JP2012175655A - Signal processor, baseband processor, and wireless communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique by which a wireless communication device capable of controlling directivity of a plurality of antennas is easily obtained.SOLUTION: A signal processor 12 is connected to a plurality of wireless processors, each connected to an antenna, and a baseband processor. In the signal processor 12, a baseband signal generator 122 generates a baseband reception signal to which a CP is added, such that phase variation, which occurs in the reception signal by intentionally setting a DFT window so as to overlap with the CP in a DFT processor 120, is corrected.

Description

  The present invention relates to wireless communication technology.

  Conventionally, various techniques relating to wireless communication have been proposed. For example, Patent Document 1 discloses a technique related to a receiving apparatus that receives an OFDM (Orthogonal Frequency Division Multiplexing) signal.

JP 2007-110333 A

  A wireless communication device such as a base station or a communication terminal is often composed of a wireless processing device that processes a wireless signal received by an antenna and a baseband processing device that processes a baseband signal.

  On the other hand, in a wireless communication apparatus, an adaptive array antenna system that adaptively controls the directivity of an array antenna including a plurality of antennas may be employed.

  A wireless communication device that does not use the adaptive array antenna method and a wireless communication device that uses the adaptive array antenna method have different processing for baseband signals. It is difficult to realize a wireless communication apparatus adopting the adaptive array antenna system by using the baseband processing apparatus of the communication apparatus as it is.

  Accordingly, the present invention has been made in view of the above points, and provides a technique capable of easily realizing a wireless communication apparatus capable of controlling the directivity of a plurality of antennas. Objective.

  In order to solve the above-described problem, a signal processing apparatus according to the present invention uses a multi-carrier signal including a CP (cyclic prefix) superimposed on a plurality of subcarriers orthogonal to each other and received by an antenna as a baseband received signal. A signal processing device connected to a plurality of wireless processing devices that convert and output to a baseband processing device that processes a baseband received signal, and a baseband output from each of the plurality of wireless processing devices A Fourier transform processing unit that performs a Fourier transform process on each of the plurality of received signals, and a plurality of output signals corresponding to the plurality of received signals that are output from the Fourier transform processing unit. Multiple reception weights for controlling the reception directivity at multiple antennas connected to each wireless processing device A reception weight processing unit configured to generate a new reception signal by adding the plurality of output signals each having the plurality of reception weights set, and a reception signal generated by the reception weight processing unit. A baseband signal generation unit that performs an inverse Fourier transform process on the signal and generates and outputs a baseband reception signal to which a CP is added based on a signal obtained by the inverse Fourier transform process, and the baseband signal generation unit Is received by the baseband processing device, and the Fourier transform processing unit opens a Fourier transform window so that the received signal for one symbol is intentionally applied to the CP included therein. And the baseband signal generator is set so that a Fourier transform window is intentionally applied to the CP in the Fourier transform processor. Accordingly, as the phase changes occurring in the received signal is corrected to produce a baseband received signal which CP has been added.

  In one aspect of the signal processing apparatus according to the present invention, the baseband signal generation unit relates to a multicarrier signal obtained by performing inverse Fourier transform processing on the reception signal generated by the reception weight processing unit. The first part of the multi-carrier signal for one symbol is copied and added after the multi-carrier signal for one symbol, and the last part of the multi-carrier signal for one symbol is copied for the one symbol. By adding the signal before the multicarrier signal, a baseband reception signal to which CP is added is generated so that the phase change is corrected.

  In the aspect of the signal processing device according to the present invention, the baseband signal generation unit corrects the phase change by changing the phase of the reception signal generated by the reception weight processing unit, and By adding a CP to a signal obtained by performing an inverse Fourier transform process on the received signal, a baseband received signal to which the CP is added is generated.

  The signal processing apparatus according to the present invention converts a multicarrier signal received by an antenna and including a CP (cyclic prefix) on which a plurality of subcarriers orthogonal to each other are superimposed into a baseband received signal. A signal processing device connected to a plurality of radio processing devices to output and a baseband processing device to process a baseband received signal, wherein a plurality of baseband receptions respectively output from the plurality of radio processing devices A Fourier transform processing unit that performs a Fourier transform process on each of the signals, and the plurality of wireless processing devices for a plurality of output signals respectively output from the Fourier transform processing unit and corresponding to the plurality of received signals A plurality of reception weights for controlling reception directivities at a plurality of antennas respectively connected to A reception weight processing unit that generates a new reception signal by adding the plurality of output signals to which the plurality of reception weights are respectively set, and an inverse Fourier transform process on the reception signal generated by the reception weight processing unit And a baseband signal generation unit that generates and outputs a baseband reception signal to which a CP is added based on the signal obtained by the transmission, and the Fourier transform processing unit receives one symbol. A Fourier transform window is set so as to intentionally apply to the CP included in the signal, and the Fourier transform processing unit intentionally applies to the CP included in the received signal for one symbol. A phase change information generation unit that generates phase change information indicating a phase change generated in the received signal by setting a Fourier transform window in And the phase change information generated by the phase change information generating unit, a reception signal output from said baseband signal generation unit and is input to the baseband processor.

  A baseband processing device according to the present invention is a baseband processing device to which the signal processing device is connected, and based on the phase change information output from the signal processing device, from the signal processing device. A correction unit configured to correct the phase change generated in the output reception signal;

  In the aspect of the baseband processing device according to the present invention, a Fourier transform processing unit that performs a Fourier transform process on the received signal output from the signal processing device is provided, and the Fourier transform processing unit is configured to perform the correction. The Fourier transform processing unit corrects the phase change generated in the received signal by setting the position of the Fourier transform window set for the received signal based on the phase information.

  Further, in one aspect of the baseband processing device according to the present invention, a Fourier transform processing unit that performs a Fourier transform process on the reception signal output from the signal processing device is further provided, and the correction unit includes the signal processing Based on the phase change information output from the device, the phase change of the known reception signal output from the Fourier transform processing unit is changed to correct the phase change generated in the reception signal, and the correction unit A deviation amount acquisition unit for obtaining a deviation amount of a reception timing of a signal from a communication counterpart device with which the plurality of wireless processing devices to which the signal processing device is connected is based on the known reception signal corrected in step; Control information for controlling the transmission timing of the communication partner apparatus, which is notified to the communication partner apparatus from the plurality of wireless processing apparatuses, is based on the deviation amount. It is further provided a control information generating unit which generates There are.

  A radio communication apparatus according to the present invention also includes a CP (cyclic prefix) on which a plurality of subcarriers orthogonal to each other received by an antenna are superimposed, the signal processing apparatus described above, the baseband processing apparatus described above. A plurality of wireless processing devices that convert the received multicarrier signals into baseband received signals and output the signals to the signal processing device.

  According to the present invention, it is possible to easily realize a wireless communication apparatus capable of controlling directivity with a plurality of antennas.

FIG. 2 is a diagram showing a configuration of a base station according to Embodiment 1. 3 is a diagram showing a configuration of a communication terminal that communicates with a base station according to Embodiment 1. FIG. 1 is a diagram illustrating a configuration of a baseband processing device according to Embodiment 1. FIG. It is a figure for demonstrating the method of calculating | requiring the deviation | shift amount of the reception timing of the signal from a communication terminal. It is a figure for demonstrating the method of calculating | requiring the deviation | shift amount of the reception timing of the signal from a communication terminal. It is a figure which shows the structure of the base station in which the adaptive array antenna system is not employ | adopted. 1 is a diagram illustrating a configuration of a signal processing device according to Embodiment 1. FIG. 6 is a diagram for explaining a phase change that occurs in a received signal in the signal processing apparatus according to Embodiment 1. FIG. 6 is a diagram for explaining a phase change that occurs in a received signal in the signal processing apparatus according to Embodiment 1. FIG. 6 is a diagram for explaining a phase change that occurs in a received signal in the signal processing apparatus according to Embodiment 1. FIG. 6 is a diagram for explaining a baseband received signal generation method in the signal processing apparatus according to Embodiment 1. FIG. 6 is a diagram illustrating a configuration of a signal processing device according to Embodiment 2. FIG. 6 is a diagram illustrating a configuration of a baseband processing device according to Embodiment 2. FIG. It is a figure for demonstrating the DFT window head position for correction | amendment. It is a figure which shows a mode that a DFT process is performed with respect to a received signal in the baseband processing apparatus which concerns on Embodiment 2. FIG. It is a figure which shows the structure of the baseband processing apparatus which concerns on the modification of Embodiment 2. FIG.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration of a wireless communication apparatus 1 according to the first embodiment. Radio communication apparatus 1 according to the present embodiment is a base station, for example, and communicates with a plurality of communication terminals using OFDM signals. An OFDM signal is a multicarrier signal in which a plurality of subcarriers orthogonal to each other are superimposed. In addition, wireless communication apparatus 1 according to the present embodiment communicates with a communication terminal that is a communication counterpart apparatus using an adaptive array antenna system. Hereinafter, the wireless communication device 1 is referred to as “base station 1”.

  As shown in FIG. 1, the base station 1 includes a plurality of antennas 13 (two antennas 13 in the example of FIG. 1) and a plurality of radio processing devices 10 (two in the example of FIG. 1). A wireless processing device 10), a baseband processing device 11, and a signal processing device 12. The base station 1 can control the directivity of the array antenna 130. The base station 1 is connected to surrounding base stations through a network (not shown).

  The plurality of antennas 13 are connected to the plurality of wireless processing devices 10, respectively. Each wireless processing device 10 performs amplification processing, down-conversion, A / D conversion processing, and the like on the OFDM signal from the communication terminal received by the antenna 13 connected to the wireless processing device 10 to obtain a digital baseband. The received signal is generated and output.

  Each wireless processing device 10 performs D / A conversion processing, up-conversion, amplification processing, and the like on the digital baseband transmission signal (OFDM signal) output from the signal processing device 12. Generate a transmission signal in the analog carrier band. Each wireless processing device 10 inputs the generated transmission signal of the carrier band to the antenna 13 connected to itself. As a result, an OFDM signal is wirelessly transmitted from the array antenna 130 including the plurality of antennas 13 toward the communication terminal 2.

  The baseband processing device 11 generates and outputs a digital baseband transmission signal (OFDM signal) including data to be transmitted. In addition, the baseband processing device 11 performs demodulation processing or the like on the baseband received signal output from the signal processing device 12, and acquires various data included in the received signal. The operation of the baseband processing device 11 will be described in detail later.

  The signal processing device 12 performs a process necessary for controlling the transmission directivity of the array antenna 130 on the transmission signal output from the baseband processing device 11, and performs a plurality of operations corresponding to the plurality of antennas 13. A baseband transmission signal is generated. The plurality of transmission signals generated by the signal processing device 12 are respectively input to the plurality of wireless processing devices 10.

  In addition, the signal processing device 12 performs a process necessary for controlling the reception directivity of the array antenna 130 on the plurality of reception signals respectively output from the plurality of radio processing devices 10, so that the plurality of reception signals are received. A new reception signal obtained by adding the signals is input to the baseband processing device 11 as a new baseband reception signal. The operation of the signal processing device 12 will be described later in detail.

  In the present embodiment, each of the plurality of wireless processing devices 10, the signal processing device 12, and the baseband processing device 11 is housed in a separate casing. Each antenna 13 is installed in a place where there are few obstacles, such as a utility pole or a rooftop of a building, so that a radio signal from a communication terminal can be easily received. Each wireless processing device 10 is arranged as close as possible to the antenna 13 connected to itself. For example, each wireless processing device 10 is arranged on a utility pole, a rooftop of a building, or the like, like the antenna 13. For example, the signal processing device 12 and the baseband processing device 11 are disposed inside a building and are disposed away from the antenna 13 and the wireless processing device 10. Each wireless processing device 10 and the signal processing device 12 and between the signal processing device 12 and the baseband processing device 11 are connected by, for example, an optical fiber cable.

  FIG. 2 is a diagram illustrating a configuration of the communication terminal 2 with which the base station 1 communicates. As shown in FIG. 2, the communication terminal 2 includes an antenna 22, a wireless processing unit 20, and a baseband processing unit 21. In the present embodiment, the wireless processing unit 20 and the baseband processing unit 21 are housed in the same casing.

  The radio processing unit 20 performs amplification processing, down-conversion, A / D conversion processing, and the like on the OFDM signal received from the antenna 22 from the base station 1 to generate a digital baseband received signal. Output. The radio processing unit 20 performs D / A conversion processing, up-conversion, amplification processing, and the like on the digital baseband transmission signal (OFDM signal) output from the baseband processing unit 21. Generate a transmission signal in the analog carrier band. Then, the wireless processing unit 20 inputs the generated transmission signal of the carrier band to the antenna 22. As a result, the OFDM signal is wirelessly transmitted from the antenna 22 toward the base station 1.

  The baseband processing unit 21 generates and outputs a digital baseband transmission signal (OFDM signal) including data to be transmitted. In addition, the baseband processing unit 21 performs demodulation processing or the like on the baseband received signal output from the wireless processing unit 20, and acquires various data included in the received signal.

  Next, the baseband processing device 11 of the base station 1 will be described in detail. FIG. 3 is a diagram showing the configuration of the baseband processing apparatus 11. As illustrated in FIG. 3, the baseband processing device 11 includes a DFT processing unit 110, an IDFT processing unit 111, a CP addition unit 112, a reception data acquisition unit 113, a transmission signal generation unit 114, and a deviation amount acquisition. Part 115.

  The DFT processing unit 110 performs a discrete Fourier transform (DFT) process on the received signal output from the signal processing device 12. More specifically, the DFT processing unit 110 performs a fast Fourier transform (FFT) process on the received signal output from the signal processing device 12. As a result, the DFT processing unit 110 obtains a plurality of complex signals (complex symbols) that respectively modulate a plurality of subcarriers constituting the input reception signal. Hereinafter, a plurality of complex signals that respectively modulate a plurality of subcarriers constituting a reception signal may be referred to as a “reception complex signal sequence”. In addition, each complex signal constituting the reception complex signal sequence may be referred to as a “reception complex signal”. The reception complex signal sequence obtained by the DFT processing unit 110 is input to the reception data acquisition unit 113. Note that the OFDM signal transmitted from the communication terminal 2 includes a CP (cyclic prefix).

  The reception data acquisition unit 113 performs demodulation processing or the like on the input reception complex signal sequence, and converts the reception complex signal sequence into bit data. Thereafter, the reception data acquisition unit 113 performs descrambling processing and decoding processing on the obtained bit data. As a result, the reception data acquisition unit 113 reproduces the bit data for the base station 1 generated by the communication terminal 2. Among the bit data, the bit data for the network is transmitted from the base station 1 to the network.

  The transmission signal generation unit 114 generates bit data for the communication terminal 2 including bit data from the network, and performs encoding processing and scrambling processing on the bit data. Then, the transmission signal generation unit 114 converts the processed bit data into a plurality of complex signals on the IQ plane corresponding to a plurality of subcarriers constituting the OFDM signal. The plurality of complex signals are input to the IDFT processing unit 111 as a transmission complex signal sequence. Hereinafter, each complex signal constituting the transmission complex signal sequence may be referred to as a “transmission complex signal”.

  The IDFT processing unit 111 performs an inverse discrete Fourier transform (IDFT: Inverse DFT) on the input transmission complex signal sequence. More specifically, the IDFT processing unit 111 performs an inverse fast Fourier transform (IFFT) process on the input transmission complex signal sequence. As a result, the IDFT processing unit 111 obtains a baseband OFDM signal on which a plurality of subcarriers each modulated by a plurality of transmission complex signals (complex symbols) constituting a transmission complex signal sequence are superimposed. The baseband transmission signal generated by the IDFT unit 111 is input to the CP adding unit 112.

  CP adding section 112 adds a CP to the input transmission signal and outputs the transmission signal to signal processing device 12. The CP adding unit 112 copies the last part of the OFDM symbol (an OFDM signal for one symbol) to be input, and adds it as a CP before the OFDM symbol. For example, the CP adding unit 112 copies the last one-eighth portion of the OFDM symbol and adds it as a CP before the OFDM symbol. Hereinafter, the term “OFDM symbol” means an OFDM symbol including a CP (an OFDM symbol to which a CP is added) unless otherwise specified.

  The deviation amount acquisition unit 115 obtains a deviation amount from the reference timing, which is the original reception timing, for the reception timing of the reception signal at the base station 1. This deviation amount can be obtained based on a known received complex signal output from the DFT processing unit 110. Hereinafter, how to determine the amount of shift in reception timing will be described with reference to FIGS.

  4 and 5, an I (Inphase) component and a Q (Quadrature) component of one subcarrier modulated by a known complex signal among a plurality of subcarriers constituting the OFDM symbol input to the DFT processing unit 110. Is shown on the left. Also, on the right side of FIGS. 4 and 5, a known complex that modulates the subcarrier obtained as a result of DFT processing performed by the DFT processing unit 110 on the OFDM symbol including the subcarrier shown on the left side is shown. The signal is shown on the IQ plane. FIG. 4 shows an example in which there is no deviation in the reception timing of the signal from the communication terminal 2, that is, the communication terminal 2 is transmitting a signal at an appropriate transmission timing. FIG. 5 shows an example in which the reception timing of the signal from the communication terminal 2 is early, that is, the transmission timing of the communication terminal 2 is early.

  In DFT processing section 110 according to the present embodiment, when a DFT processing window (hereinafter referred to as “DFT window”) is set for an OFDM symbol, there is no deviation in the reception timing of the OFDM symbol. In such a case, a DFT window is set for the OFDM symbol at a timing related to the CP included in the OFDM symbol. That is, the DFT processing unit 110 sets the DFT window so as to intentionally cover the CP included in the OFDM symbol. The DFT window indicates a range in which DFT processing is actually performed in the OFDM symbol. When the DFT window is set only for the effective symbols that are signals included in the OFDM symbol, which is the original signal for one symbol, when the reception timing of the OFDM symbol is a little earlier, the DFT window extends over the subsequent OFDM symbols. Is set, and an interference wave is detected. In the present embodiment, since the DFT window is set for the OFDM symbol so that the CP included in the OFDM symbol is intentionally applied, even if the reception timing of the OFDM symbol becomes earlier, the subsequent OFDM symbol It is possible to prevent the DFT window from being set over the two.

  In addition, when the device on the transmission side transmits an OFDM signal, by performing filtering (waveform shaping) on the two OFDM symbols so as to smooth the waveform of the boundary portion between two consecutive OFDM symbols, Even when the DFT window is set across two OFDM symbols in the receiving apparatus, the detected interference wave can be suppressed. By multiplying the two OFDM symbols by, for example, a window function having a cosine roll-off characteristic, the waveform of the boundary portion between the two OFDM symbols can be smoothed. In the present embodiment, even if the reception timing of the OFDM symbol from the communication terminal 2 becomes earlier in the base station 1, it is possible to suppress the setting of the DFT window across the subsequent OFDM symbols. 2 does not need to perform such filtering on the transmission signal.

  If the reception timing of the signal from the communication terminal 2 is shifted, the DFT processing unit 110 shifts the position of the DFT window with respect to the received signal, so that the phase of the known reception complex signal output from the DFT processing unit 110 is the original phase ( The phase changes when there is no deviation in the reception timing. The amount of change in phase changes according to the amount of shift in reception timing. Therefore, the shift amount acquisition unit 115 calculates the shift amount of the reception timing of the signal from the communication terminal 2 based on the change amount from the original phase with respect to the phase of the known reception complex signal output from the DFT processing unit 110. Can be sought.

  The transmission signal generation unit 114 is notified of the shift amount obtained by the shift amount acquisition unit 115. The transmission signal generation unit 114 generates control information for controlling the transmission timing of the communication terminal 2 based on the deviation amount of the reception timing of the signal from the communication terminal 2 notified from the deviation amount acquisition unit 115. . For example, when the reception timing of the signal from the communication terminal 2 is earlier than the original reception timing, control information that instructs the communication terminal 2 to delay the transmission timing is generated by the earlier timing. . On the other hand, when the reception timing of the signal from the communication terminal 2 is later than the original reception timing, control information for instructing the communication terminal 2 to advance the transmission timing is generated by that delay. The When the transmission signal generation unit 114 generates control information, the transmission signal generation unit 114 generates and outputs a transmission signal (transmission complex signal sequence) including the control information. Thereby, the control information of the transmission timing is notified from the base station 1 to the communication terminal 2.

  In the communication terminal 2, when the radio processing unit 20 receives a signal including control information on transmission timing, the baseband processing unit 21 transmits the transmission timing of the radio processing unit 20 to the base station 1 according to the content of the control information. To control. Thereby, the base station 1 can receive the OFDM signal from the communication terminal 2 at the original reception timing, and can set the DFT window at an appropriate position with respect to the OFDM signal. Therefore, the base station 1 can accurately acquire various data included in the OFDM signal from the communication terminal 2.

<Details of signal processing device>
In the present embodiment, as shown in FIG. 6, an adaptive array antenna system is realized by directly connecting one radio processing device 10 connected to the antenna 13 and the baseband processing device 11 with an optical fiber cable or the like. A base station (hereinafter referred to as “non-array-capable base station”) 200 that is not employed can be realized. Specifically, the reception signal output from the wireless processing device 10 is input to the DFT processing unit 110 of the baseband processing device 11 instead of the reception signal output from the signal processing device 12, and the baseband processing device 11. The non-array-compatible base station 200 can be realized by inputting the transmission signal output from the CP adding unit 112 to the wireless processing device 10 instead of the transmission signal output from the signal processing device 12. As shown in FIG. 1, an adaptive array antenna system is obtained by connecting a plurality of radio processing devices 10 and a baseband processing device 11 to which a plurality of antennas 13 are respectively connected to a signal processing device 12. Can be realized (hereinafter, sometimes referred to as “array-compatible base station 1”).

  Thus, in the present embodiment, the presence of the signal processing device 12 allows the baseband processing device 11 to have the same configuration between the array non-compliant base station 200 and the array compatible base station 1. The array-compatible base station 1 can be easily realized.

  For example, at least one radio processing device 10 and a signal processing device 12 to which an antenna 13 is connected are added to an existing non-array-capable base station 200, and each radio processing device 10 and the signal processing device 12 are connected. By connecting the signal processing device 12 and the baseband processing device 11, the array-compatible base station 1 can be easily realized from the non-array-compatible base station 200.

  In addition, when both the non-array-capable base station 200 and the array-capable base station 1 are prepared so that the user can select a favorite base station from both devices, other than the signal processing device 12 Since elements can be shared between the array non-compliant base station 200 and the array compatible base station 1, each of the non-array compatible base station 200 and the array compatible base station 1 can be easily realized. Below, the structure of this characteristic signal processing apparatus 12 is demonstrated in detail.

  FIG. 7 is a diagram illustrating the configuration of the signal processing device 12. As illustrated in FIG. 7, the signal processing device 12 includes a DFT processing unit 120, a reception weight processing unit 121, and a baseband signal generation unit 122 as elements for processing the received signal. The signal processing device 12 includes a DFT processing unit 125, a transmission weight processing unit 126, and a baseband signal generation unit 127 as elements for processing the transmission signal.

  The DFT processing unit 120 performs DFT processing, more specifically, FFT processing, on the reception signal output from each wireless processing device 10. As a result, the DFT processing unit 120 obtains a plurality of reception complex signals (reception complex signal sequences) that respectively modulate a plurality of subcarriers constituting the reception signal for each input reception signal.

  The reception weight processing unit 121 uses, for example, MMSE (least square error method) to set reception weights to be set for a plurality of reception complex signal sequences output from the DFT processing unit 120, that is, reception signals from the plurality of antennas 13. calculate. The reception weight can be calculated based on a known complex signal included in the signal from the communication terminal 2.

  The reception weight processing unit 121 sets (complex multiplication) a corresponding reception weight for each of the plurality of reception complex signals constituting the reception complex signal sequence for each of the plurality of input reception complex signal sequences. . Then, reception weight processing section 121 adds a plurality of reception complex signals after setting reception weights for the same subcarrier included in the plurality of reception complex signal sequences. Thereby, the beam related to the reception directivity of the array antenna 130, that is, the beam related to the reception directivity of the plurality of antennas 13 as a whole, is directed to one subcarrier (desired wave) from the specific communication terminal 2, With respect to the one subcarrier, a reception complex signal from which interference components are removed can be acquired. That is, interference components are removed from a new received complex signal obtained by adding together a plurality of received complex signals after setting reception weights for the same subcarrier included in a plurality of received complex signal sequences. Reception weight processing section 121 acquires and outputs a reception complex signal from which interference waves have been removed for each of a plurality of subcarriers constituting the reception signal.

  As described above, by setting the reception weight to the reception signal from the communication terminal 2, the beam related to the reception directivity of the array antenna 130 is directed to the communication terminal 2, and the data transmitted from the communication terminal 2 is changed. It will be possible to receive properly.

  The baseband signal generation unit 122 generates a baseband reception signal that can be processed by the baseband processing device 11 from the reception complex signal sequence output from the reception weight processing unit 121. The baseband signal generation unit 122 performs IDFT processing, more specifically IFFT processing, on the reception complex signal sequence output from the reception weight processing unit 121. Thereby, the baseband signal generation unit 122 obtains a baseband OFDM signal on which a plurality of subcarriers modulated with a plurality of reception complex signals constituting a reception complex signal sequence are superimposed. Then, the baseband signal generation unit 122 performs predetermined processing to be described later on the obtained OFDM signal, generates an OFDM signal to which a CP is added, and outputs the OFDM signal to the baseband processing device 11.

  The DFT processing unit 125 performs DFT processing, more specifically FFT processing, on the transmission signal output from the baseband processing device 11. As a result, the DFT processing unit 125 obtains a plurality of transmission complex signals (transmission complex signal sequences) that respectively modulate a plurality of subcarriers constituting the input transmission signal.

  The transmission weight processing unit 126 prepares the input transmission complex signal sequence for the number of antennas 13 (two in this example). The plurality of transmission complex signal sequences are transmitted from the plurality of antennas 13, respectively. The transmission weight processing unit 126 calculates a transmission weight set for each transmission complex signal sequence, in other words, a transmission weight set for a transmission signal transmitted from each antenna 13. The transmission weight can be calculated based on the reception weight calculated by the reception weight processing unit 121. Specifically, the transmission weight processing unit 126 corrects the reception weight calculated by the reception weight processing unit 121 based on the calibration information, and uses the corrected reception weight as the transmission weight. The calibration information is information generated based on a difference in characteristics between the transmission system circuit and the reception system circuit in the base station 1. Although the reception weight obtained by the reception weight processing unit 121 can be used as a transmission weight as it is, there is a difference in characteristics between the transmission system circuit and the reception system circuit (for example, the amplification unit of the transmission system circuit and the reception system circuit). Therefore, the optimal transmission weight can be obtained by correcting the reception weight so as to absorb the difference using the calibration information.

  The transmission weight processing unit 126 sets (complex multiplication) the corresponding transmission weight for each of the plurality of transmission complex signals constituting the transmission complex signal sequence for each of the generated plurality of transmission complex signal sequences. Then, transmission weight processing section 126 outputs a plurality of transmission complex signal sequences after setting transmission weights. Thus, by setting the transmission weight for the transmission signal directed to the communication terminal 2, the beam related to the transmission directivity of the array antenna 130 is directed to the communication terminal 2. It becomes possible to transmit data appropriately.

  The baseband signal generation unit 127 includes an IDFT processing unit 128 and a CP adding unit 129. The IDFT processing unit 128 performs IDFT processing, more specifically IFFT processing, on each of the plurality of transmission complex signal sequences output from the transmission weight processing unit 126. Thereby, in the IDFT processing unit 128, for each of a plurality of input transmission complex signal sequences, a baseband in which a plurality of subcarriers modulated with a plurality of transmission complex signals constituting the transmission complex signal sequence are superimposed. An OFDM signal is obtained. A plurality of baseband transmission signals (OFDM signals) generated by the IDFT processing unit 128 are input to the CP adding unit 129. CP adding section 129 adds a CP for each symbol to the transmission signal for each of a plurality of input transmission signals. Similar to CP adding section 112 described above, CP adding section 129 copies the last part of the input OFDM symbol and adds it as a CP before the OFDM symbol. The plurality of transmission signals to which the CP is added by the CP adding unit 129 are respectively input to the plurality of radio processing apparatuses 10.

  As described above, the signal processing device 12 performs the processing necessary for transmitting the baseband transmission signal output from the baseband processing device 11 by the adaptive array antenna method, and each radio processing device 10 A baseband transmission signal that can be processed is generated. Further, the signal processing device 12 can process the baseband processing device 11 by performing processing necessary to receive the baseband reception signal output from each wireless processing device 10 using the adaptive array antenna method. Generate a baseband received signal. Therefore, by connecting the radio processing device 10 and the baseband processing device 11 that can be used in the non-array-capable base station 200 to the signal processing device 12, the array-corresponding base station 1 can be easily realized.

<Method for correcting phase change generated in signal processing apparatus>
In the DFT processing unit 120 of the signal processing device 12, as in the DFT processing unit 110 of the baseband processing device 11, it is assumed that the DFT window has no shift in the reception timing of the OFDM symbol for the input OFDM symbol. In some cases, the timing is set so that the CP included in the OFDM symbol is related to the CP. For this reason, the phase of the received signal received by the array antenna 130 changes in the signal processing device 12. Specifically, the phase of each of a plurality of reception complex signals that respectively modulate a plurality of subcarriers constituting the OFDM symbol received by the array antenna 130 changes in the signal processing device 12.

  8 and 9 are diagrams illustrating how the phase of the reception complex signal changes in the signal processing device 12. In FIG. 8, attention is paid to a certain subcarrier among a plurality of subcarriers constituting an OFDM symbol received by the array antenna 130, and I of the target subcarrier when the target subcarrier is received by the array antenna 130. The component and Q component are shown on the left. On the right side of FIG. 8, the reception complex signal for modulating the subcarrier of interest shown on the left side is shown on the IQ plane.

  In FIG. 9, the I component and Q component of the target subcarrier included in the OFDM symbol input to the DFT processing unit 120 are shown on the left side. On the right side of FIG. 9, as a result of the DFT processing performed by the DFT processing unit 120 on the OFDM symbol including the target subcarrier shown on the left side, reception that modulates the target subcarrier obtained by the DFT processing unit 120 is performed. The complex signal is shown on the IQ plane. 8 and 9, it is assumed that there is no deviation in the reception timing of the signal from the communication terminal 2. Also in FIGS. 10, 11, 14, and 15 described later, it is assumed that there is no deviation in the reception timing of the signal from the communication terminal 2.

  As shown in FIG. 9, in the DFT processing unit 120, a DFT window is set for an OFDM symbol so as to intentionally apply to a CP included in the OFDM symbol. The respective phases of a plurality of reception complex signals that respectively modulate the carriers are changed from the state when the signals are received by the array antenna 130 (see FIG. 8). 8 and 9, the phase of the reception complex signal that modulates the target subcarrier is changed from 0π (radian) to −π / 4 (radian) by the DFT processing in the DFT processing unit 120. On the other hand, if the DFT processing unit 120 sets a DFT window only for the effective symbol for an OFDM symbol, a plurality of received complex signals that respectively modulate a plurality of subcarriers constituting the OFDM symbol. The phase of each of the signals coincides with the state when received by the array antenna 130 (see FIG. 8). Note that α shown in FIG. 9 is a portion of the DFT window that depends on the CP of the OFDM symbol when the DFT processing unit 120 sets the DFT window for the OFDM symbol with no deviation in reception timing. Shows the length of time. Hereinafter, this α is referred to as “CP protrusion time length α”.

  When the phase of the received signal changes due to the DFT processing in the DFT processing unit 120, the received signal is input to the reception weight processing unit 121 with the phase changed. Therefore, the received signal is also input to the baseband signal generation unit 122 with the phase changed. As a result, unless the baseband signal generation unit 122 performs special processing, the received signal is also input to the baseband processing device 11 with the phase changed. FIG. 10 is a diagram showing this state.

  In the upper half of FIG. 10, the baseband signal generation unit 122 is included in the OFDM symbol (OFDM symbol not including CP) obtained by performing IDFT processing on the input reception signal (reception complex signal sequence). The I and Q components of the noted subcarrier are shown on the left side. On the right side of the upper half of FIG. 10, the reception complex signal for modulating the subcarrier of interest shown on the left side is shown on the IQ plane.

  Also, in the lower half of FIG. 10, the baseband signal generation unit 122 is shown on the left side of the upper half of FIG. 10, that is, an OFDM symbol obtained by performing IDFT processing on the input received signal. For an OFDM symbol that does not include a CP and includes a target subcarrier, a target subcarrier included in a new OFDM symbol obtained by adding a copy A ′ of the last part A as a CP before the OFDM symbol. The I and Q components are shown on the left. On the right side of the lower half of FIG. 10, the reception complex signal for modulating the subcarrier of interest shown on the left side is shown on the IQ plane. In the target subcarrier shown on the left side of the lower half of FIG. 10, the portion of the target subcarrier shown on the left side of the upper half of FIG.

  As shown in FIG. 10, in the baseband signal generation unit 122, if a copy A ′ for the last part A of an OFDM symbol that does not include a CP is added as a CP before the OFDM symbol, As can be understood from a comparison between FIG. 8 and FIG. 10, each received complex signal is output from the baseband signal generation unit 122 with its phase changed, and input to the baseband processing device 11.

  When a reception signal whose phase has changed from the state when it was received by the array antenna 130 is input to the baseband processing device 11, it is received by the array antenna 130 from the DFT processing unit 110 of the baseband processing device 11. The received complex signal whose phase has changed from the state when the signal is generated is output. The phase of the known received complex signal changes from the state when it is received by the array antenna 130, and the baseband processing device 11 does not recognize it and based on the known received complex signal, the communication terminal 2. If the amount of deviation of the reception timing of the signal from is obtained, the accuracy of calculating the amount of deviation decreases. As a result, it becomes difficult to accurately control the transmission timing of the communication terminal 2.

  Therefore, the baseband signal generation unit 122 according to the present embodiment inputs the CP that is input to the baseband processing device 11 so that the phase change generated in the reception signal by the DFT processing in the DFT processing unit 120 is corrected. An added baseband OFDM signal is generated. Hereinafter, the correction processing in the baseband signal generation unit 122 will be described.

  FIG. 11 is a diagram for explaining the correction processing in the baseband signal generation unit 122. In the upper half of FIG. 11, as in the upper half of FIG. 10, the baseband signal generation unit 122 performs an OFDM symbol (an OFDM symbol not including a CP) obtained by performing IDFT processing on the input received signal. The I component and Q component of the subcarrier of interest included in () are shown on the left side. On the right side of the upper half of FIG. 11, the reception complex signal for modulating the subcarrier of interest shown on the left side is shown on the IQ plane.

  In the lower half of FIG. 11, the I component and Q component of the subcarrier of interest included in the OFDM symbol to which the CP is output, output from the baseband signal generation unit 122, are shown on the left side. Further, on the right side of the lower half of FIG. 11, a reception complex signal for modulating the subcarrier of interest shown on the left side is shown on the IQ plane. In the target subcarrier shown on the left side of the lower half of FIG. 11, the portion of the target subcarrier shown on the left side of the upper half of FIG. 11 is indicated by a bold line.

  In baseband signal generation section 122 according to the present embodiment, each OFDM symbol obtained by performing IDFT processing on the input received signal (including the target subcarrier shown on the left side of the upper half of FIG. 11) , OFDM symbol not including CP), a copy X ′ of the last part X of the OFDM symbol is added before the OFDM symbol, and a copy Y ′ of the first part Y of the OFDM symbol is added to the OFDM symbol. By adding it to the back, a baseband OFDM signal with a CP added is generated. As a result, a reception signal that is input to the baseband processing device 11 in which a phase change generated in the reception signal by the DFT processing in the DFT processing unit 120 is corrected is obtained.

  As shown in the lower half of FIG. 11, the phase of the reception complex signal that is output from the baseband signal generation unit 122 and modulates the subcarrier of interest included in the OFDM symbol to which the CP is added is the above-described FIG. The phase of the received complex signal shown on the right side of the received complex signal coincides with the phase of the received complex signal that modulates the target subcarrier when the target subcarrier is received by the array antenna 130. From this, it can be understood that the phase change generated by the DFT processing in the DFT processing unit 120 is corrected in the reception signal output from the baseband signal generation unit 122.

  The time length y of the first part Y of the OFDM symbol to which the copy Y ′ is added to the OFDM symbol not including the CP is expressed by the following equation (1).

y = α (1)
Here, as described above, when the DFT processing unit 120 sets a DFT window for an OFDM symbol in which there is no shift in reception timing, the CP protrusion time length α is set to the CP of the OFDM symbol in the DFT window. The time length of the part applied to is shown (see FIG. 9).

  Then, the time length x of the last part X of the OFDM symbol to which the copy X ′ is added to the OFDM symbol not including the CP is expressed by the following equation (2).

x = β−α (2)
Here, β represents the time length of CP.

  By setting the time lengths x and y in this way, as shown in FIG. 11, an OFDM symbol composed of a CP and a valid symbol having a time length determined in the radio communication system to which the base station 1 belongs. Thus, the baseband signal generation unit 122 can generate an OFDM symbol in which the phase change generated by the DFT processing in the DFT processing unit 120 is corrected.

  As described above, in the present embodiment, the signal processing device 12 performs the processing necessary for transmitting the baseband transmission signal output from the baseband processing device 11 using the adaptive array antenna method. The baseband transmission signal that can be processed by each wireless processing device 10 is generated. Therefore, by connecting the radio processing device 10 and the baseband processing device 11 that can be used in the non-array-capable base station 200 to the signal processing device 12, the base station 1 that can transmit by the adaptive array antenna method. Can be realized easily.

  Further, the signal processing device 12 can process the baseband processing device 11 by performing processing necessary for receiving the baseband reception signal output from each wireless processing device 10 using the adaptive array antenna method. The baseband received signal is generated. Therefore, by connecting the radio processing apparatus 10 and the baseband processing apparatus 11 that can be used in the non-array-capable base station 200 to the signal processing apparatus 12, the base station 1 that can receive by the adaptive array antenna system. Can be realized easily.

  Also, in the baseband signal generation unit 122 according to the present embodiment, the baseband received signal to which the CP is added is corrected so that the phase change generated in the received signal by the DFT processing in the DFT processing unit 120 is corrected. Therefore, a received signal having a small phase change from when it is received by the array antenna 130 can be input to the baseband processing device 11. Therefore, in the baseband processing apparatus 11, the calculation accuracy of the shift amount of the reception timing of the signal from the communication terminal 2 is improved. As a result, the base station 1 can accurately control the transmission timing of the communication terminal 2.

<Modification of Embodiment 1>
<First Modification>
In the baseband signal generation unit 122 according to the present modification, the phase generated in the reception signal by the DFT processing in the DFT processing unit 120 by changing the phase of the input frequency domain reception signal (reception complex signal sequence). Compensate for changes. Hereinafter, the operation of the baseband signal generation unit 122 according to this modification will be described in detail.

  The baseband signal generation unit 122 sets the phase of each reception complex signal constituting the reception complex signal sequence output from the reception weight processing unit 121 to the above-described CP protrusion time length α in the DFT processing unit 120 (see FIG. 9). Change based on. Since the phase change amount generated in the received signal by the DFT processing in the DFT processing unit 120 depends on the CP protrusion time length α, the phase of each reception complex signal output from the reception weight processing unit 121 is determined as the CP protrusion time length α. Therefore, the phase change that occurs in the received signal due to the DFT processing in the DFT processing unit 120 can be corrected. When changing the phase of a certain received complex signal based on the CP protrusion time length α, the baseband signal generation unit 122 assumes that the period of the subcarrier corresponding to the received complex signal is T, and The phase is rotated counterclockwise by (2π × α / T) radians on the IQ plane. As a result, the phase of the reception complex signal coincides with the phase when received by the array antenna 130, and the phase change generated in the reception signal by the DFT processing in the DFT processing unit 120 is corrected.

  For example, if the reception complex signal shown on the right IQ plane in FIG. 9 is a reception complex signal output from the reception weight processing unit 121, the phase of the reception complex signal is (2π × α / T). By rotating it counterclockwise by radians, the phase of the received complex signal matches the phase when received by the array antenna 130 shown on the right side of FIG.

  When the phase of the reception complex signal sequence is corrected based on the time length α, the baseband signal generation unit 122 performs IDFT processing on the reception complex signal sequence to generate a baseband OFDM signal. Then, similarly to CP adding section 129, baseband signal generation section 122 copies the last part of the OFDM symbol for each OFDM symbol (OFDM symbol not including CP) included in the generated baseband OFDM signal. Then, it is added as a CP before the OFDM symbol. As a result, a baseband received signal to which a CP is added, in which the phase change generated by the DFT processing in the DFT processing unit 120 is corrected, is obtained.

  In the case of this modification, it is necessary to individually change the phases of a plurality of reception complex signals constituting the reception complex signal sequence. On the other hand, in the method for generating an OFDM signal including a CP described with reference to FIG. 11, processing is performed on the entire OFDM signal, not on each subcarrier individually. Therefore, the process in the baseband signal generation unit 122 is simplified by the method described with reference to FIG.

<Second Modification>
Similarly to the DFT processing unit 120, the DFT processing unit 125 of the signal processing device 12 also assumes that the OFDM symbol (transmission signal) does not have a shift in the reception timing of the OFDM symbol (transmission signal). When the DFT window is set at a timing related to the CP included in the DFT processing, the DFT processing in the DFT processing unit 125 causes a phase change in the transmission signal. Therefore, in this case, the CP is set so that the baseband signal generation unit 127 corrects the phase change generated in the transmission signal by the DFT processing in the DFT processing unit 125, similarly to the baseband signal generation unit 122. An added baseband transmission signal may be generated. Hereinafter, the operation of the baseband signal generation unit 127 according to this modification will be described.

  The baseband signal generation unit 127 performs IDFT processing on the transmission signal for each of the plurality of transmission signals respectively output from the transmission weight processing unit 126 and corresponding to the plurality of antennas 13. Then, for each input transmission signal, the baseband signal generation unit 127 performs, for each OFDM symbol (OFDM symbol not including CP) obtained by performing IDFT processing on the transmission signal, the last of the OFDM symbol. By adding a copy X ′ of the part X before the OFDM symbol and by adding a copy Y ′ of the first part Y of the OFDM symbol after the OFDM symbol, transmission of the baseband with the CP added Generate a signal.

  The time length y of the first part Y of the OFDM symbol to which the copy Y ′ is added to the OFDM symbol not including the CP is given by the above equation (1). However, in this case, when the DFT processing unit 125 sets a DFT window for the OFDM symbol, the CP protrusion time length α indicates a time length of a portion of the DFT window that covers the CP of the OFDM symbol. It will be. Then, the time length x of the last part X of the OFDM symbol to which the copy X ′ is added to the OFDM symbol not including the CP is given by the above equation (2).

  By setting the time lengths x and y in this way, an OFDM symbol composed of a CP and a valid symbol having a time length determined in the system, and a phase generated by DFT processing in the DFT processing unit 125 The baseband signal generation unit 127 can generate a transmission OFDM symbol whose change is corrected.

  Similar to the first modification, the baseband signal generation unit 127 changes the phase of the input frequency domain transmission signal (transmission complex signal sequence), thereby performing the DFT processing in the DFT processing unit 125. Thus, the phase change generated in the transmission signal may be corrected. In this case, the baseband signal generation unit 127 uses the DFT processing unit 125 to set the phase of each transmission complex signal constituting the transmission complex signal sequence for each transmission complex signal sequence output from the transmission weight processing unit 126. Is changed based on the protrusion time length α. When changing the phase of a certain transmission complex signal based on the CP protrusion time length α, the baseband signal generation unit 127 assumes that the period of the subcarrier corresponding to the transmission complex signal is T, and The phase is rotated counterclockwise by (2π × α / T) radians on the IQ plane. As a result, the phase of the transmission complex signal coincides with the phase generated by the baseband processing device 11, and the phase change generated in the transmission signal is corrected by the DFT processing in the DFT processing unit 125. .

  When the phase of each transmission complex signal sequence is corrected based on the CP protrusion time length α, the baseband signal generation unit 127 performs IDFT processing on the transmission complex signal sequence to generate a baseband OFDM signal. Then, as with the above-described CP adding unit 129, the baseband signal generation unit 127 performs the last part of the OFDM symbol for each OFDM symbol (OFDM symbol not including the CP) included in the generated baseband OFDM signal. Is added as a CP before the OFDM symbol. As a result, a baseband transmission signal to which a CP is added, in which the phase change generated by the DFT processing in the DFT processing unit 125 is corrected, is obtained.

Embodiment 2. FIG.
12 and 13 are diagrams respectively showing configurations of the signal processing device 12 and the baseband processing device 11 of the base station 1 according to the second embodiment. In the base station 1 according to the present embodiment, the baseband processing device 11 corrects the phase change of the received signal generated by the DFT processing in the signal processing device 12. Below, the base station 1 which concerns on this Embodiment is demonstrated centering on difference with the base station 1 which concerns on the above-mentioned Embodiment 1. FIG.

  As shown in FIG. 12, the signal processing device 12 according to the second embodiment includes a baseband signal generation unit 322 instead of the baseband signal generation unit 122 in the signal processing device 12 according to the first embodiment. In addition, a phase change information generation unit 325 is further provided.

  Unlike the baseband signal generation unit 122 according to Embodiment 1, the baseband signal generation unit 322 does not correct the phase change that occurs in the reception signal due to the DFT processing in the DFT processing unit 120. The baseband signal generation unit 322 includes an IDFT processing unit 323 and a CP addition unit 324.

  The IDFT processing unit 323 performs IDFT processing, more specifically, IFFT processing, on the reception signal output from the reception weight processing unit 121. As a result, the IDFT processing unit 323 obtains a baseband OFDM signal on which a plurality of subcarriers modulated with a plurality of reception complex signals constituting the input reception signal (reception complex signal sequence) are superimposed. CP adding section 324 adds a CP for each symbol to the baseband received signal generated by IDFT processing section 323. Similar to CP adding section 129, CP adding section 324 copies the last part of the input OFDM symbol that does not include CP, and adds it as a CP before the OFDM symbol. As a result, the baseband signal generation unit 322 generates a baseband reception signal to which the CP is added, and outputs the generated baseband signal to the baseband processing device 11.

  As described above, in the signal processing device 12, the phase change generated in the received signal due to the DFT processing is not corrected. Therefore, the phase as shown in FIG. 9 described above is used for the baseband processing device 11. A received signal in which a change has occurred is input.

  The phase change information generation unit 325 generates phase change information indicating the phase change that occurs in the received signal by the DFT processing in the DFT processing unit 120. The phase change information generation unit 325 generates phase change information based on the CP protrusion time length α in the DFT processing unit 120. This phase change information is input to the baseband processing device 11 together with the reception signal generated by the baseband signal generation unit 322.

  As shown in FIG. 13, the baseband processing apparatus 11 according to the present embodiment is a baseband processing apparatus 11 according to the first embodiment, in which a DFT processing unit 410 is provided instead of the DFT processing unit 110. is there.

  The DFT processing unit 410 performs DFT processing, specifically, FFT processing, on the baseband received signal output from the signal processing device 12. At this time, the DFT processing unit 410 sets the DFT window so that the phase change occurring in the received signal is corrected based on the phase change information output from the signal processing device 12. As a result, the DFT processing unit 410 obtains a reception complex signal sequence in which the phase change generated in the signal processing device 12 is corrected. This reception complex signal sequence is input to the reception data acquisition unit 113.

  In addition, when the radio processing apparatus 10 is directly connected to the signal processing apparatus 12 as in the non-array-capable base station 200, the phase of the received signal that occurs when the radio processing apparatus 10 is connected via the signal processing apparatus 12 is used. Since no change occurs, the DFT processing unit 410 sets the DFT window so that it is intentionally applied to the CP. When the phase change information is input, the baseband processing device 11 determines that the signal processing device 12 is connected to itself, and the DFT processing unit 410 sets the DFT window based on the phase change information. On the other hand, when the phase change information is not input, the baseband processing device 11 determines that the signal processing device 12 is not connected to itself, that is, determines that the wireless processing device 10 is directly connected, The DFT processing unit 410 sets the DFT window so that it is intentionally applied to the CP by the CP protrusion time length α.

  The signal processing device 12 may output a connection notification signal for notifying that the own device is connected to the baseband processing device 11 separately from the phase change information. In this case, the baseband processing device 11 determines whether or not the signal processing device 12 is connected depending on whether or not the connection notification signal is input.

  Next, an example of a method for generating phase change information will be described. FIG. 14 is a diagram for explaining a method of generating phase change information. In FIG. 14, the I component and the Q component of the target subcarrier included in the baseband received signal generated by the baseband signal generation unit 322 are shown on the left side. On the right side of FIG. 14, a reception complex signal for modulating the target subcarrier shown on the left side is shown on the IQ plane.

  In the present embodiment, in the DFT processing unit 410 of the baseband processing device 11, the leading position of the DFT window (DFT processing calculation start position) at which the phase change occurring in the received signal is corrected is the CP protrusion time. Calculated based on the length α. Information indicating the head position of the DFT window is used as phase change information indicating the phase change. Hereinafter, the leading position of the DFT window where the phase change occurring in the received signal is corrected in the DFT processing unit 410 is referred to as a “correcting DFT window leading position”.

  The DFT window head position for correction corresponds to the phase change generated in the received signal from the head position of the DFT window used in the DFT processing unit 410 when the radio processing device 10 is directly connected to the baseband processing device 11. The amount of CP, which is a large amount, is set behind by the protrusion time length α. In this example, in the DFT processing unit 410, when the wireless processing device 10 is directly connected to the baseband processing device 11, the DFT window is set so as to intentionally cover the CP by the CP protrusion time length α. Therefore, the head of the effective symbol (the end of the CP when the reception timing of the received signal is not deviated as shown in FIG. ). The phase change information generation unit 325 generates information indicating the head position of the correction DFT window determined in this way as phase change information.

  FIG. 15 is a diagram illustrating how the DFT processing unit 410 of the baseband processing apparatus 11 performs DFT processing on a received signal. In FIG. 15, the I component and Q component of the subcarrier of interest included in the reception signal input to the DFT processing unit 410 (the baseband reception signal generated by the baseband signal generation unit 322) are shown on the left side. . On the right side of FIG. 15, the DFT processing unit 410 performs DFT processing on the OFDM symbol including the target subcarrier shown on the left side. As a result, the reception complex that modulates the target subcarrier obtained by the DFT processing unit 410 is received. The signal is shown on the IQ plane. In FIG. 15, the range of the DFT window in the DFT processing unit 410 when the signal processing device 12 is connected to the baseband processing device 11 is indicated by a solid line, and the wireless processing device 10 is directly connected to the baseband processing device 11. The range of the DFT window in the DFT processing unit 410 when connected is indicated by a broken line.

  As shown in FIG. 15, the DFT window head position in the DFT processing unit 410 is a correction DFT window head position indicated by the phase change information, that is, an effective symbol when there is no deviation in the reception timing of the received signal. Set to the beginning of. As a result, in the received signal output from the DFT processing unit 410, the phase change generated in the signal processing device 12 is corrected.

  As the phase change information, information other than information indicating the head position of the correction DFT window may be used. For example, when the signal processing device 12 assumes that no phase change occurs in the received signal, the head position of the effective symbol included in the OFDM symbol in the received signal (hereinafter referred to as “original effective symbol head position”). ) May be adopted as the phase change information. In the OFDM symbol shown on the left side of FIG. 14, that is, in the case where there is no deviation in the reception timing of the signal from the communication terminal 2, the OFDM symbol included in the baseband reception signal generated by the baseband signal generation unit 322 The position after the CP protruding time length α from the head position of the effective symbol is the head position of the original effective symbol.

  The DFT processing unit 410 of the baseband processing device 11 sets the DFT window so that the phase change generated in the received signal is corrected based on the head position of the original effective symbol indicated by the phase change information. Specifically, the DFT processing unit 410 sets the start position of the DFT window at a position that is a CP protrusion time length α before the start position of the original effective symbol indicated by the phase change information. As a result, the head position of the DFT window in the DFT processing unit 410 is set to the head of the effective symbol when there is no deviation in the reception timing of the received signal, as shown in FIG. As a result, in the reception signal output from the DFT processing unit 410, the phase change generated in the signal processing device 12 is corrected.

  As described above, in the present embodiment, the baseband processing device 11 that can be used in the non-array-capable base station 200 can input the phase change information from the signal processing device 12, and its DFT processing unit By enabling 410 to adjust the position of the DFT window based on the phase change information, the baseband processing device 11 for the array-compatible base station 1 can be realized. Therefore, the array corresponding base station 1 can be easily realized.

  Further, since the baseband processing device 11 corrects the phase change that occurs in the received signal due to the DFT processing of the signal processing device 12, the baseband processing device 11 changes the phase from when it is received by the array antenna 130. A small number of received signals can be obtained. Therefore, in the baseband processing apparatus 11, the calculation accuracy of the shift amount of the reception timing of the signal from the communication terminal 2 is improved. As a result, the base station 1 can accurately control the transmission timing of the communication terminal 2.

<Modification of Embodiment 2>
In the baseband processing device 11 described above, the DFT processing unit 410 determines the position of the DFT window based on the phase change information, whereby the phase change generated in the received signal in the signal processing device 12 is corrected. That is, the DFT processing unit 410 functions as a phase change correction unit that corrects a phase change generated in the received signal by the DFT processing in the signal processing device 12.

  On the other hand, in the baseband processing apparatus 11 according to the present modification, the phase change is corrected by correcting the phase of the reception signal output from the DFT processing unit 410 based on the phase change information. The baseband processing apparatus 11 according to this modification will be described below.

  FIG. 16 is a diagram illustrating the baseband processing device 11 according to the present modification. As shown in FIG. 16, the baseband processing device 11 according to the present modification is the same as the baseband processing device 11 according to the first embodiment, but further includes a phase change correction unit 500. The phase change information according to the present modification example indicates the CP protrusion time length α in the DFT processing unit 120.

  The phase change correction unit 500 changes the phase of each reception complex signal constituting the reception complex signal sequence output from the DFT processing unit 110 based on the CP protrusion time length α indicated by the phase change information. Similarly to the baseband signal generation unit 122 of the first modification according to the first embodiment described above, the phase change correction unit 500 sets the phase of each reception complex signal and the period of the subcarrier corresponding to the reception complex signal. Let T be the counterclockwise rotation on the IQ plane by (2π × α / T) radians. Thereby, the phase change which generate | occur | produced in the received signal in the signal processing apparatus 12 is correct | amended. The reception complex signal sequence corrected by the phase change correction unit 500 is input to the reception data acquisition unit 113. The deviation amount acquisition unit 115 obtains a deviation amount of the reception timing of the signal from the communication terminal 2 based on the known phase-corrected reception complex signal output from the phase change correction unit 500.

  As described above, also in this modification, the phase change generated in the received signal by the DFT processing of the signal processing device 12 is corrected by the baseband processing device 11, so that the baseband processing device 11 receives the signal by the array antenna 130. As a result, it is possible to obtain a received signal with little phase change. Therefore, in the baseband processing apparatus 11, the calculation accuracy of the shift amount of the reception timing of the signal from the communication terminal 2 is improved. As a result, the base station 1 can accurately control the transmission timing of the communication terminal 2.

  In the baseband processing device 11 according to the present modification, the DFT of the signal processing device 12 is changed by individually changing the phase of each of the plurality of reception complex signals constituting the reception complex signal sequence based on the phase change information. The phase change generated in the received signal by the process is corrected. On the other hand, in the baseband processing device 11 shown in FIG. 13 described above, only the DFT window in the DFT processing unit 410 is adjusted based on the phase change information, and generated in the received signal by the DFT processing of the signal processing device 12. Phase change is corrected. Therefore, the phase change correction process is simplified by adjusting the DFT window in the DFT processing unit 410 as in the example of FIG.

  In this modification, all the phases of the plurality of reception complex signals included in the reception complex signal sequence output from the DFT processing unit 110 are changed based on the phase change information. Among them, the phase of only the known reception complex signal used when the shift amount acquisition unit 115 calculates the shift amount of the reception timing may be changed based on the phase change information. In this case, the known received complex signal output from the DFT processing unit 110 may be changed in the phase change correction unit 500 based on the phase change information, or the phase change correction unit 500 may be shifted without being provided. The quantity acquisition unit 115 may change the phase of the known reception complex signal output from the DFT processing unit 110 based on the phase change information. In the latter case, the deviation amount acquisition unit 115 functions as a phase change correction unit. The shift amount acquisition unit 115 shifts the reception timing of the signal from the communication terminal 2 based on the difference between the phase of the known reception complex signal whose phase is changed and the original phase of the known reception complex signal. Find the amount. Thereby, the shift amount of the reception timing of the signal from the communication terminal 2 can be obtained more accurately.

<Modification common to Embodiments 1 and 2 and their modifications>
In the above example, the signal processing device 12 and the baseband processing device 11 are housed in separate housings, but the signal processing device 12 and the baseband processing device 11 may be housed in the same housing. For example, if there is a space in which the signal processing device 12 can be placed in the casing of the baseband processing device 11 of the existing non-array-capable base station 200, the signal processing device 12 is placed in the space to Station 1 may be realized.

  Further, the wireless processing device 10, the signal processing device 12, and the baseband processing device 11 may be housed in the same casing. For example, in the existing non-array-capable base station 200, the radio processing device 10 and the baseband processing device 11 are accommodated in the same casing, and there is a space in which the signal processing apparatus 12 can be arranged in the casing. May implement the array-compatible base station 1 by arranging the signal processing device 12 in the space.

  In the above example, the case where the present invention is applied to a base station has been described. However, the present invention can also be applied to a wireless communication apparatus other than a base station.

DESCRIPTION OF SYMBOLS 1 Base station 2 Communication terminal 10 Radio processing apparatus 11 Baseband processing apparatus 12 Signal processing apparatus 13 Antenna 110,120,410 DFT processing part 115 Deviation amount acquisition part 121 Reception weight processing part 122,322 Baseband signal generation part 325 Phase change Information generator 500 Phase change corrector

Claims (8)

A plurality of radio processing devices that receive a multi-carrier signal including a CP (cyclic prefix) superimposed on a plurality of subcarriers orthogonal to each other and that are received by an antenna; A signal processing device connected to a baseband processing device for processing a received signal,
A Fourier transform processing unit that performs a Fourier transform process on each of a plurality of baseband received signals respectively output from the plurality of wireless processing devices;
To control reception directivities at a plurality of antennas respectively connected to the plurality of radio processing devices for a plurality of output signals respectively output from the Fourier transform processing unit and corresponding to the plurality of reception signals. Each of the plurality of reception weights, and a reception weight processing unit that generates a new reception signal by adding the plurality of output signals each having the plurality of reception weights set,
A baseband signal that performs an inverse Fourier transform process on the reception signal generated by the reception weight processing unit and generates and outputs a baseband reception signal to which a CP is added based on the obtained signal A generator,
The received signal output from the baseband signal generation unit is input to the baseband processing device,
The Fourier transform processing unit sets a Fourier transform window so that a received signal for one symbol is intentionally applied to a CP included therein,
The baseband signal generation unit is added with a CP so that a phase change occurring in the received signal is corrected by setting a Fourier transform window intentionally over the CP in the Fourier transform processing unit. A signal processing device that generates a received baseband signal. The signal processing device according to claim 1,
The baseband signal generation unit copies the first part of the multicarrier signal for one symbol with respect to the multicarrier signal obtained by performing an inverse Fourier transform process on the reception signal generated by the reception weight processing unit. And adding after the multi-carrier signal for one symbol, and copying and adding the last part of the multi-carrier signal for one symbol before the multi-carrier signal for one symbol. A signal processing device that generates a baseband reception signal to which a CP is added so that is corrected. The signal processing device according to claim 1,
The baseband signal generation unit is obtained by changing the phase of the reception signal generated by the reception weight processing unit to correct the phase change, and performing an inverse Fourier transform process on the corrected reception signal. A signal processing apparatus that generates a baseband reception signal to which a CP is added by adding the CP to the signal. A plurality of radio processing apparatuses that receive a multi-carrier signal including a CP (cyclic prefix) superimposed on a plurality of subcarriers orthogonal to each other and that are received by an antenna; A signal processing device connected to a baseband processing device for processing the received signal of
A Fourier transform processing unit that performs a Fourier transform process on each of a plurality of baseband received signals respectively output from the plurality of wireless processing devices;
To control reception directivities at a plurality of antennas respectively connected to the plurality of radio processing devices for a plurality of output signals respectively output from the Fourier transform processing unit and corresponding to the plurality of reception signals. Each of the plurality of reception weights, and a reception weight processing unit that generates a new reception signal by adding the plurality of output signals each having the plurality of reception weights set,
A baseband signal that performs an inverse Fourier transform process on the reception signal generated by the reception weight processing unit and generates and outputs a baseband reception signal to which a CP is added based on the obtained signal A generator,
The Fourier transform processing unit sets a Fourier transform window so that a received signal for one symbol is intentionally applied to a CP included therein,
The Fourier transform processing unit generates phase change information indicating a phase change that occurs in the received signal by setting a Fourier transform window so that the CP included in the received signal is intentionally applied to the received signal for one symbol. A phase change information generator that
The signal processing device, wherein the phase change information generated by the phase change information generation unit and the reception signal output from the baseband signal generation unit are input to the baseband processing device. A baseband processing device to which the signal processing device according to claim 4 is connected,
A baseband processing device, comprising: a correction unit that corrects the phase change generated in the reception signal output from the signal processing device based on the phase change information output from the signal processing device. The baseband processing device according to claim 5,
A Fourier transform processing unit for performing a Fourier transform process on the received signal output from the signal processing device;
The Fourier transform processing unit functions as the correction unit,
The Fourier transform processing unit corrects the phase change generated in the received signal by setting the position of a Fourier transform window set for the received signal based on the phase information. The baseband processing device according to claim 5,
A Fourier transform processing unit that performs a Fourier transform process on the received signal output from the signal processing device;
The correction unit changes the phase of a known reception signal output from the Fourier transform processing unit based on the phase change information output from the signal processing device, thereby generating the phase generated in the reception signal. To compensate for the change,
Based on the known reception signal corrected by the correction unit, obtaining a deviation amount for obtaining a deviation amount of a reception timing of a signal from a communication counterpart device with which the plurality of wireless processing devices to which the signal processing device is connected communicates And
A base further comprising: a control information generating unit that generates control information for controlling the transmission timing of the communication partner device, which is notified from the plurality of wireless processing devices to the communication partner device, based on the deviation amount; Band processing device. A signal processing device according to any one of claims 1 to 4,
A baseband processing device according to any one of claims 5 to 7,
A plurality of radio processing devices that receive a multi-carrier signal including a CP (cyclic prefix) on which a plurality of subcarriers orthogonal to each other are superimposed and that are received by an antenna are converted into a baseband received signal and output to the signal processing device A wireless communication device comprising:

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