Optical transport control device, optical transport device, and optical transport control method

Abstract

One aspect of the present invention is an optical transport system for transporting analog optical signals, the optical transport system having: an optical transmission device that converts electrical signals into optical signals and outputs the optical signals; a plurality of optical transport devices that transport the optical signals; and an optical reception device that converts the optical signals into electrical signals and outputs the electrical signals. The optical transport system is an optical transport control device comprising: a monitoring unit that monitors a decrease in the power of the optical input signals inputted to the optical transport devices; and a setting unit for setting, for each of the plurality of optical transport devices, a power threshold for detecting the decrease in the power of the optical input signals.

Description

Optical transmission control device, optical transmission device, and optical transmission control method

[0001] The present invention relates to optical transmission control devices, optical transmission devices, and optical transmission control methods.

[0002] In systems that transmit optical signals, standards have been established for transmitting optical signals as analog signals (see, for example, Non-Patent Documents 1 and 2).

[0003] The transmission system described in Non-Patent Documents 1 and 2 comprises an optical transmitter, an optical transmission device, an optical receiver, and a monitoring and control device. The optical transmitter primarily has the functions of amplifying the input signal and converting electrical signals to optical signals, and may also have optical signal amplification functions, various control functions, and, in Non-Patent Document 1, a conversion function that converts the input signal to an FM (frequency modulation) signal. The optical transmission device primarily has the function of amplifying optical signals, and may also have optical signal processing functions such as dispersion compensation and optical signal distribution functions. The optical receiver has the function of converting optical signals to electrical signals, and may also have electrical signal amplification functions, and, in Non-Patent Document 1, an FM signal demodulation function. These devices are monitored for fault conditions and controlled by the monitoring and control device. The devices and the monitoring and control device are connected via a communication network such as IP / Ethernet. In optical transmission and optical receiver devices that have a mechanism to detect and notify of a decrease in the power level of the optical input signal, an alarm is issued when the input power falls below an input power decrease detection threshold held by the device.

[0004] “Transmission equipment for transferring multi-channel television signals over optical access networks by frequency modulation conversion” ITU-T Rec. J. 185, 2012 “Transmission equipment for multi-channel television signals over optical access networks by sub-carrier multiplexing (SCM)” ITU-T Rec. J. 186, 2008

[0005] However, in conventional technology, the transmission distance between optical transmission devices varies, and the allowable transmission loss is large when the distance is short, while conversely, the allowable loss is small when the distance is long. Therefore, conventional technology has the problem that it cannot be said that appropriate anomaly detection is performed according to the transmission distance. In view of the above circumstances, the present invention aims to provide a technology for appropriately detecting signal power anomalies in a transmission system according to the transmission distance.

[0006] One aspect of the present invention is an optical transmission system for transmitting analog optical signals, comprising: an optical transmitting device that converts an electrical signal into an optical signal and outputs it; a plurality of optical transmission devices that transmit the optical signal; and an optical receiving device that converts the optical signal into an electrical signal and outputs it, wherein the optical transmission control device comprises: a monitoring unit that monitors a decrease in the power of an optical input signal input to the optical transmission device; and a setting unit that sets a power threshold for detecting a decrease in the power of the optical input signal for each of the plurality of optical transmission devices.

[0007] One aspect of the present invention is an optical transmission system for transmitting analog optical signals, comprising: an optical transmitting device that converts an electrical signal into an optical signal and outputs it; a plurality of optical transmission devices that transmit the optical signal; and an optical receiving device that converts the optical signal into an electrical signal and outputs it, wherein the optical transmission device comprises: a monitoring unit that monitors a decrease in the power of an optical input signal input to the optical transmission device; and a setting unit that sets a power threshold for detecting a decrease in the power of the optical input signal for each of the plurality of optical transmission devices.

[0008] One aspect of the present invention is an optical transmission system for transmitting analog optical signals, comprising an optical transmitting device that converts an electrical signal into an optical signal and outputs it, a plurality of optical transmission devices that transmit the optical signal, and an optical receiving device that converts the optical signal into an electrical signal and outputs it, wherein a monitoring unit monitors the decrease in the power of the optical input signal input to the optical transmission device, and a setting unit sets a power threshold for detecting the decrease in the power of the optical input signal for each of the plurality of optical transmission devices, and is an optical transmission control method.

[0009] This invention makes it possible to appropriately detect signal power anomalies in a transmission system according to the transmission distance.

[0010] This is a diagram showing an example configuration of an optical transmission system according to the embodiment. This is a diagram showing an example configuration of an optical transmission device according to the embodiment. This is a diagram showing an example configuration of an optical transmission device when the optical transmission device is equipped with the functions of a monitoring and control device. This is a diagram showing an example configuration of an optical transmission system in which one optical transmission device is equipped with a monitoring and control device. This is a diagram showing an example configuration of an optical receiver according to the embodiment. This is a diagram showing an example configuration of an optical transmission device when the optical receiver is equipped with the functions of a monitoring and control device. This is a diagram showing a schematic of the hardware configuration example of some functions of the optical transmitter, some functions of the optical transmission device, some functions of the optical receiver, and some functions of the monitoring and control device applied to the embodiment. This is a diagram for explaining an example of operation of the optical transmission system according to the embodiment. This is a flowchart of the processing procedure of the first example. This is a flowchart of the processing procedure of the second example.

[0011] Embodiments of the present invention will be described in detail with reference to the drawings. Figure 1 is a diagram showing an example configuration of the optical transmission system of this embodiment. As shown in Figure 1, the optical transmission system 1 includes, for example, an optical transmitting device 2, optical transmission devices 3 (3-1, ..., 3-n (where n is an integer of 2 or more)), an optical receiving device 4, and a monitoring and control device 5 (optical transmission control device). The monitoring and control device 5 includes, for example, a monitoring unit 52, a setting unit 53, a notification unit 54, and a storage unit 55.

[0012] The optical transmitter 2 receives an input signal (y1), which is an electrical signal, for example, using the FDM (Frequency Division Multiplexing) method, from another device. The optical transmitter 2 converts the input electrical signal into an optical signal and outputs the converted optical signal (y11) to the optical transmission device 3. The optical transmitter 2 outputs information indicating the power of the output optical signal (hereinafter, "output optical signal" is also referred to as "output optical signal") as a monitoring control signal to the monitoring control device 5. The optical transmitter 2 and the optical transmission device 3 are connected to each other by an optical fiber cable (transmission path). The optical transmitter 2 and the monitoring control device 5 are connected to each other via a network NW, such as a communication network. The optical transmitter 2 and the monitoring control device 5 transmit and receive monitoring control signals (y21) via the network NW.

[0013] The optical transmission device 3 receives an optical signal (y11) from the preceding optical transmission device 2 or optical transmission device 3. The optical transmission device 3 and other optical transmission devices 3 are connected to each other by optical fiber cables. The optical transmission device 3 and optical receiving device 4 are also connected to each other by optical fiber cables. The optical transmission device 3 amplifies the input optical signal and outputs the optical signal (y11) to the subsequent optical transmission device 3 or optical receiving device 4. The optical transmission device 3 also outputs the optical signal (y11) to another optical transmission device 3 or optical receiving device 4. For example, during normal operation at the start of communication, the optical transmission device 3 measures the power of the input optical signal (hereinafter, "input optical signal" is also referred to as "input optical signal") and outputs at least one of the information indicating the power of the measured optical input signal and information indicating the power of the optical output signal as a monitoring control signal to the monitoring control device 5. The optical transmission device 3 stores the threshold value output by the monitoring control device 5 in a memory unit provided in the optical transmission device 3. The optical transmission device 3 measures the power of the optical input signal at predetermined time intervals, for example, and compares the measured value with a threshold value. If, as a result of the comparison, the optical transmission device 3 finds that the power of the optical input signal is below the threshold value, the optical transmission device 3 outputs an abnormality detection result to the monitoring control device 5. The optical transmission device 3 and the monitoring control device 5 are connected to each other via a network NW such as a communication network. The optical transmission device 3 and the monitoring control device 5 transmit and receive monitoring control signals (y21) via the network NW.

[0014] The optical receiver 4 receives an optical signal (y11) from the preceding optical transmission device 3. The optical receiver 4 measures the power of the optical input signal, for example, during normal operation at the start of communication, and outputs information indicating the measured power of the optical input signal as a monitoring control signal to the monitoring control device 5. The optical receiver 4 stores the threshold value output by the monitoring control device 5 in a memory unit provided in the optical receiver 4. The optical receiver 4 measures the power of the optical input signal, for example, at predetermined time intervals, and compares the measured value with the threshold value. If, as a result of the comparison, the power of the optical input signal falls below the threshold value, the optical receiver 4 outputs an abnormality detection result to the monitoring control device 5.

[0015] The monitoring and control device 5 calculates an input power reduction detection threshold (hereinafter, "input power reduction detection threshold" is also referred to as "threshold") for each of the optical transmission devices 3, using, for example, the power of the normal optical output signal at the start of communication input from the optical transmission device 2, at least one of, for example, the power of the normal optical input signal and the power of the optical output signal at the start of communication input from the optical transmission device 3, and for example, the normal optical input signal power at the start of communication input from the optical receiver device 4. The monitoring and control device 5 stores the calculated thresholds in a memory unit provided in the monitoring and control device 5. The monitoring and control device 5 also stores identification information that identifies the device corresponding to the threshold. The monitoring and control device 5 may calculate the threshold based on the attenuation of the optical fiber if the distance of the transmission path section is known. The monitoring and control device 5 may also set the threshold when only one optical receiver is connected under the optical transmission device 3. Alternatively, the monitoring and control device 5 may set the threshold based on the optical transmission device 3. In this way, the monitoring and control device 5 may set conditions or rules for setting the threshold. The monitoring and control device 5 outputs the threshold value as a monitoring and control signal to the optical transmitter 2 and the optical transmission device 3, respectively.

[0016] The monitoring unit 52 acquires information indicating the power of the optical output signal from the optical transmitter 2 and the optical transmission device 3, or information indicating the power of the optical input signal from the optical transmission device 3 and the optical receiver 4, or all of these. The monitoring unit 52 uses the acquired information and parameters stored in the storage unit 55 (such as information regarding the transmission section) to monitor for any decrease in the power of the incoming optical input signal.

[0017] The setting unit 53 sets a power threshold for each optical transmission device 3 to detect a decrease in the power of the incoming optical input signal. The method for calculating the threshold, parameters, etc., will be described later.

[0018] The notification unit 54 notifies the threshold corresponding to each of the optical transmission devices 3.

[0019] The memory unit 55 stores the threshold values ​​for each of the optical transmission devices 3, parameters described later, etc. The memory unit 55 stores identification information that can identify the optical transmission devices 3 and associates the threshold values ​​corresponding to each optical transmission device 3.

[0020] In addition to providing information via a communication network, the monitoring and control device 5 may also use a portion of the main signal transmission area, such as AMCC (Auxiliary Management and Control Channel). In this case, the monitoring and control function will be built into one of the devices.

[0021] (Example of optical transmission device configuration) Figure 2 is a diagram showing an example of the configuration of the optical transmission device according to this embodiment. As shown in Figure 2, the optical transmission device 3 includes, for example, an optical signal processing unit 31, an optical amplification unit 32, an optical signal distribution unit 33, a notification unit 34, and a storage unit 35.

[0022] The optical signal processing unit 31 outputs the input optical signal to the optical amplification unit 32. The optical signal processing unit 31 measures the power of the input optical signal at the start of communication and at predetermined time intervals. For example, at the start of communication, the optical signal processing unit 31 outputs information indicating the measured power of the optical input signal at the start of communication to the notification unit 34. The optical signal processing unit 31 compares the power of the optical input signal measured at predetermined time intervals with a threshold value stored in the storage unit 35 to determine whether the power of the optical input signal is less than the threshold value. If the power of the optical input signal is less than the threshold value, the optical signal processing unit 31 outputs the abnormality detection result to the notification unit 34.

[0023] The optical amplification unit 32 amplifies the optical signal output by the optical signal processing unit 31, for example, by a predetermined amplification factor. The optical amplification unit 32 outputs the amplified optical signal to the optical signal distribution unit 33. For example, the optical amplification unit 32 may measure the power of the optical input signal at the start of communication or at predetermined time intervals. In this case, the optical amplification unit 32 notifies the notification unit 34 of information indicating the measured power of the optical input signal.

[0024] The optical signal distribution unit 33 distributes and outputs the optical signal amplified by the optical amplification unit 32 to the devices connected to the optical transmission device 3. The optical signal distribution unit 33 measures the power of the output optical signal at the start of communication and outputs information indicating the measured optical output power to the notification unit 34.

[0025] The notification unit 34 outputs at least one of the following to the monitoring and control device 5: information indicating the power of the optical input signal at the start of communication and information indicating the optical output power. The notification unit 34 obtains a threshold value from the monitoring and control device 5. The notification unit 34 outputs the abnormality detection result to the monitoring and control device 5.

[0026] The memory unit 35 stores threshold values ​​obtained from the monitoring and control device 5. The memory unit 35 also stores the amplification ratio of the optical amplification unit 32.

[0027] (Other Configuration Examples of Optical Transmission Devices) Next, we will describe an example in which at least one of the optical transmission devices has the function of a monitoring and control device (optical transmission control device). Figure 3 is a diagram showing an example of the configuration of an optical transmission device when the optical transmission device has the function of a monitoring and control device. As shown in Figure 3, the optical transmission device 3A includes, for example, an optical signal processing unit 31A, an optical amplification unit 32, an optical signal distribution unit 33A, a monitoring and control device 36 (optical transmission control device), and a storage unit 35. The monitoring and control device 36 includes, for example, a monitoring unit 362, a setting unit 363, a notification unit 364, and a storage unit 365.

[0028] The optical signal processing unit 31A outputs the input optical signal to the optical amplification unit 32. The optical signal processing unit 31A measures the power of the input optical signal at the start of communication and at predetermined time intervals. For example, at the start of communication, the optical signal processing unit 31A stores information indicating the power of the optical input signal at the start of communication in the storage unit 35. For example, the optical signal processing unit 31A stores in the storage unit 35A at least one of the information indicating the power of the optical input signal and the optical output signal of another optical transmission device 3 measured at the start of communication, as well as information indicating the optical output signal power of the optical transmission device 2 at the start of communication and information indicating the power of the optical input signal of the optical receiving device 4 at the start of communication, and outputs these to the monitoring and control device 36. The optical signal processing unit 31A compares the power of the optical input signal measured at predetermined time intervals with a threshold value stored in the storage unit 35A to determine whether the power of the optical input signal is less than the threshold value. If the power of the optical input signal is less than the threshold value, the optical signal processing unit 31A outputs an abnormality detection result to the monitoring and control device 36.

[0029] The optical amplification unit 32 amplifies the optical signal output by the optical signal processing unit 31A, for example, by a predetermined amplification factor. The optical amplification unit 32 outputs the amplified optical signal to the optical signal distribution unit 33A. For example, the optical amplification unit 32 may measure the power of the optical input signal at the start of communication or at predetermined time intervals. In this case, the optical amplification unit 32 notifies the monitoring and control device 36 of information indicating the measured power of the optical input signal.

[0030] The optical signal distribution unit 33A distributes and outputs the optical signal amplified by the optical amplification unit 32 to the devices connected to the optical transmission device 3A. The optical signal distribution unit 33A measures the power of the output optical signal at the start of communication, stores the information indicating the measured optical output power in the storage unit 35A, and outputs it to the monitoring and control device 36.

[0031] The storage unit 35A stores, for example, information indicating the power of the optical output signal of the optical transmitter 2 at the start of communication; at least one of the information indicating the power of the optical input signal and the optical output signal of the optical transmission device 3A at the start of communication; at least one of the information indicating the power of the optical input signal and the optical output signal of the optical transmission device 3 at the start of communication; and information indicating the power of the optical output signal of the optical receiver 4 at the start of communication. The storage unit 35A stores threshold values ​​output by the monitoring and control device 36. The storage unit 35A stores the amplification ratio of the optical amplifier 32.

[0032] The monitoring and control device 36 acquires, for example, information indicating the power of the optical output signal of the optical transmitter 2 at the start of communication, at least one of the information indicating the power of the optical input signal and the optical output signal of the optical transmission device 3 at the start of communication, and information indicating the power of the optical output signal of the optical receiver 4 at the start of communication, via the network NW. The monitoring and control device 36 uses at least one of the information indicating the power of the optical input signal and the optical output signal of the optical transmission device 3 at the start of communication, along with the acquired information, to calculate threshold values ​​for optical transmission device 3A and optical transmission device 3, respectively. The monitoring and control device 36 stores the calculated threshold values ​​in the storage unit 35A. The monitoring and control device 36 outputs the calculated threshold values ​​to each of the optical transmission devices 3 via the network NW. If an abnormality is detected, the monitoring and control device 36 notifies, for example, an external device used by the administrator of the optical transmission system 1. In this way, the monitoring and control device 36 has a mechanism to monitor a decrease in the power of the input optical signal and a function to set a power threshold for detecting a decrease in the power of the input optical signal for each of the multiple optical transmission devices.

[0033] The monitoring unit 362 acquires information indicating the power of the optical output signal from the optical transmitter 2, the optical transmission device 3, and the optical transmission device 3A of its own device, or information indicating the power of the optical input signal from the optical transmission device 3, the optical transmission device 3A of its own device, and the optical receiver 4, or any of these. The monitoring unit 362 uses the acquired information and parameters stored in the storage unit 365 (such as information regarding the transmission section) to monitor the decrease in the power of the incoming optical input signal.

[0034] The setting unit 363 sets a power threshold for detecting a decrease in the power of the incoming optical input signal for each of its own optical transmission devices 3A and 3.

[0035] The notification unit 364 notifies the threshold values ​​corresponding to the optical transmission device 3A and optical transmission device 3 of its own device, respectively.

[0036] The storage unit 365 stores the threshold values ​​for the optical transmission device 3A and optical transmission device 3 of the device, as well as parameters described later. The storage unit 365 stores identification information that can identify the optical transmission device 3A and optical transmission device 3 of the device, and associates the threshold values ​​corresponding to the optical transmission device 3A and each optical transmission device 3 of the device. The information stored by the storage unit 365 may be stored by the storage unit 35A, and the information stored by the storage unit 35A may be stored by the storage unit 365.

[0037] Figure 4 shows an example of the configuration of an optical transmission system in which one optical transmission device is equipped with a monitoring and control device. In the example in Figure 4, the optical transmission device 3A-1 connected downstream of the optical transmitter 2 is equipped with a monitoring and control device 36 (optical transmission control device). In such a configuration, the optical transmission device 3A-1 equipped with the monitoring and control device 36 acquires, for example, information indicating the power of the optical output signal of the optical transmitter 2 at the start of communication, at least one of the information indicating the power of the optical input signal and the optical output signal of the other optical transmission device 3 at the start of communication, and information indicating the power of the optical output signal of the optical receiver 4 at the start of communication, via the network NW. The optical transmission device 3A-1 uses at least one of the information indicating the power of the optical input signal and the optical output signal of the other optical transmission device 3 at the start of communication, along with the acquired information, to calculate thresholds for optical transmission device 3A and optical transmission device 3, respectively. The optical transmission device 3A-1 then outputs the calculated thresholds to each of the optical transmission devices 3 via the network NW. If an abnormality is detected, the optical transmission device 3A-1 notifies an external device used by, for example, the administrator of the optical transmission system 1.

[0038] Note that the configuration examples and operations shown using Figures 2 to 4 are examples only and are not limited thereto. For example, the monitoring and control device 36 (optical transmission control device) may be provided by all optical transmission devices. In this case, at least one of the multiple optical transmission devices 3A equipped with the monitoring and control device 36 may calculate a threshold and notify the other optical transmission devices 3A.

[0039] (Configuration Example of Optical Receiver) Fig. 5 is a diagram showing a configuration example of the optical receiver of the present embodiment. As shown in Fig. 5, the optical receiver 4 includes, for example, a conversion unit 41, a demodulation unit 42, an amplification unit 43, a notification unit 44, and a storage unit 45.

[0040] The conversion unit 41 acquires the optical signal output by the optical transmission device 3, measures the power of the acquired optical signal at, for example, the start of communication and at predetermined time intervals, and outputs information indicating the power of the measured optical input signal to the notification unit 44. The conversion unit 41 converts the acquired optical signal into an electrical signal and outputs the converted electrical signal to the demodulation unit 42. The conversion unit 41 compares the power of the optical input signal measured at predetermined time intervals with the threshold value stored in the storage unit 45 to determine whether the power of the optical input signal is less than the threshold value. When the power of the optical input signal is less than the threshold value, the conversion unit 41 outputs an abnormality detection result to the notification unit 44.

[0041] The demodulation unit 42 performs, for example, FM (frequency modulation) signal demodulation processing on the electrical signal output by the conversion unit 41. The demodulation unit 42 outputs the demodulated signal to the amplification unit 43. When the conversion unit 41 and the demodulation unit 42 are integrated, the abnormality detection result notified from the conversion unit 41 to the notification unit 44 may be notified from the demodulation unit 42 to the notification unit 44.

[0042] The amplification unit 43 performs amplification processing on the electrical signal demodulated by the demodulation unit 42 at a predetermined amplification rate. The amplification unit 43 outputs the amplified FDM output signal to an external device.

[0043] The notification unit 44 outputs information indicating the power of the optical input signal to the monitoring control device 5. The notification unit 44 acquires the threshold value from the monitoring control device 5. The notification unit 44 outputs the abnormality detection result to the monitoring control device 5.

[0044] The storage unit 45 stores the threshold value acquired from the monitoring control device 5. The storage unit 45 stores the amplification rate of the amplification unit 43.

[0045] (Other Configuration Examples of Optical Receiving Devices) Next, we will describe an example in which the optical receiving device is equipped with the functions of a monitoring and control device (optical transmission control device). Figure 6 is a diagram showing an example of the configuration of an optical transmission device when the optical receiving device is equipped with the functions of a monitoring and control device. As shown in Figure 6, the optical receiving device 4A includes, for example, a conversion unit 41A, a demodulation unit 42, an amplification unit 43, a monitoring and control device 46 (optical transmission control device), and a storage unit 45A. The monitoring and control device 46 includes, for example, a monitoring unit 462, a setting unit 463, a notification unit 464, and a storage unit 465.

[0046] The conversion unit 41 acquires the optical signal output by the optical transmission device 3, measures the power of the acquired optical signal, for example at the start of communication and at predetermined time intervals, and outputs information indicating the measured power of the optical input signal to the monitoring and control device 46. The conversion unit 41 converts the acquired optical signal into an electrical signal and outputs the converted electrical signal to the demodulation unit 42. The conversion unit 41 compares the power of the optical input signal measured at predetermined time intervals with a threshold value stored in the storage unit 45 and determines whether the power of the optical input signal is less than the threshold value. If the power of the optical input signal is less than the threshold value, the conversion unit 41 outputs an abnormality detection result to the monitoring and control device 46.

[0047] The demodulation unit 42 performs, for example, FM signal demodulation processing on the electrical signal output by the conversion unit 41. The demodulation unit 42 outputs the demodulated signal to the amplification unit 43.

[0048] The amplification unit 43 performs amplification processing on the electrical signal demodulated by the demodulation unit 42 at a predetermined amplification factor. The amplification unit 43 outputs the amplified FDM output signal to an external device.

[0049] The storage unit 45A stores, for example, information indicating the power of the optical output signal of the optical transmitter 2 at the start of communication, at least one of the information indicating the power of the optical input signal and the optical output signal of the optical transmission device 3 at the start of communication, and for example, information indicating the power of the optical output signal of the optical receiver 4A at the start of communication. The storage unit 45A stores threshold values ​​acquired from the monitoring and control device 5. The storage unit 45A stores the amplification factor of the amplification unit 43.

[0050] The monitoring and control device 46 acquires, for example, information indicating the power of the optical output signal of the optical transmitter 2 at the start of communication, and at least one of the information indicating the power of the optical input signal and the optical output signal of the optical transmission device 3 at the start of communication, via the network NW. The monitoring and control device 36 uses, for example, the information indicating the power of the optical output signal of the optical receiver 4A at the start of communication and the acquired information to calculate a threshold for each of the optical transmission devices 3. The monitoring and control device 46 stores the calculated thresholds in the storage unit 45A. The monitoring and control device 46 outputs the calculated thresholds to each of the optical transmission devices 3 via the network NW. If an abnormality is detected, the monitoring and control device 46 notifies, for example, an external device used by the administrator of the optical transmission system 1. In this way, the monitoring and control device 46 has a mechanism to monitor a decrease in the power of the input optical signal and a function to set a power threshold for detecting a decrease in the power of the input optical signal for each of the multiple optical transmission devices.

[0051] The monitoring unit 462 acquires information indicating the power of the optical output signal from the optical transmitter 2 and the optical transmission device 3, or information indicating the power of the optical input signal from the optical transmission device 3 and the optical receiver 4, or all of these. The monitoring unit 462 uses the information acquired by the acquisition unit 461 and parameters stored in the storage unit 465 (such as information regarding the transmission section) to monitor the decrease in the power of the incoming optical input signal.

[0052] The setting unit 463 sets a power threshold for each optical transmission device 3 to detect a decrease in the power of the incoming optical input signal.

[0053] The notification unit 464 notifies the threshold corresponding to each of the optical transmission devices 3.

[0054] The memory unit 465 stores the threshold values ​​for each of the optical transmission devices 3, parameters described later, etc. The memory unit 465 stores identification information that can identify the optical transmission device 3 and associates the threshold values ​​corresponding to each optical transmission device 3. The information stored by the memory unit 465 may be stored by the memory unit 45A, and the information stored by the memory unit 45A may be stored by the memory unit 465.

[0055] Furthermore, some functions of the optical transmitter 2, some functions of the optical transmission device 3 (or 3A), some functions of the optical receiver 4, and some functions of the monitoring and control device 5 are configured using a processor such as a CPU (Central Processing Unit) and memory. For example, the processor executes a program to function as a function that handles the electrical signals of the optical transmitter. For example, the processor executes a program to function as the notification unit 34 and the monitoring and control device 36 of the optical transmission device (or 3A). For example, the processor executes a program to function as the notification unit 34 and the monitoring and control device 36 of the optical transmission device (or 3A). For example, the processor executes a program to function as some functions of the monitoring and control device 5. Furthermore, all or part of the functions of the optical transmitter 2, the notification unit 34 and the monitoring and control device 36 of the optical transmission device 3 (or 3A), the notification unit 44 and the monitoring and control device 46 of the optical receiver 4 (or 4A), and the monitoring and control device 5 may be implemented using hardware such as an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array). The above program may be recorded on a computer-readable recording medium. Computer-readable recording media include, for example, portable media such as flexible disks, magneto-optical disks, ROMs, CD-ROMs, and semiconductor memory devices (e.g., SSDs: Solid State Drives), as well as storage devices such as hard disks and semiconductor memory devices built into computer systems. The above program may also be transmitted via telecommunications lines.

[0056] Figure 7 is a schematic diagram showing an example of the hardware configuration of some functions of an optical transmitter, some functions of an optical transmission device, some functions of an optical receiver, and some functions of a monitoring and control device applied to this embodiment. As shown in Figure 7, the information processing device 6 includes, for example, a processor 601, a main memory 602, a communication interface 603, an auxiliary storage device 604, an input / output interface 605, and an internal bus 606. The processor 601, the main memory 602, the communication interface 603, the auxiliary storage device 604, and the input / output interface 605 are connected to each other via the internal bus 606 so as to be able to communicate with each other. The information processing device 6 may be applied to some functions of an optical transmitter, some functions of an optical transmission device, some functions of an optical receiver, and some functions of a monitoring and control device. For example, the function of the conversion unit 41 that handles electrical signals may be configured using the communication interface 603 or the input / output interface 605. For example, the monitoring and control device 36, monitoring and control device 46, monitoring and control device 5, demodulation unit 42, and amplification unit 43 may be configured using the processor 601, the main memory 602, and the auxiliary storage device 604. Furthermore, for example, the storage unit 35 (or 35A) and the storage unit 45 (or 45A) may be configured using a main memory device 602 and an auxiliary storage device 604.

[0057] (Example) Figure 8 is a diagram illustrating an example of the operation of the optical transmission system according to this embodiment. First, the parameters in Figure 8 will be explained. The power of the optical output signals of optical transmitter 2 and optical transmission devices 3 (3-1 to 3-n) is set to Pot(k) [dBm]. Note that k is the order as viewed from optical transmission device 3-1. The output power k of optical transmitter 2 is set to 1, and the output power k of the optical transmission device before optical transmission device 3 is set to N. Also, the power of the optical input signal of optical transmission device 3 is set to Pin(k) [dBm]. In this case, the input power k of optical transmission device 3 connected to optical transmitter 2 is set to 1.

[0058] Furthermore, the power of the optical output signal of each of the multiple optical transmission devices 3 will be almost identical if they have the same function. However, considering the differences in function (for example, differences in optical signal processing function) and the effects of individual differences, the embodiment describes an example of managing the power on a device-by-device basis.

[0059] Let's continue explaining the parameters. Let the allowable loss in the transmission section be a [dBm]. Let the threshold of the k-th optical transmission device 3 be s(k) [dBm]. Let the number of optical transmission devices 3 be N (where N is an integer greater than or equal to 2). Note that in this example, the optical receiver 4 is not included in the number. Let the attenuation of the optical fiber be d [dB / km]. Let the transmission distance at k be l(k) [km].

[0060] (First Example) Figure 9 is a flowchart of the processing procedure for the first example. (Step S11) The monitoring and control device 5 sets the value of the allowable loss a for the transmission section in advance. Note that if it is necessary to change the value of the allowable loss a depending on the type of optical fiber used for the transmission section, the monitoring and control device 5 may set the value of the allowable loss a to a different value for each section.

[0061] (Step S12) Each optical transmission device 3 (or 3A) measures the power pin(k) of the optical input signal and notifies the monitoring and control device 5 of the information indicating the measured power pin(k) of the optical input signal.

[0062] (Step S13) The monitoring and control device 5 calculates the threshold value s(k) for each optical transmission device 3 (or 3A) using the following formula (1). Subsequently, the monitoring and control device 5 notifies each of the optical transmission devices 3 (or 3A) of the calculated threshold value s(k).

[0063] [Math. 1] s(k)=Pin(k)-a...(1)

[0064] (Step S14) Each optical transmission device 3 (or 3A) stores the threshold value s(k) output by the monitoring and control device 5 in its own storage unit 35.

[0065] (Step S15) Each optical transmission device 3 (or 3A) measures the power Pin(k) of the optical input signal at predetermined time intervals.

[0066] (Step S16) Each optical transmission device 3 (or 3A) compares the measured power Pin(k) of the optical input signal with the threshold s(k) stored in the memory unit 35 to determine whether the power Pin(k) of the optical input signal is less than the threshold s(k). If the power Pin(k) of the optical input signal is less than the threshold s(k) (Step S16; YES), each optical transmission device 3 (or 3A) proceeds to the process in Step S17. If the power Pin(k) of the optical input signal is greater than or equal to the threshold s(k) (Step S16; NO), each optical transmission device 3 (or 3A) returns to the process in Step S15.

[0067] (Step S17) Each optical transmission device 3 (or 3A) notifies the monitoring and control device 5 of an abnormality detection result indicating that an abnormality has been detected.

[0068] Based on the received anomaly detection results, the monitoring and control device 5 notifies, for example, an external device used by an administrator managing the optical transmission system 1.

[0069] (Second Example) Figure 10 is a flowchart of the processing procedure for the second example. (Step S21) The monitoring and control device 5 pre-sets the values ​​of the transmission section distance l (k), the optical fiber attenuation d, and the allowable loss a of the transmission section. Note that if it is necessary to change the values ​​of the attenuation d or the allowable value a depending on the type of optical fiber used in the transmission section, the monitoring and control device 5 may set at least one of the values ​​of the attenuation d and the allowable value a to a different value for each section.

[0070] (Step S22) Each optical transmission device 3 (or 3A) measures the power output (k) of the optical output signal and notifies the monitoring and control device 5 of the information indicating the measured power output (k) of the optical output signal. Note that the power output (k) of the optical output signal is measured when the output is normal or in its initial state.

[0071] (Step S23) The monitoring and control device 5 uses the power output(k) of the optical output signal acquired from each optical transmission value device to calculate the amount of loss in section k using the following equation (2), and sets the calculated amount of loss as the power of the optical input signal.

[0072] [Math. 2] Pin (k) = Pout (k) - {l (k) × d} ... (2)

[0073] (Step S24) The monitoring and control device 5 calculates the threshold s(k) for each of the optical transmission devices 3 (or 3A) using the following formula (3). Subsequently, the monitoring and control device 5 notifies each of the optical transmission devices 3 (or 3A) of the calculated threshold s(k).

[0074] [Math. 3] s(k)=Pin(k)-a=Pout(k)-{l(k)×d}-a...(3)

[0075] (Step S25) Each optical transmission device 3 (or 3A) stores the threshold value s(k) output by the monitoring and control device 5 in its own storage unit 35.

[0076] (Step S26) Each optical transmission device 3 (or 3A) measures the power Pin(k) of the optical input signal at predetermined time intervals.

[0077] (Step S27) Each optical transmission device 3 (or 3A) compares the measured power Pin(k) of the optical input signal with the threshold s(k) stored in the storage unit 35 to determine whether the power Pin(k) of the optical input signal is less than the threshold s(k). If the power Pin(k) of the optical input signal is less than the threshold s(k) (Step S27; YES), each optical transmission device 3 (or 3A) proceeds to the process in Step S17. If the power Pin(k) of the optical input signal is greater than or equal to the threshold s(k) (Step S27; NO), each optical transmission device 3 (or 3A) returns to the process in Step S15.

[0078] (Step S28) Each optical transmission device 3 (or 3A) notifies the monitoring and control device 5 of an abnormality detection result indicating that an abnormality has been detected.

[0079] Based on the received anomaly detection results, the monitoring and control device 5 notifies, for example, an external device used by an administrator managing the optical transmission system 1.

[0080] Thus, in this embodiment, an allowable loss limit for the transmission section is set, and the power reduction threshold is determined from the distance of the transmission section in each device. It should be noted that in digital optical transmission, the need to detect power reduction depending on distance is low, and conventional technology did not have a comparable mechanism.

[0081] The procedures for each embodiment described using Figures 9 and 10 are examples only and are not limited thereto. For example, other processes may be performed.

[0082] As described above, in this embodiment, the monitoring and control device 5 determines a threshold value for fault detection for each line using the measured value (or initial value) of the power of the optical input signal when it is normal. Alternatively, in this embodiment, the monitoring and control device 5 determines a threshold value for fault detection for each line using the power of the optical output signal, the attenuation rate of the optical fiber, and the distance of the transmission section as raw information used to calculate the theoretical value of the power of the optical input signal.

[0083] In the optical transmission system 1 configured in this way, since the threshold used for fault detection is determined for each line in optical transmissions with different transmission distances, as described above, it becomes possible to appropriately identify and monitor the degradation of the transmission section.

[0084] (Comparison with Comparative Example) Here, in order to further explain the effects of this embodiment, we will explain it in comparison with a comparative example. In the comparative example, it is assumed that abnormalities in the optical transmission system are detected by the monitoring and control units of each device. Also, it is assumed that the first device and the second device are connected by a 20 km optical fiber, and the second device and the third device are connected by a 30 km optical fiber. The power of the optical input signal to the first device is a ｉｎ (dBm), the power of the optical input signal to the second device is b ｉｎ (dBm), the power of the optical input signal to the third device is c ｉｎ Let the power be (dBm). Also, let the attenuation of the optical fiber be d (dBm / km), and the anomaly detection threshold detected by the monitoring and control unit be s (dBm). Furthermore, assume that the power of the optical output signal of each device (excluding individual differences) is constant at P (dBm) when there is no fault.

[0085] Under the above conditions, when there is no abnormality in the transmission section, each optical input signal power is b ｉｎ = P - 20d, c ｉｎ = P - 30d, and b ｉｎ > c ｉｎ > s. On the other hand, when some abnormality occurs in the transmission section and a loss of t (dB) occurs, each optical input signal power when an abnormality occurs in the 20 (km) section is b ｉｎ = P - 20d - t, and when an abnormality occurs in the 30 (km) section, c ｉｎ = P - 30d - t. In this case, depending on the value of t, b ｉｎ > s > c ｉｎ may occur. That is, in the comparative example, an abnormality can be detected in the 30 (km) section because the optical input power is below the threshold s, but an abnormality can be detected in the 30 (km) section because the optical input power is below the threshold s, while an abnormality cannot be detected in the 20 (km) section because the optical input power does not fall below the threshold s. Thus, in the comparative example, since the threshold s of each device is the same, there are cases where an abnormality cannot be detected quickly.

[0086] In contrast, according to the above-described present embodiment and each example, since the threshold of each device is changed according to the transmission path, an abnormality in the transmission path can be detected quickly.

[0087] As described above, the embodiments of this invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and designs and the like within the scope not departing from the gist of this invention are also included.

[0088] <Notes> (1): An optical transmission system for transmitting analog optical signals comprises an optical transmitter that converts electrical signals into optical signals and outputs them, an optical transmission device that transmits optical signals, and an optical receiver that converts optical signals into electrical signals and outputs them. At least one of the optical transmission device and the optical receiver has a mechanism for monitoring a decrease in the power of the input optical signal, and a function for dynamically controlling a power threshold for detecting the decrease. (2-1): The optical transmission system described in (1) above further comprises a monitoring control device. The monitoring control device has a function for collecting either or all of the values ​​of the output power of the optical signal from the optical transmitter and the optical transmission device, and the input power of the optical signal from the optical transmission device and the optical receiver, and for determining and notifying a threshold for detecting a decrease in the input power of the optical signal using these values. (2-2): In the optical transmission system described in (1) above, the monitoring control method of the monitoring control device in the optical transmission system further comprising a monitoring control device collects either or all of the values ​​of the output power of the optical signal from the optical transmitter and optical transmission device, and the input power of the optical signal from the optical transmission device and optical receiver, and uses these values ​​to determine and notify a threshold for detecting a decrease in the input power of the optical signal. (3): In the optical transmission system described in (2) above, the optical transmitter has a function to monitor the power of the output optical signal at regular intervals and notify the monitoring control device. (4): In the optical transmission device described in (2) above, the optical transmission device has a function to monitor the power of the input optical signal and the output optical signal at regular intervals and notify the monitoring control device of either or all of these values. (5): In the optical receiver described in (2) above, the optical receiver has a function to monitor the power of the input optical signal at regular intervals and notify the monitoring control device. (6-1): A transmission system for transmitting analog optical signals comprises an optical transmitter that converts electrical signals into optical signals using an FM (frequency modulation) batch conversion method and outputs them, an optical transmission device that transmits optical signals, and an optical receiver that converts optical signals into electrical signals and outputs them. The optical transmission device has a mechanism for monitoring a decrease in the power of the input optical signal, and includes a function for dynamically controlling a power threshold for detecting the decrease.(6-2): An optical transmission system for transmitting analog optical signals comprises an optical transmitter that converts electrical signals into optical signals using an FM (frequency modulation) batch conversion method and outputs them, an optical transmission device that transmits optical signals, and an optical receiver that converts optical signals into electrical signals and outputs them. The optical receiver has a mechanism for monitoring a decrease in the power of the input optical signal, and includes a function for dynamically controlling a power threshold for detecting the decrease. (7-1): A monitoring and control device in an optical transmission system comprising the monitoring and control device described in (6-1) or (6-2) above, which includes a function for collecting either or all of the values ​​of the output power of the optical signal from the optical transmitter and optical transmission device, or the input power of the optical signal from the optical transmission device and optical receiver, and for determining and notifying a threshold for detecting a decrease in the input power of the optical signal using these values. (7-2): A monitoring and control method for a monitoring and control device in an optical transmission system equipped with the monitoring and control device described in (6-1) or (6-2) above, wherein the device collects either or all of the values ​​of the output power of the optical signal from the optical transmitter and optical transmission device, and the input power of the optical signal from the optical transmission device and optical receiver, and uses these values ​​to determine and notify a threshold for detecting a decrease in the input power of the optical signal. (8): In the optical transmission system described in (7-1) or (7-2) above, the optical transmitter has a function to monitor the power of the output optical signal at regular intervals and notify the monitoring and control device. (9): In the optical transmission device described in (7-1) or (7-2) above, it has a function to monitor the power of the input optical signal and the output optical signal at regular intervals and notify the monitoring and control device of either or all of these values. (10): In the optical receiver described in (7-1) or (7-2) above, it has a function to monitor the power of the input optical signal at regular intervals and notify the monitoring and control device.

[0089] The present invention is applicable to optical signal transmission systems, optical signal transmitting devices, optical signal receiving devices, and monitoring and control devices that monitor and control optical signal transmission devices that transmit optical signals.

[0090] 1, 1A...Optical transmission system, 2...Optical transmission device, 3, 3A, 3-1, ..., 3-n, 3A-1, ..., 3A-n...Optical transmission device, 4, 4A...Optical receiving device, 5...Monitoring and control device, 31, 31A...Optical signal processing unit, 32...Optical amplification unit, 33, 33A...Optical signal distribution unit, 34...Notification unit, 35, 35A...Storage unit, 41, 41A...Conversion unit, 42...Demodulation unit, 43...Amplification unit, 44...Notification unit, 45, 45A...Storage unit, 52, 362, 462...Monitoring unit, 53, 363, 463...Setting unit, 54, 364, 464...Notification unit, 55, 365, 465...Storage unit

Claims

1. An optical transmission system for transmitting analog optical signals, comprising: an optical transmitting device that converts an electrical signal into an optical signal and outputs it; a plurality of optical transmission devices that transmit the optical signal; and an optical receiving device that converts the optical signal into an electrical signal and outputs it, wherein the optical transmission control device comprises: a monitoring unit that monitors a decrease in the power of the optical input signal input to the optical transmission device; and a setting unit that sets a power threshold for detecting a decrease in the power of the optical input signal for each of the plurality of optical transmission devices.

2. The optical transmission control device according to claim 1, wherein the optical transmission control device acquires any or all of the following values: information indicating the power of the optical output signal output from the optical transmitting device and the optical transmission device, and information indicating the power of the optical input signal from the optical transmission device and the optical receiving device; determines the threshold for detecting a decrease in the power of the optical input signal using the acquired values; and notifies a plurality of optical transmission devices of the determined threshold.

3. The setting unit sets an allowable value according to the type of transmission path used in the transmission section, and the order as seen from the optical transmission device is k, the monitoring unit acquires information indicating the power of the optical input signal from the optical transmission device and the optical receiving device, and the setting unit sets the threshold value of the k-th optical transmission device by dividing the power value of the optical input signal of the k-th optical transmission device by the allowable value, the optical transmission control device according to claim 1.

4. The setting unit sets an allowable value according to the type of optical fiber used in the transmission section, and the order as seen from the optical transmission device is k; the monitoring unit acquires information indicating the power of the optical output signals output from the optical transmission device and the optical receiving device; and the setting unit sets the threshold value for the k-th optical transmission device by dividing the value obtained by multiplying the distance of the transmission section from the power of the optical output signal of the k-th optical transmission device to the k-th section by the attenuation of the transmission path by the allowable value.

5. The optical transmission control device according to claim 1, wherein the monitoring unit monitors the power of the optical input signal input to the optical transmission device and the power of the optical output signal output from the optical transmission device at predetermined time intervals and acquires any or all of these values.

6. The optical transmission control device according to claim 1, wherein the optical transmitting device converts an electrical signal into an optical signal using an FM (frequency modulation) batch conversion method and outputs it, and the optical receiving device converts the optical signal into an electrical signal and outputs it.

7. An optical transmission system for transmitting analog optical signals, comprising: an optical transmitting device that converts an electrical signal into an optical signal and outputs it; a plurality of optical transmission devices that transmit the optical signal; and an optical receiving device that converts the optical signal into an electrical signal and outputs it, wherein the optical transmission device comprises: a monitoring unit that monitors a decrease in the power of an optical input signal input to the optical transmission device; and a setting unit that sets a power threshold for detecting a decrease in the power of the optical input signal for each of the plurality of optical transmission devices.

8. An optical transmission system for transmitting analog optical signals, comprising an optical transmitting device that converts an electrical signal into an optical signal and outputs it, a plurality of optical transmission devices that transmit the optical signal, and an optical receiving device that converts the optical signal into an electrical signal and outputs it, wherein a monitoring unit monitors a decrease in the power of the optical input signal input to the optical transmission device, and a setting unit sets a power threshold for detecting a decrease in the power of the optical input signal for each of the plurality of optical transmission devices.

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