WO2008035439A1

WO2008035439A1 - Distortion compensating circuit and method for controlling the same

Info

Publication number: WO2008035439A1
Application number: PCT/JP2006/318872
Authority: WO
Inventors: Tsutomu Hibino
Original assignee: Panasonic Corporation
Priority date: 2006-09-22
Filing date: 2006-09-22
Publication date: 2008-03-27

Abstract

A distortion compensating circuit capable of ensuring a distortion compensating performance even if the transmission power varies, while suppressing the increase in hardware of the distortion compensating circuit. In this circuit, an amplifier (310) has a nonlinear amplification characteristic. An inverse characteristic calculating part (330) compares a transport signal, which is an input signal to a distortion compensating part (370) with an output signal of the amplifier (310) to calculate an inverse characteristic of the amplifier (310). If the transmission power value of the transport signal exceeds a predetermined threshold value, a control part (340) writes data indicative of the inverse characteristic calculated by the inverse characteristic calculating part (330) into a storing part (360) to update a distortion compensating condition of the distortion compensating part (370). Otherwise, the control part (340) stops updating the distortion compensating condition of the distortion compensating part (370).

Description

Specification

Distortion compensation circuit and control method thereof

Technical field

The present invention relates to a distortion compensation circuit that amplifies a transmission signal with a circuit having nonlinear characteristics, and a control method therefor.

Background art

Conventionally, when amplifying the level of a transmission signal, there are a feed forward method and a predistortion method as a technique for compensating for signal distortion caused by nonlinearity of an amplifier.

[0003] The predistortion method is a method in which an input signal input to an amplifier is distorted in advance by a predistorter circuit having an inverse characteristic of the amplification characteristic of the amplifier and amplified. The pre-distortion method can perform distortion compensation processing with baseband digital signal processing, which is advantageous for performance stability and downsizing of the device.

[0004] The operation principle of the predistortion method in the wireless communication device will be described with reference to FIG.

As shown in FIG. 1A, a radio communication apparatus 100 of a predistortion system has a circuit configuration in which a predistorter circuit 3 is arranged in front of an amplifier 2 that amplifies an input signal and outputs it to the outside such as an antenna 1. take. With this circuit configuration, the predistorter circuit 3 of the wireless communication apparatus 100 multiplies the input transmission signal by a distortion compensation coefficient corresponding to the inverse characteristic of the amplification characteristic of the amplifier 2, and the signal distorted by this multiplication. Is output to amplifier 2. The amplifier 2 amplifies the input signal according to the amplification characteristic and outputs it to the antenna 1. In this way, a radio signal in which the nonlinear distortion of the amplifier 2 is compensated is output from the antenna 1 to the outside.

[0006] The principle of compensation for nonlinear distortion will be described with reference to FIGS. 1B to 1D. Now, let the signal level of the transmission signal be V and the input signal level V in the predistorter circuit 3

i i, PD

The output level is V, and the output signal level relative to the input signal level V in amplifier 2 is

o, PD ί, ΡΑ

If the bell is V, the input signal of level V is generated by the predistorter circuit 3 as shown in Figure 1B. Is converted to a level V output signal as shown in Fig. 1.

o, PD ί, ΡΑ

As shown in Fig. 1C, it is converted to a level V output signal. As a result, the final

ο, ΡΑ

In general, the relationship between the level V of the signal transmitted from the antenna 1 and the level V of the first transmission signal is linear as shown by the solid line in FIG. 1D, and nonlinear distortion is compensated.

As can be seen from FIG. 1D, in order to maintain high linearity in the signal amplification characteristic of the wireless communication device 100, the characteristic of the predistorter circuit 3 is exactly opposite to the amplification characteristic of the amplifier 2. Need to be set to have

[0008] For wireless transmission, the amplification characteristic of the amplifier 2 varies depending on the operating environment of the wireless communication apparatus 100 and the like. Therefore, when the operating environment of the wireless communication device 100 fluctuates and the amplification characteristic of the amplifier 2 fluctuates, the characteristic of the predistorter circuit 3 changes correspondingly and can follow the fluctuation of the amplification characteristic of the amplifier 2. Necessary. Therefore, conventionally, a part of the signal amplified by the amplifier 2 is fed back to the predistorter circuit 3 so that the characteristics of the predistorter circuit 3 also fluctuate with the fluctuation of the amplification characteristics of the amplifier 2. In some cases, an adaptive predistortion method that updates the distortion compensation coefficient is used (see, for example, Patent Document 1).

[0009] In general, the adaptive predistortion method is used! An inverse characteristic of the amplifier characteristic is obtained by comparing the input signal to the amplifier and the feedback signal after amplification. A corresponding distortion compensation coefficient is calculated. At this time, when the transmission power of the amplifier fluctuates dynamically, the inverse characteristic obtained by the transmission power changes, which causes a problem that the distortion compensation performance is greatly deteriorated.

[0010] In order to solve this problem, Patent Document 2 calculates and stores the reverse characteristics of the amplifier in association with the transmission power, and uses the reverse characteristics to be used based on the transmission power of the signal that is actually transmitted. A method of selecting and performing distortion compensation is shown. Specifically, a plurality of consecutive sections are set according to the magnitude of the transmission power of the transmission signal, and the inverse characteristics of the amplifier are calculated and stored in advance for each section, and transmitted during actual transmission. There is disclosed a method and apparatus for detecting a magnitude of power and selecting a reverse characteristic corresponding to the detected transmission power from reverse characteristics stored in advance and performing distortion compensation.

FIG. 2 illustrates the configuration and operation of a conventional distortion compensation circuit 200 disclosed in Patent Document 2. It is a figure for doing.

As shown in FIG. 2, the conventional distortion compensation circuit 200 is provided with a storage unit 220 that stores the inverse characteristic of the amplification characteristic of the amplifier 210. The storage unit 220 is divided into a plurality of storage areas 221 or 224, and a specific transmission power range is assigned to each of the areas 221 to 224.

The amplifier 210 outputs an output signal to the outside and outputs a part of the output signal to the receiving unit 230. Receiving section 230 receives the input signal and outputs it to inverse characteristic calculating section 240.

[0014] The inverse characteristic calculation unit 240 compares the transmission signal and the signal input from the reception unit 230, calculates the inverse characteristic of the amplification characteristic of the amplifier 210, and supplies the inverse characteristic data as a calculation result to the control unit 250. Output.

[0015] When the reverse characteristic data is input from the reverse characteristic calculation unit 240, the control unit 250, based on the magnitude of the transmission power of the transmission signal input from the transmission power monitoring unit 260, stores the storage area 222 to the storage unit 220. 224 is selected, and the reverse characteristic data is transferred to the selected storage areas 221 to 224. Accordingly, the corresponding inverse characteristic data corresponding to the magnitude of the transmission power stored in the storage unit 220 including the storage areas 221 to 224 is updated.

Control unit 270 receives a signal indicating the magnitude of the transmission signal from transmission power monitoring unit 260. When transmitting a transmission signal, the control unit 270 selects one of the storage areas 221 to 224 of the storage unit 220 corresponding to the magnitude of the transmission signal input from the transmission power monitoring unit 260, and selects the selected storage The addresses in the regions 221 to 224 are selected, and the inverse characteristic data of the amplifier 210 stored in the selected addresses is output to the distortion compensator 280.

[0017] Distortion compensation section 280 multiplies the transmission signal by a distortion compensation coefficient determined by the inverse characteristic data of the amplification characteristic of amplifier 210 input from control section 270, and outputs the multiplication result to transmission section 290. The transmission unit 290 performs transmission processing for performing digital “analog (DZA) conversion and frequency conversion on the input signal, and outputs a distortion-compensated signal as a processing result to the amplifier 210.

[0018] In this way, the distortion compensation circuit 200 transmits the inverse characteristic data of the amplifier 210 according to the magnitude of the transmission power of the transmission signal to any one of the storage areas 221 to 224, and controls the control unit 250. To store in advance. When the transmission power of the transmission signal changes, the inverse characteristic data determined by the magnitude of the transmission power is read from one of the storage areas 221 to 224 under the control of the control unit 270, and is sent to the distortion compensation unit 280. The signal is output and the compensation characteristic of the distortion compensator 280 is controlled to output a distortion-compensated signal to the amplifier 210 via the transmitter 290. As a result, the amplifier 210 outputs a signal whose distortion is compensated for linearity to the outside.

As described above, the conventional distortion compensation circuit 200 stores the inverse characteristic data according to the magnitude of the transmission power in advance, and reads the inverse characteristic data according to the magnitude of the transmission power of the transmission signal at the time of transmission. Since distortion compensation is performed based on the distortion compensation coefficient determined by the read and read inverse characteristic data, distortion compensation control can be performed over a wide range of transmission power.

Patent Document 1: JP 2001-268150 A

Patent Document 2: JP 2004-336750 A

Disclosure of the invention

Problems to be solved by the invention

However, since the conventional distortion compensation circuit needs to provide a plurality of storage areas for storing the reverse characteristic data, a large amount of memory is required to form the storage area. There is a problem that the scale becomes large. In addition, when the transmission power fluctuation is large or the fluctuation speed is large! / ヽ, or when the transmission power fluctuation is large, such as when the fluctuation width is large! ヽ, the reverse characteristics follow the transmission power fluctuation. It is necessary to switch between them at high speed. A circuit capable of high-speed operation is expensive and complicated. For this reason, the conventional distortion compensation circuit has a problem that the hardware scale increases and the price increases.

[0021] The present invention has been made in view of the problem to be solved. It suppresses an increase in the hardware scale of a distortion compensation circuit and ensures distortion compensation performance even when transmission power fluctuates, thereby ensuring linearity. An object of the present invention is to provide a distortion compensation circuit capable of outputting a high transmission signal and a control method thereof. Means for solving the problem

[0022] In order to solve the problem, the distortion compensation circuit of the present invention compares an amplification unit for amplifying a transmission signal with a transmission signal before and after the amplification, thereby obtaining an inverse characteristic of the amplification characteristic of the amplification means. A reverse characteristic calculating means for calculating; a reverse characteristic storage control means for storing the calculated reverse characteristic based on a transmission power of the transmission signal; and And a distortion compensation unit that compensates distortion of the transmission signal before being amplified by the amplification unit.

[0023] In addition, the distortion compensation circuit of the present invention compares the transmission signal before and after the amplification based on the transmission power of the transmission signal and amplification means for amplifying the transmission signal, thereby amplifying the amplification means. Inverse characteristic calculation control means for calculating the reverse characteristic of the characteristic, reverse characteristic storage means for storing the calculated reverse characteristic, and distortion compensation for the transmission signal having the stored reverse characteristic before being amplified by the amplifying means. And a distortion compensation means.

[0024] In addition, the distortion compensation circuit control method of the present invention compares the amplification step of amplifying a transmission signal with an amplifier and the transmission signal before and after the amplification, thereby obtaining an inverse characteristic of the amplification characteristic of the amplifier. A reverse characteristic calculation step to calculate; a reverse characteristic storage control step to store the calculated reverse characteristic based on the transmission power of the transmission signal; and a transmission before amplification in the amplification step with the stored reverse characteristic A distortion compensation step for compensating for distortion of the signal.

[0025] In addition, the distortion compensation circuit control method of the present invention compares an amplification step of amplifying a transmission signal with an amplifier and a transmission signal before and after amplification based on the transmission power of the transmission signal. The reverse characteristic calculation control step for calculating the reverse characteristic of the amplification characteristic of the amplifier, the reverse characteristic storage step for storing the calculated reverse characteristic, and the transmission before amplification in the amplification step with the stored reverse characteristic A distortion compensation step for compensating for distortion of the signal.

The invention's effect

[0026] According to the present invention, it is possible to provide a distortion compensation circuit capable of ensuring distortion compensation performance even when transmission power fluctuates and a control method thereof, while suppressing an increase in hardware scale of the distortion compensation circuit.

Brief Description of Drawings

[0027] FIG. 1 is a diagram for explaining the operation principle of a predistortion method in a wireless communication device.

FIG. 2 is a block diagram showing the configuration of a conventional distortion compensation circuit

FIG. 3 is a block diagram showing a configuration of a distortion compensation circuit according to the first embodiment of the present invention.

FIG. 4 is a flowchart showing the operation of the distortion compensation circuit according to the first embodiment of the present invention. [Figure 5] Diagram showing input / output characteristics of distortion compensation section

[Fig. 6] Diagram showing comparison of spectrum between input signal of distortion compensator and output signal after distortion compensation [Fig. 7] Diagram showing input / output characteristics of distortion compensator

[Fig. 8] Diagram showing comparison of spectrum between input signal of distortion compensation unit and output signal after distortion compensation [Fig. 9] Diagram showing comparison of spectrum of input signal of distortion compensation unit and output signal after distortion compensation [Fig. 10] Block diagram showing the configuration of the distortion compensation circuit according to the second embodiment of the present invention.

FIG. 11 is a flowchart showing the operation of the distortion compensation circuit according to the second embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

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

[0029] (Embodiment 1)

FIG. 3 is a block diagram showing a configuration of distortion compensation circuit 300 according to Embodiment 1 of the present invention.

[0030] Amplifier 310 amplifies a signal input from transmission section 380 described later, outputs the amplified signal to the outside, and outputs a part of the output signal to reception section 320. The amplification characteristic of the amplifier 310 is nonlinear.

[0031] Receiving section 320 converts the output signal of amplifier 310 into a signal form suitable for input to inverse characteristic calculation section 330. Specifically, it converts the radio frequency signal output from the amplifier 310, performs quadrature demodulation, converts the analog signal into a digital signal (AZD conversion), etc., and converts it into a digital signal that can be handled by the inverse characteristic calculator 330. Convert.

[0032] Inverse characteristic calculation section 330 compares the transmission signal and the signal from reception section 320, detects distortion generated during amplification by amplifier 310, and indicates the inverse characteristic of the amplification characteristic of amplifier 310. Calculate the reverse characteristic data. The reverse characteristic calculation unit 330 outputs the calculated reverse characteristic data to the control unit 340.

[0033] Transmission power monitoring section 350 receives a transmission signal, calculates the transmission power of the transmission signal, and outputs the calculated transmission power value to control section 340.

[0034] The control unit 340 receives the transmission power value from the transmission power monitoring unit 350, and when the received transmission power value is equal to or more than a predetermined threshold, the inverse characteristic received from the inverse characteristic calculation unit 330 Write data to the storage unit 360, and the received transmission power value is smaller than the threshold value V, if not, do not write reverse polarity data to storage 360.

Storage unit 360 stores data indicating the reverse characteristic of amplifier 310 (hereinafter, “data indicating the reverse characteristic of amplifier 310” is referred to as reverse characteristic data). The storage unit 360 outputs the reverse characteristic data input and stored from the control unit 340 to the distortion compensation unit 370.

The distortion compensation unit 370 multiplies the transmission signal, which is one input, by a distortion compensation coefficient determined by the inverse characteristic data input from the storage unit 360, and outputs a distortion-compensated signal to the transmission unit 380. To do.

Transmitting section 380 converts the input distortion-compensated signal into a signal form appropriate for driving amplifier 310 and outputs the signal to amplifier 310. Specifically, the input digital signal is converted to an analog signal (DZA conversion), quadrature modulated, and frequency-converted according to the radio frequency, etc., and converted to a signal level suitable for driving the amplifier 310. Is output to the amplifier 310.

FIG. 4 is a flowchart for explaining the operation of the distortion compensation circuit 300 according to the first embodiment.

Hereinafter, the operation of the distortion compensation circuit 300 will be described. First, based on the transmission signal and the digital signal output from receiving section 320 indicating the output signal of amplifier 310, inverse characteristic data is calculated by inverse characteristic calculating section 330 and output to control section 340 (ST301).

Next, control section 340 determines whether or not the transmission power value output from transmission power monitoring section 350 is greater than or equal to a predetermined threshold value (ST302). If it is equal to or greater than the threshold value (ST302: YES), control unit 340 rewrites the stored contents of storage unit 360 with the inverse characteristic data (ST 303). When it is less than the threshold value (ST302: NO), control unit 340 does not rewrite the reverse characteristic data of storage unit 360. As a result, the control unit 340 performs update control of the reverse characteristic data that rewrites the contents of the storage unit 360 only when the transmission power value is greater than or equal to the threshold value.

[0041] When the inverse characteristic data update control (ST303) is thus completed, the distortion compensation circuit 300 returns the control to step ST301 and repeats the same control.

Hereinafter, the effectiveness of the present invention will be described using simulation calculation results.

FIG. 5 is a diagram showing the input / output characteristics of the distortion compensator 370. In FIG. 5, the inverse characteristics of the amplifier 310 obtained by simulation calculation when the amplifier 310 operates at maximum power (actual Line) and the inverse characteristic (dashed line) of the amplifier 310 calculated theoretically. In FIG. 5, the amplifier 310 has a linearization gain of 1 and a maximum output amplitude of 0.85. As can be seen from FIG. 5, the inverse characteristics of the amplifier 310 obtained by the simulation calculation agree well with the inverse characteristics of the amplifier 310 obtained theoretically. Figure 6 shows the output signal spectrum when the distortion compensation unit 370 performs distortion compensation using this inverse characteristic.

FIG. 6 is a diagram showing a comparison of the spectrum of the input signal of the distortion compensator 370 and the output signal after distortion compensation. From Fig. 6, it is clear that the distortion caused by passing through the amplifier is suppressed to several dB.

[0045] Fig. 7 shows the inverse characteristic (solid line) obtained by simulation calculation when amplifier 310 is operating with the transmission power 1.5 dB lower than the maximum transmission power, and the theoretically calculated amplification. It is the figure which showed the reverse characteristic (dashed line) of the vessel. The maximum output amplitude at this time is 0.72.

As shown in FIG. 7, in the low amplitude region, the reverse amplitude characteristic of the amplifier 310 obtained by the simulation calculation and the reverse characteristic of the amplifier 310 obtained theoretically are the same. In the high region, the simulation calculated value and the theoretical value are greatly different. Figures 8 and 9 show the output signal spectrum when distortion compensation is performed using this inverse characteristic.

FIG. 8 shows a distortion compensation result when the transmission power is 1.5 dB lower than the maximum transmission power (that is, the same power as when calculating the reverse characteristics). As can be seen from FIG. 8, the distortion caused by passing through the amplifier 310 is suppressed to several dB.

FIG. 9 shows a distortion compensation result when the amplifier operates at the maximum power. It can be seen that the output signal spectrum of the amplifier 310 is greatly degraded compared to the case of FIG. 8 where the transmission power is 1.5 dB lower than the maximum transmission power.

The reason why the output signal spectrum shown in FIG. 9 deteriorates will be described below.

There are various methods for calculating the inverse characteristics of the amplifier 310. However, in any method, it is not possible to accurately estimate the inverse characteristic at an amplitude larger than the maximum amplitude of the data used for the calculation. Specifically, if the maximum amplitude is 0.72, the reverse characteristic up to 0.72 can be correctly estimated. If the amplitude is larger than 0.72 (for example, 0.85), the correct reverse characteristic may not be obtained. . Therefore, the amplitude distribution of the transmission signal that is the input signal of the distortion compensator 370 should be less than the maximum amplitude (i.e., 0.72) used in the 1S simulation calculation. Figure 9 shows that distortion compensation performance deteriorates if the amplitude distribution exceeds the maximum amplitude used in the simulation calculation.

[0051] On the other hand, the inverse characteristic estimated using a signal with a maximum amplitude of 0.72 has sufficient distortion compensation performance for a signal with a maximum amplitude smaller than 0.72, for example, a maximum amplitude of 0.65. Can be secured. The present invention takes advantage of this fact and updates the reverse characteristic data only when the transmission power is high, and does not update the reverse characteristic data when the transmission power is low.

As described above, according to the distortion compensation circuit of the first embodiment, when the transmission power value detected by transmission power monitoring section 350 is larger than a predetermined threshold, the stored contents of storage section 360 are reversed. Update characteristic data. As a result, according to the distortion compensation circuit 300 of the first embodiment, the reverse characteristics obtained when the transmission power is high can be applied even when the transmission power is low. High distortion compensation performance can be obtained. Also, according to the distortion compensation circuit 300 of the first embodiment, when the transmission power value detected by the transmission power monitoring unit 350 is smaller than the threshold value, the inverse characteristic data is not updated and the previous inverse characteristic data is maintained. Thus, according to the distortion compensation circuit 300 of the first embodiment, the distortion compensation is performed based on the inverse characteristic obtained when the transmission power is low, and the problem that the distortion compensation performance is greatly deteriorated can be avoided. it can. In addition, according to the distortion compensation circuit 300 of the first embodiment, the distortion compensation unit 370 uses a plurality of inverse characteristics that are determined for each transmission power according to the magnitude of the transmission power value as conventionally employed. However, distortion compensation is performed based on a single inverse characteristic regardless of the transmission power, so that the hardware for realizing the distortion compensation circuit can be reduced in size and compensated at high speed.

[0053] (Embodiment 2)

FIG. 10 is a block diagram showing a configuration of distortion compensation circuit 1000 according to Embodiment 2 of the present invention. In the figure, the same blocks as those in FIG. 3 are denoted by the same reference numerals and description thereof is omitted. FIG. 11 is a flowchart for explaining the operation of the distortion compensation circuit 1000 according to the second embodiment. In FIG. 11, steps equivalent to those in FIG. 4 are given the same reference numerals. In FIG. 10, the storage unit 1001 stores the reverse characteristic data input from the reverse characteristic calculation unit 1002 and outputs it to the distortion compensation unit 370. The inverse characteristic calculation unit 1002 is activated by the output of the transmission power monitoring unit 1003 and is calculated by the transmission power monitoring unit 1003. Is equal to or greater than the threshold value, the transmission signal is compared with the signal from the receiving unit 320, and when the amplification by the amplifier 310 is performed, the inverse characteristic data indicating the inverse characteristic of the distortion generated in the transmission signal is obtained. Is calculated and output to the storage unit 1001.

[0054] In the distortion compensation circuit 1000 according to the second embodiment, the distortion compensation circuit 300 according to the first embodiment always calculates the inverse characteristic data by the inverse characteristic calculation unit 330, as shown in FIG. 10 and FIG. However, there is a difference in that the calculation of inverse characteristics is performed only when the transmission power of the transmission signal is equal to or greater than the threshold value.

Hereinafter, the operation of the distortion compensation circuit 1000 will be described with reference to FIGS. 10 and 11.

[0056] When distortion operation circuit 1000 starts operating, transmission power monitoring section 1003 calculates the transmission power of the transmission signal, and determines that the calculated transmission power value is equal to or greater than a threshold (ST1001). If the determination result is NO (ST1001: NO), distortion compensation circuit 1000 returns control to step ST1001 without doing anything.

[0057] If the transmission power value is greater than or equal to the threshold (ST1001: YES), distortion compensation circuit 1000 moves control to step ST301, and transmission power monitoring section 1003 activates inverse characteristic calculation section 1002. The activated inverse characteristic calculation unit 1002 calculates inverse characteristic data based on the transmission signal and the digital signal output from the reception unit 320 indicating the output signal of the amplifier 310 (ST301).

In next step ST303, inverse characteristic calculation section 1002 rewrites the inverse characteristic data corresponding to the transmission power value, which is the content of storage section 1001 (ST303). When the reverse characteristic data update control (ST303) is thus completed, the distortion compensation circuit 1000 returns the control to step ST1001.

As described above, according to the distortion compensation circuit 1000 according to the second embodiment, in contrast to the effect of the first embodiment, only when the transmission power value is equal to or greater than a predetermined value and reverse characteristic data update control is performed, Since the characteristic calculation unit 1002 is activated, the circuit operation opportunities for calculating the reverse characteristic data are reduced, and the power consumption of the entire circuit can be reduced. By reducing this power consumption, it is possible to improve the performance of the wireless communication device by increasing the standby time or downsizing the device.

In Embodiments 1 and 2, inverse characteristic data is calculated using an input signal (that is, a transmission signal) of distortion compensation section 370 and an output signal of amplifier 310 via reception section 320. However, this may be calculated based on the output signal of the distortion compensator 370 and the output signal of the amplifier 310. According to the latter method, the amount of calculation for obtaining the reverse characteristic increases, but the accuracy of the reverse characteristic is improved, and the stability of the circuit during the calculation operation is improved.

In the distortion compensation circuits according to Embodiments 1 and 2, the transmission power value is detected using the transmission signal that is the input signal, but the method of detecting the transmission power is not limited to this. The transmission power value can also be obtained by the following method.

[0062] For example, in the case of a single carrier W—CDMA signal, the W—CDMA signal is multiplexed, and the transmission power value changes from the number of users and the power value of each user. Can be obtained. In the case of a multi-carrier W—CDMA signal, the power of each W—CDMA signal is calculated in the same manner as in the case of a single carrier W—CDMA signal, and the transmission power value can be obtained by adding them.

[0063] In the case of an OFDM signal, since the power of the OFDM signal is proportional to the number of subcarriers, the number of subcarriers can be used as the transmission power value.

[0064] In the case of time division duplex (TDD), control information and data are transmitted in a time-sharing manner, so the transmission power value when transmitting data varies depending on the number of users. Therefore, the transmission power value fluctuates, but the control information transmits a power value close to the maximum regardless of the number of users. In the case of TDD, using this property, control information is transmitted, the transmission power value is obtained at the timing when it is transmitted, and update control may be performed.

Industrial applicability

The present invention can be applied to a predistortion distortion compensation circuit.

Claims

The scope of the claims

[1] an amplification means for amplifying the transmission signal;

An inverse characteristic calculating means for calculating an inverse characteristic of the amplification characteristic of the amplifying means by comparing transmission signals before and after the amplification;

Reverse characteristic storage control means for storing the calculated reverse characteristic based on the transmission power of the transmission signal;

Distortion compensation means for compensating for distortion with respect to the transmission signal before amplification by the amplification means with the stored reverse characteristics;

A distortion compensation circuit comprising:

2. The distortion compensation circuit according to claim 1, wherein the inverse characteristic storage control means stores the inverse characteristic calculated when the transmission power of the transmission signal is equal to or greater than a threshold value.

[3] amplification means for amplifying the transmission signal;

Based on the transmission power of the transmission signal, by comparing the transmission signal before and after the amplification, inverse characteristic calculation control means for calculating the reverse characteristic of the amplification characteristic of the amplification means, and storing the calculated reverse characteristic Reverse characteristic storage means,

A distortion compensation circuit comprising:

4. The distortion compensation circuit according to claim 3, wherein the inverse characteristic calculation control means calculates the inverse characteristic when the transmission power of the transmission signal is equal to or greater than a threshold value.

5. The distortion compensation circuit according to claim 1, wherein the distortion compensation means performs the distortion compensation by multiplying a magnitude of the transmission signal and a distortion compensation coefficient determined corresponding to the inverse characteristic.

[6] an amplification step of amplifying the transmission signal with an amplifier;

An inverse characteristic calculating step of calculating an inverse characteristic of the amplification characteristic of the amplifier by comparing the transmission signals before and after the amplification;

Based on the transmission power of the transmission signal !, a reverse characteristic storage control step for storing the calculated reverse characteristic;

With the stored reverse characteristics, distortion correction is performed on the transmission signal before amplification in the amplification step. A distortion compensation step to compensate;

A method for controlling a distortion compensation circuit comprising:

An amplification step of amplifying the transmission signal with an amplifier;

Based on the transmission power of the transmission signal, the inverse characteristic calculation control step of calculating the inverse characteristic of the amplification characteristic of the amplifier by comparing the transmission signal before and after the amplification, and storing the calculated inverse characteristic An inverse characteristic storing step;

A distortion compensation step of compensating for distortion with respect to the transmission signal before amplification in the amplification step with the stored reverse characteristics;

A method for controlling a distortion compensation circuit comprising: