JP2012095071A - Radio communication apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication apparatus that ensures a reduced power consumption.SOLUTION: A radio communication apparatus includes: a D/A converter 12 for converting a transmission signal from a digital format to an analog format; an amplifier 14 for amplifying the transmission signal output from the D/A converter 12 and outputting it; an A/D converter 19 for converting the amplified transmission signal output from the amplifier 14 from an analog format to a digital format; a distortion compensation section 5 for distortion-compensating the amplified transmission signal; and a distorted band detection section 7 for detecting a band to be distortion-compensated in the amplified transmission signal. The sampling frequency of the D/A converter 12 and the A/D converter 19 is controlled in accordance with the band to be distortion-compensated which was detected by the distorted band detection section 7.

Description

  The present invention relates to a wireless communication apparatus, and more particularly to a wireless communication apparatus that performs distortion compensation processing on a transmission signal.

  In a wireless communication device, for example, as disclosed in Patent Document 1, in order to compensate for distortion of a transmission signal amplified by a power amplification unit, distortion in digital processing called DPD (Digital Pre-Distortion) Compensation processing has been proposed.

  In Patent Document 1, in the input / output characteristics of an amplifier, the sampling interval of the distortion correction amount to be compensated is wide in the region where the distortion is small and exhibits linearity, and the distortion correction amount to be compensated in the region where the distortion is large and exhibits non-linearity. The sampling interval is narrowed to reduce the amount of distortion compensation data to be stored.

JP 2002-135349 A

  In order to compensate for distortion, not only a communication band but also a signal in a band to be compensated for (distortion band) is necessary. This distortion band becomes wider as the transmission output (transmission power) increases, and becomes considerably wider than the communication band depending on the transmission power. And the wider the band to be processed, the more D / A converters and A / D converters that operate at higher speeds are required, and the amount of calculation in the arithmetic unit increases and the power consumption also increases. there were.

  In the above-mentioned Patent Document 1, a technique for reducing the memory capacity by reducing the amount of distortion compensation data to be stored for distortion compensation is disclosed, but the above-described problem has not been solved. Absent.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a wireless communication apparatus with reduced power consumption.

  In order to solve the above problems, a wireless communication apparatus according to the present invention amplifies a D / A converter that converts a transmission signal from a digital format to an analog format, and a transmission signal that is output from the D / A converter. An amplifier that outputs, an A / D converter that converts an amplified transmission signal output from the amplifier from an analog format to a digital format, a distortion compensation unit that receives the amplified transmission signal and performs distortion compensation; A distortion band detection unit for detecting a band to be compensated for distortion in the amplified transmission signal, and based on the band to be compensated for distortion detected by the distortion band detection unit, the D / A converter and the Control the sampling frequency of the A / D converter.

  The wireless communication apparatus according to the present invention can reduce power consumption.

It is a figure which shows notionally the spectrum waveform of a transmission signal. It is a figure which shows notionally the spectrum waveform of a transmission signal. It is a figure which shows notionally the spectrum waveform of a transmission signal. It is a block diagram which shows the structure of the radio | wireless communication apparatus of embodiment which concerns on this invention. It is a flowchart explaining the change operation of the sampling frequency of a D / A converter and an A / D converter. A table of bands necessary for distortion compensation for transmission power will be described. It is a figure which shows the input-output characteristic of an amplifier. It is a block diagram which shows the structure of the modification 1 of the radio | wireless communication apparatus of embodiment which concerns on this invention. It is a flowchart explaining the change operation of the sampling frequency of a D / A converter and an A / D converter. It is a block diagram which shows the structure of the modification 2 of the radio | wireless communication apparatus of embodiment which concerns on this invention. It is a flowchart explaining the change operation of the sampling frequency of a D / A converter and an A / D converter.

<Embodiment>
First, the relationship between the communication band and the band to be compensated for distortion will be described with reference to FIGS. 1 to 3 conceptually showing the spectrum waveform of the transmission signal.

  FIG. 1 shows a spectrum waveform of a transmission signal when the communication band is relatively wide, with the horizontal axis indicating frequency and the vertical axis indicating transmission power.

  In FIG. 1, the spectrum waveform has a mountain shape that protrudes at the center and has a flat top, and the mountain skirt portion is inclined. In such a spectrum waveform, the width A of the protruding portion at the center corresponds to the communication band, and the entire width B of the spectrum waveform including the peak portion corresponds to the band necessary for distortion compensation. A band corresponding to the width C and the width D corresponding to the mountain skirt portion is a band (distortion band) to be subjected to distortion compensation.

  The distortion band corresponding to the width C and the width D increases as the communication band increases, and increases as the transmission power increases.

  FIG. 2 shows a spectrum waveform of a transmission signal when the communication band is relatively narrow. When the communication band is narrow, the distortion band is also narrowed.

  FIG. 3 shows a spectrum waveform SP1 (displayed with a solid line) having a relatively large transmission power and a spectrum waveform SP2 (displayed with a broken line) having a transmission power smaller than that of the spectrum waveform SP1. In both spectrum waveforms, the communication band is the same.

  From FIG. 3, it can be seen that if the communication band is the same, the distortion band increases or decreases depending on the transmission power, and if the communication band is fixed, the distortion band is determined according to the transmission power.

<Device configuration>
FIG. 4 is a block diagram showing a configuration of radio communication apparatus 100 according to the embodiment. As illustrated in FIG. 4, the wireless communication device 100 includes a control unit 1, a wireless communication unit RX, and a digital processing unit DP, and D / A conversion is performed between the wireless communication unit RX and the digital processing unit DP. The digital data and the analog data are exchanged by the device 12 and the A / D converters 19 and 21.

  The radio communication unit RX converts the received signal in the carrier band received by the antenna AT into a received signal in the base band, and outputs the received signal in the base band. The radio communication unit RX converts the baseband transmission signal output from the D / A converter 12 into a transmission signal in the carrier band, and wirelessly transmits the transmission signal in the carrier band from the antenna AT.

  The D / A converter 12 converts the transmission signal output from the digital processing unit DP from a digital format to an analog format and outputs the converted signal. The A / D converters 19 and 21 convert the reception signal output from the radio communication unit RX from an analog format to a digital format and output the converted signal.

  The digital processing unit DP generates a digital transmission signal including transmission data for transmission, and inputs the transmission signal to the D / A converter 12. Further, the digital processing unit DP acquires reception data included in the reception signal output from the A / D converter 19.

  The configuration of the radio communication apparatus 100 will be described in more detail. The radio communication unit RX includes an antenna AT, a mixer 13 that receives the output of the D / A converter 12, an amplifier 14 that receives the output of the mixer 13, and an output of the amplifier 14 A selection switch 16 that receives one output of the branch coupler 15 and the branch coupler 15 is provided. Furthermore, the radio communication unit RX includes a mixer 20 that receives the output of the selection switch 16 and a mixer 18 that receives the other output of the branch coupler 15. In addition, the radio communication unit RX includes a local oscillator 17 that supplies an output signal for multiplying the mixers 13, 18, and 21.

  The mixer 13 multiplies the transmission signal output from the D / A converter 12 and the output signal of the local oscillator 17. The amplifier 14 amplifies the transmission signal output from the mixer 13 and outputs it.

  The transmission signal in the carrier band output from the mixer 13 is amplified by the amplifier 14, the transmission signal amplified by the amplifier 14 is branched into two by the branch coupler 15, and one transmission signal is given to the selection switch 16. The other transmission signal is supplied to the mixer 18.

  The selection switch 16 is a switch that selects whether the transmission signal output from the branch coupler 15 is transmitted from the antenna AT or the reception signal received by the antenna AT is input to the mixer 20, and is output from the branch coupler 15. The transmitted signal is input from terminal A, and the received signal received by antenna AT is output through terminal B. Therefore, the selection switch 16 is switched to select the terminal A when transmitting the transmission signal output from the branch coupler 15 from the antenna AT, and when outputting the reception signal received by the antenna AT, It is switched to select terminal B. The switching operation of the selection switch 16 is controlled by the control unit 1.

  The A / D converter 19 converts the output signal of the mixer 18 from an analog format to a digital format. That is, when a transmission signal is supplied from the branch coupler 15 to the mixer 18, the output signal of the amplifier 14 fed back from the transmission system circuit is down-converted and input to the A / D converter 19.

  The A / D converter 21 converts the output signal of the mixer 21 from an analog format to a digital format. That is, when the selection switch 16 outputs a reception signal received by the antenna AT, the reception signal is down-converted and input to the A / D converter 21.

  The digital processing unit DP is configured by a CPU, a memory, and the like. As a functional block, the transmission signal generation unit 2, the communication band determination unit 3, the transmission signal adjustment unit 4, the DPD unit 5, the clock change unit 6, the communication band / A transmission power monitoring unit 7, a clock oscillator 8, a modulation unit 11, demodulation units 22 and 23, and a reception processing unit 24 are provided.

  The control unit 1 controls each unit in the wireless communication apparatus 100, and the transmission signal generation unit 2 generates and outputs a digital transmission signal SS including transmission data for transmission.

  The transmission signal SS is given to the DPD unit 5 via the communication band determination unit 3 and the signal band conversion unit 4.

  The DPD unit 5 (distortion compensation unit) stores a distortion compensation value table in which distortion compensation values for compensating for distortion of the transmission signal amplified by the amplifier 14 are registered, and based on the distortion compensation value table. The transmission signal SS is compensated by adjusting the amplitude and phase of the transmission signal SS.

  The transmission signal amplified by the amplifier 14 is fed back to the DPD unit 5 through the A / D converter 19 and the demodulation unit 22, and the DPD unit 5 transmits the amplified transmission signal and the transmission signal SS before amplification. Based on the above, the distortion of the amplified transmission signal is estimated, and the distortion compensation value table is created based on the estimation result.

  The transmission signal compensated by the DPD unit 5 is supplied to the modulation unit 11 and modulated, and then supplied to the D / A converter 12.

  In the present invention, the configuration of the DPD unit 5 is not limited, and the configuration described above is merely an example, and any configuration may be adopted as long as DPD can be realized.

  Further, the output of the A / D converter 21 is given to the demodulator 23, demodulated by the demodulator 23, and given to the reception processor 24. That is, when the selection switch 16 outputs a reception signal received by the antenna AT, the reception signal down-converted via the A / D converter 21 is given to the demodulation unit 23 and received by the reception processing unit 24. Receive data included in the signal is acquired.

  The communication band determining unit 3 is configured to determine the communication band of the transmission signal SS and to give the information to the communication band / transmission power monitoring unit 7.

  The communication band / transmission power monitoring unit 7 receives the transmission power of the amplified transmission signal, which is one output of the branch coupler 15, and the communication band information determined by the communication band determination unit 3, and stores them in the storage unit 71. A band necessary for distortion compensation is derived based on the table of bands necessary for distortion compensation obtained by changing the transmission power for each communication band. Then, the distortion band is determined based on the band necessary for the obtained distortion compensation, and the D / A converter 12 and the A / D converter 19 are clocked so that the sampling frequency is suitable for the obtained distortion band. The clock changing unit 6 is controlled so that the frequency of the clock signal supplied from the oscillator 8 is changed using the clock changing unit 6. Note that the communication band / transmission power monitoring unit 7 ultimately determines a distortion band and can be referred to as a distortion band determination unit. In FIG. 4, the storage unit 71 is shown as a configuration separate from the communication band / transmission power monitoring unit 7, but may be included in the communication band / transmission power monitoring unit 7.

  Here, the clock changing unit 6 may be realized by a shift register including a flip-flop circuit that receives a clock signal supplied from the clock oscillator 8 and outputs a signal of a predetermined frequency, for example. A plurality of shift registers having different output signal frequencies are prepared, and a plurality of shift registers are switched based on an instruction from the communication band / transmission power monitoring unit 7 to obtain an output signal having a desired frequency. The output signal may be used as a clock signal whose frequency is changed. It should be noted that the realization of the clock changing unit 6 with a shift register composed of a flip-flop circuit is merely an example, and it goes without saying that other configurations may be used.

  The clock signal whose frequency is changed by the clock changing unit 6 is given to the transmission signal adjusting unit 4, the DPD unit 5, the D / A converter 12 and the A / D converter 19. When no instruction to change the clock frequency is issued from the communication band / transmission power monitoring unit 7, the clock signal output from the clock oscillator 8 is transmitted to the transmission signal adjustment unit 4, the DPD unit 5, the D / A converter 12, and The A / D converter 19 is configured to be supplied.

  Since the transmission signal SS is created based on a clock signal having a predetermined frequency (supplied from the clock oscillator 8) in the transmission signal generation unit 2, the frequency of the clock signal is changed by the clock change unit 6. In this case, the transmission signal SS is adjusted in the transmission signal adjustment unit 4 according to the frequency.

<Operation>
Next, the sampling frequency changing operation in the D / A converter 12 and the A / D converter 19 in the wireless communication apparatus 100 will be described using the flowchart shown in FIG.

  When the transmission operation is started, the communication band determining unit 3 determines the communication band for the transmission signal SS output from the transmission signal generating unit 2, and the information is given to the communication band / transmission power monitoring unit 7. The band / transmission power monitoring unit 7 detects the communication band (step S1).

  Thereafter, the transmission signal SS is given to the radio communication unit RX via the transmission signal adjustment unit 4, the DPD unit 5, the modulation unit 11, and the D / A converter 12, amplified by the amplifier 14, and output from the branch coupler 15. The The amplified transmission signal is given to the communication band / transmission power monitoring unit 7, and the transmission power is detected (step S2).

  The communication band / transmission power monitoring unit 7 determines a band necessary for distortion compensation based on a table of bands necessary for distortion compensation obtained by changing the transmission power for each communication band stored in the storage unit 71. To derive.

  Here, a table of a band necessary for distortion compensation for transmission power will be described with reference to FIG. FIG. 6 is a table showing a band necessary for distortion compensation when the transmission power is changed in the range of −6 dBm to −25 dBm when the communication band is 10 MHz and 20 MHz, and is a table obtained by actual measurement. It is.

  FIG. 6 shows that the higher the transmission power, the wider the band necessary for distortion compensation, and the wider the signal band, the wider the band necessary for distortion compensation. Therefore, if the communication band is fixed, the band necessary for distortion compensation is determined according to the transmission power. By using such a table, if the communication band and transmission power are known, the band necessary for distortion compensation is derived. Can be easily done.

  In the above, the case where the communication band is 10 MHz and the case of 20 MHz are shown, but this is an example, and if a PHS (Personal Handyphone System) is used, communication bands such as 5 MHz and 15 MHz are also used. A similar table is created for them, and when another communication method is adopted, a similar table may be created for a communication band adapted to the communication method.

  Further, the table prepared in advance may be used in a fixed manner, but an updated table may be used as appropriate.

  The communication band / transmission power monitoring unit 7 derives a band necessary for distortion compensation, and then determines a band (distortion band) for distortion compensation based on the derived band (step S3). This determination is most simply performed by subtracting the communication band value from the band value necessary for distortion compensation. That is, for example, if the communication band is 10 MHz and the transmission power is −6 dBm, it can be seen from the table in FIG. 6 that the band value necessary for distortion compensation is 54.4 MHz. If the communication band value of 10 MHz is subtracted from this, the distortion band becomes 44.4 MHz. When the distortion band is determined, the process proceeds to step S4, and the operations of steps S1 to S3 are repeated until the distortion band is determined.

  Next, the communication band / transmission power monitoring unit 7 determines the sampling frequencies of the D / A converter 12 and the A / D converter 19 based on the obtained distortion band (step S4). Specifically, a desired sampling frequency is obtained by changing the frequency of the clock signal supplied from the clock oscillator 8 using the clock changing unit 6.

  Here, the sampling frequency is determined based on the input / output characteristics of the amplifier 14. FIG. 7 shows input / output characteristics of the amplifier 14. In FIG. 7, the horizontal axis indicates the input signal level, the vertical axis indicates the output signal level, the solid line characteristic C1 indicates the actual input / output characteristic, and the broken line characteristic C2 indicates the ideal input / output characteristic. From FIG. 7, it can be seen that when the input is relatively small, the characteristics C1 and C2 show linearity, and they both agree well, but when the input increases, the deviation from the characteristic C2 increases. Since the deviation from the characteristic C2 causes distortion, the DPD unit 5 performs distortion compensation by giving a compensation signal line-symmetric to the characteristic C2 so as to cancel out the characteristic C1, and is close to the characteristic C1. I try to get the characteristics.

  In the present embodiment, the sampling frequency is determined depending on which part of the input / output characteristics as shown in FIG. 7 corresponds to the distortion band calculated in step S3. For example, if the calculated distortion band has a relatively small deviation from the characteristic C2 and corresponds to the vicinity of a portion having linearity, the sampling frequency is relatively lowered to reduce sampling data. On the other hand, when the calculated distortion band has a relatively large deviation from the characteristic C2, the sampling frequency is set relatively high to increase the sampling data.

  Here, if the relationship between the distortion band and the input / output characteristics, the relationship between the input / output characteristics and the sampling frequency, and the relationship between the sampling frequency and the frequency of the clock signal are obtained in advance, the sampling frequency is obtained by obtaining the distortion band. It can be determined uniquely.

  After the sampling frequency is determined in step S4, D / A conversion and A / D conversion are performed at the sampling frequency. When transmission data transmission is completed, the transmission operation is terminated and untransmitted transmission data is transmitted. If there is, the operation after step S1 is repeated.

  As described above, a band to be compensated for distortion (distortion band) is calculated based on a table of bands necessary for distortion compensation with respect to transmission power, and the D / A converter 12 and A / D are matched to the distortion band. By determining the sampling frequency of the converter 19, the number of data to be processed by the D / A converter 12 and the A / D converter 19 can be limited, and the D / A converter 12 and the A / D converter 19 does not require high-speed operation. For this reason, it is possible to downgrade the specifications of the D / A converter 12 and the A / D converter 19, and the manufacturing cost of the wireless communication device 100 can be reduced. Further, if the sampling data is reduced, the calculation amount in the arithmetic device is reduced, and the power consumption can be reduced.

<Modification 1>
In the wireless communication apparatus 100 according to the embodiment described above, a configuration for calculating a band (distortion band) for distortion compensation from a table of bands necessary for distortion compensation with respect to transmission power is employed. Of these, a configuration may be adopted in which the distortion band is calculated using an approximate expression representing the characteristics of the nonlinear region. FIG. 8 is a block diagram illustrating a configuration of a wireless communication device 100A that employs the configuration. Note that the same components as those of the wireless communication apparatus 100 illustrated in FIG. 4 are denoted by the same reference numerals, and redundant description is omitted.

  In the radio communication apparatus 100A shown in FIG. 8, the output of the DPD unit 5 is given to the modulation unit 11 and also to the approximate expression calculation unit 9, and the calculation result in the approximate expression calculation unit 9 is given to the FFT unit 10. Thus, it is converted into a transmission signal of a frequency axis component by performing FFT processing, and is provided to the distortion band detection unit 7A.

  The distortion band detection unit 7A detects a band necessary for distortion compensation from the transmission signal of the frequency axis component, and calculates the distortion band using the communication band information provided from the communication band determination unit 3. Then, the frequency of the clock signal supplied from the clock oscillator 8 to the D / A converter 12 and the A / D converter 19 is changed using the clock changing unit 6 so that the sampling frequency is suitable for the obtained distortion band. It is the composition to do.

  The sampling frequency changing operation in the D / A converter 12 and the A / D converter 19 in the wireless communication apparatus 100A described above will be described with reference to the flowchart shown in FIG.

  When the transmission operation is started, the communication band determining unit 3 determines the communication band for the transmission signal SS output from the transmission signal generating unit 2, and the information is given to the distortion band detecting unit 7A. A communication band is detected in 7A (step S11).

  Thereafter, the transmission signal SS is given to the radio communication unit RX via the transmission signal adjustment unit 4, the DPD unit 5, the modulation unit 11, and the D / A converter 12, amplified by the amplifier 14, and output from the branch coupler 15. However, the output of the DPD unit 5 is given to the approximate expression calculation unit 9, and the calculation is executed based on the prepared approximate expression representing the characteristics of the amplifier 14, so that the transmission signal including the distortion in the amplifier 14 (approximation) Value) is obtained (step S12). An approximate expression representing the input / output characteristics in the nonlinear region of the amplifier 14 is shown in the following Expression (1).

In the above equation (1), the output of the amplifier 14 is y (t), the input is x (t), and the nonlinear region of the input / output characteristics is represented by an nth order polynomial. The coefficient a _{i of the} polynomial is a distortion compensation coefficient in DPD.

  A transmission signal of a frequency axis component is obtained by performing FFT processing in the FFT unit 10 on the calculation result in the above formula (1) (step S13).

  The transmission signal of the frequency axis component obtained by the FFT processing has a spectrum waveform as shown in FIGS. 1 to 3, and the distortion band detector 7A detects a band necessary for distortion compensation based on the spectrum waveform. Then, the distortion band is determined using the communication band information provided from the communication band determination unit 3 (step S14).

  This determination is most simply performed by subtracting the communication band value from the detected band value necessary for distortion compensation. That is, for example, when the band value necessary for distortion compensation is 54.4 MHz in the communication band of 10 MHz, the distortion band can be set to 44.4 MHz by subtracting the communication band value of 10 MHz from this. When the distortion band is determined, the process proceeds to step S15, and the operations of steps S11 to S14 are repeated until the distortion band is determined.

  Next, the distortion band detector 7A determines the sampling frequencies of the D / A converter 12 and the A / D converter 19 based on the obtained distortion band (step S15). Specifically, a desired sampling frequency is obtained by changing the frequency of the clock signal supplied from the clock oscillator 8 using the clock changing unit 6. The method for determining the sampling frequency is the same as the method described above.

  After the sampling frequency is determined in step S15, D / A conversion and A / D conversion are performed at the sampling frequency. When transmission of transmission data is completed, the transmission operation is terminated and untransmitted transmission data is transmitted. If there is, the operation after step S11 is repeated.

  As described above, in the wireless communication device 100A, the distortion band is calculated using the approximate expression representing the characteristics of the amplifier 14, and the D / A converter 12 and the A / D converter 19 are matched with the distortion band. By determining the sampling frequency, the number of data to be processed by the D / A converter 12 and the A / D converter 19 can be limited, and the D / A converter 12 and the A / D converter 19 operate at high speed. Is not required. For this reason, it is possible to downgrade the specifications of the D / A converter 12 and the A / D converter 19, and the manufacturing cost of the wireless communication device 100 can be reduced. Further, if the sampling data is reduced, the calculation amount in the arithmetic device is reduced, and the power consumption can be reduced.

<Modification 2>
The radio communication apparatus 100 according to the embodiment employs a configuration in which a band (distortion band) to be distortion compensated is calculated from a table of bands necessary for distortion compensation with respect to transmission power, but the output of the D / A converter 12 is used. Alternatively, the FFT processing may be performed to calculate the distortion band. FIG. 10 is a block diagram illustrating a configuration of a wireless communication device 100B that employs the configuration. Note that the same components as those of the wireless communication apparatus 100 illustrated in FIG. 4 are denoted by the same reference numerals, and redundant description is omitted.

  In the wireless communication device 100B shown in FIG. 10, the output of the D / A converter 12 is given to the mixer 13 and also to the FFT unit 10, and is converted into a frequency axis component transmission signal by performing FFT processing. Thus, the configuration is applied to the distortion band detector 7A.

  The distortion band detection unit 7A detects a band necessary for distortion compensation from the transmission signal of the frequency axis component, and calculates the distortion band using the communication band information provided from the communication band determination unit 3. Then, the frequency of the clock signal supplied from the clock oscillator 8 to the D / A converter 12 and the A / D converter 19 is changed using the clock changing unit 6 so that the sampling frequency is suitable for the obtained distortion band. It is the composition to do.

  The changing operation of the sampling frequency in the D / A converter 12 and the A / D converter 19 in the wireless communication apparatus 100A described above will be described using the flowchart shown in FIG.

  When the transmission operation is started, the communication band determining unit 3 determines the communication band for the transmission signal SS output from the transmission signal generating unit 2, and the information is given to the distortion band detecting unit 7A. The communication band is detected in 7A (step S21).

  Thereafter, the FFT unit 10 performs FFT processing on the output of the D / A converter 12 to obtain a transmission signal having a frequency axis component (step S22).

  The signal obtained by the FFT processing has a spectrum waveform as shown in FIGS. 1 to 3, and the distortion band detector 7A detects a band necessary for distortion compensation based on the spectrum waveform. Then, the distortion band is determined using the communication band information provided from the communication band determination unit 3 (step S23).

  As described above, this determination is most simply performed by subtracting the communication band value from the detected band value necessary for distortion compensation. When the distortion band is determined, the process proceeds to step S25, and the operations of steps S21 to S23 are repeated until the distortion band is determined.

  Next, the distortion band detector 7A determines the sampling frequency of the D / A converter 12 and the A / D converter 19 based on the obtained distortion band (step S25). Specifically, a desired sampling frequency is obtained by changing the frequency of the clock signal supplied from the clock oscillator 8 using the clock changing unit 6. The method for determining the sampling frequency is the same as the method described above.

  After the sampling frequency is determined in step S25, D / A conversion and A / D conversion are performed at the sampling frequency. When transmission of transmission data is completed, the transmission operation is terminated and untransmitted transmission data is transmitted. If there is, the operation after step S21 is repeated.

  As described above, in the wireless communication device 100B, FFT processing is performed on the output of the D / A converter 12 to calculate a distortion band, and the D / A converter 12 and the A / D conversion are matched to the distortion band. By determining the sampling frequency of the converter 19, the number of data to be processed by the D / A converter 12 and the A / D converter 19 can be limited, and the D / A converter 12 and the A / D converter 19 can be limited. Without requiring high-speed operation. For this reason, it is possible to downgrade the specifications of the D / A converter 12 and the A / D converter 19, and the manufacturing cost of the wireless communication device 100 can be reduced. Further, if the sampling data is reduced, the calculation amount in the arithmetic device is reduced, and the power consumption can be reduced.

DESCRIPTION OF SYMBOLS 5 DPD part 7 Communication band and transmission power monitoring part 7A Distortion band detection part 9 Approximation formula calculating part 10 FFT part 12 D / A converter 14 Amplifier 19 A / D converter

Claims (5)

A D / A converter for converting a transmission signal from a digital format to an analog format;
An amplifier that amplifies and outputs a transmission signal output from the D / A converter;
An A / D converter for converting the amplified transmission signal output from the amplifier from an analog format to a digital format;
A distortion compensation unit that receives the amplified transmission signal and performs distortion compensation;
A distortion band detector that detects a band to be compensated for distortion in the amplified transmission signal,
A radio communication apparatus that controls the D / A converter and a sampling frequency of the A / D converter based on the band to be compensated for distortion detected by the distortion band detector. The distortion band detection unit,
Monitoring the transmission band of the transmission signal and the transmission power of the amplified transmission signal, and transmitting the amplified signal based on information on a band necessary for distortion compensation obtained by changing the transmission power for each communication band The wireless communication apparatus according to claim 1, wherein a band necessary for the distortion compensation corresponding to a transmission power of a signal is derived, and the band to be compensated for distortion is determined based on the derived band necessary for the distortion compensation. An approximate expression calculation unit that receives an output of the distortion compensation unit and calculates a transmission signal including distortion in the amplifier by applying an approximate expression representing a characteristic of a nonlinear region among the characteristics of the amplifier to the output;
An FFT unit that performs FFT processing on the transmission signal including distortion in the amplifier calculated by the approximate expression calculation unit and outputs the transmission signal as a frequency axis component transmission signal;
The distortion band detection unit detects a band necessary for distortion compensation from the transmission signal of the frequency axis component output from the FFT unit, and the band to be compensated for based on the detected band necessary for the distortion compensation The wireless communication apparatus according to claim 1, wherein: An FFT unit that receives the output of the D / A converter, performs FFT processing on the output, and outputs the output signal as a frequency axis component transmission signal;
The distortion band detection unit detects a band necessary for distortion compensation from the transmission signal of the frequency axis component output from the FFT unit, and the band to be compensated for based on the detected band necessary for the distortion compensation The wireless communication apparatus according to claim 1, wherein: The D / A converter and the sampling frequency of the A / D converter are set based on a clock signal,
The radio communication apparatus according to claim 1, wherein the sampling frequency is changed by changing a frequency of the clock signal based on the band to be compensated for distortion detected by the distortion band detection unit.

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