Reception device, transmission device, optical communication system and optical communication method
A reception device 20 is configured to include a separation means 21 and a plurality of optical reception means 22 . Each optical reception means 22 further includes an optical/electrical conversion means 23 , a reception coefficient computation means 24 , and a band restoration means 25 . The separation means 21 separates a multiplexed signal into which signals of respective channels to which spectral shaping that narrows bandwidth to less than or equal to a baud rate is applied as band narrowing filter processing on the transmission side, based on characteristics of a transmission line are multiplexed at spacings less than or equal to the baud rate. Each band restoration means 25 applies processing having inverse characteristics to those of the band narrowing filter processing to a reception signal, based on the band narrowing parameter acquired by the reception coefficient computation means 24 and thereby restores the band of the reception signal.
1. A reception device comprising:
a demultiplexer which receives a multiplexed signal into which signals of respective channels to which spectral shaping that narrows bandwidth to less than or equal to a baud rate is applied as band narrowing filter processing on a transmission device, based on a band narrowing parameter that, based on characteristics of a transmission line transmitting optical signals, is set as a parameter indicating a degree of bandwidth narrowing of a signal are wavelength-division-multiplexed at spacings less than or equal to the baud rate and separates the multiplexed signal into the optical signals for the respective channels; and
a plurality of optical receivers each of which comprises an optical/electrical converter which acquires, as a wavelength-division-multiplexing spacing parameter, information of center wavelengths of the optical signals for the respective channels and a spacing between the center wavelengths that are set based on characteristics of the transmission line, converts the optical signal of the assigned channel to an electrical signal, based on the wavelength-division-multiplexing spacing parameter, and outputs the electrical signal as a reception signal, a reception coefficient computer which acquires the band narrowing parameter and, based on the band narrowing parameter, computes a filter coefficient when processing having inverse characteristics to those of the band narrowing filter processing applied on the transmission device is applied to the reception signal as band restoration filter processing, and a band restorer which applies the band restoration filter processing to the reception signal, based on the filter coefficient computed by the reception coefficient computer and thereby restores a band of the reception signal.
2. The reception device according to claim 1 , wherein
the band narrowing parameter is set as a band narrowing factor that indicates a ratio of a bandwidth after the band narrowing filter processing to a bandwidth matching a baud rate.
3. The reception device according to claim 1 further comprising
a noise measurer which measures a signal-to-noise ratio of the optical signal received via the transmission line and transmits information of the signal-to-noise ratio, wherein
each reception coefficient computer acquires the band narrowing parameter that is set using information of the signal-to-noise ratio as characteristics of the transmission line from a transmission destination of information of the signal-to-noise ratio.
4. The reception device according to claim 1 further comprising
a spectrum acquirer which acquires a signal spectrum of the optical signal received via the transmission line and transmits information of the signal spectrum, wherein
each reception coefficient computer acquires the band narrowing parameter that is set based on characteristics of the transmission line extracted from information of the signal spectrum from a transmission destination of information of the signal spectrum.
5. The reception device according to claim 4 , wherein
the spectrum acquirer monitors linear equalization processing of the reception signal and acquires the signal spectrum.
6. The reception device according to claim 1 , wherein
each optical/electrical converter makes local oscillator light having a wavelength based on the wavelength-division-multiplexing spacing parameter and the optical signal input from the separation unit interfere with each other and thereby performs coherent detection.
7. The reception device according to claim 1 , wherein
the demultiplexer acquires the wavelength-division-multiplexing spacing parameter and separates the multiplexed signal into optical signals for the respective channels, based on the wavelength-division-multiplexing spacing parameter.
8. An optical communication system comprising:
a transmission device which comprises
a plurality of optical transmitters each of which comprises a transmission coefficient computer which acquires a parameter indicating a degree of bandwidth narrowing when spectral shaping that narrows bandwidth of a signal to less than or equal to a baud rate is performed, as a band narrowing parameter that is set based on characteristics of a transmission line transmitting optical signals and computes a filter coefficient when processing of narrowing the bandwidth of the signal is applied as band narrowing filter processing, a band narrowing unit which, based on the filter coefficient computed by the transmission coefficient computer, applies processing of narrowing the bandwidth of the signal as band narrowing filter processing, and an electrical/optical converter which acquires, as a wavelength-division-multiplexing spacing parameter, information of center wavelengths of the optical signals for respective channels and a spacing between the center wavelengths that are set based on characteristics of the transmission line and converts the signal the bandwidth of which is narrowed to less than or equal to the baud rate by the band narrowing unit to the optical signal, based on the wavelength-division-multiplexing spacing parameter; and
a multiplexer which multiplexes the optical signals of the channels output from the plurality of optical transmitters into a multiplexed signal, at spacing less than or equal to the baud rate and outputs the multiplexed signal to the transmission line;
a reception device according to claim 1 ; and
a communication controller which comprises a parameter computer which, based on information of pathways of a transmission line for optical signals and characteristics of the transmission line, computes a band narrowing parameter that indicates information of bandwidth when spectral shaping that narrows the bandwidth to less than or equal to a baud rate is applied to signals of respective channels and a wavelength-division-multiplexing spacing parameter that indicates center wavelengths of the optical signals for the respective ones of a plurality of the channels and a wavelength spacing between the center wavelengths; and
a parameter transmitter which transmits the band narrowing parameter and the wavelength-division-multiplexing spacing parameter to both the transmission device and the reception device of the optical signals, wherein the communication controller transmits the band narrowing parameter and the wavelength-division-multiplexing spacing parameter to both the transmission device and the reception device,
the transmission device receives the band narrowing parameter and the wavelength-division-multiplexing spacing parameter form the communication controller, converts signals to which the band narrowing filter processing is applied based on the band narrowing parameter to the optical signals, based on the wavelength-division-multiplexing spacing parameter, and multiplexes the optical signals of a plurality of the channels into the multiplexed signal and transmits the multiplexed signal to the transmission line, and
the reception device receives the band narrowing parameter and the wavelength-Division-multiplexing spacing parameter from the communication controller, converts the optical signals into which the multiplexed signal received from the transmission device via the transmission line are separated to electrical signals, based on the wavelength-division-multiplexing spacing parameter, and applies the band restoration filter processing to reception signals that have been converted to the electrical signals, based on the band narrowing parameter.
9. A transmission device comprising:
a plurality of optical transmitters each of which comprises a transmission coefficient computer which acquires a parameter indicating a degree of bandwidth narrowing when spectral shaping that narrows bandwidth of a signal to less than or equal to a baud rate is performed, as a band narrowing parameter that is set based on characteristics of a transmission line transmitting optical signals and computes a filter coefficient when processing of narrowing the bandwidth of the signal is applied as band narrowing filter processing, a band narrowing unit which, based on the filter coefficient computed by the transmission coefficient computer, applies processing of narrowing the bandwidth of the signal as band narrowing filter processing, and an electrical/optical converter which acquires, as a wavelength-division-multiplexing spacing parameter, information of center wavelengths of the optical signals for respective channels and a spacing between the center wavelengths that are set based on characteristics of the transmission line and converts the signal, the bandwidth of which is narrowed to less than or equal to the baud rate by the band narrowing unit to the optical signal, based on the wavelength-division-multiplexing spacing parameter; and
a multiplexer which multiplexes the optical signals of the channels output from the plurality of optical transmitters into a multiplexed signal, at spacings less than or equal to the baud rate and outputs the multiplexed signal to the transmission line.
10. The transmission device according to claim 9 , wherein
the band narrowing parameter is set as a band narrowing factor that indicates a degree of band narrowing in the band narrowing filter processing.
11. The transmission device according to claim 9 , wherein
the multiplexer acquires, as the wavelength-division-multiplexing spacing parameter, information of a wavelength spacing between the optical signals when the optical signals that the plurality of optical transmission units generated are multiplexed and multiplexes the optical signals at wavelength spacings based on the wavelength-division-multiplexing spacing parameter.
12. An optical communication method comprising:
separating a multiplexed signal into which signals of respective channels to which spectral shaping that narrows bandwidth of a signal to less than or equal to a baud rate is applied as band narrowing filter processing, based on a band narrowing parameter that, based on characteristics of a transmission line transmitting optical signals, is set as a parameter indicating a degree of bandwidth narrowing of a signal are multiplexed at spacings less than or equal to the baud rate into optical signals for the respective channels;
acquiring information of center wavelengths of optical signals for the respective channels and a spacing between the center wavelengths that are set based on characteristics of a transmission line, as a wavelength-division-multiplexing spacing parameter, converting the optical signals of the assigned channels to electrical signals, based on the wavelength-division-multiplexing spacing parameter, and outputting the electrical signals as reception signals,
acquiring the band narrowing parameter and, based on the band narrowing parameter, computing a filter coefficient when processing having inverse characteristics to those of the band narrowing filter processing is applied to the reception signals as band restoration filter processing, and
applying the band restoration filter processing to the reception signals, based on the computed filter coefficient and thereby restoring bands of the reception signals.
13. The optical communication method according to claim 12 , wherein
the band narrowing parameter is set as a band narrowing factor that indicates a degree of band narrowing in the band narrowing filter processing.
14. The optical communication method according to claim 12 further comprising:
measuring signal-to-noise ratios of the optical signals received via the transmission line and transmitting information of the signal-to-noise ratios, wherein
the band narrowing parameter that is set using information of the signal-to-noise ratios as characteristics of the transmission line is acquired from a transmission destination of information of the signal-to-noise ratios.
15. The optical communication method according to claim 12 further comprising:
acquiring signal spectra of the optical signals received via the transmission line and transmitting information of the signal spectra, wherein
the band narrowing parameter that is set based on characteristics of the transmission line extracted from information of the signal spectra is acquired from a transmission destination of information of the signal spectra.
16. The optical communication method according to claim 15 , wherein
the signal spectra is acquired by monitoring linear equalization processing of the reception signals.
17. The optical communication method according to claim 12 further comprising:
making local oscillator light having wavelengths based on the wavelength-division-multiplexing spacing parameter and the optical signal separated from the multiplexed signal interfere with each other and thereby performing coherent detection.
18. The optical communication method according to claim 12 , wherein
the multiplexed signal is separated into optical signals for the respective channels, based on the wavelength-division-multiplexing spacing parameter.
19. The optical communication method according to claim 12 further comprising:
acquiring a parameter indicating a degree of bandwidth narrowing when spectral shaping that narrows bandwidth of a signal to less than or equal to a baud rate is performed, as the band narrowing parameter that is set based on characteristics of a transmission line transmitting optical signals;
computing a filter coefficient when processing of narrowing the bandwidth of the signals is applied as the band narrowing filter processing;
applying processing of narrowing the bandwidth of the signals as the band narrowing filter processing, based on the computed filter coefficient;
acquiring, as the wavelength-division-multiplexing spacing parameters, information of center wavelengths of optical signals for the respective channels and a spacing between the center wavelengths that are set based on characteristics of the transmission line;
converting the signals, the bandwidth of which is narrowed to less than or equal to the baud rate to the optical signals, based on the wavelength-division-multiplexing spacing parameter; and
multiplexing the optical signals of a plurality of the channels into a multiplexed signal at spacings less than or equal to the baud rate and outputting the multiplexed signal to the transmission line.
20. The optical communication method according to claim 19 , wherein
the band narrowing parameter is set as a band narrowing factor that indicates a degree of band narrowing in the band narrowing filter processing.