Optical transmission design device and optical transmission design system

Abstract

An optical transmission design device (100) disclosed herein comprises: a noise characteristic information acquisition unit (110) that acquires noise characteristic information of an optical transmission device; an OSNR deterioration amount calculation unit (120) that uses the noise characteristic information, acquired by the noise characteristic information acquisition unit (110), to calculate the amount of optical signal-to-noise ratio deterioration that occurs when an optical signal passes through the optical transmission device; a nonlinear waveform distortion calculation unit (130) that calculates the nonlinear waveform distortion of an optical transmission path; and a transmission reachability evaluation unit (140) that compares a value obtained by subtracting the nonlinear waveform distortion from the amount of optical signal-to-noise ratio deterioration calculated by the OSNR deterioration amount calculation unit (120) with the performance of a single optical transmission / reception device (30) to evaluate the transmission reachability of a wavelength multiplex transmission system (1000).

Description

Optical transmission design device and optical transmission design system

[0001] The present invention relates to an optical transmission design device and an optical transmission design system for a wavelength multiplexing transmission system that transmits wavelength multiplexed signal light, which is obtained by multiplexing optical signals in a plurality of different wavelength bands, through an optical fiber.

[0002] Conventionally, wavelength cross-connect devices are connected as relay nodes for optical signals to optical fibers of a path (optical transmission path) that bundles together multiple optical fibers in an optical network. Wavelength cross-connect devices are used, for example, in reconfigurable optical add / drop multiplexers (ROADMs) that act as path switches for optical signals transmitted using various modulation methods such as wavelength division multiplexing in optical networks. In these wavelength cross-connect devices, wavelength-multiplexed signal light transmitted from an input path is output to an output path via multiple wavelength selective switches (WSSs) (Non-Patent Document 1).

[0003] A wavelength selective switch is an optical switch that not only has the wavelength multiplexing / demultiplexing function of connecting input WDM (Wavelength Division Multiplexing) signals to different output ports for each wavelength, but also has the ability to change the combination of wavelength and output port.Using a wavelength selective switch, on-site work is not required when changing the sending and receiving wavelengths, and path changes can be made quickly by remote operation.

[0004] 6 is a diagram illustrating the transmission reachability of a wavelength multiplexing transmission system equipped with ROADM devices. The wavelength multiplexing transmission system 1 shown in FIG. 6 includes ROADM devices 60a-60e constituting optical cross-connects (OXCs) that are optical nodes; paths 70a-70d that are optical transmission paths consisting of optical fibers connecting the OXCs; transponder accommodating units 80a-80c having an optical multiplexing unit 81 that connects desired wavelengths of WDM signals from multiple paths input and output to the ROADM device 60 to desired transponders (TRPDs); open transponders 91a and 91b of company A; open transponders 92a and 92b of company B; and existing transponders 90a and 90b. The open transponders 91a and 91b of company A are collectively referred to as the open transponder 91 of company A. The B company open transponders 92a and 92b are collectively referred to as the B company open transponder 92. The existing transponders 90a and 90b are collectively referred to as the existing transponder 90.

[0005] The transponder 90 relays client signals such as GbE / 10GbE / 100GbE / 400GbE transmitted and received via an optical transmission path such as an optical fiber between the client and the transponder 90. Information about the client and other information is superimposed on the optical signal. Note that Fig. 6 omits the illustration of a REP (repeater) device, which is an optical amplifier repeater provided between multiple stages of ROADM devices 60.

[0006] The optical multiplexer 81 has CD (Colorless, Directionless) / CDC (Colorless, Directionless, Contentionless) functions. With the colorless function, the wavelength input and output to the port is no longer a fixed wavelength, and the transponder wavelength can be changed without changing the physical connection. Here, " / " means "or."

[0007] The Directionless function allows the input and output directions of ports to be freely set instead of fixed directions. The Contentionless function allows optical signals of the same wavelength assigned to different directions to communicate without collisions within the device. The CDC function, which allows for flexible changes to port settings, is an advantageous function in that it improves operability by enabling remote port settings, and also ensures reliability economically.

[0008] <Vendors of wavelength multiplexing transmission system 1> The wavelength multiplexing transmission system 1 shown in Figure 6 is developed, constructed, and operated by the following All-Photonics Network Interchange (APN-I), All-Photonics Network Gateway (APN-G), and All-Photonics Network Transceiver (APN-T).

[0009] The All-Photonics Network Interchange is a relay function unit for optical paths, and has functions of wavelength cross-connect and adaptation between interfaces. The All-Photonics Network Interchange corresponds to the ROADM devices 60a to 60e in FIG. 6.

[0010] The All-Photonics Network Gateway is an optical path gateway that has the functions of setting control channels for the accommodated All-Photonics Network transceivers, user plane admission control of optical signals, multiplexing and demultiplexing of optical paths, return connection of optical paths, and multiplexing / demultiplexing of optical paths. The All-Photonics Network Gateway corresponds to the transponder accommodating units 80a to 80d in Figure 6.

[0011] The all-photonics network transceiver is an end point of an optical path and has the function of transmitting and receiving optical signals. The all-photonics network transceiver corresponds to the existing transponders 90a and 90b in FIG.

[0012] The ROADM devices 60a to 60e, transponder housing units 80a to 80d, and existing transponders 90a and 90b enclosed in a shaded area in FIG. 6 are existing devices.

[0013] As shown by the dashed dotted line, the existing transponder 90a is connected to the existing transponder 90d via the transponder accommodating unit 80a and five ROADM devices 60a to 60e. New open transponders 91a and 91b from company A and open transponders 92a and 92b from company B are introduced into the wavelength multiplexing transmission system 1 constructed with the existing ROADM devices 60a to 60e, transponder accommodating units 80a to 80d, and existing transponders 90a to 90b.

[0014] As shown by the thick dashed lines, the open transponder 91a of company A is connected to the open transponder 92b of company B via the transponder accommodating unit 80a, the three ROADM devices 60a to 60c, and the transponder accommodating unit 80b. As shown by the thick solid lines, the open transponder 92a of company B is connected to the open transponder 91b of company A via the transponder accommodating unit 80a, the ROADM devices 60a to 60d, and the transponder accommodating unit 80c.

[0015] <Comparison of Transponder Specifications> Figure 7 is a table showing the specifications of the open transponder 91 from Company A, the open transponder 92 from Company B, and the existing transponder 90. The open transponder 91 from Company A, the open transponder 92 from Company B, and the existing transponder 90 differ in the specifications of signal rate, baud rate, modulation method, and minimum received OSNR (Optical Signal to Noise Ratio). The open transponder 91 from Company A has a signal rate of 200 Gbps, a baud rate of 60 Gbaud, a modulation method of QPSK (Quadrature Phase-Shift Keying), and a minimum received OSNR of d1 dB. The open transponder 92 from Company B has a signal rate of 400 Gbps, a baud rate of 63.1 Bbaud, a modulation method of 16QAM (16-Quadrature Amplitude Modulation), and a minimum received OSNR of d2 dB. The signal rate of the existing transponder 90 is 800 Gbps, the baud rate is 135 Gbaud, the modulation method is PCS-16QAM (Probabilistic Constellation Shaping), and the minimum received OSNR is d3 dB.

[0016] When a new vendor joins the existing ROADM devices 60a to 60e, transponder accommodating units 80a to 80d, and existing transponders 90a and 90b, the following problems arise: (1) Entry of a New Vendor When new open transponders 91a and 91b of company A and open transponders 92a and 92b of company B are introduced into the wavelength multiplexing transmission system 1 constructed with the existing ROADM devices 60a to 60e, transponder accommodating units 80a to 80d, and existing transponder 90, it is necessary to know the transmission reachability of the wavelength multiplexing transmission system 1. However, it is unclear to what extent existing vendors that provide all-photonics network interchanges, all-photonics network gateways, and all-photonics network transceivers will provide information on transmission reachability, etc. to vendors that provide Company A's open transponders 91a and 91b and Company B's open transponders 92a and 92b.

[0017] (2) Transmission distance of wavelength paths when the vendors are different: When the All-Photonics Network Interchange, All-Photonics Network Gateway, and transponder are from the same vendor, the transmission distance of the wavelength path can be determined using a transmission evaluation tool provided by the vendor, and optimal tuning by the same vendor will maximize transmission performance.

[0018] - When the All-Photonics Network Interchange and All-Photonics Network Gateway are from different vendors than the transponder (for example, in the case of an open optical IF connection configuration), the transmission evaluation tools provided by the vendors cannot be used, making it difficult to guarantee performance.

[0019] <Major factors that determine transmission reachability> The major factors that determine transmission reachability are described below. The major factors that determine transmission reachability are (1) to (4) below. (1) Noise generated in the optical amplifier (OSNR degradation) (2) Waveform distortion due to nonlinear effects, etc. (3) Degradation due to fluctuations in the transmission path, etc. (4) Transponder receiving capability limit (ROSNR)

[0020] The above factors (1) to (3) are signal degradation factors. In the wavelength multiplexing transmission system 1 shown in Figure 6, the signal degradation factors (1) to (3) correspond to the following: Signal degradation factor (1): Loss in the ROADM device 60 and the REP device (not shown). Specifically, this is optical noise due to the optical amplifiers in the ROADM device 60 and the REP device. This corresponds to the amount of OSNR degradation.

[0021] Signal degradation factor (2): Waveform degradation (particularly nonlinear waveform distortion) that accompanies optical fiber transmission in the path 70.

[0022] Signal degradation factor (3): Additional degradation due to fluctuations in SOP (State Of Polarization), PDL (Polarization Dependent Loss), or transmission path loss.

[0023] <Image of transmission reachability assessment> An image of transmission reachability assessment will be described. Figure 8 is a diagram showing an example of transmission reachability assessment based on the degree of signal degradation when there are signal degradation factors (1) to (3) in the wavelength multiplexing transmission system 1 shown in Figure 6. The horizontal axis of Figure 6 represents the open transponder 91 of company A, the open transponder 92 of company B, and the existing transponder 90, and the vertical axis represents the degradation degree of each transponder.

[0024] As shown in Figure 8, the degree of degradation for each transponder is a cumulative superposition of the signal degradation factors (1) to (3). Region a of the bar graph in Figure 8 represents signal degradation factor (1): noise generated in the optical amplifier, resulting from OSNR degradation. Region b of the bar graph in Figure 8 represents signal degradation factor (2): waveform distortion due to nonlinear effects, etc. Region c of the bar graph in Figure 8 represents signal degradation factor (3): degradation due to fluctuations in the transmission path, etc. Figure 8 schematically shows threshold levels d1, d2, and d3 for determining whether or not transmission is possible for each transponder based on the degree of degradation. As shown in Figure 7, each transponder has different specifications for signal rate, baud rate, modulation method, and minimum receive OSNR, and therefore the threshold levels d1, d2, and d3 for determining the degree of degradation also differ.

[0025] As shown in Figure 8, the A company open transponder 91 is permitted to transmit because its degree of degradation has not reached the threshold level d1, which is the transmission judgment level. The B company open transponder 92 has approximately the same degree of degradation as the A company open transponder 91, but has reached the transmission judgment level threshold level d2, which is the transmission judgment level, and therefore is not permitted to transmit. The existing transponder 90 is permitted to transmit because it has not reached the transmission judgment level threshold level d3. Note that even if the transmission judgment level threshold level d3 of the existing transponder 90 were the same as the transmission judgment level threshold level d2 of the B company open transponder 90B, there is a high possibility that the existing transponder 90 would be permitted to transmit because of its small degree of degradation.

[0026] <Method for assessing transmission reachability when design information is disclosed> This section describes a method for assessing transmission reachability when design information is disclosed. When detailed design information of a ROADM device is disclosed, it is possible to estimate OSNR degradation and nonlinear waveform distortion using a general-purpose assessment tool such as GNPy, and to assess transmission reachability to a certain extent (Non-Patent Document 2).

[0027] GNPy is an open-source library for evaluating transmission reachability in actual mesh optical networks. GNPy is a design tool based on the Gaussian noise model approximation, which is applicable when there is little nonlinear waveform distortion. Therefore, evaluation is not possible when there is little nonlinear waveform distortion. Furthermore, GNPy requires a large number of input parameters for optical amplifiers alone, and it is expected that it would be practically difficult for anyone other than the supplier of ROADM equipment to input such parameters.

[0028] Furthermore, unlike experimental equipment, commercial equipment has a complex configuration, making it practically difficult to check each parameter individually and input it into the tool. Parameters for commercial equipment include (1) fiber information in the transmission route, (2) the internal configuration of the ROADM device, the amplification characteristics (gain) and noise characteristics of the optical amplifier, and (3) the optical level diagram in the transmission path and ROADM device.

[0029] Furthermore, it is practically difficult to accurately estimate the OSNR parameters related to the loss of the ROADM device and the noise characteristics of the optical amplifiers. That is, the optical amplifiers built into the ROADM devices used in commercial devices are implemented in multiple stages, and components such as optical attenuators are inserted between the multi-stage optical amplifiers, resulting in a complex configuration.

[0030] Mitsushi Fukutoku and two others, "Optical node and switch technology for flexible and economical networks," NTT Technical Journal, [online], [Retrieved August 1, 2024], Internet <URL: https: / / journal.ntt.co.jp / backnumber2 / 1311 / files / jn201311012.pdf> gnpy.core, [online], [Retrieved August 1, 2024], Internet <URL: https: / / gnpy.readthedocs.io / en / master / >

[0031] Consider a case where wavelength multiplexing transmission is performed by accommodating transponders or optical transceivers, which are optical transmitters and receivers provided by a supplier different from the supplier of the ROADM or REP devices, which are optical transmission devices in a wavelength multiplexing transmission system, in an existing ROADM device. The supplier of the optical transmitters and receivers does not have information about the detailed specifications or functions of the ROADM or REP devices, which are optical transmission devices. In other words, the internal design information of the ROADM or REP devices is generally kept confidential, and such internal design information is not provided by the supplier of these ROADM or REP devices. For this reason, it is difficult to accurately determine the transmission reachability of the optical transmission device.

[0032] Furthermore, even if a general-purpose design tool such as GNPy is used, in addition to its own performance limitations, the input parameters can be complicated, and it can be practically difficult to set parameters for the complex configuration of commercial equipment.

[0033] Due to the difficulty of setting the above parameters, it is common for optical transmission equipment such as ROADM devices and REP devices, and optical transmitters and receivers to be provided by the same supplier, and long-distance transmission systems are constructed in a way that ensures transmission reachability.

[0034] When applying optical transceiver equipment from a supplier other than the supplier of an existing ROADM device to the existing ROADM device, precise transmission reachability evaluation assuming passage through multiple ROADM devices or REP devices is omitted, and in many cases the application is limited to extremely short-distance routes.

[0035] The present invention has been made in consideration of the above circumstances, and aims to provide an optical transmission design device and an optical transmission design system that can accurately evaluate transmission reachability during long-distance transmission that assumes passage through multiple optical transmission devices, without receiving internal design information from an optical transmission device supplier.

[0036] In order to solve the above-mentioned problems, there is provided an optical transmission design device for evaluating the transmission reachability of a wavelength multiplexing transmission system in which an optical signal passes through multiple stages of optical transmission devices having optical transmitters and receivers that relay client signals and optical amplifiers, the optical transmission design device comprising: a noise characteristic information acquisition unit that acquires noise characteristic information of the optical transmission devices; an OSNR degradation amount calculation unit that calculates an amount of optical signal-to-noise ratio degradation that occurs when an optical signal passes through the optical transmission devices, using the noise characteristic information acquired by the noise characteristic information acquisition unit; a nonlinear waveform distortion calculation unit that calculates nonlinear waveform distortion of an optical transmission path; and a transmission reachability evaluation unit that evaluates the transmission reachability of the wavelength multiplexing transmission system by comparing a value obtained by subtracting the nonlinear waveform distortion from the amount of optical signal-to-noise ratio degradation calculated by the OSNR degradation amount calculation unit with the performance of the optical transmitters and receivers alone.

[0037] The optical transmission design device of the present invention can accurately evaluate transmission reachability during long-distance transmission assuming passage through multiple optical transmission devices, without receiving internal design information from a supplier of the optical transmission device.

[0038] FIG. 1 is a configuration diagram showing a wavelength multiplexing transmission system including an optical transmission design device according to an embodiment of the present invention. FIG. 2 is a diagram showing the optical level and noise level equivalent to the signal of pseudo light of each wavelength λ by a pseudo light source of the optical transmission design device according to an embodiment of the present invention. FIG. 3 is a block diagram showing the configuration of the optical transmission design device according to an embodiment of the present invention. FIG. 4 is a flowchart showing the transmission reachability evaluation process of the optical transmission design device according to an embodiment of the present invention. FIG. 5 is a hardware configuration diagram of a server according to an embodiment of the present invention. FIG. 6 is a diagram explaining the transmission reachability of a wavelength multiplexing transmission system including a conventional ROADM device. FIG. 7 is a diagram showing in a table the specifications of a company A open transponder, a company B open transponder, and an existing transponder. FIG. 8 is a diagram showing an example of transmission reachability evaluation from the degree of signal degradation when there is a signal degradation factor in the wavelength multiplexing transmission system shown in FIG.

[0039] An optical network system and the like in an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described below with reference to the drawings. (Embodiment) Fig. 1 is a configuration diagram showing a wavelength multiplexing transmission system equipped with an optical transmission design apparatus according to an embodiment of the present invention.

[0040] 1 includes ROADM devices 10a and 10b, wavelength signal accommodating units 20a and 20b that accommodate route-switched wavelength signals, a plurality of optical transceivers 30 that transmit and receive optical signals to and from the wavelength signal accommodating units 20, an REP device 40 having an optical amplifier 11, a Network Element Operation System (NE-OpS) 50 that is a monitoring and control device that controls the ROADM devices 10, and an optical transmission design device 100 that evaluates the transmission reachability of the wavelength multiplexing transmission system 1000 in cooperation with the NE-OpS 50. The plurality of ROADM devices 10a and 10b having optical transceivers 30 that relay client signals, and the optical transmission design device 100 that evaluates the transmission reachability of the wavelength multiplexing transmission system that passes optical signals across the plurality of optical transmission devices, constitute an optical transmission design system.

[0041] The ROADM devices 10a and 10b are path switching units, and when there is no need to distinguish between them, they are referred to as the ROADM device 10. The ROADM devices 10a and 10b are optical transmission devices that constitute an optical cross-connect device (OXC), which is an optical node. The REP device 40 is an optical amplification repeater unit having an optical amplifier 11, and is also an optical transmission device.

[0042] The optical transmission design device 100 is connected to the NE-OpS 50. The NE-OpS 50, which is a monitoring and control device, is connected to the ROADM devices 10a and 10b. The ROADM device 10a, the REP device 40, and the ROADM device 10b are each connected by a path 2, which is an optical transmission path made of optical fiber.

[0043] <ROADM Devices 10a, 10b> The ROADM devices 10a, 10b each include optical amplifiers 11-1, 11-2, a wavelength / direction switch 12, optical demultiplexers 13-1, 13-2, a spectrum monitor 14, a pseudo light source 15, and an optical multiplexer 16. The wavelength / direction switch 12 is referred to as WSS in the drawings. The optical amplifiers 11-1, 11-2 are referred to collectively as optical amplifier 11. The optical demultiplexers 13-1, 13-2 are referred to collectively as optical demultiplexer 13. Hereinafter, when there is no need to distinguish between the ROADM devices 10a, 10b, they will simply be referred to as the ROADM device 10a.

[0044] The optical demultiplexer 13-1 demultiplexes the input light to the ROADM device 10 and inputs the demultiplexed light to the spectrum monitor 14. The optical demultiplexer 13-2 demultiplexes the output light from the ROADM device 10 and inputs the demultiplexed light to the spectrum monitor 14.

[0045] The spectrum monitor 14 measures the optical level and noise level of each wavelength at the input and output of the ROADM device 10. The spectrum monitor 14 transmits the acquired data on the optical level and noise level of each wavelength, together with performance information including a pseudo light source, to the NE-OpS 50. In other words, the data on the optical level and noise level of each wavelength acquired by the spectrum monitor 14 is collected and stored by the NE-OpS 50 as performance information including a pseudo light source.

[0046] The pseudo light source 15 generates pseudo light that complements the signal waveform input to the optical amplifier 11. The pseudo light source 15 generates pseudo light O of a predetermined wavelength λ and sends the generated pseudo light O to the optical multiplexer 16. The pseudo light source 15 is multiplexed with the output light of the wavelength / direction switch 12 to keep the input light level to the optical amplifier 11-2 constant.

[0047] The pseudo light source 15 is used to keep the input light level of the optical amplifier 11 of the ROADM devices 10a, 10b and the REP device 40 constant and to stabilize the amplification operation of the optical amplifier 11, regardless of the number of optical transceivers 30 applied.

[0048] FIG. 2 shows the pseudo light O of each wavelength λ generated by the pseudo light source 15. Ａ , O Ｂ , O Ｃ , ..., O Ｎ 1 is a diagram showing the optical level σ corresponding to the signal and the noise level ν of the pseudo light O Ａ , O Ｂ , O Ｃ , ..., O Ｎ The input optical level of the optical amplifier 11 of the ROADM device 10 and the REP device 40 depends on the number of nodes of the ROADM device 10, that is, the number of optical transceivers 30 connected to the ROADM device 10. If the number of optical transceivers 30 is small, the input optical level becomes small and the optical level corresponding to the signal cannot be measured accurately. By providing the ROADM device 10 with the pseudo light source 15, even if only a small number of optical transceivers 30 are installed, the pseudo light source 15 can complement the signal wavelength (the pseudo light O in FIG. 2 ). Ａ , O Ｂ , O Ｃ , ..., O Ｎ By using the pseudo light source 15 of the ROADM device 10 on the left side of FIG. 1, the optical level can be kept constant over the entire optical band, and the optical level equivalent to the signal and the noise level can be measured. Ａ The pseudo light source 15 of the ROADM device 10 on the right side of FIG. Ｂ It was decided.

[0049] The optical multiplexer 16 multiplexes the optical signal output from the wavelength / direction switch 12 and the quasi-light O from the quasi-light source 15, and sends the multiplexed signal to the optical amplifier 11-2.

[0050] <Wavelength signal accommodating unit 20> The wavelength signal accommodating unit 20 connects a desired wavelength to a desired transponder for a WDM signal from multiple paths input and output to the ROADM device 10. The wavelength signal accommodating unit 20 includes an optical multiplexing unit (not shown) that supports CD / CDC functions, similar to the transponder accommodating unit 80 in Fig. 6 .

[0051] <Optical Transmitter / Receiver 30> The optical transmitter / receiver 30 relays client signals transmitted and received via the ROADM device 10, which is an optical transmission device, or the REP device 40. The optical transmitter / receiver 30 is a transponder or optical transceiver, for example, an open optical transceiver. The transponder is, for example, the open transponders 91a and 91b of Company A, the open transponders 92a and 92b of Company B, or the existing transponders 90a and 90b shown in FIG. 6. If the optical transmitter / receiver 30 is the open transponder 91 of Company A or the open transponder 92 of Company B shown in FIG. 6, the optical transmitter / receiver 30 is a device from a different supplier than the ROADM device 10 or the REP device 40.

[0052] <REP Device 40> The REP device 40 is an optical transmission device, and includes an optical amplifier 11, optical demultiplexers 13-1 and 13-2, and a spectrum monitor 14.

[0053] <NE-OpS 50> The NE-OpS 50 is a transmission controller and a monitoring and control device that monitors and controls the operation, maintenance, etc. of the ROADM device 10. The NE-OpS 50 also collects and stores data on the optical level and noise level of each wavelength acquired by the spectrum monitor 14 of each optical transmission device as noise characteristic information, and transmits the noise characteristic information collected from each optical transmission device to the optical transmission design device 100 in response to a request from the optical transmission design device 100.

[0054] 3 is a block diagram showing the configuration of the optical transmission design apparatus 100. The optical transmission design apparatus 100 includes a noise characteristic information acquisition unit 110, an OSNR degradation amount calculation unit 120, a nonlinear waveform distortion calculation unit 130, and a transmission reachability evaluation unit 140.

[0055] The noise characteristic information acquisition unit 110 acquires noise characteristic information of the ROADM device 10 or the REP device 40, which are optical transmission devices. Specifically, the noise characteristic information acquisition unit 110 acquires noise characteristic information from the NE-OpS 50, which collects and stores data on the optical level and noise level of each wavelength acquired by the spectrum monitor 14 of each ROADM device 10, which is an optical transmission device, as noise characteristic information. In other words, the data on the optical level and noise level of each wavelength acquired by the spectrum monitor 14 is stored in the NE-OpS 50 as noise characteristic information, and the noise characteristic information acquisition unit 110 acquires this noise characteristic information from the NE-OpS 50.

[0056] The OSNR degradation amount calculation unit 120 uses the acquired noise characteristic information to calculate the amount of degradation in the optical signal-to-noise ratio that occurs when the optical signal passes through the ROADM device 10 or the REP device 40, which are optical transmission devices. The OSNR degradation amount calculation unit 120 calculates the received OSNR when the signal is transmitted along the route to be evaluated, thereby calculating the amount of degradation in the optical signal-to-noise ratio that occurs when the signal passes through each of the ROADM device 10 and the REP device 40. Specifically, the OSNR degradation amount calculation unit 120 uses the acquired noise characteristic information to calculate the span loss dependency of the amplification characteristics and noise characteristics of the optical amplifier, and derives the received OSNR by estimating the optical noise that occurs when the optical transmitting / receiving device 30 passes through the ROADM device 10 or the REP device 40 when transmitting along the route to be evaluated.

[0057] The nonlinear waveform distortion calculation unit 130 calculates the nonlinear waveform distortion of the optical transmission line. Specifically, the nonlinear waveform distortion calculation unit 130 uses a general-purpose design tool 3 including GNPy to calculate the nonlinear waveform distortion based on the parameters of the transmission line fiber and the conditions of the optical level diagram, thereby estimating the degradation. When using the general-purpose design tool 3, the nonlinear waveform distortion can be derived by inputting the parameters of the transmission line fiber and the conditions of the optical level diagram. Here, the parameters of the transmission line fiber may be obtained by using input / output level data of the ROADM device 10 collected by the NE-OpS 50, or by using fiber parameter design information.

[0058] The transmission reachability evaluation unit 140 evaluates the transmission reachability of the wavelength multiplexing transmission system by comparing the value obtained by subtracting the nonlinear degradation from the calculated OSNR with a known ROSNR (Required-OSNR), which is the performance of the optical transceiver 30 alone, as specified in the optical transceiver 30. That is, the transmission reachability evaluation unit 140 compares the value obtained by subtracting the "nonlinear waveform distortion" calculated by the nonlinear waveform distortion calculation unit 130 from the "optical signal-to-noise ratio degradation amount" calculated by the OSNR degradation amount calculation unit 120 with the performance (ROSNR) of the optical transceiver 30 alone, thereby precisely evaluating the transmission reachability during long-distance transmission assuming passage through multiple stages of ROADM devices 10 and / or REP devices 40.

[0059] The following describes the transmission reachability evaluation operation of the optical transmission design apparatus 100 configured as described above. Figure 4 is a flowchart showing the transmission reachability evaluation process of the optical transmission design apparatus 100. In step S11, the NE-OpS 50 shown in Figure 1 collects data on the optical level and noise level of each wavelength acquired by the spectrum monitor 14 of each ROADM device 10, and saves the data as noise characteristic information.

[0060] In step S12, the noise characteristic information acquisition unit 110 of the optical transmission design apparatus 100 shown in FIG. 2 acquires noise characteristic information such as the noise characteristic of the ROADM device 10 from the NE-OpS 50.

[0061] In step S13, the OSNR degradation amount calculation unit 120 uses the acquired noise characteristic information to calculate the amount of degradation in the optical signal-to-noise ratio that occurs when the optical signal passes through the optical transmission device, the ROADM device 10, or the REP device 40. In other words, the OSNR degradation amount calculation unit 120 uses the acquired noise characteristic information to calculate the amount of degradation in the optical signal-to-noise ratio that deteriorates as the signal passes through each of the ROADM device 10 and the REP device 40.

[0062] In step S14, the nonlinear waveform distortion calculation unit 130 calculates the nonlinear waveform distortion (degradation estimation) using the general-purpose design tool 3 including GNPy. When using the general-purpose design tool 3 including GNPy, the nonlinear waveform distortion can be derived by inputting the parameters of the transmission line fiber and the conditions of the optical level diagram.

[0063] In step S15, the transmission reachability evaluation unit 140 evaluates the transmission reachability by comparing the value obtained by subtracting the nonlinear degradation from the calculated OSNR with the ROSNR (Required-OSNR), which is the performance of the optical transceiver 30 itself defined in the optical transceiver 30, and ends the processing of this flow. Specifically, the transmission reachability evaluation unit 140 adds together the "optical signal-to-noise ratio degradation amount" calculated by the OSNR degradation amount calculation unit 120 and the "nonlinear waveform distortion" calculated by the nonlinear waveform distortion calculation unit 130, and compares the result with the performance (ROSNR) of the optical transceiver 30 itself, thereby precisely evaluating the transmission reachability during long-distance transmission that assumes passage through multiple stages of ROADM devices 10 and / or REP devices 40.

[0064] [Hardware Configuration] The optical transmission design apparatus 100 of FIG. 1 according to each of the above embodiments is realized by a computer 900 configured as shown in FIG. 5, for example.

[0065] Fig. 5 is a hardware configuration diagram showing a computer 900. The computer 900 has a CPU 901, a ROM 902, a RAM 903, a HDD 904, a communication interface 906, an input / output interface 905, and a media interface 907. Note that in Fig. 4, the interface is abbreviated as "I / F."

[0066] The CPU 901 operates based on programs stored in the ROM 902 or the HDD 904, and embodies each unit of the optical transmission design apparatus 100 ( FIG. 1 ). The ROM 902 stores a boot program executed by the CPU 901 when the computer 900 is started, programs dependent on the hardware of the computer 900, and the like.

[0067] The CPU 901 controls an input device 910 such as a mouse or keyboard, and an output device 911 such as a display, via an input / output interface 905. The CPU 901 acquires data from the input device 910 via the input / output interface 905, and outputs generated data to the output device 911. Note that a GPU (Graphics Processing Unit) or the like may be used as a processor together with the CPU 901.

[0068] The HDD 904 stores programs executed by the CPU 901 and data used by the programs. The communication interface 906 receives data from other devices via a communication network (e.g., network 922) and outputs the data to the CPU 901, and also transmits data generated by the CPU 901 to other devices via the communication network.

[0069] The media interface 907 reads a program or data stored in the recording medium 912 and outputs it to the CPU 901 via the RAM 903. The CPU 901 loads a program related to a target process from the recording medium 912 onto the RAM 903 via the media interface 907, and executes the loaded program. The recording medium 912 is an optical recording medium such as a DVD (Digital Versatile Disc) or a PD (Phase Change Rewritable Disc), a magneto-optical recording medium such as an MO (Magneto Optical Disc), a magnetic recording medium, a conductive memory tape medium, a semiconductor memory, or the like.

[0070] For example, when the computer 900 functions as the optical transmission design apparatus 100 of the present embodiment shown in FIG. 1 , the CPU 901 of the optical transmission design apparatus 100 executes a program loaded onto the RAM 903 to realize the functions of the optical transmission design apparatus 100. The HDD 904 stores data in the RAM 903. The CPU 901 reads and executes a program related to a target process from a recording medium 912. Alternatively, the CPU 901 may read a program related to a target process from another device via a communication network 922.

[0071] [Effects] As described above, the optical transmission design device 100 (FIG. 1) evaluates the transmission reachability of the wavelength multiplexing transmission system 1000 (FIG. 1) in which an optical signal passes through a plurality of stages in an optical transmission device having an optical transmitting / receiving device 30 that relays a client signal and an optical amplifier 11, and includes a noise characteristic information acquisition unit 110 (FIG. 3) that acquires noise characteristic information of the optical transmission device (ROADM device 10, REP device 40) (FIG. 1), and a noise characteristic information acquisition unit 110 ...) and an optical transmission device (ROADM device 10, REP device 40) (FIG. 1) in which the optical signal passes through the optical transmission device (ROADM device 10, REP device 40) (FIG. 1). The wavelength-multiplexing transmission system 1000 includes an OSNR degradation amount calculation unit 120 (FIG. 3) that calculates the amount of degradation of the optical signal-to-noise ratio that occurs when the optical signal passes through the optical transmission line (OADM device 10, REP device 40), a nonlinear waveform distortion calculation unit 130 (FIG. 3) that calculates the nonlinear waveform distortion of the optical transmission line, and a transmission reachability evaluation unit 140 (FIG. 3) that evaluates the transmission reachability of the wavelength-multiplexing transmission system 1000 by comparing the value obtained by subtracting the nonlinear waveform distortion from the amount of degradation of the optical signal-to-noise ratio calculated by the OSNR degradation amount calculation unit 120 with the performance of the optical transmitting and receiving device 30 alone.

[0072] This makes it possible to precisely evaluate the transmission reachability during long-distance transmission assuming passage through multiple stages of ROADM devices 10 and REP devices 40, without receiving internal design information, which is generally kept secret, from suppliers of the ROADM devices 10 and REP devices 40. As a result, the transmission performance of the optical transmitting and receiving device 30 (transponder, optical transceiver) can be maximized in the existing wavelength multiplexing transmission system 1000 ( FIG. 1 ).

[0073] In the optical transmission design apparatus 100 (FIG. 1), the nonlinear waveform distortion calculation unit 130 (FIG. 3) derives nonlinear waveform distortion based on the parameters of the optical transmission line and the conditions of the optical level diagram.

[0074] For example, the nonlinear waveform distortion calculation unit 130 (FIG. 3) can derive nonlinear waveform distortion by using a general-purpose design tool 3 (FIG. 3) such as GNPy. The general-purpose design tool 3 (FIG. 3) such as GNPy can estimate the amount of degradation of the optical signal-to-noise ratio and nonlinear waveform distortion, making it possible to assess transmission reachability to a certain extent. Although commercial equipment has a complex configuration, the transmission reachability evaluation unit 140 can add up the "degradation of the optical signal-to-noise ratio" and the "nonlinear waveform distortion" and compare it with the performance (Required-OSNR) of the optical transceiver alone, thereby enabling highly accurate assessment of transmission reachability.

[0075] Also, an optical transmission design system includes a plurality of optical transmission devices (ROADM devices 10, REP devices 40) each having an optical transmitting / receiving device 30 (FIG. 1) that relays a client signal, and an optical transmission design device 100 (FIG. 1) that evaluates the transmission reachability of a wavelength multiplexing transmission system 1000 (FIG. 1) that passes an optical signal through a plurality of optical transmission devices, wherein the optical transmission devices (ROADM devices 10, REP devices 40) (FIG. 1) include an optical amplifier 11 (FIG. 1), a spectrum monitor 14 (FIG. 1) that measures the optical level and noise level of each wavelength at the input and output sections, and a pseudo light source 15 (FIG. 1) that generates pseudo light that complements the signal waveform input to the optical amplifier 11, The optical transmission system 100 includes a noise characteristic information acquisition unit 110 (FIG. 3) that acquires noise characteristic information of optical transmission devices (ROADM device 10, REP device 40), an OSNR degradation amount calculation unit 120 (FIG. 3) that calculates the amount of optical signal-to-noise ratio degradation that occurs when an optical signal passes through the optical transmission device using the noise characteristic information acquired by the noise characteristic information acquisition unit 110, a nonlinear waveform distortion calculation unit 130 (FIG. 3) that calculates nonlinear waveform distortion of the optical transmission path, and a transmission reachability evaluation unit 140 (FIG. 3) that evaluates the transmission reachability of the wavelength multiplexing transmission system by comparing the value obtained by subtracting the nonlinear waveform distortion from the amount of optical signal-to-noise ratio degradation calculated by the OSNR degradation amount calculation unit 120 with the performance of the optical transmitting and receiving device 30 alone.

[0076] In this way, the optical transmission design system can accurately evaluate the transmission reachability during long-distance transmission assuming passage through multiple stages of ROADM devices 10 and REP devices 40, without receiving internal design information, which is generally kept secret, from suppliers of the ROADM devices 10 and REP devices 40. As a result, the transmission performance of the optical transmitting and receiving device 30 (transponder, optical transceiver) can be maximized in the existing wavelength multiplexing transmission system 1000 ( FIG. 1 ).

[0077] In the optical transmission design system (FIG. 1), the noise characteristic information acquisition unit 110 (FIG. 3) acquires noise characteristic information from a monitoring control device (NE-OpS 50) (FIGS. 1 and 3), which collects and stores data on the optical level and noise level of each wavelength acquired by the spectrum monitor 14 of each optical transmission device (ROADM device 10, REP device 40) (FIG. 1) as noise characteristic information.

[0078] In this way, the optical transmission design system can collect data on the optical level and noise level of each wavelength acquired by the spectrum monitor 14 of each optical transmission device (ROADM device 10, REP device 40) (FIG. 1) while the existing monitoring and control device (NE-OpS 50) (FIGS. 1 and 3) is monitoring and controlling the operation and maintenance of the ROADM device 10. Since the optical transmission design device 100 (FIG. 1) does not need to access each optical transmission device to acquire noise characteristic information, it is possible to simplify the device and control as well as reduce costs.

[0079] The optical transmission device (ROADM device 10, REP device 40) (Figure 1) is equipped with a spectrum monitor 14 (Figure 1) at the input and output sections that measures the optical level and noise level of each wavelength, a pseudo light source 15 (Figure 1) that generates pseudo light that complements the signal waveform input to the optical amplifier 11 (Figure 1), and the pseudo light source 15 that generates light that complements the signal waveform, keeping the input optical level of the optical amplifier 11 constant and stabilizing the amplification operation of the optical amplifier 11, regardless of the number of optical transceivers 30 applied.

[0080] By doing this, even if only a small number of optical transmission devices (ROADM devices 10, REP devices 40) are installed, the pseudo light source 15 complements the signal wavelength, making it possible to measure the signal-equivalent optical level and noise level across the entire optical band.

[0081] Note that, among the processes described in the above embodiments, all or part of the processes described as being performed automatically can be performed manually, or all or part of the processes described as being performed manually can be performed automatically using known methods. Furthermore, the processing procedures, control procedures, specific names, and information including various data and parameters shown in the above documents and drawings can be changed as desired unless otherwise specified. Furthermore, the components of each device shown in the drawings are functionally conceptual and do not necessarily have to be physically configured as shown. In other words, the specific form of distribution and integration of each device is not limited to that shown in the drawings, and all or part of the devices can be functionally or physically distributed and integrated in any unit depending on various loads, usage conditions, etc.

[0082] Furthermore, the above-described configurations, functions, processing units, processing means, etc. may be partially or entirely implemented in hardware, for example, by designing them as integrated circuits. The above-described configurations, functions, etc. may also be implemented by software that causes a processor to interpret and execute programs that implement the respective functions. Information such as programs, tables, and files that implement the respective functions may be stored in a memory, a recording device such as a hard disk or a solid-state drive (SSD), or a recording medium such as an integrated circuit (IC) card, a secure digital (SD) card, or an optical disk.

[0083] 3 General-purpose design tool 10 ROADM device (direction switching unit) (optical transmission device) 11, 11-1, 11-2 Optical amplifier 12 Wavelength / direction switching device 13, 13-1, 13-2 Optical demultiplexer 14 Spectrum monitor 15 Pseudo light source 16 Optical multiplexer 20 Wavelength signal accommodation unit 30 Optical transmitting / receiving device 40 REP device (optical amplification repeater unit) (optical transmission device) 50 NE-OpS (monitoring control device) 100 Optical transmission design device 110 Noise characteristic information acquisition unit 120 OSNR degradation amount calculation unit 130 Nonlinear waveform distortion calculation unit 140 Transmission reachability evaluation unit 1000 Wavelength multiplexing transmission system

Claims

1. An optical transmission design device for evaluating the transmission reachability of a wavelength multiplexing transmission system in which an optical signal passes through multiple stages of optical transmission equipment having optical transmitters and receivers that relay client signals and optical amplifiers, comprising: a noise characteristic information acquisition unit that acquires noise characteristic information of the optical transmission equipment; an OSNR degradation amount calculation unit that calculates the amount of optical signal-to-noise ratio degradation that occurs when the optical signal passes through the optical transmission equipment using the noise characteristic information acquired by the noise characteristic information acquisition unit; a nonlinear waveform distortion calculation unit that calculates nonlinear waveform distortion of the optical transmission path; and a transmission reachability evaluation unit that evaluates the transmission reachability of the wavelength multiplexing transmission system by comparing the value obtained by subtracting the nonlinear waveform distortion from the amount of optical signal-to-noise ratio degradation calculated by the OSNR degradation amount calculation unit with the performance of the optical transmitters and receivers alone.

2. The optical transmission design device according to claim 1, wherein the nonlinear waveform distortion calculation unit derives the nonlinear waveform distortion based on the parameters of the optical transmission line and the conditions of an optical level diagram.

3. An optical transmission design system comprising: a plurality of optical transmission devices each having an optical transmitter / receiver that relays a client signal; and an optical transmission design device that evaluates the transmission reachability of a wavelength multiplexing transmission system in which an optical signal passes through a plurality of the optical transmission devices, wherein the optical transmission devices comprise: an optical amplifier; a spectrum monitor that measures the optical level and noise level of each wavelength at an input section and an output section; and a pseudo light source that generates pseudo light that complements the signal waveform input to the optical amplifier, and the optical transmission design device comprises: a noise characteristic information acquisition section that acquires noise characteristic information of the optical transmission devices; an OSNR degradation amount calculation section that uses the noise characteristic information acquired by the noise characteristic information acquisition section to calculate the amount of optical signal-to-noise ratio degradation that occurs when an optical signal passes through the optical transmission devices; a nonlinear waveform distortion calculation section that calculates nonlinear waveform distortion of the optical transmission path; and a transmission reachability evaluation section that evaluates the transmission reachability of the wavelength multiplexing transmission system by comparing a value obtained by subtracting the nonlinear waveform distortion from the amount of optical signal-to-noise ratio degradation calculated by the OSNR degradation amount calculation section with the performance of each of the optical transmitter / receivers alone.

4. The optical transmission design system described in claim 3, characterized in that the noise characteristic information acquisition unit acquires the noise characteristic information from a monitoring control device that collects and stores the optical level and noise level data for each wavelength acquired by the spectrum monitor of each of the optical transmission devices as the noise characteristic information.

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