JP2012039560A - Wireless base station apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wireless base station apparatus where it is not necessary to use a device of high specification, and where a product cost is reduced.SOLUTION: An output of a mixer 117 is given to a selection switch 103, and it is selected, by the selection switch 103, whether to be given to a selection switch 105 of a latter stage as it is via a signal wiring SC, or given to the selection switch 105 after filtering via a filter part 104. A terminal A of the selection switch 105 is connected to a terminal A of the selection switch 103 via the signal wiring SC, and a terminal B of the selection switch 105 is connected to an output of the filter part 104. The selection switch 105 is switched so as to select the terminal A in the case where the output of the selection switch 103 is given to an amplifier 106 as it is, and is switched so as to select the terminal B in the case where the output filtered through the filter part 104 is given to the amplifier 106.

Description

  The present invention relates to a radio base station apparatus, and more particularly to a radio base station apparatus that performs communication in a TDD (Time Division Duplexing) scheme.

  In the radio base station apparatus, for example, as disclosed in Patent Document 1, in order to correct distortion of the transmission signal amplified by the power amplifying unit, digital processing called DPD (Digital Pre-Distortion) is used. Distortion correction processing has been proposed.

JP 2005-151119 A

  The above-described Patent Document 1 exemplifies a configuration of a wireless transmitter, but recently, a configuration in which a common circuit (shared circuit) is used in a feedback circuit for DPD and a receiving circuit in a wireless base station device is proposed. Has been.

  Here, with reference to FIG. 8, the necessary passbands for the DPD feedback circuit and the receiving circuit will be described.

  FIG. 8 is a diagram conceptually showing a spectrum waveform of a transmission signal in the TDD system, where the horizontal axis indicates the frequency and the vertical axis indicates the signal level. In FIG. 8, the spectrum waveform WV has a mountain shape that protrudes at the center and has a flat top, and the mountain skirt portion is gently inclined. In such a spectrum waveform WV, the width A of the protruding portion at the center corresponds to the band of the received signal, and the entire width B of the spectrum waveform WV including the peak portion corresponds to the band necessary for distortion correction. Therefore, the band corresponding to the width C and the width D corresponding to the crest portion is not necessary for the received signal, but is necessary for distortion correction.

  As described above, the required bandwidth differs greatly between the feedback circuit for DPD and the receiving circuit, but so far, an amplifier or the like is used so as not to distort even an interference wave having a high signal level according to the band used in DPD. In addition, it is necessary to use a high-spec device, resulting in an increase in product cost.

  The present invention was made to solve the above problems, and it is not necessary to use a high-spec device in a radio base station apparatus having a shared circuit for a feedback circuit and a receiving circuit for DPD, An object of the present invention is to provide a radio base station apparatus with reduced product cost.

  In order to solve the above-described problem, a radio base station apparatus according to the present invention receives an amplification unit that amplifies a transmission signal transmitted to a communication terminal and an amplified transmission signal that is output from the amplification unit, and performs distortion correction. A distortion correction unit, a reception data acquisition unit that acquires a reception signal from the communication terminal, and when performing the distortion correction when transmitting, the amplified transmission signal is provided to the distortion correction unit and received. A switching circuit that switches a signal path so as to give the received signal to the received data acquisition unit, and the switching circuit is a first signal in which a filter unit that passes only a predetermined band is inserted. A path, a second signal path that does not have the filter unit, and the transmission signal after amplification passes through the second signal path when receiving the distortion correction when transmitting. In the case Signal has and a path selection means for performing routing so as to pass through the first signal path.

  With the radio base station apparatus according to the present invention, a radio base station apparatus with reduced product cost can be obtained.

It is a block diagram which shows the structure of the radio base station apparatus of embodiment which concerns on this invention. It is a flowchart explaining the transmission operation | movement and reception operation | movement in the radio base station apparatus of embodiment which concerns on this invention. It is a figure which shows the switching control of a selection switch in the radio base station apparatus of embodiment which concerns on this invention. It is a time chart explaining an example of transmission operation | movement and reception operation | movement in the radio base station apparatus of embodiment which concerns on this invention. It is a figure which shows a spectrum waveform when not performing distortion correction, when performing distortion correction. It is a figure which shows the smoothed spectrum waveform when not performing distortion correction, when performing distortion correction. It is a block diagram which shows the structure of the modification of the radio base station apparatus of embodiment which concerns on this invention. It is a figure which shows typically a required pass band with the feedback circuit and receiving circuit for DPD, respectively.

<Embodiment>
<Device configuration>
FIG. 1 is a block diagram showing a configuration of a radio base station apparatus 100 according to an embodiment of the present invention. The communication device 100 according to the present embodiment performs, for example, two-way wireless communication with a communication partner device using the TDD method, and includes a wireless communication unit 1, a D / A converter 2, an A / D converter 3, and a digital processing unit. 4 is provided.

  The wireless communication unit 1 converts the received signal in the carrier band received by the antenna 10 into a received signal in the base band, and outputs the received signal in the base band. The wireless communication unit 1 converts the baseband transmission signal output from the D / A converter 2 into a transmission signal in the carrier band, and wirelessly transmits the transmission signal in the carrier band from the antenna 10.

  The D / A converter 2 converts the transmission signal output from the digital processing unit 4 from a digital method to an analog method and outputs the converted signal. The A / D converter 3 converts the reception signal output from the wireless communication unit 1 from an analog system to a digital system and outputs the converted signal.

  The digital processing unit 4 generates a digital transmission signal including bit data for transmission, and inputs the transmission signal to the D / A converter 2. The digital processing unit 4 acquires bit data included in the reception signal output from the A / D converter 3.

  The configuration of radio base station apparatus 100 will be described in more detail. Radio communication section 1 includes antenna 10, mixer 101 that receives the output of D / A converter 2, amplifier 102 that receives the output of mixer 101, and the output of amplifier 102. A mixer 111 for receiving, an amplifier 112 for receiving the output of the mixer 111, a branch coupler 113 for receiving the output of the amplifier 112, and a selection switch 114 for receiving the output of the branch coupler 113 are provided. Further, the wireless communication unit 1 includes an amplifier 115 that receives the output of the selection switch 114, a selection switch 116 that receives the output of the amplifier 115, a mixer 117 that receives the output of the selection switch 116, a selection switch 103 that receives the output of the mixer 117, and a selection switch. A filter unit 104 that receives one output of 103, a selection switch 105 that receives the other output of the selection switch 103 at one input and an output of the filter unit 104 at the other input, an amplifier 106 that receives the output of the selection switch 105, and A mixer 107 that receives the output of the amplifier 106 is provided. The wireless communication unit 1 also includes a local oscillator 108 that supplies an output signal for multiplication to the mixers 101 and 107 and a local oscillator 118 that supplies an output signal for multiplication to the mixers 111 and 117.

  The mixer 101 multiplies the transmission signal output from the D / A converter 2 and the output signal of the local oscillator 108. The amplifier 102 amplifies the transmission signal output from the mixer 101 and outputs it. In this example, in order to gradually increase the transmission frequency, a mixer 111 is provided after the amplifier 102, and the amplified transmission signal output from the amplifier 102 is multiplied by the output signal of the local oscillator 118. As a result, the transmission signal is up-converted to obtain a transmission signal in the carrier band.

  The transmission signal in the carrier band output from the mixer 111 is amplified by the amplifier 112, the transmission signal amplified by the amplification unit 12 is branched into two by the branch coupler 113, and one transmission signal is given to the selection switch 114. The other transmission signal is supplied to the selection switch 116.

  The selection switch 114 is a switch that selects whether the transmission signal output from the branch coupler 113 is transmitted from the antenna 10 or the reception signal received by the antenna 10 is input to the amplifier 115, and is output from the branch coupler 113. The transmission signal is input to the terminal A, and the reception signal received by the antenna 10 is output via the terminal B. Accordingly, the selection switch 114 is switched to select the terminal A when transmitting the transmission signal output from the branch coupler 113 from the antenna 10, and when outputting the reception signal received by the antenna 10, It is switched to select terminal B. Note that the switching operation of the selection switch 114 is controlled by the digital processing unit 4.

  The amplifier 115 amplifies the received reception signal and outputs it. The selection switch 116 is a switch for selecting whether to output the transmission signal output from the branch coupler 113 or to output the reception signal output from the amplifier 115. The transmission signal output from the branch coupler 113 is the terminal A. The reception signal output from the selection switch 114 is input to the terminal B. Therefore, the selection switch 116 is switched to select the terminal A when outputting the transmission signal output from the branch coupler 113, and selects the terminal B when outputting the reception signal output from the amplifier 115. To be switched. Note that the switching operation by the selection switch 116 is controlled by the digital processing unit 4.

  The mixer 117 multiplies the output signal of the selection switch 116 and the output signal of the local oscillator 118. In this example, in order to gradually lower the reception frequency, a mixer 107 is provided immediately before the A / D converter 3 to multiply the amplified transmission signal output from the amplifier 106 and the output signal of the local oscillator 108. . As a result, the received signal is down-converted and output from the mixer 107.

  Whether the output of the mixer 117 is given to the selection switch 103, is it given to the selection switch 105 in the subsequent stage via the signal wiring SC by the selection switch 103, or is it filtered to the selection switch 105 via the filter unit 104? Is selected. That is, the A terminal of the selection switch 103 is connected to the A terminal of the selection switch 105, and the B terminal of the selection switch 103 is connected to the input of the filter unit 104. Therefore, the selection switch 103 is switched to select the terminal A when the output of the mixer 117 is supplied to the selection switch 105, and the terminal B is selected when the output of the mixer 117 is supplied to the filter unit 104. Can be switched. Note that the switching operation of the selection switch 103 is controlled by the digital processing unit 4.

  The filter unit 104 is configured by a so-called band-pass filter, and is configured such that only the band of the received signal corresponding to the protruding portion having the width A at the center portion passes through the spectrum waveform WV shown in FIG.

  The selection switch 105 selects whether the output of the selection switch 103 is directly supplied to the amplifier 106 or whether the output filtered through the filter unit 104 is supplied to the amplifier 106. That is, the A terminal of the selection switch 105 is connected to the A terminal of the selection switch 103 via the signal wiring SC, and the B terminal of the selection switch 105 is connected to the output of the filter unit 104. Therefore, the selection switch 105 is switched so as to select the terminal A when the output of the selection switch 103 is directly supplied to the amplifier 106, and when the output filtered through the filter unit 104 is supplied to the amplifier 106, the terminal B is selected. Can be switched to select. Note that the switching operation of the selection switch 105 is controlled by the digital processing unit 4.

  Here, a signal path that gives the output of the mixer 117 to the selection switch 105 via the filter unit 104 is referred to as a first signal path, and a signal path that gives the output of the mixer 117 to the selection switch 105 as it is via the signal wiring SC. Is referred to as a second signal path.

  The selection switch 103, the signal wiring SC, the filter unit 104, and the selection switch 105 are circuits that switch signals to be fed to the DPD feedback circuit and the reception circuit by switching signal paths, and are therefore referred to as switching circuits. The switches 103 and 105 are called route selection means because they perform route selection between the first signal route and the second signal route.

  The A / D converter 3 converts the output signal of the mixer 107 from an analog format to a digital format. When the selection switch 116 outputs a reception signal received by the antenna 10, that is, when a circuit from the selection switch 116 to the selection switch 105 is used as a reception circuit, the A / D converter 3 receives the reception signal. Are down-converted and input. On the other hand, when the selection switch 116 outputs a transmission signal from the branch coupler 13, that is, when the circuit from the selection switch 116 to the selection switch 105 is used as a feedback circuit for DPD, the A / D converter 3 The output signal of the amplifier 112 fed back from the transmission system circuit to the reception system circuit is down-converted and input.

  The digital processing unit 4 is configured by a CPU, a memory, and the like. As a functional block, a transmission signal generation unit 40, a reception data acquisition unit 41, delay units 42 and 45, a distortion correction unit 43, an amplitude calculation unit 44, an error correction A unit 46, a quadrature modulation unit 47, a quadrature detection unit 48, and a selection switch 49.

  The transmission signal generation unit 40 generates and outputs a digital transmission signal SS including bit data for transmission. The transmission signal SS generated by the transmission signal generation unit 40 is a complex signal and includes an I (Inphase) component and a Q (Quadrature) component.

  The amplitude calculator 44 calculates the amplitude of the transmission signal SS output from the transmission signal generator 40. Specifically, the amplitude calculation unit 44 adds the value obtained by squaring the I component of the transmission signal SS and the value obtained by squaring the Q component of the transmission signal SS, and 1 of the value obtained thereby. Let / square be the amplitude of the transmission signal SS. Then, the amplitude calculation unit 44 outputs the obtained amplitude to the distortion correction unit 43.

  The delay unit 42 delays and outputs the transmission signal SS output from the transmission signal generation unit 40. The distortion correction unit 43 stores a distortion correction value table 430 in which distortion correction values for correcting distortion of the transmission signal amplified by the amplifier 112 are registered. The distortion correction unit 43 corrects the transmission signal SS by adjusting the amplitude and phase of the transmission signal SS output from the delay unit 42 based on the distortion correction value table 430. The orthogonal modulation unit 47 performs orthogonal modulation on the transmission signal SS corrected by the distortion correction unit 43, converts the transmission signal SS into a real signal, and outputs the real signal.

  The distortion correction value table 430 is a look-up table (LUT), and the amplitude of the transmission signal SS and the distortion correction value are associated one to one. The distortion correction value is represented by a complex number.

  When the distortion correction unit 43 receives the amplitude of the transmission signal SS from the amplitude calculation unit 44, the distortion correction unit 43 refers to the distortion correction value table 430 and acquires a distortion correction value corresponding to the amplitude. The distortion correction unit 43 corrects the amplitude and phase of the transmission signal SS by performing complex multiplication on the acquired distortion correction value and the transmission signal SS input from the delay unit 42.

  The amount of delay with respect to the transmission signal SS in the delay unit 42 is determined by the distortion correction unit 43, after the transmission signal SS is input to the amplitude calculation unit 44, the distortion correction value corresponding to the amplitude of the transmission signal SS. It is set to coincide with the time from 430 to acquisition.

  Therefore, the distortion correction unit 43 adjusts the amplitude and phase of the input transmission signal SS based on the distortion correction value associated with the amplitude. Thereby, the distortion of the transmission signal output from the amplifier 112 is corrected.

  The quadrature detection unit 48 performs quadrature detection on the output signal from the A / D converter 3, converts the output signal from a real signal to a complex signal, and outputs the converted signal. When the selection switch 116 outputs the output signal from the branch coupler 113, the quadrature detection unit 48 acquires the transmission signal SS fed back to the digital processing unit 4, and the transmission signal SS is sent from the quadrature detection unit 48. Is output. On the other hand, when the selection switch 116 outputs the reception signal from the amplifier 15, the quadrature detection unit 48 converts the reception signal into a complex signal, and the reception signal of the complex signal is output from the quadrature detection unit 48. . The output of the quadrature detection unit 48 is given to the selection switch 49, and the selection switch 49 controls whether it is given to the error correction unit 46 or the reception data acquisition unit 41. That is, the A terminal of the selection switch 49 is connected to the error correction unit 46, and the B terminal of the selection switch 49 is connected to the reception data acquisition unit 41. Therefore, the selection switch 49 is switched to select the terminal A when the output of the quadrature detection unit 48 is given to the error correction unit 46, and is selected to select the terminal B when given to the reception data acquisition unit 41. Can be switched. The switching operation by the selection switch 49 is controlled by the digital processing unit 4.

  The reception data acquisition unit 41 performs demodulation processing on the reception signal output from the quadrature detection unit 48 and acquires bit data included in the reception signal.

  The delay unit 45 delays and outputs the transmission signal SS output from the transmission signal generation unit 40. The error correction unit 46 corrects the error of the feedback transmission signal from the quadrature detection unit 48 with respect to the transmission signal SS from the delay unit 45.

  In the present invention, the configuration of the distortion correction unit 43 is not limited, and the configuration of the distortion correction unit 43 shown in FIG. 1 is merely an example, and any distortion correction circuit may be employed as long as DPD can be realized. Also good.

<Operation>
Next, a transmission operation and a reception operation in the radio base station apparatus 100 will be described using the flowchart shown in FIG. 2 with reference to FIG.

<Transmission operation>
In the TDD scheme, since the reception period and the transmission period are alternately repeated, when the radio base station apparatus 100 starts operating, first, in step S1, it is determined whether it is a reception period or a transmission period. If it is determined in step S1 that it is not a reception period, that is, a transmission period, transmission processing is started (step S2).

  In the transmission process, as described above, first, the transmission signal generation unit 40 starts by generating a digital transmission signal SS including bit data for transmission. However, the transmission process is related to the invention. Since it is thin, further explanation is omitted.

  After starting the transmission process, it is confirmed whether skipping to step S5 (the meaning of this skip operation will be described later) is set (step S3). If skipping is set, the process proceeds to step S5. Otherwise, it is determined whether or not a predetermined condition that is assumed to cause a change in the distortion correction value in the distortion correction value table 430 that is an LUT is satisfied (step S4). Such a determination is made by a control unit (not shown) of the digital processing unit 4 constituted by a CPU or the like.

  Here, for example, the predetermined condition refers to a condition in which the operational characteristics of the amplifier change due to a difference in temperature such as morning and night in the time zone of a day, and when a predetermined time is reached. Determines that the predetermined condition of step S4 is satisfied. In addition, the temperature is monitored in the radio base station apparatus 100, and when the temperature in the apparatus exceeds a predetermined temperature, it is determined that the predetermined condition in step S4 is satisfied. Or may be determined under other conditions. In short, there is no particular limitation as long as it can be a condition for determining whether or not to perform distortion correction by DPD.

  If it is determined in step S4 that the predetermined condition is satisfied, the process proceeds to step S5, and if not, the transmission process is continued.

  In step S5, the transmission signal given from the D / A converter 2 to the selection switch 116 via the mixer 101, the amplifier 102, the mixer 111, the amplifier 112, and the branch coupler 113 is sent to the selection switch 103 via the mixer 117. The switch operation is performed by the selection switch 103 so that the selection switch 103 is provided as it is. Step S5 can be referred to as a step of selecting the second signal path.

  Note that the signal passing through the second signal path is a signal in a band corresponding to the width B in the spectrum waveform WV shown in FIG. 8, and includes a band corresponding to the width C and the width D necessary for distortion correction. It is out.

  The output of the mixer 117 supplied to the selection switch 105 is supplied to the amplifier 106 via the selection switch 105, and the amplified transmission signal output from the amplifier 106 is multiplied by the output signal of the local oscillator 108 in the mixer 107. And supplied to the A / D converter 3.

  The output signal from the A / D converter 3 is given to the quadrature detection unit 48, and after quadrature detection is executed, it is given to the error correction unit 46 via the selection switch 49, and the error of the transmission signal is corrected.

  Further, the distortion correction unit 43 estimates the distortion of the transmission signal amplified by the amplifier 112 based on the transmission signal corrected by the error correction unit 46 and the transmission signal SS from the delay unit 45. That is, the distortion correction unit 43 estimates the distortion of the transmission signal amplified by the amplifier 112 based on the transmission signal before being amplified by the amplifier 112 and the transmission signal after being amplified by the amplifier 112. . Then, the distortion correction unit 43 updates the above-described distortion correction value table 430 (LUT) based on the estimation result (step S6). Thereafter, the distortion correction unit 43 corrects the transmission signal SS from the delay unit 42 using the updated distortion correction value table 430.

  After the distortion correction value table 430 is updated, the transmission signal SS is corrected using the updated distortion correction value table 430, and the transmission of the corrected transmission signal SS is completed (step S7), step In S8, it is determined whether or not the change of the distortion correction value constituting the distortion correction value table 430 has converged.

  That is, when the distortion of the transmission signal SS is corrected by performing distortion correction by DPD by feeding back the transmission signal SS to the distortion correction unit 43, the characteristics of the amplifier 112 and the like further change. It becomes necessary to change the distortion correction values constituting the distortion correction value table 430 again. In such a case, it is determined that the change in the distortion correction value has not converged, and the feedback of the transmission signal SS for DPD is executed also in the next transmission slot. In the next transmission slot, the steps from step S3 to step S3 are performed. It is set to skip to S5 (step S9).

  Such a skip operation is an operation provided for performing DPD monitoring regardless of whether or not the predetermined condition in step S4 is satisfied, and the effect of shortening the processing time by omitting the determination operation in step S4. There is also.

  After step S9, it waits for the timing to send the next transmission slot (step S10), and when the timing to send the next transmission slot is reached, the operation from step S3 is repeated.

  On the other hand, if it is determined in step S8 that the change in distortion correction value has converged, the operations in step S1 and subsequent steps are repeated for the next transmission slot and reception slot.

<Receive operation>
If it is determined in step S 1 that it is the reception period, the selection switches 114 and 116 are configured so that the reception signal received by the antenna 10 is input to the amplifier 115 and the reception signal output from the amplifier 115 is supplied to the mixer 117. In addition, the switch operation is performed to switch the selection switches 103 and 105 so that the output of the mixer 117 is given to the amplifier 106 via the selection switch 103, the filter unit 104, and the selection switch 105 (step S11). Here, step S11 can be referred to as a step of selecting the first signal path.

  By passing the received signal through the filter unit 104, only the band of the width A corresponding to the band of the received signal in the spectrum waveform WV shown in FIG. The band corresponding to the width D is cut.

  The received signal is supplied to the A / D converter 3 through the filter unit 104, the selection switch 105, the amplifier 106, and the mixer 107 by the switch operation in step S11, and is converted into a digital signal by the A / D converter 3 to be orthogonal. By being supplied to the detection unit 48, the reception signal is converted into a complex signal, and the reception signal of the complex signal is output from the quadrature detection unit 48. In this case, the output of the quadrature detection unit 48 is given to the reception data acquisition unit 41 by the selection switch 49, and the reception data acquisition unit 41 performs reception processing such as demodulation processing on the reception signal output from the quadrature detection unit 48. Start (step S12).

  If it is determined in step S13 that the reception process has been completed, the operations in and after step S1 are repeated for the next transmission slot and reception slot.

  In the transmission operation and reception operation of the radio base station apparatus 100 described above, the switching control of the selection switch is collectively shown in FIG.

  In FIG. 3, transmission 1 is performed when transmission signal feedback (referred to as DPD monitor) for DPD is performed, transmission 1 is performed when DPD monitor is not performed, and transmission is illustrated together with reception. Yes. For convenience, the selection switches 114, 116, 49, 103, and 105 are shown as SW1, SW2, SW3, SW4, and SW5, respectively.

  As shown in FIG. 3, in transmission 1 for performing DPD monitoring, control is performed so that all of SW1 to SW5 are switched to the terminal A. On the other hand, in transmission 2 in which DPD monitoring is not performed, that is, normal transmission, only SW1 is switched to terminal A, and SW2 to SW5 can be switched to either terminal A or terminal B. This is expressed as Don't Care (DC). That is, when DPD monitoring is not performed, the transmission signal output from the branch coupler 113 may be given to the antenna 10 via the selection switch 114 (SW1). For example, the transmission signal output from the branch coupler 113 is selected. This is because even if it is given to each component after the mixer 117 via the switch 116 (SW2), since the operation is stopped when the DPD monitor is not performed, no problem occurs.

  In the case of reception, DPD monitoring is not performed, and the selection switch 114 is switched so that the reception signal received by the antenna 10 is input to the amplifier 115, and the reception signal amplified by the amplifier 115 is supplied to the mixer 117. The selector switch 116 is switched to control the switches SW1, SW2, SW4, and SW5 to the terminal B so that the output of the mixer 117 passes through the first signal path. In the digital processing unit 4, the selection switch 49 (SW 3) is controlled to be switched to the terminal B so that the output of the quadrature detection unit 48 is given to the reception data acquisition unit 41.

  Next, an example of the transmission operation and the reception operation will be described using the time chart shown in FIG. In FIG. 4, for the sake of simplicity, it is assumed that each of the transmission period and the reception period is composed of one slot, and the terms of transmission 1, transmission 2, and reception described above are assigned to each slot. Yes.

  In FIG. 4, the reception slot (upstream) only receives every other reception slot, but in the transmission period (downstream), the transmission 2 slot that does not perform DPD monitoring is normally output. As described with reference to FIG. 2, when a predetermined condition that the distortion correction value in the distortion correction value table 430 (FIG. 1) as the LUT is assumed to change is satisfied (step S5), the DPD monitor Transmission 1 is performed.

  In this transmission 1, as described above, when the change of the distortion correction value does not converge in only one slot, DPD monitoring is performed in the next transmission slot (step S9), and in FIG. As an example, the case where the slot of transmission 1 continues three times is shown.

  When the distortion correction value change converges (step S8), the next transmission slot is transmission 2.

  In this way, when performing DPD monitoring, one transmission slot is set as a transmission 1 slot, and the transmission 1 slot is continuously output until the distortion correction value changes converge, thereby obtaining an appropriate distortion correction value. be able to.

  In FIG. 4, an example in which each of the transmission period and the reception period is configured by one slot is shown. However, each of the transmission period and the reception period may be configured by a plurality of slots. The length may be different.

  According to the radio base station apparatus 100 described above, when DPD monitoring is performed, the second signal path that does not pass through the filter unit 104 (FIG. 1) is selected and the transmission signal is fed back, so that FIG. As shown, the bands corresponding to the width C and the width D necessary for distortion correction are given to the distortion correction unit 43 via the error correction unit 46 without being cut, so that the distortion correction value is prevented from deteriorating. Is done. On the other hand, in the case of reception, the first signal path passing through the filter unit 104 is selected and the received signal is given to the digital processing unit 4, so that the received signal is included in the spectrum waveform WV as shown in FIG. Only the band with the width A corresponding to the band A passes through the filter unit 104, and the band corresponding to the width C and the width D unnecessary for the received signal is cut, so that the interference wave from the adjacent channel can be suppressed. It becomes possible. For this reason, an expensive device required to have a high level of linearity is used for the devices constituting the receiving circuit, for example, the amplifier 106 and the mixer 107 shown in FIG. Since it is not necessary, the apparatus cost can be reduced.

  Here, spectrum waveforms obtained respectively when distortion correction is performed, when distortion correction is not performed, and when distortion correction is performed based on a transmission signal in which bands corresponding to the width C and the width D are cut through the filter unit 104 are shown. As shown in FIG.

  In FIG. 5, the horizontal axis represents the frequency (MHz), the vertical axis represents the signal level (dBm), the spectrum waveform when distortion correction is performed is C1, and the spectrum waveform when distortion correction is not performed is C3. The spectrum waveform when distortion correction is performed based on the transmission signal that has passed through the filter unit 104 is shown as C2.

  As shown in FIG. 5, when the distortion correction is not performed and the distortion correction is compared, it can be seen that when the distortion correction is performed, the spurious component is reduced by about 10 dBm. Even when it is performed, it can be seen that when the distortion correction is performed based on the transmission signal that has passed through the filter unit 104, the spurious component is increased by several dBm. This is because the band necessary for distortion correction is cut from the transmission signal by passing through the filter unit 104, which means that the distortion correction value has deteriorated by several dBm.

  In the radio base station apparatus 100 according to the present invention, when distortion correction is performed, the second signal path that does not pass through the filter unit 104 (FIG. 1) can be selected, so that the distortion correction value is prevented from deteriorating. Therefore, it is possible to output a transmission signal with less spurious components.

  FIG. 6 is a diagram showing the waveform shown in FIG. 5 smoothed to highlight the difference between the spectrum waveforms C1 to C3, and it can be seen that there is a maximum difference of several dBm between the spectrum waveforms C1 and C2. Although much effort is required to lower the distortion correction value by several dBm by improving the DPD algorithm and improving the performance of the IC (integrated circuit), this can be achieved relatively easily according to the present invention. .

<Modification>
The radio base station apparatus 100 described with reference to FIG. 1 modulates the transmission signal by the orthogonal modulation unit 47 and then converts the digital signal from the analog method by the D / A converter 2 and converts the received signal to A / D conversion. The configuration in which the quadrature detection unit 48 detects after the conversion from the analog method to the digital method by the device 3 is adopted, but the configuration of the radio base station apparatus 100A shown in FIG. 7 may be adopted.

  In the radio base station apparatus 100A shown in FIG. 7, the D / A converter 2 converts the transmission signal output from the digital processing unit 4 from a digital method to an analog method, and then performs modulation in the orthogonal modulation unit 5 to perform modulation. A later transmission signal is input to the amplifier 102. The output of the amplifier 106 is detected by the quadrature detection unit 6, converted from an analog method to a digital method by the A / D converter 3, and supplied to the digital processing unit 4. In addition, the same code | symbol is attached | subjected about the structure same as the radio base station apparatus 100 shown in FIG. 1, and the overlapping description is abbreviate | omitted. In radio base station apparatus 100A, a mixer is not provided before amplifier 102 and after amplifier 106, but there is no difference from radio base station apparatus 100 in the basic operation.

  In the radio base station apparatus 100A having such a configuration, the linearity of the devices constituting the receiving circuit, for example, the amplifier 106 and the quadrature detection unit 6 shown in FIG. Since it is not necessary to use an expensive device required to a high level, the apparatus cost can be reduced.

49, 103, 105, 114, 116 Selection switch 104 Filter section

Claims (4)

A wireless base station device that communicates with a communication terminal wirelessly,
An amplifying unit for amplifying a transmission signal to be transmitted to the communication terminal;
A distortion correction unit that receives the amplified transmission signal output from the amplification unit and performs distortion correction;
A reception data acquisition unit for acquiring a reception signal from the communication terminal;
When transmitting, when the distortion correction is performed, the amplified transmission signal is given to the distortion correction unit, and when receiving, the signal path is set so as to give the received signal to the received data acquisition unit. A switching circuit for switching,
The switching circuit is
A first signal path in which a filter unit that passes only a predetermined band is inserted;
A second signal path not having the filter unit;
When performing the distortion correction when transmitting, the amplified transmission signal passes through the second signal path, and when receiving, the received signal passes through the first signal path. A radio base station apparatus comprising: path selection means for performing path selection. The filter unit is a bandpass filter,
The predetermined band is
The radio base station apparatus according to claim 1, wherein the radio base station apparatus corresponds to a band of the received signal. The route selection means includes
An input unit to which the amplified transmission signal and the reception signal are input as input signals; and two output units to which the input sides of the first and second signal paths are respectively connected; , A first selection switch for switching to the two output units and outputting,
Two input units to which the output sides of the first and second signal paths are respectively connected, and a second selection switch for switching the input signals input from the two input units to one output unit and outputting them Have
When performing the distortion correction when transmitting, the first and second selection switches are switched so that the amplified transmission signal passes through the second signal path,
The radio base station apparatus according to claim 1, wherein when receiving, the first and second selection switches are switched so that the received signal passes through the first signal path. The radio base station apparatus communicates with the communication terminal by a TDD (Time Division Duplexing) method,
The radio base station apparatus according to claim 1, wherein if the distortion correction value change does not converge as a result of the distortion correction, the distortion correction is performed also in the next transmission slot.