JP4447380B2 - Array antenna receiver and transmitter - Google Patents

Description

  The present invention relates to an array antenna receiving apparatus and a transmitting apparatus.

  As an advance from the third generation mobile communication, an even higher speed transmission is assumed, and an adaptive array antenna is an important technology for realizing the service. This adaptive array antenna uses a plurality of antenna elements, weights received signals appropriately, combines them, directs the main beam in the direction of arrival of the desired signal, and forms a directional zero in the direction of arrival of the interference signal The directivity can be controlled.

  In the adaptive array antenna as described above, in order to generate a transmission / reception beam with a high-precision main beam / null directed to the actual signal arrival direction of the desired wave / interference wave signal, in the uplink / downlink, It is necessary to perform calibration to compensate for the phase / amplitude deviation generated between the RF transmission circuit / reception circuit branches corresponding to the number of antennas. Here, calibration in the RF transmission circuit is called RF transmission circuit calibration, calibration in the RF reception circuit is called RF reception circuit calibration, and a general term for RF transmission circuit calibration and RF reception circuit calibration is RF radio circuit calibration. This is called

  FIG. 12 is a block diagram showing a configuration example of a conventional RF radio transmission circuit using an adaptive array antenna, and FIG. 13 is a block diagram showing a configuration example of a conventional RF radio reception circuit using an adaptive array antenna. is there. As shown in the figure, RF transmitter / receiver circuits are provided in parallel for the number of antenna branches (B). Since the RF transmission circuit / reception circuit for each antenna branch has the same configuration, an RF transmission circuit / reception circuit for antenna branch # 1 will be described as an example here.

  As shown in FIG. 12, the RF transmission circuit # 1 includes a digital / analog signal conversion processing unit 102, a quadrature modulation unit 103, a mixer (multiplier) 104, and a high-power amplifier.

  An input signal input to the digital / analog signal conversion processing unit 102 is digital-analog converted and orthogonally modulated by the orthogonal modulation unit 103. The signal subjected to quadrature modulation by the quadrature modulation unit 103 is frequency-converted (up-converted) by the mixer 104, which is a non-linear circuit, with the local frequency, amplified by the high-power amplifier 105, and then transmitted via the antenna.

  On the other hand, as shown in FIG. 13, the RF receiver circuit # 1 includes a low noise amplifier 202, a mixer (multiplier) 203, a band-limited pass filter 204, and an automatic amplification gain control unit (AGC (Automatic Gain Control)). Circuit) 205, quadrature detection unit 206, reception level measurement unit 207, and analog / digital signal conversion processing unit 208.

  An RF (Radio Frequency) received signal received via an antenna is amplified by a low noise amplifier 202, then frequency-converted (down-converted) by a local frequency and a mixer 203, passes through a band-limited pass filter 204, and is AGCed. Input to the circuit 205. The AGC circuit 205 automatically controls fluctuations in the reception level measured after quadrature detection. The received signal output from the AGC circuit 205 is analog-to-digital converted by the analog / digital signal conversion processing unit and output to the subsequent stage as an output signal.

When a radio frequency (RF) signal passes through the RF transmitter / receiver circuit as described above, the amplitude / phase deviation between the antenna branches is affected by individual elements of amplifiers, mixers, and other active elements and parts constituting the circuit. Will appear as. In particular, the influence of individual differences between the AGC circuit in the RF receiving circuit and the high-power amplifier in the RF transmitting circuit becomes prominent. These influences cause degradation of adaptive array antenna characteristics, causing a problem that directivity different from expected directivity is formed. Therefore, in order to prevent the influence, it is necessary to perform calibration so that the characteristics of the RF transmission circuit / reception circuit are the same.
In addition, the amplitude / phase deviation between the antenna branches fluctuates due to aging and temperature changes. Therefore, in consideration of operation in an actual system, in order to always generate a high-accuracy beam using an array antenna, an actual uplink / downlink received / transmitted signal is received / transmitted, It is essential to calibrate the RF radio circuit constantly or periodically.

  From this point of view, a technique relating to an array antenna apparatus capable of appropriately and accurately performing a calibration operation corresponding to a characteristic change caused by a temperature change or the like is disclosed (for example, see Patent Document 1).

  Further, as a technique for calibrating an RF receiver circuit using a reference signal, a method has been proposed in which a downlink actual transmission signal converted into an uplink carrier frequency is used as a reference signal (for example, non-conversion). Patent Document 1).

Patent Document 2 discloses a technique for calibrating a directional antenna device using a reference signal. According to this document, by comparing the generated reference signal with the received signal, the phase amplitude error of the received output signal of the receiving system corresponding to the reference signal and each antenna element is detected, and the calibration value for calibration In the baseband. Thus, it is described that the phase difference and amplitude difference of each element can be accurately corrected.
JP 2003-234610 A JP 2002-141730 A Koji Fukino, Yoshihiko Takeuchi, “Automatic calibration method using LMS algorithm for array antenna radio section in DS-CDMA”, IEICE Technical Report RCS2000-31, June 2000

  As described above, in the method of calibrating the RF receiver circuit using the downlink actual transmission signal converted to the uplink carrier frequency as a reference signal, the uplink and downlink bandwidths / radio access When the system is the same (for example, W-CDMA for third generation mobile communication), for example, the uplink as studied in the fourth generation mobile communication is MC / DS-CDMA (example), When the downlink is different in radio access method and bandwidth as in OFCDM (example), the downlink transmission signal cannot be used as a reference signal for calibration due to a difference in characteristics such as a filter due to the difference between the two. That is, in the conventional method, sufficient consideration has not been given to the generation of the reference signal when the uplink and downlink radio access methods and bandwidths are different.

  In the system operation state, the amplification gain of the AGC circuit may vary depending on the reception level, and the transmission output of the high-power amplifier may vary depending on the transmission power control, etc. It fluctuates under the influence of this fluctuation.

  Further, the amplitude / phase deviation between the branches of the RF radio circuit also varies depending on the temperature change / aging change as described above.

  Therefore, when performing calibration of the RF radio circuit in an actual system operation state, it is possible to achieve highly accurate calibration unless all the fluctuation factors of the amplitude / phase deviation between the branches of the RF radio circuit are taken into consideration. difficult.

  The present invention has been made in view of the above problems, and a first problem is to calibrate an RF radio circuit with high accuracy without depending on uplink and downlink radio access methods and bandwidths. It is an object of the present invention to provide an array antenna receiving apparatus and a transmitting apparatus that can be used.

  Another object of the present invention is to provide an array antenna receiving apparatus and transmitting apparatus that can perform calibration of an RF radio circuit in a system operation state with high accuracy.

In order to solve the first problem , according to an aspect of the present invention , in an array antenna receiving apparatus including an array antenna including a plurality of antenna elements, calibration is performed using a spread signal or a non-spread signal. A reference signal generating means for generating a reference signal of the signal, and correcting an amplitude deviation and a phase deviation generated between branches of the receiving circuit provided corresponding to each of the plurality of antenna elements by using the generated reference signal and reception calibration value calculating means for calculating a calibration value required to a correction means for correcting an amplitude deviation and phase deviation generated between the branches of the receiver circuit using the calculated calibration values , it is Bei Ete a.

Also, according to an aspect of the present invention, in the array antenna receiving apparatus, when generating the reference signal using a spread signal, the reference signal generating means performs spread modulation using a spread code orthogonal to the communication channel The reference signal is generated using a chip pattern obtained by applying a chip repetition of a predetermined number of repetitions to a spread signal or a spread chip sequence orthogonal to a communication channel.

Also, according to an aspect of the present invention, in the array antenna receiving apparatus, when the reference signal generating unit generates a reference signal using a spread signal, a spread code that is non-orthogonal to the communication channel is used. The reference signal is generated for each subcarrier or with the bandwidth of all subcarriers.

Also, according to an aspect of the present invention, in the array antenna receiving apparatus, when the reference signal generating unit generates a reference signal using a non-spread signal, the center frequency for each subcarrier or all subcarriers The reference signal is generated at each center frequency.

In order to solve the second problem , according to an aspect of the present invention , in the array antenna reception apparatus, the reception signal is a multicarrier signal, and the reception calibration value calculation means is provided for each subcarrier. And a table storage means for calculating a calibration value of the reception circuit between the branches for each amplification gain of the automatic amplification gain control section provided in the reception circuit, and storing the result in a memory as a table, the correction means are are each amplification gain stored in the table, each subcarrier, we line correction of amplitude deviation and phase deviation generated between the branches of the receiver circuit using a different calibration values for each branch.

Further, according to an aspect of the present invention, in the array antenna receiving apparatus, the reception calibration value calculation means is configured such that each time the amplification gain of the automatic amplification gain control unit varies, each amplification gain value after variation varies. A calibration value for each branch and each subcarrier is calculated, and a first reception calibration value updating unit for updating the contents of the table based on the calculation result is provided, and the correction unit includes the updated table. It is characterized in that the amplitude deviation and the phase deviation occurring between the branches of the receiving circuit are corrected by using different calibration values for each stored amplification gain, each subcarrier, and each branch.

Further, according to an aspect of the present invention, in the array antenna receiving apparatus, the reception calibration value calculating means each time the amplification gain of the automatic amplification gain control unit fluctuates, A second reception calibration value updating unit configured to calculate a calibration value at each amplification gain value for each carrier and update the contents of the table based on the calculation result; and the correction unit includes the updated table The amplitude deviation and the phase deviation generated between the branches of the receiving circuit are corrected by using different calibration values for each amplification gain, subcarrier, and branch stored in the receiver.

In order to solve the above second problem, the array antenna transmitting apparatus according to an embodiment of the present invention, the array antenna transmitting apparatus comprising an array antenna composed of multiple antenna elements, the transmitted signal is a multicarrier signal An amplitude deviation and a phase deviation generated between branches of the transmission circuit for each subcarrier, for each transmission output of an amplifier provided in the transmission circuit provided corresponding to each of the plurality of antenna elements. Transmission calibration value calculation means for calculating a calibration value necessary for correcting the image , table storage means for storing the calculated calibration value in a memory as a table, and calibration values stored in the table Correction means for correcting amplitude deviation and phase deviation generated between the branches of the transmission circuit, It is characterized in that it comprises.

Also, according to an aspect of the present invention, in the array antenna transmission apparatus, the transmission calibration value calculation means includes each branch and each sub-band in the transmission output value after the fluctuation every time the transmission output of the amplifier fluctuates. First calibration value updating means for calculating a calibration value for each carrier and updating the contents of the table based on the calculation result is provided, and the correction means is a transmission stored in the updated table. It is characterized in that the amplitude deviation and the phase deviation generated between the branches of the transmission circuit are corrected using different calibration values for each output, each subcarrier, and each branch.

Also, according to an aspect of the present invention, in the array antenna transmission device, the transmission calibration value calculation means each time the transmission output of the amplifier fluctuates, for each branch, for each subcarrier, for each A second transmission calibration value updating unit configured to calculate a calibration value in the transmission output value and update the contents of the table based on the calculation result; and the correction unit is stored in the updated table. It is characterized in that the amplitude deviation and the phase deviation generated between the branches of the transmission circuit are corrected using different calibration values for each transmission output, each subcarrier, and each branch.

  According to the present invention, a calibration-dedicated signal is generated in the array antenna receiver using a spread signal or a non-spread signal, so that calibration is performed accurately even if there is a difference in the radio access method or bandwidth. be able to.

  Also, whenever the amplification output of the automatic amplification gain control unit (AGC circuit) / transmission output of the amplification unit fluctuates, the RF transmission / reception unit is calibrated, and the calibration value at the amplified gain / transmission output after fluctuation is calculated. By updating, it is possible to calibrate the RF transmission / reception unit with high accuracy even during reception / transmission of uplink / downlink signals.

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

(First embodiment)
FIG. 1 is a block diagram showing a configuration example of an array antenna receiving apparatus 1 according to an embodiment of the present invention.

  FIG. 1 shows a configuration of an array antenna (example: adaptive array antenna) receiving apparatus using B (# 1 to #B) antenna elements as an example. Further, in the array antenna receiving apparatus 1 in the present embodiment, a multicarrier transmission scheme, for example, an MC / DS-CDMA transmission scheme, is applied to uplink signal reception, and the description will proceed below. The MC / DS-CDMA transmission scheme is a scheme for transmitting a DS-CDMA signal in parallel using a plurality of subcarriers, and is essentially the same as DS-CDMA spreading in the time domain.

  In the figure, this array antenna receiving apparatus 1 includes B antenna elements 11-1 to 11-B, duplexers 12-1 to 12-B provided corresponding to the antenna elements, and an RF receiving unit 13-. 1 to 13-B, a measurement branch changeover switch A14, calibration value multiplication units 15-1 to 15-B, a measurement branch changeover switch B16, a gain adjustment unit 17, a calibration RF transmission unit 18, The calibration value measuring unit 19 and a calibration reference signal generator 20 are included. In the figure, the RF transmitters 31-1 to 31-B are indicated by dotted lines, but the description thereof is omitted because they are not directly related to the present embodiment.

  The calibration reference signal (baseband signal) generated by the calibration reference signal generator 20 is input to the calibration value measurement unit 19 and the calibration RF transmission unit 18, respectively. A method for generating the calibration reference signal will be described later.

  The calibration reference signal is converted into orthogonal subcarriers by inverse fast Fourier transform (not shown), and then input to the calibration RF transmission unit 18 where filtering, frequency conversion to the RF band, and the like are performed. Are processed and converted into an RF transmission signal. After that, gain adjustment is performed by the gain adjustment unit 17, and the transmission output from each branch is distributed by the duplexers 12-1 to 12-B and input to the RF reception units 13-1 to 13-B. Thereafter, despreading and fast Fourier transform (not shown) are performed to obtain a reception baseband signal for each subcarrier, and the output is switched for each measurement branch by the measurement branch switch A14 and input to the calibration value measurement unit 19. .

  The calibration value measuring unit 19 uses the reference signal generated by the calibration reference signal generator 20 for the calibration value for each subcarrier, each branch, and transmission output after passing through the RF receiving unit of each branch. (Calculate) and output the result to the calibration value multipliers 15-1 to 15-B.

  The calibration value output from the calibration value measuring unit 19 is multiplied by the transmission baseband signal of each subcarrier after the fast Fourier transform in the calibration value multiplying units 15-1 to 15-B. As a result, the amplitude / phase deviation of the received signal of each subcarrier is corrected.

  Next, a method for generating a calibration reference signal generated by the calibration reference signal generator 20 will be described with reference to FIG. FIG. 2 is a diagram showing the spectrum of the calibration reference signal. The calibration reference signal generation method according to the present embodiment uses a spread signal (wideband signal) to generate a calibration reference signal and does not use a spread signal (non-spread signal (narrowband signal)). Are roughly divided into two cases in which a calibration reference signal is generated. For example, when a multi-carrier transmission scheme, for example, MC / DS-CDMA, MC-CDMA, or the like is used for an uplink radio access scheme, a reference signal for calibration is generated using a spread signal, and OFDM is used. If so, the reference signal for calibration is generated without using the spread signal. Hereinafter, specific examples will be described.

1. When a calibration reference signal is generated using a spread signal (calibration reference signal generation method 1)
Calibration reference signal generation method 1 is a calibration reference signal spread with a spread signal (or orthogonal or non-orthogonal to the communication channel) equivalent to the bandwidth of the uplink subcarrier (equivalent to the chip rate). Is generated for each subcarrier (see FIG. 5A).

  According to this generation method, the calibration reference signal is generated so that the transfer characteristic (amplitude / phase deviation) when an actual communication signal passes through the RF receiver is reproduced. Then, the calibration value measuring unit 19 compares the generated calibration reference signal with the received baseband signal for each subcarrier after passing through the RF receiving units 13-1 to 13-B. Can be measured with high accuracy.

(Calibration reference signal generation method 2)
The calibration reference signal generation method 2 is generated when the uplink variable spreading factor / chip repetition factor (VSCRF) -CDMA scheme, which is studied in the fourth generation mobile communication, is used as the uplink radio access scheme. A calibration reference signal is generated using a chip repetition pattern orthogonal to the communication channel and spread orthogonal to the communication channel (see FIG. 5B).

  According to this generation method, it is possible to generate a calibration reference signal that uses a chip repetition pattern orthogonal to the communication channel of each user.

(Calibration reference signal generation method 3)
The calibration reference signal generation method 3 generates a calibration reference signal spread with a spreading code equivalent to the entire bandwidth of all subcarriers (non-orthogonal to the communication channel) (see FIG. 8C). ).

  According to this generation method, a value averaged over the entire frequency band is generated as a reference signal for calibration. In addition, when the frequency variation for each subcarrier is small, in this generation method, no signal is generated for each subcarrier, and therefore the configuration of the calibration reference signal 20 can be simplified.

2. When generating a calibration reference signal without using a spread signal (calibration reference signal generation method 4)
The calibration reference signal generation method 4 generates a non-spread (narrowband) calibration reference signal for each center frequency of each subcarrier (see FIG. 4D).

  According to this generation method, it is not necessary to diffuse the calibration reference signal, so that the configuration of the calibration reference signal generation unit 20 can be simplified.

(Calibration reference signal generation method 5)
The calibration reference signal generation method 5 generates a narrowband calibration signal at the center frequency of all subcarriers (see FIG. 5E).

According to this generation method, it is not necessary to diffuse the calibration signal, and further, it is not necessary to generate a calibration reference signal for each subcarrier. Therefore, the configuration of the calibration reference signal generation unit 20 is greatly increased. Can be simplified.
(Calibration Reference Signal Generation Method 6)
The calibration reference signal generation method 6 generates a large number of narrowband signals uniformly over the bandwidth of all subcarriers (see FIG. 8F).

  According to this generation method, the amplitude / phase deviation for each frequency can be obtained, and calibration can be executed with high accuracy.

  As described above, according to the present embodiment, it is possible to properly use the calibration reference signal generated based on the spread signal and the calibration reference signal generated based on the non-spread signal according to the uplink radio access scheme. As a result, it is possible to realize calibration in a flexible array antenna receiving apparatus that does not depend on the access method.

  In the said embodiment, although the aspect which outputs the calibration value calculated in the calibration value measurement part 19 to the calibration value multiplication part 15-1 to 15-B was illustrated, in 2nd Embodiment shown below, Calibration values calculated by the calibration value measuring unit 19 are generated as a calibration table and stored in a memory (not shown). Hereinafter, specific examples will be described.

(Second Embodiment)
The configuration of the array antenna receiving apparatus 2 according to the present embodiment is shown in FIG.

  As shown in FIG. 3, the array antenna receiving apparatus 2 according to the present embodiment has the same basic configuration as the array antenna receiving apparatus 1 shown in FIG. 1, but includes a calibration table updating unit 40, an automatic amplification gain unit, and the like. The difference is that the storage unit 41 is newly provided. Therefore, the description of the same components will be omitted below, and differences from the first embodiment will be described in detail.

  In FIG. 3, in the present embodiment, the calibration value measurement unit 19 is provided for each amplification gain of the automatic amplification gain control unit (= AGC circuit) provided in the RF reception units 13-1 to 13 -B for each subcarrier. The RF reception units 13-1 to 13 -B between the branches are output to the calibration table update unit 40. The automatic amplification gain storage unit 41 stores the amplification gain amount of the AGC circuit at the time of calibration value measurement.

  The calibration table update unit 40 generates different calibration values output from the calibration value measurement unit 19 for each automatic amplification gain, each subcarrier, and each branch as a calibration table, and stores the result in the memory. .

  FIG. 4 is a diagram illustrating a calibration table generation example generated by the calibration table update unit 40.

As shown in the figure, this calibration table is a three-dimensional array, and each dimension corresponds to the coordinates of the X axis, Y axis, and Z axis of the space. Each element is stored in a data format such as the X axis of the branch, the Y axis of the automatic amplification gain output from the automatic amplification gain storage unit 41, and the Z axis of the subcarrier (block). Here, C _{i, j, k} represents a calibration value (amplitude / phase deviation), i represents a branch, j represents an automatic amplification gain, and k represents a subcarrier (block). For example, from this calibration table, the calibration value of the spatial coordinates (1,1,1) is C _1,1,1 and is referred to as branch Br # 1, automatic amplification gain amount “1”, and subcarrier “1”. I understand that. That is, by using such a calibration table, it is possible to correct the amplitude / phase deviation of the received signal using different calibration values for each amplification gain, each subcarrier, and each branch.

  The calibration table generated as described above is first generated as an initial table when the array antenna receiving apparatus 2 is installed (before an actual uplink signal is received (also referred to as an offline state)) and stored in a memory. It is done.

  By the way, the reception level in the uplink fluctuates in time due to the influence of fading and shadowing. The automatic amplification gain of the AGC circuit varies according to the variation of the reception level. Further, the calibration value for the automatic amplification gain value of the AGC circuit varies due to temperature change / aging change. Therefore, in this embodiment, every time the automatic amplification gain value of the AGC circuit fluctuates, the RF receivers 13-1 to 13-B are calibrated, and the calibration value in the automatic amplification gain value after the fluctuation is calculated. The calibration table is updated using the calculated value. For example, the calibration table is updated according to the calibration table update method shown in FIG.

  FIG. 4A shows an example of the initial value of the calibration table. Here, in order to simplify the explanation, a calibration table arranged in two dimensions is used, the X axis is a branch, and the Y axis is an automatic amplification gain value of the AGC circuit.

When the array antenna receiving apparatus 2 starts receiving uplink signals (also referred to as an online state), and the fluctuation in the AGC amplification gain value G ₁ is detected in the calibration value measuring unit 19, the AGC after the fluctuation is detected. A calibration value in a certain branch and a certain subcarrier at the amplification gain value G ₁ is calculated, and the result is output to the calibration table updating unit 40.

The calibration table update unit 40 updates the calibration table based on the calculation result received from the calibration value measurement unit 19 (the b1 line in FIG. 5B is updated). Here, the calibration value before update is C _{i, j, k} (i: branch, j: automatic amplification gain value, k: subcarrier), and the calibration value after update is C ′ _{i, j, k} . . A specific update formula (calculation formula) of the calibration value in this embodiment will be described later.

Subsequently, when the calibration value measurement unit 19 detects that the AGC amplification gain value has changed from G _{1 to} G ₂ , each branch in the AGC amplification gain value G ₂ after the change (here, each subcarrier is omitted). The calibration value is calculated every time and the result is output to the calibration table update unit 40.

The calibration table update unit 40 updates the calibration table based on the calculation result (the c2 line in FIG. 3C is updated). Similarly, the calibration value measuring unit 19 calculates the calibration value every time the AGC amplification gain value varies G ₃ → G ₄ → G _5, and the calibration table updating unit 40 sequentially updates the calibration table. Is done.

  Next, a calibration value update formula will be described.

The following method can be considered as a method for updating the calibration value. The calibration value before update is C _{i, j, k} (i: branch, j: AGC amplification gain value, k: subcarrier), the calibration value after update is C ′ _{i, j, k} , and the AGC circuit Assuming that the calibration values measured after fluctuation of the amplification gain (assuming j = J) are Di _{, J, k} , the calibration update value is calculated according to one of the following formulas (1) to (3). The

(Formula 1)
C ′ _{i, J, k} = D _{i, J, k}
The above equation 1 is a method in which the calibration value measured after the AGC amplification gain value fluctuates is used as it is as the update value.

(Formula 2)
C ′ _{i, J, k} = A × C _{i, J, k} + (1−A) × D _{i, J, k}
Here, A represents a forgetting factor (fixed value).
Equation 2 is a method that uses a forgetting factor to calculate the calibration update value. The forgetting factor in this equation is introduced for the following reason.

  If the fluctuation of the amplification gain value of the AGC circuit is gradual, the calibration execution time can be extended, so that a relatively accurate calibration update value can be obtained. However, the reception level is high due to fading. When the variation of the amplification gain value of the AGC circuit is severe, the calibration execution time is shortened, and it is difficult to perform calibration with high accuracy. This method 2 considers such a situation, and updates the calibration value measured after the fluctuation of the amplification gain value of the AGC circuit by gradually forgetting it using the forgetting coefficient, thereby updating the AGC amplification gain value. Even in the case where the fluctuation is severe, the calibration can be performed with sufficient accuracy.

  In addition, the value of the forgetting factor can be changed according to the variation time of the amplification gain value of the AGC circuit.

(Formula 3)
If the measurement time of _{Di, j, k} is T,
(A) When T ≦ T _max (T _max : constant),
C ′ _{i, J, k} = (1−T / T _max ) A × C _{i, J, k} + T / T _max × D _{i, J, k}
(B) If T> T _max ,
C ′ _{i, J, k} = D _{i, J, k}
The above equation (3) is a method of switching the above equations (1) and (2) according to the calibration table values D _{i, J, k} measured after the variation of the amplification gain value of the AGC circuit. For example, defining a maximum measurement time of measuring the calibration value as _{T max,} the _{D i, J,} measuring time T _{k is} used _{T max} following value, if the equation (b), the measurement time T, T If it is greater than or equal to _max , the above equation (a) is used.

  As described above, according to the present embodiment, the calibration of the RF receivers 13-1 to 13-B is performed each time the amplification gain of the AGC circuit in the RF receivers 13-1 to 13-B varies. Since the calibration value is updated using the calibration measurement value at each branch and each subcarrier in the amplification gain of the AGC circuit during the calibration value measurement, the reception level fluctuation, temperature change / aging Even when the calibration value for the amplification gain value of the AGC circuit changes greatly due to the change, the RF receiver calibration for each AGC amplification gain with high accuracy during the reception of the actual uplink signal (online) Can be performed.

  In the calibration table updating method shown in FIG. 5 described above, an example in which only the calibration value for each branch and each subcarrier in the AGC amplification gain value after the change is illustrated, but the calibration table updating method in the present invention is It is not limited to such a method. Hereinafter, a modified example of the calibration table update method will be described with reference to FIG.

  The calibration table update method shown in FIG. 6 performs calibration of the RF receivers 13-1 to 13-B every time the AGC amplification gain value fluctuates, and each time, each branch, each subcarrier, each AGC amplification. Update all calibration values with gain values.

FIG. 6A shows an example of the initial value (offline state) of the calibration table. The RF receiver is calibrated before receiving the actual uplink signal, and is obtained by the calibration. Each branch, each AGC amplification gain value, and each subcarrier calibration value C _{i, j, k} are reflected in the table. Similarly to FIG. 5, the calibration table is configured in a two-dimensional array, with the X axis as a branch and the Y axis as an automatic amplification gain value.

Next, in the array antenna receiving apparatus 2 are received uplink signal is (online), the AGC amplifier gain value by the calibration value measuring unit 19 is detected to have varied in G _1, the calibration value measuring unit 19 calculates calibration values C ′ _{i, G 1, k} at the changed AGC amplification gain value G 1 during calibration, and calculates all the AGC amplification gain values according to the following calculation formula (4). Calibration values C ′ _{i, j, k} in the RF receivers 13-1 to 13-B of the first and second receivers 13-1 to 13-B are calculated, and the result is output to the calibration table update unit 40 to update the table (see FIG. 4B). ).

(Formula 4)
C ′ _{i, j, k} = C _{i, j, k} × (C ′ _{i, G1, k} / C _{i, G1, k} )
Ci _{, J, and k} represent calibration values at the AGC amplification gain G1 before calibration.

Thereafter, each time the amplification gain value of the AGC circuit changes in the same manner, calibration values C ′ _{i, j, k} at the changed AGC amplification gain value are obtained, and all the AGCs are obtained according to the above equation (4). Calibration values C ′ _{i, j, k} in the RF receivers 13-1 to 13-B at the amplification gain value are calculated, and the calibration table is updated (see FIGS. 3C and 3D).

  As described above, according to the present embodiment, the entire calibration table is uniformly updated based on the ratio between the calibration value before the update and the calibration value after the update, thereby increasing the amplification gain of the AGC circuit. Even when the value fluctuates relatively depending on the reception level or temperature change / aging change, the calibration values of the RF receivers 13-1 to 13-B are accurately calculated for each amplification gain of the AGC circuit. It is possible to obtain.

  By the way, the AGC circuits in the RF receivers 13-1 to 13-B change the amplification gain value according to the reception level as described above, and the width to be changed is generally called a step size. This step size is set to about 1 dB as shown in FIG. 7A from the viewpoint of reducing characteristic degradation due to quantization error in an A / D converter (not shown) downstream of the AGC circuit as much as possible. There are many cases.

  Since the calibration table uses AGC amplification gain for each AGC amplification gain, that is, the Y axis is a step size, if the step size is set to be as small as 1 dB, the number of AGC amplification gains proportional to the input dynamic range in the A / D converter ( The number of Y-axis on the table) is required, which is not desirable in terms of mounting the apparatus, which increases the memory capacity for storing the table. Therefore, in the present embodiment, the step size of the AGC circuit is set to be a few dB to 10 dB larger than the conventional step size. As a result, as shown in FIG. 5B, the fluctuation of the AGC amplification gain due to the fluctuation of the reception level can be reduced, and the measurement time of the calibration value at each AGC amplification gain value can be lengthened. Has an effect. As a result, calibration of the RF receivers 13-1 to 13-B can be performed with high accuracy.

  Further, the range of the vertical axis of the AGC amplification gain on the calibration table can be reduced, and an increase in the memory capacity for storing the calibration table can be prevented.

  The principle of the calibration value updating method in the array antenna receiving apparatus according to the present invention described above can also be applied to the array antenna transmitting apparatus on the transmitting side.

  FIG. 8 is a block diagram showing a configuration example of the array antenna transmission apparatus 3 according to the embodiment of the present invention.

  As shown in FIG. 8, the array antenna transmission apparatus 3 in the present embodiment is provided corresponding to the B antenna elements 11-1 to 11 -B and the antenna elements 11-1 to 11 -B. Duplexers 12-1 to 12-B, RF transmission units (transmission circuits) 31-1 to 31-B, inverse fast Fourier transform units (IFFT (Inverse Fast Fourier Transform)) 51-1 to 51-B, measurement A branch changeover switch A52, calibration value multiplying units 53-1 to 53-B, a measurement branch changeover switch B54, a calibration RF receiving unit 55, a fast Fourier transform unit (FFT (Fast Fourier Transform)) 56, , A calibration value measuring unit 57, a calibration table updating unit 58, and a high output amplifier output level storage unit 59. In the array antenna transmission apparatus 3 according to the present embodiment, a multi-carrier transmission scheme, for example, an MC-CDMA transmission scheme or VSF-OFCDM (Variable Spreading Factor Orthogonal Frequency and Frequency) with a variable CDMA spreading factor is used for downlink signal transmission. It is assumed that a Code Division Multiplexing) transmission method is applied, and the description will be given below.

  In the array antenna transmission apparatus 3 according to the present embodiment, the same symbol is copied by the amount corresponding to the subcarrier, and each is multiplied by a spreading code, and then subjected to inverse Fourier transform in the inverse fast Fourier transform units 51-1 to 51-B and orthogonal. It is converted into a multicarrier signal (transmission signal).

  The transmission signals input to the RF transmitters 31-1 to 31 -B are subjected to processing such as filtering and frequency conversion to the RF band, and the respective antennas (# 1 to # 1) are passed through the duplexers 12-1 to 12 -B. #B) is supplied to 11-1 to 11-B.

  RF band transmission signals (hereinafter referred to as RF transmission signals) branched by the duplexers 12-1 to 12-B are switched for each measurement branch by the measurement branch switching switch B54, and the RF transmission signal for each branch is calibrated. The signal is input to the RF reception unit 55 for communication.

  The calibration RF receiving unit 55 performs processing such as filtering and frequency conversion to the baseband on the received RF transmission signal, and outputs the result to the fast Fourier transform unit 56. Then, the fast Fourier transform unit 56 performs a fast Fourier transform process on the input signal, thereby obtaining a reception signal for each subcarrier. The reception signal for each subcarrier obtained in this way is input to the calibration value measurement unit 57.

  The calibration value measurement unit 57 has a function of calculating a calibration value for each subcarrier. In the array antenna transmission apparatus 3 in the present embodiment, an actual downlink transmission signal is used as a reference signal. Specifically, the calibration value measuring unit 57 performs each subcarrier after the Fourier transform on each subcarrier before the inverse Fourier transform and the transmission baseband signal of each branch that are switched and output by the measurement branch switch A52. A calibration value is calculated for each output level (transmission output level) of the high output amplifier (not shown) in each branch / RF transmission unit 31-1 to 31 -B, and the result is sent to the calibration table update unit 58. Output. The high output amplifier output level storage unit 59 stores a calibration value at the time of calibration value measurement.

  The calibration table update unit 58 generates different calibration values for each transmission output, each subcarrier, and each branch output from the calibration value measurement unit 57, and stores the result in the memory.

  FIG. 9 is a diagram illustrating a generation example of the calibration table generated by the calibration table update unit 58. This calibration table is basically the same as the calibration table in the array antenna receiving apparatus shown in FIG. 4 described above, except that the Y axis represents the output level after amplification by the high-power amplifier. That is, for each subcarrier, the calibration values in the RF transmission units 31-1 to 31-B between the branches for each transmission output level after high output amplification (or before amplification) are reflected in the same table. In other words, by referring to such a calibration table, the amplitude / phase deviation of the transmission signal is corrected using different calibration values for each output level, each subcarrier, and each branch after high output amplification. Is possible.

  The calibration table generated as described above is first generated as an initial table and stored in a memory when the array antenna transmission apparatus 3 is installed (before an actual downlink signal is transmitted (offline state)).

  By the way, the transmission output level in the downlink varies with time due to transmission power control. Further, the calibration value with respect to the transmission output level of the high-power amplifier varies due to temperature change / aging change. Therefore, in this embodiment, every time the transmission output level of the high-power amplifier varies, the RF transmitters 31-1 to 31-B are calibrated, and the calibration value at the transmission output level after the variation is calculated. The calibration table is updated using the calculated value. For example, the calibration table is updated according to the calibration table update method shown in FIG. The basic principle of the calibration table update method in the present embodiment is the same as the calibration table update method of the RF receivers 13-1 to 13 -B shown in FIG. 5 described above. Whereas the calibration table update method of the RF receivers 13-1 to 13-B shown in FIG. 5 calculates the calibration value for the amplified gain value after the change, the calibration of the RF transmitters 31-1 to 31-B is performed. In the transmission table update method, the RF transmitters 31-1 to 31-B are calibrated every time the transmission output level changes, and the calibration values for each branch and each subcarrier with respect to the changed transmission output are updated. .

  That is, according to the present embodiment, the RF transmitters 31-1 to 31-B are calibrated each time the transmission output level of the high-power amplifier in the RF transmitters 31-1 to 31-B varies. The calibration value is updated using the calibration measurement value at each branch and each subcarrier at the transmission output level of the high-power amplifier during the calibration value measurement. Even when the calibration value for the transmission output level of the high-power amplifier changes greatly due to secular change, RF transmission for each transmission output level with high accuracy during actual downlink signal transmission (online) Part calibration can be performed. Note that any one of the above formulas (1) to (3) may be used as the calibration update formula.

  FIG. 11 shows a modification of the calibration table update method described above, and the basic principle is the same as that of the calibration table update method of the RF receiver shown in FIG. 6 described above. In the case of this method, the RF transmitters 31-1 to 31 -B are calibrated each time the transmission output level fluctuates, and each time, the calibration value at each transmission level for each branch and each subcarrier. Update all of. That is, according to the present embodiment, the entire calibration table is uniformly updated based on the ratio between the calibration value before the update and the calibration value after the update, thereby transmitting the output on the calibration table. Even when the level varies relatively due to transmission power control or temperature / aging changes, it is possible to obtain the calibration value of the RF transmission unit for each transmission output level with high accuracy.

  In the above embodiment, the function of the calibration reference signal generator 20 in the array antenna receiving apparatus is the reference signal generating means, and the function of the calibration value measuring unit 19 is the received calibration value calculating means. The functions of the units 15-1 to 15-B correspond to correction means. Further, the function of the calibration table update unit 40 corresponds to the table storage unit, and the cooperation function of the calibration value measurement unit 19 and the calibration table update unit 40 is the first reception calibration value update unit and the second reception calibration. Corresponds to the action value update means.

  In addition, the function of the calibration value measurement unit 57 of the array antenna transmission apparatus corresponds to the reception calibration value calculation unit, and the function of the calibration value multiplication units 53-1 to 53-B corresponds to the correction unit, and the calibration table update unit. The function 58 corresponds to the table storage means, and the cooperation function of the calibration value measurement unit 57 and the calibration table update unit 58 corresponds to the first transmission calibration value update means and the second transmission calibration value update means. .

It is a block diagram which shows the structural example of the array antenna receiver 1 in embodiment of this invention. It is a figure for demonstrating the production | generation method of the reference signal for calibration. It is a block diagram which shows the structural example of the array antenna receiver 2 in embodiment of this invention. It is a figure which shows the example of a production | generation of the calibration table in the array antenna receiver 2. FIG. It is a figure for demonstrating the update method (the 1) of the calibration table in the array antenna receiver 2. FIG. It is a figure for demonstrating the update method (the 2) of the calibration table in the array antenna receiver 2. FIG. It is a figure for demonstrating an AGC step size and a control period. It is a block diagram which shows the structural example of the transmitter 3 of the array antenna in embodiment of this invention. It is a figure which shows the example of a production | generation of the calibration table in the array antenna transmitter 3. FIG. It is a figure for demonstrating the update method (the 1) of the calibration table in the array antenna transmitter 3. FIG. It is a figure for demonstrating the update method (the 2) of the calibration table in the array antenna transmitter 3. FIG. It is a block diagram which shows the structural example of the conventional RF radio | wireless transmission circuit using an adaptive array antenna. It is a block diagram which shows the structural example of the conventional RF radio | wireless receiving circuit using an adaptive array antenna.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Array antenna receiver 3 Array antenna transmitter 11-1 to 11-B, 101-1 to 101-B Antenna element 12-1 to 12-B Duplexer 13-1 to 13-B RF receiver 14, 52 Measurement branch switch A
15-1 to 15-B, 53-1 to 53-B Calibration value multiplier 16, 54 Measurement branch selector switch B
DESCRIPTION OF SYMBOLS 17 Gain adjustment part 18 Calibration RF transmission part 19, 57 Calibration value measurement part 20 Calibration reference signal generator 31-1 to 31-B RF transmission part 40, 58 Calibration table update part 41 Automatic amplification gain storage 51 Inverse Fast Fourier Transform (IFFT)
55 RF receiver for calibration 56 Fast Fourier transform (FFT)
59 High Output Amplifier Output Level Storage Unit 102 Digital / Analog Signal Conversion Processing Unit 103 Quadrature Modulation Unit 104, 203 Mixer (Multiplier)
105 High Output Amplifier 202 Low Noise Amplifier 204 Band Limit Pass Filter 205 Automatic Amplification Gain Control Unit (AGC Circuit)
206 Quadrature detection unit 207 Reception level measurement unit 208 Analog / digital signal conversion processing unit

Claims (7)

In an array antenna receiving apparatus that includes an array antenna including a plurality of antenna elements and receives a multicarrier signal including a plurality of subcarriers ,
A reference signal generating means for generating a reference signal for calibration using a spread signal or a non-spread signal;
Reception of calculating the calibration value required to correct the amplitude deviation and phase deviation occurring between the branches of the receiver circuit provided corresponding to each of the plurality of antenna elements by using a reference signal said generated Calibration value calculation means;
Correction means for correcting amplitude deviation and phase deviation generated between the branches of the receiving circuit using the calculated calibration value;
The reception calibration value calculation means calculates a calibration value of the reception circuit between the branches for each amplification gain of the automatic amplification gain control unit provided in the reception circuit for each subcarrier, and uses the calculation result as a table. Table storage means for storing,
The correction means corrects amplitude deviation and phase deviation generated between the branches of the receiving circuit using calibration values stored in the table for each amplification gain, each subcarrier and each branch,
When the amplification gain of the automatic amplification gain control unit fluctuates, the reception calibration value calculation means forgets the calibration value before update with respect to the amplification gain after variation and the calibration value measured after variation of the amplification gain. An array antenna receiving apparatus , further comprising calibration value updating means for updating the calibration value of each branch and each subcarrier in the amplified gain after fluctuation by multiplying by a coefficient . In an array antenna receiving apparatus that includes an array antenna including a plurality of antenna elements and receives a multicarrier signal including a plurality of subcarriers,
A reference signal generating means for generating a reference signal for calibration using a spread signal or a non-spread signal;
Reception for calculating a calibration value necessary for correcting an amplitude deviation and a phase deviation generated between branches of a receiving circuit provided corresponding to each of the plurality of antenna elements, using the generated reference signal. Calibration value calculation means;
Correction means for correcting amplitude deviation and phase deviation generated between the branches of the receiving circuit using the calculated calibration value;
The reception calibration value calculation means calculates a calibration value of the reception circuit between the branches for each amplification gain of the automatic amplification gain control unit provided in the reception circuit for each subcarrier, and uses the calculation result as a table. Table storage means for storing,
The correction means corrects amplitude deviation and phase deviation generated between the branches of the receiving circuit using calibration values stored in the table for each amplification gain, each subcarrier and each branch,
When the amplification gain of the automatic amplification gain control unit fluctuates, the reception calibration value calculation means multiplies the calibration value of each amplification gain by a ratio before and after the calibration value is updated with respect to the amplified gain after the fluctuation. The array antenna receiving apparatus further comprising calibration value updating means for updating calibration values in each branch, each subcarrier and each amplification gain . In the array antenna receiver according to claim 1 or 2 ,
The reference signal generation means, when generating a reference signal using a spread signal, is predetermined for a spread signal that has been spread-modulated using a spread code orthogonal to the communication channel or a chip sequence that has been spread orthogonal to the communication channel An array antenna receiving apparatus that generates the reference signal using a chip pattern to which chip repetition of the number of repetitions is applied. In the array antenna receiver according to claim 1 or 2 ,
When generating a reference signal using a spread signal, the reference signal generating means uses a non-orthogonal spreading code for the communication channel and generates the reference signal for each subcarrier or for the bandwidth of all subcarriers. An array antenna receiving apparatus. In the array antenna receiver according to claim 1 or 2 ,
The reference signal generation means generates the reference signal at a center frequency for each subcarrier or a center frequency for all subcarriers when generating a reference signal using a non-spread signal. Receiver device. In an array antenna transmission apparatus that includes an array antenna including a plurality of antenna elements and transmits a multicarrier signal including a plurality of subcarriers ,
For each subcarrier, each every transmission output of the amplifier provided in the transmission circuit provided in correspondence of said plurality of antenna elements, needed to correct the amplitude deviation and phase deviation occurring between the branches of the transmission circuit Transmission calibration value calculating means for calculating a correct calibration value;
A table storage means you memorize as the table of the calculated calibration values,
Correction means for correcting amplitude deviation and phase deviation generated between the branches of the transmission circuit using the calibration values stored in the table;
The transmission calibration value calculation means includes a calibration value before update for the transmission output after the change and a calibration value measured after the change of the transmission output when the transmission output of the amplifier fluctuates. Is provided with calibration value update means for updating the calibration value of each branch and each subcarrier in the transmission output after fluctuation,
The correction means corrects amplitude deviation and phase deviation generated between branches of the transmission circuit using calibration values for each transmission output, each subcarrier, and each branch stored in the updated table. An array antenna transmitter characterized by the above.   In an array antenna transmission apparatus that includes an array antenna including a plurality of antenna elements and transmits a multicarrier signal including a plurality of subcarriers,
  Necessary for correcting amplitude deviation and phase deviation generated between branches of the transmission circuit for each subcarrier for each transmission output of the amplifier provided in the transmission circuit provided corresponding to each of the plurality of antenna elements. Transmission calibration value calculating means for calculating a correct calibration value;
  Table storage means for storing the calculated calibration values as a table;
  Correction means for correcting amplitude deviation and phase deviation generated between the branches of the transmission circuit using the calibration values stored in the table;
  The transmission calibration value calculation means multiplies the calibration value of each transmission output by the ratio before and after the update of the calibration value to the transmission output value after the change when the transmission output of the amplifier fluctuates. By means of this, it comprises a transmission calibration value update means for updating the calibration value in each branch, each subcarrier and each transmission output,
  The correction means corrects amplitude deviation and phase deviation generated between branches of the transmission circuit using calibration values for each transmission output, each subcarrier, and each branch stored in the updated table. An array antenna transmitter characterized by the above.

Images