JP2001268151A - Predistortion compensating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a predistortion compensating device capable of easily preparing compensation data. SOLUTION: An amplifier parameter storage part 104 stores a parameter characterizing the input/output characteristics of an amplifier 111. A compensation data operating part 105 prepares the compensation data by operation using the parameter stored in the amplifier parameter storage part 104. A power calculating part 103 calculates power while using I and Q signals and outputs an address in a compensation data table 106 corresponding to the calculated power value to the compensation data table 106. The compensation data table 106 outputs the compensation data corresponding to the address sent from the power calculating part 103 to a complex multiplication part 107. The complex multiplication part 107 multiplies the compensation data from the compensation data table 106 to the I and Q signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a predistortion distortion compensator applied to a mobile communication system using a digital modulation system.

[0002]

2. Description of the Related Art Conventionally, in a mobile communication system using a digital modulation system, a high-efficiency amplifier is used in a transmission system in order to save power of a transmission device as a wireless terminal. However, a high-efficiency amplifier is likely to generate nonlinear distortion. As a result of the distortion generated by the amplifier, the transmission spectrum of the transmission device is widened, so that the transmission device has an adverse effect of increasing interference with an adjacent channel.

[0003] Therefore, a distortion compensating device for achieving both high efficiency and low distortion is applied to a transmitting device. As one of the distortion compensators, there is a pre-distortion distortion compensator. Since the pre-distortion distortion compensating apparatus performs the distortion compensating processing by baseband digital signal processing, it is advantageous in stabilizing the performance and reducing the size of the transmitting apparatus.

FIG. 4 is a block diagram showing a configuration of a transmission device provided with a conventional pre-distortion distortion compensating device. 4, the I signal and the Q signal input from the I signal input terminal 11 and the Q signal input terminal 12, respectively, are output to the power calculation unit 13 and the complex multiplication unit 15.

[0005] After calculating the power using the I signal and the Q signal, the power calculator 13 outputs the address of the compensation data table 14 corresponding to the calculated power to the compensation data table 14. Compensation data table 14
Then, the compensation data at the address output by the power calculation unit 13 is output to the complex multiplication unit 15.
Note that the compensation data table 14 stores the inverse characteristics of the input / output characteristics of the amplifier 21 to be compensated as compensation data necessary for performing distortion compensation on the I signal and the Q signal.

The complex multiplier 15 multiplies the I signal and the Q signal by the compensation data from the compensation data table. I multiplied by the compensation data by the complex multiplier 15
The signal and the Q signal are converted into analog signals by the D / A converter 16 and the D / A converter 17, respectively, and then quadrature modulated by the quadrature modulator 18. The signal after the quadrature modulation is amplified by the amplifier 19 and then output from the output terminal 20. As described above, the amplifier 19
Output a signal on which distortion compensation has been performed.

[0007]

However, in the conventional pre-distortion distortion compensating apparatus, when the compensation data table is created, many compensations are required to obtain the inverse characteristics of the input / output characteristics of the amplifier to be compensated. Since the input / output characteristics of the amplifier must be measured at the point, there is a problem that much labor is required.

[0008] The present invention has been made in view of the above points, and an object of the present invention is to provide a pre-distortion distortion compensating apparatus capable of easily creating compensation data.

[0009]

A predistortion distortion compensating apparatus according to the present invention performs distortion compensation processing on a baseband signal to generate a transmission signal, and amplifies the generated transmission signal. Amplifying means; and compensation data creating means for creating compensation data using at least one element characterizing input / output characteristics of the amplifying means;
Wherein the distortion compensating means performs distortion compensation processing by multiplying the baseband signal by data corresponding to the power value of the baseband signal among the compensation data.

According to this configuration, compensation data can be easily created by calculation using parameters characterizing the input / output characteristics of the amplifier. Thus, it is possible to provide a pre-distortion distortion compensator capable of easily creating compensation data.

[0011] In the predistortion distortion compensating apparatus according to the present invention, the compensation data creating means calculates the input / output characteristics of the amplifying means using at least one element;
Inverse characteristic calculating means for calculating an inverse characteristic to the input / output characteristic of the amplifying means using the calculated input / output characteristic, and a configuration for creating compensation data using the calculated inverse characteristic.

According to this configuration, after the input / output characteristics are obtained by the calculation using the parameters characterizing the input / output characteristics of the amplifying means, the inverse characteristic is calculated from the obtained input / output characteristics. Can be created. Thus, it is possible to provide a pre-distortion distortion compensator capable of easily creating compensation data.

[0013] In the predistortion distortion compensating apparatus of the present invention, the compensation data generating means includes a storing means for storing at least one element characterizing the input / output characteristics of the amplifying means for each operating condition of the amplifying means. A configuration is employed in which compensation data is created by using an element that most closely matches the input / output characteristics of the amplifying means among the elements stored by the storage means.

According to this configuration, even when the input / output characteristics of the amplifying means change due to a change in the operating conditions, the input / output characteristics of the amplifying means under the above operating conditions are the most important among the parameters prepared for each operating condition. Since the matched parameters are used for the distortion compensation processing, the effect of the distortion compensation processing can be enhanced.

[0015] A communication terminal apparatus according to the present invention includes any one of the predistortion distortion compensating apparatuses described above.

According to the present invention, it is possible to provide a communication terminal device which realizes good communication by mounting a pre-distortion distortion compensator capable of easily creating compensation data.

[0017] A base station apparatus according to the present invention includes any one of the predistortion distortion compensating apparatuses described above.

According to the present invention, it is possible to provide a base station apparatus which realizes good communication by mounting a pre-distortion distortion compensator capable of easily creating compensation data.

According to the predistortion distortion compensation method of the present invention, a distortion compensation step of generating a transmission signal by performing a distortion compensation process on a baseband signal; an amplification step of amplifying the generated transmission signal; And compensating data using at least one element characterizing the input / output characteristics of the means. The distortion compensating step corresponds to a power value of the baseband signal in the compensation data. A method of performing distortion compensation processing by multiplying data by the baseband signal is employed.

According to this method, compensation data can be easily created by calculation using parameters characterizing input / output characteristics in the amplification step. This allows
A predistortion distortion compensating device capable of easily creating compensation data can be provided.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The gist of the present invention is that compensation data necessary for distortion compensation processing is obtained by calculation using parameters characterizing the input / output characteristics of the amplification means.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a block diagram showing a configuration of a transmitting apparatus provided with a pre-distortion distortion compensating apparatus according to Embodiment 1 of the present invention. In FIG. 1, an I component (hereinafter, referred to as “I signal”) and a Q component (hereinafter, referred to as “Q signal”) of a baseband signal are input to an input terminal 101 and an input terminal 102, respectively.

Power calculation section 103 calculates power using the I signal and Q signal input from input terminal 101 and input terminal 102, respectively. Further, the power calculation unit 103 calculates an address in the compensation data table 106 corresponding to the calculated power value.
Output to

The amplifier parameter storage section 104 stores parameters (elements) characterizing the input / output characteristics of the amplifier 111 to be compensated. The parameters include the slope of the input / output characteristics, the value of the input signal at a point where the input / output characteristics become non-linear, and the gain when the input / output characteristics are linear in the section where the input / output characteristics are non-linear. In comparison, the value of the output signal when the gain is reduced by a predetermined value (for example, 1 dB compression) or the like is used. Other parameters may be used as long as they characterize the input / output characteristics of the amplifier 111.

The compensation data calculation section 105 creates compensation data by calculation using the parameters stored in the amplifier parameter storage section 104. That is, the compensation data calculation unit 105 first uses the parameters stored in the above-described amplifier parameter storage unit 104 to
Is calculated, and based on the calculated input / output characteristics, an inverse characteristic of the input / output characteristics is created. The inverse characteristic of the input / output characteristic is sent to the compensation data table as compensation data.

In the conventional method, the input / output characteristics of the amplifier must be measured at many points in order to obtain compensation data. According to the present embodiment, however, the compensation data is calculated by using several parameters. It is possible to get

The compensation data table 106 stores the compensation data created by the compensation data calculation unit 105, and outputs compensation data corresponding to the address sent from the power calculation unit 103 to the complex multiplication unit 107.

The complex multiplication unit 107 multiplies the I signal and the Q signal by compensation data from the compensation data table 106. The D / A converter 108 and the D / A converter 109 respectively convert the I signal and the Q signal after the compensation data multiplication into analog signals.

The quadrature modulating section 110 includes the D / A converter 1
08 and the analog signal from the D / A converter 109 are subjected to quadrature modulation. A transmission signal is obtained by this quadrature modulation. Amplifier 111 amplifies the transmission signal from quadrature modulation section 110 and outputs the amplified signal to output terminal 112. As described above, a signal subjected to distortion compensation is output from the amplifier 111.

As described above, according to the present embodiment, in order to generate compensation data necessary for the distortion compensation processing, after measuring the input / output characteristics of the amplifier to be compensated, the inverse characteristic is obtained from the measured input / output characteristics. Rather than calculating the compensation data, the inverse characteristics are calculated from the acquired input / output characteristics after the above-mentioned input / output characteristics are obtained by calculation using parameters characterizing the input / output characteristics of the amplifier to be compensated. Can be created. Thus, it is possible to provide a pre-distortion distortion compensator capable of easily creating compensation data.

In the present embodiment, the parameters stored in the amplifier parameters are used for the amplifier 111.
After calculating the input / output characteristics of the input / output characteristics, the case where the inverse characteristics (compensation data) of the input / output characteristics are calculated has been described. However, the present invention is not limited to this. Compensation data) is also applicable.

(Second Embodiment) In a second embodiment, a case will be described in which a change in input / output characteristics of an amplifier is handled. Even in the case of the same amplifier, there may be a case where the input / output characteristics of the amplifier vary in manufacturing. In this case, the distortion compensation processing is performed using compensation data based on input / output characteristics different from those of the amplifier actually used. For this reason, even though the distortion compensation processing has been performed, this amplifier may generate nonlinear distortion. That is, the effect of the distortion compensation processing may be degraded.

Therefore, in this embodiment, a plurality of amplifier parameter storage units are prepared. Hereinafter, a transmitting apparatus including the predistortion distortion compensating apparatus according to the present embodiment will be described with reference to FIG. FIG. 2 is a block diagram showing a transmitting apparatus including a pre-distortion distortion compensating apparatus according to Embodiment 2 of the present invention. In addition, about the structure similar to Embodiment 1 (FIG. 1) in FIG.
The same reference numerals are given, and the detailed description is omitted.

In FIG. 2, an amplifier parameter storage 2
02 to the amplifier parameter storage unit 204 are the same as the amplifier parameter storage unit 104 in the first embodiment described above in that parameters that characterize the input / output characteristics of the amplifier to be compensated are stored. However, the amplifier parameter storage units 202 to 204
The mutually different parameters are stored so as to include manufacturing variations of the input / output characteristics of the amplifier 111.

The switch 201 receives the parameters from the amplifier parameter storage unit 202 to the amplifier parameter storage unit 204.
The parameter most matching the input / output characteristic of No. 1 is output to the compensation data calculation unit 105.

As described above, according to the present embodiment, even when the input / output characteristics of the amplifier to be compensated have manufacturing variations, etc., among the parameters stored in the plurality of amplifier parameter storage units prepared, Since the parameter most matched to the characteristics of the amplifier to be compensated is used for the distortion compensation processing, it is possible to suppress the effect deterioration due to the distortion compensation processing.

In the present embodiment, a description will be given of a case where a plurality of amplifier parameter storage sections for storing mutually different parameters are prepared so as to include manufacturing variations in the input / output characteristics of the amplifier to be compensated. However, the present invention is not limited to this, and can be applied to a case where a plurality of amplifier parameter storage units that store parameters characterizing the input / output characteristics of a plurality of types of compensation target amplifiers are prepared. Accordingly, even when the compensation target amplifier is changed, the distortion compensation processing according to the changed compensation target amplifier can be reliably performed.

(Embodiment 3) In Embodiment 3, a case will be described in which the input / output characteristics of the amplifier to be compensated change due to a change in the operating conditions of the transmitting apparatus body. The input / output characteristics of the amplifier to be compensated may change in accordance with the operating conditions of the transmitting device main body, that is, for example, changes in conditions such as the temperature around the transmitting device main body and the power supply voltage in the transmitting device. In this case, depending on the above conditions, the effect of the distortion compensation processing may be deteriorated.

Therefore, in the present embodiment, a plurality of amplifier parameter storage units are prepared, and among the parameters stored in the amplifier parameter storage unit, the parameters used for the distortion compensation processing are optimized for the operating conditions of the transmitting apparatus main body. Parameters. Hereinafter, a transmitting apparatus including the predistortion distortion compensating apparatus according to the present embodiment will be described with reference to FIG.

FIG. 3 is a block diagram showing a configuration of a transmitting apparatus including a pre-distortion distortion compensating apparatus according to Embodiment 3 of the present invention. Note that the same reference numerals as in FIG. 2 denote the same components in FIG. 3 as those in the second embodiment, and a detailed description thereof will be omitted.

In FIG. 3, an amplifier parameter storage 3
03 to the amplifier parameter storage unit 305 are the same as the amplifier parameter storage unit in each of the above-described embodiments in that the parameters that characterize the input / output characteristics of the amplifier to be compensated are stored. However, the amplifier parameter storage units 303 to 305 store parameters characterizing the input / output characteristics of the amplifier under various operating conditions.

The switching unit 306 receives the parameters from the amplifier parameter storage unit 303 to the amplifier parameter storage unit 305 and, among the above parameters, the parameter selected by the switching control unit 302 described later to the compensation data calculation unit 105. Output.

The switching control unit 302 inputs n types of operation determination signals from the operation determination signal input terminals 301-1 to 301-n. The operation determination signal is a signal indicating an operation condition of the apparatus main body, that is, a signal indicating a condition which affects input / output characteristics of the amplifier to be compensated. Specific examples of the operation determination signal include a temperature around the transmission device main body, a voltage value of a power supply provided in the transmission device, and the like.

Further, the switching control section 302 stores the amplifier parameter storage section 3 based on the input operation determination signal.
03 to select the optimum parameter from the parameters stored by the amplifier parameter storage unit 305 and output the selection result to the switch 306.

As described above, according to the present embodiment, even when the input / output characteristics of the amplifier to be compensated change due to a change in the operating conditions of the transmitter, a plurality of amplifier parameter storage units are stored. Among the parameters, the parameter most matching the input / output characteristics of the amplifier to be compensated under the above operating conditions is used for the distortion compensation processing, so that the effect of the distortion compensation processing can be enhanced.

Conventionally, a method has been adopted in which a plurality of compensation data tables are prepared and one of the plurality of compensation data tables to be used is switched in accordance with the operating conditions. Since only one compensation data table is required, the storage capacity of the compensation data table can be reduced as compared with the conventional method.

The pre-distortion distortion compensating device according to the above-described embodiment can be mounted on a communication terminal device or a base station device in mobile communication.

[0049]

As described above, according to the present invention,
Since the compensation data required for the distortion compensation processing is obtained by calculation using the parameters characterizing the input / output characteristics of the amplifying means, it is possible to provide a pre-distortion distortion compensator capable of easily creating compensation data.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a transmitting apparatus including a predistortion distortion compensating apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a block diagram showing a transmission device including a pre-distortion distortion compensating device according to Embodiment 2 of the present invention.

FIG. 3 is a block diagram showing a configuration of a transmitting apparatus including a predistortion distortion compensating apparatus according to Embodiment 3 of the present invention.

FIG. 4 is a block diagram showing a configuration of a transmission device including a conventional predistortion distortion compensating device.

[Explanation of symbols]

103 Power calculation unit 104, 202 to 204, 303 to 305 Amplifier parameter storage unit 105 Compensation data operation unit 106 Compensation data table 107 Complex multiplication unit 111 Amplifier 201, 306 Switch 302 Switching control unit

Continued on front page F-term (reference) 5J090 AA01 AA41 CA00 CA21 FA18 GN03 HA38 KA00 KA33 KA34 KA53 SA14 5J091 AA01 AA41 CA00 CA21 FA18 HA38 KA00 KA33 KA34 KA53 SA14 5K004 AA01 AA05 BA02 BB02 BC01 FE05 FF10

Claims (6)

[Claims] 1. A distortion compensation means for generating a transmission signal by performing a distortion compensation process on a baseband signal; an amplification means for amplifying the generated transmission signal; and at least an input / output characteristic of the amplification means. Compensation data creating means for creating compensation data using one element, wherein the distortion compensation means converts data corresponding to the power value of the baseband signal in the compensation data to the baseband signal. A pre-distortion distortion compensator that performs distortion compensation processing by multiplying. 2. A compensation data creation means for calculating an input / output characteristic of an amplification means using at least one element, and an inverse of the input / output characteristic of the amplification means using the calculated input / output characteristic. The predistortion distortion compensating apparatus according to claim 1, further comprising: an inverse characteristic calculating unit configured to calculate the characteristic, wherein the compensation data is created using the calculated inverse characteristic. 3. The compensation data creation means includes storage means for storing at least one element characterizing the input / output characteristics of the amplification means for each operating condition of the amplification means, and stores the at least one of the elements stored by the storage means. 3. The pre-distortion distortion compensator according to claim 1, wherein the compensation data is created by using an element most matching the input / output characteristics of the amplifying unit. 4. A communication terminal device comprising the pre-distortion distortion compensating device according to claim 1. 5. A base station apparatus comprising the pre-distortion distortion compensating device according to claim 1. Description: 6. A distortion compensation step of generating a transmission signal by performing a distortion compensation process on a baseband signal, an amplification step of amplifying the generated transmission signal, and at least an input / output characteristic of the amplifying means. A compensating data creating step of creating compensation data using one element, wherein the distortion compensating step converts data corresponding to the power value of the baseband signal in the compensation data into the baseband signal. A predistortion distortion compensation method, wherein a distortion compensation process is performed by multiplication.