Estimation device and estimation method

Abstract

An estimation device 14 comprises: a measurement unit 141 that measures, for an optical transmitter and an optical receiver connected via a transmission path, a value of signal quality or transmission quality for each received optical power in the optical receiver; a first calculation unit 142 that calculates a penalty related to signal quality or transmission quality dependent on the received optical power by using a measured value of signal quality or transmission quality for each received optical power in the optical receiver; and a second calculation unit 143 that calculates, using the penalty related to signal quality or transmission quality dependent on the received optical power, a change amount of relationship between signal quality and transmission quality of the optical transmitter and the optical receiver that corresponds to a change in received optical power.

Description

Estimation device and estimation method

[0001] The present disclosure relates to an estimation device and an estimation method.

[0002] Estimating signal quality (e.g., Q-factor, Pre-FEC BER) and measuring transmission quality (e.g., GSNR) are essential technologies for designing, operating, and monitoring optical networks. To estimate signal quality and measure transmission quality with high accuracy, it is necessary to grasp the BER-OSNR characteristics of optical transceivers in a back-to-back configuration in which the optical transmitter and receiver are directly connected by optical fiber with a very short propagation distance.

[0003] For example, in a back-to-back configuration, the signal light from the optical transmitter and the optical noise from the optical noise generator are multiplexed by a multiplexer, and the optical noise level (OSNR) and signal quality (e.g., Pre-FEC BER) are measured when the multiplexed light is input to an optical receiver. If the measured values ​​are plotted on a graph with the optical noise level (transmission quality) on the horizontal axis and the signal quality on the vertical axis, the BER-OSNR characteristic is obtained, where the signal quality decreases as the optical noise level increases.

[0004] By utilizing this BER-OSNR characteristic, the signal quality of the received signal can be estimated from transmission quality measured or estimated in advance or calculated using a tool such as GNPy (see Non-Patent Document 1). Simply read the signal quality value corresponding to the calculated transmission quality value. Conversely, the transmission quality can be estimated from the signal quality measured by the optical transceiver (see Non-Patent Document 2). Simply read the transmission quality (optical noise amount) value corresponding to the measured signal quality value.

[0005] Vittorio Curri, “GNPy model of the physical layer for open and disaggregated optical networking [Invited]”, JOURNAL OF Optical Communications and Networking, Vol. 14, No. 6, June 2022, C92-C104Kaida Kaeval, and 8 others, “QoT assessment of the optical spectrum as a service in disaggregated network scenarios”, JOURNAL OF Optical Communications and Networking Networking, Vol.13, No.10, October 2021, E1-E12

[0006] BER-OSNR characteristics are measured by fixing the received optical power input to the optical receiver at a constant value. However, the BER-OSNR characteristics change depending on the received optical power, and the received optical power when the BER-OSNR characteristics are measured does not necessarily match the current received optical power or the planned received optical power. Therefore, a method for quantitatively evaluating the impact of changes in received optical power was needed.

[0007] The present disclosure has been made in consideration of the above circumstances, and an object of the present disclosure is to provide a technology that can quantitatively evaluate the impact of changes in received optical power on the relationship between signal quality and transmission quality of an optical transceiver.

[0008] An estimation device according to one aspect of the present disclosure includes a measurement unit that measures a signal quality or transmission quality value for each received optical power at an optical receiver for an optical transmitter and an optical receiver connected via a transmission path; a first calculation unit that calculates a penalty related to the signal quality or transmission quality that depends on the received optical power using the measured value of the signal quality or transmission quality for each received optical power at the optical receiver; and a second calculation unit that calculates a change in the relationship between the signal quality and transmission quality of the optical transmitter and the optical receiver in response to a change in the received optical power using the penalty related to the signal quality or transmission quality that depends on the received optical power.

[0009] An estimation method according to one aspect of the present disclosure is an estimation method performed by an estimation device, in which, for an optical transmitter and an optical receiver connected via a transmission path, a value of signal quality or transmission quality for each received optical power at the optical receiver is measured, a penalty related to the signal quality or transmission quality that depends on the received optical power is calculated using the measured value of signal quality or transmission quality for each received optical power at the optical receiver, and a change in the relationship between the signal quality and transmission quality of the optical transmitter and the optical receiver in response to a change in the received optical power is calculated using the penalty related to the signal quality or transmission quality that depends on the received optical power.

[0010] According to the present disclosure, it is possible to provide a technique capable of quantitatively evaluating the influence of a change in received optical power on the relationship between signal quality and transmission quality of an optical transceiver.

[0011] FIG. 1 is a diagram showing an example of the configuration of an estimation system according to this embodiment. FIG. 2 is a diagram showing another example of the configuration of an optical system. FIG. 3 is a diagram showing another example of the configuration of an optical system. FIG. 4 is a diagram showing another example of the configuration of an optical system. FIG. 5 is a diagram showing another example of the configuration of an optical system. FIG. 6 is a diagram showing measurement results of signal quality values ​​for each received optical power. FIG. 7 is a diagram showing comparison results between estimated values ​​and actual measured values ​​of BER-OSNR characteristics for each received optical power. FIG. 8 is a flow diagram showing a method for calculating the amount of change in BER-OSNR characteristics. FIG. 9 is a diagram showing an example of the hardware configuration of an estimation device.

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the description of the drawings, the same parts are designated by the same reference numerals and the description thereof will be omitted.

[0013] [Summary of the Present Disclosure] The present disclosure (a) measures and records signal quality or transmission quality values ​​(changes in signal quality or transmission quality values) while changing the received optical power at an optical receiver, and calculates a penalty related to signal quality or transmission quality that depends on the received optical power (received optical power dependent penalty) from the results. Furthermore, (b) uses the calculated received optical power dependent penalty to estimate and calculate the amount of change in BER-OSNR characteristics in response to changes in received optical power. This enables quantitative evaluation of the impact of changes in received optical power on BER-OSNR characteristics.

[0014] 1 is a diagram showing an example of the configuration of an estimation system 1 according to this embodiment. The estimation system 1 includes an optical transmitter 11, an optical receiver 12, an optical system 13, and an estimation device 14.

[0015] The optical transmitter 11 is a device that transmits an optical signal to the optical receiver 12. The optical receiver 12 is a device that receives the optical signal from the optical transmitter 11. The optical transmitter 11 and the optical receiver 12 are connected via a transmission path of an optical fiber and an optical system 13.

[0016] The optical system 13 is, in its simplest form, an optical fiber with a very short propagation distance. In this case, the optical transmitter 11 and the optical receiver 12 are connected in a back-to-back configuration by an optical fiber with a very short propagation distance.

[0017] 2 to 5 are diagrams showing other configuration examples of the optical system 13. FIG.

[0018] The optical system 13 shown in FIG. 2 includes a variable attenuator 131 that variably attenuates the optical signal from the optical transmitter 11, and a demultiplexer 132 that demultiplexes the variably attenuated optical signal to the optical receiver 12 and the optical spectrum analyzer 15.

[0019] The optical system 13 shown in FIG. 3 further includes an optical amplifier 133 for amplifying the optical signal from the optical transmitter 11, between the optical transceiver 11 and the variable attenuator 131 shown in FIG.

[0020] The optical system 13 shown in FIG. 4 includes an optical amplifier 133 that amplifies the optical signal from the optical transmitter 11, a variable attenuator 131 that variably attenuates the amplified optical signal, the optical amplifier 133 that amplifies the optical noise from the optical noise generating device 16, the variable attenuator 131 that variably attenuates the amplified optical noise, a multiplexer 134 that multiplexes the optical signal light after amplified and variably attenuated and the optical noise after amplified and variably attenuated, an optical bandpass filter 135 that passes only the desired light from the multiplexed light, and a demultiplexer 132 that demultiplexes the desired light to the optical receiver 12 and the optical spectrum analyzer 15.

[0021] The optical system 13 shown in FIG. 5 further includes a variable attenuator 131 for variably attenuating the desired light between the optical bandpass filter 135 and the demultiplexer 132 shown in FIG.

[0022] 2 to 5 is an example of a back-to-back configuration. For example, a plurality of attenuators with different fixed values ​​may be used instead of the variable attenuator 131, and the optical spectrum analyzer 15 may be omitted.

[0023] As shown in FIG. 1, the estimation device 14 is connected to each of the optical transmitter 11 or the optical system 13 and the optical receiver 12, and estimates the amount of change in the BER-OSNR characteristics (relationship between the signal quality and transmission quality of the optical transmitters and receivers (11, 12)) of the optical transceivers (11, 12) in response to a change in the received optical power at the optical receiver 12.

[0024] The estimation device 14 includes a measurement unit 141 , a first calculation unit 142 , and a second calculation unit 143 .

[0025] The measurement unit 141 has the function of measuring and recording the signal quality or transmission quality value (change in the signal quality or transmission quality value) for each received optical power at the optical receiver 12 while changing the received optical power at the optical receiver 12 by adjusting the output optical power from the optical transmitting side.

[0026] The output optical power from the optical transmission side is approximately equivalent to the received optical power at the optical receiver 12, and adjusting the output optical power at the optical transmitter 11 or the optical system 13 also changes the received optical power at the optical receiver 12. For example, when the optical transmitter 11 and the optical receiver 12 are connected only by an optical fiber, the measurement unit 141 measures and records the signal quality while changing the received optical power at the optical receiver 12 by adjusting the output optical power at the optical transmitter 11.

[0027] 2 and 3, the measurement unit 141 adjusts the output optical power using the variable attenuator 131. In the case of Fig. 4, the measurement unit 141 adjusts the output optical power using the variable attenuator 131 that variably attenuates the optical signal. In the case of Fig. 5, the measurement unit 141 adjusts the output optical power using the variable attenuator 131 that variably attenuates the desired light.

[0028] In order to realize this function, the measurement unit 141 includes, as shown in FIG. 1, an equipment control unit 141a that sets the optical transceivers (11, 12) to transmit and receive optical signals, an output optical power control unit 141b that adjusts the output optical power of the optical signal output from the optical transmitter 11 using the optical transmitter 11 or the optical system 13 in order to change the received optical power at the optical receiver 12, a received optical power measurement unit 141c that measures and records the received optical power of the optical signal input to the optical receiver 12, and a signal quality measurement unit 141d that measures the signal quality or transmission quality of the optical signal received by the optical receiver 12 and records it in association with the received optical power at the time of measurement.

[0029] The first calculation unit 142 has a function of calculating a penalty related to the signal quality or transmission quality that depends on the received optical power (received optical power dependent penalty) using the measured value of the signal quality or transmission quality for each received optical power measured by the measurement unit 141. The penalty is, for example, signal distortion.

[0030] For example, the first calculation unit 142 calculates the received optical power dependent penalty so that the measured value of signal quality for each received optical power matches the calculated value of signal quality calculated from the sum of a penalty related to signal quality that depends on received optical power (received optical power dependent penalty), a penalty related to signal quality that does not depend on received optical power (first received optical power independent penalty), and a penalty related to signal quality that does not depend on received optical power calculated from the optical noise level (OSNR) (second received optical power independent penalty).

[0031] The second calculation unit 143 has a function of calculating the amount of change in the BER-OSNR characteristics in response to a change in the received optical power, using the penalty (received optical power dependent penalty) related to the signal quality or transmission quality that depends on the received optical power calculated by the first calculation unit 142.

[0032] For example, when the received optical power changes from r0 to r1, the second calculation unit 143 calculates the penalty p0 when the received optical power is r0 and the penalty p1 when the received optical power is r1 from the calculation result of the received optical power dependent penalty, and calculates the amount of change in the BER-OSNR characteristics from the difference between the penalty p0 and the penalty p1.

[0033] Specifically, for example, the second calculation unit 143 calculates the amount of change in the BER-OSNR characteristic in response to a change in the received optical power by reflecting the difference in the received optical power-dependent penalty (the difference between the penalty p0 and the penalty p1) in the formula for calculating the BER-OSNR characteristic.

[0034] Hereinafter, the "signal quality or transmission quality value" will be described using the signal quality value (e.g., Q factor, Pre-FEC BER) as an example. Instead of signal quality, the "transmission quality value" such as optical signal noise level (OSNR) may be used.

[0035] [Method of Calculating Received Light Power Dependent Penalty] A method of calculating the received light power dependent penalty performed by the first calculation unit 142 will be described.

[0036] In this embodiment, an existing BER-OSNR model that does not take into account received optical power dependent penalties is extended so that received optical power dependent penalties can be taken into account.

[0037] The existing BER-OSNR model is expressed by equation (1).

[0038]

[0039] Equation (1) is described in "Toru Mano et al., "Modeling Transceiver BER-OSNR Characteristic for QoT Estimation in Short-Reach Systems," 2023 International Conference on Optical Network Design and Modeling (ONDM) (ONDM 2023), Coimbra, Portugal."

[0040] Ψ is a function determined by the signal modulation method. In the case of DP-16QAM, Ψ (SNR) = (3 / 8)erfc (√(SNR / 10)). SNR TRX is the SNR of the noise generated in the optical transceiver (11, 12). ASEis the SNR of ASE noise generated by optical noise generators and optical amplifiers (ASE), and is obtained by converting OSNR to SNR. NLI is the SNR of NLI noise generated by fiber nonlinear effects such as WDM.

[0041] In the back-to-back configuration, there is no wavelength multiplexing and the propagation distance of the optical fiber is very short, so the influence of the fiber nonlinear optical effect can be ignored. NLI is excluded from consideration.

[0042] To consider the received optical power dependent penalty, the received optical power is set as P in Then, the existing BER-OSNR model shown in equation (1) is extended as shown in equation (2).

[0043]

[0044] SNR TRX-in is the received optical power P from the noise generated in the optical transceiver (11, 12). in This SNR is the SNR excluding noise related to TRX-in corresponds to a penalty (first received optical power independent penalty) related to signal quality that is independent of received optical power.

[0045] SNR in P in is the received optical power P in is the SNR of the noise related to this SNR in corresponds to the penalty related to the signal quality that depends on the received optical power (received optical power dependent penalty). in When becomes smaller, the SNR in P in The signal quality will be degraded.

[0046] SNR ASE corresponds to a penalty (second received optical power independent penalty) related to signal quality that is independent of the received optical power calculated from the OSNR.

[0047] From equation (2), the received optical power P in The relationship between the signal quality (BER) and the BER can be expressed as in equation (3).

[0048]

[0049] From equation (3), the signal quality value (BER) is calculated by the received optical power P in and two parameters (SNR TRX-in -1 +SNR ASE -1 , SNR in ) and is determined by.

[0050] Therefore, the first calculation unit 142 calculates the received optical power P in The two parameters (SNR) are calculated using the least squares method or the like so that the measured signal quality (BER) for each channel matches the calculated signal quality (BER) calculated by Equation (3). TRX-in -1 +SNR ASE -1 , SNR in ) is calculated.

[0051] FIG. 6 shows the received optical power P in The horizontal axis shows the measurement results of the signal quality value (BER) for each received optical power P in The vertical axis is the signal quality value (Q value). The Q value and BER have a one-to-one relationship: BER = (1 / 2)erfc(Q / √(2)). By fitting the parameters using the least squares method, the parameter SNR of the received optical power dependent penalty can be calculated. in can be calculated.

[0052] [Method for Calculating the Amount of Change in BER-OSNR Characteristics Due to Change in Received Optical Power] A method for calculating the amount of change in BER-OSNR characteristics performed by the second calculation unit 143 will be described.

[0053] In order to estimate the amount of change in the BER-OSNR characteristic, the extended BER-OSNR model of Equation (2) is used. in ) into the second line of equation (2), the amount of change in the BER-OSNR characteristics in response to a change in the received optical power is calculated.

[0054] Received optical power P inA method for calculating the amount of change in the BER-OSNR characteristics when r changes from r0 to r1 will be explained.

[0055] Received optical power P in The BER-OSNR when the received optical power is r0 is assumed to be known, and the BER-OSNR when the received optical power is r1 is calculated. TRX is calculated from the BER-OSNR when the received optical power is r0 using the method described in the above-mentioned document "Modeling Transceiver BER-OSNR Characteristic for QoT Estimation in Short-Reach Systems." In this case, the received optical power P in The BER-OSNR when changes from r0 to r1 can be expressed as in equation (4).

[0056]

[0057] To explain again, the left side is SNR -1 In the formula, SNR in is the signal quality penalty that depends on the received optical power (received optical power dependent penalty), and SNR ASE is a penalty (second received optical power independent penalty) related to signal quality that is calculated from the OSNR and does not depend on the received optical power. ASE Since this equation relates the BER to the OSNR, the BER-OSNR characteristics can be calculated.

[0058] Using equation (4), the received optical power P in Therefore, the change in the BER-OSNR characteristics when the received optical power P in The effect of changes in the BER-OSNR characteristics can be quantitatively evaluated.

[0059] FIG. 7 shows the received optical power P in BER-OSNR characteristics (solid lines, etc.) and the measured received optical power P in The vertical axis represents the Q value, and the vertical axis represents the received optical power P inThe BER-OSNR characteristics for each channel were estimated. It can be seen that the estimated values ​​match well with the measured values.

[0060] [Operation of Estimation Device] FIG. 8 is a flowchart showing a method for estimating the amount of change in BER-OSNR characteristics performed by the estimation device 14. As shown in FIG.

[0061] Step S1: The measurement unit 141 measures the received optical power P in Measure and record the signal quality value (BER) for each signal.

[0062] Step S2: Next, the first calculation unit 142 calculates the received optical power P in The parameter of the received optical power dependent penalty (SNR) is calculated by using the least squares method or the like so that the measured signal quality (BER) for each signal matches the calculated signal quality (BER) calculated by Equation (3). in ) is calculated.

[0063] Step S3: Finally, the second calculation unit 143 calculates the parameter of the received light power dependent penalty (SNR in ) is used to calculate the received optical power P in The amount of change in the BER-OSNR characteristics when r changes from r0 to r1 is estimated and calculated.

[0064] [Effects] According to this embodiment, the estimation device 14 includes a measurement unit 141 that measures the signal quality or transmission quality value for each received optical power at the optical receiver 12 for the optical transmitter 11 and the optical receiver 12 connected via a transmission path, a first calculation unit 142 that calculates a penalty related to the signal quality or transmission quality that depends on the received optical power using the measured value of the signal quality or transmission quality for each received optical power at the optical receiver 12, and a second calculation unit 143 that calculates the amount of change in the BER-OSNR characteristics of the optical transceivers (11, 12) in response to a change in the received optical power using the penalty related to the signal quality or transmission quality that depends on the received optical power. Therefore, it is possible to quantitatively evaluate the influence that a change in the received optical power has on the relationship between the signal quality and transmission quality of the optical transceiver. Furthermore, it is possible to calculate the BER-OSNR characteristics for each received optical power, thereby accurately estimating the signal quality and calculating the transmission quality.

[0065] [Others] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present disclosure.

[0066] The estimation device 14 of the present embodiment described above can be realized, for example, by using a general-purpose computer system including a 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. 9. The memory 902 and the storage 903 are storage devices. In the computer system, the CPU 901 executes a predetermined program loaded onto the memory 902, thereby realizing each function of the estimation device 14.

[0067] The estimation device 14 may be implemented by one computer, or by multiple computers, or may be a virtual machine implemented on a computer.

[0068] The program for the estimation device 14 can be stored in a computer-readable recording medium such as a HDD, SSD, USB memory, CD, or DVD. The computer-readable recording medium is, for example, a non-transitory recording medium. The program for the estimation device 14 can also be distributed via a communication network.

[0069] REFERENCE SIGNS LIST 1 Estimation system 11 Optical transmitter 12 Optical receiver 13 Optical system 14 Estimation device 15 Optical spectrum analyzer 131 Variable attenuator 132 Demultiplexer 133 Optical amplifier 134 Multiplexer 135 Optical bandpass filter 141 Measurement unit 141a Equipment control unit 141b Output optical power control unit 141c Received optical power measurement unit 141d Signal quality measurement unit 142 First calculation unit 143 Second calculation unit 901 CPU 902 Memory 903 Storage 904 Communication device 905 Input device 906 Output device

Claims

1. An estimation apparatus comprising: a measurement unit that measures a value of signal quality or transmission quality for each received optical power at the optical receiver, for an optical transmitter and an optical receiver connected via a transmission line; a first calculation unit that calculates a penalty related to signal quality or transmission quality depending on the received optical power, using the measured value of signal quality or transmission quality for each received optical power at the optical receiver; and a second calculation unit that calculates a change amount of the relationship between the signal quality and the transmission quality of the optical transmitter and the optical receiver in response to a change in the received optical power, using the penalty related to signal quality or transmission quality depending on the received optical power.

2. The estimation apparatus according to claim 1, wherein the first calculation unit calculates the penalty related to signal quality depending on the received optical power such that a calculated value of signal quality, calculated from a measured value of signal quality for each received optical power at the optical receiver, a penalty related to signal quality depending on the received optical power, a penalty related to signal quality independent of the received optical power, and a penalty related to signal quality independent of the received optical power calculated from the optical noise amount, matches the measured value of signal quality for each received optical power at the optical receiver.

3. The estimation apparatus according to claim 1, wherein the second calculation unit calculates a change amount of the relationship between the signal quality and the transmission quality of the optical transmitter and the optical receiver in response to a change in the received optical power, by including the penalty in response to the change in the received optical power in an equation for calculating the relationship between the signal quality and the transmission quality of the optical transmitter and the optical receiver.

4. The estimation apparatus according to claim 1, wherein the measurement unit measures a value of signal quality or transmission quality for each received optical power at the optical receiver while changing the received optical power at the optical receiver by adjusting the output optical power on the optical transmission side.

5. An estimation method performed by an estimation apparatus, the method comprising: measuring a value of signal quality or transmission quality for each received optical power at the optical receiver, for an optical transmitter and an optical receiver connected via a transmission line; calculating a penalty related to signal quality or transmission quality depending on the received optical power, using the measured value of signal quality or transmission quality for each received optical power at the optical receiver; and calculating a change amount of the relationship between the signal quality and the transmission quality of the optical transmitter and the optical receiver in response to a change in the received optical power, using the penalty related to signal quality or transmission quality depending on the received optical power.

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