WO2011118545A1 - Optical communication system - Google Patents

Abstract

Provided is an optical communication system whereby, when the working transmission path is to be changed to another transmission path because of occurrence of a trouble, the degradation of communication quality can be avoided. An optical communication system, which is operative to transmit an optical signal from a transmitter apparatus to a receiver apparatus via a working transmission path that is one of a plurality of transmission paths, comprises: a variable quality value acquiring means for acquiring, out of values representative of the quality of the optical signal received by the receiver apparatus via the working transmission path, a first variable quality value that is a time-variable component caused by a polarized-wave mode spread; a trouble occurrence detecting means for detecting, based on the first variable quality value, that a trouble will occur on the working transmission path at a time point in the future and for outputting a trouble occurrence warning signal; and a data transmitting means operative to change the working transmission path to another transmission path when having received the trouble occurrence warning signal.

Description

Optical communication system

The present invention relates to an optical communication system for transmitting data from a transmitter to a receiver by an optical signal.

An optical communication system is known which transmits data from a transmitter to a receiver by an optical signal. The optical communication system described in Patent Document 1 as one of such optical communication systems has a plurality of transmission paths from the transmitting device to the receiving device.
The optical communication system sets the first transmission path as an operation transmission path, and transmits data from the transmitter to the receiver 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 becomes larger than a predetermined threshold. . When the optical communication system detects that a failure has occurred in the first transmission path, the optical communication system changes (switches) the operation transmission path from the first transmission path to the second transmission path.
Thus, the optical communication system can accurately transmit data using the second transmission path even when a failure occurs in the first transmission path.

JP, 2005-260820, A Unexamined-Japanese-Patent No. 2006-352680

However, the above optical communication system has the following problems. That is, accurate data (that is, the same data as data transmitted from the transmitting apparatus) in a period from when it is detected that a failure occurs in the first transmission path to when switching of the operation transmission path is completed. Can not be received by the receiving device. As a result, there is a problem that communication quality is degraded.
In particular, as the amount of data transmitted per unit time increases, the amount of data received by the receiving device in the above period increases. Therefore, the larger the amount of data transmitted per unit time, the more noticeable the above problem.
(Object of the Invention)
An object of the present invention is an optical communication system capable of solving the above-mentioned problem “when communication quality is lowered when changing an operation transmission path due to occurrence of a failure”. Intended to be provided.

An optical communication system according to the present invention is an optical communication system for transmitting an optical signal from a transmitter to a receiver via an operation transmission path which is any of a plurality of transmission paths,
Fluctuation quality for acquiring a first fluctuation quality value which is a time fluctuation component caused by polarization mode dispersion among values representing the quality of the optical signal received by the receiving apparatus through the operation transmission line Value acquisition means,
Failure occurrence detection means for detecting occurrence of a failure in the operation transmission path at a future time based on the first variation quality value, and outputting a failure occurrence warning signal;
It includes data transmission means for changing the operation transmission path to another transmission path when the failure occurrence alarm signal is input.
The optical communication method of the present invention is applied to an optical communication system for transmitting an optical signal from a transmitter to a receiver via an operation transmission path which is any of a plurality of transmission paths,
Acquiring a first fluctuation quality value, which is a time fluctuation component caused by polarization mode dispersion, among values representing the quality of the optical signal received by the receiving apparatus through the operation transmission line;
Based on the first variation quality value, it is detected that a failure occurs in the operation transmission path at a future time, and a failure occurrence warning signal is output,
When the failure occurrence alarm signal is input, the operation transmission path is changed to another transmission path.
The fault detection apparatus according to the present invention receives a light signal and obtains a fluctuation quality value that acquires a fluctuation quality value that is a time fluctuation component caused by polarization mode dispersion among values representing the quality of the light signal. Means,
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 based on the acquired fluctuation quality value;
Equipped with

The present invention is configured as described above, so that it is possible to prevent the communication quality from being lowered when changing the operation transmission path in accordance with the occurrence of a failure.

It is a figure showing schematic structure of the optical communication system concerning 1st Embodiment of this invention. It is the graph which showed an example of the time change of the fluctuation quality value. It is the graph which showed the time change of the value which smooth | blunted the fluctuation | variation quality value shown in FIG. It is the block diagram which showed the structure of each node apparatus 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 a graph showing an example of the relation between SOP vector locus length and change 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 apparatus, a failure detection method, and a program according to the present invention will be described with reference to FIGS. 1 to 7.
(Summary of the embodiment)
The optical communication system according to each embodiment of the present invention has a plurality of transmission paths for transmitting data by an optical signal. The plurality of transmission paths include a first transmission path and a second transmission path from the transmitter to the receiver. The optical communication system sets a first transmission path or a second transmission path as an operation transmission path, and transmits data from the transmitter to the receiver via the operation transmission path.
The optical communication system has a fluctuation quality that is a value that well reflects the time fluctuation component caused by polarization mode dispersion among the values representing the quality of the optical signal that has passed through the first transmission path set as the operation transmission path. Get the value. The variable quality value will be further described later. The optical communication system detects that a failure occurs in the first transmission path at a future time based on the acquired variable quality value (ie, 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 failure actually occurs. . This can 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 to be transmitted per unit time becomes larger (that is, the capacity of the communication service becomes larger), the receiving apparatus takes a period from the actual occurrence of the failure until the change of the operation transmission path is completed. The amount of data received increases. Therefore, the further effect is exhibited by this embodiment.
In other words, by shortening the period (that is, the time during which the communication service is disconnected (blocked)), retransmission control of data accompanying the loss of data to be transmitted is suppressed, and the communication service can be further speeded up. can do. In addition, if the above period does not exist (the period is zero), the optical communication system is determined as if the failure does not occur although the failure is actually occurring. It 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, physical phenomena such as wavelength dispersion, polarization dispersion, optical S / N (Signal-to-Noise), and nonlinear distortion are factors that cause the quality of the optical signal to fluctuate. Conceivable. Among them, a particularly important factor is polarization mode dispersion (PMD).
The reason for this is that the fluctuation in quality caused by PMD is irregular and is a high speed phenomenon, so it is difficult to suppress the fluctuation in quality by performing compensation or the like. On the other hand, since other factors are relatively regular and slow phenomena, it is possible to suppress the fluctuation of quality by performing compensation or the like. Therefore, the fluctuation of the quality of the optical signal is dominated by the part caused by PMD. That is, it is particularly important to monitor quality variations due to PMD.
By the way, when a failure occurs due to PMD, the failure often occurs because the quality of the optical signal is rapidly degraded during a very short time (ie, instantaneously). In such a case, monitoring of only the time-varying component caused by PMD among the values representing the quality of the optical signal is more likely to cause a failure 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, among the values representing the quality of the optical signal, a fluctuation quality value which is a time fluctuation component caused by polarization mode dispersion, and based on the fluctuation quality value, at a future time, Detect when a failure occurs.
The variable quality value will be further described. In order to monitor the quality of a signal, a bit error rate (BER) or a number of error corrections in forward error correction (FEC) processing is often used.
However, the number of error corrections in BER or FEC processing does not necessarily reflect only the fluctuation quality due to PMD. Therefore, the optical communication system detects the SOP (State of Polarization) vector locus length or the degree of polarization that strongly correlates with the fluctuation quality due to PMD, and based on the detected value, the fluctuation quality due to PMD We will acquire the fluctuation quality value as a value that reflects well. The SOP vector locus length is the length of the locus drawn by the Stokes vector on the Poincare sphere in the wavelength band of the optical signal. The degree of polarization is also called DOP (Degree of Polarization). However, the fluctuation quality value is not limited to the above as long as it is a value that well reflects the fluctuation of quality caused by PMD, and even a value well reflecting the fluctuation of quality caused by PMD. Anything will do. The occurrence of a failure can be predicted with high accuracy by using the variable quality value having such a feature.
Also, when acquiring a value representing the quality of the optical signal based on the number of error corrections in the FEC processing or the code error rate, the optical signal representing the data (ie, the modulated optical signal (modulated light)) Is required. On the other hand, when obtaining a value representing the quality of the optical signal based on the SOP vector locus length or the degree of polarization, modulated light, continuous wave (CW: continuous wave) light, or amplified spontaneous emission (ASE: 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 (backup transmission path) not set as an operation transmission path, the following advantages can be obtained by using CW light or ASE light: There is. That is, the value representing the quality of the optical signal can be obtained more easily than in the case of using modulated light. Therefore, by using a simple light source, it is possible to obtain a value representing the quality of the light signal. As a result, equipment and operation costs can be reduced to predict the occurrence of a failure in the backup transmission path.
Also, in an optical communication system, a hot standby method is often used in which power for transmitting data is supplied in advance via a spare transmission path. The reason is that it is difficult to handle complicated control protocols, and because the time taken for the transmission apparatus (optical transmission apparatus) to operate stably is relatively long. However, the hot standby method has a problem that the operation cost and the power consumption amount are large as compared with the cold standby method in which the supply of power for transmitting data is stopped via the spare transmission path.
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 when it is detected that a failure will occur in the future, to when the failure actually occurs. Therefore, even if power for transmitting data is not supplied in advance via the spare transmission path, preparation for transmission of data via the spare transmission path is completed by the time a failure actually occurs. be able to.
Therefore, in the optical communication system according to one of the embodiments of the present invention, it is possible to transmit power through the spare transmission path until it is detected that a failure occurs in the operation transmission path. Stop the supply. 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, it is possible to increase the reliability of the optical communication system, speed up the communication service, reduce the facility and operation cost of the optical communication system, and reduce the power consumption. It becomes possible to realize.
First Embodiment
(Constitution)
As shown in FIG. 1, the optical communication system 1000 according to the first embodiment includes a plurality of (three in this example) node devices (communication devices) 1001, 1002, and 1003. In this example, the node device 1001 is also referred to as a transmitting device. The node device 1002 is also referred to as a receiving device. Also, the node device 1001 and the node device 1002 constitute data transmission means.
The node device 1001 is connected to the node device 1002 via an 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 device 1002 from the node device 1001 via the optical fiber 1004 is also referred to as a first transmission path. The transmission path of the optical signal that reaches the node device 1002 from the node device 1001 via the optical fiber 1005, the node device 1003, and the optical fiber 1006 is also referred to as a second transmission path. Thus, the optical communication system 1000 has a plurality of transmission paths consisting of 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 an output control signal from the node device 1002, and outputs an optical signal to any one of the optical fiber 1004 and the optical fiber 1005 according to the output control signal. The output control signal indicates that the first transmission path or the second transmission path is to be set as an operation transmission path.
The node device 1003 receives an 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 is an optical signal transmitted by the node device 1001, and receives an optical signal transmitted via the first transmission path or the second transmission path.
Also, the optical communication system 1000 includes a plurality of (three in this example) optical amplifiers (optical amplifiers) 1007, 1008, and 1009, and a polarizer 1015.
The optical amplifier 1007 is disposed in 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 in 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 the polarization state to the optical fiber 1005.
The optical signal transmitted by the node device 1001 is received by the node device 1002 after the quality is changed due to various factors while being transmitted via the transmission path.
Furthermore, the optical communication system 1000 includes a plurality of (two in this example) optical splitters 1010 and 1011 and a plurality of (two in this example) optical signal quality monitors (fault detection devices) 1012 and 1013, Equipped with The optical signal quality monitor 1013 constitutes fluctuation quality value acquisition means and failure occurrence detection means.
The optical splitter 1010 is disposed at the end of the optical fiber 1006 on the node device 1002 side. The optical splitter 1010 splits the optical signal transmitted by the optical fiber 1006 and monitors the branched optical signal (that is, the optical signal received by the receiver 1002 via the second transmission path) as an optical signal quality monitor Output to 1012
Similarly, the optical splitter 1011 is disposed at the end of the optical fiber 1004 on the node device 1002 side. The optical splitter 1011 branches the optical signal transmitted by the optical fiber 1004, and monitors the branched optical signal (that is, the optical signal received by the receiver 1002 via the first transmission path) as an optical signal quality monitor Output to 1013
The optical signal quality monitor 1012 is a fluctuation quality value that is a time fluctuation component caused by polarization mode dispersion among values representing the quality of the input optical signal (that is, the optical signal passed through the second transmission path). Get (the second variation quality value). In this example, the optical signal quality monitor 1012 measures (detects) the SOP vector locus length, and acquires the measured value itself or a value obtained by performing a predetermined operation on the value as a fluctuation quality value. The optical signal quality monitor 1012 may detect the degree of polarization and acquire the detected value itself or a value obtained by performing a predetermined operation on the value as the fluctuation quality value.
Specifically, the optical signal quality monitor 1012 stores information representing the relationship between the SOP vector locus length and the fluctuation quality value based on the experimentally measured values. Then, the optical signal quality monitor 1012 obtains the fluctuation quality value from the measured SOP vector locus length and the stored information.
The optical signal quality monitor 1012 may acquire, based on the SOP vector locus length or the degree of polarization (DOP), a temporal fluctuation component caused by PMD among values representing the quality of the optical signal. This method is disclosed, for example, in Japanese Patent Laid-Open No. 2009-260875.
The optical signal quality monitor 1012 outputs a failure occurrence warning signal to the node device 1002 when the acquired 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 caused by polarization mode dispersion among values representing the quality of the input optical signal (that is, the optical signal passed through the first transmission path). Get (the first variation quality value). The optical signal quality monitor 1013 outputs a failure occurrence warning signal to the node device 1002 when the acquired fluctuation quality value satisfies the above detection condition.
When receiving the failure occurrence warning signal, the node device 1002 changes the transmission path set as the operation transmission path.
That is, when the node device 1002 receives the 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 device 1002 transmits the operation transmission path from the first transmission path to the second transmission path. Change to the transmission path of Specifically, the node device 1002 transmits, to the node device 1001, an output control signal indicating that the second transmission path is to be set as an operation transmission path.
When the node device 1002 receives the failure occurrence warning signal from the optical signal quality monitor 1012 when the second transmission path is set as the operation transmission path, the node device 1002 transmits the operation transmission path from the second transmission path to the second transmission path. Change to the transmission path of 1. Specifically, the node device 1002 transmits, to the node device 1001, an output control signal indicating that the first transmission path is to be set as an operation transmission path.
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 time change of fluctuation quality value which is a time fluctuation component caused by polarization mode dispersion among values representing the quality of an optical signal. In the present example, it is assumed that a failure actually occurs when the fluctuation quality value falls below the quality deterioration threshold Qth after time t2. Note that occurrence of a fault corresponds to, for example, the fact that the number of error corrections in the FEC process becomes larger than a preset threshold. Also, the quality deterioration threshold Qth is a threshold of a fluctuation quality value at which a failure actually occurs.
By the way, as described above, PMD is dominant in the factor that causes the quality of the optical signal to fluctuate. In addition, PMD fluctuates the quality of the optical signal irregularly and at high speed. For this reason, as shown in FIG. 2, at the normal time (that is, at a time point before time t1), although the fluctuation quality value has a value sufficiently larger than the quality deterioration threshold Qth, May cause such problems. That is, there is a problem that the fluctuation quality value may drop sharply during a relatively short time (during the period between time t1 and time t2) and fall below the quality deterioration threshold Qth.
In the example shown in FIG. 2, the fluctuation quality value vibrates and decreases during the time t1 and the time t2, and the amplitude of the vibration is increased and finally falls below the quality deterioration threshold Qth after t2.
Therefore, each of the optical signal quality monitors 1012 and 1013 detects that a failure will occur in the future in the transmission path to be detected in the following case, within the judgment period set in advance. That is, the ratio of the total of time when the fluctuation quality value becomes smaller than the preset quality threshold to the determination period becomes equal to or more than the preset threshold (ratio threshold), and the fluctuation quality value at that time If the time rate of change is a negative value. Note that “at that point” means that the ratio of the total of times when the fluctuation quality value becomes smaller than the preset quality threshold to the determination period is equal to or greater than the preset threshold (percentage threshold). It means that.
Thereby, it is possible to detect that a failure occurs at a time before the time when the fluctuation quality value actually falls below the quality degradation threshold Qth.
Specifically, each of the optical signal quality monitors 1012 and 1013 starts measuring the time by the timer when the acquired fluctuation quality value falls below the PMD-induced quality fluctuation threshold Qpmd (quality threshold). That is, it is the time when the acquired fluctuation quality value becomes smaller than the PMD-induced quality fluctuation threshold Qpmd. 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 starts the measurement of the time by the timer, and in the period (determination period) until the time measured by the timer exceeds the time threshold T set in advance, Do. That is, the sum of time in which the acquired fluctuation quality value becomes smaller than the PMD-induced quality fluctuation threshold Qpmd (that is, falls below the PMD-induced quality fluctuation 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 the time threshold T (that is, the length of the determination period). That is, the value R is a ratio of the total to the determination period.
On the other hand, each of the optical signal quality monitors 1012 and 1013 calculates the time change rate (that is, time differential value) Q ′ of the fluctuation quality value. By the way, the fluctuation quality value acquired includes a measurement error and / or a minute fluctuation component due to noise light. For this reason, there is a possibility that the time change rate of the fluctuation quality value can not 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 acquired fluctuation quality value as the time change rate of the fluctuation quality value. Here, FIG. 3 is a graph showing the time change of the value obtained by smoothing the fluctuation quality value shown in FIG.
In this example, each of the optical signal quality monitors 1012 and 1013 smoothes the obtained fluctuation quality value by using a low pass filter. Each of the optical signal quality monitors 1012 and 1013 may be configured to use a Savitzky-Golay filter.
As a result, it is possible to reduce the influence of measurement errors and / or minute fluctuation components due to noise light on the time rate of change of fluctuation quality values. As a result, it is possible to obtain the temporal change rate of the fluctuation quality value with high accuracy.
Each of the optical signal quality monitors 1012 and 1013 detects that a failure will occur in the future in the transmission path to be detected in the following case. That is, the calculated value R is equal to or greater than a preset ratio threshold Rth, and the calculated time change rate Q ′ of the fluctuation quality value is a negative value. The condition that the value R is equal to or greater than the ratio threshold Rth and the time rate of change Q ′ of the fluctuation quality value is a negative value is also referred to as a detection condition. 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 of the optical signal quality monitors 1012 and 1013 outputs a failure occurrence warning signal to the node device 1002 when it is detected that a failure will occur at a future time point in the transmission path to be detected.
Here, among the values representing the quality of the optical signal, the effect in the case of predicting the occurrence of a fault by using a fluctuation quality value which is a time fluctuation component caused by polarization mode dispersion, in BER or FEC processing Description will be made in comparison with the case where the number of error corrections is used.
When 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 differences between the PMD-induced quality fluctuation threshold Qpmd and the quality fluctuation threshold Qber are as follows. That is, while the PMD-induced quality variation threshold Qpmd is a value based on only the time variation component among the values representing the quality, the quality variation threshold Qber is not only the time variation component but also a fixed component that hardly changes. Is also a point based on.
That is, assuming that the value representing the quality of the optical signal is Q (t), it is assumed that Q (t) is the sum of time-varying component ΔQ (t) and component Q0 which hardly changes at normal times. I can think of it. That is, Q (t) = ΔQ (t) + Q0.
By the way, when PMD is dominant as a factor that the quality of the optical signal fluctuates, the PMD-induced quality fluctuation threshold Qpmd is substantially a threshold for ΔQ (t), while the quality fluctuation threshold Qber is substantially Threshold for Q (t).
Also, the fluctuation range of ΔQ (t) can be estimated relatively accurately from the PMD characteristics in the transmission path. Therefore, it is relatively easy to set the value of the PMD-induced quality fluctuation threshold Qpmd properly.
However, it is difficult to accurately estimate the fluctuation range of Q (t), since Q0 changes depending on various characteristics such as the transmission path and the node device. For this reason, it is difficult to set the value of the quality variation threshold Qber properly.
Therefore, it is effective to use the SOP vector locus length or the degree of polarization (DOP) which can extract only the time-varying component due to PMD among the values representing the quality of the optical signal.
Each of the optical signal quality monitors 1012 and 1013 indicates that the state in which the time change rate of the acquired fluctuation quality value is a negative value continues for a predetermined time (time threshold) or more. At this point, it may be configured as follows. That is, it is configured to detect that a fault occurs in the transmission path to be detected. This also makes it possible to detect that a failure occurs at a time before the time when the variation 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.
Thus, data is transmitted from the node device 1001 to the node device 1002.
The optical signal quality monitor 1013 also receives the optical signal output by the optical splitter 1011. Then, the optical signal quality monitor 1013 obtains a first fluctuation quality value which is a time fluctuation component caused by polarization mode dispersion among values representing the quality of the input optical signal.
The optical signal quality monitor 1013 determines whether the acquired first variation quality value satisfies the detection condition. Now, it is assumed that the light signal quality monitor 1013 determines that the acquired first variation 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.
As a result, the optical signal transmitted by the node device 1001 subsequently 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 is at a time before the time when a failure actually occurs in the first transmission path. Can change the operation transmission path. This is the case, for example, when the number of error corrections in the error correction process becomes larger than a predetermined threshold. As a result, it is possible to prevent the node device 1002 (receiving device) from receiving erroneous data (that is, data different from the data transmitted from the node device 1001 (transmitting device)).
That is, according to the optical communication system 1000, it is possible to prevent the communication quality from being degraded when changing the operation transmission path in accordance with the occurrence of the failure.
First Modified Example of First Embodiment
Next, a first modified example of the first embodiment will be described. The optical communication system according to the first modification differs from the optical communication system according to the first embodiment in that the supply of power related to the spare transmission path is stopped until occurrence of an abnormality is detected. ing. Therefore, the following description will be focused 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 of (two in this example) 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 of (in this example, two) optical receivers 4003 and 4004. The optical receiver 4003 receives (inputs) an optical signal that has passed through the optical fiber 1004. The optical receiver 4004 receives (inputs) an optical signal that has passed through the optical fiber 1006.
The node device 1003 includes an optical switch 4005. The optical switch 4005 outputs the input optical signal without termination. The optical switch 4005 is configured to be able 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 to simplify the description.
By the way, in general, in the optical communication system, the 1 + 1 protection method, which is a hot standby method, is used as a switching method of a transmission path when a failure occurs. The reason is that it is difficult to perform processing based on a complicated control protocol in the optical communication system, and it takes a relatively long time for the node device to operate stably.
By the way, when using the 1 + 1 protection scheme, it is necessary to always prepare a backup transmission path equivalent to the operation transmission path. Therefore, while supplying power for transmitting data via the spare transmission path even during normal times, the same optical signal as the optical signal transmitted via the operation transmission path is used as the spare transmission path. It must also be transmitted via
As a result, the facility cost for providing a dedicated spare transmission path for one operation transmission path, and the operation cost for always operating the spare transmission path in addition to the operation transmission path are required. By detecting the occurrence of a fault in advance, if it is possible to secure a relatively long application time until the fault actually occurs, it is not necessary to always operate the spare transmission path.
This is because, at a time before the failure actually occurs, the occurrence of the failure is detected, and preparation for changing the operation transmission path (for example, supply of power for the spare transmission path) is started. Because you can do it.
Therefore, the optical communication system 1000 according to the first modification stops the supply of power for transmitting data via the second transmission path in the following case. That is, it is in a period until the first transmission path is set as the operation transmission path and it is detected that a failure occurs in the first transmission path. Specifically, the optical communication system 1000 stops (shuts off) the supply of power 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 a 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.
Then, the node device 1002 transmits an output control signal to the node device 1001 after a standby time set in advance has elapsed since the point in time when the failure occurrence warning signal was received from the optical signal quality monitor 1013.
According to the optical communication system 1000 according to the first modification, power is provided to transmit data via the second transmission path even while the first transmission path is set as the operation transmission path. There are the following effects compared to the case where That is, the amount of power consumed by the optical communication system 1000 can be reduced.
Second Modified Example of First Embodiment
Next, a second modification of the first embodiment will be described. The optical communication system according to the second modification detects a failure in the spare transmission path based on the noise light output from the optical amplifier in the optical communication system according to the first embodiment. It is different. Therefore, the following description will be focused 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 of (two in this example) 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 of (in this example, two) optical receivers 4003 and 4004. The optical receiver 4003 receives (inputs) an optical signal that has passed through the optical fiber 1004. The optical receiver 4004 receives (inputs) an optical signal that has passed through the optical fiber 1006.
The node device 1003 includes an optical switch 4005. The optical switch 4005 outputs the input optical signal without termination. The optical switch 4005 is configured to be able 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 to simplify the description.
The optical communication system 1000 according to the second modification stops supply of power for transmitting data to the node device 1001 (transmitting device) via the second transmission path in the following case. That is, it is in a period until the first transmission path is set as the operation transmission path and it is detected that a failure occurs in the first transmission path. Specifically, the optical communication system 1000 stops (shuts off) the supply of power to the optical transmitter 4002.
The optical signal quality monitor 1012 receives the second fluctuation quality value from the noise light received by the optical receiver 4004 included in the node device 1002 and output from the optical amplifiers 1008 and 1009 arranged in the second transmission path. get. The node device 1002 is a receiving device.
According to this, even while the first transmission path is set as the operation transmission path, the power for transmitting data via the second transmission path is compared with the case where the power is supplied to the transmitting apparatus. The following effects can be obtained. That is, the amount of power consumed by the optical communication system 1000 can be reduced.
That is, even while the first transmission path is set as the operation transmission path, the amount of power consumed by the optical communication system 1000 can be reduced compared to the case where power is supplied to the optical transmitter 4002 .
Then, the node device 1002 transmits the output control signal to the node device 1001 when the failure occurrence warning signal is received from the optical signal quality monitor 1013 and the failure occurrence warning signal is not received from the light signal quality monitor 1012. Do.
That is, the node device 1002 can detect the occurrence of a failure in the first transmission path and can not output the output control signal to the node when the occurrence of the failure in the second transmission path is not detected. Send to the 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 (transmission device) to the node device 1002 (reception 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 of different wavelengths are superimposed on an optical fiber. . Therefore, the following description will be focused on such differences.
As shown in FIG. 5, the optical communication system 5000 according to the second embodiment includes node devices 5001, 2502, 5003 respectively corresponding to the node devices 1001, 1002, 1003 in FIG. 1. The optical communication system 5000 also includes optical fibers 5004, 5005, 5006 corresponding to the optical fibers 1004, 1005, 1006 in FIG. The optical communication system 5000 further includes optical amplifiers 5007, 5008, and 5009 respectively corresponding to the optical amplifiers 1007, 1008, and 1009 in FIG. The optical communication system 5000 further includes optical splitters 5010 and 5011 corresponding to the optical splitters 1010 and 1011 of FIG. The optical communication system 5000 further includes optical signal quality monitors 5012 and 5013 respectively corresponding to the optical signal quality monitors 1012 and 1013 of FIG. 1 and a polarizer 5015 corresponding to the polarizer 1015 of FIG.
Furthermore, the optical communication system 5000 includes wavelength multiplexers 5017 and 5018 and wavelength separators 5019 and 5020.
The node device 5001 includes a plurality of (eight in this example) optical transmitters 5031 to 5038.
Each of the optical transmitters 5031 to 5034 outputs an optical signal to the wavelength multiplexer 5018. The respective optical transmitters 5031 to 5034 output (transmit) optical signals having different wavelengths (in this example, λ 1, λ 2, λ 3 or λ 4). The wavelength multiplexer 5018 superimposes the input optical signal and outputs the optical signal to the optical amplifier 5008.
Similarly, each of the optical transmitters 5035 to 5038 outputs an optical signal to the wavelength multiplexer 5017. The respective optical transmitters 5035 to 5038 output (transmit) optical signals having different wavelengths (in this example, λ1, λ2, λ3, or λ4). The wavelength multiplexer 5017 superimposes the input optical signal and outputs the optical signal to the optical amplifier 5007.
The node device 5002 includes a plurality of (eight in this example) optical receivers 5021 to 5028.
The wavelength separator 5019 receives an optical signal (output from the optical amplifier 5007) transmitted via the first transmission path. The wavelength separator 5019 separates the input optical signal into optical signals for each wavelength, and outputs the separated optical signals to the optical receivers 5025 to 5028. The respective optical receivers 5025 to 5028 input (receive) optical signals having different wavelengths (in this example, λ 1, λ 2, λ 3 or λ 4).
The wavelength separator 5020 receives the optical signal (output from the optical amplifier 5009) transmitted via the second transmission path. The wavelength separator 5020 separates the input optical signal into optical signals for each wavelength, and outputs the separated optical signals to the optical receivers 5021 to 5024. The respective optical receivers 5021 to 5024 input (receive) optical signals having different wavelengths (in this example, λ 1, λ 2, λ 3 or λ 4).
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).
The optical signal quality monitor 5013, like the optical signal quality monitor 1013, is a fluctuation quality value that is a time fluctuation component caused by polarization mode dispersion among the values representing the quality of the optical signal that has passed through the first transmission path. Get (the first variation quality value). In the present example, the optical signal quality monitor 5013 measures (detects) the SOP vector trajectory length, and acquires the variation quality value based on the measured value.
FIG. 6 is a graph showing an example of the relationship between the SOP vector locus length and the variation 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 variation quality value based on the relationship between the SOP vector trajectory length and the variation quality value and the measured SOP vector trajectory length based on the measurement values obtained in advance by experiment. Do. Thereby, the variable quality value can be obtained with high accuracy.
By the way, 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 the fluctuation quality value for each wavelength based on the SOP vector locus length measured for each wavelength. That is, 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 acquiring the variation quality value based on the SOP vector locus length, it is not necessary to provide different devices 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 prevent the cost for manufacturing the optical communication system 5000 from becoming excessive.
As described above, according to the optical communication system 5000 according to the second embodiment of the present invention, the same operation and effect as 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 third embodiment is a system that includes a transmitter and a receiver, and transmits data from the transmitter to the receiver by an optical signal.
Furthermore, the optical communication system 7000 has a plurality of transmission paths from the transmitter to the receiver. Further, the optical communication system 7000 sets a first transmission path, which is one of the plurality of transmission paths, as an operation transmission path. Furthermore, the optical communication system 7000 includes a data transmission unit (data transmission unit) 7001 that transmits the data from the transmission apparatus to the reception apparatus via the set operation transmission path.
Furthermore, the optical communication system 7000 is a fluctuation quality value for acquiring a first fluctuation quality value among values representing the quality of the optical signal received by the receiving apparatus via the first transmission path. An acquisition unit (means) 7002 is provided.
The first variation quality value is a time variation component due to polarization mode dispersion.
Furthermore, the optical communication system 7000 detects a failure occurrence in the first transmission path at a future time based on the acquired first fluctuation quality value (a failure occurrence detection unit (a failure). Occurrence detection means) 7003 is provided.
The data transmission unit 7001 performs the following operation when it is detected that a failure occurs in the first transmission path. That is, the data transmission unit 7001 is configured to change the operation transmission path from the first transmission path to a second transmission path different from the first transmission path among the plurality of transmission paths. Be done.
According to this, in the optical communication system 7000, at the time before the time when the failure actually occurs in the first transmission path (for example, the number of error corrections in the error correction processing becomes larger than the predetermined threshold) , You can change the operation transmission path. 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, when the operation transmission path is changed in response to the occurrence of a failure, it is possible to prevent the communication quality from being degraded.
Fourth Embodiment
An optical communication system according to another aspect of the present invention is a system that includes a transmitter and a receiver, and transmits data from the transmitter to the receiver by an optical signal.
Furthermore, the optical communication system has a plurality of transmission paths from the transmitter to the receiver.
Further, the optical communication system sets a first transmission path, which is one of the plurality of transmission paths, as an operation transmission path.
The optical communication system further includes data transmission means for transmitting the data from the transmitting device to the receiving device via the set operation transmission path.
Furthermore, this optical communication system is characterized by a first fluctuation quality which is a time fluctuation component due to polarization mode dispersion among values representing the quality of the optical signal received by the receiving apparatus via the first transmission path. It has a variable quality value acquisition means for acquiring a value.
The optical communication system further includes failure occurrence detection means for detecting occurrence of a failure in the first transmission path at a future time based on the acquired first variation quality value.
Further, the data transmission means is configured to select the operation transmission path from the first transmission path to the first one of the plurality of transmission paths when it is detected that a failure occurs in the first transmission path. Change to a second transmission path different from the transmission path.
Fifth Embodiment
An optical communication method according to another aspect of the present invention includes a transmitter and a receiver, and is applied to an optical communication system that transmits data from the transmitter to the receiver by an optical signal.
In this optical communication method, 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 transmission is performed via the set operation transmission path. The data is transmitted from the device to the receiving device.
Furthermore, in the optical communication method, the first variation of the value representing the quality of the optical signal received by the receiver via the first transmission path is a time-varying component caused by polarization mode dispersion. Get variable quality value.
Further, the optical communication method detects occurrence of a failure in the first transmission path at a future time based on the acquired first fluctuation quality value.
Furthermore, in the optical communication method, when it is detected that a failure occurs in the first transmission path, the first transmission path among the plurality of transmission paths is transmitted from the first transmission path to the operation transmission path. Change to a second transmission path different from the path.
Sixth Embodiment
The fault detection apparatus according to another embodiment of the present invention receives a light signal and obtains a fluctuation quality value which is a time fluctuation component caused by polarization mode dispersion among values representing the quality of the light signal. Means for acquiring variable quality value.
The fault detection apparatus further includes fault occurrence detection means for detecting occurrence of a fault in the transmission path through which the optical signal is transmitted at a future time based on the acquired fluctuation quality value.
Seventh Embodiment
In a fault detection method according to another aspect of the present invention, an optical signal is input, and among values representing the quality of the optical signal, a fluctuation quality value that is a time fluctuation component caused by polarization mode dispersion is acquired.
Furthermore, the fault detection method detects that a fault occurs in a transmission path through which the optical signal is transmitted at a future time based on the acquired variable quality value.
Eighth Embodiment
A program according to another aspect of the present invention is a program for detecting a fluctuation quality value, which is a time fluctuation component caused by polarization mode dispersion, out of the values representing the quality of the optical signal, It has a variable quality value acquisition means to acquire.
Further, the program realizes failure occurrence detection means for detecting occurrence of a failure in the transmission path through which the optical signal is transmitted at a future time based on the acquired fluctuation quality value.
As mentioned above, although this invention was demonstrated with reference to the said embodiment, this invention is not limited to embodiment mentioned above. Various modifications that can be understood by those skilled in the art within the scope of the present invention can be made to the configuration and details of the present invention.
In 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 may include a processing device and a storage device storing a program (software). Furthermore, the optical communication system may be configured to realize each function by the processing device executing the program. 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.
Further, as another modification of the above-described embodiment, any combination of the above-described embodiment and modification may be adopted.
Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above embodiments. The configurations and details of the present invention can be modified in various ways that can be understood by those skilled in the art within the scope of the present invention.
This application claims priority based on Japanese Patent Application No. 2010-067248, filed March 24, 2010, the entire disclosure of which is incorporated herein.
<Supplementary Note>
Although a part or all of the above-mentioned embodiment may be described like the following supplementary notes, it is not restricted to the following.
(Supplementary Note 1)
An optical communication system for transmitting an optical signal from a transmitter to a receiver via an operation transmission path which is any of a plurality of transmission paths,
Fluctuation quality value acquiring means for acquiring fluctuation quality value which is a time fluctuation component caused by polarization mode dispersion among values representing the quality of the optical signal received by the receiving apparatus through the operation transmission line When,
Failure occurrence detection means for detecting occurrence of a failure in the operation transmission path at a future time based on the first variation quality value, and outputting a failure occurrence warning signal;
An optical communication system comprising data transmission means for changing the operation transmission path to another transmission path when the failure occurrence alarm signal is input.
(Supplementary Note 2)
The optical communication system according to appendix 1, wherein
The variation quality value acquisition means is based on the value of the SOP (State of Polarization) vector locus length which is the length of the locus drawn by the Stokes vector on the Poincare sphere in the wavelength band of the optical signal or the degree of polarization. An optical communication system for acquiring the first variable quality value.
(Supplementary Note 3)
The optical communication system according to Appendix 1 or 2.
The failure occurrence detection means is configured such that a ratio of a total time in which the acquired first variation quality value becomes smaller than a preset quality threshold within a determination period set in advance is relative to the determination period. An optical communication that detects occurrence of a fault in the operation transmission path when the ratio is equal to or greater than a preset percentage threshold and the time change rate of the acquired first variation quality value is a negative value. system.
(Supplementary Note 4)
The optical communication system according to Appendix 1 or 2.
The failure occurrence detection means, when the state in which the time change rate of the acquired first variation quality value is a negative value continues over a time threshold set in advance, the first transmission path Optical communication system that detects that a failure occurs.
(Supplementary Note 5)
The optical communication system according to Appendix 3 or 4.
The optical communication system according to claim 1, wherein the failure occurrence detection unit acquires a time change rate of a value obtained by smoothing the acquired first change quality value as a time change rate of the first change quality value.
(Supplementary Note 6)
The optical communication system according to any one of supplementary notes 1 to 5, wherein
Until the occurrence of a failure in the operation transmission path is detected, the supply of power for transmitting data via another transmission path is stopped, and a failure occurs in the operation transmission path. An optical communication system that starts supply of the power when it is detected.
(Appendix 7)
The optical communication system according to any one of supplementary notes 1 to 5, wherein
The fluctuation quality value acquiring means is a time fluctuation due to polarization mode dispersion among values representing the quality of the optical signal received by the receiving apparatus via a predetermined transmission path other than the operation transmission path. Get the second variation quality value that is the component,
The failure occurrence detection means detects occurrence of a failure in the predetermined transmission path based on the acquired second fluctuation quality value.
The data transmission means detects the occurrence of a failure in the operation transmission path, and does not detect the occurrence of a failure in the predetermined transmission path. Optical communication system to change to a predetermined transmission path.
(Supplementary Note 8)
The optical communication system according to appendix 7, wherein
The supply of power for transmitting data via the predetermined transmission path is stopped until the occurrence of a failure in the operation transmission path is detected,
The optical communication system according to claim 1, wherein the fluctuation quality value acquiring unit acquires the second fluctuation quality value based on noise light received by the receiving apparatus and output from an optical amplifier disposed in the predetermined transmission path. .
(Appendix 9)
It is applied to an optical communication system for transmitting an optical signal from a transmitter to a receiver via an operation transmission path which is any of a plurality of transmission paths,
Acquiring, among the values representing the quality of the optical signal received by the receiving apparatus via the operation transmission line, a fluctuation quality value which is a time fluctuation component caused by polarization mode dispersion;
Based on the first variation quality value, it is detected that a failure occurs in the operation transmission path at a future time, and a failure occurrence warning signal is output,
An optical communication method, wherein the operation transmission path is changed to another transmission path when the failure occurrence warning signal is input.
(Supplementary Note 10)
It is the optical communication method according to appendix 9.
The first variation quality value is determined based on the SOP (State of Polarization) vector locus length, which is the length of the locus drawn by the Stokes vector on the Poincare sphere in the wavelength band of the optical signal, or the degree of polarization. Optical communication method to acquire.
(Supplementary Note 11)
The optical communication method according to Supplementary Note 9 or 10.
The ratio of the total of the times when the acquired first variation quality value becomes smaller than the preset quality threshold within the preset judgment period to the decision period is the preset threshold value This is the optical communication method for detecting occurrence of a failure in the operation transmission path when the above is true and the time change rate of the acquired first variable quality value is a negative value.
(Supplementary Note 12)
The optical communication method according to Supplementary Note 9 or 10.
When a state in which the temporal change rate of the acquired first fluctuation quality value is a negative value continues over a preset time threshold or more, a fault occurs in the first transmission path. Optical communication method to detect
(Supplementary Note 13)
The optical communication method according to Supplementary Note 11 or 12.
The optical communication method, wherein a time change rate of a value obtained by smoothing the acquired first change quality value is obtained as a time change rate of the first change quality value.
(Supplementary Note 14)
The optical communication method according to any one of Appendixes 9 to 13,
Until the occurrence of a failure in the operation transmission path is detected, the supply of power for transmitting data via another transmission path is stopped, and a failure occurs in the operation transmission path. An optical communication method, which starts the supply of the power when it is detected.
(Supplementary Note 15)
The optical communication method according to any one of Appendixes 9 to 13,
A second fluctuation quality, which is a time-varying component due to polarization mode dispersion, among values representing the quality of the optical signal received by the receiving apparatus via a predetermined transmission path other than the operation transmission path Get the value,
Based on the acquired second fluctuation quality value, it is detected that a failure occurs in the predetermined transmission path,
When it is detected that a failure occurs in the operation transmission path, and it is not detected that a failure occurs in the predetermined transmission path, the operation transmission path is changed to the predetermined transmission path. The optical communication method.
(Supplementary Note 16)
The optical communication method according to appendix 15, wherein
The transmission device is configured to stop supplying power for transmitting data via the predetermined transmission path until occurrence of a failure in the operation transmission path is detected;
The optical communication according to claim 1, wherein the fluctuation quality value acquiring unit acquires the second fluctuation quality value based on noise light received by the receiving apparatus and output from an optical amplifier disposed in the predetermined transmission path. Method.
(Supplementary Note 17)
Fluctuation quality value acquiring means for acquiring a fluctuation quality value which is a time fluctuation component caused by polarization mode dispersion among the values representing the quality of the optical signal while being inputted with an optical signal,
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 based on the acquired fluctuation quality value;
Fault detection device provided with
(Appendix 18)
The fault detection apparatus according to appendix 17, wherein
The variation quality value acquisition means is based on the value of the SOP (State of Polarization) vector locus length which is the length of the locus drawn by the Stokes vector on the Poincare sphere in the wavelength band of the optical signal or the degree of polarization. A fault detection device for acquiring the first variable quality value;
(Appendix 19)
The fault detection device according to Supplementary Note 17 or 18.
The failure occurrence detection means is configured such that a ratio of a total time in which the acquired first variation quality value becomes smaller than a preset quality threshold within a determination period set in advance is relative to the determination period. Failure detection that detects occurrence of a failure in the operation transmission path if the ratio is equal to or higher than a preset ratio threshold and the time change rate of the acquired first fluctuation quality value is a negative value apparatus.
(Supplementary Note 20)
The fault detection device according to Supplementary Note 17 or 18.
The failure occurrence detection means, when the state in which the time change rate of the acquired first variation quality value is a negative value continues over a time threshold set in advance, the first transmission path Failure detection device that detects that a failure occurs in
(Supplementary Note 21)
An optical signal is input, and among the values representing the quality of the optical signal, a fluctuation quality value that is a time fluctuation component caused by polarization mode dispersion is acquired,
Based on the acquired fluctuation quality value, it is detected in the future that a failure will occur in a transmission path through which the optical signal is transmitted,
Failure detection method
(Supplementary Note 22)
The fault detection method according to appendix 21
The first variation quality value is determined based on the SOP (State of Polarization) vector locus length, which is the length of the locus drawn by the Stokes vector on the Poincare sphere in the wavelength band of the optical signal, or the degree of polarization. Failure detection method to acquire.
(Supplementary Note 23)
The fault detection method according to Supplementary Note 21 or 22.
The ratio of the total of the times when the acquired first variation quality value becomes smaller than the preset quality threshold within the preset judgment period to the decision period is the preset threshold value This is the failure detection method for detecting that a failure occurs in the operation transmission path when the time change rate of the acquired first variation quality value is negative, as described above.
(Supplementary Note 24)
The fault detection method according to Supplementary Note 21 or 22.
When a state in which the temporal change rate of the acquired first fluctuation quality value is a negative value continues over a preset time threshold or more, a fault occurs in the first transmission path. Failure detection method to detect
(Appendix 25)
Fluctuation quality value acquisition means for acquiring a fluctuation quality value which is a time fluctuation component caused by polarization mode dispersion among values representing the quality of the optical signal, in the fault detection apparatus to which the optical signal is inputted;
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 based on the acquired fluctuation quality value;
Fault detection program to realize the
(Appendix 26)
It is a program described in Appendix 25 and
The variation quality value acquisition means is based on the value of the SOP (State of Polarization) vector locus length which is the length of the locus drawn by the Stokes vector on the Poincare sphere in the wavelength band of the optical signal or the degree of polarization. An obstacle detection program for acquiring the first fluctuation quality value.
(Appendix 27)
26. The failure detection program according to Supplementary Note 25 or 26.
The failure occurrence detection means is configured such that a ratio of a total time in which the acquired first variation quality value becomes smaller than a preset quality threshold within a determination period set in advance is relative to the determination period. Failure detection that detects occurrence of a failure in the operation transmission path if the ratio is equal to or higher than a preset ratio threshold and the time change rate of the acquired first fluctuation quality value is a negative value program.
(Appendix 28)
26. The failure detection program according to Supplementary Note 25 or 26.
The failure occurrence detection means, when the state in which the time change rate of the acquired first variation quality value is a negative value continues over a time threshold set in advance, the first transmission path Failure detection program that detects that a failure occurs in

The present invention is applicable to an optical communication system or the like that transmits data by means of an optical signal from a transmitter to a receiver, and has industrial applicability.

1000 Optical communication systems 1001, 1002, 1003 Node devices 1004, 1005, 1006 Optical fibers 1007, 1008, 1009 Optical amplifiers 1010, 1011 Optical splitters 1012, 1013 Optical signal quality monitor 1015 Polarizers 4001, 4002 Optical transmitters 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 splitter 5012, 5013 Optical signal quality monitor 5015 Polarizer 5017, 5018 Wavelength multiplexer 5019, 5020 Wavelength separator 5021 to 5028 Optical receiver 5031 to 5038 Optical transmitter 7000 Optical communication system 7001 Data transmission unit 7002 Fluctuation quality Acquisition unit 7003 failure detection unit

Claims (10)

1. An optical communication system for transmitting an optical signal from a transmitter to a receiver via an operation transmission path which is any of a plurality of transmission paths,
   Fluctuation quality for acquiring a first fluctuation quality value which is a time fluctuation component caused by polarization mode dispersion among values representing the quality of the optical signal received by the receiving apparatus through the operation transmission line Value acquisition means,
   Failure occurrence detection means for detecting occurrence of a failure in the operation transmission path at a future time based on the first variation quality value, and outputting a failure occurrence warning signal;
   An optical communication system comprising data transmission means for changing the operation transmission path to another transmission path when the failure occurrence alarm signal is input.
2. The optical communication system according to claim 1,
   The variation quality value acquiring means is based on the value of the SOP (State of Polarization) vector locus length or the degree of polarization, which is the length of the locus drawn by the Stokes vector on the Poincare sphere in the wavelength band of the optical signal. An optical communication system for acquiring the first variable quality value.
3. The optical communication system according to claim 1 or 2,
   The failure occurrence detection means is configured such that a ratio of a total time in which the acquired first variation quality value becomes smaller than a preset quality threshold within a determination period set in advance is relative to the determination period. An optical communication that detects occurrence of a fault in the operation transmission path when the ratio is equal to or greater than a preset percentage threshold and the time change rate of the acquired first variation quality value is a negative value. system.
4. The optical communication system according to claim 1 or 2,
   The failure occurrence detection means, when the state in which the time change rate of the acquired first variation quality value is a negative value continues over a time threshold set in advance, the first transmission path Optical communication system that detects that a failure occurs.
5. An optical communication system according to claim 3 or claim 4, wherein
   The optical communication system according to claim 1, wherein the failure occurrence detection unit acquires a time change rate of a value obtained by smoothing the acquired first change quality value as a time change rate of the first change quality value.
6. The optical communication system according to any one of claims 1 to 5, wherein
   Until the occurrence of a failure in the operation transmission path is detected, the supply of power for transmitting data via another transmission path is stopped, and a failure occurs in the operation transmission path. An optical communication system that starts supply of the power when it is detected.
7. The optical communication system according to any one of claims 1 to 5, wherein
   The fluctuation quality value acquiring means is a time fluctuation due to polarization mode dispersion among values representing the quality of the optical signal received by the receiving apparatus via a predetermined transmission path other than the operation transmission path. Get the second variation quality value that is the component,
   The failure occurrence detection means detects occurrence of a failure in the predetermined transmission path based on the acquired second fluctuation quality value.
   The data transmission means detects the occurrence of a failure in the operation transmission path, and does not detect the occurrence of a failure in the predetermined transmission path. Optical communication system to change to a predetermined transmission path.
8. The optical communication system according to claim 7, wherein
   The supply of power for transmitting data via the predetermined transmission path is stopped until the occurrence of a failure in the operation transmission path is detected,
   The optical communication system according to claim 1, wherein the fluctuation quality value acquiring unit acquires the second fluctuation quality value based on noise light received by the receiving apparatus and output from an optical amplifier disposed in the predetermined transmission path. .
9. It is applied to an optical communication system for transmitting an optical signal from a transmitter to a receiver via an operation transmission path which is any of a plurality of transmission paths,
   Acquiring a first fluctuation quality value, which is a time fluctuation component caused by polarization mode dispersion, among values representing the quality of the optical signal received by the receiving apparatus through the operation transmission line;
   Based on the first variation quality value, it is detected that a failure occurs in the operation transmission path at a future time, and a failure occurrence warning signal is output,
   An optical communication method, wherein the operation transmission path is changed to another transmission path when the failure occurrence warning signal is input.
10. Fluctuation quality value acquiring means for acquiring a fluctuation quality value which is a time fluctuation component caused by polarization mode dispersion among the values representing the quality of the optical signal while being inputted with an optical signal,
    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 based on the acquired fluctuation quality value;
    Fault detection device comprising:

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