Abnormality detection system

Abstract

This abnormality detection system comprises a data processing device 1 and a plurality of optical monitoring devices 30 arranged at connection points 3 for respective sections of an optical cable forming an optical access network. The optical monitoring device 30 acquires image data obtained by receiving, with an image sensor 33, a plurality of optical signals passing through respective ones of a plurality of cores accommodated in the optical cable. The data processing device 1 obtains an optical power value of each of the plurality of optical signals from the image data, and detects a current abnormality or predicts a future abnormality for each of the plurality of cores.

Description

Abnormal Detection System

[0001] The present disclosure relates to an abnormal detection system.

[0002] In recent years, based on the concept of Innovative Optical and Wireless Network (IOWN), which has attracted attention as a next-generation network technology, the expansion of optical access networks has been accelerating. IOWN is based on optical communication technology and realizes low latency, high bandwidth, and power saving, providing an infrastructure to support a wider variety of services and applications than ever before. While the range of use of optical access networks is expanding, the complexity of the network is also increasing.

[0003] Watanabe Hiroshi, et al., "Remote Optical Path Switching Node Operated in a Multi-Stage Loop-Type Optical Access Network", 2021 Institute of Electronics, Information and Communication Engineers Communication Society Conference, BK-2-3

[0004] When an abnormality occurs in an optical access network, the work of identifying the abnormal location is started based on a report from a user or an alarm from a device. In the work of identifying the optical cable section, an operator goes to the site and conducts a pulse test on each core wire. When measuring a plurality of core wires, it is necessary to switch and measure one by one. Therefore, there have been cases where a lot of time is required to identify the cause. In order to minimize the impact on the service, early detection of the abnormal location is required.

[0005] In addition, since the work of identifying the abnormal location is started based on a report from a user or an alarm from a device, there is a problem that even if an abnormality occurs, it cannot be noticed immediately and the work cannot be started until the service is affected.

[0006] The present disclosure has been made in view of the above, and aims to reduce the time and operation required to identify the cause of a failure in an optical access network.

[0007] An anomaly detection system according to one aspect of the present disclosure is an anomaly detection system comprising a plurality of optical monitoring devices and a data processing device arranged at connection points for each section of an optical cable constituting an optical access network, wherein the optical monitoring device acquires image data by receiving a plurality of optical signals passing through each of a plurality of cores housed in the optical cable with an image sensor, and the data processing device determines the optical power value of each of the plurality of optical signals from the image data and detects an anomaly at the present time or estimates a future anomaly for each of the plurality of cores.

[0008] According to this disclosure, the time and effort required to identify the cause of failures in optical access networks can be reduced.

[0009] Figure 1 shows an example of an optical access network. Figure 2 shows an example of an optical monitoring device. Figure 3 shows an example of a data processing device. Figure 4 is a flowchart showing an example of the processing flow of a data processing device. Figure 5 shows an example of a table of optical power values. Figure 6 shows an example of a table of optical power values ​​measured by optical monitoring devices along the route. Figure 7 shows an example of a table of optical power values ​​measured by optical monitoring devices along the route. Figure 8 shows an example of the aggregated results of loss increase. Figure 9 shows an example of the results of measuring loss for optical signals of different wavelengths. Figure 10 shows an example of the hardware configuration of a data processing device.

[0010] [Optical Access Network] Referring to Figure 1, an example of an optical access network monitored by the anomaly detection system of this embodiment will be described. An optical access network is a network system that achieves high-speed and high-capacity communication by using optical fibers in the access section connecting telecommunications carriers and end users such as homes and businesses.

[0011] Optical transmission equipment 2 is installed in the telecommunications carrier's building. Optical transmission equipment 2 transmits optical signals to each core of the optical cable. The optical cable is, for example, a multi-core optical cable in which multiple optical fibers (also called cores) are housed in a single cable. The optical cable is housed in an optical cable termination rack 4 within the telecommunications building.

[0012] In the anomaly detection system of this embodiment, the optical transmission device 2 that is in service or the optical transmission device 2 that is not in service may be used as the device that transmits an optical signal for detecting or estimating the location of an anomaly. The optical transmission device 2 that is in service transmits an optical signal continuously, while the optical transmission device 2 that is not in service transmits an optical signal periodically. A light source may be used instead of the optical transmission device 2. The light source may be capable of transmitting light of multiple different wavelengths.

[0013] The optical cable is branched at connection points 3B to 3J to form a predetermined number of cores. In the example in Figure 1, section 1 between the optical cable termination rack 4 and connection point 3B is connected by a 1000-core optical cable. At connection point 3B, the 1000-core optical cable is branched into a 400-core optical cable and a 600-core optical cable. The 400-core optical cable connects section 2 between connection point 3B and connection point 3C. At connection point 3C, the 400-core optical cable is branched into two 200-core optical cables. Each of the 200-core optical cables connects section 3 between connection point 3C and connection point 3D, and section 4 between connection point 3C and connection point 3E. At the terminal connection points 3D and 3E, each core is branched and connected to the end user. Similarly, the optical cables from section 5 to section 9 are also branched at connection points 3F to 3J to form a predetermined number of cores.

[0014] Optical monitoring devices 30A to 30J are installed at each of the optical cable termination racks 4 (the connection point between the optical transmission device 2 and the optical cable) and connection points 3B to 3J. For example, termination racks, closures, or remote optical path switching nodes as described in Non-Patent Document 1 are placed at connection points 3B to 3J, and optical monitoring devices 30B to 30J are attached to all the fiber optics. Hereinafter, when the optical cable termination rack 4 and connection points 3B to 3J are not distinguished, they may be referred to as connection point 3. When the optical monitoring devices 30A to 30J are not distinguished, they may be referred to as optical monitoring device 30.

[0015] The optical monitoring device 30 monitors the optical signals passing through all the fiber cores at the connection point 3. Specifically, the optical monitoring device 30 extracts a portion of the optical signal passing through each fiber core and receives it with an image sensor. For example, when monitoring an optical cable with 1000 fiber cores, image data is obtained by capturing 1000 optical signals with the image sensor.

[0016] The optical monitoring device 30 periodically captures optical signals and transmits the captured image data to the data processing device 1. The method of transmitting the image data can be wireless or wired, or any other method.

[0017] Figure 2 shows an example of the configuration of the optical monitoring device 30. The optical monitoring device 30 shown in the figure comprises a prism 31, a connection part 32, and an image sensor 33.

[0018] The optical cable 100 is connected to the connection part 32. The optical signal passing through each core of the optical cable 100 is shone from the connection part 32 onto the prism 31, passes through the prism 31, and is coupled to each core of the opposing optical cable 100. A portion of the optical signal is reflected by Fresnel reflection at the interface of the prism 31, and the reflected light is received by the image sensor 33.

[0019] The image sensor 33 receives the reflected light from each core wire at a grid (pixel) corresponding to each core wire, and obtains image data for each grid. The pixel value (e.g., brightness) of each grid in the image data is determined by the light intensity of the reflected light received by the grid, the exposure time, and the sensitivity of the grid. Since the arrangement of each core wire is adjusted at the connection section 32, the reflected light received by the image sensor 33 is aligned and positioned at predetermined locations on each grid.

[0020] By using the optical monitoring device 30, the optical power of the communication light in all the cores of the optical cable 100 can be measured at once.

[0021] A portion of the optical signal may be extracted using an optical power coupler instead of the prism 31, or by other means. The port monitoring function of the remote optical path switching node described in Non-Patent Document 1 may be used as the optical monitoring device 30.

[0022] The data processing device 1 is located, for example, in a maintenance center and receives image data from each of the optical monitoring devices 30. The data processing device 1 analyzes the received image data to determine the optical power value for each fiber and manages the optical power value for each fiber and each optical monitoring device. Based on the optical power value, the data processing device 1 detects abnormal locations, estimates locations that may become abnormal in the future, and estimates the cause of such abnormalities.

[0023] [Data Processing Device] Referring to Figure 3, an example of the configuration of the data processing device 1 will be described. The data processing device 1 shown in the figure comprises a receiving unit 11, an analysis unit 12, a management unit 13, and a detection unit 14.

[0024] The receiving unit 11 receives image data from each optical monitoring device 30, which captures the optical signals passing through each core wire.

[0025] The analysis unit 12 analyzes the image data and determines the optical power value for each fiber in each optical monitoring device 30A to 30J. For example, the analysis unit 12 determines the optical power value of the optical signal that has passed through each fiber based on the pixel value corresponding to each fiber in the image data.

[0026] The management unit 13 manages the optical power value for each fiber and each optical monitoring device 30. The management unit 13 may also manage the amount of loss increase for each period from the time-series optical power values.

[0027] The detection unit 14 detects current anomalies or estimates future anomalies based on the optical power value.

[0028] [Method for proactively detecting abnormal locations] Referring to the flowchart in Figure 4, an example of the process flow in which the data processing device 1 proactively detects abnormal locations will be explained.

[0029] The process shown in Figure 4 is performed periodically during normal operation when there are no user reports or device alarms. The data processing device 1 receives and analyzes image data from each optical monitoring device 30 and determines the optical power value of each core wire at each optical monitoring device 30.

[0030] In step S11, the data processing device 1 determines whether the current optical power value measured by the terminal optical monitoring device 30 for each fiber is appropriate. For example, the data processing device 1 determines that the current optical power value is not appropriate if it is less than or equal to a specified value (e.g., 1 dB) below the appropriate value. In the example in Figure 1, optical monitoring devices 30D, 30E, 30H, 30I, and 30J are the terminal optical monitoring devices. The appropriate value is the optical power value of each fiber measured when the optical cable was laid, and is used as a reference.

[0031] Figure 5 shows an example of a table of optical power values ​​measured by the optical monitoring device 30D managed by the data processing device 1. In the example shown in the figure, the appropriate value and current value of the optical power at the location where the optical monitoring device 30D is installed are shown for each of the 200 core wires connected to the optical monitoring device 30D. In the example in Figure 5, the current value of the optical power of core wire number 3 was determined to be less than the appropriate value by a specified value or more at the optical monitoring device 30D at the end of the line.

[0032] If the current value of the optical power is appropriate, in step S12 the data processing device 1 determines that the fiber is normal and performs the process in step S11 for the next fiber.

[0033] If the current optical power value is not appropriate, in step S13, the data processing device 1 determines whether the amount of loss increase in each section along the route of the optical fiber that was determined to be inappropriate is appropriate. The route refers to the path from the optical transmission device 2 of the communication building to the optical monitoring device 30 at the end. The amount of loss increase in each section can be determined by the difference in optical power values ​​measured at the optical monitoring devices 30 at both ends of each section. If the amount of loss increase is excessive compared to the length of the section, the data processing device 1 determines that the amount of loss increase in that section is inappropriate.

[0034] Figures 6 and 7 show an example of a table of optical power values ​​measured by optical monitoring devices 30A to 30D along the route of the third fiber. The route of the third fiber consists of sections 1, 2, and 3 in Figure 1, and the optical power value is measured at each of the optical monitoring devices 30A to 30D. In the example in Figure 6, an excessive loss increase is observed in section 1 between optical monitoring device 30A and optical monitoring device 30B. In the example in Figure 7, the loss increase is appropriate in all sections 1, 2, and 3.

[0035] If there is a section where the loss increase is excessive, in step S14, the data processing device 1 determines that the section with the excessive loss increase is an abnormal section. In the example in Figure 6, section 1 is determined to be an abnormal section.

[0036] If there is no section with an excessive increase in loss, in step S15, the data processing device 1 determines that the optical transmission device 2 (or the communication building) is the abnormal location. In the example in Figure 7, the optical transmission device 2 is determined to be the abnormal location.

[0037] The abnormal locations identified in steps S14 and S15 are notified to the maintenance personnel.

[0038] [Method for estimating areas that may become abnormal in the future] Next, we will explain an example of a method for estimating areas that may become abnormal in the future.

[0039] The data processing device 1 calculates the amount of loss increase for each optical monitoring device 30 over time for all optical fibers at predetermined intervals (e.g., every month). The data processing device 1 then aggregates the results of determining whether the loss increased for a predetermined period (e.g., three consecutive months) and the average amount of loss increase over the predetermined period for each optical fiber and each optical monitoring device. For example, the data processing device 1 uses data from the beginning of each month for the most recent three months to determine the monthly amount of loss increase for each optical monitoring device 30 and calculate the average amount of loss increase.

[0040] The data processing device 1 picks out optical monitoring devices 30 or sections where the loss has been continuously increasing for a predetermined period and the average increase is equal to or greater than a specified value (e.g., 1 dB), and notifies the maintenance personnel that these are locations that may become abnormal in the future.

[0041] Fig. 8 shows an example of the aggregation result of the loss increase amount. In the example of this figure, the loss of the first core wire has been increasing continuously for three months in the optical monitoring device 30B, and the average increase amount exceeds 1 dB. Therefore, the data processing device 1 issues an alarm for the section 1 between the optical monitoring device 30A and the optical monitoring device 30B.

[0042] [Method for estimating the cause of a location that may become abnormal in the future] Next, an example of a method for estimating the cause of a location that may become abnormal in the future will be described. <了

[0043] In optical communication, optical signals in the wavelength band from 1260 nm to 1675 nm are used. In the case of a connection failure, the influence on the communication quality appears to be greater for shorter wavelengths than for longer wavelengths. On the other hand, when a mechanical characteristic load is applied, the influence on the communication quality appears to be greater for longer wavelengths than for shorter wavelengths. The mechanical characteristic load refers to physical forces such as bending, side pressure, dropping, and vibration on the optical fiber.

[0044] Therefore, in the present embodiment, by changing the wavelength of the optical signal and measuring the loss, it is estimated whether the cause of a location that may become abnormal in the future is a connection failure or due to a mechanical characteristic load.

[0045] For example, if it is estimated from the aggregation result of Fig. 8 that there is a possibility of abnormality in the future in section 1 of the first core wire, optical signals with different wavelengths are transmitted from a wavelength-variable light source in the communication building to the first core wire, and for each optical signal with a different wavelength, the loss of section 1 is measured. If an abnormality is observed for the optical signal on the shorter wavelength side, it is estimated that the cause is a connection failure, and if an abnormality is observed for the optical signal on the longer wavelength side, it is estimated that the cause is a mechanical characteristic load.

[0046] Fig. 9 shows an example of the results of measuring the loss for each optical signal with a different wavelength. In the example of this figure, an abnormality is observed for the first core wire with a long wavelength optical signal, and an abnormality is observed for the 200th core wire with a short wavelength optical signal. Therefore, the data processing device 1 estimates that the first core wire may become abnormal in the future due to a mechanical characteristic load, and the 200th core wire may become abnormal in the future due to a connection failure.

[0047] As described above, the abnormality detection system of the present embodiment includes a plurality of optical monitoring devices 30 arranged at connection points 3 for each section of an optical cable constituting an optical access network and a data processing device 1. The optical monitoring device 30 acquires image data obtained by receiving a plurality of optical signals passing through each of a plurality of optical fibers housed in the optical cable with an image sensor 33. The data processing device 1 obtains the optical power value of each of the plurality of optical signals from the image data, and detects an abnormality at the current time or estimates a future abnormality for each of the plurality of optical fibers. As a result, it becomes possible to periodically measure the optical power value without the operator going to the site. When an abnormality occurs in the optical access network, it is possible to immediately detect the presence or absence of the abnormality and narrow down the abnormal location. In addition, by utilizing the acquired data, it is possible to estimate a location where an abnormality may occur in the future and lead to preventive maintenance.

[0048] For the data processing device 1 described above, for example, a general-purpose computer system including a central processing unit (CPU) 901, a memory 902, a storage 903, a communication device 904, an input device 905, and an output device 906 as shown in FIG. 10 can be used. In this computer system, the data processing device 1 is realized by the CPU 901 executing a predetermined program loaded on the memory 902. This program can be recorded on a non-temporary recording medium readable by a computer, such as a magnetic disk, an optical disk, or a semiconductor memory, or can be distributed via a network.

[0049] 1. Data processing device 11. Receiving unit 12. Analysis unit 13. Management unit 14. Detection unit 2. Optical transmission device 3, 3B - 3J. Connection point 30, 30A - 30J. Optical monitoring device 31. Prism 32. Connection part 33. Image sensor 4. Optical cable termination rack

Claims

1. An anomaly detection system comprising a plurality of optical monitoring devices and data processing devices arranged at connection points for each section of an optical cable constituting an optical access network, wherein the optical monitoring device acquires image data by receiving a plurality of optical signals passing through each of the plurality of cores housed in the optical cable with an image sensor, and the data processing device determines the optical power value of each of the plurality of optical signals from the image data, and detects an anomaly at the present time or estimates an anomaly in each of the plurality of cores.

2. An anomaly detection system according to claim 1, wherein the data processing device detects an anomaly based on the optical power value of an optical signal passing through the terminal section of each route of the optical access network, and detects the section in which the anomaly occurred by calculating the increment of loss for each section on the route in which the anomaly was detected.

3. An anomaly detection system according to claim 1, wherein the data processing device uses the time-series optical power values ​​at the connection point to determine the amount of loss change due to time change and estimates future anomalies.

4. An anomaly detection system according to claim 1, comprising transmitting optical signals of different wavelengths to a fiber optic cable, measuring the loss of the fiber optic cable for each of the optical signals of different wavelengths, and estimating the cause of a future anomaly based on the loss for each wavelength.

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