JP6030027B2 - Optical transmission system - Google Patents

Description

  The present invention relates to an optical network system using a digital coherent system that performs digital signal processing. In particular, the present invention relates to an optical transmission system that branches and transmits the same signal into a plurality of optical signals, combines them after reception, and restores the transmitted signals.

  In an ultra-high-speed transmission system with a transmission rate per wavelength of 100 Gbit / s or more, a digital coherent technology combining a coherent optical communication technology and a digital signal processing technology has been widely used. The DP-QPSK (Dual Polarization-Quadrature Phase Shift Keying) method, which is standard as a modulation / demodulation method in 100 Gbit / s long-distance optical transmission systems, multiplexes 32 Gbit / s signals by using four-level phase modulation. Thus, a coherent optical signal is generated and further multiplexed by using two polarizations to generate a 128 Gbit / s coherent optical signal. On the receiving side, the signal coherently detected using local light having the same wavelength as that of the signal light is digitized using an A / D converter, and then clock extraction, frequency offset compensation, and transmission path are performed by digital signal processing using a DSP. Excellent transmission characteristics are realized by performing chromatic dispersion compensation, polarization dispersion compensation, separation of polarization signals, and the like.

  In addition, as a network using 100 Gbit / s signals, an optical signal output from an optical transmitter collides with other wavelengths in an arbitrary path (Directionless) at an arbitrary wavelength (Colorless) in one wavelength unit. A CDC-ROADM network using an optical cross-connect (XC) device that realizes a CDC function that can be switched without (Contentionless) has been studied (Non-Patent Document 1). In the CDC-ROADM network, in addition to the conventional protection using two paths, the optical signal is switched to the third backup route using the CDC function to ensure the reliability of the network even in the event of a catastrophic disaster. It becomes possible.

Prasanna, G .; Kishore, BS; Omprasad, GK; Raju, KS; Gowrishankar, R .; Venkataramaniah, K .; Johnson, R .; Voruganti, P., “Versatility of a colorless and directionless WSS based ROADM architecture”, Communication Systems and Networks and Workshops, Jan. 2009 Page (s): 1-8, (2009). H.Y.Choi, T.Tsuritani, and I.Morita, “BER-adaptive flexible-format transmitter for elastic optical networks,” Optics Express, vol.20, no.17, pp.18652-18658, 2012.

  As a further large-capacity transmission system, combined use of multi-value modulation signals and multiplexing using a plurality of wavelengths such as 16QAM (Quadratuere Amplitude Modulation) has been studied. However, since the reception sensitivity is lowered due to the multi-level modulation signal, the transmission distance is limited (Non-Patent Document 2).

  Further, in the case of switching using the CDC function, it takes about several seconds to physically switch the optical switch constituting the optical XC apparatus, and the optical signal is interrupted during that time.

  It is an object of the present invention to provide a stable optical transmission system that improves transmission characteristics using digital signal processing and that does not cause an optical signal interruption when an optical network failure occurs.

The optical transmission system of the first invention replicates the data signal d by the number of wavelengths m × the number of optical transmission lines n (m is an integer greater than or equal to 2, n is an integer greater than or equal to 2), and each delay unit gives a predetermined delay. An optical signal transmitter that sets and converts n optical signals for each wavelength, and wavelength-multiplexes m-wave optical signals to generate n wavelength-multiplexed optical signals, which are output to n optical transmission lines, respectively. The optical XC device 1 and the optical XC device 2 that receives n wavelength-multiplexed optical signals transmitted through the n optical transmission lines and demultiplexes them into m-wave optical signals are separated by the optical XC device 2. An optical signal receiving device including a MIMO processing circuit that receives a waved m × n wave optical signal, converts it into an electrical signal, and performs (m × n) × m MIMO processing, and replicated data signal The transmission delay difference in n optical transmission lines of d is roughly adjusted by a delay device, and the signal processing in the MIMO processing circuit Adjustment to a structure for combining a data signal d.

The optical transmission system according to the second aspect of the invention receives s data signals d1 to ds (s is an integer of 2 or more), and each data signal d1 to ds has a wavelength different from each other, the number of wavelengths m × optical transmission. An optical signal transmitting device that replicates the number of paths n (m is an integer of 1 or more, n is an integer of 2 or more), sets a predetermined delay in each delay unit, and converts it into n optical signals for each wavelength; An optical XC device 1 that multiplexes m × s-wave optical signals to generate n wavelength-multiplexed optical signals and outputs them to the n optical transmission lines, and n transmitted through the n optical transmission lines. An optical XC device 2 that receives a wavelength-division multiplexed optical signal and demultiplexes the optical signal into an m × s optical signal, and receives an m × s optical signal that is demultiplexed by the optical XC device 2 and receives an electrical signal. And a MIMO processing circuit that performs (m × n) × m MIMO processing for each of the same data signals d1 to ds. An optical signal receiving device, and the transmission delay difference in the n optical transmission lines of the data signal replicated for each of the data signals d1 to ds is coarsely adjusted by a delay device and finely adjusted by signal processing in the MIMO processing circuit Thus, the data signals d1 to ds are combined.

  In the optical transmission system of the first invention or the second invention, the optical signal is received by the optical signal receiving device according to the delay amount of the data signal converted and synthesized from the optical signal of each wavelength transmitted through the optical transmission line. In this configuration, the delay amount set in the delay unit of the transmission apparatus is controlled.

  In the optical transmission system of the second invention, priorities are set for the data signals d1 to ds, and a failure occurs in any of the n optical transmission lines, and wavelength division multiplexing from the optical transmission line is performed in the optical signal receiving apparatus. When no optical signal is input, the optical signal transmitting device and the optical signal receiving device allocate the wavelength assigned to the low priority data signal to the high priority data signal, and transmit (m × n) × m. In this configuration, a high-priority data signal is synthesized by performing the MIMO process.

  In the optical signal transmitter, the optical signal transmitter roughly adjusts the delay amount of the duplicated optical signals, transmits the optical signals by the optical signal receiver, and then receives them by the MIMO processing. Transmission characteristics can be improved by finely adjusting the delay amount between signals and synthesizing the signals. Further, it is possible to realize a stable optical transmission system in which an optical signal is not interrupted when an optical transmission path failure occurs.

It is a figure which shows Example 1 of the optical transmission system of this invention. It is a figure which shows Example 2 of the optical transmission system of this invention. It is a figure which shows Example 3 of the optical transmission system of this invention. It is a figure which shows Example 5 of the optical transmission system of this invention. It is a figure which shows Example 6 of the optical transmission system of this invention. 2 is a diagram illustrating a configuration example of an optical transmitter 15. FIG. 3 is a diagram illustrating a configuration example of an optical receiver 25. FIG. 1 is a diagram illustrating a configuration example used in an experiment of an optical transmission system of Example 1. FIG. It is a figure which shows the constellation after the digital signal processing of DP-QPSK signal.

FIG. 1 shows a first embodiment of the optical transmission system of the present invention.
In FIG. 1, an optical signal transmission apparatus 10 distributes a client signal receiver 11 that outputs a received client signal as a data signal d, and distributes the data signal d in three to transmit at three wavelengths (m = 3). The ODU-XC 12 to be output, the error correction encoder 13 for performing error correction encoding on each of the three identical data signals d and further distributing and outputting them in two directions (n = 2), and the total The delay unit 14 adjusts the delay of six identical data signals, and the optical transmitter 15 outputs two identical six delay-adjusted data signals as optical signals having wavelengths λ1 to λ3. The Note that the order of the delay unit 14 and the error correction encoder 13 may be switched, and the function of the error correction encoder 13 may be included in the optical transmitter 15. In this case, the ODU-XC 12 is configured to distribute the data signal d into six and input to each delay unit 14. The same applies to the configuration of the embodiment described below.

  The optical signals having the wavelengths λ1 to λ3 output from the optical signal transmission device 10 are combined by the optical XC device 17 with the wavelength-multiplexed optical signals of 2 sets to 3 wavelengths and transmitted to the optical transmission lines 51 and 52. The wavelength multiplexed optical signals transmitted through the optical transmission lines 51 and 52 are demultiplexed into optical signals having wavelengths λ1 to λ3 by the optical XC device 27 and input to the optical signal receiving device 20, respectively.

  The optical signal receiver 20 coherently detects the optical signals of wavelengths λ1 to λ3 transmitted through the optical transmission paths 51 and 52, and outputs the data signal transmitted through the three wavelengths of two paths. The (3 × 2) × 3 MIMO processing is performed on the 3 × 2 identical data signals, the MIMO processor 24 that outputs the three data signals, and the three data signals are each subjected to error correction decoding to obtain the data signal d. An error correction decoder 23 for outputting, an ODU-XC 22 for outputting any one of the three data signals d subjected to error correction decoding, and a client signal transmitter 21 for transmitting the data signal d as a client signal. Is done.

  In the first embodiment, one data signal d is transmitted through two paths of three wavelengths, and the transmission delay for each of the optical transmission paths 51 and 52 is coarsely adjusted by the delay device 14 of the optical signal transmission apparatus 10, and the optical signal is transmitted. In this configuration, the MIMO processor 24 of the signal receiving device 20 synthesizes the data signal d with fine adjustment by (3 × 2) × 3 MIMO processing. In this combining, since the combining is performed while maintaining the electric field information of the optical signal, the reception sensitivity can be improved by the effect of averaging the optical noise.

  Here, as shown in FIG. 6, the optical transmitter 15 includes a waveform equalizer 151 that performs waveform equalization by digital signal processing, a D / A converter 152 that converts the waveform-equalized digital signal into an analog signal, The coherent optical transmitter 153 converts an analog signal into an optical signal having a wavelength λi.

  As shown in FIG. 7, the optical receiver 25 includes a coherent optical receiver 251 that coherently detects an optical signal having a wavelength λi, an A / D converter 252 that converts the analog signal into a digital signal, and digital signal processing through digital signal processing. The waveform equalizer 253 outputs the waveform after equalization.

  Note that the configurations of the optical transmitter 15 and the optical receiver 25 are appropriately parallelized by modulation / demodulation methods and parallelization of signal processing. For example, when the modulation / demodulation method is a polarization multiplexing multi-level phase modulation method, each of the D / A converters 152 and the A / D converters 252 has a total of four for the IQ component of the phase modulation and for the x-Y polarization. A DP-QPSK transmitter and a DP-QPSK receiver including a D / A converter and an A / D converter are used.

FIG. 2 shows a second embodiment of the optical transmission system of the present invention.
In FIG. 2, the optical signal transmission device 10 divides the data signal d into three data signals d1 to d3 after mapping the client signal receiver 11 that outputs the received client signal as the data signal d and the data signal d to the OTN signal ( s = 3) OTN framer 16, ODU-XC 12 through data signals d 1 to d 3, and data signals d 1 to d 3 are each subjected to error correction coding and further transmitted in two directions (n = 2). An error correction encoder 13 for distributing and outputting, a delay unit 14 for adjusting the delay of each of the two data signals d1 to d3 subjected to error correction encoding, and each of the two data signals d1 to d3 subjected to the delay adjustment Are transmitted as optical signals (m = 1) having wavelengths λ1 to λ3, respectively. In this configuration, the ODU-XC 12 may be omitted.

  The optical signals having the wavelengths λ1 to λ3 output from the optical signal transmission device 10 are combined by the optical XC device 17 with the wavelength-multiplexed optical signals of 2 sets to 3 wavelengths and transmitted to the optical transmission lines 51 and 52. The wavelength multiplexed optical signals transmitted through the optical transmission lines 51 and 52 are demultiplexed into optical signals having wavelengths λ1 to λ3 by the optical XC device 27 and input to the optical signal receiving device 20, respectively.

  The optical signal receiving apparatus 20 coherently detects optical signals of wavelengths λ1 to λ3 transmitted through the optical transmission paths 51 and 52, and outputs the same data signal transmitted through one wavelength and two paths, respectively. The 1 × 2 identical data signals are subjected to (1 × 2) × 1 MIMO processing, the MIMO processor 24 for outputting the data signals d1 to d3, and the data signals d1 to d3 are each subjected to error correction decoding and output. Error correction decoder 23, ODU-XC 22 through which error corrected and decoded data signals d1 to d3 pass, OTN framer 26 which combines data signals d1 to d3 as data signal d, and combined data signal d Is transmitted as a client signal. In this configuration, the ODU-XC 22 may be omitted.

  In the second embodiment, one data signal d is divided into data signals d1 to d3 and transmitted through one wavelength and two paths (total of three wavelengths and two paths), and transmission delay for each of the optical transmission lines 51 and 52 is performed. Are coarsely adjusted by the delay unit 14 of the optical signal transmitting apparatus 10, and finely adjusted by the (1 × 2) × 1 MIMO processing for each identical data signal by the MIMO processor 24 of the optical signal receiving apparatus 20, and the data signals d1 to d3 It is the composition which synthesizes. In this combining, since the combining is performed while maintaining the electric field information of the optical signal, the reception sensitivity can be improved by the effect of averaging the optical noise.

FIG. 3 shows Embodiment 3 of the optical transmission system of the present invention.
In FIG. 3, the optical signal transmission apparatus 10 includes a client signal receiver 11 that outputs received client signals as data signals D1 and D2, and two data signals d1 to d1 after mapping the data signals D1 and D2 to OTN signals. The OTN framer 16 that outputs as d2 (s = 2) and the ODU-XC12 that distributes and outputs the data signals d1 to d2 in two wavelengths (m = 2), respectively, are output in two. Each of the data signals d1 to d2 is subjected to error correction coding, and further divided into two for transmission in two directions (n = 2), and the error correction encoder 13 for outputting the data, and each of the two pieces of error correction coded data The delay device 14 that performs delay adjustment of the signals d1 to d2 and the two data signals d1 that have been subjected to delay adjustment are output as optical signals having wavelengths λ1 to λ2, respectively. The optical transmitter 15 outputs the data signal d2 as optical signals having wavelengths λ3 to λ4, respectively.

  The optical signals having the wavelengths λ1 to λ4 output from the optical signal transmitter 10 are combined by the optical XC device 17 into the wavelength-division multiplexed optical signals of two sets and four wavelengths and transmitted to the optical transmission lines 51 and 52. The wavelength multiplexed optical signals transmitted through the optical transmission lines 51 and 52 are demultiplexed into optical signals having wavelengths λ1 to λ4 by the optical XC device 27 and input to the optical signal receiving device 20, respectively.

  The optical signal receiver 20 coherently detects the optical signals of wavelengths λ1 to λ4 transmitted through the optical transmission paths 51 and 52, and outputs the same data signal transmitted through two paths of two wavelengths, respectively. The 2 × 2 identical data signals are subjected to (2 × 2) × 2 MIMO processing, the MIMO processor 24 for outputting the data signals d1 to d2, and the error correction decoding of the data signals d1 to d2, respectively. An error correction decoder 23, an ODU-XC 22 that outputs one of the data signals d1 to d2 subjected to error correction decoding, an OTN framer 26 that converts the data signals d1 to d2 into data signals D1 and D2, and The client signal transmitter 21 transmits the data signals D1 and D2 as client signals.

  In the third embodiment, one data signal d is divided into data signals d1 to d2 and transmitted through two paths with two wavelengths (a total of four paths with two paths), and transmission delay for each of the optical transmission paths 51 and 52 is performed. Are roughly adjusted by the delay unit 14 of the optical signal transmitting apparatus 10, and finely adjusted by the (2 × 2) × 2 MIMO processing for each identical data signal by the MIMO processor 24 of the optical signal receiving apparatus 20, and the data signals d1 to d2 It is the composition which synthesizes. In this combining, since the combining is performed while maintaining the electric field information of the optical signal, the reception sensitivity can be improved by the effect of averaging the optical noise.

  In the configurations of the first to third embodiments, when the optical signal transmission device 10 and the optical signal reception device 20 are arranged in both directions, the optical transmission lines 51 and 52 are transmitted by one optical signal reception device 20. The delay amount set in the delay device 14 of one optical signal transmission device 10 may be controlled according to the delay amount of the data signal converted and combined from the optical signal of each wavelength.

  In the fifth embodiment, in the configuration of the third embodiment shown in FIG. 3, even if one of the optical transmission paths 51 and 52 fails, the other optical transmission path is functioned by the function of the MIMO processing unit 24. An example in which the data signals d1 to d2 are synthesized from the wavelength multiplexed optical signal transmitted via the line 51 is shown.

FIG. 4 shows Embodiment 5 of the optical transmission system of the present invention.
4, each of the data signals d1 to d2 generated in the same manner as in the third embodiment of FIG. 3 is transmitted through two wavelengths and one path (a total of four wavelengths and one path). The transmission delay is coarsely adjusted by the delay unit 14 of the optical signal transmitting apparatus 10, and the data signal d1 is finely adjusted by the (2 × 1) × 2 MIMO processing for each identical data signal by the MIMO processor 24 of the optical signal receiving apparatus 20. It is the structure which synthesize | combines -d2. Here, because of the failure of the optical transmission line 52, the data sensitivity decreases in the MIMO processing unit 24 from the two wavelength two paths in the third embodiment to the two wavelength one path per data signal. For example, the data signals d1 to d2 can be transmitted.

  In the sixth embodiment, in order to maintain the reception sensitivity equivalent to the two-wavelength two-path of the third embodiment per data signal, the data signal d1 is limited to four wavelengths according to the priority of the data signals d1 to d2. An example in which the transmission form of one route is taken is shown.

FIG. 5 shows Embodiment 6 of the optical transmission system of the present invention.
In FIG. 5, the optical signal transmitting apparatus 10 includes a client signal receiver 11 that outputs received client signals as data signals D1 and D2, and two data signals d1 to d1 after mapping the data signals D1 and D2 to OTN signals. OTN framer 16 that outputs as d2 (s = 2), ODU-XC12 that distributes and outputs four data signals d1 to d2 in order to transmit only the data signal d1 having a higher priority among four wavelengths, and four distributions The error correction encoder 13 that outputs the error-corrected encoded data signal d1 after error correction, the delay 14 that adjusts the delay of the error-corrected encoded data signal d1, and the wavelength of the delay-adjusted data signal d1. It comprises an optical transmitter 15 that outputs optical signals of λ1 to λ4.

  The optical signals having wavelengths λ1 to λ4 output from the optical signal transmitter 10 are combined by the optical XC device 17 into two sets and four wavelengths of wavelength multiplexed optical signals and transmitted to the optical transmission lines 51 and 52. Here, a failure has occurred in the optical transmission line 52. The wavelength multiplexed optical signal transmitted through the optical transmission path 51 is demultiplexed into optical signals having wavelengths λ1 to λ4 by the optical XC device 27 and input to the optical signal receiving device 20.

  The optical signal receiver 20 coherently detects the optical signals having wavelengths λ1 to λ4 transmitted through the optical transmission path 51, and outputs the same data signal transmitted through the four wavelengths and one path. A MIMO processor 24 that performs (4 × 1) × 4 MIMO processing for each 4 × 1 identical data signal and outputs the data signal d 1, and an error correction decoder 23 that performs error correction decoding and output of the data signal d 1, respectively. ODU-XC 22 that outputs any one of the four data signals d1 that have been subjected to error correction decoding, the OTN framer 26 that outputs the data signal d1 as the data signal D1, and the data signal D1 transmitted as a client signal The client signal transmitter 21 is configured.

  The failure of the optical transmission path 52 is detected by the optical XC device 26 and notified to the control device 31, and path settings corresponding to the ODU-XC 12 of the optical signal transmission device 10 and the ODU-XC 22 of the optical signal reception device 20 are set. Done. In the case of the fifth embodiment, nothing is done because the configuration of the MIMO processing unit 24 absorbs the failure of the optical transmission path, but in the case of the sixth embodiment, the transmission is limited to the data signal d1 only. As shown in FIG. 5, the transmission of the data signal d2 is stopped and the path of the data signal d1 is set.

  Thus, when the initial transmission characteristics cannot be maintained as in the fifth embodiment due to the occurrence of a failure in the optical transmission line, the surviving data with high priority as in the sixth embodiment Transmission characteristics can be maintained by preferentially assigning paths and wavelengths.

(Experimental example)
FIG. 8 illustrates a configuration example used in the experiment of the optical transmission system according to the first embodiment.
In FIG. 8, an optical signal transmission device 60 includes a signal generator 61 that outputs three identical data signals (pseudorandom pattern 128 Gbit / s signal), and a delayer 62 that performs delay adjustment of the three identical data signals. The DP-QPSK transmitter 63 outputs the three delay-adjusted identical data signals as the DP-QPSK optical signal having the wavelength λ1. That is, the number of wavelengths m = 1 and the number of optical transmission lines n = 3.

  The three DP-QPSK optical signals of wavelength λ1 output from the optical signal transmission device 60 are sent to the optical transmission lines 1 to 3, respectively. The wavelength multiplexed optical signal transmitted through the optical transmission lines 1 to 3 is input to the optical signal receiving device 70. Here, the optical transmission lines 1 and 2 are configured by a 28 dB × 4 span optical fiber and an optical amplification repeater, and the optical transmission path 3 is configured by a 28 dB × 6 span optical fiber and an optical amplification repeater. The transmission characteristics when the optical signal transmitted through each optical transmission line is received by ordinary digital coherent reception were 9.47 dB, 9.58 dB, and 7.55 dB in terms of Q value, respectively.

  The optical signal receiving device 70 includes a DP-QPSK receiver 71 that outputs coherently detected optical signals of wavelength λ1 transmitted through the optical transmission paths 1 to 3 and three data signals transmitted through the three paths. It comprises a MIMO processor 72 that performs 3 × 1 MIMO processing and outputs it as a data signal, and a signal identifier 73 that performs signal identification of the data signal.

  Here, a delay of 66 bits and 67 bits was given to the delay unit 62 and transmitted to each of the optical transmission lines 1 to 3. After transmission through each optical transmission line, the signal was received by the DP-QPSK receiver 71, and after waveform equalization was performed by digital signal processing, delay compensation and signal synthesis were performed by MIMO processing using the CMA algorithm. The transmission characteristics when signals from all optical transmission lines were combined was 12.72 dB in terms of Q value, confirming an improvement in transmission characteristics of 3.14 dB.

  Also, assuming that a failure has occurred in the transmission line, if one of the optical transmission lines is disconnected, the transmission characteristics when the optical transmission lines 1 and 2 are combined are 12.7 dB, and the optical transmission lines 1 and 3 are combined. The transmission characteristic was 11.51 dB, and the transmission characteristic when combining optical transmission lines 2 and 3 was 11.62 dB, both of which confirmed improved transmission characteristics compared to the single transmission. In this case, two optical transmission lines By determining the transmission distance based on the transmission characteristics obtained by combining and operating in three directions at normal times, transmission can be continued without interruption even if a failure occurs in any of the directions.

  FIG. 9 shows a constellation after digital signal processing of the DP-QPSK signal for each of the above transmission characteristics.

DESCRIPTION OF SYMBOLS 10 Optical signal transmitter 11 Client signal receiver 12 ODU-XC
13 Error correction encoder 14 Delay device 15 Optical transmitter 16 OTN framer 17 Optical XC device 20 Optical signal receiver 21 Client signal transmitter 22 ODU-XC
23 Error Correction Decoder 24 MIMO Processing Unit 25 Optical Receiver 26 OTN Framer 27 Optical XC Device 31 Controller 51, 52 Optical Transmission Line 151 Waveform Equalizer 152 D / A Converter 153 Coherent Optical Transmitter 251 Coherent Optical Receiver 252 A / D converter 253 Waveform equalizer

Claims (4)

Replicating data signal d by the number of wavelengths m × optical transmission line number n (m is an integer of 2 or more, n is an integer of 2 or more) sets a predetermined delay in each delay device, of the n for each wavelength of light An optical signal transmission device for converting into a signal;
an optical XC device 1 that wavelength-multiplexes m-wave optical signals to generate n wavelength-multiplexed optical signals and outputs them to n optical transmission lines;
An optical XC device 2 for inputting the n wavelength-multiplexed optical signals transmitted through the n optical transmission lines and demultiplexing them into m-wave optical signals;
An optical signal receiving device including a MIMO processing circuit that receives an optical signal of m × n waves demultiplexed by the optical XC device 2 and converts the optical signal into an electrical signal and performs (m × n) × m MIMO processing; And the transmission delay difference of the replicated data signal d in the n optical transmission lines is coarsely adjusted by the delay unit and finely adjusted by signal processing in the MIMO processing circuit to synthesize the data signal d. An optical transmission system characterized by having a configuration. s data signals d1 to ds are input (s is an integer of 2 or more), and each of the data signals d1 to ds is duplicated at a wavelength different from each other by the number of wavelengths m × the number of optical transmission lines n (m is 1). An optical signal transmission device that sets a predetermined delay by each delay device and converts the optical signal into n optical signals for each wavelength,
an optical XC apparatus 1 that wavelength-multiplexes m × s-wave optical signals to generate n wavelength-multiplexed optical signals and outputs them to n optical transmission lines;
An optical XC device 2 for inputting the n wavelength-multiplexed optical signals transmitted through the n optical transmission lines and demultiplexing them into m × s optical signals;
MIMO that receives an m × s optical signal demultiplexed by the optical XC device 2 and converts it into an electrical signal, and performs (m × n) × m MIMO processing for each of the same data signals d1 to ds An optical signal receiving device including a processing circuit, wherein a transmission delay difference in the n optical transmission lines of the data signal replicated for each of the data signals d1 to ds is coarsely adjusted by the delay unit, and the MIMO processing is performed An optical transmission system characterized in that the data signals d1 to ds are synthesized by fine adjustment by signal processing in a circuit. The optical transmission system according to claim 1 or 2,
In the optical signal receiving device, a delay amount to be set in the delay unit of the optical signal transmitting device according to the delay amount of the data signal converted and combined from the optical signal of each wavelength transmitted through the optical transmission path. An optical transmission system characterized by being configured to control. The optical transmission system according to claim 2,
Priorities are set for the data signals d1 to ds,
The optical signal transmitting apparatus and the optical signal receiving apparatus when a failure occurs in any of the n optical transmission paths and the wavelength multiplexed optical signal from the optical transmission path is not input to the optical signal receiving apparatus. Transmits the wavelength assigned to the low-priority data signal to the high-priority data signal and performs the (m × n) × m MIMO processing to transmit the high-priority data signal. An optical transmission system characterized in that it is configured to synthesize.

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