Optical signal quality calculation method for optical communication network and optical signal quality calculation device

Abstract

The present invention makes it possible to accurately measure, so as to correctly ascertain, the optical signal quality for each node even under such a situation that arbitrarily-defined machines are connected to a transmission end and a reception end of an optical communication network like interconnection of optical communication networks among a plurality of communication carriers, and the signal speed, the modulation system, or the like is changed. In the processing before service activation, specific terminals having known characteristics are connected to the transmission end and the reception end, and a result obtained by measuring a quality value for each of a plurality of cases is registered in a database as a reference value. At the time of activating the service and thereafter, arbitrarily-defined terminals are connected to the transmission end and the reception end, and the quality value of an optical signal is measured at each node position. In a situation such as when an abnormality occurs, a reference value corresponding to a specific case similar to the current situation is extracted from the database, and a failure occurrence section is estimated by using a result obtained by correcting the measured value by using the reference value.

Description

Optical signal quality calculation method and optical signal quality calculation device for optical communication network

[0001] The present invention relates to an optical signal quality calculation method and an optical signal quality calculation device for an optical communication network.

[0002] For example, when providing a communication service by connecting multiple users at distant locations via optical paths, an optical communication relay network 10 having the configuration shown in Fig. 1 is used. This optical communication relay network 10 is configured as an all-photonics network (APN), that is, it is configured to occupy optical wavelengths in all sections of the communication network.

[0003] 1 includes multiple APN gateways 11 and 12, multiple APN interchanges 13-1 to 13-3 and 14-1 to 14-3, and multiple optical fiber transmission paths 15 and 16. For example, one user is connected to the APN gateway 11 via an APN transceiver that is a transmitting end terminal 21, and the other user is connected to the APN gateway 12 via an APN transceiver that is a receiving end terminal 22.

[0004] Therefore, an optical path can be connected between multiple users via the transmitting end terminal 21, APN gateway 11, multiple APN interchanges 13-1 to 13-3, APN gateway 12, and receiving end terminal 22. It is also possible to connect an optical path between multiple users via the transmitting end terminal 21, APN gateway 11, multiple APN interchanges 14-1 to 14-3, APN gateway 12, and receiving end terminal 22.

[0005] When actually operating an optical communication relay network 10 such as that shown in Figure 1, it is necessary to equip it with various maintenance functions to maintain normal communication functions. Therefore, optical signal quality measurement monitors 17-1 to 17-5 are connected to each node position that relays optical signals, such as the APN gateway 11, each APN interchange 13-1, 13-2, 13-3, and the APN gateway 12. In the figure, the optical signal quality measurement monitors 17-1 to 17-5 are abbreviated as "MON."

[0006] That is, when checking optical signal quality using values ​​such as the optical signal to noise ratio (OSNR) or spectral width, which are subject to cumulative quality degradation with each relay, it is necessary to measure the quality of the optical signal at each node that relays the optical signal. By performing such measurements, it becomes possible to check the quality of the optical signal for each section of the optical fiber transmission line 15, etc., and to identify the location of an abnormality when it occurs. It also becomes possible to estimate sections or devices that are likely to fail before a failure occurs, and to implement preventive maintenance measures.

[0007] When actually measuring optical signal quality, it is expected that the OSNR, which is considered to be the mainstream optical signal quality index, will be measured (see Non-Patent Document 1). In addition, in order to measure the OSNR without interrupting service, it is expected that the OSNR will be estimated by measuring the power of the AC component after converting the optical signal to an electrical signal.

[0008] Yoshida et al., "OSNR Monitor Unit and Optical Node Prototype for Dynamic and Flexible Optical Networks," IEICE Technical Report OSC2018-17, 2018.

[0009] In an optical communication relay network 10 configured as shown in Figure 1, when the optical signal path passing through the APN gateway 11, each APN interchange 13-1, 13-2, 13-3, and APN gateway 12 is to be monitored, it is generally assumed that processing will be carried out in the order of steps (1) to (6) as described below.

[0010] (1) As shown in Figure 1, optical signal quality measurement monitors 17-1 to 17-5 are connected to each node position. (2) Specific terminals are connected as the transmitting end terminal 21 and the receiving end terminal 22. (3) Measurements are performed by each of the optical signal quality measurement monitors 17-1 to 17-5, and after converting the optical signal to an electrical signal, the power of the AC component is measured to estimate the OSNR before correction. (4) A spectrum analyzer or other device is connected to each of the same node positions as the optical signal quality measurement monitors 17-1 to 17-5, and the correct OSNR value is identified for each node position from the measurement results. (5) Based on the following equation (1), the parameter constant C for each monitor is calculated from the measured values ​​of each of the optical signal quality measurement monitors 17-1 to 17-5 and the correct OSNR value. １ ~C ６ Uniquely identify the

[0011]

[0012] (6) Hereafter, the specified constant C １ ~C ６ Utilizing this, the correct OSNR value is calculated for each relay node position from the measurement results of each optical signal quality measurement monitor 17-1 to 17-5. For example, if a communication abnormality occurs in a relay path passing through the terminal 21, APN gateway 11, each APN interchange 13-1, 13-2, 13-3, APN gateway 12, and terminal 22, it is necessary to identify the relay section where the abnormality occurred. Therefore, measurements are performed by the optical signal quality measurement monitors 17-1 to 17-5 connected to each relay node position, and a quality value Q such as an OSNR value is calculated. ｎ is obtained for each node position.

[0013] As a result of the above processing, for example, the quality data E1 shown in FIG. 3A is a quality value Q １ ~Q ５ In the example of FIG. 3A, the quality value Q １ ~Q ５ are 37 [dB], 34.5 [dB], 34.2 [dB], 33 [dB], and 31.3 [dB], respectively, and the quality degradation in the section area A1 is abnormally large, so it can be assumed that there is an abnormality in the optical transmission line or equipment in the section between the two optical signal quality measurement monitors 17-1 and 17-2.

[0014] However, when the characteristics of the optical communication relay network 10 change, the constant C １ ~C ６ Specifically, when the models of the transmitting and receiving terminals 21 and 22 connected to the optical communication relay network 10 are changed, the accuracy of the OSNR measurement varies due to differences in the power of the input light, wavelength band, transmission speed, modulation method, baud rate, etc., the environment of the relay nodes and fibers, and individual differences in the measuring instruments. The same can be said for other quality indicators such as the spectral width, in addition to the OSNR.

[0015] In particular, in recent years, there is a possibility that an optical communication network of a different carrier than the carrier that manages the optical communication relay network 10 may be interconnected outside the optical communication relay network 10, and therefore, there is a possibility that any device with unknown specifications may be connected as each of the terminals 21 and 22. Therefore, the constant C １ ~C ６ When using this method, the correct optical signal quality cannot be determined.

[0016] Therefore, for example, in a situation where the correct quality data E0 shown in FIG. 3B should be measured, the quality data E1 shown in FIG. 3A may be measured. In the correct quality data E0 in FIG. 3B, the quality value Q １Ｃ ~Q ５Ｃ In the example of FIG. 3B, the quality value Q １Ｃ ~Q ５Ｃ are 36 [dB], 35 [dB], 34 [dB], 32.5 [dB], and 31.5 [dB], respectively, and the quality degradation in the section area A2 is abnormally large, so it can be estimated that there is actually an abnormality in the optical transmission line or equipment in the section between the two optical signal quality measurement monitors 17-3 and 17-4. However, the constant C １ ~C ６ If the above methods are used, it is expected that a large error will occur in the measurement of the optical signal quality due to their inappropriateness, and that the abnormal section will not be identified.

[0017] The present invention has been made in view of the above circumstances, and aims to provide an optical signal quality calculation method and an optical signal quality calculation device for an optical communication network that make it easy to grasp more accurate optical signal quality, regardless of differences in the speed or modulation method of the optical signal being relayed.

[0018] (1) In the method for calculating optical signal quality in an optical communication network of the present invention, under conditions in which normal communication is possible between a specific transmitting end device and a specific receiving end device via an optical communication relay network in which the transmitting end device and the receiving end device are connected, the results of performing a first optical signal quality measurement for each of a plurality of relay nodes on the optical communication relay network are retained as multiple sets of reference values ​​for each combination of the transmitting end device and the receiving end device and for each route; with an arbitrary transmitting end device and an arbitrary receiving end device connected to the optical communication relay network, performing a second optical signal quality measurement for each of a plurality of relay nodes on the optical communication relay network; extracting from the multiple sets of reference values ​​a specific case in which the route, transmitting end device, and receiving end device in the second optical signal quality measurement are similar; and correcting the result of the second optical signal quality measurement using the reference value corresponding to the specific case.

[0019] (2) The optical signal quality calculation device for an optical communication network of the present invention comprises: a reference value storage unit that stores the results of a first optical signal quality measurement performed on each of a plurality of relay nodes on the optical communication relay network as multiple sets of reference values ​​for each combination of the transmitting end device and the receiving end device and for each route, under a condition in which a specific transmitting end device and a specific receiving end device having known characteristics are each connected to the optical communication relay network and normal communication is possible between the transmitting end device and the receiving end device via the optical communication relay network; a measurement value collection unit that performs a second optical signal quality measurement on each of a plurality of relay nodes on the optical communication relay network and collects measurement values, under a condition in which an arbitrary transmitting end device and an arbitrary receiving end device are connected to the optical communication relay network; and a measurement value correction unit that extracts a specific case in which the route, transmitting end device, and receiving end device in the second optical signal quality measurement are similar from the multiple sets of reference values, and corrects the result of the second optical signal quality measurement using the reference value corresponding to the specific case.

[0020] According to the optical signal quality calculation method and optical signal quality calculation device for an optical communication network of the present invention, the results of optical signal quality measurement are corrected using the results of extracting a reference value with a high similarity from multiple sets of reference values ​​registered in advance, so that the optical signal quality can be grasped more accurately regardless of differences in the speed or modulation method of the optical signal being relayed.In addition, when a fault occurs, it becomes easy to correctly estimate the section where the abnormality occurs.

[0021] FIG. 1 is a block diagram showing an example of the configuration of a general optical communication relay network. FIG. 2 is a block diagram showing an example of the configuration of main parts of an optical communication relay network when a reference value is acquired when implementing the present invention. FIG. 3 is a graph showing examples of optical signal measurement results and correct quality data for each node in an optical communication relay network. FIG. 4 is a graph showing examples of optical signal measurement results and correct quality data for each node in an optical communication relay network. FIG. 5 is a schematic diagram showing an example of the configuration of a table in which reference values ​​are registered. FIG. 6 is a graph showing examples of optical signal quality measurement values, reference values, and corrected optical signal quality values. FIG. 7 is a graph showing examples of optical signal quality measurement values, reference values, and corrected optical signal quality values. FIG. 8 is a flowchart showing an example of a processing procedure when implementing the optical signal quality calculation method of the present invention. FIG. 9 is a block diagram showing an example of the configuration of an optical signal quality calculation device of the present invention. FIG. 10 is a block diagram showing another example of the configuration of an optical signal quality calculation device of the present invention.

[0022] An embodiment of the present invention will be described below with reference to the drawings. <Preparation required for implementing the optical signal quality calculation method> In the present invention, optical signal quality is calculated for an optical communication network such as the optical communication relay network 10 shown in Fig. 1. In order to enable the implementation of the present invention, a reference value is first obtained as a preparation before opening a communication service to a user.

[0023] An example of the configuration of the main parts of the optical communication relay network 60 when acquiring a reference value is shown in Fig. 2. When acquiring a reference value of an optical communication path passing through each of the relay nodes 23-1, 23-2, 23-3, 23-4, and 23-5 in Fig. 2, specific terminals 21R and 22R are connected to the transmitting end and receiving end of the optical communication relay network 60. Each of the specific terminals 21R and 22R is a device with known specifications or characteristics, and has known characteristics.

[0024] Optical signal quality monitors 171, 172, 173, 174, and 175 are connected to the relay nodes 23-1, 23-2, 23-3, 23-4, and 23-5, respectively. The optical signal quality monitors 171 to 175 are conventional, well-known measuring devices that can measure the OSNR value and spectral width of the optical signal.

[0025] 2, an operator, for example, confirms that normal communication is possible between the specific terminal 21R and the specific terminal 22R via the relay nodes N1 to N5 of the optical communication relay network 60. In this state, the optical signal quality measurement monitors 171 to 175 are used to measure the quality value Q of the optical signal at the positions of the relay nodes 23-1, 23-2, 23-3, 23-4, and 23-5, and the results are used as the reference value Q of each node position. １Ｒ ~Q ５Ｒ The measured reference value Q １Ｒ ~Q ５Ｒ is stored in the database together with information on each of the specific terminals 21R and 22R and route information.

[0026] For example, the worker prepares other specific terminals 21R and 22R of different models from those described above, and connects them to replace the transmitting and receiving end devices of the optical communication relay network 60. After it is confirmed that the specific terminals 21R and 22R after the replacement are in a state where normal communication can be performed between them via the optical communication relay network 60, the optical signal quality measurement monitors 171 to 175 are used to measure the quality values ​​Q of the optical signals at the positions of the relay nodes 23-1 to 23-5. The measurement results are also used as a new reference value Q. １Ｒ ~Q ５Ｒ The reference values ​​are stored in a database, for example in the form of a table, together with information about each of the specific terminals 21R and 22R and route information. By having an operator or the like repeat the above operation, it is possible to obtain a plurality of patterns of combinations of reference values ​​for each of the conditions of a plurality of types of specific terminals 21R and 22R.

[0027] <Configuration Example of Reference Value Table> Fig. 4 shows a configuration example of a reference value table 70 in which reference values ​​are registered. In the example of Fig. 4, information on reference values ​​for each of three types of patterns P01, P02, and P03 is registered as a table. In addition, as attributes of each pattern, information on a specific device connected to the transmitting end, information on a specific device connected to the receiving end, information common to the transmitting and receiving ends, route information, and a reference value for each node are registered.

[0028] In addition, information on the manufacturer name, model number, and transmission power range is registered as information on the specific device at the transmitting end.In addition, information on the manufacturer name, model number, and OSNR tolerance is registered as information on the specific device at the receiving end.In addition, information on the communication speed, modulation method, baud rate, and wavelength band is registered as information common to the transmitting and receiving ends.

[0029] The route information of each pattern in Fig. 4 represents a route similar to the case where the route passes through the five relay nodes 23-1, 23-2, 23-3, 23-4, and 23-5 shown in Fig. 2 in order. The five reference values ​​of the pattern P01 in Fig. 4 are the reference values ​​Q １Ｒ ~Q ５Ｒ are 37.0 [dB], 34.5 [dB], 34.2 [dB], 33.5 [dB], and 31.8 [dB].

[0030] That is, when the equipment of model number A001 of company A is connected to the transmitting end and the receiving end of the optical communication relay network 60, and the quality value of the optical signal at each node position is measured using each of the optical signal quality measurement monitors 171 to 175, the reference value Q to be registered as the pattern P01 in FIG. １Ｒ ~Q ５Ｒ In addition, information about the transmitting and receiving end devices, as well as information common to both the transmitting and receiving ends, can be identified from the company name, model number, operating status, etc. of the actually connected devices. The same applies to the other patterns P02 and P03.

[0031] <Data Processing After Preparations Are Completed> After the above preparations are completed and a database such as the reference value table 70 described above becomes available, for example, a telecommunications carrier managing the optical communication relay network 10 in Figure 2 can provide communication services to users. However, depending on the situation, any devices may be connected as the transmitting end terminal 21 and the receiving end terminal 22. Specifically, since the optical communication relay network 10 may be interconnected with an optical communication network of a different telecommunications carrier than the telecommunications carrier managing the optical communication relay network 10 via the terminals 21 and 22, the terminals 21 and 22 may change.

[0032] When any terminal 21, 22 is connected to the transmitting end and the receiving end, the state of the optical signal at each node of the optical communication relay network 10 changes, so the quality value Q measured by each optical signal quality measurement monitor 17-1 to 17-5 １ ~Q ５ It is expected that the quality data E1 shown in FIG. 3A will deviate from the correct quality data E0 shown in FIG. 3B.

[0033] Therefore, when the optical signal quality calculation method of the present invention is implemented, an appropriate reference value is extracted from the reference value table 70 created in advance, and this reference value is used to correct the measurement value.

[0034] Specifically, from among the multiple patterns registered in the reference value table 70, one optimal pattern that is similar to the current situation is identified, and a set of reference values ​​is obtained from the reference value table 70. For example, if communication between terminal 21 and terminal 22 in Fig. 1 fails, a pattern in which the route between terminals 21 and 22 matches the route information is identified on the reference value table 70. Furthermore, taking into consideration the similarity of the manufacturer names and model numbers of terminals 21 and 22, as well as conditions such as communication speed, modulation method, and wavelength band, the most similar pattern is identified, and the corresponding set of reference values ​​is obtained.

[0035] The reference value Q of each node position obtained by the above process １Ｒ ~Q ５Ｒ and the quality values ​​Q measured by the optical signal quality measurement monitors 17-1 to 17-5. １ ~Q ５ Based on this, the corrected quality value Q １Ｃ ~Q ５Ｃ can be calculated using the following formula (2): ｎｃ =Q ｎ -Q ｎＲ +F(n) ...(2) Q ｎｃ : Corrected value of nth node Q ｎ : Measurement value of nth node Q ｎＲ : Reference value of nth node F(n): Ideal value

[0036] Examples of the optical signal quality measurement value D1, the reference value D2, and the corrected optical signal quality value D3 are shown in FIGS. 5A to 5C. In this example, the ideal value F(n) is determined by the following equation (3). This ideal value F(n) is represented as a dashed line on the graphs shown in FIGS. 5A to 5C. F(n)=37-1.0n [dB] (3) In this case, the corrected optical signal quality value D3 is calculated for each node as follows: Q １Ｃ = 36 [dB] Q ２Ｃ = 35 [dB] Q ３Ｃ = 34 [dB] Q ４Ｃ =32.5[dB]Q ５Ｃ = 31.5 [dB]

[0037] <Example of Estimation of Section Where Abnormality Occurs> For example, when comparing the optical signal quality measurement value D1 shown in FIG. 5A between nodes, the quality value Q of the fourth node ４ is the third quality value Q ３ and the fifth quality value Q ５ Since the quality is somewhere in the middle of the 3rd and 4th range, it doesn't seem like there's a problem in the range between the 3rd and 4th range. １ and the second quality value Q ２ There appears to be a significant drop in quality between

[0038] On the other hand, when comparing the values ​​between the nodes in the corrected optical signal quality value D3 shown in FIG. 5C, the quality value Q ４Ｃ is the third quality value Q ３Ｃ Therefore, an abnormality is predicted to occur in the section between the third node and the fourth node.

[0039] That is, variations may occur in the optical signal quality measurement value D1 measured at each node position due to the influence of the characteristics of the terminals 21, 22 connected to the transmitting end and receiving end, respectively, of the optical communication relay network 10, and errors may occur when identifying the abnormality-occurring section. However, when the determination is based on the corrected optical signal quality value D3 calculated using the optical signal quality measurement value D1 and an appropriate reference value D2, it becomes possible to correctly identify the abnormality-occurring section even when arbitrary terminals 21, 22 are connected to the transmitting end and receiving end of the optical communication relay network 10.

[0040] <Processing Procedure of Optical Signal Quality Calculation Method> An example of the processing procedure when implementing the optical signal quality calculation method of the present invention is shown in Fig. 6. The processing procedure of Fig. 6 will be described below. As a preparation before a communications carrier managing optical communication relay network 10 starts providing communications services to users, in step S11, specific terminals 21R and 22R whose characteristics or specifications are known are connected to the transmitting end and receiving end, for example, as shown in Fig. 2. This operation can be performed manually by an operator, or by operating a predetermined switch that switches paths.

[0041] In fact, after an operator confirms in step S12 that normal communication is possible between the specific terminal 21R at the transmitting end and the specific terminal 22R at the receiving end via the optical communication relay network 10, the process proceeds to the next step S13.

[0042] 2, optical signal quality measurement monitors 171 to 175 connected to each of a plurality of relay node positions measure the quality value Q of the optical signal for each node position in step S13. Specifically, the optical signal quality measurement monitors 171 to 175 measure the OSNR value and the spectral width as the quality value Q of the optical signal.

[0043] The abnormal section estimation server 30 calculates the quality value Q of the optical signal for each node position measured in step S13 as a reference value Q ｎＲ The abnormal section estimation server 30 stores the information about the specific terminal 21R and the specific terminal 22R that are actually connected to the transmitting end and the receiving end, as well as route information. That is, the abnormal section estimation server 30 stores the manufacturer name, model, and transmission power range of the specific terminal 21R at the transmitting end, the manufacturer name, model, and OSNR tolerance of the specific terminal 22R at the receiving end, and information about the communication speed, modulation method, baud rate, and wavelength band common to the transmitting and receiving ends. The abnormal section estimation server 30 also stores route information that indicates the combination of each relay node on the route connecting the transmitting end and the receiving end.

[0044] The operator prepares in advance multiple types of specific terminals 21R, 22R of different manufacturers and models, and causes the abnormal section estimation server 30 to repeat the processes of steps S11 to S15 for each combination of multiple types of specific terminals 21R, 22R. This makes it possible to create a database such as the reference value table 70 shown in Fig. 4. Once the database creation is complete, the process proceeds from step S15 to S16.

[0045] When a communications carrier managing the optical communication relay network 10 starts providing communications services to each user, any terminals 21 and 22 are connected to the transmitting end and receiving end of the optical communication relay network 10, respectively, as shown in Fig. 1. The specifications of the optical communication relay network 10 of this embodiment allow the connection of any terminals 21 and 22. This makes it easy to interconnect optical communication networks between multiple communications carriers.

[0046] When the optical communication relay network 10 opens a communication service to a user, and while the communication service is being provided, the abnormal section estimation server 30 in Fig. 7, which manages the optical communication relay network 10, detects whether normal communication is possible between the terminals 21 and 22 currently connected to the transmitting end and the receiving end. If the abnormal section estimation server 30 detects that the communication state between the terminals 21 and 22 is NG, the process proceeds to step S18.

[0047] In step S18, the abnormal section estimation server 30 measures the optical signal quality at each relay node position in the optical communication relay network 10, for example, by using each of the optical signal quality measurement monitors 17-1 to 17-5 shown in FIG.

[0048] In step S19, the abnormal section estimation server 30 extracts from the database one pattern of combination of reference values ​​that is similar to the state of the measurement results in step S18. For example, if the reference value table 70 shown in Fig. 4 is held as the database, one pattern is selected from the multiple patterns P01, P02, P03, ..., and the data for that pattern is acquired.

[0049] The abnormal section estimation server 30 prioritizes patterns in which the route information matches, patterns in which the manufacturer names and model numbers of the terminals 21 and 22 connected to the transmitting end and receiving end match the specific terminals 21R and 22R used in each pattern, and patterns in which the conditions such as communication speed, modulation method, baud rate, and wavelength band are similar, and selects one appropriate pattern with the most similar conditions. For example, when pattern P01 is selected, the reference values ​​Q １Ｒ ~Q ５Ｒ As a result, 37.0 [dB], 34.5 [dB], 34.2 [dB], 33.5 [dB], and 31.8 [dB] are extracted from the reference value table 70 of FIG.

[0050] The abnormal section estimation server 30 extracts the reference value Q １Ｒ ~Q ５Ｒ Using the above, the quality value Q of each node position measured in step S18 is calculated. １ ~Q ５ That is, the corrected quality value Q is calculated using the above-mentioned formula (2). １Ｃ ~Q ５Ｃ Calculate.

[0051] The abnormal section estimation server 30 calculates the corrected quality value Q １Ｃ ~Q ５Ｃ In step S21, an abnormal section on the communication path is estimated based on the corrected optical signal quality value D3 shown in FIG. 5C. For example, when the corrected optical signal quality value D3 is obtained, the quality value Q of the third node position is calculated. ３Ｃ The quality value Q of the fourth node position from ４Ｃ Since the drop in the range to is larger than in the other sections, it can be determined that the section between the third and fourth sections is abnormal.

[0052] <Configuration of Optical Signal Quality Calculation Device> An example configuration of an optical signal quality calculation device of the present invention is shown in Fig. 7. The configuration of Fig. 7 will be described below. The communication system shown in Fig. 7 includes an abnormal section estimation server 30 having the functions of the optical signal quality calculation device of the present invention.

[0053] N relay nodes 23-1 to 23-N are arranged in the optical communication relay network 10, and adjacent relay nodes 23 are connected via optical fiber transmission lines 15. Each relay node has an optical signal relay unit 50. As shown in Fig. 7, each optical signal relay unit 50 has an optical signal branching unit 51, a wavelength selective switch 52, and an optical signal amplifier (Amp) 53 built in.

[0054] Furthermore, an optical signal quality measurement monitor 40 is connected to the optical signal repeater unit 50 of each repeater node 23. The optical signal quality measurement monitor 40 includes an optical signal quality measurement unit 41 and a measurement value transmission unit 42. The optical signal quality measurement unit 41 has a function of receiving an optical signal branched from the optical signal repeater unit 50 of the corresponding repeater node 23 and measuring the OSNR, spectral width, and the like as quality measurement values. The measurement value transmission unit 42 has a function of transmitting the quality measurement values ​​of the optical signal measured by the optical signal quality measurement unit 41 to the abnormal section estimation server 30 via communication.

[0055] The abnormal section estimation server 30 includes a GUI unit 31 , a reference value registration unit 32 , a reference value storage database 33 , a measurement value collection unit 34 , a reference value extraction unit 35 , a measurement value correction unit 36 ​​, and an abnormal section estimation unit 37 .

[0056] The GUI unit 31 of the abnormal section estimation server 30 includes a transmitting end / receiving end information input unit 31a, a display unit 31b, and a route information registration unit 31c. An administrator managing the optical communication relay network 10 can input necessary information while checking the contents displayed on the display unit 31b. The transmitting end / receiving end information input unit 31a can be used to input information on specific terminals 21R and 22R and any terminals 21 and 22 connected to the transmitting end and receiving end of the optical communication relay network 10, respectively. The route information registration unit 31c can be used to input information on routes connecting the transmitting end and receiving end for each pattern to be registered in the database. Note that the information input using the GUI unit 31 may be performed manually by the administrator or automatically. The measurement value collection unit 34 can periodically collect data on the results of measurements performed by the optical signal quality measurement monitors 40 connected to each relay node 23.

[0057] Before the communication service is opened to users, when known specific terminals 21R, 22R are connected to the transmitting end and receiving end of the optical communication relay network 10 to be managed and normal communication is being performed between the specific terminals 21R, 22R, the reference value registration unit 32 acquires optical signal quality measurement values ​​at each node position as reference values ​​from the measurement value collection unit 34. Then, the reference value registration unit 32 associates the reference value acquired for each node with the information on the specific terminals 21R, 22R at the transmitting end and receiving end input from the transmitting end / receiving end information input unit 31a, and the route information input from the route information registration unit 31c, and registers them as one pattern in the reference value storage database 33.

[0058] The reference value storage database 33 is a predetermined storage device, and can register information input from the reference value registration unit 32 as a database. With various types of specific terminals 21R, 22R connected to the optical communication relay network 10, a plurality of patterns of information can be registered in the reference value storage database 33 using the measurement value for each relay node 23 as a reference value. A plurality of patterns of reference values ​​with different routes can also be registered.

[0059] The reference value extraction unit 35 identifies an optimal pattern that is similar to the current connection environment of the transmitting end and receiving end based on the information input from the GUI unit 31 when or after the communication service is opened to the user, and extracts and obtains the reference value information of the corresponding pattern from the reference value storage database 33.

[0060] The measurement value corrector 36 corrects the measurement values ​​collected by the measurement value collector 34 from the optical signal quality monitors 40 of each relay node 23 when an abnormality occurs in communication between the terminals 21 and 22 while the terminals 21 and 22 are connected to the transmitting end and receiving end of the optical communication relay network 10. That is, the measurement values ​​for the currently connected terminals 21 and 22 are corrected by calculation using one pattern of reference values ​​extracted by the reference value extractor 35.

[0061] The abnormal section estimation unit 37 has an estimation function for identifying a section where an abnormality has occurred when an abnormality has occurred in communication between the terminal 21 and the terminal 22 while an arbitrary terminal 21 and an arbitrary terminal 22 are connected to the transmitting end and the receiving end of the optical communication relay network 10. That is, the abnormal section estimation unit 37 identifies a section where an abnormal change has appeared in the measurement value between adjacent nodes as an abnormal section based on a combination of corrected values ​​calculated by the measurement value correction unit 36, and outputs the determination result to the display unit 31b.

[0062] The functions of the GUI unit 31, the reference value registration unit 32, the measurement value collection unit 34, the reference value extraction unit 35, the measurement value correction unit 36, and the abnormal section estimation unit 37 can be realized, for example, as a program that can be executed by a computer on the abnormal section estimation server 30.

[0063] 8 is a diagram showing another example of the configuration of an optical signal quality calculation device of the present invention. In this embodiment, an optical signal repeater 50-1 has an optical signal splitter 51A inserted upstream of a wavelength selective switch 52 to split a signal, and transmits the split signal via a monitor 40A-1 to an abnormal section estimation server 30. The monitor 40A-1 includes an optical signal quality measurement unit 41A that measures the quality of the optical signal, and a measurement value transmission unit 42A that transmits the measurement value.

[0064] The optical signal repeater 50-1 further inserts an optical signal splitter 51B between the wavelength selective switch 52 and the optical signal amplifier 53 to split the signal, and transmits the split signal via the monitor 40B-1 to the abnormal section estimation server 30. The monitor 40B-1 includes an optical signal quality measurement unit 41B that measures the quality of the optical signal, and a measurement value transmission unit 42B that transmits the measurement value.

[0065] The optical signal repeater 50-1 further inserts an optical signal splitter 51C downstream of the optical signal amplifier 53 to split the signal, and transmits the split signal to the abnormal section estimation server 30 via the monitor 40C-1. The monitor 40C-1 includes an optical signal quality measurement unit 41C that measures the quality of the optical signal, and a measurement value transmission unit 42C that transmits the measurement value.

[0066] As a result, the abnormal section estimation server 30, which is the optical signal quality calculation device of the present invention, can be used to narrow down the abnormal location to a more detailed location inside the optical signal repeater unit 50-1.

[0067] The optical signal quality calculation device of the present invention can be used in situations other than when a communication abnormality occurs. That is, since it is possible to grasp the correct measured value of the optical signal quality at each relay node position, regardless of the type of equipment at the transmitting end or receiving end, the signal speed, the modulation method, etc., the optical signal quality calculation device can also be used to check for quality degradation trends and the presence of signs of failure in an APN relay section currently in operation.

[0068] <Features of Optical Signal Quality Calculation Method and Optical Signal Quality Calculation Device> The following [1] to [4] list the features of the optical signal quality calculation method and optical signal quality calculation device for an optical communication network of the present invention. [1] A method for calculating optical signal quality in an optical communication network, comprising: (10, 60) in a state where a specific transmitting end device (specific terminal 21R) and a specific receiving end device (specific terminal 22R) having known characteristics are connected; under conditions where normal communication is possible between the transmitting end device and the receiving end device via the optical communication relay network, performing a first optical signal quality measurement for each of a plurality of relay nodes on the optical communication relay network, and retaining the results as a plurality of sets of reference values ​​for each combination of the transmitting end device and the receiving end device and for each route (S14); (S18) in a state where an arbitrary transmitting end device (terminal 21) and an arbitrary receiving end device (terminal 22) are connected to the optical communication relay network; (S19) extracting a specific case in which the route, transmitting end device, and receiving end device in the second optical signal quality measurement are similar from the plurality of sets of reference values; and (S20) correcting the result of the second optical signal quality measurement using the reference value corresponding to the specific case.

[0069] According to the method for calculating optical signal quality in an optical communication network according to the procedure [1] above, even when various devices are connected to the transmitting end device and the receiving end device of the optical communication relay network depending on the situation, it is possible to extract a reference value for a specific case in which the situation is similar from among multiple cases, and obtain a corrected measurement value of the optical signal quality using the extracted reference value. Therefore, even in a situation where, for example, the signal speed or modulation method of the optical signal changes, or the devices of the transmitting end device or the receiving end device are changed, it is possible to grasp a more accurate optical signal quality value for each relay node.

[0070] [2] The optical signal quality calculation method for an optical communication network according to the above [1], wherein a result of the second optical signal quality measurement after correction is used to estimate at least an abnormality occurrence section in the optical communication relay network (S21).

[0071] According to the method for calculating optical signal quality in an optical communication network according to the procedure [2] above, estimation is performed based on the result of the second optical signal quality measurement after correction, so that it is possible to correctly estimate the section of the network where an abnormality has occurred, even in a situation where, for example, the signal speed or modulation method of the optical signal changes, or the equipment of the transmitting end device or the receiving end device is changed.

[0072] [3] A reference value storage unit (reference value storage database 33, reference value table 70) that stores the results of a first optical signal quality measurement (step S13) performed for each of a plurality of relay nodes (23) on the optical communication relay network under a condition in which a specific transmitting end device (specific terminal 21R) and a specific receiving end device (specific terminal 22R) having known characteristics are connected to the optical communication relay network and normal communication can be performed between the transmitting end device and the receiving end device via the optical communication relay network, as a plurality of sets of reference values ​​for each combination of the transmitting end device and the receiving end device and for each route; and a measurement value collection unit (34) that performs a second optical signal quality measurement (step S18) for each of a plurality of relay nodes (23) on the optical communication relay network and collects measurement values ​​when an arbitrary transmitting end device (terminal 21) and an arbitrary receiving end device (terminal 22) are connected to the optical communication relay network. an optical signal quality calculation device (abnormal section estimation server 30) for an optical communication network, comprising: a measurement value correction unit (36) that extracts a specific case in which the path, transmitting end device, and receiving end device in the second optical signal quality measurement are similar from the multiple sets of reference values ​​(reference value extraction unit 35), and corrects the result of the second optical signal quality measurement using the reference value corresponding to the specific case.

[0073] According to the optical signal quality calculation device for an optical communication network having the configuration described in [3] above, even when various devices are connected to the transmitting end device and the receiving end device of the optical communication relay network depending on the situation, it is possible to extract a reference value for a specific case in which the situation is similar from among multiple cases, and obtain a corrected measurement value of the optical signal quality using the extracted reference value. Therefore, even in a situation where, for example, the signal speed or modulation method of the optical signal changes, or the devices of the transmitting end device or the receiving end device are changed, it is possible to grasp a more accurate optical signal quality value for each relay node.

[0074] [4] The reference value holding unit holds at least a first parameter (manufacturer name, model number, transmission power range, etc.) representing the attributes of the transmitting end device (specific terminal 21R), a second parameter (manufacturer name, model number, OSNR tolerance, etc.) representing the attributes of the receiving end device (specific terminal 22R), and a third parameter (communication speed, modulation method, baud rate, wavelength band, etc.) representing communication attributes common to the transmitting end device and the receiving end device, in a state corresponding to a reference value. An optical signal quality calculation device (abnormal section estimation server 30) of an optical communication network described in [3] above.

[0075] According to the optical signal quality calculation device for an optical communication network having the configuration described in [4] above, it is possible to manage multiple sets of reference values ​​by distinguishing between attributes specific to the device of the transmitting end device, attributes specific to the device of the receiving end device, and communication attributes common to the transmitting end device and the receiving end device as different cases. Therefore, it becomes easy to correctly select a specific case in which the situation when the reference value is measured is similar to the situation when any device is connected to the transmitting end device and the receiving end device of the optical communication relay network.

[0076] 10, 60 Optical communication relay network 15 Optical fiber transmission path 17, 17-1, 17-2, 17-3, 17-4, 17-5 Optical signal quality measurement monitor 21, 22 Terminal 21R, 22R Specific terminal 30 Abnormal section estimation server (optical signal quality calculation device) 31 GUI unit 31a Transmitting end / receiving end information input unit 31b Display unit 31c Route information registration unit 32 Reference value registration unit 33 Reference value storage database 34 Measurement value collection unit 35 Reference value extraction unit 36 ​​Measurement value correction unit 37 Abnormal section estimation unit 40, 40-1, 40-N Optical signal quality measurement monitor 41 Optical signal quality measurement unit 42 Measurement value transmission unit 50, 50-1, 50-N Optical signal relay unit 51 Optical signal branching unit 52 Wavelength selective switch 53 Optical signal amplifier D1 Optical signal quality measurement value D2 Reference value D3 Optical signal quality value 23-1, 23-2, 23-3, 23-4, 23-5 Relay nodes P1, P2, P3 Pattern 70 Reference value table

Claims

1. A method for calculating optical signal quality in an optical communication network, comprising: performing a first optical signal quality measurement for each of a plurality of relay nodes on an optical communication network in a state in which a specific transmitting end device and a specific receiving end device having known characteristics are connected, under conditions in which normal communication can be performed between the transmitting end device and the receiving end device via the optical communication network; retaining the results of the first optical signal quality measurement for each combination of the transmitting end device and the receiving end device and for each route as multiple sets of reference values; performing a second optical signal quality measurement for each of a plurality of relay nodes on the optical communication network in a state in which an arbitrary transmitting end device and an arbitrary receiving end device are connected to the optical communication network; extracting from the multiple sets of reference values ​​a specific case in which the route, transmitting end device, and receiving end device in the second optical signal quality measurement are similar; and correcting the result of the second optical signal quality measurement using the reference value corresponding to the specific case.

2. The method for calculating optical signal quality in an optical communication network according to claim 1, further comprising: estimating at least an abnormality-occurring section in said optical communication relay network using the result of said second optical signal quality measurement after correction.

3. An optical signal quality calculation device for an optical communication network, comprising: a reference value storage unit that stores the results of a first optical signal quality measurement performed on each of a plurality of relay nodes on the optical communication relay network as multiple sets of reference values ​​for each combination of the transmitting end device and the receiving end device and for each route, under conditions in which a specific transmitting end device and a specific receiving end device having known characteristics are connected to the optical communication relay network and normal communication can be performed between the transmitting end device and the receiving end device via the optical communication relay network; a measurement value collection unit that performs a second optical signal quality measurement on each of a plurality of relay nodes on the optical communication relay network and collects measurement values, under a condition in which an arbitrary transmitting end device and an arbitrary receiving end device are connected to the optical communication relay network; and a measurement value correction unit that extracts from the multiple sets of reference values ​​a specific case in which the route, transmitting end device, and receiving end device in the second optical signal quality measurement are similar, and corrects the result of the second optical signal quality measurement using the reference value corresponding to the specific case.

4. An optical signal quality calculation device for an optical communication network as described in claim 3, wherein the reference value holding unit holds at least a first parameter representing an attribute of a transmitting end device, a second parameter representing an attribute of a receiving end device, and a third parameter representing a communication attribute common to the transmitting end device and the receiving end device, in correspondence with each reference value.

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