JP2020027966A - Radio communication device and received signal correcting method - Google Patents

Abstract

To provide a radio communication device and a received signal correcting method, capable of suppressing deterioration in reception performance caused by gain difference or phase difference between a plurality of receiving circuits.SOLUTION: A receiving circuit 20 receives a radio signal through the corresponding antenna 40. Correction signal adding means 21 adds a correction signal of a prescribed frequency in a frequency band of received signal to the received signal. Correction signal extracting means 22 extracts the correction signal from the received signal to which the correction signal is added, and outputs the extracted correction signal to correction parameter calculating means 30. The correction parameter calculating means 30 generates correction parameters of the received signal on the basis of the correction signal input from the correction signal extracting means 22 of each receiving circuit 20. Correcting means 23 of each receiving circuit 20 corrects at least one of an amplitude and a phase of the receiving signal according to the correction parameters calculated by the correction parameter calculating means 30.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a wireless communication device and a received signal correction method, and more particularly, to a wireless communication device that receives a plurality of wireless signals through a plurality of antennas, and a received signal correction method in such a wireless communication device.

  2. Description of the Related Art In recent years, in the field of mobile communication, a wireless device that includes a plurality of transceivers and supports a multiple-input and multiple-output (MIMO) function is becoming popular. Furthermore, in the fifth generation mobile communication system (5G: 5th Generation), which is expected to be commercially used in the future, adoption of the Massive-MIMO technology using a large number of transceivers is being studied.

  In a wireless device having a MIMO function, beamforming may be performed in order to provide directivity to the propagation direction of a radio wave and increase the use efficiency of the radio wave. In a wireless device that performs beamforming, if the gains and phases of the transceivers are different, beamforming cannot be performed accurately. In order to perform beamforming accurately, it is necessary to match the gain and phase of each transceiver.

  Here, Patent Literature 1 discloses a diversity receiving apparatus that receives a signal modulated by a single carrier using a plurality of receiving antennas, and selects or combines the plurality of received signals. The diversity receiver described in Patent Literature 1 multiplexes a reference signal (pilot signal) into a reception signal output from each reception antenna. The frequency of the pilot signal is set to a frequency outside the frequency band of the received signal. Patent Document 1 describes estimating the level of a received signal output from each receiving antenna using a pilot signal, estimating the amount of attenuation of the received signal, and the like.

JP 2003-174390 A

  In a wireless device including a plurality of receiving circuits, it is necessary to estimate a phase error between the plurality of receiving circuits in order to obtain a highly accurate received signal. However, Patent Document 1 focuses only on the adjustment of the received power (gain), and does not describe estimating the phase error. In Patent Document 1, a pilot signal is multiplexed outside the frequency band of a received signal. In this case, a narrow-band filter cannot be used in the receiving circuit except for a band-pass filter arranged immediately after the antenna. For this reason, there is a problem that the reception performance is degraded if there is an interfering wave with a strong power or an interfering wave near the frequency band of the received signal that cannot be completely removed by the band-pass filter disposed immediately after the antenna. .

  The present disclosure has been made in view of the above circumstances, and in a wireless communication apparatus having a plurality of receiving circuits, a wireless communication apparatus and a received signal correction method capable of suppressing deterioration of reception performance due to a gain difference and a phase difference between the plurality of receiving circuits. The purpose is to provide.

  In order to solve the above-described problems, the present disclosure has a plurality of receiving circuits each receiving a radio signal through a corresponding antenna, and calculates at least one of a gain and a phase shift between the plurality of receiving circuits. Correction parameter calculation means for generating a correction parameter of the received signal in each receiving circuit based on the calculated shift, wherein the plurality of receiving circuits each receive a signal of a predetermined frequency within a frequency band of the received signal. Correction signal adding means for adding a correction signal; correction signal extracting means for extracting the correction signal from the received signal to which the correction signal has been added and outputting the signal to the correction parameter calculating means; Correction means for correcting at least one of the amplitude and the phase of the received signal in accordance with the correction parameter calculated by the calculation means, Parameter calculating means provides a wireless communication device for calculating at least one of the deviation of the gain and phase between the plurality of reception circuits based on the correction signal input from the receiving circuit via the correction signal extraction means.

  The present disclosure also receives a plurality of wireless signals through a plurality of antennas, and adds a correction signal of a predetermined frequency within a frequency band of the received signal to each of the plurality of received signals, wherein the correction is performed. The signal for correction is extracted from each of the plurality of received signals to which the signals for addition are added, and based on the signal for correction extracted from the plurality of received signals, a plurality of reception circuits for receiving the plurality of wireless signals are provided. Calculating a shift of at least one of the gain and the phase of the received signal, generating a correction parameter of the received signal in each receiving circuit based on the calculated shift, at least one of the amplitude and the phase of the received signal according to the calculated correction parameter. And a method for correcting a received signal.

  The wireless communication device and the received signal correction method according to the present disclosure can suppress deterioration of reception performance due to a gain difference and a phase difference between a plurality of receiving circuits in a wireless communication device having a plurality of receiving circuits.

1 is a block diagram illustrating a schematic configuration of a wireless communication device according to the present disclosure. FIG. 1 is a block diagram illustrating a wireless communication device according to a first embodiment of the present disclosure. The figure which shows the spectrum of a received signal. The figure which shows the passing characteristic of LPF. FIGS. 5A and 5B are diagrams illustrating spectra of a baseband signal to which a correction signal is not added and a baseband signal to which a correction signal is added. FIG. 7 is a block diagram illustrating a configuration of a wireless communication device according to a second embodiment of the present disclosure. 7A is a diagram illustrating a spectrum of a radio signal, and FIG. 7B is a diagram illustrating a spectrum of a correction signal.

  Prior to the description of the embodiments of the present disclosure, an overview of the present disclosure will be described. FIG. 1 schematically illustrates a wireless communication device according to the present disclosure. The wireless communication device 10 includes a plurality of receiving circuits 20 and a correction parameter calculating unit 30. Each receiving circuit 20 includes a correction signal adding unit 21, a correction signal extracting unit 22, and a correcting unit 23.

  The plurality of receiving circuits 20 receive radio signals through the corresponding antennas 40, respectively. The correction signal adding means 21 adds a correction signal of a predetermined frequency within a frequency band of the received signal to the received signal. The correction signal extracting means 22 extracts a correction signal from the received signal to which the correction signal has been added. The correction signal extraction unit 22 outputs the extracted correction signal to the correction parameter calculation unit 30. The correction parameter calculation means 30 receives the correction signal extracted in each reception circuit 20 from the correction signal extraction means 22 of each reception circuit 20.

  The correction parameter calculating means 30 calculates at least one of a gain and a phase shift between the plurality of receiving circuits 20 based on the correcting signal input from the correcting signal extracting means 22 of each receiving circuit 20. The correction parameter calculation means 30 generates a correction parameter of the received signal in each receiving circuit 20 based on at least one of the calculated gain and phase. The correction unit 23 of each reception circuit 20 corrects at least one of the amplitude and the phase of the received signal according to the correction parameter calculated by the correction parameter calculation unit 30.

  In the present disclosure, a signal of a predetermined frequency within the frequency band of the received signal is used as the correction signal added to the received signal in the receiving circuit 20. In this case, even if a narrow band filter that cuts out a signal component outside the frequency band of the received signal is arranged between the correction signal adding means 21 and the correction signal extracting means 22, Can extract a correction signal. For this reason, the radio communication device 10 according to the present disclosure can suppress deterioration of the reception performance even when an interfering wave exists, unlike the device described in Patent Literature 1 in which a pilot signal having a frequency outside the signal band is used. It is. Therefore, in the present disclosure, it is possible to calculate at least one of the gain and the phase shift between the plurality of reception circuits 20 while suppressing the influence of the reception signal on the reception performance.

  Further, in the present disclosure, in each reception circuit 20, the correction unit 23 corrects at least one of the amplitude and the phase of the received signal according to the correction parameter calculated by the correction parameter calculation unit 30. By doing so, it is possible to make at least one of the amplitude and the phase of the reception signal output from each reception circuit 20 uniform, and to suppress the deterioration of the reception performance due to the gain difference and the phase difference between the plurality of reception circuits 20. can do. The gain difference and the phase difference of the receiving circuit 20 may change during operation of the device. The wireless communication device 10 according to the present disclosure can calculate at least one of the gain and the phase shift between the plurality of receiving circuits 20 while receiving a wireless signal, and can reduce the influence on the reception accuracy while reducing the gain. And the phase error can be calibrated.

  Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. FIG. 2 illustrates a wireless communication device according to the first embodiment of the present disclosure. The wireless communication apparatus 100 sets N antennas 101-1 to 101-N, a local oscillator 102 for a correction signal, a local oscillator 103 for an IF (Intermediate Frequency) signal, and a BB (Base Band) signal, where N is an integer of 2 or more. It has a local oscillator 104, N LPFs (Low Pass Filters) 105-1 to 105-N, a correction parameter calculator 106, a reception signal processing unit 107, and N reception circuits 110-1 to 110-N.

  Assuming that n is an integer of 1 or more and N or less, the receiving circuit 110-n includes a BPF (Band Pass Filter) 111-n, an adder 112-n, an LNA (Low Noise Amplifier) 113-n, and a multiplier (Mixer) 114-. n, a BPF 115-n, an ADC (Analog to Digital Converter) 116-n, a multiplier 117-n, an LPF 118-n, a corrector 120-n, and a correction signal removing unit 121-n.

  In the following description, when it is not necessary to distinguish them, the antennas 101-1 to 101-N, the LPFs 105-1 to 105-N, and the receiving circuits 110-1 to 110-N are simply the antenna 101, Also referred to as the LPF 105 and the receiving circuit 110. The same applies to each element in the receiving circuit 110. FIG. 2 shows a configuration of a portion mainly used for receiving a wireless signal in wireless communication apparatus 100. The wireless communication device 100 may include components such as a demodulator. The wireless communication device 100 may further include a transmission circuit for transmitting a wireless signal.

  In the present embodiment, the wireless communication apparatus 100 receives a wireless signal of a wireless standard whose modulation scheme is OFDM (Orthogonal Frequency Division Multiplexing) and whose center subcarrier is not used. For example, the wireless communication device 100 receives a wireless signal according to a communication standard such as LTE (Long Term Evolution) and WiMAX (Worldwide Interoperability for Microwave Access). In the present embodiment, it is assumed that the receiving circuit 110 is configured as an IF conversion type receiving circuit. The IF conversion method is a method that uses an IF signal obtained by down-converting an RF (Radio Frequency) band received signal to an intermediate frequency.

  Each receiving circuit 110 receives a radio signal through the corresponding antenna 101. The antenna 101 corresponds to the antenna 40 in FIG. 1, and the receiving circuit 110 corresponds to the receiving circuit 20 in FIG. The BPF 111 passes a signal component in a signal band of a received wireless signal (received signal) and suppresses a signal component outside the signal band. That is, the BPF 111 removes a signal outside the signal band from the received signal.

  The adder 112 adds the local oscillation signal (correction signal) output from the correction signal local oscillator 102 to the reception signal from which the signal outside the signal band output from the BPF 111 is removed. In the present embodiment, the correction signal local oscillator 102 outputs a CW (Continuous Wave) signal having the same frequency as the carrier frequency of the received signal as a correction signal. The correction signal generated by the correction signal local oscillator 102 is distributed to the plurality of receiving circuits 110-1 to 110-N, and is input to the adders 112 of the receiving circuits 110. The adder 112 corresponds to the correction signal adding means 21 of FIG.

  FIG. 3 shows the spectrum of the received signal. In FIG. 3, the horizontal axis represents frequency. As shown in FIG. 3, the OFDM signal includes a plurality of subcarriers. The center subcarrier among the plurality of subcarriers is not used for data transmission, and therefore, the received signal does not include the component of the center subcarrier. When a correction signal having the same frequency as the carrier frequency is added to such a received signal, the correction signal is added at the center of the received signal, that is, at the frequency position of the center subcarrier. When the center subcarrier is not used for data transmission, the effect of the correction signal on the received signal is sufficiently small.

  Returning to FIG. 2, the LNA 113 amplifies the received signal to which the correction signal has been added. Multiplier 114 multiplies the received signal to which the correction signal is added by the local oscillation signal output from IF signal local oscillator 103, and down-converts the received signal into an IF signal. The local oscillation signal output from the IF signal local oscillator 103 is distributed to the plurality of receiving circuits 110-1 to 110 -N, and is input to the multiplier 114 of each receiving circuit 110. The IF signal local oscillator 103 and the multiplier 114 constitute an intermediate frequency signal converting means for converting the received signal to which the correction signal has been added into an intermediate frequency signal.

  The BPF 115 is an analog filter that limits the band of the received signal converted to the IF signal. The BPF 115 passes a signal component in the signal band of the IF signal and suppresses a signal component outside the signal band. That is, the BPF 115 removes an unnecessary signal from the IF signal. The ADC 116 converts the band-limited IF signal from an analog signal to a digital signal.

  Multiplier 117 multiplies the IF signal converted into a digital signal by the local oscillation signal output from local oscillator 104 for BB signal, and converts the IF signal into a baseband signal. The local oscillation signal output from the BB signal local oscillator 104 is distributed to the plurality of receiving circuits 110-1 to 110 -N, and is input to the multiplier 117 of each receiving circuit 110. Since the IF signal input to the multiplier 117 is a digital signal, the local oscillator for BB signal 104 and the multiplier 117 are implemented as digital circuits. The local oscillator for BB signal 104 and the multiplier 117 constitute a baseband conversion unit.

  The baseband signal converted by the multiplier 117 of each receiving circuit 110 is divided into two, and one is input to the LPF 105 and the other is input to the LPF 118. LPF 105 is arranged corresponding to each receiving circuit 110. The LPF 105 passes a signal component having a frequency equal to or lower than a predetermined frequency of the baseband signal and suppresses a signal component having a frequency higher than the predetermined frequency, thereby extracting a correction signal included in the baseband signal. On the other hand, the LPF 118 of each receiving circuit 110 removes an unnecessary signal from the baseband signal by passing a signal component having a frequency lower than a predetermined frequency of the baseband signal and suppressing a signal component having a frequency higher than the predetermined frequency. The LPF 105 corresponds to the correction signal extracting unit 22 in FIG.

  FIG. 4 shows the pass characteristics of the LPFs 105 and 118. In FIG. 4, the horizontal axis represents frequency. The position of the carrier frequency in the received signal shown in FIG. 3 corresponds to the frequency position “0” in the baseband signal. The LPF 105 has a narrow passband A that extracts only a DC (Direct Current) component in a baseband signal. The pass bandwidth of the LPF 105 is set to, for example, a width of one subcarrier. By using the LPF 105 having such a pass band A, a correction signal can be extracted from a baseband signal. On the other hand, the LPF 118 has a wide passband B corresponding to the bandwidth of the baseband signal. By using the LPF 118 having such a pass band B, unnecessary waves outside the signal band can be removed from the baseband signal.

  Returning to FIG. 2 again, the LPF 105 outputs the extracted correction signal to the correction parameter calculator 106. The correction parameter calculator 106 acquires the extracted correction signals from the plurality of receiving circuits 110-1 to 110-N. The correction parameter calculator 106 compares the correction signals obtained from each of the receiving circuits 110 and calculates a gain difference and a phase difference of each of the receiving circuits 110. The correction parameter calculator 106 determines a correction parameter in the corrector 120 of each receiving circuit 110 based on the calculated gain difference and phase difference. The correction parameter calculator 106 corresponds to the correction parameter calculator 30 in FIG.

  The correction parameter calculator 106 may include, for example, a processor and a memory, and may execute a process in accordance with a program read from the memory by the processor, thereby performing comparison of correction signals, determination of a correction parameter, and the like. Alternatively, the function of the correction parameter calculator 106 may be realized using a semiconductor processing device such as an ASIC (Application Specific Integrated Circuit) or a programmable device such as an FPGA (field-programmable gate array).

  The correction parameter calculator 106 notifies the corrector 120 of each receiving circuit 110 of the correction parameter. The corrector 120 corrects the amplitude and phase of the baseband signal from which the unnecessary signal output from the LPF 118 has been removed. The compensator 120 includes, for example, a variable amplifier and a variable phase shifter. The corrector 120 controls the gain of the variable amplifier and the amount of phase rotation given by the variable phase shifter according to the correction parameter notified from the correction parameter calculator 106. The corrector 120 corresponds to the correcting means 23 in FIG.

  The correction signal removal unit (correction signal removal means) 121 removes the correction signal from the baseband signal corrected by the corrector 120. The correction signal removing unit 121 removes the correction signal from the baseband signal based on the correction signal extracted by the LPF 105 and the correction parameter determined by the correction parameter calculator 106. When the power of the correction signal is sufficiently low compared to the power of each subcarrier used for data transmission, and the influence of the correction signal on data reception can be ignored, the correction signal removing unit 121 is omitted. Is also good.

  The reception signal processing unit 107 performs predetermined signal processing on a plurality of reception signals received by the plurality of reception circuits 110-1 to 110-N. The signal processing performed by the received signal processing unit 107 includes, for example, a process of combining received signals for beamforming. In each receiving circuit 110, the gain difference and the phase difference among the plurality of receiving circuits 110-1 to 110-N are corrected by using the corrector 120, so that the received signal processing unit 107 does not perform the correction. Thus, a signal having a high signal-to-noise ratio can be obtained.

  It is not necessary for the correction parameter calculator 106 to always calculate the correction parameters. The correction parameter calculator 106 may calculate the correction parameter, for example, when the power is turned on or when the environmental temperature or the like changes greatly. During the period when the correction parameter is not calculated by the correction parameter calculator 106, the local oscillator for correction signal 102 may not output the correction signal. In that case, the correction signal is not added to the received signal during the period when the correction parameter is not calculated. In a period in which the correction parameter calculator 106 does not calculate the correction parameter, the corrector 120 may correct the received signal using the correction parameter obtained in the previous calculation.

上記式（１）において、Ｓ_ＲＸｎ（ｔ）は、受信信号の変調成分を表す。本実施形態では、Ｓ_ＲＸｎ（ｔ）は、中心サブキャリア（ＤＣサブキャリア）が使用されていないＯＦＤＭ信号を表す。また、上記式（１）において、ｆ_ＲＦは搬送波周波数を表し、ｊは虚数を表し、ｔは時間を表す。 Hereinafter, the operation of the n-th receiving circuit 110-n will be described in detail on behalf of the plurality of receiving circuits 110-1 to 110-N. The receiving circuit 110-n receives a radio signal via the antenna 101-n. In the receiving circuit 110-n, the received signal S _RFn (t) from which unnecessary waves have been removed by the BPF 111-n is ideally represented by the following equation (1).

In the above equation (1), S _RXn (t) represents a modulation component of the received signal. In the present embodiment, S _RXn (t) represents an OFDM signal in which the center subcarrier (DC subcarrier) is not used. In the above formula (1), f _RF represents a carrier frequency, j represents an imaginary number, and t represents time.

補正用信号は、周波数が受信信号の搬送波周波数と同じＣＷ信号であり、上記式（２）において、右辺の第二項が補正用信号を表している。例えば、複数の受信回路１１０−１〜１１０−Ｎのそれぞれには、一定の振幅Ａ及び位相θの補正用信号が供給される。補正用信号の振幅及び位相は、差が既知であるならば、複数の受信回路１１０−１〜１１０−Ｎ間で異なっていてもよい。補正用信号が加算された受信信号Ｓ_{ＲＦｎ＋ＣＡＬ}（ｔ）は、上記式（１）と上記式（２）とを用いて、下記式（３）で表すことができる。

The received signal S _{RFn + CAL} (t) to which the correction signal output from the correction signal local oscillator 102 is added by the adder 112-n is represented by the following equation (2).

The correction signal is a CW signal having the same frequency as the carrier frequency of the received signal, and in the above equation (2), the second term on the right side represents the correction signal. For example, a correction signal having a constant amplitude A and a constant phase θ is supplied to each of the plurality of receiving circuits 110-1 to 110-N. The amplitude and the phase of the correction signal may be different among the plurality of receiving circuits 110-1 to 110-N as long as the difference is known. The reception signal S _{RFn + CAL} (t) to which the correction signal has been added can be expressed by the following equation (3) using the above equations (1) and (2).

上記式（４）において、Ｇ_ｎ及びφ_ｎは、それぞれ受信回路１１０−ｎのゲイン及び位相である。ｆ_ＩＦは、ＩＦ信号の周波数であり、ｆ_ＬＯは、補正信号用局部発振器１０２が出力する補正用信号の周波数である。ｆ_ＩＦとｆ_ＬＯとは、ｆ_ＩＦ＝ｆ_ＲＦ−ｆ_ＬＯの関係を持つ。 The received signal S _{RFn + CAL} (t) to which the correction signal has been added is amplified by the LNA 113-n, and is multiplied by the local oscillation signal output from the IF signal local oscillator 103 by the multiplier 114-n, thereby obtaining an intermediate frequency. It is converted to an IF signal of the band. The IF signal S _IFn (t) from which the unnecessary signal has been removed by the BPF 115-n is represented by the following equation (4).

In the above equation (4), G _n and φ _n are the gain and phase of the receiving circuit 110-n, respectively. f _IF is the frequency of the IF signal, and f _LO is the frequency of the correction signal output by the correction signal local oscillator 102. f _IF and f _LO have a relationship of f _IF = f _RF −f _LO .

上記式（５）において、ｅ＾（−ｊ２πｆ_ＩＦｔ）は、ＢＢ信号用局部発振器１０４が出力する局部発振信号（ＣＷ信号）を表す。ベースバンド信号への変換処理はデジタル回路で実施されるため、ダウンコンバートにおける各受信回路１１０でのゲイン差、及び位相差は無視できる。仮に、ベースバンド信号へのダウンコンバートにおいてゲイン差、及び位相差があった場合でも、アナログ回路領域でのゲイン差及び位相差と共に、包括的に算出可能である。 The IF signal S _IFn (t) is converted into a digital signal by the ADC 116-n, and is digitally down-converted by the multiplier 117-n. The baseband signal S _BBn (t) obtained by down-conversion can be represented by the following equation (5).

In the above equation (5), e ＾ (− j2πf _IF t) represents a local oscillation signal (CW signal) output from the local oscillator 104 for BB signal. Since the conversion process to the baseband signal is performed by the digital circuit, the gain difference and the phase difference in each receiving circuit 110 in the down-conversion can be ignored. Even if there is a gain difference and a phase difference in the down-conversion to the baseband signal, it can be comprehensively calculated together with the gain difference and the phase difference in the analog circuit area.

  FIGS. 5A and 5B show spectra of the baseband signal to which the correction signal has not been added and the baseband signal to which the correction signal has been added. 5A and 5B, the horizontal axis represents frequency, and the vertical axis represents power. FIG. 5A shows the spectrum of the baseband signal to which the correction signal has not been added, and FIG. 5B shows the spectrum of the baseband signal to which the correction signal has been added. In FIGS. 5A and 5B, a signal having a band of 20 MHz for LTE DL (Down Link) is used as a received signal.

  Referring to FIG. 5 (a), when the correction signal is not added, the center subcarrier is not used for data transmission (see also FIG. 3), and therefore, a decrease in the spectrum is observed around the frequency of 0 MHz of the baseband signal. On the other hand, when the correction signal is added, the correction signal is added to the frequency position of the center subcarrier, and as shown in FIG. Spectrum appears. The power of the correction signal is arbitrary, and may be higher or lower than the power of the subcarrier used for data transmission.

上記式（６）は、ＬＰＦ１０５−ｎにおいて、変調成分Ｓ_ＲＸｎ（ｔ）が完全に除去される理想的な場合を表している。補正パラメータ計算機１０６に入力される信号Ｓ_ＣＡＬｎ（ｔ）には、補正パラメータの計算に影響を与えない範囲で、変調成分Ｓ_ＲＸｎ（ｔ）の一部が含まれていてもよい。別の言い方をすると、ＬＰＦ１０５−ｎの通過帯域は、中心サブキャリアの周波数成分のみを通過させる通過帯域である必要はなく、通過帯域に周辺のサブキャリアの一部が含まれていてもよい。 The baseband signal S _BBn (t) is distributed to two LPFs 105-n and LPFs 118-n. The LPF 105-n has a narrow band pass characteristic (see also FIG. 4), and removes the modulation component S _RXn (t) of the received signal from the baseband signal S _BBn (t). The signal S _CALn (t) input to the correction parameter calculator 106 through the LPF 105-n can be represented by the following equation (6).

The above equation (6) represents an ideal case where the modulation component S _RXn (t) is completely removed in the LPF 105-n. The signal S _CALn (t) input to the correction parameter calculator 106 may include a part of the modulation component S _RXn (t) within a range that does not affect the calculation of the correction parameter. In other words, the passband of the LPF 105-n does not need to be a passband that allows only the frequency component of the center subcarrier to pass, and the passband may include a part of the surrounding subcarriers.

上記式（７）におけるＧ_ｎ／Ｇ_１は、受信回路１１０−１と受信回路１１０−ｎとのゲイン差を示す。また、φ_ｎ−φ_１は、受信回路１１０−１と受信回路１１０−ｎとの位相差を示す。 Correction parameter calculator 106, a plurality of reception circuits 110-1 to 110-N, to obtain a signal _{S CAL1 (t) ~S CALN (} t). Correction parameter calculator 106, by comparing the signal _{S CAL1 (t) ~S CALN (} t), calculates the gain difference and the phase difference between a plurality of reception circuits 110-1 to 110-N. For example, the ratio of the correction parameter calculator 106, a reference signal _{S CAL1} inputted from the receiving circuit 110-1 (t), the signal _S CAL2 _{(t) to S CALN} (t), signal _{S CAL1} and (t) Is calculated. In this manner, the gain difference and the phase difference between the reference receiving circuit 110-1 and each of the receiving circuits 110-2 to 110-N can be calculated. For example, the gain difference and the phase difference between the receiving circuit 110-1 and the receiving circuit 110-n can be calculated by the following equation (7).

G _n / G ₁ in the above equation (7) indicates a gain difference between the receiving circuit 110-1 and the receiving circuit 110-n. Φ _n −φ ₁ indicates a phase difference between the receiving circuit 110-1 and the receiving circuit 110-n.

上記したようにベースバンド信号Ｓ_ＢＢｎ（ｔ）を補正することで、ｎ番目の受信回路１１０−ｎのゲインＧ_ｎ及び位相φ_ｎを、それぞれ、基準とした１番目の受信回路１１０−１のゲインＧ_１及び位相φ_１に合わせることができる。 On the other hand, the other distributed baseband signal S _BBn (t) is input to the LPF 118-n. The LPF 118-n removes unnecessary signals outside the signal band from the baseband signal S _BBn (t). Correction parameters for amplitude and phase are input from the correction parameter calculator 106 to the corrector 120-n. The corrector 120 corrects the amplitude and phase of the baseband signal S _BBn (t) according to the correction parameters. The corrected baseband signal S ′ _BBn (t) can be expressed by the following equation (8).

By correcting the baseband signal S _BBn (t) as described above, the gain G _n and the phase φ _n of the _n -th receiving circuit 110-n are respectively used as the reference for the first receiving circuit 110-1. it can be adjusted to gain _{G 1} and the phase phi _1.

複数の受信回路１１０−１〜１１０−Ｎにおいて、上記した処理を行うことで、各受信回路１１０から、１番目の受信回路１１０−１と等しいゲイン及び位相の信号を得ることができる。 Referring now to the equation (8), the baseband signal S _'BBn corrected (t) is found to component _{Ae ^ jθ · G 1 e ^} jφ 1 of the correction signal remains . This component is equal to the correction signal S _CAL1 (t) obtained for the first receiving circuit 110-1 in the same manner as in the above equation (6). Correction signal removing unit 121-n from the baseband signal S _'BBn corrected (t), by subtracting the correction signal _{S CAL1} (t), removing the compensation signal from the baseband signal. The baseband signal S ″ _BBn (t) from which the correction signal has been removed by the correction signal removal unit 121-n can be expressed by the following equation (9).

By performing the above-described processing in the plurality of receiving circuits 110-1 to 110-N, signals having the same gain and phase as those of the first receiving circuit 110-1 can be obtained from each of the receiving circuits 110.

  In the present embodiment, each receiving circuit 110 adds a correction signal to a received signal. The received signal to which the correction signal has been added is down-converted to an IF signal by a multiplier 114, converted to a digital signal by an ADC 116, and converted to a baseband signal by a multiplier 117. LPF 105 extracts a correction signal from the converted baseband signal, and outputs the extracted correction signal to correction parameter calculator 106. By comparing the correction signals extracted by the respective receiving circuits 110 with the correction parameter calculator 106, the gain and phase characteristics of each of the receiving circuits 110 can be obtained, and the gain difference between the plurality of receiving circuits and A correction parameter for correcting the phase difference is obtained.

  In the present embodiment, the corrector 120 of each receiving circuit 110 corrects the received signal according to the correction parameters obtained by the correction parameter calculator 106. By doing so, the gain and the phase can be matched by the plurality of receiving circuits 110-1 to 110-N, and the accuracy of the received signal as the whole receiving device can be improved. For example, in the beamforming performed in the reception signal processing unit 107, accurate reception beamforming can be realized.

  In recent years, in an orthogonal frequency division multiplexing system generally used in mobile communication, a subcarrier located at a center frequency of a signal is not used. In the present embodiment, the correction signal is added to the frequency position of the center subcarrier of the modulation wave that is not generally used. By doing so, the received signal can be corrected without significantly affecting the modulation accuracy, and the gain and phase can be calibrated even during operation of the device. Therefore, in the present embodiment, a highly accurate received signal can be obtained even when the gain or transfer of each receiving circuit 110 changes due to a temperature change or an aging change.

  In the present embodiment, the only circuits required in the analog circuit for mounting are the correction signal local oscillator 102 and the portion that distributes the local oscillator 102 and adds it to the received signal in each receiving circuit 110. The functions required in the digital circuit are the LPF 105 and the correction parameter calculator 106. In each receiving circuit 110, the time change of the gain and the phase is considered to be relatively gradual, and therefore, the correction parameter calculator 106 is not required to have the ability to calculate at high speed. As described above, the wireless communication device according to the present embodiment can be realized with a relatively small circuit base, and can correct a received signal at low cost.

  In comparison with Patent Document 1, in Patent Document 1, since a pilot signal outside the signal band is added to the received signal, a narrow band filter is used except for a filter immediately after the antenna corresponding to the BPF 111 in the receiving circuit 110. Can not do. On the other hand, in the present embodiment, since the correction signal in the signal band is used, a narrow band filter can be used in a portion from addition to extraction of the correction signal. Therefore, in the present embodiment, the influence of the out-of-band interference wave can be reduced, and the deterioration of the reception performance can be suppressed. In Patent Document 1, it is necessary to remove out-of-band interference waves only with a filter corresponding to the BPF 111, and such a filter is basically expensive and large in size. The present embodiment also has an advantage that it is not necessary to use such an expensive and large-sized filter.

  Next, a second embodiment will be described. FIG. 6 illustrates a wireless communication device according to the second embodiment of the present disclosure. The wireless communication device 100a according to the present embodiment includes antennas 101-1 to 101-N, reception circuits 110-1 to 110-N, transmission circuits 130-1 to 130-N, and transmission / reception switches 125-1 to 125-N. N. In the present embodiment, the wireless communication device 100a is configured as a device (TDD device) that alternately switches between transmission and reception by a TDD (Time Division Duplex) method.

  In FIG. 6, some of the components of the receiving circuit 110 shown in FIG. 2 are not shown. Specifically, in FIG. 6, the illustration of the multiplier 117, the LPF 118, the corrector 120, the correction signal removing unit 121, and the like is omitted. 6 does not show the local oscillator 103 for the IF signal, the local oscillator 104 for the BB signal, the LPF 105, the correction parameter calculator 106, the received signal processing unit 107, and the like shown in FIG.

  The transmission circuit 130-n has a DAC (Digital to Analog Converter) 131-n, a multiplier 132-n, a BPF 133-n, and a high output amplifier 134-n, where n is an integer of 1 or more and N or less. Each transmission circuit 130 converts an IF signal output from a modulation device (not shown) or the like into a radio signal (transmission signal), and transmits the radio signal from antenna 101. The configuration of each transmission circuit 130 may be similar to the configuration of a normal IF conversion type transmission circuit.

  The transmission / reception switch 125 switches the connection destination of the antenna 101 between the reception circuit 110 and the transmission circuit 130. The transmission / reception switch 125 connects the antenna 101 and the reception circuit 110 during reception. In this case, the radio signal received by the antenna 101 is input to the receiving circuit 110 via the BPF 111. During transmission, the transmission / reception switch 125 connects the antenna 101 to the transmission circuit 130 at the connection destination. In this case, a radio signal output from the high-output amplifier 134 of the transmission circuit 130 is supplied to the antenna 101 via the BPF 111.

  In a normal TDD device, the transmission circuit 130 does not output a signal when the transmission / reception switch 125 selects the reception circuit 110 during reception. In the present embodiment, a part of the plurality of transmission circuits 130, for example, the transmission circuit 130-1 generates a correction signal at the time of reception. The correction signal generated by the transmission circuit 130-1 is distributed to the plurality of reception circuits 110-1 to 110-N at a stage prior to the high power amplifier 134-1. During reception, the high power amplifier 134 stops the amplification operation.

  FIG. 7A shows a spectrum of a transmission signal generated by each transmission circuit 130 at the time of transmission, and FIG. 7B shows a spectrum of a correction signal generated by transmission circuit 130-1 at the time of reception. 7A and 7B, the horizontal axis represents frequency. When transmitting, each transmission circuit 130 generates an OFDM signal including a plurality of subcarriers (see FIG. 7A). In the OFDM signal, the subcarrier (center subcarrier) at the frequency position of the carrier frequency is not used for data transmission. The carrier frequency of the OFDM signal is the same as the carrier frequency of the received signal (see FIG. 3). The OFDM signal is amplified to a wireless transmission output by the high-power amplifier 134, and wirelessly transmitted from the antenna 101.

  At the time of reception, transmission circuit 130-1 generates a CW signal (correction signal) having the same frequency as the carrier frequency instead of an OFDM signal (see FIG. 7B). The CW signal of the carrier frequency generated by the transmission circuit 130-1 at the time of reception is distributed to each reception circuit 110 and input to the adder 112 of each reception circuit 110. The correction of the gain difference and the phase difference between the plurality of receiving circuits 110-1 to 110-N using the correction signal may be the same as that described in the first embodiment.

  In the present embodiment, the wireless communication device 100a is configured as a TDD device. In general, a TDD device has a transmission signal band equal to a reception signal band. In the present embodiment, the CW signal of the carrier frequency generated by the transmission circuit 130-1 at the time of reception is used as a correction signal. In the present embodiment, since the correction signal is generated by the transmission circuit 130-1, the wireless communication device 100a does not need to have a local oscillator for the correction signal. As described above, in the present embodiment, the calibration of the receiving circuit can be performed without using the dedicated oscillator for generating the correction signal.

  In each of the above embodiments, an example has been described in which a signal having the same frequency as the carrier frequency of the received signal is used as the correction signal, but the present invention is not limited to this. For example, when a plurality of subcarriers include subcarriers not used for data transmission at a frequency position different from the frequency position of the carrier frequency, a signal having a frequency component corresponding to the unused subcarrier is used as a correction signal. You may. In this case, if the frequency position of the unused subcarrier changes over time, the oscillation frequency of the correction signal local oscillator 102 (see FIG. 2) is changed according to the change of the frequency of the unused subcarrier. Is also good.

  For example, when a correction signal having a frequency different from the carrier frequency of the received signal is used, instead of the LPF 105 (see FIG. 2), the frequency of the subcarrier to which the correction signal is added is used to extract the correction signal. BPF that allows the components to pass through may be used. Alternatively, another multiplier may be arranged in the middle of the path from the multiplier 117 to the LPF 105, and the frequency of the baseband signal may be shifted using the multiplier so that the frequency position of the correction signal becomes zero. Good.

  The wireless communication device 100 illustrated in FIG. 2 and the wireless communication device 100a illustrated in FIG. 6 are configured as, for example, DUs (Distributed Units) and may be connected to a CU (Central Unit) that performs baseband signal processing. Good. Generally, a CU is installed indoors and connected to a DU via a communication line such as an optical cable. The wireless communication device 100 configured as a DU may acquire information on a subcarrier position that is not used from a CU, for example, and generate a signal for correcting the frequency of the subcarrier position.

  Furthermore, the wireless communication device 100 may generate a correction signal of a plurality of frequencies and correct the gain and phase frequency characteristics of each receiving circuit using the plurality of subcarrier positions. For example, when there are a plurality of subcarriers not used for data transmission, wireless communication apparatus 100 simultaneously adds a correction signal to each of the frequency positions of the plurality of subcarriers, and calculates a gain difference and a phase difference at each frequency position. May be. Alternatively, the wireless communication apparatus 100 may calculate the gain difference and the phase difference a plurality of times while changing the subcarrier to which the correction signal is added, and calculate the gain difference and the phase difference at a plurality of frequency positions. Good.

  The correction parameter calculator 106 calculates a gain difference and a phase difference between the plurality of receiving circuits 110 at a plurality of frequency positions. The correction parameter calculator 106 may estimate the frequency characteristics of the gain difference and the phase difference over the entire signal band from the gain difference and the phase difference at a plurality of frequency positions using linear interpolation or the like. The corrector 120 corrects the amplitude and phase of the baseband signal using the inverse characteristic of the estimated frequency characteristic. By doing so, the frequency characteristics of the gain difference and the phase difference can be corrected. The specific processing in the corrector 120 is the same as the case where a FIR (Finite Impulse Response) filter is applied. The frequency characteristic can be corrected by obtaining an impulse response from the inverse characteristic of the estimated frequency characteristic and performing a convolution operation using the obtained impulse response as a tap coefficient.

  In each of the above embodiments, an example has been described in which the adder 112 is disposed between the BPF 111 and the LNA 113 and the correction signal is added immediately before the LNA 113. However, the present disclosure is not limited to this. The correction signal only needs to be added at an appropriate position according to the range in which the gain difference and the phase difference are calibrated. For example, when the calibration of the LNA 113 is not necessary, the adder 112 is disposed between the LNA 113 and the multiplier 114, and the correction signal is added to the received signal at a position immediately before the conversion into the IF signal. Good.

  In each of the above embodiments, an example has been described in which the receiving circuit 110 is configured as an IF conversion type receiving circuit, but the present disclosure is not limited to this. The receiving circuit 110 may be configured as a ZeroIF system or a direct RF system receiving circuit. When the receiving circuit 110 is configured as a ZeroIF receiving circuit, the received signal is not converted into an IF signal but is converted into a baseband signal as an analog signal, and then converted into a digital signal by an ADC. . When the receiving circuit 110 is configured as a receiving circuit of the direct RF system, the RF signal is converted into a digital signal by the ADC without being down-converted and as a received signal in the RF band.

  Comparing the IF conversion method and the ZeroIF method, DC leakage may occur in the ZeroIF method. When the DC leak occurs, the correction signal may not be accurately extracted from the baseband signal obtained by adding the correction signal to the frequency position of the center subcarrier. Therefore, it can be said that the IF conversion method is suitable from the viewpoint of accurately extracting the correction signal. Also in the direct RF system, since no DC leakage occurs, it is considered that the correction signal can be accurately extracted as in the case of the IF conversion system.

  In each of the above embodiments, an example has been described in which a wireless signal is modulated by a modulation method in which a specific subcarrier is not used for data transmission, but the present disclosure is not limited to this. The correction signal does not necessarily need to be added to the frequency position of a subcarrier not used for data transmission, but may be added to the frequency position of a subcarrier used for data transmission. Stated another way, the frequency of the correction signal may be the same as the frequency of the subcarrier used for data transmission. However, when a correction signal is added to a subcarrier used for data transmission, deterioration of modulation accuracy is likely to occur. In order to prevent the modulation accuracy from deteriorating, the correction signal removing section 121 may accurately remove the correction signal. Alternatively, the addition of the correction signal is performed during a time period when the signal-to-noise ratio is high enough to allow the deterioration of the modulation accuracy, or the signal power of the correction signal is set to be low, and appropriate operation is performed. The effect on reception performance degradation may be reduced.

  As described above, the embodiments of the present disclosure have been described in detail. However, the present disclosure is not limited to the above-described embodiments, and changes and modifications may be made to the above-described embodiments without departing from the spirit of the present disclosure. Are included in the present disclosure.

  For example, some or all of the embodiments described above can be described as in the following supplementary notes, but are not limited thereto.

[Appendix 1]
A plurality of receiving circuits, each receiving a radio signal through a corresponding antenna,
Compensation means for calculating at least one of the gain and the phase shift between the plurality of receiving circuits, and a correction parameter calculating means for generating a correction parameter of the received signal in each receiving circuit based on the calculated shift,
The plurality of receiving circuits, respectively,
Correction signal addition means for adding a correction signal of a predetermined frequency within the frequency band of the reception signal to the reception signal,
Correction signal extraction means for extracting the correction signal from the received signal to which the correction signal has been added and outputting the signal to the correction parameter calculation means,
Correction means for correcting at least one of the amplitude and phase of the received signal according to the correction parameter calculated by the correction parameter calculation means,
The wireless communication device, wherein the correction parameter calculation means calculates at least one of a gain and a phase shift between the plurality of reception circuits based on the correction signals input from the reception circuits through the correction signal extraction means.

[Appendix 2]
The received signal includes a plurality of subcarriers,
The wireless communication device according to claim 1, wherein the correction signal is a signal having a frequency equal to a frequency of a subcarrier not used for data transmission.

[Appendix 3]
Of the plurality of subcarriers, subsubcarriers corresponding to the frequency position of the carrier frequency of the received signal are not used for data transmission,
3. The wireless communication device according to claim 2, wherein the correction signal is a signal having a frequency equal to the carrier frequency.

[Appendix 4]
The wireless communication device according to any one of supplementary notes 1 to 3, wherein the received signal is a signal modulated by an orthogonal frequency division multiplexing method.

[Appendix 5]
A plurality of signals having different frequencies are used as the correction signal,
The correction parameter calculating means calculates at least one of a gain and a phase shift between the plurality of receiving circuits at a plurality of frequency positions, and calculates a frequency characteristic of at least one of the gain and phase shifts. The wireless communication device according to any one of the above.

[Appendix 6]
6. The wireless communication apparatus according to claim 5, wherein the correction unit corrects at least one of the amplitude and the phase of the received signal using a reverse characteristic of a frequency characteristic of at least one of the gain and the phase.

[Appendix 7]
7. The wireless communication device according to any one of supplementary notes 1 to 6, further comprising a correction signal local oscillator that generates the correction signal.

[Appendix 8]
Each of which generates a transmission signal having the same frequency as the carrier frequency of the reception signal, a plurality of transmission circuits as many as the number of the reception circuits,
Each has a connection destination of the antenna, the receiving circuit, further comprising a plurality of transmission and reception changeover switch to switch between the transmission circuit,
The transmission of the wireless signal and the reception of the wireless signal are performed by switching alternately,
The plurality of transmission / reception changeover switches, respectively, connects the antenna and the transmission circuit when transmitting the radio signal, and connects the antenna and the reception circuit when receiving the radio signal,
The wireless communication device according to any one of supplementary notes 1 to 6, wherein at least one of the plurality of transmission circuits generates the correction signal when receiving the wireless signal and outputs the signal to the plurality of reception circuits.

[Appendix 9]
The wireless communication device according to any one of supplementary notes 1 to 8, wherein each of the plurality of receiving circuits further includes a baseband signal conversion unit configured to convert a received signal to which the correction signal is added into a baseband signal.

[Appendix 10]
The plurality of receiving circuits each further include an intermediate frequency signal converting unit that converts the received signal to which the correction signal has been added into an intermediate frequency signal,
The wireless communication device according to claim 9, wherein the baseband signal conversion unit converts the intermediate frequency signal into the baseband signal.

[Appendix 11]
The wireless communication device according to supplementary note 9 or 10, wherein the correction signal extracting unit extracts the correction signal from the baseband signal.

[Supplementary Note 12]
The correction parameter calculation means sets one of the correction signals extracted by the correction signal extraction means of the plurality of reception circuits as a reference correction signal, and the correction signal extraction means of each reception circuit extracts the correction signal. The radio according to any one of supplementary notes 1 to 11, wherein a ratio between the corrected correction signal and the reference correction signal is calculated to calculate at least one of a gain and a phase shift between the plurality of receiving circuits. Communication device.

[Appendix 13]
13. The wireless communication apparatus according to claim 1, further comprising a correction signal removing unit configured to remove a component of the correction signal from a received signal in which at least one of an amplitude and a phase is corrected by the correction unit.

[Appendix 14]
An analog filter for band-limiting the received signal to which the correction signal has been added,
An analog-to-digital converter that converts the band-limited received signal to a digital signal,
14. The wireless communication device according to any one of supplementary notes 1 to 13, wherein the correction signal extracting unit extracts the correction signal from a received signal converted into a digital signal.

[Appendix 15]
Receive multiple radio signals through multiple antennas,
To each of the plurality of received signals received, add a correction signal of a predetermined frequency in the frequency band of the received signal,
Extracting the correction signal from each of the plurality of received signals to which the correction signal has been added,
Based on the correction signals extracted from the plurality of reception signals, at least one of a gain and a phase shift between the plurality of receiving circuits that receive the plurality of wireless signals is calculated, and based on the calculated shifts, Generating a correction parameter of the received signal in the receiving circuit,
A received signal correction method for correcting at least one of an amplitude and a phase of the received signal according to the calculated correction parameter.

10: Wireless communication device 20: Receiving circuit 21: Correction signal adding unit 22: Correction signal extraction unit 23: Correction unit 30: Correction parameter calculation unit 40: Antenna 100: Wireless communication device 101: Antenna 102: Localization for correction signal Oscillator 103: IF signal local oscillator 104: BB signal local oscillator 105, 118: LPF
106: correction parameter calculator 107: reception signal processing unit 110: reception circuits 111 and 115: BPF
112: Adder 113: LNA
114, 117: multiplier 116: ADC
120: Corrector 121: Correction signal remover 125: Transmission / reception switch 130: Transmission circuit 131: DAC
132: Multiplier 133: BPF
134: High power amplifier

Claims (10)

A plurality of receiving circuits, each receiving a radio signal through a corresponding antenna,
Compensation means for calculating at least one of the gain and the phase shift between the plurality of receiving circuits, and a correction parameter calculating means for generating a correction parameter of the received signal in each receiving circuit based on the calculated shift,
The plurality of receiving circuits, respectively,
Correction signal addition means for adding a correction signal of a predetermined frequency within the frequency band of the reception signal to the reception signal,
Correction signal extraction means for extracting the correction signal from the reception signal to which the correction signal has been added and outputting the signal to the correction parameter calculation means,
Correction means for correcting at least one of the amplitude and phase of the received signal according to the correction parameter calculated by the correction parameter calculation means,
The wireless communication device, wherein the correction parameter calculation means calculates at least one of a gain and a phase shift between the plurality of reception circuits based on the correction signals input from the reception circuits through the correction signal extraction means. The received signal includes a plurality of subcarriers,
The wireless communication device according to claim 1, wherein the correction signal is a signal having a frequency equal to a frequency of a subcarrier not used for data transmission. Of the plurality of subcarriers, subsubcarriers corresponding to the frequency position of the carrier frequency of the received signal are not used for data transmission,
The wireless communication device according to claim 2, wherein the correction signal is a signal having a frequency equal to the carrier frequency. A plurality of signals having different frequencies are used as the correction signal,
The correction parameter calculation unit calculates at least one of a gain and a phase shift between the plurality of receiving circuits at a plurality of frequency positions, and calculates a frequency characteristic of at least one of the gain and phase shifts. 3. The wireless communication device according to claim 3.   The wireless communication apparatus according to claim 4, wherein the correction unit corrects at least one of the amplitude and the phase of the received signal using an inverse characteristic of a frequency characteristic of at least one of the gain and the phase.   The wireless communication device according to claim 1, further comprising a correction signal local oscillator that generates the correction signal. Each of which generates a transmission signal having the same frequency as the carrier frequency of the reception signal, a plurality of transmission circuits as many as the number of the reception circuits,
Each has a connection destination of the antenna, the receiving circuit, further comprising a plurality of transmission and reception changeover switch to switch between the transmission circuit,
The transmission of the wireless signal and the reception of the wireless signal are performed by switching alternately,
The plurality of transmission / reception changeover switches, respectively, connects the antenna and the transmission circuit when transmitting the radio signal, and connects the antenna and the reception circuit when receiving the radio signal,
The wireless communication device according to claim 1, wherein at least one of the plurality of transmission circuits generates the correction signal when receiving the wireless signal and outputs the signal to the plurality of reception circuits.   8. The wireless communication apparatus according to claim 1, further comprising a correction signal removing unit configured to remove a component of the correction signal from a received signal in which the correction unit corrects at least one of an amplitude and a phase. 9. An analog filter for band-limiting the received signal to which the correction signal has been added,
An analog-to-digital converter that converts the band-limited received signal to a digital signal,
9. The wireless communication apparatus according to claim 1, wherein the correction signal extracting unit extracts the correction signal from a received signal converted into a digital signal. 10. Receive multiple radio signals through multiple antennas,
To each of the plurality of received signals received, add a correction signal of a predetermined frequency in the frequency band of the received signal,
Extracting the correction signal from each of the plurality of received signals to which the correction signal has been added,
Based on the correction signals extracted from the plurality of reception signals, at least one of a gain and a phase shift between the plurality of receiving circuits that receive the plurality of wireless signals is calculated, and based on the calculated shifts, Generating a correction parameter of the received signal in the receiving circuit,
A received signal correction method for correcting at least one of an amplitude and a phase of the received signal according to the calculated correction parameter.

Images