JP2013141048A - Optical communication system, optical communication method, fault detection device, fault detection method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical communication system that is able to prevent a decline in communication quality when an active transmission path is changed due to the occurrence of a fault.SOLUTION: An optical communication system 7000 transmits data by an optical signal from a transmitter to a receiver. The optical communication system has a plurality of transmission paths from the transmitter to the receiver, sets a first transmission path as an active transmission path, and transmits data from the transmitter to the receiver via the active transmission path (7001). The optical communication system obtains a variation quality value that is a temporal variation component due to polarization mode dispersion among values indicating quality of the optical signal having passed the first transmission path (7002). The optical communication system detects that a fault will occur on the first transmission path at a time point in the future on the basis of the variation quality value (7003). The optical communication system changes the active transmission path from the first transmission path to a second transmission path when the fault occurrence is detected.

Description

  The present invention relates to an optical communication system for transmitting data from a transmission device to a reception device using an optical signal.

  2. Description of the Related Art An optical communication system that transmits data using an optical signal from a transmission device to a reception device is known. As one of this type of optical communication system, an optical communication system described in Patent Document 1 has a plurality of transmission paths from a transmission device to a reception device.

  In this optical communication system, the first transmission path is set as an operation transmission path, and data is transmitted from the transmission apparatus to the reception apparatus via the set operation transmission path. Furthermore, the optical communication system detects whether or not a failure has occurred in the first transmission path based on the data received by the receiving device.

  Specifically, the optical communication system detects that a failure has occurred in the first transmission path when the number of error corrections in forward error correction (FEC) processing exceeds a predetermined threshold. . When the optical communication system detects that a failure has occurred in the first transmission path, it changes (switches) the operation transmission path from the first transmission path to the second transmission path.

  Accordingly, the optical communication system can accurately transmit data using the second transmission path even when a failure occurs in the first transmission path.

JP-A-2005-260820

  However, in the optical communication system, accurate data (that is, transmission from the transmission device) is performed during a period from when it is detected that a failure has occurred in the first transmission path to when switching of the operation transmission path is completed. The same data as the received data) cannot be received by the receiving device. That is, there is a problem that communication quality is deteriorated.

  In particular, the larger the amount of data transmitted per unit time, the greater the amount of data received by the receiving device during the period. Therefore, the above problem becomes more prominent as the amount of data transmitted per unit time increases.

  For this reason, the object of the present invention is to solve the above-mentioned problem that “the communication quality may be deteriorated when the operation transmission path is changed due to the occurrence of a failure”. It is to provide a communication system.

  In order to achieve such an object, an optical communication system according to an embodiment of the present invention includes a transmission device and a reception device, and transmits data from the transmission device to the reception device by an optical signal.

Furthermore, this optical communication system
Having a plurality of transmission paths from the transmitter to the receiver;
Data for setting a first transmission path as one of the plurality of transmission paths as an operation transmission path, and transmitting the data from the transmission apparatus to the reception apparatus via the set operation transmission path Transmission means;
Of the values representing the quality of the optical signal received by the receiver via the first transmission path, a first variation quality value that is a time variation component due to polarization mode dispersion is acquired. A variable quality value acquisition means;
Based on the acquired first variation quality value, failure occurrence detection means for detecting that a failure occurs in the first transmission path at a future time point;
With
When the data transmission means detects that a failure occurs in the first transmission path, the data transmission means changes the operation transmission path from the first transmission path to the first transmission path among the plurality of transmission paths. The second transmission path is different from the first transmission path.

An optical communication method according to another aspect of the present invention is
In addition to including a transmission device and a reception device, it is applied to an optical communication system that transmits data by optical signals from the transmission device to the reception device,
A first transmission path, which is one of a plurality of transmission paths from the transmission apparatus to the reception apparatus, is set as an operation transmission path, and the reception from the transmission apparatus is performed via the set operation transmission path. Transmit the above data to the device,
Of the values representing the quality of the optical signal received by the receiver via the first transmission path, a first variation quality value that is a time variation component due to polarization mode dispersion is acquired. ,
Based on the acquired first variation quality value, detecting that a failure occurs in the first transmission path at a future time point,
When it is detected that a failure occurs in the first transmission path, the operation transmission path is different from the first transmission path from the first transmission path to the first transmission path. This is a method of changing to the second transmission path.

In addition, the failure detection apparatus according to another aspect of the present invention is
A fluctuation quality value acquisition unit that acquires a fluctuation quality value that is a time fluctuation component caused by polarization mode dispersion among values representing the quality of the optical signal when the optical signal is input;
Based on the obtained variation quality value, failure occurrence detection means for detecting that a failure occurs in a transmission path through which the optical signal is transmitted at a future time point;
Is provided.

In addition, a failure detection method according to another aspect of the present invention includes:
An optical signal is input, and a fluctuation quality value that is a time fluctuation component due to polarization mode dispersion is acquired from values representing the quality of the optical signal,
This is a method for detecting that a failure occurs in a transmission path through which the optical signal is transmitted at a future time point based on the obtained fluctuation quality value.

Moreover, the program which is the other form of this invention is:
In the failure detection device to which the optical signal is input,
Of the values representing the quality of the optical signal, a fluctuation quality value acquisition means for acquiring a fluctuation quality value that is a time fluctuation component caused by polarization mode dispersion;
Based on the obtained variation quality value, failure occurrence detection means for detecting that a failure occurs in a transmission path through which the optical signal is transmitted at a future time point;
It is a program for realizing.

  By configuring as described above, the present invention can prevent the communication quality from deteriorating when the operation transmission path is changed due to the occurrence of a failure.

1 is a diagram illustrating a schematic configuration of an optical communication system according to a first embodiment of the present invention. It is the graph which showed an example of the time change of a fluctuation quality value. It is the graph which showed the time change of the value which smoothed the fluctuation | variation quality value shown in FIG. FIG. 2 is a block diagram showing the configuration of each node device shown in FIG. 1 in more detail. It is a figure showing schematic structure of the optical communication system which concerns on 2nd Embodiment of this invention. It is the graph showing an example of the relationship between SOP vector locus | trajectory length and a fluctuation | variation quality value. It is a block diagram showing the function of the optical communication system which concerns on 3rd Embodiment of this invention.

  Hereinafter, embodiments of an optical communication system, an optical communication method, a failure detection device, a failure detection method, and a program according to the present invention will be described with reference to FIGS.

<Outline of Embodiment>
The optical communication system according to each embodiment of the present invention has a plurality of transmission paths for transmitting data using optical signals. The plurality of transmission paths include a first transmission path and a second transmission path from the transmission apparatus to the reception apparatus. The optical communication system sets the first transmission path or the second transmission path as an operation transmission path, and transmits data from the transmission apparatus to the reception apparatus via the operation transmission path.

  The optical communication system acquires a fluctuation quality value that is a time fluctuation component due to polarization mode dispersion among values representing the quality of an optical signal that has passed through a first transmission path set as an operation transmission path. The optical communication system detects that a failure occurs in the first transmission path at a future time based on the obtained fluctuation quality value (that is, predicts the occurrence of the failure).

  When it is detected that a failure occurs in the first transmission path, the optical communication system changes the operation transmission path from the first transmission path to the second transmission path before the actual failure occurs. . Thereby, it is possible to prevent the receiving device from receiving erroneous data (that is, data different from the data transmitted from the transmitting device).

  By the way, as the amount of data transmitted per unit time increases (that is, the capacity of the communication service increases), the receiving apparatus becomes more active during the period from when a failure actually occurs until the change of the operation transmission path is completed. The amount of data to be received increases. Therefore, a further effect is exhibited by this embodiment.

  In other words, since the above period (that is, the time for which the communication service is disconnected (shut down)) is shortened, the retransmission control of the data accompanying the loss of the transmitted data is suppressed, so the communication service is made faster. can do. In addition, when the above period does not exist (the length of the period is zero), the optical communication system is set as if no failure has occurred even though a failure has actually occurred. Can be operated. That is, the reliability of the optical communication system can be improved.

  In addition, when data is transmitted by an optical signal, factors causing fluctuations in the quality of the optical signal include physical phenomena such as chromatic dispersion, polarization dispersion, optical S / N (Signal-to-Noise), and nonlinear distortion. Conceivable. Of these, a particularly important factor is polarization mode dispersion (PMD).

  This is because the variation in quality due to PMD is irregular and a high-speed phenomenon, and it is difficult to suppress the variation in quality by performing compensation or the like. On the other hand, other factors are relatively regular and low-speed phenomena, so that quality fluctuations can be suppressed by performing compensation or the like. Therefore, the variation in the quality of the optical signal is predominantly due to PMD. That is, it is particularly important to monitor quality fluctuations due to PMD.

  By the way, when a failure occurs due to PMD, the failure often occurs because the quality of the optical signal rapidly decreases in a very short time (that is, instantaneously). In such a case, out of the values representing the quality of the optical signal, monitoring only the time-varying component due to PMD causes the occurrence of a failure rather than monitoring the entire value representing the quality of the optical signal. The inventor has found that it is easy to detect in advance.

  Therefore, the optical communication system acquires a fluctuation quality value that is a time fluctuation component due to polarization mode dispersion among values representing the quality of the optical signal, and based on the fluctuation quality value, at a future time point, Detect that a failure has occurred.

  By the way, in order to monitor the quality of a signal, the number of error corrections in a bit error rate (BER) or forward error correction (FEC) processing is often used.

  However, when the number of error corrections in BER or FEC processing is used, it is not possible to extract only the fluctuation quality value caused by PMD. Therefore, the optical communication system detects the SOP (State of Polarization) vector trajectory length or the degree of polarization having a strong correlation with the fluctuation quality value caused by PMD, and acquires the fluctuation quality value based on the detected value. . Here, the SOP vector trajectory length is the length of the trajectory drawn by the Stokes vector on the Poincare sphere within the wavelength band of the optical signal. The degree of polarization is also called DOP (Degree of Polarization). Thereby, the occurrence of a failure can be predicted with high accuracy.

  Further, when a value representing the quality of an optical signal is acquired based on the number of error corrections or code error rate in the FEC processing, an optical signal representing data (that is, a modulated optical signal (modulated light)). Is required. On the other hand, when a value representing the quality of an optical signal is acquired based on the SOP vector locus length or the degree of polarization, modulated light, continuous wave (CW), or amplified spontaneous emission (ASE) is obtained. Amplified Spontaneous Emission) light can be used.

  Therefore, for example, when acquiring a value representing the quality of an optical signal in a transmission path (standby transmission path) that is not set as an operation transmission path, modulated light is used by using CW light or ASE light. A value representing the quality of the optical signal can be obtained more easily than in the case. That is, a value representing the quality of the optical signal can be acquired by using a simple light source. As a result, it is possible to reduce the facility / operation cost for predicting the occurrence of a failure in the backup transmission path.

  Further, in an optical communication system, because it is difficult to handle a complicated control protocol, and because a time required for a transmission device (optical transmission device) to operate stably is relatively long, In many cases, a hot standby method is used in which power for transmitting data via a backup transmission path is supplied in advance. By the way, the hot standby method has a problem that the operation cost and the amount of power consumption are large compared to the cold standby method in which the supply of power for transmitting data via the backup transmission path is stopped.

  By the way, the optical communication system according to the present invention predicts the occurrence of a failure, and changes the operation transmission path before the failure actually occurs. Therefore, it is possible to secure a relatively long time from the time when it is detected that a failure occurs at a future time to the time when the failure actually occurs. Therefore, even if power for transmitting data via the backup transmission path is not supplied in advance, preparation for transmission of data via the backup transmission path is completed by the time when the failure actually occurs. be able to.

  Therefore, the optical communication system according to one of the embodiments of the present invention uses the power for transmitting data via the backup transmission path until it is detected that a failure occurs in the operation transmission path. Stop supplying. Thereby, the operation cost or the power consumption can be reduced.

  As described above, according to the optical communication system according to the embodiment of the present invention, high reliability of the optical communication system, high speed of the communication service, reduction in equipment / operation cost of the optical communication system, and low power consumption are achieved. It can be realized.

<First Embodiment>
(Constitution)
As shown in FIG. 1, the optical communication system 1000 according to the first embodiment includes a plurality (three in this example) of node devices (communication devices) 1001, 1002, and 1003. In this example, the node device 1001 is also called a transmission device. The node device 1002 is also called a receiving device. In addition, the node device 1001 and the node device 1002 constitute a data transmission unit.

  The node device 1001 is connected to the node device 1002 via the optical fiber 1004. Further, the node device 1001 is connected to the node device 1003 via the optical fiber 1005. In addition, the node device 1003 is connected to the node device 1002 via the optical fiber 1006.

  The transmission path of the optical signal that reaches the node apparatus 1002 from the node apparatus 1001 via the optical fiber 1004 is also called a first transmission path. The transmission path of the optical signal that reaches the node apparatus 1002 from the node apparatus 1001 via the optical fiber 1005, the node apparatus 1003, and the optical fiber 1006 is also called a second transmission path. As described above, the optical communication system 1000 has a plurality of transmission paths including the first transmission path and the second transmission path.

  The node device 1001 is configured to be able to output an optical signal representing data to each of the optical fiber 1004 and the optical fiber 1005. The node device 1001 receives the output control signal from the node device 1002, and outputs an optical signal to one of the optical fiber 1004 and the optical fiber 1005 in accordance with the output control signal. The output control signal represents that the first transmission path or the second transmission path is set as the operation transmission path.

The node device 1003 receives the optical signal from the node device 1001 via the optical fiber 1005, and outputs (transfers) the received optical signal to the optical fiber 1006.
The node device 1002 receives the optical signal transmitted from the node device 1001 and that has passed through the first transmission path or the second transmission path.

The optical communication system 1000 includes a plurality (three in this example) of optical amplifiers (optical amplifiers) 1007, 1008, 1009 and a polarizer 1015.
The optical amplifier 1007 is disposed on the optical fiber 1004. The optical amplifier 1007 amplifies the optical signal transmitted by the node device 1001.
The optical amplifier 1008 is disposed in the optical fiber 1005. The optical amplifier 1008 amplifies the optical signal transmitted by the node device 1001.

The optical amplifier 1009 is disposed on the optical fiber 1006. The optical amplifier 1009 amplifies the optical signal transmitted by the node device 1003.
The polarizer 1015 sets the polarization state of the optical signal amplified by the optical amplifier 1008 to a preset state and outputs it to the optical fiber 1005.

  Note that the optical signal transmitted by the node device 1001 is received by the node device 1002 after the quality varies due to various factors while being transmitted via the transmission path.

  Further, the optical communication system 1000 includes a plurality (two in this example) of optical demultiplexers 1010 and 1011, a plurality (two in this example) of optical signal quality monitors (fault detection devices) 1012 and 1013, and . The optical signal quality monitor 1013 constitutes a fluctuation quality value acquisition unit and a failure occurrence detection unit.

  The optical demultiplexer 1010 is disposed at the end of the optical fiber 1006 on the node device 1002 side. The optical demultiplexer 1010 branches the optical signal transmitted by the optical fiber 1006, and the optical signal quality of the branched optical signal (that is, the optical signal received by the receiving device 1002 via the second transmission path). Output to the monitor 1012.

  Similarly, the optical demultiplexer 1011 is disposed at the end of the optical fiber 1004 on the node device 1002 side. The optical demultiplexer 1011 branches the optical signal transmitted by the optical fiber 1004, and the optical signal quality of the branched optical signal (that is, the optical signal received by the receiving device 1002 via the first transmission path). Output to the monitor 1013.

  The optical signal quality monitor 1012 is a fluctuation quality value that is a time fluctuation component due to polarization mode dispersion among values representing the quality of an input optical signal (that is, an optical signal that has passed through the second transmission path). (Second variation quality value) is acquired. In this example, the optical signal quality monitor 1012 measures (detects) the SOP vector trajectory length, and acquires a variation quality value based on the measured value. Note that the optical signal quality monitor 1012 may be configured to detect the degree of polarization and acquire the fluctuation quality value based on the detected value.

  Specifically, the optical signal quality monitor 1012 stores information representing the relationship between the SOP vector trajectory length and the fluctuation quality value based on the measurement values obtained through experiments performed in advance. Then, the optical signal quality monitor 1012 acquires a variation quality value based on the measured SOP vector locus length and the stored information.

  The optical signal quality monitor 1012 represents the quality of the optical signal based on the SOP vector trajectory length or the degree of polarization (DOP) using, for example, a method disclosed in Japanese Unexamined Patent Application Publication No. 2009-260875. Of the values, a time variation component due to PMD may be acquired.

  The optical signal quality monitor 1012 outputs a failure occurrence warning signal to the node device 1002 when the obtained fluctuation quality value satisfies a predetermined detection condition. The failure occurrence warning signal indicates that a failure has been detected at a future time.

  The optical signal quality monitor 1013 has the same configuration as the optical signal quality monitor 1012. The optical signal quality monitor 1013 is a fluctuation quality value that is a time fluctuation component due to polarization mode dispersion among values representing the quality of an input optical signal (that is, an optical signal that has passed through the first transmission path). (First variation quality value) is acquired. The optical signal quality monitor 1013 outputs a failure occurrence warning signal to the node device 1002 when the obtained variation quality value satisfies the detection condition.

  When the node device 1002 receives the failure occurrence warning signal, the node device 1002 changes the transmission path set as the operation transmission path.

  That is, when the node apparatus 1002 receives a failure occurrence warning signal from the optical signal quality monitor 1013 when the first transmission path is set as the operation transmission path, the node apparatus 1002 changes the operation transmission path from the first transmission path to the first transmission path. Change to 2 transmission path. Specifically, the node device 1002 transmits to the node device 1001 an output control signal indicating that the second transmission path is set as the active transmission path.

  In addition, when the second transmission path is set as the operational transmission path, the node device 1002 changes the operational transmission path from the second transmission path to the second transmission path when the failure warning signal is received from the optical signal quality monitor 1012. Change to 1 transmission path. Specifically, the node device 1002 transmits an output control signal indicating that the first transmission path is set as the active transmission path to the node device 1001.

Next, the optical signal quality monitors 1012 and 1013 will be described in more detail.
FIG. 2 is a graph showing an example of a change over time of a fluctuation quality value, which is a time fluctuation component due to polarization mode dispersion, among values representing the quality of an optical signal. In this example, it is assumed that a failure actually occurs when the fluctuation quality value falls below the quality degradation threshold Qth at time t2. Note that the actual occurrence of a failure corresponds to, for example, that the number of error corrections in the FEC process becomes larger than a preset threshold value. The quality degradation threshold value Qth is a threshold value at which a failure actually occurs among the fluctuation quality values.

  By the way, as described above, PMD is dominant in the factor of fluctuation of the quality of the optical signal. PMD changes the quality of an optical signal irregularly and at high speed. Therefore, as shown in FIG. 2, in a normal time (that is, a time point before time t1), the fluctuation quality value has a value sufficiently larger than the quality deterioration threshold value Qth. During a short time (during the period between time t1 and time t2), it rapidly decreases and falls below the quality degradation threshold Qth.

  At this time, the fluctuation quality value decreases below the quality degradation threshold Qth as a result of decreasing while vibrating. Furthermore, the fluctuation quality value falls below the quality degradation threshold Qth as a result of vibration while increasing the amplitude.

  Therefore, each of the optical signal quality monitors 1012 and 1013 has a ratio of the sum of the times when the fluctuation quality value becomes smaller than the preset quality threshold within the preset judgment period to the judgment period. When the ratio threshold value is exceeded or more and the variation rate with time is a negative value, it is detected that a failure will occur at a future time in the transmission path to be detected.

  Thereby, it can be detected that a failure has occurred at a time before the time when the fluctuation quality value actually falls below the quality deterioration threshold Qth.

  Specifically, each of the optical signal quality monitors 1012 and 1013 has a time point when the obtained variation quality value falls below the PMD-induced quality variation threshold Qpmd (quality threshold) (becomes smaller than the PMD-induced quality variation threshold Qpmd). The time measurement by the timer is started. Here, the PMD-induced quality fluctuation threshold Qpmd is set to a value larger than the quality deterioration threshold Qth.

  Each of the optical signal quality monitors 1012 and 1013 obtains the fluctuations obtained during the period (determination period) from when the time measured by the timer starts until the time measured by the timer exceeds a preset time threshold T. The sum of the time when the quality value becomes smaller than the PMD-induced quality variation threshold Qpmd (that is, less than the PMD-induced quality variation threshold Qpmd) is measured.

  In the example shown in FIG. 2, this sum is T1 + T2 + T3 + T4 + T5 + T6. Furthermore, each of the optical signal quality monitors 1012 and 1013 calculates a value R = (T1 + T2 + T3 + T4 + T5 + T6) / T obtained by dividing the measured sum by a time threshold T (that is, the length of the determination period). That is, the value R is the ratio of the sum to the determination period.

  On the other hand, each of the optical signal quality monitors 1012 and 1013 calculates a time change rate (that is, time differential value) Q ′ of the fluctuation quality value. By the way, the obtained variation quality value includes a measurement error and / or a minute variation component caused by noise light. For this reason, there is a possibility that the time change rate of the fluctuation quality value cannot be calculated with high accuracy.

  Therefore, each of the optical signal quality monitors 1012 and 1013 acquires the time change rate of the value obtained by smoothing the obtained fluctuation quality value as the time change rate of the fluctuation quality value. Here, FIG. 3 is a graph showing a time change of a value obtained by smoothing the variation quality value shown in FIG.

  In this example, each of the optical signal quality monitors 1012 and 1013 smoothes the obtained variation quality value by using a low-pass filter. Note that each of the optical signal quality monitors 1012 and 1013 may be configured to use a Savitzky-Golay filter.

  Thereby, the influence which the measurement error and / or the minute fluctuation component resulting from the noise light exert on the time change rate of the fluctuation quality value can be reduced. As a result, the time change rate of the fluctuation quality value can be acquired with high accuracy.

  In each of the optical signal quality monitors 1012 and 1013, the calculated value R is equal to or greater than a preset ratio threshold value Rth, and the time variation rate Q ′ of the calculated variation quality value is a negative value. Then, it detects that a failure occurs at a future point in the transmission path to be detected. That is, the condition that the value R is equal to or greater than the ratio threshold value Rth and the temporal change rate Q ′ of the fluctuation quality value is a negative value is also called a detection condition. Further, the transmission path to be detected is the second transmission path for the optical signal quality monitor 1012 and the first transmission path for the optical signal quality monitor 1013.

  Each optical signal quality monitor 1012 and 1013 outputs a failure occurrence warning signal to the node device 1002 when detecting that a failure will occur at a future time point on the transmission path to be detected.

  Here, of the values representing the quality of the optical signal, the effect of predicting the occurrence of a failure using the variation quality value that is a time variation component caused by polarization mode dispersion is expressed as BER or FEC processing. This will be described in comparison with the case where the number of error corrections in FIG.

  In the case where BER is used as a value representing the quality of the optical signal, a value corresponding to the PMD-induced quality fluctuation threshold Qpmd shown in FIG. 2 will be described as a quality fluctuation threshold Qber.

  The difference between the PMD-induced quality variation threshold Qpmd and the quality variation threshold Qber is a value based on only the time-variable component of the values represented by the PMD-derived quality variation threshold Qpmd, whereas the quality variation threshold Qber. The threshold value Qber is a value based not only on a time-varying component but also on a fixed component that usually hardly changes.

  That is, if a value representing the quality of the optical signal is Q (t), Q (t) is the sum of ΔQ (t) that is a time-varying component and a component Q0 that hardly changes during normal times. Can think. That is, Q (t) = ΔQ (t) + Q0.

  By the way, when PMD is dominant as a factor that varies the quality of an optical signal, the PMD-induced quality variation threshold Qpmd is substantially a threshold for ΔQ (t), while the quality variation threshold Qber is substantially The threshold for Q (t).

  Further, from the PMD characteristics in the transmission path, the fluctuation range of ΔQ (t) can be estimated relatively accurately. Therefore, it is relatively easy to appropriately set the value of the PMD-induced quality fluctuation threshold Qpmd.

  However, since Q0 changes depending on various characteristics such as a transmission path and a node device, it is difficult to accurately estimate the fluctuation range of Q (t). For this reason, it is difficult to appropriately set the value of the quality fluctuation threshold Qber.

  Therefore, it is effective to use an SOP vector trajectory length or a degree of polarization (DOP) that can extract only a time-varying component caused by PMD among values representing the quality of an optical signal.

  In addition, each optical signal quality monitor 1012 and 1013 has a state in which the time variation rate of the obtained variation quality value is a negative value and continues for a preset threshold time or more, at a future time point, You may be comprised so that it may detect that a failure generate | occur | produces in the transmission path | route used as a detection target. This also makes it possible to detect that a failure has occurred at a time before the time when the fluctuation quality value actually falls below the quality deterioration threshold Qth.

(Operation)
Next, the operation of the optical communication system 1000 will be described.
First, the optical communication system 1000 sets the first transmission path as an operation transmission path. Accordingly, the node device 1001 outputs an optical signal representing data to the optical fiber 1004. That is, the node device 1001 transmits an optical signal to the node device 1002 via the first transmission path. Thereby, the node device 1002 receives the optical signal, and restores the data transmitted by the node device 1001 based on the received optical signal.
In this way, data is transmitted from the node device 1001 to the node device 1002.

  The optical signal quality monitor 1013 receives the optical signal output from the optical demultiplexer 1011. Then, the optical signal quality monitor 1013 obtains a first fluctuation quality value that is a time fluctuation component due to polarization mode dispersion among values representing the quality of the input optical signal.

  The optical signal quality monitor 1013 determines whether or not the acquired first variation quality value satisfies the detection condition. Assume that the optical signal quality monitor 1013 determines that the acquired first fluctuation quality value satisfies the detection condition at time t3 in FIG.

  In this case, the optical signal quality monitor 1013 transmits a failure occurrence warning signal to the node device 1002. When receiving the failure occurrence warning signal, the node device 1002 transmits an output control signal to the node device 1001.

Thereby, the node device 1001 receives the output control signal. Then, the node device 1001 changes (switches) the output destination of the optical signal from the optical fiber 1004 to the optical fiber 1005. That is, the node device 1001 changes the operation transmission path from the first transmission path to the second transmission path.
Thereby, thereafter, the optical signal transmitted by the node device 1001 reaches the node device 1002 via the second transmission path.

  As described above, according to the optical communication system 1000 according to the first embodiment of the present invention, the optical communication system 1000 actually fails in the first transmission path (for example, in error correction processing). The operational transmission path can be changed at a time before the time at which the number of error corrections becomes greater than a predetermined threshold. As a result, it is possible to avoid the node device 1002 (reception device) receiving erroneous data (that is, data different from the data transmitted from the node device 1001 (transmission device)).

  That is, according to the optical communication system 1000, it is possible to prevent the communication quality from deteriorating when the operation transmission path is changed due to the occurrence of a failure.

<First Modification of First Embodiment>
Next, a first modification of the first embodiment will be described. The optical communication system according to the first modification is different from the optical communication system according to the first embodiment in that the supply of power related to the backup transmission path is stopped until the occurrence of an abnormality is detected. ing. Accordingly, the following description will focus on such differences.

FIG. 4 is a block diagram showing the configuration of each of the node devices 1001, 1002, and 1003 in FIG. 1 in more detail.
The node device 1001 includes a plurality (two in this example) of optical transmitters 4001 and 4002. The optical transmitter 4001 outputs (sends) an optical signal to the optical fiber 1004. The optical transmitter 4002 outputs (sends) an optical signal to the optical fiber 1005.

  The node device 1002 includes a plurality (two in this example) of optical receivers 4003 and 4004. The optical receiver 4003 receives (inputs) an optical signal via the optical fiber 1004. The optical receiver 4004 receives (inputs) an optical signal via the optical fiber 1006.

  The node device 1003 includes an optical switch 4005. The optical switch 4005 outputs the input optical signal without terminating it. The optical switch 4005 is configured to change (switch) the output destination of the input optical signal. In FIG. 4, only the path connecting the optical fiber 1005 and the optical fiber 1006 is shown for the sake of simplicity.

  Incidentally, in general, in an optical communication system, a 1 + 1 protection method, which is a hot standby method, is used as a transmission path switching method when a failure occurs. This is because in an optical communication system, it is difficult to perform processing based on a complicated control protocol, and a relatively long time is required until the node device operates stably.

  By the way, when the 1 + 1 protection method is used, it is necessary to always prepare a standby transmission path equivalent to the operation transmission path. Therefore, even during normal times, power is supplied to transmit data via the backup transmission path, and an optical signal equivalent to the optical signal transmitted via the operation transmission path is sent to the backup transmission path. Must also be transmitted through.

  As a result, the equipment cost for providing a dedicated spare transmission path for one operational transmission path and the operational cost for always operating the spare transmission path in addition to the operational transmission path are required. By the way, if it is possible to secure a relatively long grace time until a failure actually occurs by detecting the occurrence of the failure in advance, it is not necessary to always operate the backup transmission path.

  This is because the occurrence of a failure is detected and the preparation for changing the operation transmission path (for example, the supply of power related to the backup transmission path) is started at a time before the actual occurrence of the failure. Because it can.

  Therefore, in the optical communication system 1000 according to the first modified example, the first transmission path is set as the operation transmission path and the occurrence of a failure in the first transmission path is detected until the first transmission path is detected. The supply of power for transmitting data via the transmission path 2 is stopped. Specifically, the optical communication system 1000 stops (cuts off) power supply to the optical transmitter 4002, the optical amplifier 1008, the optical switch 4005, the optical amplifier 1009, and the optical receiver 4004.

  Furthermore, when the node apparatus 1002 receives the failure occurrence warning signal from the optical signal quality monitor 1013, the optical communication system 1000 starts supplying power for transmitting data via the second transmission path. Specifically, the optical communication system 1000 starts supplying power to the optical transmitter 4002, the optical amplifier 1008, the optical switch 4005, the optical amplifier 1009, and the optical receiver 4004.

  The node device 1002 transmits an output control signal to the node device 1001 after a preset standby time has elapsed from the time when the failure occurrence warning signal is received from the optical signal quality monitor 1013.

  According to the optical communication system 1000 according to the first modification, power for transmitting data is supplied via the second transmission path even when the first transmission path is set as the operation transmission path. Compared with the case where it is doing, the electric energy which the optical communication system 1000 consumes can be reduced.

<Second Modification of First Embodiment>
Next, a second modification of the first embodiment will be described. The optical communication system according to the second modification is different from the optical communication system according to the first embodiment in that a failure is detected in the backup transmission path based on noise light output from the optical amplifier. It is different. Accordingly, the following description will focus on such differences.

FIG. 4 is a block diagram showing the configuration of each of the node devices 1001, 1002, and 1003 in FIG. 1 in more detail.
The node device 1001 includes a plurality (two in this example) of optical transmitters 4001 and 4002. The optical transmitter 4001 outputs (sends) an optical signal to the optical fiber 1004. The optical transmitter 4002 outputs (sends) an optical signal to the optical fiber 1005.

  The node device 1002 includes a plurality (two in this example) of optical receivers 4003 and 4004. The optical receiver 4003 receives (inputs) an optical signal via the optical fiber 1004. The optical receiver 4004 receives (inputs) an optical signal via the optical fiber 1006.

  The node device 1003 includes an optical switch 4005. The optical switch 4005 outputs the input optical signal without terminating it. The optical switch 4005 is configured to change (switch) the output destination of the input optical signal. In FIG. 4, only the path connecting the optical fiber 1005 and the optical fiber 1006 is shown for the sake of simplicity.

  In the optical communication system 1000 according to the second modification, the first transmission path is set as the operation transmission path, and the second transmission period is detected until a failure is detected in the first transmission path. The supply of power for transmitting data via the transmission path to the node device 1001 (transmission device) is stopped. Specifically, the optical communication system 1000 stops (cuts off) the supply of power to the optical transmitter 4002.

  The optical signal quality monitor 1012 receives the first optical signal received by the optical receiver 4004 included in the node device 1002 (reception device) and outputs noise light output from the optical amplifiers 1008 and 1009 arranged in the second transmission path. Get a variable quality value of 2.

  According to this, even when the first transmission path is set as the operation transmission path, the power for transmitting data via the second transmission path is supplied to the transmission device (that is, the optical transmission path). Compared with the case where power is supplied to the transmitter 4002), the amount of power consumed by the optical communication system 1000 can be reduced.

  The node device 1002 receives the failure occurrence warning signal from the optical signal quality monitor 1013 (that is, it is detected that a failure has occurred in the first transmission path), and the failure has occurred from the optical signal quality monitor 1012. When the warning signal has not been received (that is, it has not been detected that a failure has occurred in the second transmission path), an output control signal is transmitted to the node device 1001.

  According to the optical communication system 1000 according to the second modification, it is possible to avoid the occurrence of a failure in the second transmission path immediately after changing the operation transmission path. As a result, the optical communication system 1000 can reliably transmit data from the node device 1001 (transmitting device) to the node device 1002 (receiving device). That is, the reliability of the optical communication system 1000 can be improved.

Second Embodiment
Next, an optical communication system according to a second embodiment of the present invention will be described. The optical communication system according to the second embodiment is different from the optical communication system according to the first embodiment in that wavelength division multiplexing communication is performed in which a plurality of optical signals having different wavelengths are superimposed on an optical fiber. . Accordingly, the following description will focus on such differences.

  As shown in FIG. 5, the optical communication system 5000 according to the second embodiment includes node devices 5001, 5002, and 5003 corresponding to the node devices 1001, 1002, and 1003 in FIG. 1, and the optical fiber 1004 in FIG. 1, optical fibers 5004, 5005, 5006 corresponding to the optical amplifiers 1005, 1006, optical amplifiers 5007, 5008, 5009 respectively corresponding to the optical amplifiers 1007, 1008, 1009 in FIG. 1, and optical demultiplexers 1010, 1011 in FIG. Respective optical demultiplexers 5010 and 5011, optical signal quality monitors 5012 and 5013 corresponding to the optical signal quality monitors 1012 and 1013 in FIG. 1, respectively, and a polarizer 5015 corresponding to the polarizer 1015 in FIG. Prepare.

  The optical communication system 5000 further includes wavelength multiplexers 5017 and 5018 and wavelength separators 5019 and 5020.

The node device 5001 includes a plurality (eight in this example) of optical transmitters 5031 to 5038.
Each optical transmitter 5031 to 5034 outputs an optical signal to the wavelength multiplexer 5018. Each of the optical transmitters 5031 to 5034 outputs (transmits) optical signals having different wavelengths (λ1, λ2, λ3, or λ4 in this example). The wavelength multiplexer 5018 superimposes the input optical signal and outputs it to the optical amplifier 5008.

  Similarly, each of the optical transmitters 5035 to 5038 outputs an optical signal to the wavelength multiplexer 5017. Each of the optical transmitters 5035 to 5038 outputs (transmits) optical signals having different wavelengths (λ1, λ2, λ3, or λ4 in this example). The wavelength multiplexer 5017 superimposes the input optical signal and outputs it to the optical amplifier 5007.

The node device 5002 includes a plurality (eight in this example) of optical receivers 5021 to 5028.
The wavelength separator 5019 receives the optical signal transmitted from the first transmission path (output from the optical amplifier 5007), separates the input optical signal into optical signals for each wavelength, and separates them. Each optical signal is output to each optical receiver 5025-5028. Each of the optical receivers 5025 to 5028 inputs (receives) optical signals having different wavelengths (λ1, λ2, λ3, or λ4 in this example).

  The wavelength separator 5020 receives an optical signal (output from the optical amplifier 5009) transmitted via the second transmission path, separates the input optical signal into optical signals for each wavelength, and separates them. Each optical signal is output to each optical receiver 5021-5024. Each of the optical receivers 5021 to 5024 inputs (receives) optical signals having different wavelengths (in this example, λ1, λ2, λ3, or λ4).

  With such a configuration, the optical communication system 5000 transmits data from the node device 5001 to the node device 5002 by wavelength division multiplex communication (WDM; Wavelength Division Multiplex).

  Similar to the optical signal quality monitor 1013, the optical signal quality monitor 5013 is a fluctuation quality value that is a time fluctuation component due to polarization mode dispersion among values representing the quality of the optical signal that has passed through the first transmission path. (First variation quality value) is acquired. In this example, the optical signal quality monitor 5013 measures (detects) the SOP vector trajectory length, and acquires a fluctuation quality value based on the measured value.

  FIG. 6 is a graph showing an example of the relationship between the SOP vector trajectory length and the fluctuation quality value. By the way, it has been experimentally found that this relationship hardly changes due to factors other than PMD. Therefore, the optical signal quality monitor 5013 obtains the fluctuation quality value based on the relationship between the SOP vector trajectory length and the fluctuation quality value, and the measured SOP vector trajectory length, based on the measurement values obtained in advance through experiments. To do. Thereby, the fluctuation quality value can be acquired with high accuracy.

  Incidentally, the optical signal quality monitor 5013 can measure the SOP vector locus length without separating the input optical signal for each wavelength. Therefore, the optical signal quality monitor 5013 can acquire a variation quality value for each wavelength based on the SOP vector locus length measured for each wavelength. In other words, the optical signal quality monitor 5013 can acquire the fluctuation quality value as in the case where the input optical signal is an optical signal having only a single wavelength.

  As described above, when the variation quality value is acquired based on the SOP vector locus length, it is not necessary to provide a different device for each wavelength of the optical signal. Therefore, even when the optical communication system 5000 is configured to perform wavelength division multiplexing communication, it is possible to avoid an excessive cost for manufacturing the optical communication system 5000.

  As described above, according to the optical communication system 5000 according to the second embodiment of the present invention, operations and effects similar to those of the optical communication system 1000 according to the first embodiment can be achieved.

<Third Embodiment>
Next, an optical communication system according to a third embodiment of the present invention will be described with reference to FIG.
An optical communication system 7000 according to the second embodiment is a system that includes a transmission device and a reception device, and transmits data from the transmission device to the reception device using an optical signal.

Further, the optical communication system 7000 includes:
Having a plurality of transmission paths from the transmitter to the receiver;
Data for setting a first transmission path as one of the plurality of transmission paths as an operation transmission path, and transmitting the data from the transmission apparatus to the reception apparatus via the set operation transmission path A transmission unit (data transmission means) 7001;
Of the values representing the quality of the optical signal received by the receiver via the first transmission path, a first variation quality value that is a time variation component due to polarization mode dispersion is acquired. A fluctuation quality value acquisition unit (fluctuation quality value acquisition means) 7002;
A failure occurrence detection unit (failure occurrence detection means) 7003 for detecting that a failure occurs in the first transmission path at a future time based on the acquired first variation quality value;
With
When it is detected that a failure occurs in the first transmission path, the data transmission unit 7001 moves the operation transmission path from the first transmission path to the corresponding one of the plurality of transmission paths. The second transmission path is different from the first transmission path.

  According to this, the optical communication system 7000 has a time point before a time point when a failure actually occurs in the first transmission path (for example, the number of error corrections in the error correction process becomes larger than a predetermined threshold). Thus, the operation transmission path can be changed. As a result, it is possible to prevent the receiving device from receiving erroneous data (that is, data different from the data transmitted from the transmitting device).

  That is, according to the optical communication system 7000, it is possible to prevent the communication quality from deteriorating when the operation transmission path is changed due to the occurrence of a failure.

  Although the present invention has been described with reference to the above embodiment, the present invention is not limited to the above-described embodiment. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

  In each of the above embodiments, each function of the optical communication system is realized by hardware such as a circuit. By the way, in the optical communication system, each device constituting the optical communication system includes a processing device and a storage device that stores a program (software), and the processing device executes the program so that each function is achieved. It may be configured to be realized. In this case, the program may be stored in a computer-readable recording medium. For example, the recording medium is a portable medium such as a flexible disk, an optical disk, a magneto-optical disk, and a semiconductor memory.

  In addition, as another modified example of the above-described embodiment, any combination of the above-described embodiments and modified examples may be employed.

<Appendix>
A part or all of the above embodiment can be described as the following supplementary notes, but is not limited thereto.

(Appendix 1)
An optical communication system that includes a transmission device and a reception device, and transmits data from the transmission device to the reception device by an optical signal,
A plurality of transmission paths from the transmitting device to the receiving device;
Data that sets a first transmission path, which is one of the plurality of transmission paths, as an operating transmission path, and transmits the data from the transmitting apparatus to the receiving apparatus via the set operating transmission path Transmission means;
Of the values representing the quality of the optical signal received by the receiving device via the first transmission path, a first variation quality value that is a time variation component due to polarization mode dispersion is acquired. A variable quality value acquisition means;
A failure occurrence detection means for detecting that a failure occurs in the first transmission path at a future time point based on the acquired first variation quality value;
With
When it is detected that a failure occurs in the first transmission path, the data transmission means changes the operation transmission path from the first transmission path to the first transmission path among the plurality of transmission paths. An optical communication system configured to change to a second transmission path different from the first transmission path.

  According to this, in the optical communication system, at a time point before a time point when a failure actually occurs in the first transmission path (for example, the number of error corrections in the error correction process becomes larger than a predetermined threshold). The operation transmission path can be changed. As a result, it is possible to prevent the receiving device from receiving erroneous data (that is, data different from the data transmitted from the transmitting device).

  That is, according to the optical communication system, it is possible to prevent the communication quality from being deteriorated when the operation transmission path is changed due to the occurrence of a failure.

(Appendix 2)
An optical communication system according to appendix 1,
The fluctuation quality value acquisition means detects a SOP (State of Polarization) vector locus length, which is a length of a locus drawn by a Stokes vector on a Poincare sphere within a wavelength band of the optical signal, or a value of a degree of polarization. An optical communication system configured to acquire the first variation quality value based on the detected value.

  By the way, the SOP vector locus length and the polarization degree are strongly correlated with the first variation quality value. Therefore, by configuring the optical communication system as described above, the first variation quality value can be obtained with high accuracy.

  In addition, when a value representing the quality of an optical signal is obtained based on the number of error corrections in forward error correction (FEC) processing or a code error rate (BER), an optical signal representing data ( That is, a modulated optical signal (modulated light) is required. On the other hand, when a value representing the quality of an optical signal is acquired based on the SOP vector locus length or the degree of polarization, modulated light, continuous wave (CW), or amplified spontaneous emission (ASE) is obtained. Amplified Spontaneous Emission) light can be used.

  Therefore, for example, when acquiring a value representing the quality of an optical signal in a transmission path that is not set as an operational transmission path, it is easier than using modulated light by using CW light or ASE light. A value representing the quality of the optical signal can be obtained.

  Furthermore, when the first variation quality value is acquired based on the SOP vector locus length, it is not necessary to provide a different device for each wavelength of the optical signal. Therefore, even if the optical communication system is configured to perform wavelength division multiplexing (WDM), it is possible to avoid an excessive cost for manufacturing the optical communication system. it can.

(Appendix 3)
An optical communication system according to appendix 1 or appendix 2,
The failure occurrence detection means is configured such that a ratio of the total time when the acquired first variation quality value becomes smaller than a preset quality threshold within a preset judgment period to the judgment period is If the time ratio of change of the acquired first variation quality value is a negative value when the ratio is equal to or greater than a preset ratio threshold, a failure is detected in the first transmission path. An optical communication system configured as described above.

  By the way, the first variation quality value often falls below a threshold value at which a failure occurs as a result of decreasing while vibrating. Therefore, by configuring the optical communication system as described above, it is possible to detect that a failure occurs at a time point before the time point when the first variation quality value actually falls below the threshold value.

(Appendix 4)
An optical communication system according to appendix 1 or appendix 2,
When the state in which the time variation rate of the acquired first variation quality value is a negative value continues for a predetermined threshold time or more, the failure occurrence detection unit is configured to perform the first transmission path. An optical communication system configured to detect the occurrence of a failure in the network.

  By the way, the first variation quality value often falls below a threshold value at which a failure occurs as a result of vibration while increasing the amplitude. Therefore, by configuring the optical communication system as described above, it is possible to detect that a failure occurs at a time point before the time point when the first variation quality value actually falls below the threshold value.

(Appendix 5)
An optical communication system according to appendix 3 or appendix 4,
The failure occurrence detection means is configured to acquire a time change rate of a value obtained by smoothing the acquired first variation quality value as a time change rate of the first variation quality value. .

  By the way, the acquired first variation quality value includes a measurement error and / or a minute variation component caused by noise light. Therefore, by configuring the optical communication system as described above, it is possible to reduce the influence of minute fluctuation components on the temporal change rate of the first fluctuation quality value. As a result, the time change rate of the first variation quality value can be acquired with high accuracy.

(Appendix 6)
An optical communication system according to any one of appendices 1 to 5,
Until the first transmission path is set as the operational transmission path and a failure is detected in the first transmission path, data is transmitted via the second transmission path. An optical communication system configured to stop supplying power for transmission and start supplying power when it is detected that a failure occurs in the first transmission path.

  According to this, even when the first transmission path is set as the operation transmission path, compared with the case where power for transmitting data is supplied via the second transmission path, the optical transmission path The amount of power consumed by the communication system can be reduced.

(Appendix 7)
An optical communication system according to any one of appendices 1 to 5,
The variation quality value acquisition unit is a time variation component caused by polarization mode dispersion among values representing the quality of the optical signal received by the reception device via the second transmission path. Configured to obtain a variable quality value of 2;
The failure occurrence detection means is configured to detect occurrence of a failure in the second transmission path based on the acquired second variation quality value,
The data transmission means detects the operation transmission path when it is detected that a failure has occurred in the first transmission path, and a failure has not been detected in the second transmission path. An optical communication system configured to change the first transmission path to the second transmission path.

  According to this, it is possible to avoid the occurrence of a failure in the second transmission path immediately after changing the operation transmission path. As a result, the optical communication system can reliably transmit data from the transmission device to the reception device.

(Appendix 8)
The optical communication system according to appendix 7,
Until the first transmission path is set as the operational transmission path and a failure is detected in the first transmission path, data is transmitted via the second transmission path. Configured to stop supplying power to the transmitter to transmit power,
The fluctuation quality value acquisition unit acquires the second fluctuation quality value based on noise light received by the receiving apparatus and output from an optical amplifier arranged in the second transmission path. An optical communication system configured.

  According to this, even when the first transmission path is set as the operation transmission path, compared with the case where power for transmitting data via the second transmission path is supplied to the transmission apparatus. Thus, the amount of power consumed by the optical communication system can be reduced.

(Appendix 9)
In addition to including a transmission device and a reception device, it is applied to an optical communication system that transmits data by optical signals from the transmission device to the reception device,
A first transmission path that is one of a plurality of transmission paths from the transmission apparatus to the reception apparatus is set as an operation transmission path, and the reception is performed from the transmission apparatus via the set operation transmission path. Transmitting the data to the device,
A first fluctuation quality value, which is a time fluctuation component caused by polarization mode dispersion, is acquired from values representing the quality of the optical signal received by the reception device via the first transmission path. ,
Detecting that a failure occurs in the first transmission path at a future time point based on the acquired first variation quality value;
When it is detected that a failure occurs in the first transmission path, the operation transmission path is different from the first transmission path from the first transmission path to the first transmission path. An optical communication method for changing to a second transmission path.

(Appendix 10)
The optical communication method according to appendix 9, wherein
The SOP (State of Polarization) vector trajectory length, which is the length of the trajectory drawn by the Stokes vector on the Poincare sphere within the wavelength band of the optical signal, or the value of the degree of polarization is detected, and based on the detected value An optical communication method for acquiring the first variation quality value.

(Appendix 11)
The optical communication method according to appendix 9 or appendix 10, wherein
The ratio of the total time that the acquired first variation quality value is smaller than the preset quality threshold within the preset judgment period to the judgment period is a preset ratio threshold. An optical communication method that detects the occurrence of a failure in the first transmission path when the time variation rate of the acquired first variation quality value is a negative value.

(Appendix 12)
The optical communication method according to appendix 9 or appendix 10, wherein
When a state in which the time variation rate of the acquired first variation quality value is a negative value continues for a preset threshold time or more, a failure occurs in the first transmission path. Detecting the optical communication method.

(Appendix 13)
A fluctuation quality value acquisition unit that acquires a fluctuation quality value that is a time fluctuation component caused by polarization mode dispersion among values representing the quality of the optical signal when the optical signal is input;
Based on the obtained variation quality value, failure occurrence detection means for detecting occurrence of a failure in a transmission path through which the optical signal is transmitted at a future time point;
A failure detection apparatus comprising:

(Appendix 14)
The failure detection device according to attachment 13, wherein
The fluctuation quality value acquisition means detects a SOP (State of Polarization) vector locus length, which is a length of a locus drawn by a Stokes vector on a Poincare sphere within a wavelength band of the optical signal, or a value of a degree of polarization. A failure detection device configured to acquire the variation quality value based on the detected value.

(Appendix 15)
The failure detection device according to appendix 13 or appendix 14,
The failure occurrence detection means is configured such that a ratio of the total time when the acquired variation quality value is smaller than a preset quality threshold within a preset judgment period to the judgment period is preset. And a failure detection device configured to detect that a failure occurs in the transmission path when the time variation rate of the acquired variation quality value is a negative value.

(Appendix 16)
The failure detection device according to appendix 13 or appendix 14,
The failure occurrence detection means causes a failure in the transmission path when the time variation rate of the obtained variation quality value is a negative value for a predetermined threshold time or more. A fault detection device configured to detect this.

(Appendix 17)
An optical signal is input, and a fluctuation quality value that is a time fluctuation component due to polarization mode dispersion is acquired from values representing the quality of the optical signal,
A failure detection method for detecting that a failure occurs in a transmission path through which the optical signal is transmitted at a future time point based on the acquired variation quality value.

(Appendix 18)
The failure detection method according to appendix 17,
The SOP (State of Polarization) vector trajectory length, which is the length of the trajectory drawn by the Stokes vector on the Poincare sphere within the wavelength band of the optical signal, or the value of the degree of polarization is detected, and based on the detected value A failure detection method for acquiring the fluctuation quality value.

(Appendix 19)
The failure detection method according to appendix 17 or appendix 18,
The ratio of the sum of times when the acquired variation quality value is smaller than a preset quality threshold within a preset judgment period is equal to or greater than a preset percentage threshold, A failure detection method that detects that a failure has occurred in the transmission path when the time variation rate of the obtained variation quality value is a negative value.

(Appendix 20)
The failure detection method according to appendix 17 or appendix 18,
Failure detection for detecting that a failure occurs in the transmission path when the time variation rate of the obtained variation quality value is a negative value continues for a preset threshold time or more. Method.

(Appendix 21)
In the failure detection device to which the optical signal is input,
Of the values representing the quality of the optical signal, a fluctuation quality value acquisition means for acquiring a fluctuation quality value that is a time fluctuation component caused by polarization mode dispersion;
Based on the obtained variation quality value, failure occurrence detection means for detecting occurrence of a failure in a transmission path through which the optical signal is transmitted at a future time point;
A program to realize

(Appendix 22)
The program according to attachment 21, wherein
The fluctuation quality value acquisition means detects a SOP (State of Polarization) vector locus length, which is a length of a locus drawn by a Stokes vector on a Poincare sphere within a wavelength band of the optical signal, or a value of a degree of polarization. A program configured to acquire the variation quality value based on the detected value.

(Appendix 23)
The program according to appendix 21 or appendix 22,
The failure occurrence detection means is configured such that a ratio of the total time when the acquired variation quality value is smaller than a preset quality threshold within a preset judgment period to the judgment period is preset. A program configured to detect that a failure occurs in the transmission path when the time variation rate of the obtained variation quality value is a negative value.

(Appendix 24)
The program according to appendix 21 or appendix 22,
The failure occurrence detection means causes a failure in the transmission path when the time variation rate of the obtained variation quality value is a negative value for a predetermined threshold time or more. A program configured to detect that.

  The present invention can be applied to an optical communication system or the like that transmits data using an optical signal from a transmission device to a reception device.

1000 Optical communication system 1001, 1002, 1003 Node devices 1004, 1005, 1006 Optical fibers 1007, 1008, 1009 Optical amplifiers 1010, 1011 Optical demultiplexers 1012 and 1013 Optical signal quality monitor 1015 Polarizers 4001, 4002 Optical transmitter 4003 4004 Optical receiver 4005 Optical switch 5000 Optical communication system 5001, 5002, 5003 Node device 5004, 5005, 5006 Optical fiber 5007, 5008, 5009 Optical amplifier 5010, 5011 Optical demultiplexer 5012, 5013 Optical signal quality monitor 5015 Polarizer 5017 , 5018 Wavelength multiplexer 5019, 5020 Wavelength separator 5021-5028 Optical receiver 5031-5038 Optical transmitter 7000 Optical communication system 7001 Data transmission unit 7002 Variable product Value acquisition unit 7003 failure detection unit

Claims (10)

An optical communication system that includes a transmission device and a reception device, and transmits data from the transmission device to the reception device by an optical signal,
A plurality of transmission paths from the transmitting device to the receiving device;
Data that sets a first transmission path, which is one of the plurality of transmission paths, as an operating transmission path, and transmits the data from the transmitting apparatus to the receiving apparatus via the set operating transmission path Transmission means;
Of the values representing the quality of the optical signal received by the receiving device via the first transmission path, a first variation quality value that is a time variation component due to polarization mode dispersion is acquired. A variable quality value acquisition means;
A failure occurrence detection means for detecting that a failure occurs in the first transmission path at a future time point based on the acquired first variation quality value;
With
When it is detected that a failure occurs in the first transmission path, the data transmission means changes the operation transmission path from the first transmission path to the first transmission path among the plurality of transmission paths. An optical communication system configured to change to a second transmission path different from the first transmission path. The optical communication system according to claim 1,
The fluctuation quality value acquisition means detects a SOP (State of Polarization) vector locus length, which is a length of a locus drawn by a Stokes vector on a Poincare sphere within a wavelength band of the optical signal, or a value of a degree of polarization. An optical communication system configured to acquire the first variation quality value based on the detected value. The optical communication system according to claim 1 or 2,
The failure occurrence detection means is configured such that a ratio of the total time when the acquired first variation quality value becomes smaller than a preset quality threshold within a preset judgment period to the judgment period is If the time ratio of change of the acquired first variation quality value is a negative value when the ratio is equal to or greater than a preset ratio threshold, a failure is detected in the first transmission path. An optical communication system configured as described above. The optical communication system according to claim 1 or 2,
When the state in which the time variation rate of the acquired first variation quality value is a negative value continues for a predetermined threshold time or more, the failure occurrence detection unit is configured to perform the first transmission path. An optical communication system configured to detect the occurrence of a failure in the network. An optical communication system according to claim 3 or claim 4,
The failure occurrence detection means is configured to acquire a time change rate of a value obtained by smoothing the acquired first variation quality value as a time change rate of the first variation quality value. . An optical communication system according to any one of claims 1 to 5,
Until the first transmission path is set as the operational transmission path and a failure is detected in the first transmission path, data is transmitted via the second transmission path. An optical communication system configured to stop supplying power for transmission and start supplying power when it is detected that a failure occurs in the first transmission path. An optical communication system according to any one of claims 1 to 5,
The variation quality value acquisition unit is a time variation component caused by polarization mode dispersion among values representing the quality of the optical signal received by the reception device via the second transmission path. Configured to obtain a variable quality value of 2;
The failure occurrence detection means is configured to detect occurrence of a failure in the second transmission path based on the acquired second variation quality value,
The data transmission means detects the operation transmission path when it is detected that a failure has occurred in the first transmission path, and a failure has not been detected in the second transmission path. An optical communication system configured to change the first transmission path to the second transmission path. The optical communication system according to claim 7,
Until the first transmission path is set as the operational transmission path and a failure is detected in the first transmission path, data is transmitted via the second transmission path. Configured to stop supplying power to the transmitter to transmit power,
The fluctuation quality value acquisition unit acquires the second fluctuation quality value based on noise light received by the receiving apparatus and output from an optical amplifier arranged in the second transmission path. An optical communication system configured. In addition to including a transmission device and a reception device, it is applied to an optical communication system that transmits data by optical signals from the transmission device to the reception device,
A first transmission path that is one of a plurality of transmission paths from the transmission apparatus to the reception apparatus is set as an operation transmission path, and the reception is performed from the transmission apparatus via the set operation transmission path. Transmitting the data to the device,
A first fluctuation quality value, which is a time fluctuation component caused by polarization mode dispersion, is acquired from values representing the quality of the optical signal received by the reception device via the first transmission path. ,
Detecting that a failure occurs in the first transmission path at a future time point based on the acquired first variation quality value;
When it is detected that a failure occurs in the first transmission path, the operation transmission path is different from the first transmission path from the first transmission path to the first transmission path. An optical communication method for changing to a second transmission path. A fluctuation quality value acquisition unit that acquires a fluctuation quality value that is a time fluctuation component caused by polarization mode dispersion among values representing the quality of the optical signal when the optical signal is input;
Based on the obtained variation quality value, failure occurrence detection means for detecting occurrence of a failure in a transmission path through which the optical signal is transmitted at a future time point;
A failure detection apparatus comprising:

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