JP2008098781A - Communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely compensate for nonlinear distortion of a reception system without increasing a circuit scale. <P>SOLUTION: A communication apparatus includes: a transmission system 110 which combines a frequency-modulated signal generated by separating a transmission signal into a phase signal θ and an amplitude signal (r) and subjecting the phase signal θ to frequency modulation or orthogonal modulation with a signal generated by subjecting the amplitude signal (r) to amplitude modulation and transmits composite signal; a reception system 120 which orthogonally demodulates and outputs an orthogonally modulated reception signal; and a post-distorter 128 which acquires input/output characteristics of the reception system 120 with a reference signal generated by using the phase modulation system of the transmission system 110 in a non-communication state and compensates for nonlinear distortion caused by the reception system 120. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a communication device such as a portable terminal, and more particularly to a communication device that compensates for nonlinear distortion occurring in a reception system.

  Conventionally, in this type of communication apparatus, nonlinear distortion generally occurs in the transmission system, and the nonlinear distortion is compensated mainly in the transmission system.

  However, depending on the communication system, there is a case where it is necessary to compensate for nonlinear distortion generated in the reception system.

  That is, in this type of communication device, when the power supply voltage is lowered when the drain current of the receiving amplifier is constant, the output is lowered, and the nonlinear distortion characteristic and the dynamic range (D / L) are lowered.

  For this reason, for example, when it is desired to reduce the power supply voltage of the entire receiving system to increase the efficiency of the communication terminal, or when the power supply voltage tends to be reduced due to device miniaturization, nonlinear distortion is likely to occur. It is necessary to compensate for nonlinear distortion.

  Also, if AGC (Automatic Gain Control: a circuit that variably controls the gain of the amplifier so that the output signal level remains constant even if the input signal level changes) cannot fully follow the peak, the receiving system Therefore, it is necessary to compensate for nonlinear distortion.

  Furthermore, when multiple conditions overlap, such as when error correction becomes ineffective due to fading and non-linear distortion, it is necessary to compensate for non-linear distortion and enable error correction in the receiving system. .

Further, in this type of communication apparatus, the power supply voltage tends to be reduced due to the miniaturization of devices due to multimode, multiband, and high speed, so the range of the power supply voltage of the entire apparatus is narrowed and the device operating range is reduced. For,
(1) High-order distortion is likely to occur.
(2) Distortion characteristics tend to fluctuate due to temperature, power supply voltage fluctuations, and other slight complex environmental fluctuations.
(3) In addition to LNA (Low Noise Amplifier), a plurality of devices that operate nonlinearly, such as mixers and buffers, are generated.
The nonlinear characteristics are complicated.

  For this reason, in this type of communication apparatus, the variation in distortion characteristics in high order is particularly large, and it is not possible to cope with deterioration of nonlinear distortion characteristics only by compensating nonlinear distortion using a fixed table according to the environmental temperature.

  Therefore, in this type of communication apparatus, if the power supply voltage is reduced, it is likely that the distortion coefficient needs to be sequentially compensated as necessary due to environmental changes.

  Conventionally, as a technique for compensating for such nonlinear distortion, for example, those described in Patent Document 1 and Patent Document 2 are known.

  The technique described in Patent Document 1 uses a reverse distortion characteristic table calculated from a distortion characteristic and a temperature characteristic measured at the time of factory shipment or the like to estimate the reverse characteristic distortion in a distortion estimation unit and to deal with the generated nonlinear distortion. Nonlinear distortion is compensated by multiplying the inverse characteristic distortion by a multiplier after the nonlinear amplifier.

The technique described in Patent Document 2 is a predistortion method that generates an inverse characteristic of an amplifier before a non-linear amplifier and cancels distortion after the non-linear amplifier, and has a waveform signal that gradually increases to a predetermined amplitude value during training. In the training period, the waveform signal is repeatedly input, the amplitude is swept, and the distortion compensation coefficient is estimated within a predetermined amplitude value range.
JP 2001-339449 A JP 09-069733 A

  However, in the technique described in the above-mentioned conventional patent document 1, when a low voltage is assumed, not only an LNA but also a distortion characteristic of a plurality of nonlinear elements is assumed, or a temperature or a change with time of a detection circuit or the like is assumed. In some cases, an implementation method for estimating the distortion estimation unit from the actual distortion characteristics in the receiving system is necessary.

  Further, in the technique described in the above-mentioned conventional patent document 2, in the transmission system, the training signal can be generated only by changing the baseband signal. However, when the reference signal is generated in the reception system, another RF modulation system is required. The circuit scale increases.

  In addition, in order to perform accurate compensation, it is necessary to use a modulation signal as a reference signal and also consider frequency characteristics as input / output characteristics, and a configuration that easily realizes this is required.

  The present invention has been made in view of this point, and an object of the present invention is to provide a communication apparatus that can accurately compensate for nonlinear distortion of a receiving system without increasing the circuit scale.

  In order to solve such a problem, a communication apparatus according to the present invention has a transmission system for forming a transmission signal, a reception demodulation circuit including a nonlinear amplifier, a reception system for demodulating the reception signal, and the transmission system. A switch that inputs the transmission signal to the reception system; and a distortion compensation unit that compensates for non-linear distortion generated in the reception system using the transmission signal input via the switch as a reference signal. take.

  According to the present invention, it is possible to accurately compensate for nonlinear distortion of a receiving system without increasing the circuit scale. Further, by adding a minimum-reduction RF circuit to the reference signal generation circuit, it is possible to generate a CW, a modulated wave, an intermodulation distortion signal, and the like according to the application.

  Hereinafter, a receiving apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the component and equivalent part which have the same structure or function, and the description is not repeated.

(Embodiment 1)
The communication device according to Embodiment 1 of the present invention is configured to receive power by sweeping power with an attenuator using a reference signal generated by a phase modulation output of a polar modulation transmission system that performs phase modulation by quadrature modulation in a non-communication state It is characterized in that the distortion characteristic of the reception system is obtained by coupling to the input, and the reverse characteristic is added in the digital part before the nonlinear amplifier to improve the reception performance deterioration due to the nonlinear distortion.

  FIG. 1 is a block diagram showing a configuration of a communication apparatus according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the communication apparatus 100 of this example includes an antenna 101, a duplexer (DUP) 102, a transmission system 110, a reception system 120, and a tunable attenuator (ATT) 130.

  The transmission system 110 includes a transmission system baseband unit (BB) 111, a phase amplitude conversion unit 112, a quadrature modulation unit (MOD) 113, a transmission system oscillation unit 114, an amplitude amplification unit (EM) 115, a transmission system switch 116, an amplifier ( PA) 117.

  The reception system 120 includes a reception system switch 121, a detector 122, a low noise amplifier (LNA) 123, an auto gain controller (AGC) 124, a quadrature demodulation unit (DEMOD) 125, a reception system oscillation unit 126, and low-pass filters (LPF) 127a and 127b. , A post-distorter 128, and a receiving system baseband unit (BB) 129.

  In FIG. 1, the transmission system baseband unit 111 generates an I / Q signal and outputs the generated I / Q signal to the phase amplitude conversion unit 112.

  The phase / amplitude conversion unit 112 converts the I / Q signal input from the transmission system baseband unit 111 into the phase signals cos θ and sin θ and the amplitude signal r, and outputs the converted phase signals cos θ and sin θ to the quadrature modulation unit 113. In addition, the amplitude signal r is output to the amplitude amplifying unit 115.

  The amplitude amplification unit 115 amplifies the amplitude signal r input from the phase amplitude conversion unit 112 to an appropriate signal, and outputs the amplified amplitude signal r to the amplifier 117.

  When normal transmission is performed by the transmission system 110, the transmission system oscillation unit 114 outputs a transmission frequency to the quadrature modulation unit 113, and the transmission system 110 serves as a reference signal for compensating for nonlinear distortion generated in the reception system 120. When generating, the reception frequency of the reception system 120 is output to the orthogonal modulation unit 113.

  When normal transmission is performed by the transmission system 110, the quadrature modulation unit 113 performs quadrature modulation on the phase signals cos θ and sin θ input from the phase amplitude conversion unit 112 by the oscillation signal provided from the transmission system oscillation unit 114, and performs orthogonal The modulated frequency modulation signal is D / A converted and output to the transmission system switch 116.

  In addition, when the transmission system 110 generates a reference signal for compensating for nonlinear distortion generated in the reception system 120, the orthogonal modulation unit 113 outputs a CW signal having a reception frequency to the transmission system switch 116. However, the generation of the reference signal by the transmission system 110 is performed in a non-communication state such as during training or when an error occurs.

  The transmission system switch 116 is switched to the side that outputs the frequency modulation signal input from the quadrature modulation unit 113 to the amplifier 117 during transmission by the transmission system 110.

  In addition, the transmission system switch 116 outputs a reference signal, which is a CW signal of the reception frequency input from the quadrature modulation unit 113, to the tunable attenuator 130 when acquiring inverse characteristics for compensating for nonlinear distortion generated in the reception system 120. It is switched to the side to do.

  The amplifier 117 combines the amplitude signal r input from the amplitude amplifying unit 115 and the frequency modulation signal input from the quadrature modulation unit 113 via the transmission system switch 116 during transmission by the transmission system 110, and combines the combined transmission signal. Is output to the duplexer 102.

  The duplexer 102 transmits the transmission signal input from the amplifier 117 through the antenna 101.

  In addition, when transmitting by the TDD (Time Division Duplex) method in which the communication path is finely divided on the time axis and switching between transmission and reception at high speed, SPDT (single pole dual) that switches the differential signal filter according to the frequency band through) is used in place of the duplexer 102.

  The tunable attenuator 130 sweeps the power of the reference signal input from the quadrature modulation unit 113 via the transmission system switch 116 and acquires the ramp signal when acquiring the inverse characteristic for compensating for the nonlinear distortion generated in the reception system 120. The generated ramp signal is output to the reception system switch 121.

  The reception system switch 121 is switched to the side that outputs the ramp signal input from the tunable attenuator 130 to the low noise amplifier 123 and the detector 122 when acquiring reverse characteristics for compensating for nonlinear distortion generated in the reception system 120.

  Also, the reception system switch 121 is switched to the side that outputs the reception signal received by the antenna 101 and output from the duplexer 102 to the low noise amplifier 123 and the detector 122 when receiving by the reception system 120.

  The detector 122 detects the signal level of the received signal input from the duplexer 102 or the reference signal level input from the tunable attenuator 130 according to the switching of the reception system switch 121, and the detected result is the post-distorter 128. Output to.

  The low noise amplifier 123 amplifies the reception signal input from the duplexer 102 or the reference signal input from the tunable attenuator 130, adjusts the gain of the amplified signal by the auto gain controller 124, and outputs the amplified signal to the quadrature demodulation unit 125.

  The reception system oscillation unit 126 outputs an oscillation frequency corresponding to the reception channel to the quadrature demodulation unit 125.

  The quadrature demodulation unit 125 performs quadrature demodulation on the reception signal input from the auto gain controller 124 with the oscillation signal provided from the reception system oscillation unit 126 and outputs the quadrature demodulated reception signal to the post-distorter 128 through the low-pass filters 127a and 127b. To do.

  Based on the detection result of the detector 122, the post-distorter 128 multiplies the signal input from the quadrature demodulator 125 through the low-pass filters 127a and 127b to compensate for the non-linear distortion generated in the receiving system 120, thereby correcting the non-linear distortion. Is output to the receiving system baseband unit 129.

  Note that the post-distorter 128 has a memory function for temporarily storing what happens to the reference signal when the reference signal is input.

  Next, the operation of the reception system 110 of the communication apparatus 100 of this example will be described with reference to FIGS. FIG. 2 is a block diagram showing a configuration of a transmission system of the communication apparatus according to Embodiment 1 of the present invention. FIG. 3 is a diagram for explaining the output of each part of the transmission system of the communication apparatus according to Embodiment 1 of the present invention.

  2, when the transmission system 110 is used as a normal transmission means, the transmission system switch 116 is switched to the side that outputs the frequency modulation signal input from the quadrature modulation unit 113 to the amplifier 117, and the upper part of FIG. As shown, the transmission system oscillation unit 114 outputs the transmission frequency as the oscillation frequency.

  In this case, the phase / amplitude conversion unit 112 converts the I / Q signal input from the transmission system baseband unit 111 into the phase signals cos θ and sin θ and the amplitude signal r and outputs the converted signals.

  In this case, the amplitude modulation side of the amplitude amplification unit 115 is turned on to amplify the amplitude signal r input from the phase amplitude conversion unit 112 to an appropriate signal, and the amplified amplitude signal r is supplied to the power supply unit of the amplifier 117. Output to.

  Thereby, in this case, the PA output is output from the output port of the amplifier 117.

  As described above, when the transmission system 110 is used as a normal transmission unit, the transmission system 110 does not generate a reference signal and performs normal transmission.

  In addition, when transmitting by the above-mentioned TDD system, SPDT switches to the amplifier 117 side at the transmission timing.

  On the other hand, when the transmission system 110 is used as a reference signal generating means for compensating for nonlinear distortion generated in the reception system 120, the reference signal input from the quadrature modulation unit 113 is output to the tunable attenuator 130. The transmission system switch 116 is switched, and the transmission system oscillation unit 114 outputs the reception frequency (including other Ch (channel)) of the reception system 120 as the oscillation frequency as shown in the lower part of FIG.

  In this case, the phase / amplitude converter 112 receives the I / Q signal input from the transmission system baseband unit 111 as well as the 1/0 signal or the method for measuring the input / output characteristics of the amplifier 117. Output as an IQ signal.

  In this case, the amplitude modulation side of the amplitude amplification unit 115 is turned off so that the amplitude signal r input from the phase amplitude conversion unit 112 is not amplified.

  As a result, as an output of the quadrature modulation unit 113 that quadrature-modulates the reception modulation system IQ signal at the frequency when generating the reference signal, a CW signal (sine wave of a predetermined frequency) of the reception frequency passes through the transmission system switch 116. And output as a reference signal to the tunable attenuator 130 side.

  Normally, the non-linear distortion generated in the receiving system 120 can be compensated by the CW signal having the reception frequency generated as described above. However, the modulation signal is actually generated by the transmitting system 110 and output as a reference signal. If desired, an I / Q signal is output as a generation reference signal as a modulation wave of the reception frequency, as in normal quadrature modulation.

  Note that the oscillation frequency of the transmission system oscillation unit 114 at this time is set to the same value as the frequency of the CW signal of the reception system 120.

  In addition, when creating a modulated wave reference signal in this way, a test signal of a reception modulation method is prepared in advance in the memory of the transmission system baseband unit 111. Here, in the case of LTE, since the baseband (BB) parameters of OFDM and SC (single carrier) -FDMA are similar, it is easy to create a modulation signal of the reception system. In other words, in this case, the signal generation method is similar between upstream and downstream, and the same baseband parameters (clock frequency, sampling frequency, etc.) can be used, so that a modulated signal corresponding to the reception system 120 is transmitted by the transmission system 110. Easy to make.

  Next, a distortion compensation method in the communication apparatus 100 of this example will be described with reference to FIG. FIG. 4 is a block diagram showing a configuration of a reception system of the communication apparatus according to Embodiment 1 of the present invention.

  In FIG. 4, the tunable attenuator 130 receives the reference signal generated by the transmission system 110 via the transmission system switch 116 as described above.

  The tunable attenuator 130 sweeps the power of the reference signal input from the transmission system 110 via the transmission system switch 116 and acquires the distortion characteristic of the reception system 120, and receives the reception system 120 via the reception system switch 121. The reference signal is coupled to the input.

  The power variable range of the reference signal at the time of acquiring the reverse characteristic starts from the maximum level with large distortion, and is varied in a ramp shape by the tunable attenuator 130 until it is determined that the difference has entered the linear region.

  Further, the gain setting of the auto gain controller 124 at the time of acquiring the reverse characteristic is set to a value with the highest gain, that is, a state in which the distortion of the receiving system 120 is the largest. Then, the test signal with respect to the reference signal when the distortion of the reception system 120 is maximum is stored in the memory of the post-distorter 128 as a distortion compensation table.

  During distortion compensation of the receiving system 120, the peak that the auto gain controller 124 cannot follow is instantaneously compensated for distortion based on the distortion compensation table.

  Here, as shown in FIG. 5, the post-distorter 128 receives the input of the receiving system 120 from the detector information acquired by the level detection by the detector 122 and the information after A / D conversion output from the quadrature demodulation unit 125. Measure the output characteristics and calculate the inverse characteristics (noise and phase noise average the input and output curves to make the effect invisible).

  When the reception mode is set, the nonlinear distortion generated in the receiving system 120 is digitally multiplied by the inverse characteristic calculated by the postdistorter 128 to compensate for the distortion.

  However, such distortion compensation of the reception system 120 causes a decrease in the slew rate if it is always performed. For example, when the nonlinear distortion of the reception system increases and the reception state deteriorates, or the communication device 100 is turned on. Only during training.

  Further, the distortion compensation table stored in the memory of the postdistorter 128 is updated only when the compensation is not effective depending on the environment. Thereby, the data amount of the distortion compensation table can be reduced and the memory of the postdistorter 128 can be reduced.

  As described above, in the communication apparatus 100 of this example, distortion compensation is performed by canceling the nonlinear distortion generated in the receiving system 120 by the inverse characteristic calculated as described above in the short term.

  In the medium and long term, the signal level detection function of the reception system baseband unit 129 is used to perform distortion compensation in the same manner as in the past by a combination of the auto gain controller 124 and the reception system baseband unit 129.

  As described above, in the communication apparatus 100 of this example, a desired reference is used by using the transmission system 110 (a polar modulation transmission system that performs phase modulation by quadrature modulation) in a non-communication state such as during training or when an error occurs. Since the signal is generated, it is not necessary to provide a dedicated RF modulation system for generating the reference signal, and the circuit scale can be reduced.

  Further, since the communication apparatus 100 of this example uses a VCO based on multiband and multimode, the frequency can be easily varied.

  In addition, in the communication apparatus 100 of this example, the input / output characteristics for each frequency can be obtained using the modulation signal, so that even when the distortion characteristics have frequency characteristics, distortion compensation can be performed with higher accuracy. is there.

  In the embodiment of the present invention, the operation in the FDD system has been described. However, by replacing the DUP of the duplexer 102 with SPDT, it is possible to support a TDD receiver.

(Embodiment 2)
FIG. 6 is a block diagram showing a configuration of a communication apparatus according to Embodiment 2 of the present invention.

  As shown in FIG. 6, communication apparatus 200 of the present example uses quadrature modulation for phase modulation of transmission system 110 in communication apparatus 100 according to Embodiment 1 when the reference signal is only a CW signal and table accuracy is obtained. Instead of the polar modulation transmission system to be performed, a polar modulation transmission system for performing phase modulation by frequency modulation is used.

  That is, in the transmission system 210 of the communication apparatus 200 of the present example, the phase component and the amplitude component of the I / Q signal output from the transmission system baseband unit 111 are converted into the phase signal θ time derivative dθ / by the phase amplitude conversion unit 112. Using the amplitude signal r as a power source for the phase modulation amplifier (amplifier 117), the phase modulation signal phase-modulated by the transmission system oscillation unit 114 and the amplitude modulation amplified by the amplitude amplification unit 115 are separated. Modulation synthesis with the signal is performed.

  On the other hand, in the reception system 220 of the communication apparatus 200 of this example, the output of the low noise amplifier 123 and the output of the synthesizer 201 are multiplied by the multiplier 202 and input to the quadrature demodulation unit 125. Note that only the reception system 120 in the first embodiment may be replaced with the configuration of the reception system 220 in the second embodiment.

  As described above, in the communication apparatus 200 of this example, as in the case of the communication apparatus 100 according to the first embodiment, when the transmission system 210 is in a non-communication state, such as during training or when an error occurs, Since a desired reference signal can be generated using a polar modulation system, it is not necessary to provide a dedicated RF modulation system for generating the reference signal, and the circuit scale can be reduced.

(Embodiment 3)
FIG. 7 is a block diagram showing a configuration of a communication apparatus according to Embodiment 3 of the present invention.

  As shown in FIG. 7, the communication apparatus 300 of this example uses a polar modulation system such as diversity transmission in a communication system capable of switching between MIMO and non-MIMO, and generates a reference signal that is not used during non-MIMO. The transmission system 310 is configured.

  That is, the communication apparatus 300 of this example has a configuration including two transmission systems 210 and reception systems 220 of the communication apparatus 200 according to the second embodiment.

  In FIG. 7, the transmission system and reception system of the first system are shown by adding a symbol A to each part, and the transmission system and reception system of the second system are shown by adding a code B to each part. The description of each part is omitted.

  As described above, in communication apparatuses 100, 200, and 300 according to the embodiments, when the transmission system is in a non-communication state or a non-use state, the reference generated by the phase modulation output or polar modulation of the EER transmission system The distortion characteristic of the receiving system is acquired by sweeping the power using the tunable attenuator 130 and coupling the signal to the receiving system input.

  In communication apparatuses 100, 200, and 300 according to each embodiment, the inverse characteristic acquired using the transmission system is added by the digital unit in front of the nonlinear amplifier, thereby degrading the reception performance due to the nonlinear distortion of the reception system. To improve.

  Therefore, in the communication apparatuses 100, 200, and 300 according to the respective embodiments, a post-distortion system capable of changing the frequency and the reference signal can be easily realized with a minimum circuit addition.

  Further, in communication apparatuses 100, 200, and 300 according to the respective embodiments, it is possible to increase the accuracy of the input / output characteristic curve by obtaining the input / output characteristics by the modulated wave for each frequency, so that multiband, multiband It becomes possible to support modes, multiple branches, and the like.

  Moreover, in the communication apparatuses 100, 200, and 300 according to each embodiment, the distortion compensation table is updated only when necessary, so that the memory of the postdistorter 128 can be reduced.

  Moreover, in the communication devices 100, 200, and 300 according to the embodiments, since the input / output characteristics of the actual circuit are acquired, it is possible to cope with higher-order distortion.

  Moreover, in the communication apparatuses 100, 200, and 300 according to each embodiment, the error is acquired before distortion compensation and the input / output characteristics are averaged, so that distortion is added to the signal including noise and fading, Only distortion is removed by the post-distortion circuit, and it is less susceptible to noise and fading.

  Note that the distortion compensation technique according to the present invention can also be applied as a distortion compensation technique for portable terminals and base stations.

  In addition, the distortion compensation technique according to the present invention can compensate for distortion even when the reception system of the communication apparatus is in another band or in another mode.

  The communication apparatus according to the present invention can compensate for nonlinear distortion in the reception system with high accuracy without increasing the circuit scale, and is therefore useful as a communication apparatus that compensates for nonlinear distortion generated in the reception system.

The block diagram which shows the structure of the communication apparatus which concerns on Embodiment 1 of this invention. The block diagram which shows the structure of the transmission system of the communication apparatus which concerns on Embodiment 1 of this invention. The figure for demonstrating the output of each part of the transmission system of the communication apparatus which concerns on Embodiment 1 of this invention. The block diagram which shows the structure of the receiving system of the communication apparatus which concerns on Embodiment 1 of this invention. The graph which shows the relationship between the detector information acquired by the level detection by the detector of the communication apparatus which concerns on Embodiment 1 of this invention, and the information after A / D conversion output from a quadrature demodulator The block diagram which shows the structure of the communication apparatus which concerns on Embodiment 2 of this invention. The block diagram which shows the structure of the communication apparatus which concerns on Embodiment 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100,200,300 Communication apparatus 101 Antenna 102 Duplexer 110,210 Transmission system 111 Transmission system baseband part 112 Phase amplitude conversion part 113 Orthogonal modulation part 114 Transmission system oscillation part 115 Amplitude amplification part 116 Transmission system switch 117 Amplifier 120,220 Reception system 121 Reception system switch 122 Detector 123 Low noise amplifier 124 Auto gain controller 125 Quadrature demodulation unit 126 Reception system oscillation unit 127a, 127b Low pass filter 128 Post-distorter 129 Reception system baseband unit 201 Synthesizer 202 Multiplier

Claims (7)

A transmission system for forming a transmission signal;
A receiving system having a receiving demodulation circuit including a non-linear amplifier and demodulating a received signal;
A switch for inputting the transmission signal obtained by the transmission system to the reception system;
A distortion compensation unit that compensates for nonlinear distortion generated in the reception system using the transmission signal input via the switch as a reference signal. The communication apparatus according to claim 1, wherein the transmission system includes a polar modulation system that performs phase modulation by quadrature modulation. The communication apparatus according to claim 1, wherein the transmission system includes a polar modulation system that performs phase modulation by frequency modulation. The communication apparatus according to claim 1, wherein the transmission signal input to the reception system via the switch is a radio frequency transmission signal. The communication device according to claim 1, wherein the switch causes the transmission signal to be input to the reception system in a non-communication state. The communication device according to claim 5, wherein the switch inputs a signal of a MIMO transmission branch in a non-communication state to the reception system. The distortion compensation unit includes a storage unit that stores a distortion compensation table for compensating for nonlinear distortion generated in the reception system, and updates the distortion compensation table only when compensation does not work due to an environment. The communication apparatus according to claim 6.

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