JP4940216B2 - Signal receiving apparatus, signal receiving system, and signal receiving method - Google Patents

Description

  The present invention relates to a signal receiving apparatus, a signal receiving system, and a signal receiving method for a single carrier signal.

Conventionally, in a wireless transmission device in a communication system using a single carrier, a signal is communicated using a wideband signal in one channel (see, for example, Non-Patent Document 1).
D. Falconer, SL Ariyavisitakul, A. Benyamin-Seeyar, and B. Eidson, “Frequency domain equalization for single-carrier broadband wirelesssystems,” IEEE Commun. Mag., Vol. 40, no. 4, pp. 58-66, Apr. 2002.

  In recent years, it has been studied to use a single carrier in broadband transmission such as optical communication. However, since the conventional technique modulates a broadband signal as it is, the processing speed of the modulation circuit, inverse Fourier transform, GI (guard interval) insertion circuit, and operation of the D / A (digital / analog) converter / frequency conversion circuit The data rate was limited by the speed, and higher speed processing could not be performed in real time. Therefore, it is conceivable to divide the transmission band and generate a modulated signal by dividing it into a plurality of channels. However, in such a method, after frequency conversion, interference with other channels occurs, and transmission quality deteriorates. I will invite you. Further, in order to avoid interference, it is necessary to sufficiently separate the channel frequency intervals, and the frequency utilization efficiency is lowered.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a signal receiving apparatus, a signal receiving system, and a signal receiving method capable of receiving real-time and high-quality broadband transmission using a single carrier. I will provide a.

The present invention has been made to solve the above-described problems, and the invention according to claim 1 is a signal receiving apparatus that receives and demodulates an optical single carrier signal including a transmission signal, and the optical single carrier The signal transmission device converts the transmission data into parallel data, modulates each of the parallel-converted transmission data, performs Fourier transformation, and inserts a frequency component of 0 in the out-of-band frequency so that oversampling is performed. After that, the inverse Fourier transform is performed, a guard interval is inserted into the signal subjected to the inverse Fourier transform, the analog signal is converted into a synchronized analog signal, and the frequency is converted. Generated and serially generated signals for each channel are combined to generate a broadband optical signal corresponding to the input signal. A transmission signal as a guru carrier signal, and a branch circuit in which the optical single-carrier signal branches the single carrier signal optical / electrical conversion, each corresponding to the channel of the single carrier signal, the channel corresponding to itself A plurality of processing units for demodulating the transmission signal, and a parallel-serial conversion unit for converting the transmission signal demodulated by the plurality of processing units into a serial signal and outputting the serial signal, and each of the processing units branches from the branch circuit A band pass filter that extracts a frequency region corresponding to the own channel from the single carrier signal and a signal that is extracted by the band pass filter are subjected to frequency conversion so that the center frequency of the frequency band used by the own channel is obtained. Over-sample the frequency conversion circuit and the signal frequency-converted by the frequency conversion circuit. An analog-to-digital conversion circuit that performs analog-to-digital conversion to a digital signal synchronized with a digital signal output from another processing unit, a Fourier-transform circuit that Fourier-transforms the digital signal converted by the analog-to-digital conversion circuit, and the Fourier transform A signal selection circuit that selects a predetermined digital signal to be demodulated in its own channel from digital signals converted by the circuit, and an equalization circuit that equalizes the digital signal selected by the signal selection circuit in the frequency domain And an inverse Fourier transform circuit for inverse Fourier transforming the digital signal equalized by the equalization circuit, and a demodulation circuit for demodulating the digital signal inversely Fourier transformed by the inverse Fourier transform circuit by a predetermined demodulation method. The parallel-serial conversion unit is configured so that each of the channels demodulated by the plurality of demodulation circuits is demodulated. A signal receiving apparatus characterized by converting a transmission signal for each channel into a serial signal.

  According to a second aspect of the present invention, the signal receiving device receives an optical single carrier signal, the signal receiving device outputs an optical signal, the received optical single carrier signal, and the local oscillation light source. A coupler that multiplexes the output light as an optical signal, and a balance receiver that optically / electrically converts the optical signal combined by the coupler and outputs it as an electric single carrier signal, and the branch circuit includes: The signal receiving apparatus according to claim 1, wherein the balance receiver branches an electric single carrier signal optical / electrically converted as the single carrier signal.

  According to a third aspect of the present invention, the signal receiving device detects a frequency deviation from the digital signal demodulated by the demodulation circuit, and adjusts an optical signal output from the local oscillation light source based on the detected frequency deviation. The signal receiving device according to claim 2, further comprising: a local oscillation light source adjustment unit that performs the operation.

  According to a fourth aspect of the present invention, each of the processing units includes a guard interval removal circuit that removes a guard interval from a digital signal that is analog-digital converted by the analog-digital conversion circuit, and the Fourier transform circuit includes the guard interval. 4. The signal receiving apparatus according to claim 1, wherein the removal circuit performs Fourier transform on the signal from which the guard interval is removed.

  According to a fifth aspect of the present invention, in the communication stage for determining the signal position of the guard interval to be removed by the guard interval removing circuit, the single carrier signal or the optical single carrier signal is any one of the channels determined in advance. Only one channel has guard interval position information indicating the signal position from which the guard interval is removed, and the other channel is configured not to interfere with the one channel. Or a guard interval position information detection unit for detecting guard interval position information included in the optical single carrier signal, and in the communication stage after the communication stage for determining the signal position of the guard interval, the guard intervals in the plurality of processing units Removal circuit 5. The signal reception according to claim 4, wherein the guard interval is removed from the digital signal analog-digital converted by the analog-to-digital conversion circuit based on the guard interval position information detected by the guard interval position information detection unit. Device.

  According to a sixth aspect of the present invention, in the communication step of determining a signal position of a Fourier transform window in which the Fourier transform circuit performs Fourier transform, the single carrier signal or the optical single carrier signal is one of predetermined channels. Only one channel has window position information indicating a signal position for detecting the window position, and the other channel is configured not to interfere with the one channel. A window position information detecting unit for detecting window position information included in a single carrier signal or an optical single carrier signal, and in a communication stage after a communication stage for determining a signal position of the Fourier transform window, in the plurality of processing sections A Fourier transform circuit is provided for the window position information. 2. The digital signal converted by the analog-to-digital conversion circuit or the signal from which the guard interval removal circuit has removed the guard interval is Fourier-transformed based on the window position information detected by the detection unit. Item 6. The signal receiving device according to any one of Item 5.

The invention according to claim 7 is a signal receiving apparatus that receives and demodulates an optical single carrier signal including a transmission signal, and the optical single carrier signal is obtained by performing parallel conversion on transmission data by the signal transmission apparatus, Each of the parallel-converted transmission data is modulated, Fourier-transformed, a zero frequency component is inserted into the frequency outside the band so as to be oversampled, and then subjected to inverse Fourier transform, to the inverse Fourier-transformed signal. Insert a guard interval, convert it to a synchronized analog signal, convert the frequency, extract a signal in the frequency band and generate a signal that removes the interference part, synthesize the signal of each channel generated serially, It generates a broadband optical signal corresponding to the input signal, a transmission signal as a broadband optical single-carrier signal, leaving the optical signal A local oscillation light source, an optical 90 ° hybrid coupler that combines the received optical single carrier signal and the light output from the local oscillation light source to output optical signals of I phase and Q phase, and the optical 90 ° I-phase balanced receiver that is a balanced receiver that converts an I-phase optical signal output by the hybrid coupler into an electrical signal and outputs it as an I-phase single carrier signal, and a Q-phase output from the optical 90 ° hybrid coupler A Q-phase balanced receiver that is a balanced receiver that converts an optical signal into an electrical signal and outputs it as a Q-phase single carrier signal, an I-phase single carrier signal that is output from the I-phase balanced receiver, and the Q-phase balanced receiver And a demodulator that demodulates the Q-phase single carrier signal output from the transmitter and outputs a transmission signal. A plurality of processing units for demodulating a transmission signal of a channel corresponding to the channel of the single carrier signal, a parallel serial conversion unit for converting the transmission signals demodulated by the plurality of processing units into a serial signal and outputting the serial signal; And each of the processing units extracts a frequency region corresponding to its own channel from an I-phase single carrier signal output by the I-phase balanced receiver, and the I-phase bandpass filter, A Q-phase band-pass filter that is a band-pass filter that extracts a frequency region corresponding to its own channel from a Q-phase single carrier signal output from the Q-phase balanced receiver, a signal extracted by the I-phase band-pass filter, and the Q The signal extracted by the phase bandpass filter and the center frequency of the frequency band used by the own channel A frequency conversion circuit that performs frequency conversion so as to be a number, and outputs the signal as an I-phase and Q-phase frequency converted signal, and oversamples the I-phase signal frequency-converted by the frequency conversion circuit and other processing units The I-phase analog-to-digital conversion circuit, which is an analog-to-digital conversion circuit that performs analog-to-digital conversion to a digital signal that is synchronized with the digital signal output from the digital signal, and the Q-phase signal frequency-converted by the frequency conversion circuit are oversampled and subjected to other processing A Q-phase analog-to-digital conversion circuit that is an analog-to-digital conversion circuit that performs analog-to-digital conversion to a digital signal that is synchronized with the digital signal output by the unit, and a Fourier transform circuit that performs a Fourier transform on the digital signal converted by the I-phase analog-to-digital conversion circuit An I-phase Fourier transform circuit and the Q A Q-phase Fourier transform circuit, which is a Fourier transform circuit that Fourier-transforms a digital signal converted by the analog-digital conversion circuit, and a digital signal converted by the I-phase Fourier transform circuit are predetermined as demodulation targets in the own channel. A signal for selecting a digital signal predetermined as a demodulation target in its own channel from among an I-phase signal selection circuit which is a signal selection circuit for selecting a digital signal and a digital signal converted by the Q-phase Fourier transform circuit A Q-phase signal selection circuit as a selection circuit, an I-phase equalization circuit for equalizing the digital signal selected by the I-phase signal selection circuit in the frequency domain, and a digital signal selected by the Q-phase signal selection circuit in the frequency domain Q-phase equalization circuit to equalize, digital signal equalized by the I-phase equalization circuit and digital equalization by the Q-phase equalization circuit The inverse Fourier transform circuit for inverse Fourier transform and No., have, a demodulation circuit for demodulating by said inverse Fourier transform circuit is an inverse Fourier transform to the digital signal a predetermined demodulation method, the parallel-serial conversion unit, the plurality The signal receiving apparatus is characterized in that a transmission signal for each channel demodulated by the demodulation circuit is converted into a serial signal.

  According to an eighth aspect of the present invention, the signal receiving device detects a frequency deviation from the digital signal demodulated by the demodulation circuit, and adjusts an optical signal output from the local oscillation light source based on the detected frequency deviation. The signal receiving device according to claim 7, further comprising: a local oscillation light source adjustment unit that performs the operation.

  The invention according to claim 9 is an I-phase guard interval removal circuit, which is a guard interval removal circuit that removes a guard interval from a digital signal that the processing unit analog-digital converts by the I-phase analog-digital conversion circuit, A Q-phase guard interval removing circuit that is a guard interval removing circuit that removes a guard interval from a digital signal obtained by analog-digital conversion by the Q-phase analog-digital conversion circuit, and the I-phase Fourier transform circuit includes the I-phase guard interval. 8. The signal from which the removal circuit has removed the guard interval is Fourier-transformed, and the Q-phase Fourier transform circuit is to Fourier-transform the signal from which the Q-phase guard interval removal circuit has been removed. Claim 8 Is an issue receiving device.

  According to a tenth aspect of the present invention, in the communication stage for determining the signal position of the guard interval to be removed by the guard interval removal circuit, the single carrier signal or the optical single carrier signal is any one of the channels determined in advance. Only one channel has guard interval position information indicating the signal position from which the guard interval is removed, and the other channel is configured not to interfere with the one channel. Or a guard interval position information detection unit that detects guard interval position information included in the optical single carrier signal, and in the communication stage after the communication stage for determining the signal position of the guard interval, the I phase in the plurality of processing units Guard interval removal The path removes a guard interval from the digital signal analog-digital converted by the I-phase analog-digital conversion circuit based on the guard interval position information detected by the guard interval position information detection unit, and the Q phase in the plurality of processing units The guard interval removing circuit removes the guard interval from the digital signal analog-digital converted by the Q-phase analog-digital conversion circuit based on the guard interval position information detected by the guard interval position information detecting unit. A signal receiving device according to claim 9.

  According to the eleventh aspect of the present invention, in the communication step of determining a signal position of a Fourier transform window in which the Fourier transform circuit performs Fourier transform, the single carrier signal or the optical single carrier signal is any one of the channels determined in advance. Only one channel has window position information indicating a signal position for detecting the window position, and the other channel is configured not to interfere with the one channel. A window position information detecting unit for detecting window position information included in a single carrier signal or an optical single carrier signal, and in a communication stage after a communication stage for determining a signal position of the Fourier transform window, in the plurality of processing sections I-phase Fourier transform circuit Based on the window position information detected by the position information detection unit, the digital signal converted by the I-phase analog-to-digital conversion circuit or the signal from which the I-phase guard interval removal circuit has removed the guard interval is Fourier transformed, and the plurality of processes The Q-phase Fourier transform circuit in the unit removes the guard interval based on the digital signal converted by the Q-phase analog-digital conversion circuit or the Q-phase guard interval removal circuit based on the window position information detected by the window position information detection unit The signal reception device according to claim 7, wherein the received signal is Fourier-transformed.

  A twelfth aspect of the present invention is a signal receiving system having a plurality of signal receiving apparatuses according to any one of the second to eleventh aspects, wherein the plurality of signal receiving apparatuses demodulate channels of different frequency bands. The signal receiving system demultiplexes the received optical single carrier signal into a channel of a frequency band demodulated by the plurality of signal receiving devices, and the demultiplexed optical single carrier signal has a frequency band. An optical demultiplexing unit that outputs the signal to the corresponding signal receiving device; and each of the plurality of signal receiving devices demodulates an optical single carrier signal of a channel input from the optical demultiplexing unit. A signal receiving system.

  According to a thirteenth aspect of the present invention, the optical demultiplexing unit receives the received optical single so that a frequency band of the demultiplexed channel is wider than at least a frequency band demodulated by the corresponding signal receiving apparatus. 13. The signal receiving system according to claim 12, wherein the carrier signal is demultiplexed into a channel of a frequency band demodulated by the plurality of signal receiving apparatuses.

The invention according to claim 14 is a signal receiving method used in a signal receiving apparatus for receiving and demodulating an optical single carrier signal including a transmission signal, wherein the optical single carrier signal is transmitted from a signal transmitting apparatus by transmission data. Is converted into parallel, and each of the parallel-converted transmission data is modulated, Fourier-transformed, and a frequency component of 0 is inserted in the frequency outside the band so that oversampling is performed, and then inverse Fourier transform is performed. Each channel generated serially is generated by inserting a guard interval into the Fourier-transformed signal, converting it to a synchronized analog signal, converting the frequency, extracting the signal in the frequency band, and removing the interference part. Are combined to generate a broadband optical signal corresponding to the input signal, which is converted into a broadband optical single carrier signal. A transmitted signal, demodulated and branch instructions to branch a single carrier signal, wherein the optical single-carrier signal is an optical / electrical conversion, each corresponding to the channel of the single carrier signal, the transmission signal of the channel corresponding to itself It has to a plurality of processing procedures, and a parallel-to-serial conversion procedure for outputting the transmission signal demodulated by the plurality of processing steps to convert the serial signal, a single carrier in which the procedure is respectively branched at the branch instructions A bandpass filter procedure for extracting a frequency region corresponding to the own channel from the signal, and a frequency at which the signal extracted by the bandpass filter procedure is subjected to frequency conversion so as to be a center frequency of a frequency band used by the own channel. Oversampling the conversion procedure and the frequency converted signal in the frequency conversion procedure An analog-to-digital conversion procedure for analog-to-digital conversion into a digital signal synchronized with a digital signal output by another processing procedure, a Fourier-transform procedure for Fourier-transforming the digital signal converted by the analog-to-digital conversion procedure, and the Fourier-transform procedure A signal selection procedure for selecting a predetermined digital signal to be demodulated in the own channel from the digital signals converted in step 1, and an equalization procedure for equalizing the digital signal selected in the signal selection procedure in the frequency domain, An inverse Fourier transform procedure for inverse Fourier transforming the digital signal equalized by the equalization procedure, and a demodulation procedure for demodulating the digital signal inverse Fourier transformed by the inverse Fourier transform procedure by a predetermined demodulation method, Each of the parallel-serial conversion procedures is demodulated by the plurality of demodulation procedures. A signal receiving method characterized by converting a transmission signal for each channel into a serial signal.

  According to the present invention, real-time and high-quality broadband transmission reception can be realized. In addition, since the single carrier is divided into multiple channels and digital processing such as guard interval removal and Fourier transform is performed in parallel for each channel, the clock is slower than when the single carrier is not divided into multiple channels. It is also possible to operate digital processing.

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

<First Embodiment>
FIG. 1 is a block diagram showing a configuration of a signal receiving apparatus 1 according to the first embodiment of the present invention. The signal receiving apparatus 1 receives a broadband optical single carrier signal divided into a plurality of channels including transmission data, demodulates the transmission data from the received signal, and outputs it as binary data.

  Here, a signal transmission apparatus as an example for transmitting the broadband optical single carrier signal will be described. This signal transmission device performs parallel conversion on transmission data, modulates each of the parallel-converted transmission data, performs Fourier transformation, and inserts a frequency component of 0 to a frequency outside the band so that oversampling is performed. Apply inverse Fourier transform. Further, a guard interval is inserted into the signal subjected to inverse Fourier transform. Further, after conversion to a synchronized analog signal and frequency conversion, a signal in a frequency band is extracted to generate a signal from which an interference portion is removed. Then, the serially generated signals of the respective channels are combined to generate a broadband optical signal corresponding to the input signal, and transmitted as a broadband optical single carrier signal. Here, although a frequency component of 0 is inserted in the frequency outside the band, interference with an adjacent channel can also be reduced by using a band limiting filter such as a root Nyquist filter.

Returning to the description of FIG. 1, the signal receiving apparatus 1 includes a local oscillation light source 2, a coupler 3, a balance receiver 4, and a demodulator 5. The broadband optical single carrier signal carrying the signal on the optical carrier having the frequency fc is combined with the optical signal having the frequency f _L0 from the local oscillation light source 2 by the coupler 3. Next, it is optical / electrically converted by the balance receiver 4 and output to the demodulator 5 as a broadband electric single carrier signal.

The balance receiver 4 optically / electrically converts the optical signal combined by the coupler 3 by, for example, heterodyne detection. In this balanced receiver 4, not only optical / electrical conversion but also the frequency fc of the optical carrier and the frequency f _{L0 of the} local oscillation light source 2 with respect to the broadband electric single carrier signal output from the balanced receiver 4. Is converted into an IF (Intermediate Frequency) band.

  The broadband electric single carrier signal output from the balance receiver 4 is input to the demodulator 5 and demodulated into binary data by the demodulator 5.

<Configuration of Demodulator 5>
Next, the configuration of the demodulator 5 shown in FIG. 1 will be described with reference to FIG. The branch circuit 50 branches the broadband electric single carrier signal output from the balance receiver 4 to the BPF 51-i (i = 1 to k) and outputs it. The BPF 51-i (i = 1 to k) is a predetermined frequency band used by each channel corresponding to the BPF 51-i (i = 1 to k) from the broadband electric single carrier signal input by the branch circuit 50. Are extracted and output. Hereinafter, the channels corresponding to the BPF 51-i (i = 1 to k) are respectively referred to as channels i. In addition, the center frequency of the frequency band extracted by the BPF 51-i (i = 1 to k) is referred to as a center frequency fi.

  The frequency conversion circuit 52-i (i = 1 to k) uses the oscillation signal from the local oscillator 61 to extract the frequency of the broadband electric single carrier signal extracted by the BPF 51-i, that is, the frequency of the analog signal. Convert. In this case, the frequency conversion circuit 52-i (i = 1 to k) determines the center frequency (hereinafter referred to as the center frequency in the frequency band) in the broadband electric single carrier signal extracted and output by the BPF 51-i. The frequency conversion is performed so that “the center frequency of the frequency band” is described as “the center frequency of the frequency band used by the channel”.

  The A / D conversion circuit 53-i (i = 1 to k) converts the analog signal frequency-converted by the frequency conversion circuit 52-i into a digital signal synchronized with the clock signal from the common clock 62. Accordingly, the digital signals output from the A / D conversion circuit 53-i (i = 1 to k) are synchronized with each other. The A / D conversion circuit 53-i performs oversampling and converts it into a digital signal synchronized with the clock signal from the common clock 62. For example, the A / D conversion circuit 53-i oversamples transmission information of 64 samples as transmission information of 256 samples, which is four times as much. Here, although described as four times, for example, two times or one time oversampling may be used.

  The GI (guard interval) removal circuit 54-i (i = 1 to k) removes the guard interval from the digital signal converted by the A / D conversion circuit 53-i.

  A discrete Fourier transform (DFT) circuit 55-i (i = 1 to k) performs a Fourier transform on the digital signal from which the GI removal circuit 54-i has removed the guard interval. The DFT circuit 55-i may perform Fourier transform on the digital signal from which the GI removal circuit 54-i has removed the guard interval by fast Fourier transform (FFT). Note that the DFT circuit 55-i performs Fourier transform with the number of points equal to or greater than the number of points in the channel i in order to convert the digital signal converted by oversampling by the A / D conversion circuit 53-i.

  For example, when the A / D conversion circuit 53-i oversamples transmission information of 64 samples as transmission information of 256 samples multiplied by 4, this DFT circuit 55-i (i = 1 to k) also has 256 samples. Fourier transform is performed with 256 points corresponding to.

  The signal selection circuit 56-i (i = 1 to k) selects (extracts) a digital signal predetermined as a demodulation target in the channel i from the digital signal Fourier-transformed by the DFT circuit 55-i and outputs it. . This signal selection circuit 56-i (i = 1 to k) is, for example, 256 when the DFT circuit 55-i (i = 1 to k) performs Fourier transform with 256 points corresponding to 256 samples. Among the points, a 64-point digital signal which is a central region is selected.

  The equalization circuit 57-i (i = 1 to k) equalizes and outputs the digital signal to be demodulated in the channel i selected by the signal selection circuit 56-i (i = 1 to k) in the frequency domain. . For the equalization in the frequency domain by the equalization circuit 57-i (i = 1 to k), for example, FDE (Frequency Domain Equalization) technology is used.

  An inverse discrete Fourier transform (IDFT) circuit 58-i (i = 1 to k) performs an inverse Fourier transform on the digital signal equalized by the equalization circuit 57-i (i = 1 to k). The IDFT circuit 58-i performs inverse Fourier transform on the digital signal equalized by the equalization circuit 57-i (i = 1 to k) by inverse fast Fourier transform (IFFT). You may go. The IDFT circuit 58-i performs inverse Fourier transform with the same number of points as the digital signal equalized by the equalization circuit 57-i (i = 1 to k).

  The demodulation circuit 59-i (i = 1 to k) demodulates the digital signal obtained by the inverse discrete Fourier transform (IDFT) circuit 58-i (i = 1 to k) into binary data by a predetermined demodulation method. To do. For example, the demodulating circuit 59-i (i = 1 to k) uses 16QAM (Quadrature Amplitude Modulation), 64QAM, QPSK (Quadrature Phase Shift Keying), etc. as predetermined demodulation methods. A corresponding demodulation method is used. This predetermined demodulation method is a demodulation method corresponding to a modulation method used in a signal transmission device that transmits a broadband optical single carrier signal.

  The P / S (parallel / serial) conversion circuit 60 inputs the digital signal demodulated by the demodulation circuit 59-i (i = 1 to k) in parallel for each channel i as binary data. Binary data is converted to serial data and output.

<Operation of Signal Receiver 1>
Next, the operation of the signal receiving apparatus 1 described with reference to FIGS. 1 and 2 will be described with reference to FIGS. First, the coupler 3 of the signal receiving apparatus 1 that has received a broadband optical single carrier signal in which a single carrier signal is carried on an optical carrier having a frequency fc, has a frequency f _L0 from the received broadband optical single carrier signal and the local oscillation light source 2. Combines with optical signal.

  FIG. 3 shows a waveform as an example of a broadband optical single carrier signal received by the coupler 3 of the signal receiving apparatus 1. As shown in FIG. 3, the broadband optical single carrier signal has a waveform centered on the frequency fc of the optical carrier, and the signal is distorted as it propagates through the transmission line. The spectrum is In the figure, the frequency band extracted later by BPF 51-i (i = 1 to k) and the center frequency fi (i = 1 to k) are shown.

Next, the balance receiver 4 optically / electrically converts the optical signal combined by the coupler 3 by, for example, heterodyne detection, and the difference between the frequency fc of the optical carrier and the frequency f _L0 of the local oscillation light source 2 is calculated. The frequency is converted to an IF (Intermediate Frequency) band, and is output to the demodulator 5 as a broadband electric single carrier signal.
FIG. 4 shows a waveform as an example of a wideband electric single carrier signal frequency-converted to the IF band output from the balance receiver 4 to the demodulator 5.

  Next, the branch circuit 50 of the demodulator 5 to which the wideband electric single carrier signal output from the balance receiver 4 is input, converts the wideband electric single carrier signal output from the balance receiver 4 into the BPF 51-i (i = 1 to k) and output.

Next, the BPF 51-i (i = 1 to k) is determined in advance from the broadband electric single carrier signal input by the branch circuit 50 and used by the channel i corresponding to the BPF 51-i (i = 1 to k). The frequency band signal is extracted and output to the frequency conversion circuit 52-i (i = 1 to k).
FIG. 5 shows a frequency band as an example that BPF 51-i (i = 1 to k) extracts from a broadband electric single carrier signal.

Next, the frequency conversion circuit 52-i (i = 1 to k) uses the oscillation signal from the local oscillator 61 to extract the frequency of the broadband electric single carrier signal output by the BPF 51-i, that is, an analog signal. Is converted to a center frequency of the frequency band used by the channel i, and output to the A / D conversion circuit 53-i (i = 1 to k).
FIG. 6 shows frequency conversion as an example by the frequency conversion circuit 52-i (i = 1 to k).

Next, the A / D conversion circuit 53-i (i = 1 to k) oversamples the analog signal frequency-converted by the frequency conversion circuit 52-i into a digital signal synchronized with the clock signal from the common clock 62. Are converted and output to the GI removal circuit 54-i (i = 1 to k).
Next, the GI removal circuit 54-i (i = 1 to k) removes the guard interval from the digital signal converted by the A / D conversion circuit 53-i, and the Fourier transform circuit 55-i (i = 1). To k).

  Next, the Fourier transform circuit 55-i (i = 1 to k) performs Fourier transform on the digital signal from which the GI removal circuit 54-i has removed the guard interval, and the digital signal obtained by the Fourier transform is converted to the signal selection circuit 56. -I (i = 1 to k) Since the Fourier transform circuit 55-i converts the digital signal converted by oversampling by the A / D conversion circuit 53-i, the Fourier transform is performed with the number of points equal to or greater than the number of points in the channel i. Do.

Next, the signal selection circuit 56-i (i = 1 to k) selects a signal predetermined as a demodulation target in the channel i from the digital signal Fourier-transformed by the Fourier transform circuit 55-i, etc. Output to the circuit 57-i (i = 1 to k).
FIG. 7 shows an exemplary signal selected by the signal selection circuit 56-i (i = 1 to k).

Next, the equalization circuit 57-i (i = 1 to k) equalizes the digital signal to be demodulated in the channel i selected by the signal selection circuit 56-i (i = 1 to k), and the IDFT circuit 58-i (i = 1 to k).
Next, the inverse Fourier transform circuit 59-i (i = 1 to k) performs an inverse Fourier transform on the digital signal equalized by the equalization circuit 57-i (i = 1 to k), and this inverse Fourier transform is performed. The converted digital signal is output to the demodulation circuit 59-i (i = 1 to k).

  Next, the demodulation circuit 59-i (i = 1 to k) demodulates the digital signal obtained by the inverse Fourier transform by the inverse Fourier transform circuit 59-i (i = 1 to k) into binary data by a predetermined demodulation method. To the P / S conversion circuit 60.

  Next, the P / S conversion circuit 60 receives binary data, which is a digital signal demodulated by the demodulation circuit 59-i (i = 1 to k), in parallel for each channel i. Data is converted into serial data and output.

  As described above, the demodulator 5 according to the present embodiment branches the broadband optical single carrier signal into a plurality of channels by a branch circuit and separates the extracted frequency band into a plurality of channels, and each channel performs a Fourier transform. The frequency is converted to a frequency that enables Next, oversampling is performed by an A / D converter and conversion into a digital signal, and Fourier transform is performed with the number of points equal to or greater than the number of subcarriers of each channel. Next, only the signals to be demodulated in each channel are extracted from the output of the Fourier transform, equalization processing is performed, the inverse Fourier transform is performed on the equalized processing signal, and the result of the demodulation processing is parallelized. / Transmission data included in the broadband optical single carrier signal is received by serial conversion.

  Further, the demodulator 5 according to this embodiment performs Fourier transform in parallel for each band corresponding to the channel so that oversampling is performed before the Fourier transform. By extracting only the signals that are present, a steep digital filter is realized, and it is possible to eliminate interference from peripheral channels together with the BPF for analog signals. In addition, a steep BPF that is difficult to achieve with only an analog filter is realized, and the interference from the outside of the divided band can be removed.

  Also, circuits that perform digital data processing, such as DFT circuits, GI elimination circuits, demodulation circuits, and IDFT circuits, perform data processing in parallel on data divided into channels, so that data is processed without being divided into channels. In contrast to this, it is possible to operate the data processing with a slow clock, so that the signal processing for the ultra-wideband input signal can be realized in real time.

<Signal position detection of guard interval>
Next, a method for determining the signal position of the guard interval to be removed by the GI removal circuit 54-i (i = 1 to k) will be described.

  First, in the communication stage in which the signal position of the guard interval to be removed by the GI removal circuit 54-i (i = 1 to k) is determined, the signal transmission apparatus is configured such that only one of the predetermined channels is the guard interval. A wideband optical single carrier signal is transmitted so that the other channel does not interfere with one channel.

  For example, the signal transmission apparatus transmits information in which the guard interval is inserted only in channel 1 of the channels, and transmits only signal 0 in the other channels 2 to k.

  In addition, the demodulator 5 includes a guard interval position information detection unit that detects guard interval position information included in the single carrier signal. This guard interval position information detection unit may correspond to only one of predetermined channels.

  In the subsequent communication stage, that is, in the stage where each channel is used for normal communication and has a guard interval, the GI removal circuits 54-i (i = 1 to k) in the plurality of processing units are guard interval position information detection units. Based on the guard interval position information detected by, the frequency conversion circuit 52-i (i = 1 to k) removes the guard interval from the frequency converted signal.

  As described above, the guard interval position information detection unit can detect the guard interval position information because no interference occurs between the subcarriers in the communication stage for determining the signal position of the guard interval. Further, according to the guard interval signal position detected by the guard interval position information detection unit, in the subsequent communication stage, that is, in the stage where each channel has a guard interval, the GI removal circuit 54-i (i = 1 to k) It is possible to remove the guard interval.

<Fourier transform window signal position detection>
Next, a method for determining the signal position of the Fourier transform window in which the DFT transform circuit 55 performs Fourier transform will be described.

  In the communication stage for determining the signal position of the Fourier transform window where the DFT transform circuit 55 performs the Fourier transform, the signal transmission device indicates the signal position for detecting any one of the predetermined channels among the channels. A broadband optical single carrier signal is transmitted in such a way that window position information is included and other channels do not interfere with one channel.

  For example, the signal transmission apparatus transmits window position information only on channel 1, and transmits only signal 0 on the other channels 2 to k.

  In addition, the demodulator 5 includes a window position information detection unit that detects window position information included in the single carrier signal. This window position information detection unit may correspond to only one of the predetermined channels.

  In the subsequent communication stage, that is, in the stage where the normal communication is also used for each channel, the DFT conversion circuit 55-i (i = 1 to k) is based on the window position information detected by the window position information detection unit. The digital signal converted by the A / D conversion circuit 53-i (i = 1 to k) is Fourier-transformed.

  As described above, the window position information detection unit can detect the window position information because no interference occurs between channels in the communication stage for determining the signal position of the Fourier transform window. Further, the DFT conversion circuit 55-i (i = 1 to k) in the subsequent communication stage, that is, in the stage where the normal communication is also used for each channel, based on the window position information detected by the window position information detection unit. However, the digital signal converted by the A / D conversion circuit 53-i (i = 1 to k) can be Fourier-transformed.

<Adjustment of local oscillator 61>
Next, adjustment of the optical signal output from the local oscillator 61 will be described. The demodulator 5 detects a frequency deviation from the digital signal demodulated by the demodulation circuit 58-i (i = 1 to k), and adjusts the optical signal output from the local oscillator 61 based on the detected frequency deviation. It has an adjustment part. By applying feedback to the local oscillator 61 by the local oscillator adjusting unit, the signal quality of the signal detected by the heterodyne detection or the homodyne detection by the balance receiver 4 is improved.

Here, a plurality of blocks (frequency band blocks) in which a single carrier signal is divided by a band pass filter of BPF 51-i (i = 1 to k) will be described with reference to FIG.
The signal receiving apparatus 1 demodulates the single carrier signal by dividing it into a plurality of blocks i (i = 1 to k) by a band pass filter of BPF 51-i (i = 1 to k). At this time, the pass band of the BPF 51-i (i = 1 to k) is set wider than the band of the block to be demodulated. Since the data symbols input to the demodulator 5 have a wide passband of the BPF 51-i (i = 1 to k) and contain unnecessary frequency components, only the symbols of the necessary frequency components are selected. The data is taken out by the circuit 56-i, subjected to IDFT conversion by the IDFT circuit 58-i, and then demodulated by the demodulation circuit 59-i (i = 1 to k).

  Here, Δfi (i = 1 to k) indicates a frequency band to be demodulated in the broadband optical single carrier signal. Further, by setting the pass band wider than the desired frequency band of 2δfi (i = 1 to k), the channel of Δfni (i = 1 to k) is not distorted by the filter.

The frequency conversion circuit 51-i (i = 1 to k) performs frequency conversion to the baseband, and the A / D conversion circuit 53-i (i = 1 to k) performs Δfi + 2δfi (i = 1 to k). By oversampling at the above sampling frequency, the data symbol of the channel to be demodulated is not affected by filtering by the BPF 51-i (i = 1 to k) and demodulated by the demodulation circuit 58-i (i = 1 to k). Is done.
As described above, it is possible to arrange the broadband optical single carrier signal without a guard band without inserting a guard band, thereby improving the frequency utilization efficiency.

<Second Embodiment>
Next, a signal receiving apparatus 1A according to the second embodiment will be described with reference to FIG. In the subsequent drawings, the same components as those of the signal receiving device 1 according to the first embodiment described with reference to FIG. 1 or FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted.

  In addition, about the structure which has the same function, while attaching | subjecting the same code | symbol, code | symbols, such as code | symbol I, code | symbol Q, code | symbol A, etc., are attached, and only the difference is demonstrated. The symbol I indicates the I phase, the symbol Q indicates the Q phase, and the symbol A indicates that the configuration functions are different.

  9 includes an optical 90 ° hybrid coupler 6, a local oscillation light source 2, balanced receivers 7 and 8, and a demodulator 5A. The optical 90 ° hybrid coupler 6 combines the received optical single carrier signal and the light output from the local oscillation light source 2 and outputs an optical signal of I phase and Q phase. Details of the optical 90 ° hybrid coupler 6 will be described later with reference to FIGS.

  The balanced receiver 7 converts the I-phase optical signal output from the optical 90 ° hybrid coupler 6 into an I-phase electrical signal, and outputs it to the demodulator 5A. The balanced receiver 8 converts the Q-phase optical signal output from the optical 90 ° hybrid coupler 6 into a Q-phase electric signal and outputs the Q-phase optical signal to the demodulator 5A. The balanced receivers 7 and 8 are each composed of two photodiodes that are matched, and generate differential signals of photocurrents detected by the respective photodiodes. The balanced receiver here is a balanced photo receiver or an optical balanced receiver.

  The demodulator 5A corresponds to the demodulator 5 according to the first embodiment, but is different from the demodulator 5 according to the first embodiment in that signal processing is performed in parallel on the I phase and the Q phase.

  In the signal receiving apparatus 1 according to the first embodiment, the balanced receiver 4 performs optical / electrical conversion by heterodyne detection, and the branching circuit 50 is used to branch the broadband optical single carrier signal. In the signal receiving apparatus 1 according to the second embodiment shown, heterodyne / homodyne detection can be performed using the optical 90 ° hybrid coupler 6 and the balanced receivers 7 and 8 to separate the I-phase component and the Q-phase component.

  In the demodulator 5A of the signal receiving apparatus 1A according to the second embodiment, the frequency conversion circuit 52-i-IQ extracts and outputs the I-phase broadband output by the BPF 51-i-I (i = 1 to k). About the frequency-converted signal with respect to the frequency of the electric single carrier signal and the frequency of the Q phase broadband electric single carrier signal extracted and output by BPF51-i-Q (i = 1 to k), The I-phase component is output to the A / D conversion circuit 53-i-I (i = 1 to k), and the Q-phase component is output to the A / D conversion circuit 53-i-Q (i = 1 to k). This is different from the demodulator 5 of the signal receiving apparatus 1 according to the first embodiment.

The outputs of the A / D conversion circuit 53-i-I and the A / D conversion circuit 53-i-Q are input to the digital signal processing unit 70-i (i = 1 to k). The configuration of the signal processing unit 70-i (i = 1 to k) is the first embodiment described with reference to FIG. 2 except that the configuration includes an I phase and a Q phase as shown in FIG. This is the same as the demodulator 5 of the signal receiver 1 according to the above.
However, the demodulation circuit 58A-i (i = 1 to k) is connected to the I-phase signal from the I-phase equalization circuit 58-i-I (i = 1 to k) and the Q-phase equalization circuit 58-i. The demodulator 5A of the signal receiving apparatus 1A according to the second embodiment and the signal receiving apparatus 1 according to the first embodiment demodulate based on the Q-phase signal from -Q (i = 1 to k). It differs from the demodulator 5.

<General example of photoelectric converter using 90 ^o hybrid>
Next, the photoelectric conversion unit using the optical ^90o hybrid coupler 6 will be described with reference to FIG. The optical 90 ^o hybrid coupler 6 includes an optical 3 dB coupler 601 and polarization beam splitters 602 and 603.

The optical 90 ^o hybrid coupler 6 receives the signal light via the polarization controller 622, and combines the input signal light and the light output from the local oscillation light source 600 to generate an optical signal of I phase and Q phase. Is output via the polarization beam splitters 602 and 603.

  The balanced receiver 603 converts the I-phase optical signal output from the optical 90 ° hybrid coupler 6 into an I-phase electrical signal. The balanced receiver 613 converts the Q-phase optical signal output from the optical 90 ° hybrid coupler 6 into a Q-phase electrical signal. The balanced receiver 603 has two photodiodes 604 and 605 that are matched. The balanced receiver 613 includes two photodiodes 614 and 615 that are matched.

  The output of the balanced receiver 603 is combined with the oscillation signal from the local oscillator 620 by the multiplexer 606 and input to the low pass filter LPF 607. The output of the balanced receiver 613 is combined with the oscillation signal from the oscillation signal from the local oscillator 620 by the multiplexer 616 and input to the low pass filter LPF 617. Note that the oscillation signal from the local oscillator 620 input to the multiplexer 616 is an oscillation signal whose phase is shifted by π / 2 by the phase shifter 621. Therefore, the oscillation signals from the local oscillator 620 input to the multiplexer 606 and the multiplexer 616 are shifted from each other by π / 2.

Here, E _s (t) is the transmitted signal light, and E _L (t) is the electric field of the local oscillation light source 600. For the sake of simplicity, the explanation will be made assuming that the signal light is linearly polarized and the local oscillation light source is circularly deflected.

The signal light E _s (t) and the electric field E _L (t) can be expressed as the following (Equation 1). In (Equation 1), X and Y are unit vectors in the orthogonal polarization direction. Φ (t) is a phase noise term.

  Here, the complex symbol S (t) is expressed by the following (Equation 2) using I (t) and Q (t) as real signals.

Next, the local oscillation light source 600 and the signal light are combined by the optical 3 dB coupler 601, and the output light E _A (t) and the output light E _B (t) output from the optical 90 ^o hybrid coupler 6 are From (Equation 3) to (Equation 6).

The output light E _A (t) and the output light E _B (t) are divided into orthogonal X and Y components by the polarization beam splitters 602 and 603. The output electric fields of the four ports of the 90 ^° hybrid coupler 6 are expressed by the following (Expression 7) to (Expression 10).

Here, when balanced receivers 603 and 613 are used as the optical / electrical converters, the reception current can be expressed as the following (Expression 11) and (Expression 12). Here, ω _IF = ω ₀ −ω _L represents an intermediate angular frequency.

<In the case of (ω _IF = 0)>
When this ω _IF is 0 (ω _IF = 0), homodyne reception is performed, and I (t) and Q (t) are obtained directly from the outputs i1 and i2 from the balanced receivers 603 and 613. In this case, the phase of the carrier wave of the signal light and the local oscillation light must be aligned, and feedback phase control and a phase shift compensation circuit are required at the receiving unit.

<When (ω _IF ≠ 0)>
On the other hand, when this ω _IF is not 0 (ω _IF ≠ 0), the baseband signal is further converted into the baseband signal by the following (Equation 13) and (Equation 14) using the local oscillation source (angular frequency: ω _IFLo ). Convert frequency.

When the high frequency component ω _IF + ω _IFLo is removed by the low-pass filters 607 and 617 and the phase noise φ (t) and the frequency offset of the local oscillator are assumed to be 0 for the sake of simplicity, the following (Equation 15) Thus, the I-phase component of the transmitted signal can be extracted.

  Similarly, the Q phase can also be demodulated as the following (Expression 16).

<When a ^90o hybrid photoelectric conversion unit is applied to a broadband optical single carrier signal>
Next, a case where the photoelectric conversion unit using the 90 ^° hybrid coupler 6 is applied to a broadband optical single carrier signal, that is, a case where it is applied to the signal receiving apparatus 1A will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the structure same as FIG. 11, and the description is abbreviate | omitted. In FIG. 12, only one channel is shown and described for explanation.

In the case of a broadband optical single carrier signal, instead of (Equation 2), the following (Equation 17) is used, and the following reception configuration / calculation procedure is performed in the same manner as described in the general example above. As shown in (Equation 18) and (Equation 19), I-phase and Q-phase components are obtained as i _B1 and i _B2 .

By using i _B1 and i _B2 as inputs of a demodulator 5A (here, demodulator 5B), it is possible to demodulate transmission data from a broadband optical single carrier signal, as in the first embodiment. Become.

  Note that, in the signal receiving device 1A of FIG. 9 and the signal receiving device 1A of FIG. 12, the balanced receiver 7 corresponds to the balanced receiver 603, and the balanced receiver 8 corresponds to the balanced receiver 613. BPF 51 -i-I corresponds to the low-pass filter 607 and the multiplexer 606, and BPF 51 -i-Q corresponds to the low-pass filter 617 and the multiplexer 616.

  9 and FIG. 12, BPF51-i-I and BPF51-i-Q (i = 1 to k) correspond to the low-pass filters 607 and 617, but the demodulator 5A has BPF51-i-I and Q. (I = 1 to k) inside, and the demodulator 5B is different in that low pass filters 607 and 617 are outside.

  Similar to the first embodiment shown in FIG. 8, in the second embodiment, the single carrier signals are bandpassed with BPF51-i-I and BPF51-i-Q (i = 1 to k). The signal is demodulated by dividing it into a plurality of blocks.

In addition, by heterodyne / homodyne detection using the optical 90 ° hybrid coupler 6 and the balanced receivers 7 and 8, the broadband optical single carrier signal is frequency-converted to an intermediate frequency or baseband, respectively. The frequency-converted signal is filtered by a BPF having k branches and a passband of Δfi + 2δfi (i = 1 to k).
In the subsequent signal processing, similarly to the first embodiment, in the second embodiment, the signal is processed in a plurality of blocks.
Thus, similarly to the first embodiment, in the second embodiment, the broadband optical single carrier signal can be arranged without a gap without inserting a guard band, and the frequency utilization efficiency is improved. Can be planned. Note that a single-ended receiver may be used instead of the balanced receiver.

<Third Embodiment>
Next, a signal receiving apparatus according to the third embodiment will be described with reference to FIG. Here, the signal receiving apparatus according to the third embodiment will be described as a signal receiving system.

  This signal receiving system includes a plurality of signal receiving apparatuses 101 which are the signal receiving apparatus 1 or the signal receiving apparatus 1A described in the first embodiment or the second embodiment. In FIG. 13, the signal receiving system includes n signal receiving apparatuses 101. This signal receiving apparatus 101 is described as signal receiving apparatus 101-i (i = 1 to n). The plurality of signal receiving apparatuses 101-i (i = 1 to n) are set in advance so as to demodulate wideband single carrier signals of different frequency bands.

  In addition, this signal receiving system demultiplexes the received optical single carrier signal into signals in a frequency band demodulated by a plurality of signal receiving apparatuses 101-i (i = 1 to n), and demultiplexes the optical single carrier signal. The optical demultiplexing unit 100 outputs to the signal receiving device 101-i (i = 1 to n) corresponding to the frequency band.

Each of the plurality of signal receiving apparatuses 101-i (i = 1 to n) demodulates the signal input from the optical demultiplexing unit 100.
The optical demultiplexing unit 100 receives the received optical single carrier so that the frequency band of the demultiplexed signal is wider than at least the frequency band demodulated by the corresponding signal receiving apparatus 101-i (i = 1 to n). The signal is demultiplexed into a signal in a frequency band demodulated by a plurality of signal receiving apparatuses 101-i (i = 1 to n).

  In this way, the pass band of the optical demultiplexing unit 100 is set wider than the signal to be demodulated, and the light is demultiplexed and demodulated by the signal receiving apparatus 101-i (i = 1 to n). As a result, the signal receiving apparatus 101-i (i = 1 to n) demodulates only symbols of frequency components necessary for demodulation.

  According to the third embodiment, the block division by the BPF, which has been performed in the electrical domain in the first and second embodiments, is also performed in the frequency domain of light using the optical demultiplexing unit 100. As a result, the requirements for circuit speed can be relaxed. In other words, it is possible to demodulate a wider-band optical single carrier signal than when the signal receiving device 101-i (i = 1 to n) is used alone.

  As the optical demultiplexing unit 100, an arrayed waveguide demultiplexer may be used, or a configuration in which an n-branching optical demultiplexing unit and an optical bandpass filter are combined may be used. Further, when the optical single carrier signal is divided into two blocks in the optical frequency domain, a combination of an optical 3 dB coupler and an optical bandpass filter is also possible.

  In the frequency conversion circuit 52-i in FIG. 2 or FIG. 9 described above, after frequency conversion is performed for each channel, the level is adjusted to a preset target value of power common to all channels, and all subcarriers are set. The reception quality of all the subcarriers can be made the same by making the signal power of the same.

  In the above description, the optical single carrier signal is received. However, the single carrier signal may be received wirelessly. In this case, the single carrier signal received via the receiving unit is input to the demodulator 5.

It is a block diagram which shows the structure of the signal receiver in the 1st Embodiment of this invention. It is a block diagram which shows the structure of the demodulator by the same embodiment. It is a figure which shows the waveform as an example of the broadband optical single carrier signal input into the embodiment. It is a figure which shows the waveform as an example of the broadband electric single carrier signal frequency-converted to IF band which the balance receiver by the same embodiment outputs to a demodulator. It is a figure which shows the frequency band as an example which BPF by the embodiment extracts from a broadband electric single carrier signal. It is a figure which shows the frequency conversion as an example by the frequency conversion circuit by the embodiment. It is a figure which shows the signal as an example which the signal selection circuit by the embodiment selected. It is a figure which shows the some block which divides the single carrier signal by the same embodiment by BPF It is a block diagram which shows the structure of the signal receiver in the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the digital signal processing part of FIG. FIG. 3 is a block diagram showing a configuration of an optoelectric conversion unit using an optical 90 ^o hybrid coupler as an example. FIG. 3 is a block diagram showing a configuration in a case where a photoelectric conversion unit using an optical 90 ^o hybrid coupler is applied to the embodiment. It is a block diagram which shows the structure of the signal receiver in the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1A ... Signal receiver 2 ... Local oscillation light source 3 ... Coupler 4 ... Balance receiver 5, 5A ... Demodulator 6 ... Optical 90 degree hybrid coupler 50 ... Branch circuit 51-1 to 51-k, 19b-1 to 19b -K, 19c-1 to 19c-k ... BPF (band pass filter)
52-1 to 52-k, 18b-1 to 18b-k, 18c-1 to 18c-k... Frequency conversion circuit (frequency conversion unit)
53-1 to 53-k, 17a-1 to 17a-k, 17b-1 to 17b-k, 17c-1 to 17c-k ... A / D conversion circuit (analog / digital conversion circuit)
54-1 to 54-k... GI removal circuit (guard interval removal unit)
55-1 to 55-k ... Fourier transform circuit (Fourier transform unit)
56-1 to 56-k: signal selection circuits 57-1 to 57-k ... equalization circuits 58-1 to 58-k: inverse Fourier transform circuit (inverse Fourier transform unit)
59-1 to 59-k ... demodulator 60 ... P / S converter (parallel serial converter)
61 ... Local oscillator 62 ... Common clock 600 ... Local oscillation light source 601 ... Optical 3dB coupler 620 ... Local oscillator

Claims (14)

A signal receiving apparatus that receives and demodulates an optical single carrier signal including a transmission signal,
The optical single carrier signal is converted into parallel transmission data by a signal transmission device, and each of the parallel-converted transmission data is modulated, Fourier-transformed, and zero in frequency outside the band so as to be oversampled. After the frequency component is inserted, inverse Fourier transform is performed, a guard interval is inserted into the inverse Fourier transformed signal, converted to a synchronized analog signal, and after frequency conversion, the signal in the frequency band is extracted and the interference part is extracted. It is a signal generated by generating a removed signal, synthesizing serially generated signals of each channel, generating a broadband optical signal corresponding to the input signal, and transmitting it as a broadband optical single carrier signal,
A branch circuit for branching the single carrier signal obtained by optical / electrical conversion of the optical single carrier signal ;
A plurality of processing units each corresponding to a channel of the single carrier signal and demodulating a transmission signal of a channel corresponding to the channel ;
A parallel-serial conversion unit that converts the transmission signal demodulated by the plurality of processing units into a serial signal and outputs the serial signal;
Have
The processing units are respectively
A bandpass filter for extracting a frequency region corresponding to the own channel from a single carrier signal branched by the branch circuit;
A frequency conversion circuit that performs frequency conversion so that the signal extracted by the bandpass filter becomes the center frequency of the frequency band used by the own channel;
An analog-to-digital conversion circuit that performs analog-to-digital conversion to a digital signal that is over-sampled and synchronized with a digital signal that is output by another processing unit, the frequency-converted signal by the frequency conversion circuit;
A Fourier transform circuit for Fourier transforming the digital signal converted by the analog-digital conversion circuit;
A signal selection circuit for selecting a digital signal predetermined as a demodulation target in the own channel from the digital signals converted by the Fourier transform circuit;
An equalization circuit for equalizing the digital signal selected by the signal selection circuit in a frequency domain;
An inverse Fourier transform circuit for inverse Fourier transforming the digital signal equalized by the equalization circuit;
A demodulation circuit that demodulates the digital signal obtained by the inverse Fourier transform by the inverse Fourier transform circuit using a predetermined demodulation method;
Have
The parallel-serial conversion unit is
A transmission signal for each channel demodulated by the plurality of demodulation circuits is converted into a serial signal;
A signal receiving device. The signal receiving device receives an optical single carrier signal;
A local oscillation light source from which the signal receiving device outputs an optical signal;
A coupler for combining the received optical single carrier signal and the light output from the local oscillation light source as an optical signal;
A balance receiver that optically / electrically converts the optical signal combined by the coupler and outputs it as an electric single carrier signal;
Have
The branch circuit is
An electric single carrier signal optical / electrically converted by the balance receiver is branched as the single carrier signal;
The signal receiving device according to claim 1. The signal receiving device is
A local oscillation light source adjustment unit that detects a frequency deviation from the digital signal demodulated by the demodulation circuit and adjusts an optical signal output from the local oscillation light source based on the detected frequency deviation;
The signal receiving apparatus according to claim 2, comprising: The processing units are respectively
The analog-to-digital conversion circuit has a guard interval removal circuit that removes a guard interval from a digital signal that has been converted from analog to digital,
The Fourier transform circuit is
The guard interval removal circuit performs Fourier transform on the signal from which the guard interval has been removed,
The signal receiving apparatus according to claim 1, wherein the signal receiving apparatus is a signal receiving apparatus. In the communication step of determining the signal position of the guard interval to be removed by the guard interval removal circuit,
The single carrier signal or optical single carrier signal is
Only one of the predetermined channels has guard interval position information indicating a signal position where the guard interval is removed,
The other channels do not interfere with the one channel,
The signal receiving device is
A guard interval position information detection unit for detecting guard interval position information included in the single carrier signal or the optical single carrier signal;
In the communication stage after the communication stage for determining the signal position of the guard interval,
The guard interval removal circuit in the plurality of processing units,
Based on the guard interval position information detected by the guard interval position information detection unit, the analog-digital conversion circuit removes the guard interval from the digital signal analog-digital converted,
The signal receiving apparatus according to claim 4. In the communication step of determining the signal position of the Fourier transform window where the Fourier transform circuit performs Fourier transform,
The single carrier signal or optical single carrier signal is
Only one of the predetermined channels has window position information indicating a signal position for detecting the window position, and
The other channels do not interfere with the one channel,
The signal receiving device is
A window position information detector for detecting window position information included in the single carrier signal or the optical single carrier signal;
In the communication stage after the communication stage for determining the signal position of the Fourier transform window,
The Fourier transform circuit in the plurality of processing units,
Based on the window position information detected by the window position information detection unit, Fourier transform the digital signal converted by the analog-digital conversion circuit or the signal from which the guard interval removal circuit has removed the guard interval,
The signal receiving device according to claim 1, wherein the signal receiving device is a signal receiving device. A signal receiving apparatus that receives and demodulates an optical single carrier signal including a transmission signal,
The optical single carrier signal is converted into parallel transmission data by a signal transmission device, and each of the parallel-converted transmission data is modulated, Fourier-transformed, and zero in frequency outside the band so as to be oversampled. After the frequency component is inserted, inverse Fourier transform is performed, a guard interval is inserted into the inverse Fourier transformed signal, converted to a synchronized analog signal, and after frequency conversion, the signal in the frequency band is extracted and the interference part is extracted. It is a signal generated by generating a removed signal, synthesizing serially generated signals of each channel, generating a broadband optical signal corresponding to the input signal, and transmitting it as a broadband optical single carrier signal,
A local oscillation light source that outputs an optical signal;
An optical 90 ° hybrid coupler that combines the received optical single carrier signal and the light output from the local oscillation light source to output optical signals of I phase and Q phase;
An I-phase balanced receiver that is a balanced receiver that converts an I-phase optical signal output by the optical 90 ° hybrid coupler into an electrical signal and outputs the signal as an I-phase single carrier signal;
A Q-phase balanced receiver that is a balanced receiver that converts a Q-phase optical signal output by the optical 90 ° hybrid coupler into an electrical signal and outputs the signal as a Q-phase single carrier signal;
A demodulator that demodulates the I-phase single carrier signal output by the I-phase balanced receiver and the Q-phase single carrier signal output by the Q-phase balanced receiver and outputs a transmission signal;
Have
The demodulator
A plurality of processing units each corresponding to a channel of the optical single carrier signal and demodulating a transmission signal of a channel corresponding to the channel;
A parallel-serial conversion unit that converts the transmission signal demodulated by the plurality of processing units into a serial signal and outputs the serial signal;
Have
The processing units are respectively
An I-phase bandpass filter that is a bandpass filter that extracts a frequency region corresponding to the own channel from an I-phase single carrier signal output by the I-phase balanced receiver;
A Q-phase bandpass filter that is a bandpass filter that extracts a frequency region corresponding to the own channel from a Q-phase single carrier signal output by the Q-phase balanced receiver;
The signal extracted by the I-phase bandpass filter and the signal extracted by the Q-phase bandpass filter are frequency-converted so as to be the center frequency of the frequency band used by the own channel, and the I-phase and Q-phase signals are converted. A frequency conversion circuit that outputs a frequency converted signal;
An I-phase analog-to-digital conversion circuit that is an analog-to-digital conversion circuit that over-samples the I-phase signal frequency-converted by the frequency conversion circuit and performs analog-to-digital conversion to a digital signal that is synchronized with a digital signal output by another processing unit; ,
A Q-phase analog-to-digital conversion circuit, which is an analog-to-digital conversion circuit that over-samples the Q-phase signal frequency-converted by the frequency conversion circuit and converts the signal into a digital signal synchronized with a digital signal output by another processing unit; ,
An I-phase Fourier transform circuit, which is a Fourier transform circuit that Fourier transforms the digital signal converted by the I-phase analog-digital conversion circuit;
A Q-phase Fourier transform circuit which is a Fourier transform circuit that Fourier-transforms the digital signal converted by the Q-phase analog-digital conversion circuit;
An I-phase signal selection circuit which is a signal selection circuit for selecting a digital signal predetermined as a demodulation target in the own channel from the digital signals converted by the I-phase Fourier transform circuit;
A Q-phase signal selection circuit which is a signal selection circuit for selecting a digital signal predetermined as a demodulation target in the own channel from the digital signals converted by the Q-phase Fourier transform circuit;
An I-phase equalization circuit for equalizing the digital signal selected by the I-phase signal selection circuit in a frequency domain;
A Q-phase equalization circuit for equalizing the digital signal selected by the Q-phase signal selection circuit in a frequency domain;
An inverse Fourier transform circuit for inverse Fourier transforming the digital signal equalized by the I-phase equalization circuit and the digital signal equalized by the Q-phase equalization circuit;
A demodulation circuit that demodulates the digital signal obtained by the inverse Fourier transform by the inverse Fourier transform circuit using a predetermined demodulation method;
Have
The parallel-serial conversion unit is
A transmission signal for each channel demodulated by the plurality of demodulation circuits is converted into a serial signal;
A signal receiving device. The signal receiving device is
A local oscillation light source adjustment unit that detects a frequency deviation from the digital signal demodulated by the demodulation circuit and adjusts an optical signal output from the local oscillation light source based on the detected frequency deviation;
The signal receiving apparatus according to claim 7, comprising: The processing units are respectively
An I-phase guard interval removal circuit, which is a guard interval removal circuit that removes a guard interval from the digital signal analog-digital converted by the I-phase analog-digital conversion circuit;
A Q-phase guard interval removal circuit, which is a guard interval removal circuit that removes a guard interval from the digital signal analog-digital converted by the Q-phase analog-digital conversion circuit;
Have
The I-phase Fourier transform circuit is
The I-phase guard interval removing circuit Fourier-transforms the signal from which the guard interval is removed,
The Q-phase Fourier transform circuit is
The Q phase guard interval removal circuit performs Fourier transform on the signal from which the guard interval has been removed.
The signal receiving apparatus according to claim 7 or 8, wherein In the communication step of determining the signal position of the guard interval to be removed by the guard interval removal circuit,
The single carrier signal or optical single carrier signal is
Only one of the predetermined channels has guard interval position information indicating a signal position where the guard interval is removed,
The other channels do not interfere with the one channel,
The signal receiving device is
A guard interval position information detection unit for detecting guard interval position information included in the single carrier signal or the optical single carrier signal;
In the communication stage after the communication stage for determining the signal position of the guard interval,
The I-phase guard interval removal circuit in the plurality of processing units,
Based on the guard interval position information detected by the guard interval position information detection unit, the guard interval is removed from the digital signal analog-digital converted by the I-phase analog-digital conversion circuit,
A Q-phase guard interval removal circuit in the plurality of processing units,
Based on the guard interval position information detected by the guard interval position information detection unit, the Q phase analog-digital conversion circuit removes the guard interval from the digital signal analog-digital converted,
The signal receiving device according to claim 9. In the communication step of determining the signal position of the Fourier transform window where the Fourier transform circuit performs Fourier transform,
The single carrier signal or optical single carrier signal is
Only one of the predetermined channels has window position information indicating a signal position for detecting the window position, and
The other channels do not interfere with the one channel,
The signal receiving device is
A window position information detector for detecting window position information included in the single carrier signal or the optical single carrier signal;
In the communication stage after the communication stage for determining the signal position of the Fourier transform window,
An I-phase Fourier transform circuit in the plurality of processing units,
Based on the window position information detected by the window position information detector, the digital signal converted by the I-phase analog-digital conversion circuit or the signal from which the I-phase guard interval removal circuit has removed the guard interval is Fourier transformed,
A Q-phase Fourier transform circuit in the plurality of processing units,
Based on the window position information detected by the window position information detection unit, the digital signal converted by the Q-phase analog-to-digital conversion circuit or the signal from which the Q-phase guard interval removal circuit has removed the guard interval is Fourier transformed.
The signal receiving apparatus according to claim 7, wherein the signal receiving apparatus is a signal receiving apparatus. A signal receiving system comprising a plurality of signal receiving devices according to any one of claims 2 to 11,
The plurality of signal receiving devices are preset so as to demodulate channels of different frequency bands,
The signal receiving system is
An optical demultiplexing unit that demultiplexes the received optical single carrier signal into a channel of a frequency band demodulated by the plurality of signal receiving apparatuses and outputs the demultiplexed optical single carrier signal to the signal receiving apparatus corresponding to the frequency band Have
Each of the plurality of signal receiving devices,
Demodulate the optical single carrier signal of the channel input from the optical demultiplexing unit,
A signal receiving system. The optical demultiplexing unit is
Channels in the frequency band in which the plurality of signal receiving devices demodulate the received optical single carrier signal so that the frequency band of the demultiplexed channel is at least wider than the frequency band in which the corresponding signal receiving device demodulates. To demultiplex,
The signal receiving system according to claim 12. A signal receiving method used in a signal receiving apparatus that receives and demodulates an optical single carrier signal including a transmission signal,
The optical single carrier signal is converted into parallel transmission data by a signal transmission device, and each of the parallel-converted transmission data is modulated, Fourier-transformed, and zero in frequency outside the band so as to be oversampled. After the frequency component is inserted, inverse Fourier transform is performed, a guard interval is inserted into the inverse Fourier transformed signal, converted to a synchronized analog signal, and after frequency conversion, the signal in the frequency band is extracted and the interference part is extracted. It is a signal generated by generating a removed signal, synthesizing serially generated signals of each channel, generating a broadband optical signal corresponding to the input signal, and transmitting it as a broadband optical single carrier signal,
A branching procedure for branching the optically / electrically converted single carrier signal from the optical single carrier signal;
A plurality of processing procedures each corresponding to a channel of the single carrier signal and demodulating a transmission signal of a channel corresponding to the channel ;
A parallel-serial conversion procedure for converting the transmission signal demodulated in the plurality of processing procedures into a serial signal and outputting the serial signal;
Have
Each of the processing procedures is
A bandpass filter procedure for extracting a frequency region corresponding to the own channel from the single carrier signal branched in the branching procedure;
A frequency conversion procedure for performing frequency conversion so that the signal extracted by the bandpass filter procedure becomes the center frequency of the frequency band used by the own channel;
An analog-to-digital conversion procedure for analog-to-digital conversion of the signal frequency-converted in the frequency conversion procedure into a digital signal that is oversampled and synchronized with a digital signal output by another processing procedure;
Fourier transform procedure for Fourier transforming the digital signal converted by the analog-digital conversion procedure;
From the digital signal converted by the Fourier transform procedure, a signal selection procedure for selecting a digital signal predetermined as a demodulation target in its own channel;
An equalization procedure for equalizing the digital signal selected in the signal selection procedure in the frequency domain;
An inverse Fourier transform procedure for performing an inverse Fourier transform on the digital signal equalized by the equalization procedure;
Demodulation procedure for demodulating the digital signal inverse Fourier transformed by the inverse Fourier transform procedure by a predetermined demodulation method;
Have
The parallel serial conversion procedure is:
Converting a transmission signal for each channel demodulated by the plurality of demodulation procedures into a serial signal;
And a signal receiving method.

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