JP2019004299A - Base station device and antenna control unit - Google Patents

Abstract

To prevent an increase in circuit scale.SOLUTION: A base station device comprises a plurality of branches and a first switch. The plurality of branches include a plurality of phase shifters that adjust the phase of transmission signals output from a filter on the subsequent stage of a power amplifier, and transmit the transmission signals in which the phase is adjusted by the plurality of phase shifters respectively from a plurality of antennas. When the relative phase difference between the antennas in a one-dimensional direction is corrected, the first switch switches the transmission signals fed back respectively from the plurality of branches. The plurality of branches each include a second switch. When the relative phase difference between the antennas in a two-dimensional direction is corrected, the second switch switches the transmission signals fed back respectively from the plurality of antennas.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a base station apparatus and an antenna control method.

  In recent years, due to an increase in traffic of wireless terminals such as smartphones and mobile terminals, traffic processed by one base station apparatus is also increasing. For this reason, measures are taken such as reducing the traffic volume per base station by finely installing a base station with a small coverage called a small cell.

  There is also a need for improved frequency utilization efficiency. For this reason, an increasing number of base station apparatuses have an antenna beam forming function that enables spatial multiplexing. By using antenna beam forming, radio waves can be radiated in a specific direction, so that radio wave interference can be avoided even if the same frequency is used for the same time.

The principle of an array antenna is used for antenna beam forming. FIG. 10 is a diagram showing the principle of the array antenna. Based on this principle, the relative phase difference Φ between antennas with respect to the angle at which radio waves are radiated is uniquely determined as shown in Equation (1).
Φ = ((2π · d) / λ) · sin θ (1)

  By giving this relative phase difference Φ to the transmission signal transmitted from each antenna, the radiation direction of the radio wave can be freely controlled. Phase adjustment is performed so that transmission signals transmitted from the respective antennas have a desired relative phase difference. This is called antenna calibration (ACAL). In FIG. 10, antennas are arranged on a one-dimensional array, but by arranging antennas on a two-dimensional array, the beam radiation direction can be controlled two-dimensionally.

  A configuration example for performing two-dimensional antenna beamforming is shown in FIG. FIG. 11 is a diagram illustrating a transmission unit (branch) of a conventional base station apparatus. Here, each of the plurality of branches is referred to as a branch 1040. The branch 1040 is provided with antennas 1006A to 1006D.

  The branch 1040 includes digital-to-analog converters (DAC) 1001A to 1001D, power amplifiers (PA) 1002A to 1002D, couplers 1003A to 1003D, and bandpass filters (BPF) 1004A to 1004D.

  Each of the DACs 1001A to 1001D converts the transmission signal into an analog signal and outputs the analog signal to the PAs 1002A to 1002D. PAs 1002A to 1002D receive transmission signals from DACs 1001A to 1001D, respectively, and amplify the power of the transmission signals.

  Couplers 1003A to 1003D output transmission signals from PAs 1002A to 1002D to BPFs 1004A to 1004D, respectively. Further, couplers 1003A to 1003D output the transmission signal as an ACAL feedback signal.

  The BPFs 1004A to 1004D pass signals in a specific frequency band with respect to the transmission signals from the couplers 1003A to 1003D, respectively, and attenuate signals in other frequency bands. The signals that have passed through the BPFs 1004A to 1004D are output from the antennas 1006A to 1006D as transmission signals, respectively.

JP-T-2006-503487

  However, in the conventional base station apparatus, for example, when eight branches 1040 are provided and four antennas are provided in each branch 1040, the total number of antennas is 32, but the signal of the feedback signal for ACAL 32 lines will be prepared. In addition, a total of 32 DACs, PAs, couplers, and BPFs are prepared. Thus, in the conventional base station apparatus, the same number of signal lines as the number of antennas, and the same number of DACs, PAs, couplers, and BPFs as the number of antennas are provided, so that the circuit scale increases.

  The technology disclosed in the present application suppresses an increase in circuit scale.

  In one aspect, the base station apparatus has a plurality of branches and a first switch. The plurality of branches includes a plurality of phase shifters that adjust the phase of the transmission signal output from the filter subsequent to the power amplifier, and transmits the transmission signals whose phases are adjusted by the plurality of phase shifters from the plurality of antennas, respectively. The first switch switches transmission signals fed back from each of the plurality of branches when correcting the relative phase difference between the antennas in the one-dimensional direction. Each of the plurality of branches has a second switch. The second switch switches transmission signals fed back from each of the plurality of antennas when correcting the relative phase difference between the antennas in the two-dimensional direction.

  In one aspect, an increase in circuit scale can be suppressed.

FIG. 1 is a diagram illustrating an example of an antenna configuration of the base station apparatus according to the embodiment. FIG. 2 is a diagram illustrating an example of a transmission unit (branch) of the base station apparatus according to the embodiment. FIG. 3 is a timing chart showing an example of the output operation of the phase shifter of FIG. FIG. 4 is a block diagram showing an example of the configuration of the phase shifter of FIG. FIG. 5 is an explanatory diagram showing an example of phase adjustment in the phase shifter of FIG. FIG. 6 is an explanatory diagram showing an example of phase adjustment in the phase shifter of FIG. FIG. 7 is a block diagram illustrating an example of the configuration of the base station apparatus according to the embodiment. FIG. 8 is a flowchart illustrating an example of the operation of the base station apparatus according to the embodiment. FIG. 9 is a diagram illustrating an example of a hardware configuration of the base station apparatus. FIG. 10 is a diagram showing the principle of the array antenna. FIG. 11 is a diagram illustrating a transmission unit (branch) of a conventional base station apparatus.

  Embodiments of a base station apparatus and an antenna control method disclosed in the present application will be described below in detail with reference to the drawings. The following examples do not limit the disclosed technology.

[Antenna configuration]
FIG. 1 is a diagram illustrating an example of an antenna configuration of the base station apparatus 100 according to the embodiment.

  Base station apparatus 100 includes a plurality of transmission units (branches) # 0 to # 7. In each of the plurality of branches # 0 to # 7, phase shifters 5A to 5D and antennas 6A to 6D are provided. Antennas 6A to 6D are provided at the outputs of the phase shifters 5A to 5D, respectively.

  Here, the direction in which the plurality of branches # 0 to # 7 are arranged (horizontal direction X in FIG. 1) is referred to as a one-dimensional direction. Further, in each of the branches # 0 to # 7, the direction in which the antennas 6A to 6D are arranged (vertical direction Y in FIG. 1) is called a two-dimensional direction, which is different from the one-dimensional direction. The antennas 6A to 6D may be referred to as an antenna group.

[Configuration of transmitter]
FIG. 2 is a diagram illustrating an example of the transmission unit (branch) 40 of the base station apparatus 100 according to the embodiment. Here, each of the plurality of branches # 0 to # 7 may be referred to as a branch 40.

  The branch 40 is sequentially switched as each branch # 0 to # 7 by a switch described later. In addition to the antennas 6A to 6D, the branch 40 is provided with an analog processing unit 10 and directional couplers 7A to 7D. Here, the antennas 6A to 6D are provided in the directional couplers 7A to 7D, respectively.

  The analog processing unit 10 includes a digital-analog converter (DAC) 1, a power amplifier (PA) 2, a coupler (or circulator) 3, a band-pass filter (BPF) 4, phase shifters 5A to 5D, switches ( SW) 8.

  The DAC 1 receives a transmission signal from a digital processing unit described later. The DAC 1 converts the transmission signal into an analog signal and outputs it to PA2.

  PA2 receives the transmission signal from DAC1. PA 2 amplifies the power of the transmission signal and outputs it to coupler 3.

  The coupler 3 receives a transmission signal from the PA2. The coupler 3 outputs a transmission signal to the BPF 4. Further, the coupler 3 outputs the transmission signal to the feedback path DPD-FB.

  The transmission signal (feedback signal) output to the feedback path DPD-FB is used for DPD (Digital Pre-Distortion) which is a calculation process. The feedback path DPD-FB is sequentially switched as a feedback path DPD-FB of each branch # 0 to # 7 by a switch described later. DPD corrects nonlinear distortion characteristics due to PA2 and the phase fluctuation of the transmission signal generated up to the output end of PA2. Details of the DPD will be described later.

  The BPF 4 receives a transmission signal from the coupler 3. The BPF 4 passes signals in a specific frequency band with respect to the transmission signal and attenuates signals in other frequency bands. The signal that has passed through the BPF 4 is output as a transmission signal to the phase shifters 5A to 5D.

  The phase shifters 5A to 5D receive the transmission signal from the BPF 4. Each of the phase shifters 5A to 5D adjusts the phase of the transmission signal in accordance with, for example, control signals CTR5A to CTR5D output from a digital processing unit, which will be described later, and converts the transmission signal whose phase is adjusted to the directional coupler 7A. Output to ~ 7D.

  Directional couplers 7A to 7D receive transmission signals from phase shifters 5A to 5D, respectively. Directional couplers 7A to 7D output transmission signals from antennas 6A to 6D, respectively. In addition, each of the directional couplers 7A to 7D outputs a transmission signal to SW8.

  SW8 receives transmission signals from the directional couplers 7A to 7D. For example, the SW8 sequentially outputs transmission signals output from the directional couplers 7A to 7D to the feedback path ACAL-FB in accordance with a control signal CTR8 output from a baseband processing unit described later.

  The transmission signal (feedback signal) output to the feedback path ACAL-FB is used for ACAL (Antenna Calibration) which is a calculation process. The feedback path ACAL-FB is sequentially switched as a feedback path ACAL-FB of each branch # 0 to # 7 by a switch described later. As will be described later, as the execution of ACAL, a one-dimensional ACAL and a two-dimensional ACAL are executed.

  Here, the relative phase difference between the antenna 6A of the branch # 0 and the antenna 6A of the branches # 1 to # 7 is corrected to a desired relative phase difference by the one-dimensional ACAL. That is, the relative phase difference of the transmission signal output from the antenna 6A of the branches # 1 to # 7 with respect to the transmission signal output from the antenna 6A of the branch # 0 is corrected to a desired relative phase difference by the one-dimensional ACAL. The

  In addition, the relative phase difference between the antenna 6A and the antennas 6B to 5D is corrected to a desired relative phase difference in each branch # 0 to # 7 by the two-dimensional ACAL. That is, the relative phase difference of the transmission signals output from the antennas 6B to 5D with respect to the transmission signals output from the antenna 6A is corrected to a desired relative phase difference in each branch # 0 to # 7 by the two-dimensional ACAL. The

  Details of the one-dimensional ACAL and the two-dimensional ACAL will be described later.

  FIG. 3 is a timing chart showing an example of the output operation of the phase shifters 5A to 5D in FIG.

  As described above, the control signals CTR5A to CTR5D are supplied to the phase shifters 5A to 5D, respectively. First, the phase shifter 5A adjusts the phase of the transmission signal in accordance with the control signal CTR5A, and outputs the transmission signal with the adjusted phase to the directional coupler 7A. Next, the phase shifter 5B adjusts the phase of the transmission signal in accordance with the control signal CTR5B, and outputs the transmission signal whose phase has been adjusted to the directional coupler 7B. Next, the phase shifter 5C adjusts the phase of the transmission signal in accordance with the control signal CTR5C, and outputs the transmission signal whose phase has been adjusted to the directional coupler 7C. Next, the phase shifter 5D adjusts the phase of the transmission signal in accordance with the control signal CTR5D, and outputs the transmission signal whose phase has been adjusted to the directional coupler 7D.

  As described above, the SW8 switches the outputs of the phase shifters 5A to 5D, that is, the outputs of the directional couplers 7A to 7D, according to the control signal CTR8. The control signal CTR8 represents one of the first to fourth values. SW8 has first to fourth switch portions respectively corresponding to outputs of the phase shifters 5A to 5D (outputs of the directional couplers 7A to 7D), and each of the first to fourth switch portions has a first one. A fourth value is assigned. The outputs of the phase shifters 5A to 5D (outputs of the directional couplers 7A to 7D) are sequentially extracted by turning on the first to fourth switch sections of the SW 8 in order according to the value represented by the control signal CTR8. Is done. That is, the transmission signals from the phase shifters 5A to 5D (transmission signals from the directional couplers 7A to 7D) are sequentially output to the feedback path ACAL-FB.

  In the base station apparatus 100 according to the embodiment, when the phase difference between the antennas in the one-dimensional direction is corrected, output feedback of each of the plurality of branches # 0 to # 7 is switched by a switch described later. In each of the plurality of branches # 0 to # 7, when correcting the phase difference between the antennas in the two-dimensional direction, the output feedback of the plurality of antennas 6A to 6D is used as the output of the plurality of phase shifters 5A to 5D. Switch with. Here, in the conventional base station apparatus (see FIG. 11), for example, when eight branches 1040 are provided and four antennas are provided in each branch 1040, the number of antennas is 32 in total. 32 signal lines for feedback signals for ACAL are also prepared. Thus, in the conventional base station apparatus, since the same number of signal lines as the number of antennas are provided, the circuit scale increases. On the other hand, in the base station apparatus 100 according to the embodiment, for example, when eight branches 40 are provided and each branch 40 is provided with four antennas, by providing SW8 in each branch 40, the feedback signal for ACAL is provided. One signal line may be provided. That is, in the base station apparatus 100 according to the embodiment, since it is only necessary to provide the same number of signal lines as the number of branches 40, an increase in circuit scale can be suppressed.

  Furthermore, in the base station apparatus 100 of the present embodiment, a plurality of phase shifters 5A to 5D are provided in each of the plurality of branches # 0 to # 7. Here, in the conventional base station apparatus (see FIG. 11), for example, when eight branches 1040 are provided and four antennas are provided in each branch 1040, the number of antennas is 32 in total. A total of 32 DACs, PAs, couplers, and BPFs are prepared. As described above, in the conventional base station apparatus, the same number of DACs, PAs, couplers, and BPFs as antennas are provided, so that the circuit scale increases. On the other hand, in the base station apparatus 100 according to the embodiment, for example, when eight branches 40 are provided and each branch 40 is provided with four antennas, by providing four phase shifters in each branch 40, DAC, PA A total of eight couplers and BPFs may be provided. That is, in the base station apparatus 100 according to the embodiment, it is only necessary to provide the same number of DACs, PAs, couplers, and BPFs as the number of branches 40, so that an increase in circuit scale can be suppressed.

  Further, the base station apparatus 100 according to the embodiment is configured such that the directional couplers 7A to 7D are provided at the antenna ends (end portions of 6A to 6D), and a transmission signal is extracted from the antenna end as a feedback signal for ACAL. Yes. Here, in the case of high power handled by the macro cell, the transmission signals output from the phase shifters 5A to 5D may be distorted by the directional couplers 7A to 7D. On the other hand, in the case of power handled by a small cell, the transmission signals output from the phase shifters 5A to 5D can be extracted as ACAL feedback signals without being distorted by the directional couplers 7A to 7D. In the conventional base station apparatus, transmission signals are taken out as feedback signals for ACAL from couplers 1003A to 1003D provided before 1006A to 1006D (see FIG. 11). In this case, since the configuration (BPF 1004A to 1004D) from the couplers 1003A to 1003D to the antenna ends (end portions of 1006A to 1006D) is not considered, ACAL cannot be performed with high accuracy. On the other hand, in the base station apparatus 100 according to the embodiment, the directional couplers 7A to 7D are provided at the antenna ends (end portions of 6A to 6D), and the transmission signal is extracted from the antenna end as a feedback signal for ACAL. It can be performed with high accuracy.

[Configuration of phase shifter in transmitter]
FIG. 4 is a block diagram illustrating an example of the configuration of the phase shifters 5A to 5D in FIG. Each of the phase shifters 5A to 5D includes a hybrid coupler 51, switches (SW) 52 and 53, and capacitors 54A to 54D and 55A to 55D.

  The hybrid coupler 51 has four ports “1”, “2”, “3”, and “4”. Port “1” is connected to the output of the BPF, and port “4” is connected to the directional coupler. The port “2” is connected to one end of the capacitors 54A to 54D, and the other end of the capacitors 54A to 54D is grounded. The port “3” is connected to one end of the capacitors 55A to 55D, and the other end of the capacitors 55A to 55D is grounded.

  Each of the capacitors 54A to 54D has a different capacitance value. Capacitors 55A to 55D have different capacitance values. On the other hand, the capacitors 54A to 54D have the same capacitance values as the capacitors 55A to 55D, respectively. Thereby, the capacitors 54A to 54D and the capacitors 55A to 55D are controlled in common.

  5 and 6 are explanatory diagrams showing an example of phase adjustment in the phase shifters 5A to 5D in FIG.

  As a property of the hybrid coupler 51, when a transmission signal is input to the port “1”, a transmission signal with a phase delay of 90 degrees appears at the port “2”, and a transmission signal with a phase delay of 180 degrees appears at the port “3”. A signal appears and no signal appears at port "4". By providing capacitors with the same capacitance value at the ports “2” and “3”, the phase difference between the incident wave and the reflected wave at the ports “2” and “3” becomes equal. Let this delay amount be θ. For example, in FIG. 5, a transmission signal between ports “2” and “4” has a phase delay of 180 degrees, and in FIG. 6, a phase delay of 90 degrees between ports “3” and “4”. As a result, the transmission signal input to the port “1” is output as a transmission signal having a phase delay of (270 degrees + θ) at the port “4”. θ can be changed by the capacitance values of the capacitors 54A to 54D and 55A to 55D connected to the ports “2” and “3”, respectively.

  In the phase shifters 5A to 5D in the base station apparatus 100 according to the embodiment, the reflected wave signal is distorted by the capacitor in the case of a large power handled by the macro cell, but the reflected wave is not produced by the power handled by the small cell. The signal will not be distorted. There is also a phase shifter that adjusts the phase by changing the wiring length of the pattern. In such a phase shifter, the wiring pattern needs to be routed, and the substrate area increases as the number of antennas increases. Since the phase shifters 5A to 5D in the base station apparatus 100 according to the embodiment have a variable capacitor configuration, they can be realized on a small scale even if the number of antennas increases.

[Configuration of base station apparatus]
FIG. 7 is a block diagram illustrating an example of the configuration of the base station apparatus according to the embodiment. The base station apparatus 100 further includes a baseband processing unit 60, a digital processing unit 20, switches (SW) 11 to 13, and an analog / digital converter (ADC) 14.

  The digital processing unit 20 includes a correction unit 30, a selector 21, a demodulation unit 22, a calculation unit 23, and a switch (SW) 24. Here, the transmission unit (branch) 40 is provided with a correction unit 30 in addition to the analog processing unit 10, the antennas 6A to 6D, and the directional couplers 7A to 7D.

  The correction unit 30 includes multiplication units 31 and 32, a DPD lookup table (DPD LUT) 33, a one-dimensional ACAL lookup table (one-dimensional ACAL LUT) 34, a two-dimensional ACAL control unit 35, and a switch (SW). 36.

  The multiplier 31 receives a transmission signal that is a digital signal output from the baseband processor 60. The multiplier 31 applies the one-dimensional ACAL correction coefficient stored in the one-dimensional ACAL LUT 34 to the transmission signal. That is, the one-dimensional ACAL correction coefficient stored in the one-dimensional ACAL LUT 34 and the transmission signal are multiplied by the multiplication unit 31. Thereby, the relative phase difference between the antenna 6A of the branch # 0 and the antenna 6A of the branches # 1 to # 7 is corrected to a desired relative phase difference. That is, the relative phase difference of the transmission signal output from the antenna 6A of the branches # 1 to # 7 with respect to the transmission signal output from the antenna 6A of the branch # 0 is corrected to a desired relative phase difference. Multiplier 31 outputs the corrected transmission signal to multiplier 32.

  The multiplier 32 receives a transmission signal from the multiplier 31. The multiplier 32 applies the DPD correction coefficient stored in the DPD LUT 33 to the transmission signal. That is, the multiplication unit 32 multiplies the DPD correction coefficient stored in the DPD LUT 33 and the transmission signal. As a result, the nonlinear distortion characteristic due to PA2 and the phase fluctuation of the transmission signal generated up to the output end of PA2 are corrected. The multiplier 32 outputs the corrected transmission signal to the DAC 1.

  The DAC 1 converts the transmission signal from the multiplication unit 32 into an analog signal and outputs it to the PA 2. PA 2 amplifies the power of the transmission signal from DAC 1 and outputs the amplified signal to coupler 3. The coupler 3 outputs the transmission signal from the PA 2 to the BPF 4 and outputs it to the SW 13 via the SW 11 and the feedback path DPD-FB.

  The SW 11 is provided on the feedback path DPD-FB, and switches branches according to, for example, the control signal CTR 11 output from the baseband processing unit 60. The control signal CTR11 represents one of the first to eighth values. The SW 11 has first to eighth switch units respectively corresponding to a plurality of branches # 0 to # 7, and first to eighth values are assigned to the first to eighth switch units, respectively. . According to the value represented by the control signal CTR11, the first to eighth switch sections of the SW11 are sequentially turned on, so that the feedback paths DPD-FB of the branches # 0 to # 7 are sequentially enabled. That is, in each branch # 0 to # 7, the coupler 3 and the SW13 are connected via the SW11 and the feedback path DPD-FB.

  The BPF 4 passes a signal in a specific frequency band with respect to the transmission signal from the coupler 3 and attenuates signals in other frequency bands. The signal that has passed through the BPF 4 is output as a transmission signal to the phase shifters 5A to 5D.

  The phase shifters 5A to 5D receive the transmission signal from the BPF 4. The phase shifters 5A to 5D adjust the phase of the transmission signal in order, for example, in accordance with the control signals CTR5A to CTR5D output from the two-dimensional ACAL control unit 35, respectively. To the sex couplers 7A to 7D.

  The directional couplers 7A to 7D output the transmission signals from the phase shifters 5A to 5D from the antennas 6A to 6D, respectively, and output the transmission signals to the SW8. For example, in accordance with the control signal CTR8 output from the baseband processing unit 60, the SW8 sequentially transmits transmission signals from the phase shifters 5A to 5D, that is, transmission signals from the directional couplers 7A to 7D. Output to SW13 via path ACAL-FB.

  The SW 12 is provided on the feedback path ACAL-FB, and switches branches according to, for example, the control signal CTR 12 output from the baseband processing unit 60. The control signal CTR12 represents one of the first to eighth values. The SW 12 has first to eighth switch units respectively corresponding to the plurality of branches # 0 to # 7, and the first to eighth values are assigned to the first to eighth switch units, respectively. . According to the value represented by the control signal CTR12, the first to eighth switch sections of the SW12 are sequentially turned on, so that the feedback paths ACAL-FB of the branches # 0 to # 7 are sequentially enabled. That is, in each branch # 0 to # 7, the output of the directional coupler (the output of the phase shifter) and SW13 are connected via SW8, SW12 and the feedback path ACAL-FB.

  For example, the SW 13 switches the feedback path to time division according to the control signal CTR 13 output from the baseband processing unit 60. The control signal CTR13 represents a first value or a second value. For example, when the control signal CTR13 represents the first value, the SW13 selects the feedback path DPD-FB. In this case, the SW 13 outputs a transmission signal fed back from the output of the PA 2 via the coupler 3, SW 11 and the feedback path DPD-FB to the ADC 14. When the control signal CTR13 represents the second value, the SW13 selects the feedback path ACAL-FB. In this case, the SW 13 outputs the transmission signal fed back from the output of the BPF 4 via the phase shifter, the directional coupler, SW 8 and SW 12, and the feedback path ACAL-FB to the ADC 14.

  The ADC 14 receives a transmission signal from the SW 13. The ADC 14 converts the transmission signal into a digital signal and outputs the digital signal to the demodulation unit 22.

  The demodulator 22 receives a transmission signal from the ADC 14. The demodulator 22 demodulates the transmission signal and outputs it to the calculator 23.

  The selector 21 selects a transmission signal according to the control signal. For example, when the control signal represents the first value, the selector 21 selects the first transmission signal. When the control signal represents the second value, the selector 21 selects the second transmission signal. The first transmission signal is a transmission signal that is output from the multiplier 31 and before being input to the multiplier 32. The second transmission signal is a transmission signal that is output from the baseband processing unit 60 and before being input to the multiplication unit 31. Therefore, when the control signal represents the first value, the selector 21 outputs the first transmission signal to the calculation unit 23. Further, when the control signal represents the second value, the selector 21 outputs the second transmission signal to the calculation unit 23.

  The SW 24 is provided between the calculation unit 23 and the correction unit 30 and switches branches according to a control signal CTR 24 output from the baseband processing unit 60, for example. The control signal CTR24 represents one of the first to eighth values. The SW 24 has first to eighth switch units respectively corresponding to the plurality of branches # 0 to # 7, and the first to eighth values are assigned to the first to eighth switch units, respectively. . According to the value represented by the control signal CTR24, the first to eighth switch sections of the SW24 are sequentially turned on, so that the respective branches # 0 to # 7 are sequentially enabled. That is, the calculation unit 23 and the correction unit 30 are connected in each branch # 0 to # 7.

  The SW 36 of the correction unit 30 selects one of the DPD LUT 33, the one-dimensional ACAL LUT 34, and the two-dimensional ACAL control unit 35 according to the control signal CTR 36 output from the baseband processing unit 60, for example. The control signal CTR36 represents one of the first to third values. The SW 36 has first to third switch units corresponding to the DPD LUT 33, the one-dimensional ACAL LUT 34, and the two-dimensional ACAL control unit 35, and the first to third switch units respectively include the first to third switches. A value has been assigned. For example, when the control signal CTR36 represents the first value, the SW36 selects the DPD LUT33, and the calculation unit 23 and the DPD LUT33 are connected via the SW24 and SW36. When the control signal CTR36 represents the second value, the SW 36 selects the one-dimensional ACAL LUT 34, and the arithmetic unit 23 and the one-dimensional ACAL LUT 34 are connected via the SW 24 and SW 36. When the control signal CTR36 represents the third value, the SW 36 selects the two-dimensional ACAL control unit 35, and the calculation unit 23 and the two-dimensional ACAL control unit 35 are connected via SW24 and SW36.

  The calculation unit 23 includes an LMS calculation processing unit 231 and an error extraction processing unit 232. The arithmetic unit 23 is an example of an arithmetic circuit. The calculation unit 23 executes DPD, one-dimensional direction ACAL, and two-dimensional direction ACAL. In the two-dimensional ACAL, the two-dimensional ACAL control unit 35 controls the phase shifters 5A to 5D.

[DPD]
In the DPD, in each branch # 0 to # 7, an output error of PA2, which will be described later, is used to correct distortion characteristics due to PA2 and a variation in the phase of the transmission signal that occurs up to the output end of PA2.

  For example, when the branch is branch # 0, the error extraction processing unit 232 receives the first transmission signal from the selector 21 (the transmission signal output from the multiplication unit 31 and before being input to the multiplication unit 32). The first transmission signal is received from the demodulator 22. The first transmission signal from the demodulation unit 22 is a transmission signal fed back from the PA 2 via the coupler 3, SW 11, feedback path DPD-FB, SW 13, ADC 14, and demodulation unit 22. In this case, the error extraction processing unit 232 extracts an error between the first transmission signal from the selector 21 and the first transmission signal from the demodulation unit 22 as an output error of PA2, and performs an LMS calculation process on the output error of PA2. To the unit 231.

  The LMS arithmetic processing unit 231 receives the output error of PA2 from the error extraction processing unit 232. In this case, the LMS arithmetic processing unit 231 performs DPD correction so that the output error of PA2 becomes zero by arithmetic processing using a Least Mean Square (LMS) algorithm (hereinafter referred to as LMS arithmetic processing), for example. Calculate the coefficient. That is, the LMS arithmetic processing unit 231 calculates a DPD correction coefficient for correcting the nonlinear distortion characteristic due to PA2 and the phase fluctuation of the transmission signal generated up to the output end of PA2 based on the output error of PA2. Calculate. The LMS calculation processing unit 231 stores the calculated DPD correction coefficient in the DPD LUT 33 via SW24 and SW36. That is, the LMS arithmetic processing unit 231 updates the DPD LUT 33.

  Here, the DPD correction coefficient stored in the DPD LUT 33 and the transmission signal are multiplied by the multiplication unit 32, so that the distortion characteristics due to PA2 and the phase fluctuation of the transmission signal generated up to the output terminal of PA2 are obtained. It is corrected.

[One-dimensional ACAL]
In the one-dimensional ACAL, the relative phase difference between the antenna 6A of the branch # 0 and the antenna 6A of the branches # 1 to # 7 is used by using an output error of an antenna 6A described later in the plurality of branches # 0 to # 7. Is corrected.

  For example, when the branch is branch # 1, the error extraction processing unit 232 outputs the second transmission signal from the selector 21 (the transmission signal output from the baseband processing unit 60 and before being input to the multiplication unit 31). And the second transmission signal is received from the demodulator 22. Here, the second transmission signal from the demodulation unit 22 is transmitted from the BPF 4 via the phase shifter 5A, the antenna 6A, the directional couplers 7A, SW8, SW12, the feedback path ACAL-FB, SW13, ADC 14, and the demodulation unit 22. This is a feedback transmission signal. In this case, the error extraction processing unit 232 extracts an error between the second transmission signal from the selector 21 and the second transmission signal from the demodulation unit 22 as an output error of the antenna 6A, and outputs the output error of the antenna 6A to the LMS. The result is output to the arithmetic processing unit 231.

  The LMS arithmetic processing unit 231 receives the output error of the antenna 6A from the error extraction processing unit 232. In this case, the LMS arithmetic processing unit 231 calculates the one-dimensional ACAL correction coefficient so that the relative phase difference of the transmission signal of the branch # 1 with respect to the transmission signal of the branch # 0 becomes a desired relative phase difference by the LMS arithmetic processing. . For example, the LMS arithmetic processing unit 231 obtains a difference between the output error of the antenna 6A in the branch # 0 and the output error of the antenna 6A in the branch # 1. Then, based on the difference, the LMS arithmetic processing unit 231 determines a relative phase difference of the transmission signal output from the antenna 6A of the branch # 1 with respect to the transmission signal output from the antenna 6A of the branch # 0. A one-dimensional ACAL correction coefficient for correcting to is calculated. The LMS arithmetic processing unit 231 stores the calculated one-dimensional ACAL correction coefficient in the one-dimensional ACAL LUT 34 via SW24 and SW36. That is, the LMS arithmetic processing unit 231 updates the one-dimensional ACAL LUT 34.

  Here, the multiplication unit 31 multiplies the one-dimensional ACAL correction coefficient stored in the one-dimensional ACAL LUT 34 and the transmission signal, so that, for example, the relative relationship between the antenna 6A of the branch # 0 and the antenna 6A of the branch # 1 The phase difference is corrected to a desired relative phase difference.

  Similarly, even when the branches are branches # 2 to # 7, the one-dimensional ACAL correction coefficient is calculated based on the output error of the antenna 6A in the branch # 0, and the branch # 0 antenna 6A and the branches # 2 to # 7 are calculated. 7 relative to the antenna 6A is corrected.

[ACAL in two dimensions]
In the two-dimensional ACAL, in each branch # 0 to # 7, the relative phase difference between the antenna 6A and the antennas 6B to 6D is corrected using output errors of phase shifters 5A to 5D described later.

  For example, when the branch is branch # 0, the error extraction processing unit 232 outputs the second transmission signal from the selector 21 (the transmission signal output from the baseband processing unit 60 and before being input to the multiplication unit 31). And the second transmission signal is received from the demodulator 22. Here, the second transmission signal from the demodulation unit 22 is transmitted from the BPF 4 via the phase shifter 5B, the antenna 6B, the directional couplers 7B, SW8, SW12, the feedback path ACAL-FB, SW13, ADC 14, and the demodulation unit 22. This is a feedback transmission signal. In this case, the error extraction processing unit 232 extracts an error between the second transmission signal from the selector 21 and the second transmission signal from the demodulation unit 22 as an output error of the antenna 6B, and converts the output error of the antenna 6B to the LMS. The result is output to the arithmetic processing unit 231.

  The LMS arithmetic processing unit 231 receives the output error of the antenna 6B from the error extraction processing unit 232. In this case, the LMS arithmetic processing unit 231 performs two-dimensional ACAL correction so that the relative phase difference of the transmission signal output from the antenna 6B with respect to the transmission signal output from the antenna 6A becomes a desired relative phase difference by the LMS arithmetic processing. Calculate the coefficient. For example, the LMS arithmetic processing unit 231 obtains a difference between the output error of the antenna 6A and the output error of the antenna 6B. Based on the difference, the LMS arithmetic processing unit 231 performs a two-dimensional ACAL for correcting the relative phase difference of the transmission signal output from the antenna 6B with respect to the transmission signal output from the antenna 6A to a desired relative phase difference. Calculate the correction factor. The LMS arithmetic processing unit 231 outputs the calculated two-dimensional ACAL correction coefficient to the two-dimensional ACAL control unit 35 via SW24 and SW36.

  The two-dimensional ACAL control unit 35 receives a two-dimensional ACAL correction coefficient from the LMS arithmetic processing unit 231. The two-dimensional ACAL control unit 35 includes the two-dimensional ACAL correction coefficient in the control signal CTR5B so that the relative phase difference of the transmission signal output from the antenna 6B with respect to the transmission signal output from the antenna 6A is a desired relative phase difference. The phase shifter 5B is controlled so that

  Similarly, in the case of the antennas 6C and 5D, the two-dimensional ACAL correction coefficient is calculated based on the output error of the antenna 6A, and the relative phase difference between the antenna 6A and the antennas 6C and 6D is corrected.

  Here, the above-described ACAL control is performed by a self-control by a remote radio head (hereinafter abbreviated as “RRH”) and a baseband unit (hereinafter abbreviated as “BBU”). Both dependent controls are possible. The baseband processing unit 60 is an example of BBU.

[Operation example of base station]
Next, processing of the base station apparatus 100 according to the embodiment will be described. FIG. 8 is a flowchart illustrating an example of the operation of the base station apparatus 100 according to the embodiment.

  For example, the baseband processing unit 60 sets 1 to the constant N (step S1). Here, N represents any one of “1” to “8”, and “1” to “8” are assigned to the plurality of branches # 0 to # 7 as first to eighth values, respectively.

  First, DPD is executed for the branch # 0 which is the first branch (step S2).

  In step S2, the path of feedback path DPD-FB is first selected by SW13. In this case, the selector 21 outputs the first transmission signal (the transmission signal output from the multiplier 31 and before being input to the multiplier 32) to the error extraction processor 232. The first transmission signal is output from the demodulation unit 22 to the error extraction processing unit 232. The first transmission signal from the demodulation unit 22 is a transmission signal fed back from the PA 2 via the coupler 3, SW 11, feedback path DPD-FB, SW 13, ADC 14, and demodulation unit 22. The SW 36 selects the DPD LUT 33.

  The error extraction processing unit 232 receives the first transmission signal from the selector 21 and receives the first transmission signal from the demodulation unit 22. The error extraction processing unit 232 extracts an error between the first transmission signal from the selector 21 and the first transmission signal from the demodulation unit 22 as an output error of PA2. The LMS arithmetic processing unit 231 performs LMS arithmetic processing on the output error of PA2. By this calculation process, the DPD correction coefficient for correcting the nonlinear distortion characteristic by PA2 and the phase fluctuation of the transmission signal generated up to the output terminal of PA2 is calculated. The LMS arithmetic processing unit 231 updates the DPD LUT 33 by storing the DPD correction coefficient in the DPD LUT 33 via the SW 24 and SW 36. The multiplication unit 32 multiplies the DPD correction coefficient stored in the DPD LUT 33 and the transmission signal, thereby correcting the distortion characteristics due to PA2 and the phase fluctuation of the transmission signal generated up to the output terminal of PA2. .

  If the branch is the first branch (branch # 0) (step S3: Yes), the one-dimensional ACAL (step S4) is skipped. In branch # 0, which is the first branch, since the output error of antenna 6A is used as a reference, it is not necessary to perform one-dimensional ACAL on branch # 0. Therefore, when N = 1, that is, when the branch is the first branch (branch # 0), the one-dimensional ACAL (step S4) is skipped.

  Here, even when ACAL in the one-dimensional direction (step S4) is skipped, the path of the feedback path ACAL-FB is selected by SW13 in step S3. In this case, the selector 21 outputs the second transmission signal (the transmission signal output from the baseband processing unit 60 and before being input to the multiplication unit 31) to the error extraction processing unit 232. The second transmission signal is output from the demodulation unit 22 to the error extraction processing unit 232. The second transmission signal from the demodulator 22 is fed back from the BPF 4 via the phase shifter 5A, antenna 6A, directional coupler 7A, SW8, SW12, feedback path ACAL-FB, SW13, ADC 14, and demodulator 22. It is a transmission signal. The error extraction processing unit 232 receives the second transmission signal from the selector 21 and receives the second transmission signal from the demodulation unit 22. The error extraction processing unit 232 extracts an error between the second transmission signal from the selector 21 and the second transmission signal from the demodulation unit 22 as an output error of the antenna 6A.

  Next, ACAL in the two-dimensional direction is executed for the first branch (branch # 0) (steps S5 to S7). Also in steps S5 to S7, the path of the feedback path ACAL-FB is selected by SW13.

  In step S <b> 5, the selector 21 outputs the second transmission signal (the transmission signal output from the baseband processing unit 60 and before being input to the multiplication unit 31) to the error extraction processing unit 232. The second transmission signal is output from the demodulation unit 22 to the error extraction processing unit 232. The second transmission signal from the demodulator 22 is fed back from the BPF 4 via the phase shifter 5B, antenna 6B, directional coupler 7B, SW8, SW12, feedback path ACAL-FB, SW13, ADC14, and demodulator 22. It is a transmission signal.

  The error extraction processing unit 232 receives the second transmission signal from the selector 21 and receives the second transmission signal from the demodulation unit 22. The error extraction processing unit 232 extracts an error between the second transmission signal from the selector 21 and the second transmission signal from the demodulation unit 22 as an output error of the antenna 6B. The LMS arithmetic processing unit 231 calculates a two-dimensional ACAL correction coefficient by LMS arithmetic processing so that the relative phase difference of the transmission signal output from the antenna 6B with respect to the transmission signal output from the antenna 6A becomes a desired relative phase difference. To do. The LMS arithmetic processing unit 231 outputs the two-dimensional ACAL correction coefficient to the two-dimensional ACAL control unit 35 via SW24 and SW36. The two-dimensional ACAL control unit 35 controls the phase shifter 5B so that the relative phase difference between the antenna 6A and the antenna 6B becomes a desired relative phase difference by including the two-dimensional ACAL correction coefficient in the control signal CTR5B. To do.

  In step S <b> 6, the selector 21 outputs the second transmission signal (the transmission signal output from the baseband processing unit 60 and before being input to the multiplication unit 31) to the error extraction processing unit 232. The second transmission signal is output from the demodulation unit 22 to the error extraction processing unit 232. The second transmission signal from the demodulator 22 is fed back from the BPF 4 via the phase shifter 5C, the antenna 6C, the directional coupler 7C, SW8, SW12, the feedback path ACAL-FB, SW13, ADC14, and the demodulator 22. It is a transmission signal.

  The error extraction processing unit 232 receives the second transmission signal from the selector 21 and receives the second transmission signal from the demodulation unit 22. The error extraction processing unit 232 extracts an error between the second transmission signal from the selector 21 and the second transmission signal from the demodulation unit 22 as an output error of the antenna 6C. The LMS arithmetic processing unit 231 calculates a two-dimensional ACAL correction coefficient by LMS arithmetic processing so that the relative phase difference of the transmission signal output from the antenna 6C with respect to the transmission signal output from the antenna 6A becomes a desired relative phase difference. To do. The LMS arithmetic processing unit 231 outputs the two-dimensional ACAL correction coefficient to the two-dimensional ACAL control unit 35 via SW24 and SW36. The two-dimensional ACAL control unit 35 controls the phase shifter 5C so that the relative phase difference between the antenna 6A and the antenna 6C becomes a desired relative phase difference by including the two-dimensional ACAL correction coefficient in the control signal CTR5C. To do.

  In step S <b> 7, the selector 21 outputs the second transmission signal (the transmission signal output from the baseband processing unit 60 and before being input to the multiplication unit 31) to the error extraction processing unit 232. The second transmission signal is output from the demodulation unit 22 to the error extraction processing unit 232. The second transmission signal from the demodulator 22 is fed back from the BPF 4 via the phase shifter 5D, the antenna 6D, the directional coupler 7D, SW8, SW12, the feedback path ACAL-FB, SW13, ADC14, and the demodulator 22. It is a transmission signal.

  The error extraction processing unit 232 receives the second transmission signal from the selector 21 and receives the second transmission signal from the demodulation unit 22. The error extraction processing unit 232 extracts an error between the second transmission signal from the selector 21 and the second transmission signal from the demodulation unit 22 as an output error of the antenna 6D. The LMS calculation processing unit 231 calculates a two-dimensional ACAL correction coefficient by LMS calculation processing so that the relative phase difference of the transmission signal output from the antenna 6D with respect to the transmission signal output from the antenna 6A becomes a desired relative phase difference. To do. The LMS arithmetic processing unit 231 outputs the two-dimensional ACAL correction coefficient to the two-dimensional ACAL control unit 35 via SW24 and SW36. The two-dimensional ACAL control unit 35 controls the phase shifter 5D so that the relative phase difference between the antenna 6A and the antenna 6D becomes a desired relative phase difference by including the two-dimensional ACAL correction coefficient in the control signal CTR5C. To do.

  Next, the baseband processing unit 60 adds 1 to the constant N (step S8). If N does not exceed 8 (step S9: No), step S2 is executed.

  For example, DPD is executed for the branch # 1, which is the second branch (step S2).

  Next, when the branch is the second branch (branch # 1) (step S3: No), the one-dimensional ACAL (step S4) is executed.

  In step S4, the path of feedback path ACAL-FB is selected by SW13. In this case, the selector 21 outputs the second transmission signal (the transmission signal output from the baseband processing unit 60 and before being input to the multiplication unit 31) to the error extraction processing unit 232. The second transmission signal is output from the demodulation unit 22 to the error extraction processing unit 232. The second transmission signal from the demodulator 22 is fed back from the BPF 4 via the phase shifter 5A, antenna 6A, directional coupler 7A, SW8, SW12, feedback path ACAL-FB, SW13, ADC 14, and demodulator 22. It is a transmission signal. The SW 36 selects the one-dimensional ACAL LUT 34.

  The error extraction processing unit 232 receives the second transmission signal from the selector 21 and receives the second transmission signal from the demodulation unit 22. The error extraction processing unit 232 extracts an error between the second transmission signal from the selector 21 and the second transmission signal from the demodulation unit 22 as an output error of the antenna 6A. The LMS arithmetic processing unit 231 uses the LMS arithmetic processing so that the relative phase difference between the transmission signal output from the antenna 6A of the branch # 1 and the transmission signal output from the antenna 6A of the branch # 1 becomes a desired relative phase difference. A one-dimensional ACAL correction coefficient is calculated. The LMS arithmetic processing unit 231 updates the one-dimensional ACAL LUT 34 by storing the one-dimensional ACAL correction coefficient in the one-dimensional ACAL LUT 34 via the SW 24 and SW 36. The multiplication unit 31 multiplies the one-dimensional ACAL correction coefficient stored in the one-dimensional ACAL LUT 34 and the transmission signal so that the relative phase difference between the antenna 6A of the branch # 0 and the antenna 6A of the branch # 1 is desired. The relative phase difference is corrected.

  Next, ACAL in the two-dimensional direction is executed for the second branch (branch # 1) (steps S5 to S7).

  Next, the baseband processing unit 60 adds 1 to the constant N (step S8). Here, it is assumed that N exceeds 8 (step S9: Yes). That is, DPD, one-dimensional ACAL, and two-dimensional ACAL are executed for branch # 7. In this case, step S1 is executed.

[Effect of Example]
As described above, the base station apparatus 100 according to the present embodiment includes the plurality of branches # 0 to # 7 and the first switch (SW12). The plurality of branches # 0 to # 7 include a plurality of phase shifters 5A to 5D that adjust the phase of the transmission signal output from the filter (BPF4) at the subsequent stage of the power amplifier (PA2). The plurality of branches # 0 to # 7 transmit the transmission signals whose phases are adjusted by the plurality of phase shifters 5A to 5D from the plurality of antennas 6A to 6D, respectively. The SW 12 feeds back from each of the plurality of branches # 0 to # 7 when correcting the relative phase difference between the antennas (in this case, between the antennas 6A) in the one-dimensional direction (the horizontal direction X in FIGS. 1 and 2). Switch the transmitted signal. Each of the plurality of branches # 0 to # 7 has a second switch (SW8). SW8 is used to correct the relative phase difference between the antennas (in this case, between the antenna 6A and the antennas 6B to 6D) in the two-dimensional direction (vertical direction Y in FIGS. 1 and 2). The transmission signal fed back from each of 6D is switched.

  Thus, in the base station apparatus 100 of the present embodiment, the output feedback of each of the plurality of branches # 0 to # 7 is switched by the SW 12 when correcting the phase difference between the antennas in the one-dimensional direction. In each of the plurality of branches # 0 to # 7, when correcting the phase difference between the antennas in the two-dimensional direction, the output feedback of the plurality of antennas 6A to 6D is used as the output of the plurality of phase shifters 5A to 5D. It is switched by. Here, in the conventional base station apparatus (see FIG. 11), for example, when eight branches 1040 are provided and four antennas are provided in each branch 1040, the number of antennas is 32 in total. 32 signal lines for feedback signals for ACAL are also prepared. Thus, in the conventional base station apparatus, since the same number of signal lines as the number of antennas are provided, the circuit scale increases. On the other hand, in the base station apparatus 100 according to the embodiment, for example, when eight branches 40 are provided and each branch 40 is provided with four antennas, by providing SW8 in each branch 40, the feedback signal for ACAL is provided. One signal line may be provided. That is, in the base station apparatus 100 according to the embodiment, since it is only necessary to provide the same number of signal lines as the number of branches 40, an increase in circuit scale can be suppressed.

  Furthermore, in the base station apparatus 100 of the present embodiment, a plurality of phase shifters 5A to 5D are provided in each of the plurality of branches # 0 to # 7. Here, in the conventional base station apparatus (see FIG. 11), for example, when eight branches 1040 are provided and four antennas are provided in each branch 1040, the number of antennas is 32 in total. A total of 32 DACs, PAs, couplers, and BPFs are prepared. As described above, in the conventional base station apparatus, the same number of DACs, PAs, couplers, and BPFs as antennas are provided, so that the circuit scale increases. On the other hand, in the base station apparatus 100 according to the embodiment, for example, when eight branches 40 are provided and each branch 40 is provided with four antennas, by providing four phase shifters in each branch 40, DAC, PA A total of eight couplers and BPFs may be provided. That is, in the base station apparatus 100 according to the embodiment, it is only necessary to provide the same number of DACs, PAs, couplers, and BPFs as the number of branches 40, so that an increase in circuit scale can be suppressed.

  Further, in the base station apparatus 100 of the present embodiment, each of the plurality of branches # 0 to # 7 further includes first and second processing units (digital processing unit 20), and the digital processing unit 20 includes 1 Dimensional ACAL and 2-dimensional ACAL are performed. In the one-dimensional ACAL, the relative relationship between the antenna 6A of the first branch (branch # 0) among the plurality of branches # 0 to # 7 and the antenna 6A of the branches # 1 to # 7 other than the branch # 0. The phase difference is corrected to a desired relative phase difference. This correction is an error between a transmission signal fed back from the first antenna (antenna 6A) of the plurality of antennas 6A to 6D via SW8 and SW12 and an input signal before being input to PA2. This is performed based on an error (an output error of the antenna 6A). In the two-dimensional ACAL, the relative phase difference between the antenna 6A and the antennas 6B to 6D other than the antenna 6A is corrected to a desired relative phase difference. This correction is based on the output error of the antenna 6A and the second error (the output error of the antennas 6B to 6D) which is an error between the input signal and the transmission signal fed back from the antennas 6B to 6D other than the antenna 6A via SW8 and SW12. ).

  Thus, in the base station apparatus 100 of the present embodiment, the transmission signal is extracted from the antenna end as a feedback signal for ACAL. Here, in the case of high power handled by the macro cell, the transmission signals output from the phase shifters 5A to 5D may be distorted by the directional couplers 7A to 7D. On the other hand, in the case of power handled by a small cell, the transmission signals output from the phase shifters 5A to 5D can be extracted as ACAL feedback signals without being distorted by the directional couplers 7A to 7D. In the conventional base station apparatus, transmission signals are taken out as feedback signals for ACAL from couplers 1003A to 1003D provided before 1006A to 1006D (see FIG. 11). In this case, since the configuration (BPF 1004A to 1004D) from the couplers 1003A to 1003D to the antenna ends (end portions of 1006A to 1006D) is not considered, ACAL cannot be performed with high accuracy. On the other hand, in the base station apparatus 100 according to the embodiment, since the transmission signal is extracted from the antenna end as a feedback signal for ACAL, ACAL can be performed with high accuracy.

  Moreover, the base station apparatus 100 of a present Example further has the 3rd switch (SW11) which switches the signal fed back from the output of PA2 of each of the multiple branches # 0 to # 7. Each of the plurality of branches # 0 to # 7 further includes a third processing unit (digital processing unit 20), and the digital processing unit 20 executes DPD. In DPD, distortion characteristics due to PA2 are corrected based on a third error (an output error of PA2) that is an error between a signal fed back from the output of PA2 via SW11 and an input signal.

  As described above, in the base station apparatus 100 according to the present embodiment, DPD and ACAL are executed by one digital processing unit 20, so that an increase in circuit scale can be suppressed.

  The base station apparatus 100 of the present embodiment further includes a fourth switch (SW13), and the SW13 includes a first feedback path (feedback path DPD-FB) and a second feedback path (feedback path ACAL). -FB). The feedback path DPD-FB is a path for feeding back the output of PA2 via SW11. The feedback path ACAL-FB is a path for feeding back a transmission signal output from each of the plurality of antennas 6A to 6D via SW8 and SW12. Here, when the feedback path is switched to the feedback path DPD-FB, the digital processing unit 20 executes DPD. When the feedback path is switched to the feedback path ACAL-FB, the digital processing unit 20 executes ACAL in the one-dimensional direction and executes ACAL in the two-dimensional direction.

  As described above, in the base station apparatus 100 according to the present embodiment, the feedback path DPD-FB and ACAL-FB are switched to time division, so that the distortion characteristics due to PA2 are corrected by DPD, and then the one-dimensional ACAL, 2 Dimensional ACAL can be performed. In the base station apparatus 100 according to the present embodiment, the ACAL in the one-dimensional direction is executed and then the ACAL in the two-dimensional direction is executed. ACAL may be performed.

[Other embodiments]
Each component of each part illustrated in the embodiments does not necessarily need to be physically configured as illustrated. In other words, the specific form of distribution / integration of each part is not limited to the one shown in the figure, and all or a part thereof may be functionally or physically distributed / integrated in arbitrary units according to various loads and usage conditions. Can be configured.

  Furthermore, various processes performed by each device are executed entirely or arbitrarily on a CPU (Central Processing Unit) (or a microcomputer such as an MPU (Micro Processing Unit) or MCU (Micro Controller Unit)). You may make it do. Various processes may be executed in whole or in any part on a program that is analyzed and executed by a CPU (or a microcomputer such as an MPU or MCU) or hardware based on wired logic.

  The base station apparatus according to the embodiment can be realized by the following hardware configuration, for example.

  FIG. 9 is a diagram illustrating an example of a hardware configuration of the base station apparatus. As illustrated in FIG. 9, the base station apparatus 200 includes a processor 201, a memory 202, and an analog circuit 203. Examples of the processor 201 include a CPU, a DSP (Digital Signal Processor), and an FPGA (Field Programmable Gate Array). Examples of the memory 202 include a RAM (Random Access Memory) such as SDRAM (Synchronous Dynamic Random Access Memory), a ROM (Read Only Memory), a flash memory, and the like.

  Various processes performed in the base station apparatus 100 according to the embodiment may be realized by executing a program stored in various memories such as a nonvolatile storage medium using a processor. That is, a program corresponding to each process executed by the baseband processing unit 60 and the digital processing unit 20 may be recorded in the memory 202 and each program may be executed by the processor 201. The analog processing unit 10 is realized by the analog circuit 203.

  In addition, although the various processes performed with the base station apparatus 100 of an Example shall be performed by the processor 201 here, it is not limited to this, You may perform by several processors.

1 Digital-to-analog converter (DAC)
2 Power amplifier (PA)
3 Coupler 4 Band pass filter (BPF)
5A to 5D Phaser 6A to 6D Antenna 7A to 7D Directional coupler 8 Switch (SW)
10 Analog processing section 11 Switch (SW)
12 Switch (SW)
13 Switch (SW)
14 Analog-to-digital converter (ADC)
20 Digital Processing Unit 21 Selector 22 Demodulation Unit 23 Operation Unit (Operation Circuit)
24 switch (SW)
30 Correction Unit 31 Multiplication Unit 32 Multiplication Unit 33 DPD Look-up Table (DPD LUT)
34 One-dimensional ACAL lookup table (one-dimensional ACAL LUT)
35 2D ACAL control unit 36 Switch (SW)
40 Transmitter (branch)
51 Hybrid coupler 52 Switch (SW)
53 Switch (SW)
54A to 54D capacitors 55A to 55D capacitors 60 baseband signal processing unit 100 base station apparatus 200 base station apparatus 201 processor 202 memory 203 analog circuit 231 LMS arithmetic processing unit 232 error extraction processing unit

Claims (5)

A plurality of phase shifters for adjusting the phase of the transmission signal output from the filter at the subsequent stage of the power amplifier, and a plurality of branches for transmitting the transmission signals adjusted in phase by the plurality of phase shifters from the plurality of antennas, respectively;
A first switch that switches a transmission signal fed back from each of the plurality of branches when correcting a relative phase difference between antennas in a one-dimensional direction;
Have
Each of the plurality of branches is
A second switch for switching a transmission signal fed back from each of the plurality of antennas when correcting a relative phase difference between antennas in a two-dimensional direction;
A base station apparatus comprising: Each of the plurality of branches is
A first difference between a transmission signal fed back from the first antenna of the plurality of antennas via the second switch and the first switch and an input signal before being input to the power amplifier. Based on the error, a relative phase difference between the first antenna of the first branch of the plurality of branches and the first antenna of a branch other than the first branch is determined as a desired relative phase difference. A first processing unit that executes ACAL (Antenna Calibration) in a one-dimensional direction to correct to
Based on the first error and a second error that is an error between the input signal and the transmission signal fed back from the antenna other than the first antenna through the second switch and the first switch. A second processing unit that performs ACAL in a two-dimensional direction for correcting a relative phase difference between the first antenna and an antenna other than the first antenna to a desired relative phase difference;
The base station apparatus further comprising: A third switch for switching a signal fed back from the output of the power amplifier of each of the plurality of branches;
Further comprising
Each of the plurality of branches is
DPD (Digital Pre-Distortion) that corrects distortion characteristics of the power amplifier based on a third error that is an error between a signal fed back from the output of the power amplifier via the third switch and the input signal A third processing unit for executing
The base station apparatus according to claim 2, further comprising: A first feedback path for feeding back the output of the power amplifier via the third switch; and a transmission signal output from each of the plurality of antennas via the second switch and the first switch. A fourth switch for switching between and a second feedback path for feedback via
Further comprising
When the feedback path is switched to the first feedback path, the third processing unit executes the DPD,
When the feedback path is switched to the second feedback path, the first processing unit executes the one-dimensional direction ACAL, and the second processing unit executes the two-dimensional direction ACAL.
The base station apparatus according to claim 3. Base station equipment
The plurality of branches adjust the phase of the transmission signal output from the filter subsequent to the power amplifier, and transmit the phase-adjusted transmission signal from the plurality of antennas.
When correcting the relative phase difference between the antennas in a one-dimensional direction, the transmission signal fed back from each of the plurality of branches is switched,
In each of the plurality of branches, when correcting a relative phase difference between antennas in a two-dimensional direction, a transmission signal fed back from each of the plurality of antennas is switched.
An antenna control method characterized by executing processing.

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