Estimation device and estimation method

Abstract

An estimation device 10 comprises: a storage unit 13 that retains a wavelength-dependency reference; an input unit 11 that inputs an OSNR measurement value measured in a vacant channel different from an investigation target channel; and an estimation unit 12 that estimates the OSNR of the investigation target channel from the deviation of the OSNR measurement value in the vacant channel from a reference value, and a reference value of the investigation target channel. The estimation device 10: inputs an OSNRWSS obtained by measuring an optical power PON acquired when pseudo light is on and a noise optical power POFF acquired when the pseudo light is off; corrects the OSNRWSS by using a WSS extinction ratio; and estimates the optical signal-to-noise ratio of the investigation target channel.

Description

Estimation Device and Estimation Method 【0001】 The present disclosure relates to an estimation device and an estimation method. 【0002】 An optical transmission network is an infrastructure that supports various services and applications. Management of communication quality plays an important role in improving the reliability of the network. 【0003】 As a representative index for evaluating the communication quality of an optical transmission network, there is an Optical Signal to Noise Ratio (OSNR) used to evaluate the signal quality. In Non-Patent Document 1, an OSNR monitor is arranged at each relay point of the optical transmission network, enabling monitoring and grasping of the quality at each relay point. 【0004】 Hiroshi Shibata, et al., "A Study on Improving the Estimation Accuracy of Quality Abnormal Sections in Optical Communication Relay Networks", 2024 IEICE General Conference, B-6-55 【0005】 In order to obtain the OSNR in the in-service state without interrupting the optical communication service, it is necessary to branch the optical signal and input a part of it to the OSNR monitor. This branching may reduce the power of the signal and have an adverse effect on the communication quality. 【0006】 The present disclosure has been made in view of the above, and an object thereof is to estimate the OSNR without affecting the communication quality. 【0007】 An estimation device according to an aspect of the present disclosure includes a storage unit that holds a reference value of the optical signal-to-noise ratio for each channel in a relay section, an input unit that inputs a measured value of the optical signal-to-noise ratio measured in an empty channel different from the channel to be investigated, and an estimation unit that estimates the optical signal-to-noise ratio of the channel to be investigated from the deviation of the measured value in the empty channel from the reference value and the reference value of the channel to be investigated. 【0008】 According to the present disclosure, the OSNR can be estimated without affecting the communication quality. 【0009】Figure 1 shows an example of the configuration of the estimation device and the optical communication relay network. Figure 2 shows an example of a wavelength-dependent reference. Figure 3 is a diagram illustrating how to obtain the estimated value using the wavelength-dependent reference. Figure 4 is a flowchart illustrating an example of the OSNR estimation process flow. Figure 5 shows an example of an optical communication relay network composed of multiple optical transmission devices with different wavelength-dependent tendencies. Figure 6 is a flowchart illustrating an example of the OSNR estimation process flow. Figure 7 shows an example of a reference model composed only of relay nodes. Figure 8 shows an example of a reference model composed only of amplifiers. Figure 9 shows an example of a wavelength-dependent reference for a relay node obtained using the reference model in Figure 7. Figure 10 shows an example of a wavelength-dependent reference for an amplifier obtained using the reference model in Figure 8. Figure 11 shows an example of a reference model with amplifiers placed between relay nodes. Figure 12 shows an example of a wavelength-dependent reference obtained using the reference model in Figure 11. Figure 13 shows the measurement of the OSNR of the optical communication relay network in Figure 5. Figure 14 is a diagram illustrating how to obtain the estimated value using the wavelength-dependent reference of the relay section obtained by synthesis. Figure 15 is a flowchart showing an example of the process flow for correcting measured values. Figure 16 shows an example of the configuration of a communication system for measuring the WSS extinction ratio. Figure 17 shows a measured spectral image at OSA. Figure 18 shows an example of OSNR before correction. Figure 19 shows an example of OSNR after correction. Figure 20 shows an example of the hardware configuration of the estimation device. 【0010】 [Optical Communication Relay Network] Referring to Figure 1, an example of the configuration of an optical communication relay network and an example of the configuration of the estimation device 10 will be described. 【0011】 In an optical communication relay network, an optical wavelength path is established between an optical transmitter 110 and an optical receiver 120 via a relay node 130. Each device is connected by an optical fiber 100. By using wavelength division multiplexing (WDM), it becomes possible to transmit large amounts of data using multiple wavelengths (also called channels) on a single optical fiber. 【0012】For example, the optical transmitter 110 and the optical receiver 120 each function as an All Photonics Network - Transceiver (APN-T) and are transceivers that constitute the endpoints of the optical wavelength path. 【0013】 For example, relay node 130 functions as an All Photonics Network - Gateway (APN-G) and is a Reconfigurable Optical Add / Drop Multiplexer (ROADM) that relays optical wavelength paths. Relay node 130 includes a Pseudo Wave (PW) light source 131 that emits pseudo light and a monitor 132 that measures the optical power of the pseudo light. The PW light source 131 and monitor 132 serve the channel (wavelength λ) in service. S ) rather than an empty channel (wavelength λ T The OSNR value of the relay section is measured using the ON / OFF method. The ON / OFF method is a method of calculating the OSNR by measuring the sum of the signal optical power and noise power when the optical signal is ON, and measuring the optical power of the noise component when the optical signal is OFF. Wavelength λ S and different wavelengths λ T Since it uses an optical signal, the OSNR can be measured without affecting the channel in service. The pseudo-light function of ROADM can be used for the PW light source 131 and the monitor 132. Alternatively, an OSNR monitor used in Non-Patent Document 1, which converts the optical signal to an electrical signal, measures the high-frequency component power of the electrical signal, and converts it to an OSNR value, may be used. 【0014】The OSNR value measured using an unused channel differs from the OSNR value of a channel in service due to wavelength dependence. Therefore, the estimation device 10 estimates the OSNR of the channel in service based on the deviation of the OSNR measurement value on the unused channel from the wavelength-dependent reference. Wavelength dependence refers to the phenomenon where the gain and noise amount of the optical signal power differ depending on the wavelength. When multiple optical signals of different wavelengths are transmitted simultaneously through a single optical fiber, each wavelength may be affected by different characteristics from the optical transmission equipment on the transmission path. The wavelength-dependent reference is a reference value (also called a normal value or reference value) of OSNR for each wavelength in an optical communication relay network, and is acquired in advance in the experimental environment. 【0015】 [Estimation Device] The estimation device 10 shown in Figure 1 comprises an input unit 11, an estimation unit 12, and a storage unit 13. The estimation device 10 receives OSNR values ​​measured using idle channels in an optical communication relay network in actual operation (hereinafter also referred to as the commercial environment), and estimates the OSNR of a channel in service (hereinafter also referred to as the channel under investigation) by considering the difference in OSNR between channels due to wavelength dependence. 【0016】 The input unit 11 receives the OSNR value measured on an available channel in the relay section of the optical communication relay network. 【0017】 The estimation unit 12 estimates the OSNR of the channel under investigation by considering the wavelength-dependent reference held by the memory unit 13 and the deviation (also called the degree of degradation) of the OSNR measurement value in the unused channel from the reference value. 【0018】The memory unit 13 holds the wavelength-dependent reference. In advance, the OSNR is measured for each channel (wavelength) and used as the wavelength-dependent reference of the relay node 130. For example, in creating the wavelength-dependent reference, in FIG. 1, using the PW light source 131 and the monitor 132, the OSNR for each channel is measured by the ON / OFF method. The OSNR may also be measured using the optical signal from the optical transmission device 110. The memory unit 13 holds the OSNR value (hereinafter referred to as the reference value) measured for each channel as the wavelength-dependent reference. The reference value may be measured using an optical communication relay network in an experimental environment prepared separately from the commercial environment. The optical transmission devices such as the relay node 130 used for measuring the reference value are used in a normal state while operating normally. 【0019】 FIG. 2 shows an example of the wavelength-dependent reference. In the example of FIG. 2, the OSNR measurement values obtained by measuring nine channels between 1530 nm and 1565 nm are shown. Note that in FIG. 2, for simplicity of explanation, the wavelength-dependent reference in the case where the graph is a straight line is shown. 【0020】 The reference value is a standard of the OSNR in a normal state. When an abnormality occurs in an optical transmission device or the like, the OSNR value deteriorates compared to the reference value. The estimation device 10 estimates the OSNR of the investigation target channel from the degree of deterioration of the OSNR measurement value in the free channel from the reference value. 【0021】 Referring to FIG. 3, an example of estimating the OSNR of the investigation target channel using the wavelength-dependent reference will be described. The calculation of the estimated value OSNR(λ T ) from the measured value OSNR(λ T ) in the free channel (wavelength λ S ) to the estimated value OSNR(λ S ) in the investigation target channel (wavelength λ 【0022】 [[ID=2i]] 【0023】 ] Here, OSNR ref (λ S ) is the reference value at wavelength λ S , OSNR ref(λ T ) is wavelength λ T This is the reference value. For example, the reference value and the measured value are, respectively, OSNR ref (λ S ) = 19.3dB, OSNR ref (λ T ) = 19.8dB, OSNR(λ T If ) = 19.5 dB, the estimated OSNR(λ S ) = 19.0 dB. Note that the calculation is performed using the true value, not the dB value. The same applies to subsequent calculations. 【0024】 [OSNR Estimation Process] An example of the OSNR estimation process will be explained by referring to the flowchart in Figure 4. 【0025】 In step S1, the wavelength-dependent reference of the OSNR of the relay node 130 is measured. For example, in an experimental environment, an optical communication relay network is constructed using relay nodes 130 equivalent to those in a commercial environment, and the OSNR is measured for each wavelength using the ON / OFF method with the PW light source 131 and monitor 132 provided by the relay node 130. The measurement results of the OSNR for each wavelength are stored in the estimation device 10 as a wavelength-dependent reference. Alternatively, the wavelength-dependent reference of the OSNR may be measured using an Optical Spectrum Analyzer (OSA). 【0026】 Step S1 is a preliminary step, which is performed at least once to store the wavelength-dependent reference in the estimation device 10. After the preliminary step, the following steps S2 and S3 are continuously performed in the commercial environment. 【0027】 In step S2, the OSNR value of an available channel, rather than a channel in service, is determined using the ON / OFF method in the commercial environment. The OSNR value of the available channel is measured using the PW light source 131 and monitor 132 provided by the relay node 130 in the commercial environment. 【0028】In step S3, the estimation device 10 estimates the OSNR value of the channel under investigation from the OSNR measurement value. Specifically, the estimation device 10 receives the OSNR measurement value as input, reads out the reference value of the available channel and the reference value of the channel under investigation, and estimates the OSNR of the channel under investigation using the calculation formula described above. 【0029】 Since the OSNR value is measured on an unused channel, it is unnecessary to split the optical signal of a channel in service, and as a result, the OSNR of a channel in service can be estimated without affecting quality. 【0030】 [Application to Complex Network Configurations] In the optical communication relay network shown in Figure 5, an optical wavelength path is constructed between the optical transmitter 110 and the optical receiver 120 via four relay nodes 130 and three amplifiers 140. For example, the amplifiers 140 function as All Photonics Network Interchange (APN-I) and are In-Line Amplifiers (ILAs) that amplify optical signals. ROADMs and ILAs have different built-in amplifiers, which can result in different wavelength-dependent characteristics. 【0031】 To create a wavelength-dependent reference, it is difficult to construct a relay network with the same configuration as the complex network configuration shown in Figure 5, which includes numerous optical transmitters, in an experimental environment. 【0032】 In this embodiment, a wavelength-dependent reference for an optical communication relay network of any network configuration is created by measuring reference values ​​with a simple configuration and synthesizing the measured reference values. 【0033】 Referring to the flowchart in Figure 6, an example of OSNR estimation processing in a complex network configuration will be explained. 【0034】In step S11, a simple optical communication relay network is constructed for each optical transmission device (e.g., ROADM or ILA), and a reference value is measured for each optical transmission device. Figure 7 shows an example of a reference model consisting only of relay nodes 130, and Figure 8 shows an example of a reference model consisting only of amplifiers 140. In step S11, an optical communication relay network is constructed in the experimental environment with the respective configurations of the reference models in Figures 7 and 8, and the reference values ​​of the relay nodes 130 and amplifiers 140 are measured. Figure 9 shows an example of the wavelength-dependent reference of the relay node 130 obtained using the reference model in Figure 7, and Figure 10 shows an example of the wavelength-dependent reference of the amplifier 140 obtained using the reference model in Figure 8. 【0035】 If the amplifier 140 does not have an OSNR measurement function, an optical communication relay network is constructed with the amplifier 140 placed between relay nodes 130 capable of measuring OSNR, as shown in Figure 11, and a reference value including the relay nodes 130 and the amplifier 140 is measured. Figure 12 shows an example of a wavelength-dependent reference for a configuration including the relay nodes 130 and the amplifier 140 obtained using the reference model in Figure 11. 【0036】 By subtracting the wavelength-dependent reference obtained for a configuration including only the relay node 130 (Figure 9) from the wavelength-dependent reference obtained for a configuration including the relay node 130 and the amplifier 140 (Figure 12), the wavelength-dependent reference for a configuration including only the amplifier 140 (Figure 10) can be obtained. Wavelength-dependent reference OSNR for amplifier 140 only ILA (λ) is the wavelength-dependent reference OSNR of a configuration including relay node 130 and amplifier 140. ROADM+ILA (λ) and the wavelength-dependent reference OSNR of relay node 130 ROADM Using (λ), it can be calculated using the following formula. 【0037】 【0038】 The wavelength-dependent reference for each optical transmission device is stored in the estimation device 10. 【0039】In step S12, the estimation device 10 synthesizes and creates a wavelength-dependent reference for an optical communication relay network with an arbitrary network configuration. For example, the estimation device 10 takes the number of optical transmission devices in the optical communication relay network as input, and synthesizes a wavelength-dependent reference for each optical transmission device according to the number of optical transmission devices to create a total wavelength-dependent reference for the optical communication relay network. 【0040】 SNR -1 Since it is additive, the total wavelength-dependent reference OSNR of a relay section equipped with M relay nodes 130 and N amplifiers 140 TOTALref (λ) can be found using the following formula. 【0041】 【0042】 Note that the wavelength-dependent reference obtained using the reference model in Figure 7 is the wavelength-dependent reference for two relay nodes 130, so the number of relay nodes 130 M is divided by 2. 【0043】 The optical communication relay network shown in Figure 5 has four relay nodes 130 and three amplifiers 140 in the relay section. Therefore, with M=4 for the number of relay nodes 130 and N=3 for the number of amplifiers 140, the wavelength-dependent reference for the relay section in Figure 5 can be calculated. 【0044】 Steps S11 and S12 are preliminary steps, which are performed at least once to store the wavelength-dependent reference for the relay section in the estimation device 10. After the preliminary steps, the subsequent steps S21 and S31 are carried out continuously in the commercial environment. 【0045】 In step S21, the OSNR value is measured in an empty channel, similar to step S2 in Figure 4. For example, as shown in Figure 13, an empty channel (wavelength λ T At the relay node 130 to which the optical transmitter 110 is connected, pseudo-light is emitted from the PW light source 131, and the optical power is measured by the monitor 132 at the relay node 130 to which the optical receiver 120 is connected, and the OSNR value of the relay section is measured. 【0046】In step S31, the estimation device 10 estimates the OSNR value of the channel under investigation from the OSNR measurement value. This differs from step S3 in Figure 4 in that it uses a wavelength-dependent reference obtained by synthesizing the wavelength-dependent references for each optical transmission device. The estimation device 10 receives the OSNR measurement value as input and the reference value OSNR of the available channel. TOTALref (λ T ) and the reference value OSNR of the channel under investigation TOTALref (λ S Read out the OSNR(λ) of the channel under investigation using the following formula. S We estimate ). 【0047】 【0048】 Figure 14 shows the wavelength-dependent reference of the relay section obtained by synthesis, and how the OSNR of the target channel is estimated using the wavelength-dependent reference of the relay section. Measured OSNR (λ) on an empty channel. T )=13.5dB, wavelength λ T Reference value OSNR TOTALref (λ T )=13.95dB, wavelength λ S Reference value OSNR TOTALref (λ S If λ = 13.64 dB, then the estimated OSNR of the channel under investigation is OSNR(λ S ) = 13.2 dB. 【0049】[Correction by WSS extinction ratio] The PW light source 131 in the relay node 130 is a light source common to all wavelengths. Therefore, in the ON / OFF method of the unused channel described above, instead of turning off the emission of light from the PW light source 131, the Wavelength Select Switch (WSS) installed downstream of the PW light source 131 blocks (filters) the wavelength components corresponding to the unused channel, thereby achieving a pseudo-light power-off state. The WSS has the function of receiving wavelength-multiplexed optical signals in the relay node 130 and passing or branching arbitrary wavelengths to arbitrary paths. The WSS filters the wavelength-multiplexed optical signals by setting a passband, allowing only the necessary optical signals to pass through. 【0050】 However, the WSS's filtering function cannot completely remove false light, allowing some stray light (e.g., around -33dB) to pass through. Therefore, in low-noise, high-quality environments (for example, environments with an OSNR of 30dB or higher, such as short distances or single span sections), errors occur in noise measurements when the WSS is OFF, reducing the accuracy of OSNR measurements. 【0051】 P S , noise light power P N Therefore, if stray light is transmitted, the light power P when the pseudo-light is ON. ON and light power P when simulated light is OFF OFF It can be expressed by the following equation. 【0052】 【0053】 Here, w is the percentage of light leakage when pseudo-light is blocked by WSS (hereinafter referred to as the WSS extinction ratio). 【0054】 OSNR measurement results using the simulated light ON / OFF method WSS P ON ,P OFF When expressed in this way, it becomes the following equation, which does not result in an accurate OSNR value. 【0055】 【0056】 Therefore, in this embodiment, the OSNR is measured using the ON / OFF method of pseudo-light with the WSS extinction ratio.WSS This corrects the OSNR value to a more accurate value. 【0057】 The WSS extinction ratio w is defined by the following equation. 【0058】 【0059】 WSS extinction ratio w is the accurate OSNR OSA OSNR measured using the pseudo-light ON / OFF method. WSS It is calculated using the relative error. Accurate OSNR OSA As a reference value, the OSA measurement value obtained by using OSNR measuring equipment and configuring the device can be used. For accurate OSNR values, values ​​measured by other methods may also be used. 【0060】 OSNR measured using the pseudo-light ON / OFF method WSS Correct it using the following formula, and the corrected OSNR corr We seek. 【0061】 【0062】 Referring to the flowchart in Figure 15, an example of the process flow for correcting measurements obtained using the ON / OFF method will be explained. 【0063】 In step S51, the wavelength-dependent reference of the OSNR of the relay node 130 is measured, similar to step S1 in Figure 4. 【0064】 In step S52, the WSS extinction ratio of the relay node 130 that emits false light is measured. The WSS extinction ratio may be measured in an experimental environment or a commercial environment. The WSS extinction ratio may also be measured when measuring the wavelength-dependent reference. Details of the measurement of the WSS extinction ratio will be described later. Note that the WSS extinction ratio may also be determined from the product specifications of the WSS module. 【0065】 Steps S51 and S52 are preparatory steps, which are performed at least once to store the wavelength-dependent reference and WSS extinction ratio in the estimation device 10. After the preparatory steps, the following steps S53 to S55 are continuously performed in the commercial environment. 【0066】In step S53, similar to step S2 in Figure 4, the OSNR value of an empty channel is measured in a commercial environment using the pseudo-light ON / OFF method. Specifically, pseudo-light is inserted into an empty channel different from the channel under investigation, and the optical power P when the pseudo-light is ON is measured. ON In addition to measuring the noise optical power P after blocking and removing false light with WSS, OFF Measure the light power P when the simulated light is ON. ON and noise light power P OFF OSNR for available channels WSS We will find this OSNR. WSS This includes the effects of stray light. 【0067】 In step S54, the estimation device 10 uses the WSS extinction ratio to determine the OSNR WSS Correct it. 【0068】 In step S55, the estimation device 10 estimates the OSNR value of the target channel from the OSNR measurement value, similar to step S3 in Figure 4. Step S3 in Figure 4 refers to the corrected OSNR as the OSNR measurement value. corr The difference lies in the use of [a specific term / method]. 【0069】 Some ROADMs have a function to adjust the power gain for each wavelength to prevent differences in OSNR due to wavelength dependence. In such ROADMs, steps S51 and S55 are unnecessary. 【0070】 Next, referring to Figure 16, an example of WSS extinction ratio measurement will be explained. 【0071】 In the optical communication relay network shown in Figure 16, relay nodes 130 are connected by optical fibers 100. An optical transmitter 110 is connected to a relay node 130 equipped with a PW light source 131 that emits pseudo-light, and an OSA 200 is connected to a relay node 130 equipped with a monitor 132 that measures the optical power of the pseudo-light. A WSS 133 that switches the ON / OFF state of the pseudo-light is placed downstream of the PW light source 131. The optical communication relay network shown in Figure 16 may be constructed in an experimental environment or a commercial environment. When constructing an optical communication relay network in an experimental environment, it is advisable to use the same relay nodes 130 as in a commercial environment. 【0072】 Accurate OSNR OSA In the measurement, the optical transmitter 110 provides an accurate OSNR OSA Measurement channel (wavelength λ) S The signal light from the ) is incident on the relay node 130 and received by the OSA 200. As shown in the measurement spectrum image of the OSA in Figure 17, either a narrowband laser beam is incident or the grid width is made several times wider than the signal width. The grid width is the wavelength interval between adjacent channels. The OSA 200 has a signal peak power P S +P N and the noise floor level P on both sides of the signal peak N Measure the optical power P of the signal light. S and noise light power P N From OSNR OSA To determine this, Figure 17 shows the measured spectral image when WSS leakage light is included, indicated by a dashed line. When the pseudo-light is OFF, the noise light power P N Light power of leaking light wP S This will be added. 【0073】 OSNR using the ON / OFF method WSS In the measurement, with the simulated light turned ON, the optical power P when the simulated light is ON was measured. ON The optical power P was measured with the pseudo-light turned OFF by blocking it with WSS. OFF The optical power P obtained from the measurement when the pseudo-light is ON is measured. ON and light power P when simulated light is OFF OFF From OSNR WSS We seek. 【0074】 According to the above formula, OSNR OSA OSNR for WSS The relative error is calculated and used as the WSS extinction ratio. 【0075】 Next, I will explain an example of the effects of the correction. 【0076】 Figure 18 shows the OSNR before correction. WSS This shows the correct OSNR on the horizontal axis and the OSNR on the vertical axis. WSS The straight line in the figure represents OSNR. WSSThis shows the ideal relationship when it is equal to the correct OSNR. WSS An error occurs. For example, in the case where the OSNR is around 30dB, the OSNR WSS This results in an error of approximately 1 dB or more compared to the correct value, and in cases where the OSNR is around 33 dB, an error of approximately 3 dB occurs. 【0077】 Figure 19 shows the corrected OSNR. corr This shows the correct OSNR on the horizontal axis and the OSNR on the vertical axis. corr The correction was applied, eliminating errors in the high OSNR range. 【0078】 OSNR using the ON / OFF method of simulated light to determine the WSS extinction ratio WSS Measurements should be performed on an optical transmission line with a high OSNR (e.g., 30 dB or higher). Alternatively, optical transmission lines with different OSNRs can be constructed, and the WSS extinction ratio can be determined for each OSNR in the high OSNR region. Note that leakage light varies from ROADM to ROADM, and to obtain a more accurate OSNR, it is necessary to investigate the WSS extinction ratio for all ROADMs using the PW light source 131 using the ON / OFF method. 【0079】 As described above, the estimation device 10 of this embodiment includes a storage unit 13 that holds a wavelength-dependent reference, an input unit 11 that inputs OSNR measurement values ​​measured on an unused channel other than the channel under investigation, and an estimation unit 12 that estimates the OSNR of the channel under investigation from the deviation of the OSNR measurement value on the unused channel from the reference value and the reference value of the channel under investigation. This makes it possible to estimate the OSNR of the channel under investigation without affecting the communication quality of the channel under investigation. 【0080】 According to this embodiment, by measuring a wavelength-dependent reference for each optical transmission device and synthesizing the wavelength-dependent references for each optical transmission device located in the relay section to create a reference value for the channel under investigation, it is possible to create a wavelength-dependent reference for an optical communication relay network of any network configuration in an experimental environment without constructing a network configuration equivalent to that of a commercial environment. 【0081】 The estimation device 10 of this embodiment measures the optical power P during pseudo light ON inserted into an empty channel ON and the noise optical power P during pseudo light OFF OFF to obtain the OSNR WSS as input, corrects the OSNR WSS with the WSS extinction ratio, and estimates the optical signal-to-noise ratio of the investigation target channel. Thereby, the ONSR can be estimated more accurately. 【0082】 For the above-described estimation device 10, 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. 15 can be used. In this computer system, the estimation device 10 is realized by the CPU 901 executing a predetermined program loaded on the memory 902. This program can be recorded on a computer-readable non-temporary recording medium such as a magnetic disk, an optical disk, or a semiconductor memory, or can be distributed via a network. 【0083】The functionality of each element of this disclosure may be implemented by any or a combination thereof, namely, general-purpose processors, special-purpose processors, integrated circuits, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), general-purpose circuits, or circuits or processing circuits that combine these. These circuits or processing circuits may also be composed of programs stored in one or more memories, or may be composed in other ways to perform such functions. A processor is considered a circuit or processing circuit because it includes transistors and other circuits. A processor may be a programmed processor that executes programs stored in memory. In this disclosure, a circuit, unit, or means is hardware that performs the enumerated functions, or hardware programmed to perform the enumerated functions. Hardware may be any hardware of this disclosure that is programmed or configured to perform the enumerated functions. 【0084】 Memory stores computer programs, including computer instructions. These computer instructions provide logic and routines that enable hardware (e.g., circuits or processing circuits) to perform the methods of this disclosure. This computer program can be implemented in common forms, such as computer-readable storage media, computer program products, memory devices, recording media such as CD-ROMs and DVDs, and / or memory in ASICs and FPGAs. 【0085】 This disclosure is not limited to the embodiments described above, and numerous modifications are possible within the scope of its essence. 【0086】10 Estimation device 11 Input unit 12 Estimation unit 13 Memory unit 100 Optical fiber 110 Optical transmitter 120 Optical receiver 130 Relay node 131 Pseudo Wave light source 132 Monitor 133 Wavelength Select Switch 140 Amplifier 200 Optical Spectrum Analyzer

Claims

1. An estimation device comprising: a storage unit that holds a reference value of the optical signal-to-noise ratio for each channel in the relay section of an optical signal; an input unit that inputs a measured value of the optical signal-to-noise ratio measured in an unused channel other than the channel under investigation; and an estimation unit that estimates the optical signal-to-noise ratio of the channel under investigation from the deviation of the measured value in the unused channel from the reference value and the reference value of the channel under investigation.

2. Estimation device according to claim 1, comprising measuring the optical signal-to-noise ratio for each channel for each optical transmission device, and synthesizing the optical signal-to-noise ratios for each optical transmission device arranged in the relay section to create the reference value.

3. Estimation device according to claim 1, wherein the input unit receives an optical signal-to-noise ratio obtained by measuring the optical power of a false light inserted into the empty channel and the noise optical power after blocking and removing the false light, and the estimation unit corrects the optical signal-to-noise ratio by the ratio of leaked light when the false light is blocked to estimate the optical signal-to-noise ratio of the channel under investigation.

4. Estimation device according to claim 3, wherein the percentage of leaked light when the false light is blocked is determined using the relative error of the optical signal-to-noise ratio obtained from the optical power of the false light and the noise optical power after the false light has been blocked and removed, relative to the accurate optical signal-to-noise ratio.

5. An estimation method comprising: obtaining a reference value for the optical signal-to-noise ratio for each channel in the relay section of an optical signal; measuring the optical signal-to-noise ratio in the relay section on an unused channel other than the channel under investigation; and estimating the optical signal-to-noise ratio of the channel under investigation from the deviation of the measured value on the unused channel from the reference value and the reference value of the channel under investigation.

6. An estimation method according to claim 5, comprising measuring the optical signal-to-noise ratio for each channel for each optical transmission device, and creating the reference value by synthesizing the optical signal-to-noise ratios for each optical transmission device arranged in the relay section.

7. An estimation method according to claim 5, comprising: inputting an optical signal-to-noise ratio obtained by measuring the optical power of a false light inserted into the empty channel and the noise optical power after blocking and removing the false light; and estimating the optical signal-to-noise ratio of the channel under investigation by correcting the optical signal-to-noise ratio with the rate of leakage light when the false light is blocked.

8. An estimation method according to claim 7, wherein the percentage of leaked light when the false light is blocked is determined using the relative error of the optical signal-to-noise ratio obtained from the optical power of the false light and the noise optical power after the false light has been blocked and removed, with respect to the accurate optical signal-to-noise ratio.

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