Embodiment 1) FIG. 1 is a block diagram of a main part of a nonlinear distortion compensator according to the present embodiment. In FIG. 1, reference numeral 101 denotes a transmission digital orthogonal baseband signal;
102 is a power calculator, 103 is an amplitude value calculated by the power calculator 102, 104 is a compensation coefficient calculator for nonlinear distortion compensation, 105 is orthogonalized nonlinear distortion compensation data, 106
Is a nonlinear distortion compensator, 107 is a non-linear distortion-compensated quadrature baseband signal, 108 is a D / A converter, 109 is an analog quadrature baseband signal, 110 is a low-pass filter for band limitation, and 111 is band-limited. Analog quadrature baseband signal, 112 is a quadrature modulator, 113 is a modulation signal, 114 is a transmission system amplifier, and 115 is an amplified transmission modulation signal.

The operation of the transmitting apparatus configured as described above will be described with reference to FIG. First, the power calculator 102 calculates the amplitude value 103 of the transmission signal from the transmission digital orthogonal baseband signal 101.
Next, using the calculated transmission signal amplitude value 103 as an input value, the compensation coefficient calculator 104 approximates the nonlinear distortion compensation data 105 obtained by orthogonalizing the nonlinear distortion compensation data having the inverse characteristic of the nonlinear distortion characteristic of the transmission system. Calculate using the formula.

The nonlinear distortion compensator 106 performs a complex product of the transmission digital orthogonal baseband signal 101 and the orthogonalized nonlinear distortion compensation data 105, and outputs a nonlinear distortion-compensated orthogonal baseband signal 107. The non-linear distortion-compensated orthogonal baseband signal 107 is converted to a D / A converter
In step 8, the signal is converted into an analog signal, and the band is limited by the low-pass filter 110 to obtain an analog quadrature baseband signal 111. Then, after performing quadrature modulation by a quadrature modulator 112 to generate a modulated signal 113, a transmission system amplifier 114
Then, the transmission modulation signal 115 is output after being amplified to a required size.

(Embodiment 2) FIG. 2 is a block diagram showing a main part of a nonlinear distortion compensator according to this embodiment. 2, reference numeral 201 denotes a transmission digital orthogonal baseband signal, 202 denotes a power calculation unit, 203 denotes an amplitude value calculated by the power calculation unit 202, 204 denotes a compensation coefficient calculation unit for amplitude distortion compensation, 205 denotes amplitude distortion compensation data, 206 is a D / A converter, 207 is an analog quadrature baseband signal, 208 is a low-pass filter for band limitation, 209 is a band-limited analog quadrature baseband signal, 210
Is a quadrature modulator, 211 is a modulation signal, 212 is a gain control amplifier for amplitude distortion compensation, 213 is a modulation signal with amplitude distortion compensation, 214 is a transmission system amplifier, and 215 is an amplified transmission modulation signal.

The operation of the transmitting apparatus configured as described above will be described with reference to FIG. First, the power calculator 202 calculates the amplitude value 203 of the transmission signal from the transmission digital orthogonal baseband signal 201. Next, using the calculated transmission signal amplitude value 203 as an input value,
Compensation coefficient calculation section 204 calculates amplitude distortion compensation data 205 having an inverse characteristic of the amplitude distortion characteristic of the transmission system using an approximate expression.

On the other hand, the transmission digital quadrature baseband signal 201 is converted into an analog signal by the D / A converter 206, and the band is limited by the low-pass filter 208.
An analog quadrature baseband signal 209 is obtained. And
After performing quadrature modulation by the quadrature modulator 210 to obtain a modulated signal 211, the gain control amplifier 212 for amplitude distortion compensation performs amplitude distortion compensation based on the amplitude distortion compensation data 205 to obtain a modulated signal 213 with amplitude distortion compensation. . Finally, the amplifier 214
And amplifies it to a required size to output a transmission modulation signal 215.

(Embodiment 3) FIG. 3 is a block diagram showing a main part of a nonlinear distortion compensator according to this embodiment. 3, reference numeral 301 denotes a transmission digital orthogonal baseband signal, 302 denotes a power calculator, 303 denotes an amplitude value calculated by the power calculator 302, 304 denotes a compensation coefficient calculator for amplitude distortion compensation, 305 denotes amplitude distortion compensation data, 306 is a D / A converter, 307 is an analog quadrature baseband signal, 308 is a low-pass filter for band limitation, 309 is a band-limited analog quadrature baseband signal, 310
Is a quadrature modulator, 311 is a modulation signal, 312 is a gain control amplifier for amplitude distortion compensation, 313 is a modulation signal with amplitude distortion compensation, 314 is a transmission system amplifier, 315 is an amplified transmission modulation signal, and 316 is directionality. A coupler 317 is a distributed transmission modulation signal, 318 is a quadrature detector, 319 is a quadrature detected quadrature baseband signal, 320 is a low-pass filter for band limitation, 321 is a band-limited quadrature baseband signal, Reference numeral 322 denotes an A / D converter, 323 denotes a digital orthogonal baseband signal, 324 denotes a coefficient updating unit, and 325 denotes coefficient data of an approximate expression for calculating a compensation coefficient.

The operation of the transmitting apparatus configured as described above will be described with reference to FIG. First, a power calculator 302 calculates an amplitude value 303 of a transmission signal from a transmission digital orthogonal baseband signal 301. Next, using the calculated transmission signal amplitude value 303 as an input value,
The compensation coefficient calculator 304 calculates the amplitude distortion compensation data 305 having the inverse characteristic of the amplitude distortion characteristic of the transmission system using an approximate expression.

On the other hand, the transmission digital quadrature baseband signal 301 is converted into an analog signal by the D / A converter 306, and the band is limited by the low-pass filter 308.
An analog quadrature baseband signal 309 is obtained. And
A quadrature modulator 310 performs quadrature modulation to obtain a modulated signal 311, and a gain control amplifier 312 for amplitude distortion compensation performs amplitude distortion compensation based on the amplitude distortion compensation data 305, and then modulates the amplitude signal 313. Get. Amplifier 314 amplifies the signal to a required size and outputs transmission modulation signal 315.
At this time, the transmission modulation signal 315 is distributed by the directional coupler 316.

The distributed transmission modulation signal 317 is subjected to quadrature detection by a quadrature detection unit 318, and a low-pass filter 3 for band limitation is used.
After passing through 20, the signal is converted into a digital signal by an A / D converter 322 to obtain a digital orthogonal baseband signal 323. The coefficient updating unit 324 updates the coefficient data 325 of the approximate expression so that the difference between the amplitude of the digital orthogonal baseband signal 323 and the amplitude value 303 of the transmission signal is minimized.

(Embodiment 4) FIG. 4 is a block diagram showing a main part of a nonlinear distortion compensator according to the present embodiment. 4, reference numeral 401 denotes a transmission digital orthogonal baseband signal, 402 denotes a power calculation unit, 403 denotes an amplitude value calculated by the power calculation unit 402, and 404 denotes a fixed compensation coefficient for nonlinear distortion compensation using the amplitude value 403. 405 is a fixed nonlinear distortion compensation coefficient that has been orthogonalized, 406 is a correction coefficient calculation unit that calculates a correction coefficient for nonlinear distortion compensation using the amplitude value 403, and 407 is an orthogonalized corrected nonlinear distortion compensation coefficient , 408 are non-linear distortion compensators, 40
9 is a quadrature baseband signal with nonlinear distortion compensation, 410
Is a D / A converter, 411 is an analog orthogonal baseband signal, 412 is a low-pass filter for band limitation, 413 is an analog orthogonal baseband signal with band limitation, 414
Is a quadrature modulator, 415 is a modulation signal, 416 is a transmission amplifier, 417 is an amplified transmission modulation signal, 418 is a directional coupler, 419 is a distributed transmission modulation signal, 420 is a quadrature detector, and 421 is a quadrature detector. The detected quadrature baseband signal 422 is a low-pass filter for band limitation, 423 is a quadrature baseband signal with band limitation, 424 is A / D
The conversion unit 425 is a digital orthogonal baseband signal,
Reference numeral 26 denotes a coefficient updating unit, and 427 denotes coefficient data of an approximate expression for calculating a correction coefficient.

The operation of the transmitting apparatus configured as described above will be described with reference to FIG. First, the power calculator 402 calculates the amplitude value 403 of the transmission signal from the transmission digital orthogonal baseband signal 401. Next, by referring to the fixed coefficient reference unit 404 with the calculated transmission signal amplitude value 403 as an address, the nonlinear distortion compensation data having the inverse characteristic of the nonlinear distortion characteristic of the transmission system calculated in advance is transformed into the nonlinear distortion compensation coefficient 405. At the same time, using the calculated transmission signal amplitude value 403 as an input value, the correction coefficient calculation unit 406 causes the nonlinear distortion compensation coefficient 405
Is calculated using an approximate expression. The nonlinear distortion compensator 408 performs a complex product of the transmission digital orthogonal baseband signal 401, the orthogonalized nonlinear distortion compensation data 405, and the correction coefficient 407, and outputs a nonlinear distortion-compensated orthogonal baseband signal 409. The orthogonal baseband signal 409 having been subjected to nonlinear distortion compensation is converted into a D / A
The signal is converted into an analog signal by the conversion unit 410, and the band is limited by the low-pass filter 412 to obtain an analog orthogonal baseband signal 413. Then, after performing quadrature modulation by a quadrature modulator 414 to generate a modulated signal 415, the signal is amplified to a required size by a transmission system amplifier 416 and then transmitted to a transmission modulation signal 417.
Is output. At this time, the transmission modulation signal 417 is distributed by the directional coupler 418.

The distributed transmission modulation signal 419 is subjected to quadrature detection by a quadrature detection section 420, and the low pass filter 4
After passing through 22, the signal is converted into a digital signal by an A / D converter 424 to obtain a digital orthogonal baseband signal 425. In the coefficient updating unit 426, the orthogonal baseband signal 401
And 425, the coefficient data 427 of the approximate expression for calculating the correction coefficient is updated.

[0027]

As described above, according to the present invention, in a communication device of a wireless communication system, a ROM for storing a compensation coefficient is provided.
By compensating for nonlinear distortion generated in the amplifier of the transmission system without using a storage table realized by, for example, the advantageous effect that highly accurate nonlinear distortion compensation having a large distortion reduction effect can be achieved. can get.

[Brief description of the drawings]

FIG. 1 is a block diagram of a main part of a nonlinear distortion compensator according to an embodiment of the present invention;

FIG. 2 is a block diagram of a main part of the nonlinear distortion compensator according to one embodiment of the present invention;

FIG. 3 is a block diagram of a main part of the nonlinear distortion compensator according to one embodiment of the present invention;

FIG. 4 is a block diagram of a main part of the nonlinear distortion compensator according to one embodiment of the present invention;

FIG. 5 is a block diagram showing a conventional nonlinear distortion compensator;

[Explanation of symbols]

 Reference Signs List 102 power calculation unit 104 compensation coefficient calculation unit 106 nonlinear distortion compensation unit 108 D / A conversion unit 110 low-pass filter 112 quadrature modulator 114 transmission system amplifier 202 power calculation unit 204 compensation coefficient calculation unit 206 D / A conversion unit 208 Low-pass filter 210 quadrature modulator 212 gain control amplifier for amplitude distortion compensation 214 transmission system amplifier 302 power calculation unit 304 compensation coefficient calculation unit 306 D / A conversion unit 308 low-pass filter 310 quadrature modulator 312 amplitude distortion compensation Gain control amplifier 314 transmission system amplifier 316 directional coupler 318 quadrature detector 320 low-pass filter 322 A / D converter 324 coefficient update unit 402 power calculation unit 404 fixed coefficient reference unit 406 correction coefficient calculation unit 408 nonlinear Distortion compensator 410 D / A converter 512 Low Pass filter 414 quadrature modulator 416 transmission system amplifier 418 a directional coupler 420 quadrature detection unit 422 lowpass filters 424 A / D conversion unit 426 coefficient updating unit

Continuation of the front page (72) Inventor Kimihide Mihozu 4-3-1 Tsunashima Higashi, Kohoku-ku, Yokohama-shi, Kanagawa Prefecture Matsushita Communication Industrial Co., Ltd.

Claims (4)

[Claims] 1. A wireless communication system comprising a communication device,
A power calculation unit that calculates a power value of the transmission orthogonal baseband signal, a compensation coefficient calculation unit that calculates a nonlinear distortion compensation coefficient by an approximate expression set in advance using the power value, and a compensation coefficient calculation unit that uses the nonlinear distortion compensation coefficient. A nonlinear distortion compensator comprising: a nonlinear distortion compensator that performs nonlinear distortion compensation on a transmission quadrature baseband signal. 2. A wireless communication system comprising a communication device,
A power calculation unit for calculating a power value of a transmission orthogonal baseband signal, a compensation coefficient calculation unit for calculating an amplitude distortion compensation coefficient using an approximate expression set in advance using the power value, and orthogonal modulation of the transmission orthogonal baseband signal. A non-linear distortion compensating device comprising: a quadrature modulator that performs amplitude distortion compensation; and an amplitude distortion compensator that performs amplitude distortion compensation on a modulated signal using the amplitude distortion compensation coefficient. 3. A communication device of a wireless communication system,
A power calculation unit for calculating a power value of a transmission orthogonal baseband signal, a compensation coefficient calculation unit for calculating an amplitude distortion compensation coefficient using an approximate expression set in advance using the power value, and orthogonal modulation of the transmission orthogonal baseband signal. A quadrature modulator, an amplitude distortion compensator for performing amplitude distortion compensation of a modulation signal using the amplitude distortion compensation coefficient, an amplifier for amplifying the modulation signal, a distributor for distributing an output of the amplifier, and the distributor A quadrature detection unit for inputting one of the outputs of
An A / D converter for digitally converting the output of the quadrature detector; comparing the power value with the output of the A / D converter to calculate an error; and calculating the coefficient of the approximate expression based on the error. A nonlinear distortion compensator comprising: a coefficient updating unit that updates a value. 4. A communication device of a wireless communication system,
A power calculator for calculating the power value of the transmission quadrature baseband signal, a table reference unit for outputting a distortion compensation coefficient from a non-linear distortion compensation table preset using the power value, and inputting the power value, an approximate expression A correction coefficient calculation unit that calculates a correction value of the distortion compensation coefficient using: a nonlinear distortion compensation unit that performs nonlinear distortion compensation of the transmission orthogonal baseband signal using the distortion compensation coefficient and the correction coefficient; A quadrature modulator for quadrature modulating the output of the distortion compensator,
An amplifier that amplifies the output of the quadrature modulator, a divider that distributes the output of the amplifier, a quadrature detector that receives one of the outputs of the divider and performs quadrature detection, and outputs the output of the quadrature detector digitally. An A / D converter for converting, and the A / D converter
A nonlinear distortion compensator comprising: a coefficient update unit that calculates an error by comparing an output of a conversion unit with the transmission quadrature baseband signal and updates a coefficient of the approximate expression based on the error.