JP5450278B2 - Communication system, receiver, transmitter - Google Patents

Description

  The present invention relates to a communication system, a receiving apparatus, and a transmitting apparatus that can communicate using a frequency band effectively.

  2. Description of the Related Art Conventionally, in wireless communication and wired communication, improvement in frequency band utilization efficiency is demanded as demand increases.

  In order to improve the utilization efficiency of the frequency band, for example, the modulated modulation signal is divided into a plurality of sub-modulation signals and transmitted, and the received plurality of sub-modulation signals are received and demodulated into the original modulation signal. Thus, a technology that uses vacant bands scattered on the frequency axis has been disclosed (see Non-Patent Document 1).

9, as an example, of a conventional a receiving apparatus 520 that receives a signal transmitted transmission apparatus 510, and the transmitting apparatus divides transmits the modulated signal to a plurality of bands, to recover the modulated signal before division A communication system 500 is shown .
As illustrated in FIG. 9, the transmission device 510 includes a modulation circuit 601, a transmission filter bank 602, and a D / A converter 603. The reception device 520 includes an A / D converter 611, a reception filter bank 612, and a demodulation circuit 613.

  The transmission filter bank 602 includes a serial-parallel conversion circuit 604, an FFT (Fast Fourier Transform) circuit 605, a division circuit 604, frequency shifters 607-1 to 607-N, an addition circuit 608, an IFFT (Fast Inverse Fourier Transform) circuit 609, a parallel A serial conversion circuit 610 is provided.

  The reception filter bank 612 includes a series-parallel circuit 614, an FFT circuit 615, an extraction circuit 614, frequency shifters 617-1 to 617-N, an adder circuit 618, an IFFT circuit 619, and a parallel-serial conversion circuit 620.

  Next, a signal flow in the communication apparatus 500 will be described. FIGS. 10A to 10C show an example of the bandwidth of the transmission apparatus 510 divided into N (N = 2) and distributed. FIGS. 10D to 10F show an example in the case where the band divided by the transmission device 519 is combined in the reception device 520.

  Transmitting apparatus 510 modulates a data signal to be transmitted by modulation circuit 601 using a modulation scheme such as QPSK, and inputs the waveform-shaped modulated signal shown in FIG. 10A to transmission filter bank 602. The output signal from the transmission filter bank 602 is converted into an analog signal by the D / A converter 603 and transmitted.

In the transmission filter bank 602, the input signal is serial-parallel converted by the serial-parallel conversion circuit 604, and fast Fourier transform is performed by the FFT circuit 605, thereby converting the time-domain signal to the frequency-domain signal. Next, the modulation signal converted into the frequency domain is multiplied by a coefficient for dividing the signal band indicated by the broken line in FIG. 10A by N by the dividing circuit 604 to generate N sub-modulated signals (FIG. 10). (B)) After that, N sub-modulated signals are distributed and arranged in a predetermined band on the frequency axis by the frequency shifters 607-1 to 607 -N, and the frequency shifters 607-1 to 6 07 -N are added by the adding circuit 608. Are added together (FIG. 10C). Finally, the IFFT circuit 609 performs fast inverse Fourier transform to convert the frequency domain signal to the time domain signal, and the parallel-serial conversion circuit 610 performs parallel-serial conversion.

  In the receiving device 520, the received signal is converted into a digital signal by the A / D converter 611 and input to the receiving filter bank 612. The demodulating circuit 613 demodulates the modulated signal output from the receiving filter bank 612 and restores the data signal. To do.

  In the reception filter bank 612, the input signal is serial-parallel converted by the serial-parallel conversion circuit 614, and fast Fourier transform is performed by the FFT circuit 115 to convert the time-domain signal to the frequency-domain signal. Next, the extraction circuit 614 multiplies the received signal converted into the frequency domain by a coefficient indicated by a broken line in FIG. 10D to extract N sub-modulated signals. Thereafter, the frequency shifters 617-1 to 617-N return the extracted sub-modulated signals to the bands before being shifted by the transmission-side frequency shifters 607-1 to 607-N (FIG. 10 (e)), and the addition. The circuit 618 adds all the sub-modulation signals to obtain a synthesized modulation signal (FIG. 10 (f)). Finally, the IFFT circuit 619 performs high-speed inverse Fourier transform to convert the frequency domain signal to the time domain signal, and the parallel-serial conversion circuit 620 performs parallel-serial conversion.

  As described above, the communication system 500 can divide the occupied band of the transmission signal and disperse the generated sub-modulated signals at arbitrary locations on the frequency axis, so that a discontinuous free frequency band can be effectively used.

Junichi Abe, Fumihiro Yamashita, Satoshi Kobayashi, Proposal of band-dispersed transmission using spectrum editing technology, Society Conference of IEICE, B-3-11, September 2009, Proceedings of Communication Lecture 1, pp.263

  However, in the conventional technique, the received sub-modulation signals are synthesized as they are without being corrected for the phase rotation gradient generated within the occupied band of the transmission signal by transmission, and demodulated into the original modulation signal. Will deteriorate.

  Here, the relationship between the inclination of the phase rotation and the signal transmission characteristics will be briefly described. In general, in a transmission line, a phase gradient occurs within the occupied band of a transmission signal. FIG. 11 shows the phase tilt in the occupied band that occurs when a single carrier signal is transmitted.

  When there is a transmission delay Δt, as shown in FIG. 11, the received signal has a phase rotation proportional to the transmission delay Δt and the frequency f, that is, a phase inclination of −2πΔt on the frequency axis. In the case of FIG. 10, the Nyquist timing can be extracted by shifting the symbol timing by Δt in the timing recovery of the received signal. Therefore, when the phase characteristic in the occupied band is a straight line, demodulation is possible without any problem.

On the other hand, as shown in FIG. 12, when the transmission band divides the occupied band of the modulation signal into a plurality of sub-modulation signals and transmits the sub-modulation signals, the phase gradient shown in FIG. As a result, when the sub-modulated signal k is shifted by Δf _k on the transmission side, phase rotation of −2πΔt × Δf _k occurs discontinuously (k is a natural number of 1 to N) as compared to the case where the frequency is not shifted. As shown in FIG. 12D, when all the sub-modulated signals are combined on the receiving side, the phase characteristics do not become a straight line within the occupied band of the combined modulated signal. In general, in order to transmit a signal without distortion, it is necessary to satisfy a distortion-free condition in which the amplitude is constant and the phase characteristic is a straight line. In the transmission of the sub-modulated signal, there is a problem that the signal transmission characteristic is deteriorated because the no-distortion condition is not satisfied.

  SUMMARY OF THE INVENTION In view of the above-described problems of the prior art, an object of the present invention is to provide a technique capable of improving signal transmission characteristics while improving the use efficiency of a frequency band in communication using a plurality of sub-modulated signals. .

  In order to solve the above problems, a communication system of the present invention is a communication system having a transmission device and a reception device, and the transmission device includes a dividing unit that divides an input signal to be transmitted into a plurality of band components, The receiving device includes a transmission signal generation unit that generates a transmission signal by distributing a plurality of band components of the input signal on the frequency axis, and a transmission unit that transmits the transmission signal, and the reception device receives the transmission signal. And an extraction unit that extracts a plurality of band components of the input signal from the received transmission signal, and the transmission delay in the transmission signal is corrected and corrected so that the phase characteristics between the extracted band components are flat. A phase compensation unit that outputs the transmission signal to the extraction unit; and a restoration unit that synthesizes a plurality of band components to restore the input signal.

  Further, the transmission device includes a reference signal generation unit that generates a plurality of reference signals having different frequencies, which are used for correcting transmission delay caused by transmission of the input signal, and the transmission signal generation unit includes a plurality of band components of the input signal. A plurality of reference signals are distributed on the frequency axis to generate a transmission signal, and the extraction unit extracts a plurality of reference signals together with a plurality of band components of the input signal from the received transmission signal, and a phase compensation unit May calculate a difference in rotation amount of phase rotation between the extracted reference signals, correct a transmission delay in the transmission signal based on the difference in rotation amount, and output the corrected transmission signal to the extraction unit .

  Further, the transmission device includes a reference signal generation unit that generates a plurality of reference signals having different frequencies, which are used for correcting transmission delay caused by transmission of the input signal, and the transmission signal generation unit includes a plurality of band components of the input signal. Are distributed on the frequency axis to generate a first transmission signal, a plurality of reference signals are distributed on the frequency axis to generate a second transmission signal, and the transmission unit includes a second transmission signal along with the first transmission signal. The transmission unit transmits a transmission signal, the reception unit receives a second transmission signal together with the first transmission signal, and the extraction unit includes a plurality of band components of the input signal from the received first transmission signal and a plurality of band signals from the second transmission signal. The reference signal is extracted, and the phase compensation unit calculates a difference in rotation amount of the phase rotation between the extracted reference signals, and calculates a transmission delay in the first transmission signal and the second transmission signal based on the difference in rotation amount. Corrected, corrected second Transmission signal and the second transmit signal may be output to the extraction unit.

  The phase compensation unit further includes a sampling unit that samples the received transmission signal and outputs the sampled signal to the extraction unit. The phase compensation unit performs sampling of the sampling unit so that the difference in rotation amount between the reference signals becomes zero. The transmission delay may be corrected by adjusting the interval.

  In addition, the phase compensation unit further includes a signal delay unit that delays the received transmission signal and outputs the delayed transmission signal to the extraction unit, and the phase compensation unit includes a signal delay unit so that the difference in rotation amount between the reference signals becomes zero. The transmission delay may be corrected by adjusting the delay amount with respect to the transmission signal.

  The phase compensation unit further includes a sampling unit that samples the received first transmission signal and the second transmission signal and outputs them to the extraction unit, and the phase compensation unit has a difference in rotation amount between the reference signals of 0. As described above, the transmission delay may be corrected by adjusting the sampling interval of the sampling unit.

  The phase compensation unit further includes a signal delay unit that delays the received first transmission signal and the second transmission signal and outputs the delayed signals to the extraction unit, and the phase compensation unit sets the difference in rotation amount between the reference signals to zero. As described above, the transmission delay may be corrected by adjusting the delay amount of the signal delay unit with respect to the first transmission signal and the second transmission signal.

  The transmission signal generation unit further includes a frequency shift unit that shifts each of the plurality of band components of the input signal by a shift amount corresponding to the center frequency of each band component, and the transmission signal generation unit shifts each shift component by the shift amount. The band component may be arranged on the frequency axis.

  The receiving apparatus of the present invention receives a transmission signal in which a plurality of band components obtained by dividing an input signal to be transmitted and a plurality of reference signals having different frequencies used for correcting transmission delay caused by transmission are distributed on the frequency axis. A receiving unit, an extracting unit for extracting a plurality of band components of the input signal and a plurality of reference signals from the received transmission signal, and calculating a difference in rotation amount of the phase rotation between the extracted reference signals. A phase compensation unit that corrects a transmission delay in the transmission signal based on the difference and outputs the corrected transmission signal to the extraction unit, and a restoration unit that combines the plurality of band components to restore the input signal.

  The receiving apparatus of the present invention includes a first transmission signal in which a plurality of band components obtained by dividing an input signal to be transmitted are distributed on the frequency axis, and a plurality of reference signals used for correcting transmission delay caused by transmission on the frequency axis. A receiving unit that receives the second transmission signal distributed in a distributed manner, an extracting unit that extracts a plurality of band components of the input signal and a plurality of reference signals from the received first transmission signal and the second transmission signal, A difference in rotation amount of phase rotation between the reference signals is calculated, a transmission delay in the first transmission signal and the second transmission signal is corrected based on the difference in rotation amount, and the corrected first transmission signal and second transmission signal are corrected. Are provided to the extraction unit, and a restoration unit that combines the plurality of band components to restore the input signal.

  The phase compensation unit further includes a sampling unit that samples the received transmission signal and outputs the sampled signal to the extraction unit. The phase compensation unit performs sampling of the sampling unit so that the difference in rotation amount between the reference signals becomes zero. The transmission delay may be corrected by adjusting the interval.

  In addition, the phase compensation unit further includes a signal delay unit that delays the received transmission signal and outputs the delayed transmission signal to the extraction unit, and the phase compensation unit includes a signal delay unit so that the difference in rotation amount between the reference signals becomes zero. The transmission delay may be corrected by adjusting the delay amount with respect to the transmission signal.

  The phase compensation unit further includes a sampling unit that samples the received first transmission signal and the second transmission signal and outputs them to the extraction unit, and the phase compensation unit has a difference in rotation amount between the reference signals of 0. As described above, the transmission delay may be corrected by adjusting the sampling interval of the sampling unit.

  The phase compensation unit further includes a signal delay unit that delays the received first transmission signal and the second transmission signal and outputs the delayed signals to the extraction unit, and the phase compensation unit sets the difference in rotation amount between the reference signals to zero. As described above, the transmission delay may be corrected by adjusting the delay amount of the signal delay unit with respect to the first transmission signal and the second transmission signal.

The transmitting apparatus of the present invention includes a dividing unit that divides an input signal to be transmitted into a plurality of band components, and a plurality of different frequencies used for correcting transmission delay caused by transmission of the input signal in the receiving apparatus that receives the input signal. A reference signal generator for generating a reference signal, a transmission signal generator for generating a transmission signal by distributing a plurality of band components of the input signal and a plurality of reference signals on the frequency axis, and transmission for transmitting the transmission signal The transmission signal generation unit further includes a frequency shift unit that shifts each of the plurality of band components of the input signal by a shift amount corresponding to the center frequency of each band component, and the transmission signal generation unit shifts It puts each band components shifted by an amount on the frequency axis.

The transmitting apparatus of the present invention includes a dividing unit that divides an input signal to be transmitted into a plurality of band components, and a plurality of different frequencies used for correcting transmission delay caused by transmission of the input signal in the receiving apparatus that receives the input signal A reference signal generator for generating a reference signal, and a plurality of band components of the input signal are distributed on the frequency axis to generate a first transmission signal, and a plurality of reference signals are distributed on the frequency axis. A transmission signal generation unit that generates a second transmission signal; and a transmission unit that transmits the first transmission signal and the second transmission signal . The transmission signal generation unit converts each of the plurality of band components of the input signal to each band component. further comprising a frequency shifter for frequency shifting by the shift amount corresponding to the center frequency of the transmission signal generating section, place each band components shifted by the shift amount on the frequency axis.

  According to the present invention, it is possible to improve signal transmission characteristics while improving utilization efficiency of a frequency band in communication using a plurality of sub-modulated signals.

1 is a block diagram showing a configuration of a communication system 100 according to an embodiment of the present invention. The figure which shows an example of the processing operation with respect to the modulation signal by the transmitter 110 The figure which shows an example of the processing operation with respect to the received signal by the receiver 120 The block diagram which shows the structure of the communication system 200 which concerns on the modification of one Embodiment. The block diagram which shows the structure of the communication system 300 which concerns on other embodiment of this invention. The figure which shows an example of the time multiplex processing operation | movement by the selector 40 of the transmitter 310. The figure which shows the other example of dispersion | distribution arrangement | positioning of N submodulation signals and pilot signals The block diagram which shows the other structural example of the communication system 300 which concerns on other embodiment. A block diagram showing a configuration example of a conventional communication system 500 FIG. 2 is a block diagram showing an example of processing operation for a modulated signal by a conventional communication system 500. The figure which shows an example of the change of the phase characteristic in the occupation band in transmission of the conventional single carrier signal The figure which shows an example of the change of the phase characteristic in the occupied band by transmission of the conventional N submodulation signal

<< One Embodiment >>
FIG. 1 is a block diagram showing a configuration of a communication system 100 according to an embodiment of the present invention. The communication system 100 according to the present embodiment includes a transmission device 110 and a reception device 120. FIG. 1 shows only the main part of the communication system 100 of the present embodiment. For example, a control unit that performs overall control of each unit of the communication system 100, an input unit that inputs an input signal of data to be transmitted in the transmission device 110, a transmission unit that transmits data, a reception unit that receives data in the reception device 120, and its data The output part etc. which output are abbreviate | omitted.

  The transmission apparatus 110 includes a modulation circuit 1, a transmission filter bank 2, a D / A converter 3, and a pilot signal generation circuit 4. The transmission filter bank 2 includes a serial-parallel conversion circuit 5, an FFT circuit 6, a dividing circuit 7, frequency shifters 8-1 to 8-N, an adder circuit 9, an IFFT circuit 10, and a parallel-serial conversion circuit 11, and a transmission signal generation unit Works as.

  The modulation circuit 1 modulates an input signal of data to be transmitted input from an input unit (not shown) by a modulation method such as quadrature phase shift keying (QPSK). The modulation circuit 1 outputs the modulated modulation signal to a serial / parallel conversion circuit 5 including a multiplexer (MUX). The serial / parallel conversion circuit 5 performs serial / parallel conversion on the modulated signal and outputs the result to the FFT circuit 6.

The FFT circuit 6 performs a known fast Fourier transform on the modulation signal to convert from a time domain signal to a frequency domain signal (FIG. 2A).
The dividing circuit 7 generates N sub-modulated signals for the modulated signal converted into the frequency domain (FIG. 2B). Specifically, for example, the dividing circuit 7 includes N filters having different pass bands, and by multiplying the modulation signal by a coefficient corresponding to the pass band of each filter (broken line in FIG. 2A), N sub-modulated signals are generated. The dividing circuit 7 outputs the divided N sub-modulated signals to the frequency shifters 8-1 to 8-N according to the frequency band of the sub-modulated signal. FIG. 2 shows the processing operation for the modulation signal when N = 2, but the same processing is performed when N> 2.

Frequency shifters 8-1 to 8-N disperse and arrange each of the sub-modulated signals in a desired band on the frequency axis. That is, the frequency shifters 8-1 to 8-N shift the sub-modulated signals by the shift amount α _N so as not to overlap each other. The shift amount α _N is determined by the interval between the center frequency f ₀ of the modulation signal and the center frequency f _N of each sub modulation signal, the bandwidth of the modulation signal and sub modulation signal, the number N of sub modulation signals, and the like. It is preferred that Alternatively, in FIG. 2C, as an example in the case of N = 2, each frequency shifter 8 shifts the sub-modulation signal away from the center frequency f ₀ of the modulation signal. shift alpha _N and the shift direction of each sub-modulation signal can be set arbitrarily.

  As shown in FIG. 2 (d), the adder circuit 9 is different in that the N sub-modulated signals frequency-shifted by the frequency shifters 8-1 to 8-N and the frequency output from the pilot signal generating circuit 4 are different from each other. One pilot signal is distributed and arranged in a band where FFT points are present so as not to be superposed on N sub-modulated signals. The adder circuit 9 outputs the frequency-multiplexed signal to the IFFT circuit 10.

  As will be described later, the pilot signal generation circuit 4 is a reference signal generation unit that generates and outputs two pilot signals of unmodulated signals having different frequencies Δf as reference signals used for correction of transmission delay. The magnitude of Δf is 10 kHz or the like, and is preferably set based on the communication method and the size of the free band.

  The IFFT circuit 10 performs fast inverse Fourier transform (IFFT) on a signal in which N sub-modulated signals and two pilot signals are dispersedly arranged on the frequency axis by the adder circuit 9 to convert the frequency domain signal into a time domain signal. Convert.

  The parallel-serial conversion circuit 11 includes a demultiplexer (DEMUX) and the like, and performs parallel-serial conversion on the output signal of the IFFT circuit 10.

  The D / A converter 3 converts the signal from a digital signal to an analog signal. The transmission unit (not shown) transmits the converted analog signal as a transmission signal to another communication system 100.

  On the other hand, the reception device 120 includes an A / D converter 12, a resampler 13, a reception filter bank 14, and a demodulation circuit 15. The reception filter bank 14 includes a serial-parallel conversion circuit 16, an FFT circuit 17, an extraction circuit 18, a sample clock adjuster 19, a frequency shifter 23-1 to 23-N, an addition circuit 24, an IFFT circuit 25, and a parallel-serial conversion circuit. 26 and operates as a restoration unit. The sample clock adjuster 19 includes a phase tilt estimation circuit 20, a loop filter 21, and an NCO 22. The NCO 22 is a numerically controlled oscillator, and outputs a signal having a frequency corresponding to the input numerical value by inputting the numerical value indicating the frequency.

  The A / D converter 12 converts a transmission signal transmitted from a transmission device 110 of another communication system 100 received by a reception unit (not shown) into a digital signal reception signal.

  The resampler 13 adjusts the sampling interval based on a sample clock control signal from a sample clock adjuster 19 described later. Thereby, the resampler 13 can sample while correcting the transmission delay caused by the transmission. The resampler 13 outputs the sampled reception signal to the reception filter bank 14.

  The serial-parallel conversion circuit 16 performs serial-parallel conversion on the received signal, and the FFT circuit 17 performs a known fast Fourier transform on the received signal subjected to serial-parallel conversion, and converts the received signal from a time domain signal to a frequency domain signal. Conversion is performed (FIG. 3A). The FFT circuit 17 outputs the received signal shown in FIG.

  The extraction circuit 18 extracts N submodulation signals and two pilot signals from the reception signal converted into the frequency domain. Specifically, for example, the extraction circuit 18 includes N filters having different pass bands, and multiplies the spectrum of the received signal by a coefficient corresponding to the pass band of each filter (broken line in FIG. 3A). Thus, N sub-modulated signals and two pilot signals are extracted. The extraction circuit 18 outputs the extracted N sub-modulated signals to the frequency shifters 23-1 to 23-N according to the frequency band of each sub-modulated signal. On the other hand, the extraction circuit 18 outputs two pilot signals to the sample clock adjuster 19.

  The phase tilt estimation circuit 20 of the sample clock adjuster 19 calculates the rotation amount θ of the phase rotation generated by transmission from each of the two pilot signals extracted by the extraction circuit 18. The phase inclination estimation circuit 20 calculates a phase inclination estimation value β that is a phase rotation inclination Δθ / Δf based on the difference Δθ between the phase rotation amounts of the two pilot signals and the frequency interval Δf.

  The loop filter 21 of the sample clock adjuster 19 suppresses the instantaneous fluctuation of the phase tilt estimation value β output from the phase tilt estimation circuit 20 and outputs it to the NCO 22. The NCO 22 generates a sample clock control signal based on the phase tilt estimated value β output from the loop filter 21 and outputs the sample clock control signal to the resampler 13. Based on the sample clock control signal, the resampler 13 adjusts the sampling interval so that the phase rotation inclination Δθ / Δf becomes 0 (transmission delay Δt is 0), samples the received signal, A reception signal in which the phase characteristics of the sub-modulation signals are flattened is output. Then, the transmission delay Δt is corrected by the resampler 13 in front of the FFT circuit 17, so that the FFT circuit 17 can suppress the occurrence of the phase rotation gradient Δθ / Δf.

  That is, the occurrence of the phase inclination is caused by the shift of the fast Fourier transform timing between the transmitting and receiving stations due to the transmission delay Δt. The fast Fourier transform is repeatedly executed at a time period corresponding to the number of points of the fast Fourier transform. For example, in the case of 1024 points, it is executed every 1024 sample timings. Therefore, if the sample timing of the received signal is adjusted before the fast Fourier transform, the occurrence of phase tilt can be suppressed. That is, in the present embodiment, the resampler 13, the serial / parallel conversion circuit 16, the FFT circuit 17, the extraction circuit 18, and the sample clock adjuster 19 operate as the phase compensation unit 27.

  The phase compensator 27 obtains the phase inclination estimation value β of the phase rotation inclination Δθ / Δf from the pilot signal in the phase inclination estimation circuit 20, and the NCO 22 sets the transmission delay Δt to 0 based on the phase inclination estimation value β. Thus, the sample clock control signal is output to the resampler 13. That is, since the phase compensation unit 27 operates as a feedback circuit, the phase rotation gradient Δθ / Δf gradually becomes zero. As a result, as shown in FIG. 3B, the received modulated signal after the synthesis satisfies the no distortion condition.

  The frequency shifters 23-1 to 23-N return N sub-modulated signals to a band before being frequency-shifted by the frequency shifters 8-1 to 8-N, for example, as shown in FIG. .

  The adder circuit 24 adds all the sub-modulated signals and outputs a synthesized modulated signal (FIGS. 2A and 3B).

  The IFFT circuit 25 performs a known fast inverse Fourier transform on the modulated signal, and outputs a modulated signal converted from a frequency domain signal to a time domain signal.

  The parallel / serial conversion circuit 26 performs parallel / serial conversion on the modulated signal, and restores and outputs the modulated signal transmitted by the transmission device 110. The demodulation circuit 15 demodulates the modulation signal and outputs the received data.

As described above, in the present embodiment, when transmitting apparatus 110 decomposes a modulated signal into N sub-modulated signals and transmits them to receiving apparatus 120, a plurality of pilot signals are frequency-multiplexed and transmitted. By correcting the transmission delay Δt caused by the transmission, it is possible to receive a modulated signal that satisfies the non-distortion condition while improving the effective use of the frequency band, and to improve the signal transmission characteristics.
<< Modification of one embodiment >>
FIG. 4 is a block diagram showing a configuration of a communication system 200 according to a modification of one embodiment of the present invention. The communication system 200 according to the present embodiment includes a transmission device 210 and a reception device 220.

  Note that in the communication system 200 of the present embodiment, the same components as those of the communication system 100 of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The communication system 200 of the present embodiment is different from the communication system 100 of the first embodiment in that the phase compensation unit 27 of the reception device 220 includes the variable delay device 31, the serial-parallel conversion circuit 16, the FFT circuit 17, the extraction circuit 18, A timing adjuster 30 is provided, and the timing adjuster 30 is provided with a phase tilt estimation circuit 20 and a loop filter 21.

  The timing adjuster 30 calculates the rotation amount θ of the phase rotation generated by the transmission from each of the two pilot signals extracted by the extraction circuit 18 in the phase tilt estimation circuit 20. The phase inclination estimation circuit 20 calculates a phase inclination estimation value β that is a phase rotation inclination Δθ / Δf based on the difference Δθ between the phase rotation amounts of the two pilot signals and the frequency interval Δf. In consideration of the periodicity of the conversion timing of the fast Fourier transform by the FFT circuit 17, the phase tilt estimation circuit 20 has a phase rotation tilt Δθ / Δf of 0 (transmission delay Δt = 0) based on the phase tilt estimation value β. Thus, the delay amount in the variable delay device 31 is calculated and output.

  The loop filter 21 suppresses instantaneous fluctuations in the output value of the phase tilt estimation circuit 20 and outputs the delay amount to the variable delay device 31 as a delay amount control signal.

  The variable delay device 31 sets a delay amount for the received signal based on the delay amount control signal, and outputs the received signal with the transmission delay Δt corrected to the FFT circuit 17.

  For example, if the number of FFT points in the FFT circuit 17 is m, m−Δt / m due to the transmission delay Δt. Therefore, the variable delay device 31 can correct the FFT point to m by setting the delay amount and delaying the reception signal based on the delay amount control signal. For example, when the FFT circuit 17 uses 2048-point FFT, if a transmission delay of 1536 samples occurs, the transmission delay can be corrected by adding a delay of 512 samples. In this way, the variable delay device 31 can suppress the occurrence of the phase rotation gradient Δθ / Δf by adjusting the delay amount of the received signal in the previous stage of the FFT circuit 17, as shown in FIG. Thus, the received modulated signal after synthesis satisfies the no distortion condition.

  Note that the operation of the communication system 200 of the present embodiment is the same as that of the communication system 100 of the first embodiment, and a detailed description thereof is omitted.

As described above, in the present embodiment, when the transmitting apparatus 210 decomposes the modulated signal into N sub-modulated signals and transmits them to the receiving apparatus 220, a plurality of pilot signals are frequency-multiplexed and transmitted. By correcting the transmission delay Δt caused by the transmission, it is possible to receive a modulated signal that satisfies the non-distortion condition while improving the effective use of the frequency band, and to improve the signal transmission characteristics.
<< Other embodiments >>
FIG. 5 is a block diagram showing a configuration of a communication system 300 according to another embodiment of the present invention. The communication system 300 according to the present embodiment includes a transmission device 310 and a reception device 320.

  In the communication system 300 according to the present embodiment, the same components as those of the communication system 100 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

The communication system 300 of the present embodiment is different from the communication system 100 of the first embodiment as follows.
1) The transmission device 310 includes the selector 40, and the reception device 320 includes the selector 50.
2) The dividing circuit 7 ′ performs the same operation as the dividing circuit 7 of the communication system 100 according to the embodiment, but outputs N sub-modulated signals obtained by dividing the modulated signal to the selector 40.
3) The extraction circuit 18 ′ outputs the extracted N sub-modulated signals and the two pilot signals to the selector 50.
4) The pilot signal generation circuit 4 ′ generates two pilot signals having different frequencies Δf and outputs them to the selector 40.
5) The adder circuit 9 ′ adds the N sub-modulated signals and the two pilot signals individually and distributes them on the frequency axis according to the operation of the selector 40 described later.

  The selector 40 of this embodiment performs a switching operation based on a control signal from a control unit that performs overall control of the communication system 300 (not shown), and converts the N sub-modulation signals and the two pilot signals into the frequency shifter 8- Output to 1-8-N. As a result, the adder circuit 9 'adds the N sub-modulated signals and the two pilot signals individually and distributes them on the frequency axis, as shown in FIG. That is, the transmission filter bank 2 includes a transmission signal (first transmission signal) in which N sub-modulated signals are distributed on the frequency axis, and a transmission signal (first transmission signal) in which two pilot signals are distributed on the frequency axis. 2 transmission signals) are generated and transmitted to another communication system 300.

  FIG. 6 shows the case where N = 2, but the same applies to the case where N> 2. Further, when the selector 40 selects two pilot signals, each of the frequency shifters 8-1 to 8-N operates so as to pass through these pilot signals without performing anything or to arrange them in a desired band. It is preferable to make it.

  As in the case of the selector 40, the selector 50 performs a switching operation based on a control signal from a control unit (not shown), and each of the N sub-modulated signals extracted from the first transmission signal received by the extraction circuit 18 is obtained. Output to the frequency shifters 23-1 to 23 -N, and output two pilot signals extracted from the second transmission signal to the phase compensator 27.

  In this embodiment, for example, a control unit (not shown) synchronizes between the transmission device 310 and the reception device 320 prior to communication, and based on the synchronization, the control unit (not shown) causes the selector 40 to , 50, it is preferable to generate and output a control signal for selecting N sub-modulated signals and two pilot signals.

  The operation of the communication system 300 of this embodiment is the same as that of the communication system 100 of the first embodiment, and a detailed description thereof is omitted.

As described above, in the present embodiment, when transmitting apparatus 310 decomposes a modulated signal into N sub-modulated signals and transmits them to receiving apparatus 320, a plurality of pilot signals are time-multiplexed and transmitted. By correcting the transmission delay Δt caused by the transmission, it is possible to receive a modulated signal that satisfies the non-distortion condition while improving the effective use of the frequency band, and to improve the signal transmission characteristics.
<< Additional items of embodiment >>
The present invention can be applied not only to wireless communication in satellite communication and terrestrial wireless networks, but also to communication on wired lines.

  Further, in the present invention, it is preferable that the transmission filter bank 2 and the reception filter bank 14 are configured to use overlap addition or overlap storage.

  In another embodiment of the present invention, in the configuration of the phase compensation unit 27 of the receiving device 320, the resampler 13 and the sample clock adjuster 19 are modified in the embodiment as shown in FIG. Similarly to the above, the communication system 400 may be replaced with the variable delay device 31 and the timing adjuster 30.

  Furthermore, in the present invention, the transmission devices 110, 210, 310, and 410 and the reception devices 120, 220, 320, and 420 can be appropriately selected and combined according to the communication method.

  In the above embodiment, the pilot signal generation circuits 4 and 4 ′ generate two pilot signals having different frequencies. However, the present invention is not limited to this, and generates three or more pilot signals having different frequencies. Also good.

  In the above embodiment, the pilot signal is an unmodulated signal. However, the present invention is not limited to this. For example, a signal modulated by a predetermined pattern may be used as the pilot signal.

  In the above embodiment, as shown in FIG. 2D, the two pilot signals are arranged in a frequency band different from the frequency band in which the N sub-modulated signals are distributed, but the present invention is not limited to this. . For example, as shown in FIG. 7A, two pilot signals may be arranged at both ends of one sub modulation signal. This is preferable from the viewpoint of effective use of the frequency band because it is not necessary to prepare a special band for the pilot signal.

  Further, as shown in FIG. 7B, pilot signals may be arranged at both ends of each sub-modulation signal. As a result, the phase inclination estimation circuit 20 can calculate the phase rotation inclination Δθ / Δf calculated from these pilot signals and improve the leveling accuracy.

  In the embodiment described above, the measurement of the rotation amount θ of the phase rotation is performed in parallel with the transmission of N sub-modulated signals, but the present invention is not limited to this. For example, at the start of communication, the control unit (not shown) may transmit a plurality of pilot signals, and the phase inclination estimation circuit 20 may calculate the phase inclination estimation value β with a predetermined synchronization during communication. . In another embodiment, for example, the control unit (not shown) may switch the selectors 40 and 50 to the sub-modulation signal transmission mode when the calculation is completed. Note that the switching timing is preferably set to a predetermined time.

  In the above embodiment, N sub-modulated signals and two pilot signals are frequency-multiplexed or time-multiplexed. However, the present invention is not limited to this, and a multiplexing scheme such as code spread multiplexing may be used.

  From the above detailed description, features and advantages of the embodiment will become apparent. It is intended that the scope of the claims extend to the features and advantages of the embodiments described above without departing from the spirit and scope of the right. Further, any person having ordinary knowledge in the technical field should be able to easily come up with any improvements and changes, and there is no intention to limit the scope of the embodiments having the invention to those described above. It is also possible to use appropriate improvements and equivalents within the scope disclosed in.

DESCRIPTION OF SYMBOLS 1 Modulation circuit, 2 Transmission filter bank, 3 D / A converter, 4 Pilot signal generation circuit 4, 5, 16 Serial / parallel conversion circuit, 6, 17 FFT circuit, 7, 7 'Dividing circuit, 8-1-8- N, 23-1 to 23-N Frequency shifter, 9, 9'24 adder circuit, 10, 25 IFFT circuit, 11 parallel-serial converter circuit, 12 A / D converter, 13 resampler, 14 reception filter bank, 15 modulation circuit , 18, 18 ′ extraction circuit, 19 sample clock adjuster, 20 phase slope estimation circuit, 21 loop filter, 22 NCO, 30 timing adjuster, 31 variable delay device, 40, 50 selector, 100, 200, 300, 400 communication System, 110, 210, 310, 410 Transmitter, 120, 220, 320, 420 Receiver

Claims (16)

A communication system having a transmitter and a receiver,
The transmitter is
A dividing unit that divides the input signal to be transmitted into a plurality of band components;
A transmission signal generation unit that generates a transmission signal by distributing and arranging the plurality of band components of the input signal on a frequency axis;
A transmission unit for transmitting the transmission signal,
The receiving device is:
A receiver for receiving the transmission signal;
An extraction unit that extracts a plurality of band components of the input signal from the received transmission signal;
As the extraction phase characteristics between the plurality of band components is Hira担, a phase compensation unit for the transmission delay is corrected that put the transmission signal, and outputs the transmission signal corrected to the extractor,
A restoration unit that combines the plurality of band components to restore the input signal. The communication system according to claim 1, wherein
The transmitter is
A reference signal generation unit that generates a plurality of reference signals having different frequencies, which are used to correct transmission delay caused by transmission of the input signal;
The transmission signal generation unit generates the transmission signal by distributing and arranging the plurality of reference signals on the frequency axis together with the plurality of band components of the input signal,
The extraction unit extracts the plurality of reference signals together with a plurality of band components of the input signal from the received transmission signal,
The phase compensation unit calculates a difference in rotation amount of phase rotation between the extracted reference signals, corrects the transmission delay in the transmission signal based on the difference in rotation amount, and corrects the transmission signal Is output to the extraction unit. The communication system according to claim 1, wherein
The transmitter is
A reference signal generation unit that generates a plurality of reference signals having different frequencies, which are used to correct transmission delay caused by transmission of the input signal;
The transmission signal generation unit generates the first transmission signal by distributing the plurality of band components of the input signal on the frequency axis and secondly distributing the plurality of reference signals on the frequency axis. Generate a transmission signal,
The transmitter transmits the second transmission signal together with the first transmission signal;
The receiving unit receives a second transmission signal together with the first transmission signal;
The extraction unit extracts the plurality of reference signals from the second transmission signal together with the plurality of band components of the input signal from the received first transmission signal,
The phase compensation unit calculates a difference in rotation amount of phase rotation between the extracted reference signals, and corrects the transmission delay in the first transmission signal and the second transmission signal based on the difference in rotation amount. Then, the corrected first transmission signal and second transmission signal are output to the extraction unit. The communication system according to claim 2,
The phase compensation unit includes:
A sampling unit that samples the received transmission signal and outputs the sampled signal to the extraction unit;
The communication system, wherein the phase compensation unit corrects the transmission delay by adjusting the sampling interval of the sampling unit so that a difference in rotation amount between the reference signals becomes zero. The communication system according to claim 2,
The phase compensation unit includes:
A signal delay unit that delays the received transmission signal and outputs the delayed signal to the extraction unit;
The phase compensation unit corrects the transmission delay by adjusting a delay amount with respect to the transmission signal of the signal delay unit so that a difference in rotation amount between the reference signals becomes zero. system. The communication system according to claim 3,
The phase compensation unit includes:
A sampling unit that samples the received first transmission signal and the second transmission signal and outputs them to the extraction unit;
The communication system, wherein the phase compensation unit corrects the transmission delay by adjusting the sampling interval of the sampling unit so that a difference in rotation amount between the reference signals becomes zero. The communication system according to claim 3,
The phase compensation unit includes:
A signal delay unit that delays the received first transmission signal and the second transmission signal and outputs the delayed signal to the extraction unit;
The phase compensation unit corrects the transmission delay by adjusting a delay amount of the signal delay unit with respect to the first transmission signal and the second transmission signal so that a difference in rotation amount between the reference signals becomes zero. A communication system characterized by: The communication system according to any one of claims 1 to 7,
The transmission signal generator is
A frequency shift unit that shifts each of the plurality of band components of the input signal by a shift amount corresponding to a center frequency of each band component;
The transmission signal generation unit arranges each band component shifted by the shift amount on the frequency axis. A receiving unit that receives a transmission signal in which a plurality of band components obtained by dividing an input signal to be transmitted and a plurality of reference signals having different frequencies used for correction of transmission delay caused by transmission are distributed on the frequency axis;
An extraction unit for extracting the plurality of band components of the input signal and the plurality of reference signals from the received transmission signal;
A difference in phase rotation amount between the extracted reference signals is calculated, the transmission delay in the transmission signal is corrected based on the difference in rotation amount, and the corrected transmission signal is output to the extraction unit. A phase compensator to perform,
A restoration unit that synthesizes the plurality of band components to restore the input signal;
A receiving apparatus comprising: A first transmission signal in which a plurality of band components obtained by dividing an input signal to be transmitted are distributed on the frequency axis, and a second transmission in which a plurality of reference signals used for correcting transmission delay caused by transmission are distributed on the frequency axis. A receiver for receiving the signal;
An extraction unit that extracts the plurality of band components and the plurality of reference signals of the input signal from the received first transmission signal and the second transmission signal;
A difference in rotation amount of phase rotation between the extracted reference signals is calculated, the transmission delay in the first transmission signal and the second transmission signal is corrected based on the difference in rotation amount, and the corrected first A phase compensator for outputting one transmission signal and a second transmission signal to the extraction unit;
A restoration unit that synthesizes the plurality of band components to restore the input signal;
A receiving apparatus comprising: The receiving device according to claim 9, wherein
The phase compensation unit includes:
A sampling unit that samples the received transmission signal and outputs the sampled signal to the extraction unit;
The phase compensation unit corrects the transmission delay by adjusting the sampling interval of the sampling unit so that a difference in rotation amount between the reference signals becomes zero. The receiving device according to claim 9, wherein
The phase compensation unit includes:
A signal delay unit that delays the received transmission signal and outputs the delayed signal to the extraction unit;
The phase compensator corrects the transmission delay by adjusting a delay amount of the signal delay unit with respect to the transmission signal so that a difference in rotation amount between the reference signals becomes zero. apparatus. The receiving device according to claim 10, wherein
The phase compensation unit includes:
A sampling unit that samples the received first transmission signal and the second transmission signal and outputs them to the extraction unit;
The phase compensation unit corrects the transmission delay by adjusting the sampling interval of the sampling unit so that a difference in rotation amount between the reference signals becomes zero. The receiving device according to claim 10, wherein
The phase compensation unit includes:
A signal delay unit that delays the received first transmission signal and the second transmission signal and outputs the delayed signal to the extraction unit;
The phase compensation unit corrects the transmission delay by adjusting a delay amount of the signal delay unit with respect to the first transmission signal and the second transmission signal so that a difference in rotation amount between the reference signals becomes zero. A receiving device. A dividing unit that divides the input signal to be transmitted into a plurality of band components;
A reference signal generation unit that generates a plurality of reference signals having different frequencies, which are used for correction of transmission delay caused by transmission of the input signal in the receiving device that receives the input signal;
A transmission signal generation unit that generates a transmission signal by distributing and arranging the plurality of band components of the input signal and the plurality of reference signals on a frequency axis;
A transmitter for transmitting the transmission signal;
Equipped with a,
The transmission signal generator is
A frequency shift unit that shifts the frequency of each of the plurality of band components of the input signal by a shift amount corresponding to the center frequency of each band component;
The transmission signal generation unit arranges each band component shifted by the shift amount on the frequency axis.
Transmission device comprising a call. A dividing unit that divides the input signal to be transmitted into a plurality of band components;
A reference signal generation unit that generates a plurality of reference signals having different frequencies, which are used for correction of transmission delay caused by transmission of the input signal in the receiving device that receives the input signal;
A transmission signal for generating a first transmission signal by distributing the plurality of band components of the input signal on the frequency axis and generating a second transmission signal by distributing the plurality of reference signals on the frequency axis A generator,
A transmission unit for transmitting the first transmission signal and the second transmission signal;
Equipped with a,
The transmission signal generator is
A frequency shift unit that shifts the frequency of each of the plurality of band components of the input signal by a shift amount corresponding to the center frequency of each band component;
The transmission signal generation unit arranges each band component shifted by the shift amount on the frequency axis.
Transmission device comprising a call.

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