Network control device and optical network system

Abstract

This suppresses the degradation of transmission performance in optical paths where optical transceivers are located in an optical network at a remote location. [Solution] A network control device for controlling a plurality of devices included in an optical network, comprising: an acquisition unit that acquires first information indicating the transmission status of at least one of an optical transceiver; a first WDM (Wavelength Division Multiplexing) device connected to the optical transceiver across a first transmission path; and a second WDM device connected to the first WDM device across a second transmission path separate from the first transmission path; a calculation unit that calculates the transmission performance in the first transmission path based on the first information; and a setting change unit that changes the setting of at least one of the optical transceiver, the first WDM device, and the second WDM device based on the transmission performance in the first transmission path.

Description

[Technical Field]

[0001] This matter pertains to network control devices and optical network systems. [Background technology]

[0002] In optical communication systems, the Wavelength Division Multiplexing (WDM) method is used to transmit optical signals of various wavelengths in order to achieve high-capacity communication. In the WDM method, a WDM signal, which consists of multiple optical signals of different wavelengths, is transmitted along a single optical fiber. Optical communication systems employing the WDM method are equipped with a Wavelength Selective Switch (WSS) that controls the transmission of optical signals on a wavelength basis. The WSS has a variable bandwidth function and an attenuation adjustment function, and can control the optical attenuation of the WDM signal (see, for example, Patent Documents 1 to 5).

[0003] Furthermore, all-optical networks utilizing the WDM method are also known. In optical communication systems that constitute an all-optical network, multiple transmitting terminals and multiple receiving terminals are connected end-to-end by light without the need for photoelectric conversion. Optical signals transmitted from a transmitting terminal are input to one of the relay nodes, where the path is switched according to wavelength and then forwarded to the receiving terminal. It is also known that the relay node function can be added to a ROADM (Reconfigurable Optical Add / Drop Multiplexer) device (see, for example, Patent Document 6). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2019 / 188633 [Patent Document 2] International Publication No. 2019 / 107471 [Patent Document 3] International Publication No. 2023 / 181388 [Patent Document 4] U.S. Patent Application Publication No. 2016 / 0164597 [Patent Document 5] U.S. Patent Application Publication No. 2024 / 0259096 Specification [Patent Document 6] International Publication No. 2023 / 112326 [Overview of the project] [Problems that the invention aims to solve]

[0005] Incidentally, optical transceivers (such as transponders) that include an optical transmitter that transmits optical signals (hereinafter referred to as signal light) and an optical receiver that receives signal light may be connected to or installed in ROADM equipment. Optical transceivers and ROADM equipment are often located within the same optical network managed by the telecommunications carrier.

[0006] On the other hand, there are also considerations for placing optical transceivers within the communication network managed by the telecommunications carrier's end users, as well as extending the optical network where ROADM devices are located to include the area where the optical transceivers are placed. The telecommunications carrier's end users are businesses that utilize the communication services provided by the telecommunications carrier as their final customers.

[0007] Optical networks managed by telecommunications carriers and communication networks managed by end users are often located far apart. When optical transceivers are placed remotely, far apart from ROADM devices, noise generated in the transmission path of the separated section may degrade the transmission performance of the optical path.

[0008] Therefore, one objective is to provide a network control device and an optical network system that suppress the degradation of transmission performance of optical paths where optical transceivers are located in an optical network at a remote location. [Means for solving the problem]

[0009] In one embodiment, a network control device is a network control device that controls a plurality of devices included in an optical network, and includes an optical transceiver, a first WDM device connected to the optical transceiver with a first transmission path interposed therebetween, and a second WDM device connected to the first WDM device with a second transmission path different from the first transmission path interposed therebetween. The network control device further includes an acquisition unit that acquires first information indicating respective transmission states from at least one of the above components, a calculation unit that calculates transmission performance in the first transmission path based on the first information, and a setting change unit that changes settings of at least one of the optical transceiver, the first WDM device, and the second WDM device based on the transmission performance in the first transmission path.

Advantages of the Invention

[0010] It is possible to suppress a decrease in transmission performance of an optical path accommodated in an optical network in which an optical transceiver is remotely arranged.

Brief Description of the Drawings

[0011] [Figure 1] This is an example of an optical network. [Figure 2] This is a diagram for explaining an example of a remote transponder. [Figure 3] This is a diagram for explaining an example of a first photonic gateway and a first ROADM device. [Figure 4] This is a diagram for explaining an example of a second ROADM device. [Figure 5] This is a diagram for explaining an example of an Nth photonic gateway and an Nth ROADM device. [Figure 6] This is a diagram for explaining another example of a remote transponder. [Figure 7] This is a diagram for explaining an example of the functional configuration of an NMS. [Figure 8] (a) is a diagram for explaining an example of a slot width before setting change. (b) is a diagram for explaining an example of a slot width after setting change. [Figure 9] This is a flowchart showing an example of the operation of an NMS. [Figure 10] This figure illustrates a comparative example according to the first embodiment. [Figure 11] This is a diagram illustrating an embodiment according to the first embodiment. [Figure 12] This is a diagram illustrating another embodiment according to the first embodiment. [Figure 13] This figure illustrates an example of the effects of the first transmission model #1 according to the first embodiment. [Figure 14] This figure illustrates an example of the effects of the second transmission model #2 according to the first embodiment. [Figure 15] This figure illustrates an example of the effects of the third transmission model #3 according to the first embodiment. [Figure 16] This is a diagram illustrating an example of a second embodiment. [Figure 17] This is a diagram illustrating an example of the third embodiment. [Figure 18] This figure illustrates an example of the fourth embodiment. [Modes for carrying out the invention]

[0012] The following will explain the implementation of this project with reference to the drawings.

[0013] (First Embodiment) As shown in Figure 1, the optical network NW comprises multiple remote transponders (indicated as R-TRPN in Figure 1) RS, RG, multiple photonic gateways (indicated as Ph-GW in Figure 1) P1, P3, and multiple ROADM devices R1, R2, ..., R3.

[0014] Remote transponders RS and RG are both examples of optical transceivers. A combination of photonic gateway P1 and ROADM device R1, or a combination of photonic gateway P3 and ROADM device R3, are both examples of first WDM devices. ROADM device R2 is an example of a second WDM device. The devices installed in station buildings B0 and B4, described later, may also be examples of optical transceivers. The devices installed in station buildings B1 and B3, described later, may also be examples of first WDM devices. The device installed in station building B2, described later, may also be an example of a second WDM device. Photonic gateways P1 and P3 may be the first optical devices, or ROADM devices R1 and R3 may be the second optical devices.

[0015] Remote transponders RS and RG are installed at the terminal stations of the optical network NW. Photonic gateways P1 and P3 and ROADM devices R1, R2, ..., R3 are installed at non-terminal stations (e.g., relay stations and switching stations) of the optical network NW, excluding the terminal stations. The terminal stations are located remotely from the non-terminal stations.

[0016] The remote transponder RS ​​is installed in building B0, which is located at the terminal station. Building B0 is the building of an end-user of the telecommunications carrier. Building B0 may also be the building of the operator that runs the data center. As will be explained in detail later, the remote transponder RS ​​can individually transmit multiple remote signal lights with different wavelengths. For this reason, building B0 corresponds to the starting point of the remote signal lights.

[0017] The photonic gateway P1 and ROADM device R1 are installed in building B1, which is located at a non-end station. Building B1 is the 1st location relative to building B0. The ROADM device R2 is installed in building B2, which is located at a non-end station. Building B2 is the 2nd location relative to building B0. The ROADM device R3 and photonic gateway P3 are installed in building B3, which is located at a non-end station. Building B3 is the Nth location relative to building B0 (where N is a natural number greater than or equal to 3). Buildings B1, B2, and B3 are all buildings of a telecommunications carrier.

[0018] The remote transponder RG is installed in station building B4, which is located at the terminal station. Station building B4 is the station of the end user or operator mentioned above. The remote transponder RG can individually receive multiple remote signal lights with different wavelengths. Therefore, station building B4 corresponds to the destination of the remote signal lights.

[0019] Thus, in the optical network NW according to this embodiment, remote transponders RS and RG installed in the end-user's central offices B0 and B4, which are different from the telecommunications carrier, are used. In other words, the remote transponders RS and RG partially belong to the end-user's communication network. For this reason, the remote transponders RS and RG are managed by the end-user, not the telecommunications carrier. On the other hand, the photonic gateways P1 and P3 and the ROADM devices R1, R2, ..., R3 are managed by the telecommunications carrier.

[0020] The remote transponder RS ​​and the photonic gateway P1 are connected to each other by transmission path 50. ROADM devices R1 and R2 are connected to each other by transmission path 51. ROADM devices R2, ..., R3 are connected to each other by transmission path 52. The photonic gateway P3 and the remote transponder RG are connected to each other by transmission path 53. Transmission paths 50, 51, 52, and 53 all contain optical fibers. Transmission paths 50 and 53 are examples of first transmission paths, and transmission paths 51 and 52 are examples of second transmission paths. For example, transmission paths 50, 51, 52, and 53 contain optical fibers such as single-mode optical fibers used for long-distance transmission. Optical In-Line Amplifier Equipment (ILAs) may be installed in the middle of each of the transmission paths 50, 51, 52, and 53.

[0021] On the other hand, since both the photonic gateway P1 and the ROADM device R1 are installed in the central office building B1, they are connected to each other by optical fiber 54. Since both the ROADM device R3 and the photonic gateway P3 are installed in the central office building B3, they are connected to each other by optical fiber 55. Optical fibers 54 and 55 are, for example, multimode optical fibers used for short-distance transmission. Thus, optical fibers 54 and 55 are of a different type from the optical fibers contained within the transmission lines 50, 51, 52, and 53.

[0022] In this embodiment, WDM light propagates between ROADM devices R1, R2, ..., R3. WDM light is a signal light that is multiplexed by combining multiple remote signal lights of different wavelengths. For this reason, the section including ROADM devices R1, R2, ..., R3 is called the WDM transmission section. On the other hand, the section including transmission path 50 and photonic gateway P1, and the section including transmission path 53 and photonic gateway P3 are called remote sections, respectively. The remote sections partially include remote transponders RS and RG, but may also include them entirely. Note that the remote section is an example of the first section, and the WDM transmission section is an example of the second section.

[0023] The photonic gateways P1 and P3, and the ROADM devices R1, R2, ..., R3 are all electrically connected to an NMS (Network Management System) 100 managed and operated by a telecommunications carrier. The NMS 100 is an example of a network control device. The NMS 100 controls the operation of the photonic gateways P1 and ROADM devices R1, etc., via the communication network 150. The communication network 150 is, for example, a DCN (Data Communication Network) and includes at least one of a LAN (Local Area Network), a WAN (Wide Area Network), and the Internet.

[0024] The remote transponders RS and RG are not directly connected to the communication network 150. As will be explained in detail later, the NMS100 acquires various information indicating the transmission status from the photonic gateway P1, ROADM device R1, and other devices. Once the NMS100 acquires this information, it executes controls on the ROADM device R1 and other devices to improve the transmission performance of the optical network NW based on the acquired information. This improvement in transmission performance enables an extension of the transmission distance in the optical network NW.

[0025] Furthermore, the optical network system is realized by the remote transponder RS, photonic gateway P1, ROADM device R1, and NMS100. Alternatively, the optical network system may be realized by the ROADM device R3, photonic gateway P3, remote transponder RG, and NMS100.

[0026] Refer to Figures 2 through 6 to describe the details of the remote transponders RS and RG, the photonic gateways P1 and P3, and the ROADM devices R1, R2, ..., R3.

[0027] First, the remote transponder RS ​​will be described with reference to Figure 2. The remote transponder RS ​​comprises multiple optical transmitters 5A, 5B, ..., 5C, an optical filter 5D, an OSC communication unit 5E, and a control unit 5F. Although not shown, the remote transponder RS ​​may also include multiple optical receivers.

[0028] Optical transmitter 5A transmits a single-wavelength remote signal light L1 based on control by control unit 5F. Optical transmitter 5B transmits a single-wavelength remote signal light L2 based on control by control unit 5F. Optical transmitter 5C transmits a single-wavelength remote signal light L3 based on control by control unit 5F. Optical transmitters not shown, other than optical transmitters 5A, 5B, and 5C, also transmit remote signal light in the same way as optical transmitters 5A, 5B, and 5C. The single wavelengths of the remote signal lights L1, L2, L3, etc. transmitted by optical transmitters 5A, 5B, ..., 5C are different from each other.

[0029] The optical filter 5D includes an optical coupler, such as a multiplexing coupler. Therefore, when remote signal lights L1, L2, L3, etc. are input to the optical filter 5D, they are combined by the optical filter 5D and output from the optical filter 5D as remote multiplexed light Lr. As a result, the remote multiplexed light Lr is output from the remote transponder RS ​​to the transmission line 50.

[0030] For example, if one of the remote signal lights L1, L2, or L3 is input to the optical filter 5D, one of the input remote signal lights L1, L2, or L3 will be output from the optical filter 5D. In this case, one of the remote signal lights L1, L2, or L3 will be output as a remote multiplexed light Lr from the remote transponder RS ​​to the transmission path 50.

[0031] The OSC communication unit 5E transmits OSC (Optical Supervisory Channel) optical Lo1 based on control by the control unit 5F. OSC optical Lo1 includes the transmitter output power, which is the sum of the output powers of, for example, optical transmitters 5A, 5B, ..., 5C. The transmitter output power can also be said to be the power at which the remote transponder RS ​​inputs remote multiplexed optical Lr into the transmission path 50. The OSC communication unit 5E is connected to the optical path through which the remote multiplexed optical Lr propagates via the OSC coupler 5G. As a result, OSC optical Lo1 is output from the remote transponder RS ​​to the transmission path 50. As will be described in detail later, when OSC optical Lo1 is input to the remote transponder RS, the OSC communication unit 5E can also receive OSC optical Lo1.

[0032] The control unit 5F is electrically connected to the optical transmitters 5A, 5B, ..., 5C and the OSC communication unit 5E. The control unit 5F can control the operation of the optical transmitters 5A, 5B, ..., 5C and the OSC communication unit 5E. For example, the control unit 5F can control optical transmitter 5A independently to cause it to transmit remote signal light L1 individually. The control unit 5F can control the OSC communication unit 5E to cause it to transmit OSC light Lo1. Based on the OSC light Lo1 received by the OSC communication unit 5E, the control unit 5F can change the symbol rate settings of the optical transmitters 5A, 5B, ..., 5C.

[0033] Next, with reference to Figure 3, the photonic gateway P1 and the ROADM device R1 will be described.

[0034] First, let's describe the photonic gateway P1. The photonic gateway P1 comprises an OSC communication unit 10A, a PD (Photo Diode) 10B, a receiving amplifier 10C, an optical filter 10D, and a control unit 10E. The receiving amplifier 10C is an example of a first amplifier.

[0035] The OSC communication unit 10A receives the OSC optical Lo1 propagated through the transmission line 50 via the OSC splitter 10F. Since the OSC optical Lo1 includes the transmitter output power described above, the OSC communication unit 10A can output the transmitter output power to the control unit 10E. The OSC communication unit 10A can also transmit the OSC optical Lo1 based on the control by the control unit 10E. The OSC optical Lo1 includes, for example, an instruction to change the symbol rate setting. The OSC optical Lo1 transmitted by the OSC communication unit 10A is output from the photonic gateway P1 to the transmission line 50. As a result, the OSC communication unit 5E of the remote transponder RS ​​can receive the OSC optical Lo1.

[0036] PD10B is connected to the optical path through which the remote multiplexed light Lr propagates via a branch coupler 10G. This allows PD10B to detect the optical power of the remote multiplexed light Lr. PD10B is positioned upstream or before the receiving amplifier 10C. Therefore, when PD10B detects the optical power of the remote multiplexed light Lr, it can output the optical power of the remote multiplexed light Lr to the control unit 10E as the amplifier input power of the receiving amplifier 10C.

[0037] The receiving amplifier 10C is an optical amplifier, for example, an EDFA (Erbium Doped Fiber Amplifier). The receiving amplifier 10C receives and amplifies the remote multiplexed light Lr. After amplifying the remote multiplexed light Lr, the receiving amplifier 10C outputs the remote multiplexed light Lr to the optical filter 10D.

[0038] The optical filter 10D includes optical couplers such as demultiplexing couplers. Therefore, when the remote signal lights L1, L2, and L3 are combined to form a remote combined light Lr which is input to the optical filter 10D, the remote combined light Lr is demultiplexed by the optical filter 10D, and the remote signal lights L1, L2, and L3 are output individually from the optical filter 10D. For example, when the remote signal light L1 is input to the optical filter 10D as a remote combined light Lr, the remote signal light L1 is output individually from the optical filter 10D.

[0039] The control unit 10E is electrically connected to the OSC communication unit 10A and the PD 10B. The control unit 10E can control the operation of the OSC communication unit 10A. For example, the control unit 10E can control the OSC communication unit 10A to transmit OSC optical Lo1. When the control unit 10E receives the transmitter output power output from the OSC communication unit 10A and the amplifier input power output from the PD 10B, it can output the transmitter output power and amplifier input power to the NMS 100.

[0040] Next, the ROADM device R1 will be described. The ROADM device R1 comprises multiple optical transmitters 15A, 15B, ..., 15C, a multiplexer (indicated as MUX in Figure 3, and similarly in subsequent figures) 15D, a WSS 15E, a WDM amplifier 15F, PDs 15G, 15H, and a control unit 15K.

[0041] Optical transmitter 15A transmits a single-wavelength local signal light L4 based on control by control unit 15K. Optical transmitter 15B transmits a single-wavelength local signal light L5 based on control by control unit 15K. Optical transmitter 15C transmits a single-wavelength local signal light L6 based on control by control unit 15K. Optical transmitters not shown, other than optical transmitters 15A, 15B, and 15C, also transmit local signal light in the same way as optical transmitters 15A, 15B, and 15C. The single wavelengths of local signal light L4, L5, L6, etc. transmitted by each of the optical transmitters 15A, 15B, ..., 15C are different from each other.

[0042] The multiplexer 15D combines the remote signal lights L1, L2, L3 and the local signal lights L4, L5, L6. That is, the multiplexer 15D generates WDM light Lw by combining the remote signal lights L1, L2, L3 and the local signal lights L4, L5, L6. Once the multiplexer 15D generates WDM light Lw, it outputs the WDM light Lw downstream of the optical network NW. Note that the remote combined light Lr may contain the remote signal light L1 alone, and the optical transmitter 15A may transmit the local signal light L5, which has a different wavelength from the remote signal light L1, alone. In this case, the multiplexer 15D generates and outputs WDM light Lw by combining the remote signal light L1 and the local signal light L5.

[0043] The WSS15E increases the optical power of the WDM optical light Lw based on control by the control unit 15K. For example, when a WDM optical light Lw, which is a combination of the remote signal light L1 and the local signal light L5, is input to the WSS15E, the WSS15E increases the optical power of the remote signal light L1 while maintaining the optical power of the local signal light L5, based on the control amount of the WSS15E controlled by the control unit 15K. As a result, the amount of noise generated for the remote signal light L1 in the transmission line 50 laid in the remote section is relatively reduced.

[0044] To maintain the optical power of the local signal light L5 while increasing the optical power of the remote signal light L1, the optical power of the WDM light Lw increases. Consequently, the input power of the WDM light Lw to the WDM amplifier 15F, which is installed as a post-amplifier after the WSS15E, increases. As a result, even when the WDM light Lw propagates through the transmission lines 51 and 52 laid in the WDM transmission section, the noise generated in the WDM transmission section is reduced compared to when the optical power of the remote signal light L1 is not increased.

[0045] Furthermore, the WSS15E may include a multiplexer 15D. Also, as will be described in detail later, by the control unit 15K changing the slot width of the WSS15E's slots (e.g., adjusting or expanding it), the WSS15E can increase the optical power of the remote signal light L1 while maintaining the optical power of the local signal light L5. In other words, under the ALC (Automatic Level Control) control described later, the WSS15E can increase the optical power of the channel being modified without affecting the optical power of channels other than the channel being modified. For example, when the slot width is expanded, the maximum number of channels of WDM optical light Lw output from the WSS15E to the WDM amplifier 15F is limited.

[0046] The WDM amplifier 15F is an optical amplifier that includes, for example, an EDFA. The WDM amplifier 15F receives WDM optical light Lw and amplifies the WDM optical light Lw in ALC mode. ALC is sometimes called APC (Automatic Power Control) or AGC (Automatic Gain Control). After amplifying the WDM optical light Lw, the WDM amplifier 15F outputs the WDM optical light Lw to the transmission line 51.

[0047] PD15G is connected to the optical path through which the WDM optical light Lw propagates via a branch coupler 15I. This allows PD15G to detect the optical power of the WDM optical light Lw. The branch coupler 15I is located upstream or before the WDM amplifier 15F. Therefore, when PD15G detects the optical power of the WDM optical light Lw, it can output the optical power of the WDM optical light Lw to the control unit 15K as the amplifier input power of the WDM amplifier 15F.

[0048] PD15H is connected to the optical path through which the WDM optical light Lw propagates via a branch coupler 15J. This allows PD15H to detect the optical power of the WDM optical light Lw. The branch coupler 15J is located downstream or after the WDM amplifier 15F. Therefore, when PD15H detects the optical power of the WDM optical light Lw, it can output the optical power of the WDM optical light Lw to the control unit 15K as the amplifier output power of the WDM amplifier 15F.

[0049] The control unit 15K is electrically connected to the optical transmitters 15A, 15B, ..., 15C, WSS15E, and PD15G, 15H. The control unit 15K can control the operation of the optical transmitters 15A, 15B, ..., 15C and WSS15E. For example, the control unit 15K can independently control optical transmitter 15B to cause it to transmit local signal light L5. The control unit 15K can control WSS15E to change its slot width. The control unit 15K can output the optical power of the WDM light Lw detected by PD15G, 15H to the NMS100 as amplifier input power and amplifier output power, respectively.

[0050] Next, the ROADM device R2 will be described with reference to Figure 4. The ROADM device R2 comprises multiple optical transmitters 25A, ..., 25C, multiple optical receivers 25D, ..., 25F, a multiplexer 25G, and a demultiplexer (denoted as DEMUX in Figure 4 and similarly in subsequent figures) 25H. The ROADM device R2 also comprises WSS 25I, 25J, WDM amplifiers 25K, 25L, PDs 25M, 25N, 25P, 25Q, and a control unit 25R.

[0051] The WDM amplifier 25L is, for example, an optical amplifier including an EDFA. As a preamplifier placed before the WSS25J, the WDM amplifier 25L receives the WDM optical signal Lw input to the ROADM device R2 and amplifies the WDM optical signal Lw in ALC mode. After amplifying the WDM optical signal Lw, the WDM amplifier 25L outputs the signal Lw downstream of the WDM amplifier 25L.

[0052] The PD25P is connected to the optical path through which the WDM optical fiber Lw propagates via a branch coupler 25U. This allows the PD25P to detect the optical power of the WDM optical fiber Lw. The branch coupler 25U is installed upstream or before the WDM amplifier 25L. Therefore, when the PD25P detects the optical power of the WDM optical fiber Lw, it can output the optical power of the WDM optical fiber Lw to the control unit 25R as the amplifier input power of the WDM amplifier 25L.

[0053] PD25Q is connected to the optical path through which the WDM optical light Lw propagates via a branching coupler 25V. This allows PD25Q to detect the optical power of the WDM optical light Lw. The branching coupler 25V is located downstream or after the WDM amplifier 25L. Therefore, when PD25Q detects the optical power of the WDM optical light Lw, it can output the optical power of the WDM optical light Lw to the control unit 25R as the amplifier output power of the WDM amplifier 25L.

[0054] The WSS25J increases the optical power of the WDM optical light Lw based on control by the control unit 25R. For example, when the WSS25J receives a WDM optical light Lw obtained by combining the remote signal light L1 and the local signal light L5, it increases the optical power of the remote signal light L1 while maintaining the optical power of the local signal light L5, based on control by the control unit 25R. This relatively reduces the amount of noise generated for the remote signal light L1 in the transmission line 50 laid in the remote section. As a result of increasing the optical power of the remote signal light L1 while maintaining the optical power of the local signal light L5, the optical power of the WDM optical light Lw increases.

[0055] The demultiplexer 25H splits the WDM optical light Lw output from the WSS25J into, for example, remote signal light L1, L2, L3 and local signal light L4, L5, L6. After splitting the WDM optical light Lw, the demultiplexer 25H outputs, for example, the remote signal light L1, L2 and local signal light L4 downstream of the demultiplexer 25H, and outputs the remote signal light L3 and local signal light L6, etc., to the optical receivers 25D and 25F.

[0056] Optical receiver 25D receives remote signal light L3. Optical receiver 25D may also receive remote signal light L1, L2, etc. Optical receiver 25F receives local signal light L6. Optical receiver 25F may also receive local signal light L4, L5. Optical receivers not shown, other than optical receivers 25D and 25F, also receive remote signal light or local signal light in the same way as optical receivers 25D and 25F. Optical receivers 25D, 25F, etc. convert the remote signal light L3 and local signal light L6, etc. into electrical digital signals. The control unit 25R measures the signal quality of the remote signal light L3 and local signal light L6, etc., based on the digital signals.

[0057] Optical transmitter 25A transmits a single-wavelength local signal light L7 based on control by control unit 25R. Optical transmitter 25C transmits a single-wavelength local signal light L8 based on control by control unit 25R. Optical transmitters not shown, other than optical transmitters 25A and 25C, also transmit local signal light in the same way as optical transmitters 25A and 25C. The single wavelengths of local signal lights L7, L8, etc. transmitted by optical transmitters 25A, ..., 25C are different from each other.

[0058] Multiplexer 25G combines the remote signal lights L1 and L2 with the local signal lights L4, L5, L7, and L8. That is, Multiplexer 25G generates WDM optical light Lw by combining the remote signal lights L1 and L2 with the local signal lights L4, L5, L7, and L8. Once Multiplexer 25G generates WDM optical light Lw, it outputs it downstream to the optical network NW. Note that Multiplexer 25G may also generate and output WDM optical light Lw by combining the remote signal light L1 and the local signal light L5.

[0059] Similar to the WSS15E, the WSS25I increases the optical power of the WDM optical signal Lw output from the multiplexer 25G based on control by the control unit 25R. For example, when a WDM optical signal Lw, which is a combination of the remote signal signal L1 and the local signal signal L5, is input to the WSS25I, the control unit 15K controls the WSS25I to maintain the optical power of the local signal signal L5 while increasing the optical power of the remote signal signal L1. This relatively reduces the amount of noise generated for the remote signal signal L1 in the transmission line 50 laid in the remote section.

[0060] In order to maintain the optical power of the local signal light L5 while increasing the optical power of the remote signal light L1, the optical power of the WDM light Lw is increased. Consequently, the input power of the WDM light Lw to the WDM amplifier 25K, which is provided as a post-amplifier after the WSS25I, is increased. As a result, even when the WDM light Lw propagates through the transmission path 52 laid in the WDM transmission section, the noise generated in the WDM transmission section is reduced compared to when the optical power of the remote signal light L1 is not increased.

[0061] The WDM amplifier 25K is, for example, an optical amplifier including an EDFA. The WDM amplifier 25K receives the WDM optical light Lw and amplifies the WDM optical light Lw in ALC mode. After amplifying the WDM optical light Lw, the WDM amplifier 25K outputs the WDM optical light Lw to the transmission line 52.

[0062] The PD25M is connected to the optical path through which the WDM optical light Lw propagates via a branch coupler 25S. This allows the PD25M to detect the optical power of the WDM optical light Lw. The branch coupler 25S is installed upstream or before the WDM amplifier 25K. Therefore, when the PD25M detects the optical power of the WDM optical light Lw, it can output the optical power of the WDM optical light Lw to the control unit 25R as the amplifier input power of the WDM amplifier 25K.

[0063] PD25N is connected to the optical path through which the WDM optical light Lw propagates via a branch coupler 25T. This allows PD25N to detect the optical power of the WDM optical light Lw. The branch coupler 25N is located downstream or after the WDM amplifier 25K. Therefore, when PD25N detects the optical power of the WDM optical light Lw, it can output the optical power of the WDM optical light Lw to the control unit 25R as the amplifier output power of the WDM amplifier 25K.

[0064] The control unit 25R is electrically connected to the optical transmitters 25A, ..., 25C, the optical receivers 25D, ..., 25F, WSS25I, 25J, and PD25M, 25N, 25P, 25Q. The control unit 25R can control the operation of the optical transmitters 25A, ..., 25C and WSS25I, 25J. For example, the control unit 25R can control the optical transmitter 25C independently to cause it to transmit local signal light L8. The control unit 25R can control WSS25I, 25J to change the slot width of WSS25I, 25J. The control unit 25R can output the optical power of the WDM light Lw detected by PD25M, 25N, 25P, 25Q to the NMS100 as amplifier input power and amplifier output power, respectively.

[0065] Next, with reference to Figure 5, the ROADM device R3 and the photonic gateway P3 will be described.

[0066] First, let's describe the ROADM device R3. The ROADM device R3 comprises multiple optical receivers 35D, 35E, ..., 35F, a demultiplexer 35H, a WSS 35J, a WDM amplifier 35L, PDs 35P, 35Q, and a control unit 35R.

[0067] The WDM amplifier 35L is, for example, an optical amplifier including an EDFA. As a preamplifier placed before the WSS35J, the WDM amplifier 35L receives the WDM optical signal Lw input to the ROADM device R3 and amplifies the WDM optical signal Lw in ALC mode. After amplifying the WDM optical signal Lw, the WDM amplifier 35L outputs the signal Lw downstream of the WDM amplifier 35L.

[0068] The PD35P is connected to the optical path through which the WDM optical light Lw propagates via a branch coupler 35U. This allows the PD35P to detect the optical power of the WDM optical light Lw. The branch coupler 35U is installed upstream or before the WDM amplifier 35L. Therefore, when the PD35P detects the optical power of the WDM optical light Lw, it can output the optical power of the WDM optical light Lw to the control unit 35R as the amplifier input power of the WDM amplifier 35L.

[0069] PD35Q is connected to the optical path through which the WDM optical light Lw propagates via a branch coupler 35V. This allows PD35Q to detect the optical power of the WDM optical light Lw. The branch coupler 35V is located downstream or after the WDM amplifier 35L. Therefore, when PD35Q detects the optical power of the WDM optical light Lw, it can output the optical power of the WDM optical light Lw to the control unit 35R as the amplifier output power of the WDM amplifier 35L.

[0070] Similar to the WSS15E, the WSS35J increases the optical power of the WDM optical light Lw based on control by the control unit 35R. For example, when a WDM optical light Lw, which is a combination of the remote signal light L1 and the local signal light L5, is input to the WSS35J, the control unit 35R controls the optical power of the remote signal light L1 while maintaining the optical power of the local signal light L5. This relatively reduces the amount of noise generated for the remote signal light L1 in the transmission line 50 laid in the remote section. Because the optical power of the remote signal light L1 is increased while maintaining the optical power of the local signal light L5, the optical power of the WDM optical light Lw is increased as a result.

[0071] Demultiplexer 35H splits the WDM optical signal Lw output from WSS35J into remote signal signals L1, L2 and local signal signals L4, L5, L7, L8. After splitting the WDM optical signal Lw, demultiplexer 35H outputs, for example, remote signal signal L2 and local signal signals L4, L7 downstream of demultiplexer 25H, and outputs remote signal signal L1 and local signal signals L5, L8, etc. to optical receivers 35D, 35E, ..., 35F.

[0072] Optical receiver 35D receives remote signal light L1. Optical receiver 35D may also receive remote signal light L2. Optical receiver 35E receives local signal light L5. Optical receiver 35F may also receive local signal light L4. Optical receiver 35F receives local signal light L8. Optical receiver 35F may also receive local signal light L7. Optical receivers not shown, excluding optical receivers 35D, 35E, ..., 35F, also receive remote signal light or local signal light in the same way as optical receivers 35D, 35E, ..., 35F. Optical receivers 35D, 35E, ..., 35F, etc., convert the remote signal light L1 and local signal lights L5, L8, etc. into electrical digital signals. The control unit 35R measures the signal quality of the remote signal light L1 and local signal lights L5, L8, etc., based on the digital signals.

[0073] The control unit 35R is electrically connected to the optical receivers 35D, 35E, ..., 35F, WSS35J, and PD35P, 35Q. The control unit 35R can control the operation of WSS35J. For example, the control unit 35R can control WSS35J to change its slot width. The control unit 35R can output the optical power of the WDM optical Lw detected by PD35P, 35Q to the NMS100 as amplifier input power and amplifier output power, respectively.

[0074] Next, the photonic gateway P3 will be described. The photonic gateway P3 comprises an OSC communication unit 30A, PDs 30B and 30H, a transmitting amplifier 30C, an optical filter 30D, and a control unit 30E. The transmitting amplifier 30C is an example of a second amplifier. In this embodiment, the photonic gateway P3 does not necessarily have to include the OSC communication unit 30A.

[0075] The optical filter 30D includes an optical coupler, such as a multiplexing coupler. Therefore, when the remote signal light L2 and local signal lights L4 and L7 are individually input to the optical filter 30D, the remote signal light L2 and local signal lights L4 and L7 are combined by the optical filter 30D, and the remote multiplexed light Lr is output from the optical filter 30D. For example, when the remote signal light L1 is input to the optical filter 30D alone, the remote signal light L1 is output from the optical filter 30D as the remote multiplexed light Lr.

[0076] The transmitting amplifier 30C is, for example, an optical amplifier including an EDFA. The transmitting amplifier 30C amplifies the remote multiplexed optical light Lr. After amplifying the remote multiplexed optical light Lr, the transmitting amplifier 30C outputs the remote multiplexed optical light Lr to the transmission path 53 and transmits it.

[0077] PD30B is connected to the optical path through which the remote multiplexed light Lr propagates via a branch coupler 30G. This allows PD30B to detect the optical power of the remote multiplexed light Lr. PD30B is positioned upstream or before the transmitting amplifier 30C. Therefore, when PD30B detects the optical power of the remote multiplexed light Lr, it can output the optical power of the remote multiplexed light Lr to the control unit 30E as the amplifier input power of the transmitting amplifier 30C.

[0078] PD30H is connected to the optical path through which the remote multiplexed light Lr propagates via a branch coupler 30I. This allows PD30H to detect the optical power of the remote multiplexed light Lr. PD30H is positioned downstream or after the transmitting amplifier 30C. Therefore, when PD30H detects the optical power of the remote multiplexed light Lr, it can output the optical power of the remote multiplexed light Lr to the control unit 30E as the amplifier output power of the transmitting amplifier 30C.

[0079] The OSC communication unit 30A can receive the OSC optical Lo2 that has propagated along the transmission path 53 via the OSC splitter 30F. As will be described in detail later, the OSC optical Lo2 is output from the remote transponder RG.

[0080] The control unit 30E is electrically connected to the OSC communication unit 30A and PD30B and 30H. For example, when the control unit 30E receives the amplifier input power and amplifier output power output from PD30B and 30H, it can output the amplifier input power and amplifier output power to the NMS100.

[0081] Next, the remote transponder RG will be described with reference to Figure 6. The remote transponder RG comprises a plurality of optical receivers 9A, 9B, ..., 9C, an optical filter 9D, an OSC communication unit 9E, and a control unit 9F. Although not shown, the remote transponder RG may also include a plurality of optical transmitters.

[0082] The OSC communication unit 9E transmits OSC optical Lo2 based on control by the control unit 9F. The OSC communication unit 9E is connected to the optical path through which the remote multiplexed optical Lr propagates via the OSC coupler 9G. As a result, the OSC optical Lo2 is output from the remote transponder RG to the transmission path 53.

[0083] The optical filter 9D includes optical couplers, such as demultiplexing couplers. Therefore, when the remote multiplexed light Lr is input to the optical filter 9D, the remote multiplexed light Lr is demultiplexed by the optical filter 9D, and the remote signal light L2 and local signal lights L4 and L7 are output from the optical filter 9D.

[0084] Optical receiver 9A receives local signal light L4 output from optical filter 9D. Optical receiver 9B receives remote signal light L2 output from optical filter 9D. Optical receiver 9C receives local signal light L7 output from optical filter 9D. Optical receivers not shown, other than optical receivers 9A, 9B, and 9C, also receive remote signal light in the same way as optical receivers 9A, 9B, and 9C. Optical receivers 9A, 9B, 9C, etc., convert the remote signal light L2 and local signal lights L7, L8, etc. into electrical digital signals.

[0085] The control unit 9F is electrically connected to the optical receivers 9A, 9B, ..., 9C and the OSC communication unit 9E. The control unit 9F can control the operation of the OSC communication unit 9E. For example, the control unit 9F can control the OSC communication unit 9E to transmit OSC optical Lo2. Based on the digital signals converted by the optical receivers 9A, 9B, 9C, the control unit 9F measures the signal quality of remote signal light L2 and local signal lights L4, L7, etc.

[0086] Referring to Figures 7 and 8, the functional configuration of the NMS100 will be explained along with its hardware configuration. Note that the control units 5F, 9F, 10E, 15K, 25R, 30E, and 35R have essentially the same hardware configuration as the NMS100, so a detailed explanation will be omitted.

[0087] The NMS100 is implemented using, for example, a processor such as a CPU (Central Processing Unit) and memory such as RAM (Random Access Memory) and ROM (Read Only Memory). The control program stored in ROM is temporarily stored in RAM by the CPU. By executing the stored control program, the CPU implements the various functions described later. The control program should conform to the flowchart described later. The NMS100 may also be implemented using hardware circuits such as FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit).

[0088] As shown in Figure 7, the NMS100 comprises a storage unit 110, a processing unit 120, an input unit 130, and an output unit 140. The storage unit 110 can be implemented by the memory described above. The processing unit 120 can be implemented by the processor described above. The input unit 130 and the output unit 140 can be implemented by a communication interface (I / F).

[0089] The storage unit 110, the processing unit 120, the input unit 130, and the output unit 140 are connected to each other. The storage unit 110 includes an optical path setting DB (Data Base) 111. The processing unit 120 includes a first acquisition unit 121, a first calculation unit 122, a second acquisition unit 123, a second calculation unit 124, an increase amount calculation unit 125, a setting value calculation unit 126, and a setting change unit 127. The first acquisition unit 121 and the second acquisition unit 123 are examples of acquisition units. The first calculation unit 122, the second calculation unit 124, the increase amount calculation unit 125, and the setting value calculation unit 126 are examples of calculation units.

[0090] The optical path setting DB111 stores calculation basis information used when calculating the noise level of noise generated in remote sections and WDM transmission sections. This calculation basis information includes, for example, remote determination information indicating whether the optical path includes a remote section, information representing the basic control target value of the optical power of the signal light that can be selected according to the symbol rate, and information regarding the basic slot width determined from the symbol rate. The calculation basis information also includes the noise coefficient of the optical amplifier (so-called noise figure) and the nonlinear noise coefficient that can be selected according to the type of optical fiber contained in transmission paths 50, 51, 52, and 53.

[0091] The first acquisition unit 121 acquires power information for the remote section from the control unit 10E of the photonic gateway P1 and the control unit 30E of the photonic gateway P3, respectively. The power information indicates the transmission status. For example, the first acquisition unit 121 acquires the transmitter output power and the amplifier input power of the receiving amplifier 10C from the control unit 10E as power information for the remote section. In addition, the first acquisition unit 121 acquires the amplifier input power and amplifier output power of the transmitting amplifier 30C from the control unit 30E as power information for the remote section.

[0092] The first calculation unit 122 calculates the amount of noise generated in the remote section based on the power information of the remote section. More specifically, the first calculation unit 122 calculates the noise level (Noise / Signal) of the optical path including the remote section based on the power information of the remote section and, for example, the following formula (1). Remote Calculate.

number

[0093] Here, in the above formula (1), 1 / GSNR REMOTE(1) This can be expressed by the following formula (2). The 1 / GSNR in formula (1) above. REMOTE(2) This can be expressed by the following formula (3).

number

Number

[0094] Furthermore, 1 / SNR in the above-described mathematical formula (2) ASE(1) can be expressed by the following mathematical formula (4). 1 / SNR in the above-described mathematical formula (2) NLI(1) can be expressed by the following mathematical formula (5). Note that the first calculation unit 122 can obtain the amplifier noise coefficient NF Amp of the receiving amplifier 10C and the non-linear noise coefficient η of the transmission line 50 from the optical path setting DB111. P AmpIn represents the amplifier input power of the receiving amplifier 10C. h represents Planck's constant. γ represents the signal frequency of the signal light. Δf represents the frequency bandwidth. The same applies to h, γ, and Δf in the mathematical formulas described later. P 2 in represents the transmitter output power.

[0095]

Number

Number

[0096] On the other hand, 1 / SNR in the above-described mathematical formula (3) ASE(2) can be expressed by the following mathematical formula (6). 1 / SNR in the above-described mathematical formula (3) NLI(2) can be expressed by the following mathematical formula (7). Note that the first calculation unit 122 can obtain the amplifier noise coefficient NF Amp of the transmitting amplifier 30C and the non-linear noise coefficient η of the transmission line 53 from the optical path setting DB111. P AmpIn represents the amplifier input power of the transmitting amplifier 30C. P 2 in represents the amplifier output power of the transmitting amplifier 30C.

[0097]

Number

number

[0098] In this way, the amount of noise / signal generated in the remote section Remote By calculating this, the first calculation unit 122 can calculate a specific transmission performance that represents the transmission performance of the optical path including the remote section.

[0099] The second acquisition unit 123 acquires power information for the WDM transmission section from the control unit 15K of ROADM device R1, the control unit 25R of ROADM device R2, and the control unit 35R of ROADM device R3. For example, the second acquisition unit 123 acquires the amplifier input power and amplifier output power of the WDM amplifier 15F from the control unit 15K as power information for the WDM transmission section. The second acquisition unit 123 also acquires the amplifier input power and amplifier output power of the WDM amplifiers 25K and 25L from the control unit 25R as power information for the WDM transmission section. Furthermore, the second acquisition unit 123 acquires the amplifier input power and amplifier output power of the WDM amplifier 35L from the control unit 35R as power information for the WDM transmission section.

[0100] The second calculation unit 124 calculates the amount of noise generated in the WDM transmission section based on the power information of the WDM transmission section. More specifically, the second calculation unit 124 calculates the noise level (Noise / Signal) of the optical path including the WDM transmission section based on the power information of the WDM transmission section and, for example, the following formula (8). WDM Calculate.

number

[0101] Here, in the above formula (8), 1 / GSNR WDM(i) This can be expressed by the following formula (9). Note that WDM(i) represents the noise level of the i-th (i is a natural number) WDM transmission section. For example, the first WDM transmission section corresponds to the transmission section of transmission path 51.

number

[0102] Furthermore, the 1 / SNR in the above formula (9) ASE(i-1) This can be expressed by the following equation (10). ASE(i-1) represents the naturally emitted amplified light of a WDM amplifier that transmits WDM light to the transmission path corresponding to the i-th WDM transmission section. 1 / SNR in the above-mentioned equation (9) ASE(i-2) This can be expressed by the following equation (11). ASE(i-2) represents the naturally emitted amplified light of a WDM amplifier that receives WDM light from the transmission path corresponding to the i-th WDM transmission section. The 1 / SNR in equation (9) above. NLI(i) This can be expressed by the following formula (12). NLI(i) represents the nonlinear interference in the transmission path corresponding to the i-th WDM transmission section. The second calculation unit 124 is the amplifier noise coefficient NF of WDM amplifiers 15F, 25K, etc. Amp The nonlinear noise coefficient η of the transmission line 50 can be obtained from the optical path setting DB111.

[0103]

number

number

number

[0104] Thus, the amount of noise / signal generated in the WDM transmission section WDM By calculating this, the second calculation unit 124 can calculate a specific transmission performance that represents the transmission performance of the optical path including the WDM transmission section.

[0105] The increase amount calculation unit 125 calculates the increase in optical power of the WDM optical Lw in the WDM transmission section. The increase amount calculation unit 125 calculates, for example, the two noise levels (Noise / Signal) mentioned above. Remote Noise / Signal WDMBased on the following formula (13), the optical power increase ΔPowertarget is calculated. The increase amount calculation unit 125 is the basic control target value Powertarget for optical power. Base This can be obtained from the optical path setting DB111.

number

[0106] The setting value calculation unit 126 calculates the signal slot width setting values ​​to be set in ROADM devices R1, R2, ..., R3. That is, the setting value calculation unit 126 calculates the signal slot width setting values ​​to be set in WSS15E, 25I, 25J, 35J, etc. The signal slot width setting value SlotWidth calculated by the setting value calculation unit 126 can be expressed by the following formula (14).

number

[0107] Here, the signal slot width difference ΔSlotWidth in equation (14) can be expressed by the following equation (15). Therefore, equation (14) can be expressed by the following equation (16).

number

number

[0108] As a result, the setting value calculation unit 126 calculates the basic slot width SlotWidth Base The above-mentioned increase in optical power ΔPowertarget and the control target value Powertarget Base Based on formula (16), the signal slot width setting value SlotWidth can be calculated. The setting value calculation unit 126 calculates the slot width SlotWidth Base and control target value Powertarget BaseThis can be obtained from the optical path setting DB111.

[0109] The setting change unit 127 sets the signal slot width setting value SlotWidth calculated by the setting value calculation unit 126 to ROADM devices R1, R2, R3, etc., and changes the settings of ROADM devices R1, R2, R3, etc. More specifically, the setting value calculation unit 126 sets the signal slot width setting value SlotWidth to WSS15E, 25I, 25J, 35J, etc., and changes the settings of WSS15E, 25I, 25J, 35J, etc.

[0110] As a result, the available power changes before and after the setting change, as shown in Figures 8(a) and (b). Channel Ch1 represents the frequency band (or wavelength band) of the remote signal light L1 assigned to optical path 1, which is connected to the optical network NW, for example. Channel Ch2 represents the frequency band (or wavelength band) of the local signal light L5 assigned to optical path 2, which is connected to the optical network NW, for example.

[0111] Here, the optical power increase ΔPowertarget is calculated before the signal slot width setting value SlotWidth is calculated. That is, as shown in Figures 8(a) and (b), the optical power increase ΔPowertarget is determined before the signal slot width setting value SlotWidth. After the optical power increase value ΔPowertarget is determined, the signal slot width setting value SlotWidth, which is achieved by controlling the attenuation amount such as WSS15E, is determined. As a result, while the signal spectral widths Δs1 and Δs2 are maintained, the signal slot width Δf2 in channel Ch1 expands to the signal slot width Δf1 before and after the setting change.

[0112] Here, WSS15E, 25I, 25J, and 35J all control the optical power per unit frequency Δf0 to a constant level, minimizing nonlinear effects (specifically noise) regardless of the symbol rate. Therefore, the assignable power is calculated by multiplying the optical power per unit frequency Δf0 by the number of units of frequency Δf0, N. That is, both signal slot widths Δf1 and Δf2 are calculated by the unit frequency Δf0 × N. In this way, the signal slot width Δf2 is expanded to the signal slot width Δf1, increasing the assignable power and thereby increasing the optical power of the WDM optical light Lw, which includes the remote signal light L1. This suppresses the degradation of transmission performance and enables the extension of the transmission distance.

[0113] Refer to Figure 9 to explain the operation of the NMS100.

[0114] First, the increase amount calculation unit 125 determines whether or not the optical path connected to the optical network NW includes a remote section (step S1). The increase amount calculation unit 125 can determine whether or not a remote section is included by obtaining remote identification information from the optical path setting DB 111.

[0115] If the optical path includes a remote section (step S1: YES), the first acquisition unit 121 acquires power information for the remote section (step S2). Once the first acquisition unit 121 acquires power information for the remote section, the first calculation unit 122 calculates the noise level for the remote section (step S3). As described above, the first calculation unit 122 can calculate the noise level generated in the remote section based on the power information for the remote section.

[0116] When the first calculation unit 122 calculates the noise level in the remote section, the second acquisition unit 123 acquires power information for the WDM transmission section (step S4). When the second acquisition unit 123 acquires power information for the WDM transmission section, the second calculation unit 124 calculates the noise level in the WDM transmission section (step S5). As described above, the second calculation unit 124 can calculate the noise level generated in the WDM transmission section based on the power information for the WDM transmission section.

[0117] When the second calculation unit 124 calculates the noise level of the WDM transmission section, the increase amount calculation unit 125 calculates the optical power increase (step S6). The increase amount calculation unit 125 can calculate the optical power increase based on the two noise levels calculated in steps S3 and S5. When the increase amount calculation unit 125 calculates the optical power increase, the setting value calculation unit 126 calculates the slot width setting value (step S7). The setting value calculation unit 126 can calculate the slot width setting value based on the optical power increase calculated in step S6.

[0118] When the setting value calculation unit 126 calculates the slot width setting value, the setting change unit 127 sets the slot width (step S8). That is, the setting change unit 127 changes the settings of ROADM devices R1, R2, R3, etc., based on the slot width setting value calculated by the setting value calculation unit 126. Once the setting change unit 127 sets the slot width, the NMS 100 terminates processing.

[0119] In step S1, if the optical path does not include a remote section (step S1: NO), the setting value calculation unit 126 sets the slot width expansion amount to zero (step S9). When the setting value calculation unit 126 sets the slot width expansion amount to zero, the setting change unit 127 executes the process in step S8. As a result, if the optical path does not include a remote section, the slot width before the setting change is maintained. When the setting change unit 127 executes the process in step S8, the NMS 100 terminates processing.

[0120] Referring to Figures 10 and 11, the effects of this case will be explained in comparison with the comparative example.

[0121] First, in the comparative example, as shown in Figure 10, in the case of optical path 1 which includes a remote section, the cumulative noise amount increases by the amount of the remote section compared to optical path 2 which does not include a remote section. Thus, the cumulative noise amount differs depending on whether or not there is a remote section. An increase in cumulative noise leads to a decrease in transmission performance. Therefore, the transmission performance of optical path 1 is worse than that of optical path 2. Consequently, when there is a remote section, it becomes difficult to extend the transmission distance.

[0122] On the other hand, in the embodiment, as shown in Figure 11, in the case of optical path 1 which includes a remote section, the cumulative noise increases by the amount of the remote section compared to optical path 2 which does not include a remote section. However, in the WDM transmission section, the rate of increase in cumulative noise is mitigated by changing the settings of ROADM devices R1, R2, R3, etc. As a result, the cumulative noise of optical path 1 is reduced in ROADM device R3 to an equivalent degree to the cumulative noise of optical path 2. Consequently, optical path 1 and optical path 2 can achieve similar transmission performance. Therefore, even when there is a remote section, it becomes possible to extend the transmission distance.

[0123] Furthermore, as shown in Figure 12, in another embodiment, even when the remote section is on the receiving side, the cumulative noise is reduced in the same way as when the remote section is on the transmitting side, as explained with reference to Figure 11. Therefore, even when the remote section is on the receiving side, the transmission distance can be extended in the same way as when the remote section is on the transmitting side.

[0124] Referring to Figures 13 to 15, the effects of this case based on differences in transmission models will be explained in comparison with several comparative examples.

[0125] First, as shown in Figure 13, the first transmission model #1 uses a data rate of 800 Gbps. The first transmission model #1 corresponds to the case described with reference to Figures 10 and 11. In comparative examples 1 to 3, which correspond to Figure 10, and the embodiment, which corresponds to Figure 11, a starting section length of 60 km is used, representing the section length of the remote section (transmitter side).

[0126] As shown in Figure 13, in Comparative Examples 1 and 2, the cumulative GOSNR (Generalized Optical Signal to Noise Ratio) is relatively small compared to Comparative Example 3 and the Example. Therefore, a negative value is recorded as the transmission margin, making transmission difficult. On the other hand, in Comparative Example 3 and the Example, the cumulative GOSNR is relatively large compared to Comparative Examples 1 and 2. Therefore, a positive value is recorded as the transmission margin, ensuring the realization of transmission. In particular, in the Example, compared to Comparative Example 3, an effect of extending the transmission distance in the WDM transmission section (indicated as the WDM section in Figures 13 to 15) can be observed.

[0127] Next, as shown in Figure 14, in the second transmission model #2, a data rate of 1 Tbps is adopted. The embodiment in the second transmission model #2 corresponds to the case described with reference to Figure 12. Comparative Examples 1 and 2 in the second transmission model #2, although not shown, correspond to the configuration in Figure 12 without any setting changes. In Comparative Examples 1 and 2 and the embodiment, a starting section length of 50 km is adopted, representing the section length of the remote section (transmitter side).

[0128] As shown in Figure 14, in Comparative Example 1, the cumulative GOSNR is relatively small compared to Comparative Example 2 and the Example. Therefore, a negative value is recorded as the transmission margin, making transmission difficult to achieve. On the other hand, in Comparative Example 2 and the Example, the cumulative GOSNR is relatively large compared to Comparative Example 1. Therefore, a positive value is recorded as the transmission margin, ensuring the realization of transmission. In particular, in the Example, an effect of extending the transmission distance in the WDM transmission section is observed compared to Comparative Example 2.

[0129] Next, as shown in Figure 15, in the third transmission model #3, a data rate of 800 Gbps is adopted. The embodiment in the third transmission model #3 corresponds to the case where the settings are changed in the configuration of Figure 1. Comparative examples 1 to 3 in the third transmission model #3 correspond to the case where the settings are not changed in the configuration of Figure 1. In comparative examples 1 to 3 and the embodiment, 50 km is adopted as the start section length representing the section length of the remote section (transmitter side). Also, in comparative examples 1 to 3 and the embodiment, 50 km is adopted as the goal section length representing the section length of the remote section (receiver side).

[0130] As shown in Figure 15, in Comparative Examples 1 and 2, the cumulative GOSNR is relatively small compared to Comparative Example 3 and the Example. Therefore, a negative value is recorded as the transmission margin, making transmission difficult to achieve. On the other hand, in Comparative Example 3 and the Example, the cumulative GOSNR is relatively large compared to Comparative Examples 1 and 2. Therefore, a positive value is recorded as the transmission margin, ensuring the realization of transmission. In particular, in the Example, an effect of extending the transmission distance in the WDM transmission section is observed compared to Comparative Example 3.

[0131] (Second Embodiment) A second embodiment of this invention will be described with reference to Figure 16. In the first embodiment, a setting change to increase the slot width was described as an example, but depending on the accommodation conditions of optical paths 1 and 2 etc. that are accommodated in the optical network NW, the amount of slot width increase may be limited. If the amount of increase is limited, it may not be possible to sufficiently reduce the amount of noise.

[0132] In such cases, the NMS 100 may increase the symbol rate of the optical transmitter 5A, for example, in addition to increasing the slot width. For example, the NMS 100 notifies the control unit 10E of the photonic gateway P1 of a transmission request for OSC optical Lo1, which includes an instruction to increase the symbol rate of the optical transmitter 5A. Based on the transmission request, the control unit 10E controls the OSC communication unit 10A. As a result, the OSC communication unit 10A transmits OSC optical Lo1, which includes an instruction to increase the symbol rate of the optical transmitter 5A.

[0133] The OSC communication unit 5E of the remote transponder RS ​​can receive OSC optical Lo1. Therefore, when the OSC communication unit 5E receives OSC optical Lo1, it notifies the control unit 5F to increase the symbol rate of the optical transmitter 5A. This allows the control unit 5F to increase the symbol rate of the optical transmitter 5A. In this way, even if the amount of noise cannot be sufficiently reduced due to the limitation of the slot width expansion, increasing the symbol rate reduces the cumulative noise of optical path 1 in an equivalent manner to the cumulative noise of optical path 2, as shown in Figure 16.

[0134] (Third embodiment) Referring to Figure 17, a third embodiment of this invention will be described. As explained in the second embodiment, the amount of expansion of the slot width may be limited depending on the accommodation status of optical paths 1, 2, etc., that are accommodated in the optical network NW.

[0135] In such cases, the NMS100 may, in addition to expanding the slot width, assign ROADM devices R1, R2, R3, etc., to channels with low noise in the WDM transmission section. Even if the noise level cannot be sufficiently reduced due to the limitation on the amount of slot width expansion, by assigning to channels with low noise, the cumulative noise level of optical path 1 is reduced in an equivalent manner to the cumulative noise level of optical path 2, as shown in Figure 17.

[0136] (Fourth Embodiment) Referring to Figure 18, a fourth embodiment of this invention will be described. As explained in the second embodiment, the amount of expansion of the slot width may be limited depending on the accommodation status of optical paths 1, 2, etc., that are accommodated in the optical network NW.

[0137] In such cases, NMS100 may, in conjunction with expanding the slot width, request ROADM devices R1, R2, and R3 to reduce the attenuation of WSS15E, 25I, 25J, and 35J in the WDM transmission section. When the attenuation of WSS15E, 25I, 25J, and 35J is reduced, the optical power of the channels to be attenuated increases compared to the optical power before attenuation, and the noise level decreases. On the other hand, ALC reduces the optical power of channels not to be attenuated compared to the optical power before attenuation, and the noise level increases. As a result, as shown in Figure 18, the cumulative noise level of optical path 1 corresponding to the channels to be attenuated is reduced in an equivalent manner to the cumulative noise level of optical path 2 corresponding to the channels not to be attenuated.

[0138] Although preferred embodiments of the present invention have been described in detail above, the present invention is not limited to specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention as described in the claims. For example, although the first calculation unit 122 and the second calculation unit 124 described above each calculate the noise amount, instead of the noise amount, the amount of degradation in signal quality such as the remote signal light L1 in the remote section may be calculated. The signal quality may be any of SNR, GSNR, OSNR, or GOSNR. Furthermore, although in the above-described embodiment the NMS 100 controls the operation of ROADM devices R1, R2, ..., R3 and the remote transponder RS, the NMS 100 may also control the operation of photonic gateways P1 and P3. In this case, WSS may be provided before or after the receiving amplifier 10C and the transmitting amplifier 30C.

[0139] Furthermore, the following additional information is disclosed regarding the above explanation. (Note 1) A network control device for controlling a plurality of devices included in an optical network, comprising: an acquisition unit that acquires first information indicating the transmission status of at least one of an optical transceiver; a first WDM device connected to the optical transceiver across a first transmission path; and a second WDM device connected to the first WDM device across a second transmission path separate from the first transmission path; a calculation unit that calculates the transmission performance in the first transmission path based on the first information; and a setting change unit that changes the setting of at least one of the optical transceiver, the first WDM device, and the second WDM device based on the transmission performance in the first transmission path. (Note 2) The network control device according to Note 1, wherein the optical transceiver includes an optical transmitter that transmits signal light, the first WDM device includes a first amplifier that receives and amplifies the signal light from the optical transceiver, the acquisition unit acquires the output power of the optical transceiver and the input power of the signal light to the first amplifier as first information, the calculation unit calculates the specific transmission performance based on the first information, and the setting change unit changes the settings of at least one of the optical transceiver and the first WDM device based on the transmission performance in the first transmission path. (Note 3) The network control device according to Note 1, characterized in that the first WDM device includes a second amplifier that amplifies and transmits signal light, the optical transceiver includes an optical receiver that receives the signal light from the first WDM device, the acquisition unit acquires the input power of the signal light to the second amplifier and the output power of the signal light from the second amplifier as first information, the calculation unit calculates the transmission performance in the first transmission path based on the first information, and the setting change unit changes the settings of at least one of the first WDM device and the second WDM device based on the transmission performance in the first transmission path. (Note 4) The network control device according to any one of Notes 1 to 3, characterized in that the setting change unit changes the setting of the second WDM device for the signal light of the channel relating to the transmission performance in the first transmission path to a setting that increases the output power of the second WDM device, based on the transmission performance in the first transmission path. (Note 5) The network control device according to any one of Notes 1 to 3, wherein the second WDM device includes a WSS that outputs signal light to a downstream optical amplifier, and the setting change unit changes the setting of the WSS for the signal light of the channels relating to the transmission performance in the first transmission path to a setting that increases the output power of the WSS, and limits the maximum number of channels of the signal light output from the WSS to the optical amplifier. (Note 6) The network control device according to any one of Notes 1 to 3, wherein the second WDM device includes a WSS that controls the output power per unit frequency to be constant regardless of the symbol rate of the optical transmitter provided in the optical transceiver and outputs signal light to a downstream optical amplifier, and the setting change unit changes the slot width of the WSS for the signal light of the channel relating to the transmission performance in the first transmission path to a slot width that increases the output power of the second WDM device, based on the transmission performance in the first transmission path. (Note 7) The network control device according to any one of Notes 1 to 3, characterized in that the setting change unit changes the symbol rate of the optical transmitter provided in the optical transceiver based on the transmission performance in the first transmission line. (Note 8) The network control device according to any one of Notes 1 to 3, characterized in that the calculation unit calculates the amount of decrease in OSNR of the signal light in the first transmission path. (Note 9) The network control device according to any one of Notes 1 to 3, characterized in that the first WDM device includes different first optical devices and second optical devices connected to each other by a first optical fiber, both the first transmission line and the second transmission line include a second optical fiber of a different type from the first optical fiber, the optical transceiver is connected to the first optical device across the first transmission line, and the second WDM device is connected to the second optical device across the second transmission line. (Note 10) The network control device according to any one of Notes 1 to 3, characterized in that when the acquisition unit acquires the first information from the optical transceiver, it acquires the first information using OSC light, and when acquiring the first information from the first WDM device and the second WDM device, it acquires the first information using electrical signals without using OSC light. (Note 11) An optical network system comprising: an optical transceiver; a first WDM device connected to the optical transceiver across a first transmission path; a second WDM device connected to the first WDM device across a second transmission path separate from the first transmission path; and a network control device that acquires first information indicating the transmission status of each from at least one of the optical transceiver, the first WDM device, and the second WDM device, calculates the transmission performance in the first transmission path based on the first information, and changes the settings of at least one of the optical transceiver, the first WDM device, and the second WDM device based on the transmission performance in the first transmission path. [Explanation of Symbols]

[0140] NW Optical Network RS, RG Remote Transponder P1, P3 Photonic Gateway R1,R2,R3 ROADM device 100 NMS 121 First acquisition part 122 First Calculation Unit 123 Second Acquisition Department 124 Second Calculation Unit 125 Increase Calculation Unit 126 Setting Value Calculation Unit 127 Settings Change Section

Claims

1. A network control device that controls multiple devices included in an optical network, An acquisition unit that acquires first information indicating the transmission status of at least one of the following: an optical transceiver; a first WDM (Wavelength Division Multiplexing) device connected to the optical transceiver across a first transmission path; and a second WDM device connected to the first WDM device across a second transmission path separate from the first transmission path. A calculation unit that calculates the transmission performance in the first transmission line based on the first information, A setting change unit that changes the setting of at least one of the optical transceiver, the first WDM device, and the second WDM device based on the transmission performance in the first transmission line, A network control device.

2. The optical transceiver includes an optical transmitter that transmits signal light, The first WDM device includes a first amplifier that receives and amplifies the signal light from the optical transceiver, The acquisition unit acquires the output power of the optical transceiver and the input power of the signal light to the first amplifier as first information. The calculation unit calculates the transmission performance in the first transmission line based on the first information, The setting change unit changes the settings of at least one of the optical transceiver and the first WDM device based on the transmission performance in the first transmission path. The network control device according to feature 1.

3. The first WDM device includes a second amplifier that amplifies and transmits the signal light. The optical transceiver includes an optical receiver that receives the signal light from the first WDM device. The acquisition unit acquires the input power of the signal light to the second amplifier and the output power of the signal light from the second amplifier as first information. The calculation unit calculates the transmission performance in the first transmission line based on the first information, The setting change unit changes the settings of at least one of the first WDM device and the second WDM device based on the transmission performance in the first transmission line. The network control device according to feature 1.

4. The setting change unit changes the setting of the second WDM device for the signal light of the channel related to the transmission performance in the first transmission path, based on the transmission performance in the first transmission path, to a setting that increases the output power of the second WDM device. A network control device according to any one of claims 1 to 3.

5. The second WDM device includes a WSS (Wavelength Selective Switch) that outputs signal light to a downstream optical amplifier. The setting change unit changes the setting of the WSS for the signal light of the channel relating to the transmission performance in the first transmission path to a setting that increases the output power of the WSS, and limits the maximum number of channels of the signal light output from the WSS to the optical amplifier. A network control device according to any one of claims 1 to 3.

6. The second WDM device includes a Wavelength Selective Switch (WSS) that controls the output power per unit frequency to be constant regardless of the symbol rate of the optical transmitter provided in the optical transceiver, and outputs the signal light to a downstream optical amplifier. The setting change unit changes the slot width of the WSS for the signal light of the channel related to the transmission performance in the first transmission line to a slot width that increases the output power of the second WDM device, based on the transmission performance in the first transmission line. A network control device according to any one of claims 1 to 3.

7. The setting change unit changes the symbol rate of the optical transmitter provided in the optical transceiver based on the transmission performance in the first transmission line. A network control device according to any one of claims 1 to 3.

8. The calculation unit calculates the amount of decrease in the OSNR (Optical Signal to Noise Ratio) of the signal light in the first transmission line. A network control device according to any one of claims 1 to 3.

9. Optical transceiver and, The optical transceiver and the first WDM (Wavelength Division Multiplexing) device connected across the first transmission line, A second WDM device is connected to the first WDM device via a second transmission line, which is separate from the first transmission line. A network control device that acquires first information indicating the transmission status of at least one of the optical transceiver, the first WDM device, and the second WDM device, calculates the transmission performance in the first transmission path based on the first information, and changes the settings of at least one of the optical transceiver, the first WDM device, and the second WDM device based on the transmission performance in the first transmission path, An optical network system having

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