Local node, leaf node and optical communication network

Abstract

This application provides a central office node, a leaf node, and an optical communication network, belonging to the field of optical communication technology. The central office node includes a multiplexing module, a wavelength division multiplexing module, a light source module, and a transceiver module. Both the multiplexing and wavelength division multiplexing modules are used to connect to the outer and inner ring optical fibers. The light source module provides the transceiver module with local oscillator light and signal light of the same wavelength. The local oscillator light includes at least one of a first wavelength and a second wavelength. The transceiver module uses the local oscillator light to receive uplink signals transmitted by the multiplexing module. These uplink signals include at least one of a first wavelength and a second wavelength. The transceiver module can also generate downlink signals based on the signal light and transmit these downlink signals to the wavelength division multiplexing module. These downlink signals include at least one of a first wavelength and a second wavelength. This allows data transmission using both first and second wavelengths, simplifying the data transmission process.

Description

Technical Field

[0001] This application relates to the field of optical communication technology, and in particular to a central office node, a leaf node, and an optical communication network. Background Technology

[0002] Metropolitan Area Networks (MANs) are located at the intersection of backbone and access networks, making them one of the most complex network environments in communications. Various types of service data with different requirements are carried directly or indirectly through the MAN, undergoing aggregation, distribution, and transmission to and from the backbone network within its scope. Typically, MANs employ a dual-fiber ring network architecture, consisting of a central office node and multiple leaf nodes. Starting from and ending at the central office node, the leaf nodes are connected in series via two optical fibers to form a ring structure. Both the outer and inner ring fibers in the dual-fiber configuration are used for communication between the central office node and the multiple leaf nodes.

[0003] When the central node communicates with multiple leaf nodes, the central node and leaf nodes communicate based on dense wavelength division multiplexing (DWDM) technology, which makes the data transmission process relatively complex. Summary of the Invention

[0004] This application provides a central office node, leaf node, and optical communication network that can use at least one of a first wavelength of light and a second wavelength of light to achieve data transmission, simplifying the data transmission process.

[0005] In a first aspect, this application provides a central office node, comprising a multiplexing module, a wavelength division multiplexing module, a light source module, and a transceiver module. Both the multiplexing module and the wavelength division multiplexing module are used to connect to an outer ring optical fiber and an inner ring optical fiber. The multiplexing module is used to receive uplink signals and transmit the uplink signals to the transceiver module. The light source module is used to provide the transceiver module with local oscillator light and signal light of the same wavelength, the local oscillator light comprising at least one of a first wavelength and a second wavelength. The transceiver module is used to receive the uplink signal transmitted by the multiplexing module based on the local oscillator light, generate a downlink signal based on the signal light, and transmit the downlink signal to the wavelength division multiplexing module. The uplink signal comprises at least one of the first wavelength and the second wavelength, and the downlink signal comprises at least one of the first wavelength and the second wavelength. The wavelength division multiplexing module is used to transmit the downlink signal received from the transceiver module.

[0006] The scheme shown in this application allows the central node to communicate with all leaf nodes using at least one of a first wavelength and a second wavelength, instead of using DWDM technology. This requires fewer lasers than the number of leaf nodes and simplifies the data transmission process.

[0007] In one possible implementation, assuming the optical communication network to which the central office node belongs is functioning correctly, the multiplexing module receives the uplink signal of the first wavelength from the outer ring fiber and transmits the uplink signal of the first wavelength to the transceiver module; the wavelength division module outputs the downlink signal of the first wavelength to the inner ring fiber. Alternatively, the multiplexing module receives the uplink signal of the second wavelength from the inner ring fiber and transmits the uplink signal of the second wavelength to the transceiver module; the wavelength division module outputs the downlink signal of the second wavelength to the outer ring fiber.

[0008] The solution presented in this application, when the optical communication network to which the central office node belongs is not faulty, includes both local oscillator light and signal light, which are either light of a first wavelength or light of a second wavelength. The central office node can flexibly choose to use either light of the first wavelength or light of the second wavelength for communication.

[0009] In one possible implementation, assuming the optical communication network to which the central office node belongs is functioning correctly, the multiplexing module is configured to receive the uplink signal of the first wavelength from the outer ring optical fiber and transmit the uplink signal of the first wavelength to the transceiver module, or receive the uplink signal of the second wavelength from the inner ring optical fiber and transmit the uplink signal of the second wavelength to the transceiver module. The wavelength division module is configured to divide the downlink signal received from the transceiver module into a downlink signal of the first wavelength and a downlink signal of the second wavelength, output the downlink signal of the first wavelength to the inner ring optical fiber, and output the downlink signal of the second wavelength to the outer ring optical fiber.

[0010] The scheme presented in this application, assuming the optical communication network to which the central office node belongs is functioning correctly, includes both a first wavelength and a second wavelength in both the local oscillator light and the signal light. The central office node only receives either the first wavelength uplink signal or the second wavelength uplink signal, without repeatedly receiving uplink signals. Furthermore, the central office node can output both the first wavelength downlink signal and the second wavelength downlink signal, thus enabling downlink communication.

[0011] In one possible implementation, in the event of a failure in the optical communication network to which the central office node belongs, the local oscillator light comprises light of the first wavelength and light of the second wavelength. The multiplexing module receives the uplink signal of the first wavelength from the outer ring fiber and the uplink signal of the second wavelength from the inner ring fiber, combines the uplink signal of the first wavelength and the uplink signal of the second wavelength into a single uplink signal, and transmits this single uplink signal to the transceiver module. The wavelength division module divides the downlink signal received from the transceiver module into a downlink signal of the first wavelength and a downlink signal of the second wavelength, outputs the downlink signal of the first wavelength to the inner ring fiber, and outputs the downlink signal of the second wavelength to the outer ring fiber.

[0012] The scheme presented in this application, when the optical communication network to which the central office node belongs is not faulty, includes both local oscillator light and signal light comprising a first wavelength and a second wavelength. The central office node can receive uplink signals of the first and second wavelengths respectively through the outer and inner ring optical fibers, and can also broadcast downlink signals of the second and first wavelengths respectively through the outer and inner ring optical fibers. This allows leaf nodes on both sides of the fault point to communicate with the central office node using the first and second wavelengths of light respectively, thus ensuring that the transmission of service data is not affected when the optical communication network fails.

[0013] In one possible implementation, the transceiver module includes a receiving unit and a transmitting unit. The light source module is used to provide the local oscillator light to the receiving unit and the signal light to the transmitting unit. The receiving unit is used to receive the uplink signal sent by the multiplexing module based on the local oscillator light, and the transmitting unit is used to send the downlink signal to the demultiplexing module based on the signal light.

[0014] In one possible implementation, the local oscillator light includes light of the first wavelength and light of the second wavelength, and the light source module includes a first laser, a second laser, and a multiplexing / demultiplexing unit. The first laser and the second laser are respectively connected to the multiplexing / demultiplexing unit. The first laser is used to output light of the first wavelength, and the second laser is used to output light of the second wavelength. The multiplexing / demultiplexing unit is used to combine the first wavelength light and the second wavelength light into one beam, and split the one beam into two beams, which are then transmitted to the receiving unit and the transmitting unit, respectively. Thus, since the local oscillator light and signal light provided by the light source module both include light of the first wavelength and light of the second wavelength, regardless of whether the optical communication network is faulty, there is no need for switching based on whether the optical communication network is faulty, simplifying the control logic.

[0015] In one possible implementation, the transceiver module further includes a processing unit. This processing unit controls the light source module to transmit both the first wavelength and the second wavelength light to both the receiving unit and the transmitting unit when the optical communication network to which the central office node belongs is faulty; conversely, when the optical communication network to which the central office node belongs is not faulty, it transmits either the first wavelength light or the second wavelength light to both the receiving unit and the transmitting unit. Thus, regardless of whether the optical communication network is faulty or not, the processing unit controls the local oscillator light and signal light provided by the light source module, eliminating the need for the light source module to continuously provide the first and second wavelength light, thereby reducing the power consumption of the light source module.

[0016] In one possible implementation, the central office node further includes a first optical switch and a second optical switch. The first optical switch is disposed between the first input port of the multiplexing module and the outer ring fiber, and the second optical switch is disposed between the first output port of the wavelength division multiplexing module and the inner ring fiber. The first input port and the first output port are used to transmit a signal of the first wavelength. Alternatively, the first optical switch is disposed between the second input port of the multiplexing module and the inner ring fiber, and the second optical switch is disposed between the second output port of the wavelength division multiplexing module and the outer ring fiber. The second input port and the second output port are used to transmit a signal of the second wavelength. The first and second optical switches are in a closed state in the event of a fault in the optical communication network to which the central office node belongs, and in an open state when the optical communication network to which the central office node belongs is not faulty.

[0017] The solution presented in this application, when both the local oscillator light and the signal light include light of a first wavelength and light of a second wavelength, includes a first optical switch and a second optical switch at the central office node. When the optical communication network is functioning correctly, only the downlink signal of the first wavelength or the downlink signal of the second wavelength can be output from the central office node, and only the uplink signal of the first wavelength or the uplink signal of the second wavelength can be input to the transceiver module for reception by the central office node. Furthermore, in the event of a failure in the optical communication network, both the downlink signal of the first wavelength and the downlink signal of the second wavelength can be output from the central office node, and both the uplink signal of the first wavelength and the uplink signal of the second wavelength can be input to the transceiver module for reception by the central office node.

[0018] In one possible implementation, both the uplink and downlink signals of the first wavelength include subcarrier signals, and both the uplink and downlink signals of the second wavelength include subcarrier signals. This allows leaf nodes to be distinguished based on subcarriers, reducing the number of wavelengths of light provided by the light source module.

[0019] In one possible implementation, the transceiver module is further configured to determine whether the optical communication network to which the central office node belongs is faulty based on whether the received multi-subcarrier signal carries a fault indication message; or, based on the number of subcarriers in the received multi-subcarrier signal, determine whether the optical communication network to which the central office node belongs is faulty.

[0020] The scheme presented in this application allows the transceiver module to determine if the optical communication network is faulty by obtaining a fault indication message from the multi-subcarrier signal; otherwise, it determines that the optical communication network is not faulty. Alternatively, if the number of subcarriers in the multi-subcarrier signal received by the transceiver module is less than the number of leaf nodes, it determines that some leaf nodes have not transmitted subcarrier signals, thus determining that the optical communication network is faulty; otherwise, it determines that the optical communication network is not faulty. This allows for flexible determination of whether the optical communication network is faulty.

[0021] Secondly, this application provides a leaf node, which includes a light source module, a first uplink / downlink module, a transceiver module, and a second uplink / downlink module. The light source module provides the transceiver module with local oscillator light and signal light of the same wavelength, the local oscillator light including at least a third wavelength. The first uplink / downlink module receives a first downlink signal from a first optical fiber, splits the first downlink signal into two downlink signals, and transmits them to the transceiver module and the first optical fiber, respectively. The transceiver module, based on the local oscillator light, extracts the third wavelength downlink signal from the received downlink signal, and generates at least the third wavelength uplink signal based on the signal light, transmitting the generated signal to the second uplink / downlink module. The second uplink / downlink module combines the uplink signal received from the second optical fiber with the third wavelength uplink signal and outputs it to the second optical fiber.

[0022] The scheme shown in this application provides a local oscillator light and signal light from a light source module, both of which include at least a third wavelength. Leaf nodes can use this third wavelength light to communicate with the central office node. Furthermore, leaf nodes continue to transmit the downlink signals transmitted by the central office node, enabling other leaf nodes to communicate with the central office node. Additionally, leaf nodes transmit uplink signals sent by other leaf nodes to the central office node back to the central office node. Therefore, even when the central office node does not employ DWDM technology, leaf nodes can still communicate with it using a third wavelength light, simplifying the data transmission process.

[0023] In one possible implementation, in the event of a target communication link interruption at the leaf node, the local oscillator light includes at least a fourth wavelength of light, and the leaf node further includes a first routing module and a second routing module. The second uplink / downlink module is used to receive a second downlink signal from the second optical fiber, split the second downlink signal into two downlink signals, and transmit them to the first routing module and the second optical fiber, respectively. The first routing module is used to transmit the downlink signal received from the second uplink / downlink module to the transceiver module. The transceiver module is used to, based on the local oscillator light, extract the fourth wavelength downlink signal from the received downlink signal, and generate at least the fourth wavelength uplink signal based on the signal light, and transmit the generated signal to the second routing module. The second routing module is used to transmit the fourth wavelength uplink signal from the received signal to the first uplink / downlink module. The first uplink / downlink module is used to combine the uplink signal received from the first optical fiber with the fourth wavelength uplink signal and output it to the first optical fiber.

[0024] The scheme shown in this application has a leaf node connected to a first optical fiber and a second optical fiber. The leaf node communicates with the central office node via the first and second optical fibers for uplink and downlink communication, respectively. The leaf node can also communicate with the central office node via the second and first optical fibers for uplink and downlink communication, respectively. In this way, the leaf node can communicate with the central office node through two communication links, and the target communication link of the leaf node is one of the two communication links.

[0025] In the event of a target communication link being interrupted, the leaf node can select another communication link through the first and second routing modules to ensure uninterrupted service transmission.

[0026] In one possible implementation, assuming the target communication link at the leaf node is uninterrupted, the first uplink / downlink module receives a first downlink signal from the first optical fiber, splits the first downlink signal into two downlink signals, and transmits them to the first routing module and the first optical fiber, respectively. The first routing module transmits the downlink signal received from the first uplink / downlink module to the transceiver module. The transceiver module generates an uplink signal of at least the third wavelength based on the signal light and transmits the generated signal to the second routing module. The second routing module transmits the uplink signal of the third wavelength from the received signal to the second uplink / downlink module.

[0027] The scheme shown in this application includes a first routing module and a second routing module in the leaf node. When the target communication link is not interrupted, the leaf node can select the target communication link for communication through the first routing module and the second routing module.

[0028] In one possible implementation, the transceiver module includes a receiving unit and a transmitting unit. The light source module is used to provide the local oscillator light to the receiving unit and the signal light to the transmitting unit. The receiving unit is used to receive uplink signals based on the local oscillator light, and the transmitting unit is used to transmit downlink signals based on the signal light.

[0029] In one possible implementation, the local oscillator light includes light of the third wavelength and light of the fourth wavelength, and the light source module includes a first laser, a second laser, and a multiplexing / demultiplexing unit. The first laser and the second laser are respectively connected to the multiplexing / demultiplexing unit. The first laser is used to output light of the third wavelength, and the second laser is used to output light of the fourth wavelength. The multiplexing / demultiplexing unit is used to combine the third wavelength light and the fourth wavelength light into one beam, and split the one beam into two beams, which are then transmitted to the receiving unit and the transmitting unit, respectively. Thus, since the local oscillator light and signal light provided by the light source module both include light of the first wavelength and light of the second wavelength regardless of whether the target communication link is interrupted, switching based on whether the target communication link is interrupted is not required, simplifying the control logic.

[0030] In one possible implementation, the light source module includes a first laser, a second laser, a switching unit, and a wavelength division unit. The switching unit is connected to the wavelength division unit. The first laser outputs light of a third wavelength, and the second laser outputs light of a fourth wavelength. The switching unit connects to the first laser when the target communication link of the leaf node is uninterrupted, and to the second laser when the target communication link of the leaf node is interrupted. The wavelength division unit splits the received light into two paths, which are then transmitted to the receiving unit and the transmitting unit, respectively. Thus, by selecting light emitted from different lasers depending on whether the target communication link is interrupted or not, the leaf node can communicate using different wavelengths of light in both cases, thereby enabling communication through different communication links.

[0031] In one possible implementation, both the first and second up-and-down wave modules are 2×2 optical couplers. This simplifies the optical coupler structure, resulting in smaller leaf node sizes and lower costs.

[0032] In one possible implementation, the first uplink / downlink module includes a first wavelength division unit, a first 1×2 optical coupler, a first multiplexing unit, and a first 2×1 optical coupler. When the target communication link is uninterrupted, the first wavelength division unit receives the first downlink signal from the first optical fiber and transmits the first downlink signal to the first 1×2 optical coupler; the first 1×2 optical coupler splits the first downlink signal into two downlink signals, which are transmitted to the first multiplexing unit and the first routing module, respectively; the first multiplexing unit outputs the received downlink signal back to the first optical fiber. When the target communication link is interrupted, the first wavelength division unit receives the uplink signal from the first optical fiber and transmits the received uplink signal to the first 2×1 optical coupler; the first 2×1 optical coupler receives the fourth wavelength uplink signal transmitted by the second routing module, combines the two received uplink signals into one uplink signal, and transmits it to the first multiplexing unit; the first multiplexing unit outputs the received uplink signal back to the first optical fiber.

[0033] In the scheme shown in this application, when the target communication link is not interrupted, the downlink signal received by the leaf node enters a 1×2 optical coupler through the first wavelength division unit. This 1×2 optical coupler splits the downlink signal into two downlink signals, which are then output directly and output as downlink signals, respectively. When the target communication link is interrupted, the uplink signal received by the leaf node enters a 2×1 optical coupler through the first wavelength division unit. The 2×1 optical coupler combines the uplink input signal and the uplink signal received by the leaf node into a single uplink signal, which is then output directly. It is evident that when the first uplink / downlink module implements both downlink and uplink functions, the downlink and uplink signals received by the leaf node follow different paths. Therefore, flexibly configuring the power ratio of the downlink signal output directly and the downlink input signal as downlink signal will not affect the uplink signal.

[0034] In one possible implementation, the second uplink / downlink module includes a second wavelength division unit, a second 1×2 optical coupler, a second wavelength multiplexing unit, and a second 2×1 optical coupler. When the target communication link is uninterrupted, the second wavelength division unit receives uplink signals from the second optical fiber and transmits the received uplink signals to the second 2×1 optical coupler; the second 2×1 optical coupler receives the uplink signal of the third wavelength transmitted by the second routing module, combines the two received uplink signals into one uplink signal, and transmits it to the second wavelength multiplexing unit; the second wavelength multiplexing unit outputs the received uplink signal to the first optical fiber. When the target communication link is interrupted, the second wavelength division unit receives the second downlink signal from the second optical fiber and transmits the second downlink signal to the second 1×2 optical coupler; the second 1×2 optical coupler splits the second downlink signal into two downlink signals, which are transmitted to the second wavelength multiplexing unit and the first routing module respectively; the second wavelength multiplexing unit outputs the received downlink signal to the second optical fiber.

[0035] In the scheme shown in this application, when the target communication link is not interrupted, the downlink signal received by the leaf node enters a 1×2 optical coupler through the second wavelength division unit. This 1×2 optical coupler splits the downlink signal into two downlink signals, which are then output directly and output as downlink signals, respectively. When the target communication link is interrupted, the uplink signal received by the leaf node enters a 2×1 optical coupler through the second wavelength division unit. The 2×1 optical coupler combines the uplink input signal and the uplink signal received by the leaf node into a single uplink signal, which is then output directly. Therefore, when the second uplink / downlink module implements both downlink and uplink functions, the downlink and uplink signals received by the leaf node follow different paths. Thus, flexibly configuring the power ratio of the downlink signal output directly and the downlink input signal as downlink signal will not affect the uplink signal.

[0036] In one possible implementation, the first port of the first routing module is used to filter the signal input through the first up-and-down module, and this first port is connected to the first up-and-down module. The second port of the first routing module is used to filter the signal input through the second up-and-down module, and this second port is connected to the second up-and-down module. This prevents the signal input through the leaf node from entering the transceiver module again, thereby preventing the signal emitted by the leaf node from being received by the leaf node itself.

[0037] In one possible implementation, both the uplink and downlink signals of the third wavelength are subcarrier signals, as are the uplink and downlink signals of the fourth wavelength. This allows different leaf nodes to use different subcarriers, enabling each leaf node to accurately receive its own data.

[0038] In one possible implementation, the first optical fiber is an outer ring optical fiber and the second optical fiber is an inner ring optical fiber; or, the first optical fiber is an inner ring optical fiber and the second optical fiber is an outer ring optical fiber.

[0039] Thirdly, this application provides an optical communication network comprising a central office node, multiple leaf nodes, an outer ring optical fiber, and an inner ring optical fiber. The central office node and the multiple leaf nodes are connected in series via the outer ring optical fiber, and the central office node and the multiple leaf nodes are connected in series via the inner ring optical fiber. The central office node serves as both the starting and ending point for the series connection. The central office node is the type described in the first aspect, and the leaf nodes are the types described in the second aspect. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of a conventional DWDM wavelength division ring network architecture provided in an exemplary embodiment of this application;

[0041] Figure 2 This is a schematic diagram of an optical communication network provided in an exemplary embodiment of this application;

[0042] Figure 3 This is a schematic diagram of the structure of a local node provided in an exemplary embodiment of this application;

[0043] Figure 4 This is a schematic diagram of the structure of a local node provided in an exemplary embodiment of this application;

[0044] Figure 5 This is a schematic diagram of the structure of a local node provided in an exemplary embodiment of this application;

[0045] Figure 6 This is a schematic diagram of the structure of a local node provided in an exemplary embodiment of this application;

[0046] Figure 7 This is a schematic diagram of the structure of a local node provided in an exemplary embodiment of this application;

[0047] Figure 8 This is a schematic diagram of the structure of a local node provided in an exemplary embodiment of this application;

[0048] Figure 9 This is a schematic diagram of the structure of a leaf node provided in an exemplary embodiment of this application;

[0049] Figure 10 This is a schematic diagram of the structure of a leaf node provided in an exemplary embodiment of this application;

[0050] Figure 11 This is a schematic diagram of the structure of a local node provided in an exemplary embodiment of this application;

[0051] Figure 12 This is a schematic diagram of the structure of a leaf node provided in an exemplary embodiment of this application;

[0052] Figure 13 This is a schematic diagram of the structure of a leaf node provided in an exemplary embodiment of this application;

[0053] Figure 14 This is a schematic diagram of the structure of a leaf node provided in an exemplary embodiment of this application;

[0054] Figure 15 This is a schematic diagram of the structure of a leaf node provided in an exemplary embodiment of this application;

[0055] Figure 16 This is a schematic diagram of the structure of a leaf node provided in an exemplary embodiment of this application;

[0056] Figure 17 This is a schematic diagram of an optical communication network provided in an exemplary embodiment of this application;

[0057] Figure 18 This is a schematic diagram of an optical communication network provided in an exemplary embodiment of this application;

[0058] Figure 19 This is a schematic diagram of an optical communication network provided in an exemplary embodiment of this application;

[0059] Figure 20 This is a schematic diagram of an optical communication network provided in an exemplary embodiment of this application.

[0060] Illustration

[0061] 01. Wavelength multiplexing module; 02. Wavelength splitting module; 03. Light source module; 04. Transceiver module; 05. First optical switch; 06. Second optical switch; 07. First up / down waveform module; 08. Second up / down waveform module; 09. First routing module; 10. Second routing module;

[0062] 031, First laser; 032, Second laser; 033, Multiplexing / demultiplexing unit; 034, Switching unit; 035, Demultiplexing unit;

[0063] 041. Receiving unit; 042. Transmitting unit; 043. Processing unit;

[0064] 071, First wavelength division unit; 072, First 1×2 optical coupler; 073, First wavelength multiplexing unit; 074, First 2×1 optical coupler;

[0065] 081, Second Wavelength Division Unit; 082, Second 1×2 Optical Coupler; 083, Second Wavelength Multiplexing Unit; 084, Second 2×1 Optical Coupler. Detailed Implementation

[0066] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0067] In network transmission architecture, the metropolitan area network (MAN) is located at the intersection of the backbone network and the access network, making it a network with a relatively complex application environment in communications. Various types of service data with different requirements are carried directly or indirectly through the MAN, and are aggregated, distributed, and transferred to and from the backbone network within the MAN. Typically, a MAN adopts a dual-fiber ring network architecture, consisting of a central office node and multiple leaf nodes. Starting from and ending at the central office node, the multiple leaf nodes are connected in series to form a ring structure via two optical fibers. Both the outer and inner ring fibers in the dual-fiber system are used for communication between the central office node and the multiple leaf nodes. Because various service data are carried directly or indirectly through the MAN, it needs to transmit a large amount of data. If at least one of the outer or inner ring fibers is interrupted, the MAN will be unable to operate normally.

[0068] In related technologies, metropolitan area networks (MANs) adopt the traditional DWDM (wavelength division multiplexing) ring network architecture. When at least one of the outer and inner ring optical fibers is interrupted, the MAN can still operate normally by switching the main optical module and backup optical module at the central office node and the main optical module and backup optical module at the leaf node.

[0069] Figure 1 A schematic diagram of a traditional DWDM (Distance-Wavelength Division Multiplexing) ring network architecture is shown. See also... Figure 1The ring network architecture includes one central office node and three leaf nodes (leaf node a, leaf node b, and leaf node c). The central office node includes a main optical module and a backup optical module. The main optical module is connected to the outer ring fiber via a first DWDM and to the inner ring fiber via a second DWDM. The backup optical module is connected to the outer ring fiber via a third DWDM and to the inner ring fiber via a second DWDM. Each leaf node includes a main optical module and a backup optical module. The main optical module is connected to the outer ring fiber via a first optical add-drop multiplexer (OADM) and to the inner ring fiber via a second OADM. When there is no interruption in transmission on either the outer or inner ring fiber, the central office node transmits data to the leaf nodes through the main optical module. For example, the main optical module of the central office node outputs signals of multiple wavelengths, each wavelength corresponding to a leaf node. The first DWDM combines the signals of multiple wavelengths to obtain a single signal. One signal is transmitted to the leaf node via the outer ring fiber. The first OADM at the leaf node (e.g., leaf node a) filters out the signal corresponding to its own wavelength from this signal and sends it to the main optical module of the leaf node for demodulation. Signals of other wavelengths corresponding to other nodes in this signal are directly output from the first OADM and transmitted to the next leaf node via the outer ring fiber. The leaf node transmits data to the central office node via the main optical module. For example, the leaf node modulates the data onto the signal light of its corresponding wavelength to obtain a signal of that wavelength. This signal is then combined with signals sent to the central office node by other nodes via a second OADM and output to the inner ring fiber, from where it is transmitted to the central office node. The central office node uses a second DWDM to split the received signal into multiple wavelengths and sends them to its main optical module for demodulation.

[0070] When at least one of the outer and inner ring optical fibers breaks, both the primary and backup optical modules at the central office node remain operational. Figure 1 In this scenario, assuming a fiber break occurs between leaf node b and leaf node c, the leaf node to the left of the fault location uses a backup optical module, while the leaf node to the right of the fault location uses a primary optical module. This ensures uninterrupted communication by using both the primary and backup optical modules.

[0071] As described above, although the traditional DWDM wavelength division ring network architecture can achieve uninterrupted communication, the use of two optical modules and DWDM makes implementation quite difficult. Moreover, the number of lasers in the central office node increases with the number of leaf nodes, making the central office node relatively large.

[0072] This application provides an optical communication network comprising a central office node, multiple leaf nodes, an outer ring optical fiber, and an inner ring optical fiber. The central office node communicates with all leaf nodes using at least one of a first wavelength and a second wavelength. This eliminates the need for a dedicated laser for each leaf node, as is required in a DWDM (Distance-Wave Division Multiplexing) ring network architecture, thus simplifying data transmission and resulting in a smaller central office node size.

[0073] The optical communication network provided in the embodiments of this application is described below. Figure 2 A schematic diagram of an optical communication network is provided. The optical communication network includes a central office node and multiple leaf nodes. The central office node can also be called a central station, central office, local point, or master node, etc., while the leaf nodes can be called leaf stations, access (ACC) stations, or slave nodes, etc. Starting from and ending at the central office node, the central office node and multiple leaf nodes are connected in series via two optical fibers (outer ring fiber and inner ring fiber) to form a dual-fiber ring network architecture. This application embodiment does not limit the number of leaf nodes. Figure 2 Only three leaf nodes (leaf node 1 to leaf node 3) are shown as an example. Figure 2 The leaf node is divided into three parts: two upper and lower wave modules (circles in the leaf node) and a part with transmit and receive functions.

[0074] In the event of a fault in the optical communication network, assume a first leaf node exists between the fault location and the central office node, and a second leaf node exists between the fault location and the central office node on the other side. The central office node uses a first wavelength of light to communicate with the first leaf node, with downlink communication using inner-loop fiber and uplink communication using outer-loop fiber. The central office node uses a second wavelength of light to communicate with the second leaf node, with downlink communication using outer-loop fiber and uplink communication using inner-loop fiber. When the optical communication network is functioning normally, the central office node uses the first wavelength of light to communicate with all leaf nodes, with downlink communication using inner-loop fiber and uplink communication using outer-loop fiber. Alternatively, when the optical communication network is functioning normally, the central office node uses the second wavelength of light to communicate with all leaf nodes, with downlink communication using outer-loop fiber and uplink communication using inner-loop fiber. In this way, communication between the central office node and each leaf node can proceed regardless of whether the optical communication network is faulty or not. Furthermore, the central office node can use at most the first and second wavelengths of light, meaning the number of lasers in the central office node does not need to change with the number of leaf nodes. This simplifies the structure, reduces the size, and lowers the cost of the central office node. Moreover, regardless of whether the optical communication network is faulty or not, the leaf nodes also use a single transceiver module to communicate with the central office node, further simplifying their structure, reducing their size, and lowering their cost.

[0075] In both fault-free and fault-free conditions of the optical communication network, the central office node coherently receives uplink signals from the leaf nodes, and the leaf nodes also coherently receive downlink signals from the central office node. There are two communication methods between the central office node and the leaf nodes: time-division multiplexing and frequency-division multiple access.

[0076] Time-division multiplexing (TDM) refers to each leaf node using the same frequency band to transmit data in different time periods. In TDM, each leaf node is configured with a receive time period and a transmit time period (e.g., the time period of each leaf node is broadcast by the central office node, or the user configures the time period in the leaf node). Although each leaf node can receive the downlink signal transmitted by the central office node, if it is not received in its corresponding time period, it will discard the received downlink signal and only send the uplink signal to the central office node in its corresponding time period.

[0077] Frequency Division Multiple Access (FDMA) refers to a method where each leaf node uses a different frequency band to transmit data. In FDMA, the central office node employs multi-carrier modulation technology, modulating data onto a single wavelength of light to obtain a multi-subcarrier signal for that single wavelength. Different subcarrier signals correspond to different leaf nodes. Each leaf node is configured with a corresponding wavelength. After receiving the multi-subcarrier signal transmitted by the central office node, each leaf node uses its corresponding wavelength of light as its local oscillator to coherently receive the subcarrier signal of its own wavelength. The wavelength corresponding to a leaf node is the center wavelength of the subcarrier signal it is receiving. Furthermore, each leaf node uses its corresponding wavelength of light to transmit the subcarrier signal back to the central office node. It is important to note that single-wavelength light refers to light with a single wavelength value, each subcarrier signal corresponds to one subcarrier, and different subcarrier signals correspond to different subcarriers, each with a different center wavelength. The following description uses FDMA as an example of communication methods.

[0078] The local node and leaf node are described below, starting with the local node.

[0079] Figure 3 This is a schematic diagram of a central office node. The central office node includes a multiplexing module 01, a demultiplexing module 02, a light source module 03, and a transceiver module 04.

[0080] Wavelength multiplexing module 01 and transceiver module 04 are connected via optical fiber, as are wavelength division multiplexing module 02 and transceiver module 04. Wavelength multiplexing module 01 is used to connect to the outer and inner ring optical fibers, and wavelength division multiplexing module 02 is used to connect to the outer and inner ring optical fibers. For example, wavelength multiplexing module 01 includes two input ports and one output port. The two input ports of wavelength multiplexing module 01 are used to connect to the outer and inner ring optical fibers, respectively, and the output port of wavelength multiplexing module 01 is connected to transceiver module 04 via optical fiber. Wavelength division multiplexing module 02 includes one input port and two output ports. The input port of wavelength division multiplexing module 02 is connected to transceiver module 04 via optical fiber, and the two output ports of wavelength division multiplexing module 02 are used to connect to the outer and inner ring optical fibers, respectively. Wavelength multiplexing module 01 can also be called a multiplexer, and wavelength division multiplexing module 02 can also be called a demultiplexer. Light source module 03 is connected to transceiver module 04 via optical fiber.

[0081] The multiplexing module 01 is used to combine two received uplink signals from the outer ring fiber and the inner ring fiber into a single signal, and to send the received uplink signal to the receiving module 04 when it receives an uplink signal from either the outer ring fiber or the inner ring fiber. Here, the uplink signal is the signal sent from the leaf node to the central office node.

[0082] The light source module 03 provides the transceiver module 04 with local oscillator (LO) light and signal light of the same wavelength. The LO light is used for coherent reception in coherent optical communication and can also be called the reference light. The signal light is used to modulate the data to be transmitted in optical communication. The LO light includes at least one of a first wavelength and a second wavelength. For example, in the event of a fault in the optical communication network, both the LO light and the signal light include the first wavelength and the second wavelength. When the optical communication network is functioning normally, both the LO light and the signal light include at least one of the first wavelength and the second wavelength. Both the first wavelength and the second wavelength are single-wavelength lights.

[0083] The transceiver module 04 uses local oscillator light to receive the uplink signal sent by the multiplexing module 01. Furthermore, the transceiver module 04 uses signal light to generate a downlink signal and sends this downlink signal to the demultiplexing module 02.

[0084] When the downlink signal comprises two downlink signals, the wavelength division module 02 splits the downlink signal into two downlink signals and transmits them to the outer ring fiber and the inner ring fiber, respectively. The wavelengths of the two downlink signals belong to the first wavelength and the second wavelength, respectively. When the downlink signal is a single downlink signal, the wavelength division module 02 transmits it to either the outer ring fiber or the inner ring fiber (the specific transmission direction is determined by the wavelength of that single downlink signal).

[0085] The above-mentioned multiplexing module 01 can be any kind of device used for multiplexing, and the demultiplexing module 02 can be any kind of device used for demultiplexing. For example, both the multiplexing module 01 and the demultiplexing module 02 are three-port red and blue band filter devices.

[0086] use Figure 3 The process of the central office node sending downlink signals and receiving uplink signals is as follows, assuming that the optical communication network is functioning correctly.

[0087] The process of a central office node sending downlink signals is as follows: The light source module 03 provides light of a first wavelength to the transceiver module 04; this first wavelength light is the signal light. The transceiver module 04 uses multi-carrier modulation technology to modulate data onto the first wavelength light, obtaining a multi-subcarrier signal of the first wavelength (i.e., the downlink signal of the first wavelength). This multi-subcarrier signal of the first wavelength is then sent to the wavelength division module 02, with each leaf node corresponding to one subcarrier signal. The wavelength division module 02 transmits the multi-subcarrier signal of the first wavelength to the connected inner-loop optical fiber, thus transmitting it to the leaf nodes. All leaf nodes use their corresponding wavelength local oscillator light to receive their own subcarrier signals.

[0088] The process of the central office node receiving the uplink signal is as follows: all leaf nodes use light of the corresponding wavelength to modulate data and generate subcarrier signals. The wavelengths corresponding to all leaf nodes belong to the first wavelength. When the subcarrier signals of all leaf nodes are transmitted to the central office node, they form a multi-subcarrier signal of the first wavelength (i.e., the uplink signal of the first wavelength). The multiplexing module 01 receives this multi-subcarrier signal from the outer ring fiber and sends it to the transceiver module 04. The light source module 03 provides light of the first wavelength to the transceiver module 04. The transceiver module 04 uses the light of the first wavelength as the local oscillator and coherently receives the multi-subcarrier signal. This is an example of communication between the central office node and leaf nodes using light of the first wavelength. Of course, communication can also be carried out using light of the second wavelength. The processing is similar to that of communication using light of the first wavelength, except that uplink communication uses the inner ring fiber and downlink communication uses the outer ring fiber. This will not be elaborated further here.

[0089] In addition, when the optical communication network is functioning correctly, the light source module 03 can also provide the transceiver module 04 with light of the first and second wavelengths. During downlink communication, the transceiver module 04 employs multi-carrier modulation technology, modulating data on the first and second wavelengths to obtain a single signal comprising a multi-subcarrier signal of the first and second wavelengths, with the modulated data on both wavelengths being identical. The transceiver module 04 transmits this single signal to the wavelength division module 02, which then divides it into the first and second wavelength multi-subcarrier signals. Either the first or second wavelength multi-subcarrier signal is output from the central office node for reception by the leaf nodes. Alternatively, both the first and second wavelength multi-subcarrier signals may be output from the central office node, but the leaf nodes may only receive either the first or second wavelength multi-subcarrier signal. During uplink communication, the subcarrier signals transmitted by all leaf nodes constitute the first wavelength multi-subcarrier signal, or the subcarrier signals transmitted by all leaf nodes constitute the second wavelength multi-subcarrier signal. It should be noted here that during uplink and downlink communication, the wavelength of the subcarrier signal that the leaf node can demodulate is the same as the wavelength of the subcarrier signal sent by the leaf node to the central office node, such as both being the first wavelength or both being the second wavelength.

[0090] In the event of a failure in the optical communication network, the process of the central office node sending downlink signals and receiving uplink signals is as follows.

[0091] The process of a central office node transmitting a downlink signal is as follows: The light source module 03 provides the transceiver module 04 with light of a first wavelength and light of a second wavelength, which serve as signal light. The transceiver module 04 modulates data on the first wavelength light to obtain a multi-subcarrier signal of the first wavelength, and modulates data on the second wavelength light to obtain a multi-subcarrier signal of the second wavelength (i.e., the downlink signal of the second wavelength), thus obtaining a single downlink signal comprising the multi-subcarrier signals of the first and second wavelengths. The data modulated on the first and second wavelengths are identical. The transceiver module 04 then transmits this single downlink signal to the wavelength division module 02. The wavelength division module 02 divides this single downlink signal into a multi-subcarrier signal of the first wavelength and a multi-subcarrier signal of the second wavelength, and transmits them through two output ports to the inner and outer ring optical fibers, respectively. For example, the multi-subcarrier signal of the first wavelength is transmitted through the inner ring optical fiber, and the multi-subcarrier signal of the second wavelength is transmitted through the outer ring optical fiber. All leaf nodes use local oscillator light of their corresponding wavelength to receive their own subcarrier signals.

[0092] The process of the central office node receiving the uplink signal is as follows: The first leaf node between the fault location and the central office node uses light of the corresponding wavelength to modulate data and generate subcarrier signals; these wavelengths belong to the first wavelength. The first leaf node sends the generated subcarrier signals to the central office node. The second leaf node between the fault location and the central office node uses light of the corresponding wavelength to modulate data and generate subcarrier signals; these wavelengths belong to the second wavelength. The second leaf node sends the generated subcarrier signals to the central office node. The multi-subcarrier signals of the first wavelength are sent from the outer ring fiber to the multiplexing module 01, and the multi-subcarrier signals of the second wavelength (i.e., the uplink signals of the second wavelength) are sent from the inner ring fiber to the multiplexing module 01. The multiplexing module 01 combines the multi-subcarrier signals of the first and second wavelengths into a single uplink signal. The multiplexing module 01 sends this single uplink signal to the transceiver module 04. The light source module 03 provides the transceiver module 04 with light of the first and second wavelengths; these first and second wavelengths are local oscillator light. After receiving the uplink signal, the transceiver module 04 uses light of the first wavelength and light of the second wavelength as local oscillator light to coherently receive the uplink signal, obtain the data modulated on the multi-subcarrier signal of the first wavelength, and obtain the data modulated on the multi-subcarrier signal of the second wavelength.

[0093] Based on the above description, in the event of a fault in the optical communication network, when leaf nodes on one side of the fault location communicate with the central office node, they use light of the first wavelength to transmit downlink signals through the inner ring fiber and uplink signals through the outer ring fiber. When leaf nodes on the other side of the fault location communicate with the central office node, they use light of the second wavelength to transmit downlink signals through the outer ring fiber and uplink signals through the inner ring fiber. When the optical communication network is functioning normally, when all leaf nodes communicate with the central office node, they use light of the first wavelength to transmit downlink signals through the inner ring fiber and uplink signals through the outer ring fiber; alternatively, all leaf nodes communicate with the central office node using light of the second wavelength to transmit downlink signals through the outer ring fiber and uplink signals through the inner ring fiber.

[0094] based on Figure 3 As shown, the leaf nodes are also configured based on the structure of the local node, enabling the leaf nodes to communicate with the local node.

[0095] For example, an optical communication network failure refers to the inability of the central office node to communicate normally with some leaf nodes in the optical communication network. For example, an optical communication network failure includes two possible scenarios: one is a breakage of at least one fiber in the outer ring or inner ring; the other is a failure of a leaf node. The central office node's procedure for determining whether the optical communication network is faulty is as follows.

[0096] When each leaf node sends a subcarrier signal to the central office node, the central office node determines the number of subcarriers in the received multi-subcarrier signal. If this number is less than the number of leaf nodes, the optical communication network is determined to be faulty. If the number is equal to the number of leaf nodes, the optical communication network is determined not to be faulty.

[0097] Alternatively, the central office node determines whether it has not received subcarrier signals from certain leaf nodes within the target duration. If it has not received subcarrier signals from certain leaf nodes within the target duration, it determines that the optical communication network is faulty; if it has received subcarrier signals from all leaf nodes within the target duration, it determines that the optical communication network is not faulty. The target duration can be flexibly configured, and this application embodiment does not limit it.

[0098] Alternatively, in some cases, the outer and inner ring fibers do not break simultaneously. Assuming the fiber used for uplink communication in the optical communication network is intact, but the fiber used for downlink communication is broken, the central office node cannot transmit downlink signals to the leaf nodes. However, the leaf nodes can send uplink signals to the central office node. When the leaf nodes send uplink signals to the central office node, they carry a fault indication message. Based on this fault indication message, the central office node determines that there is a fault in the optical communication network.

[0099] Alternatively, the central office node receives a message from the monitoring center indicating whether the optical communication network is faulty. The central office node determines whether the optical communication network is faulty based on this message.

[0100] It should be noted that the above four judgment methods are all applicable to frequency division multiple access (FDMA) communication methods, while the latter two methods are applicable to time division multiplexing (TDM) communication methods. When communicating using TDM, the following method can also be used to determine whether the optical communication network is faulty: each leaf node has a fixed transmission time period. If the central office node does not receive the uplink signal from a leaf node during its transmission time period, the optical communication network is determined to be faulty; otherwise, the optical communication network is determined not to be faulty.

[0101] It should also be noted that in optical communication networks, leaf nodes and central office nodes communicate continuously, even without service data, sending signaling messages. Furthermore, in optical communication networks, outer and inner ring fibers are typically installed together; if a fiber break occurs, they usually break together.

[0102] For example, Figure 4This is another schematic diagram of a central office node. The central office node includes two input ports (a first input port and a second input port) and two output ports (a first output port and a second output port). The first and second input ports are used to connect to the outer ring fiber and the inner ring fiber, respectively. The first and second output ports are used to connect to the outer ring fiber and the inner ring fiber, respectively. The two input ports of the multiplexing module 01 are connected to the first and second input ports via optical fibers, respectively. The two output ports of the demultiplexing module 02 are connected to the first and second output ports via optical fibers, respectively. The first and second input ports can transmit signals of a first wavelength, and the second input port and the first output port can transmit signals of a second wavelength.

[0103] For example, Figure 5 This is another schematic diagram of the local node structure. See also... Figure 5 The transceiver module 04 includes a receiving unit 041 and a transmitting unit 042. The receiving unit 041 is used for coherently receiving uplink signals, and the transmitting unit 042 is used for transmitting downlink signals. The receiving unit 041 is connected to the multiplexing module 01 via optical fiber. The transmitting unit 042 is connected to the demultiplexing module 02 via optical fiber. The light source module 03 is connected to the receiving unit 041 via optical fiber, and the light source module 03 provides local oscillator light to the receiving unit 041. The light source module 03 is also connected to the transmitting unit 042 via optical fiber, and the light source module 03 provides signal light to the transmitting unit 042. For example, the output port of the multiplexing module 01 is connected to the input port of the receiving unit 041 via optical fiber, and the output port of the transmitting unit 042 is connected to the input port of the demultiplexing module 02 via optical fiber.

[0104] exist Figure 5 In the illustrated structure, receiving unit 041 receives the signal transmitted by wavelength division multiplexing module 01 based on local oscillator light. For example, receiving unit 041 uses local oscillator light of a first wavelength to receive a multi-subcarrier signal of a first wavelength. Transmitting unit 042 is used to transmit a signal to wavelength division multiplexing module 02 based on signal light. For example, transmitting unit 042 uses signal light of a first wavelength to transmit a multi-subcarrier signal of a first wavelength.

[0105] For example, to simplify the control logic of the central office node, in both faulty and non-faulty conditions of the optical communication network, the light source module 03 transmits light of the first wavelength and light of the second wavelength to the transceiver module 04; that is, both the local oscillator light and the signal light include light of the first wavelength and light of the second wavelength. In this case, the light source module 03 includes a first laser 031, a second laser 032, and a multiplexing / demultiplexing unit 033, see [link to relevant documentation]. Figure 6 The structure of the local node is shown.

[0106] exist Figure 6In this embodiment, a first laser 031 is connected to a multiplexing / demultiplexing unit 033 via optical fiber, and a second laser 032 is also connected to the multiplexing / demultiplexing unit 033 via optical fiber. The first laser 031 outputs light of a first wavelength and sends it to the multiplexing / demultiplexing unit 033. The second laser 032 outputs light of a second wavelength and sends it to the multiplexing / demultiplexing unit 033. The multiplexing / demultiplexing unit 033 receives the first and second wavelengths of light, combines them into a single beam, and then splits this single beam into two beams. Each beam includes both the first and second wavelengths of light, and the power of the two beams can be the same or different; this embodiment does not limit this. The multiplexing / demultiplexing unit 033 sends one beam to a receiving unit 041 as its local oscillator, and sends the other beam to a transmitting unit 042 as its signal light.

[0107] For example, the multiplexing / splitting unit 033 is implemented using a 2×2 optical coupler, or using a multiplexing unit and a 1×2 optical coupler. The multiplexing unit combines the light of the first wavelength and the light of the second wavelength into a single beam, and the 1×2 optical coupler splits this single beam into two beams. Here, the multiplexing unit is a three-port red-green-blue band filter device.

[0108] In this way, with the above structure, the light source module 03 provides light of the first wavelength and light of the second wavelength to the transceiver module 04 regardless of whether the optical communication network is faulty or not. When the optical communication network changes from faulty to non-faulty or from non-faulty to faulty, there is no need to control the light source module 03, which is easy to implement.

[0109] It should be noted that, as described above, in the event of a fault in the optical communication network, the light source module 03 needs to provide the transceiver module 04 with light of both the first and second wavelengths. However, when the optical communication network is functioning normally, the transceiver module 04 only needs either the first or second wavelength of light. Figure 6 In the light source module 03 shown, although the light source module 03 provides light of the first wavelength and light of the second wavelength to the transceiver module 04, each leaf node only sends either the first wavelength uplink signal or the second wavelength uplink signal to the central office node. Alternatively, although each leaf node sends both the first and second wavelength uplink signals, the receiving module 04 of the central office node only receives either the first wavelength uplink signal or the second wavelength uplink signal. Furthermore, although the central office node sends both the first and second wavelength downlink signals, it can control the leaf nodes to receive either the first wavelength downlink signal or the second wavelength downlink signal, or control one of the first wavelength downlink signal or the second wavelength downlink signal to be output from the central office node.

[0110] It should also be noted that, Figure 6 The light source module 03 shown is one possible structure, and this application does not limit its implementation. For example, the light source module 03 may also include a first sub-module and a second sub-module, where the first sub-module provides local oscillator light to the receiving unit 041, and the second sub-module provides signal light to the transmitting unit 042. As another example, in another implementation of the light source module 03, the light source module 03 includes a first laser 031, a second laser 032, a multiplexing / demultiplexing unit 033, and an optical switch, with the optical switch located between the first laser 031 and the multiplexing / demultiplexing unit 033. When the optical communication network is functioning correctly, the optical switch is open, and only the second laser 032 is connected to the multiplexing / demultiplexing unit 033, allowing the central office node to communicate using light of the second wavelength. When the optical communication network fails, the optical switch is closed, and the first laser 031, the second laser 032, and the multiplexing / demultiplexing unit 033 are connected, allowing the central office node to communicate using light of the first wavelength and light of the second wavelength.

[0111] For example, in Figure 6 In the light source module 03 shown, when the optical communication network is functioning correctly, the light source module 03 also provides light of the first wavelength and the second wavelength to the receiving unit 041 and the transmitting unit 042. The transmitting unit 042 will then output a multi-subcarrier signal of the first wavelength and a multi-subcarrier signal of the second wavelength, with the same modulated data on both signals. However, when the optical communication network is functioning correctly, the leaf node only needs to receive either the first wavelength or the second wavelength multi-subcarrier signal; it does not need to receive both. Therefore, when the central office node and the leaf node use optical communication of the first wavelength, the control prevents the output of the second wavelength multi-subcarrier signal from the central office node, and vice versa. Furthermore, assuming the optical communication network is functioning correctly, leaf nodes can communicate with the central office node using either the first or second wavelength of light. However, if the leaf nodes could also output subcarrier signals of both the first and second wavelengths, the central office node would repeatedly receive modulated data from the subcarrier signals. Therefore, when the central office node and leaf nodes use the first wavelength for optical communication, the control prevents the second wavelength multi-subcarrier signal from being input to the receiving unit 041; conversely, when the central office node and leaf nodes use the second wavelength for optical communication, the control prevents the first wavelength multi-subcarrier signal from being input to the receiving unit 041. Based on this, the following is provided: Figure 7 The structure of the local node is shown.

[0112] See Figure 7The central office node also includes a first optical switch 05 and a second optical switch 06. When the optical communication network is functioning correctly, both the first optical switch 05 and the second optical switch 06 are in the open state; when the optical communication network fails, both are in the closed state. The positions of the first optical switch 05 and the second optical switch 06 are related to the wavelength used for communication when the optical communication network is functioning correctly.

[0113] For example, when the optical communication network is functioning correctly, and the central office node and leaf nodes use optical communication with a first wavelength, a first optical switch 05 is positioned between the second input port of the multiplexing module 01 and the inner ring fiber, and a second optical switch 06 is positioned between the second output port of the wavelength division module 02 and the outer ring fiber. Both the second input port and the second output port are used to transmit signals of the second wavelength. Alternatively, when the central office node and leaf nodes use optical communication with a second wavelength, the first optical switch 05 is positioned between the first input port of the multiplexing module 01 and the outer ring fiber, and the second optical switch 06 is positioned between the first output port of the wavelength division module 02 and the inner ring fiber. Both the first input port and the first output port are used to transmit signals of the first wavelength.

[0114] exist Figure 7 The diagram illustrates the scenario where, in the absence of a fault in the optical communication network, the central office node and leaf nodes use optical communication with the second wavelength. Thus, although the transmitting unit 042 outputs both a first-wavelength and a second-wavelength multi-subcarrier signal, it only outputs the second-wavelength multi-subcarrier signal to the leaf nodes. Furthermore, it ensures that when the same leaf node transmits both a first-wavelength and a second-wavelength subcarrier signal, it only receives either the first-wavelength or the second-wavelength subcarrier signal, preventing duplicate reception.

[0115] In the event of a fault in the optical communication network, the central office node outputs signals of two wavelengths. The first optical switch 05 and the second optical switch 06 are in the closed state. In this way, the multi-subcarrier signal of the first wavelength and the multi-subcarrier signal of the second wavelength output by the transmitting unit 042 can be output. Moreover, when the subcarrier signal of the first wavelength and the subcarrier signal of the second wavelength are sent by different leaf nodes, the central office node can also receive them.

[0116] Optionally, the first optical switch 05 and the second optical switch 06 are electrically connected to the processing unit 043 mentioned later. The processing unit 043 can control the first optical switch 05 and the second optical switch 06. In the event of a fault in the optical communication network, the processing unit 043 controls the first optical switch 05 and the second optical switch 06 to close; in the event that the optical communication network is not faulty, the processing unit 043 controls the first optical switch 05 and the second optical switch 06 to open.

[0117] Optionally, the central office node also includes a control unit that controls the first optical switch 05 and the second optical switch 06.

[0118] In another implementation of the light source module 03, the wavelengths of the light transmitted by the light source module 03 to the transceiver module 04 differ depending on whether the optical communication network is faulty or not. When the optical communication network is faulty, the light source module 03 transmits light of a first wavelength and light of a second wavelength to the transceiver module 04. When the optical communication network is not faulty, the light source module 03 transmits either light of the first wavelength or light of the second wavelength to the transceiver module 04. To achieve this function, the transceiver module 04 also includes a processing unit 043, see [link to relevant documentation]. Figure 8 The provided schematic diagram of the central office node shows that the processing unit 043 is a digital signal processor (DSP), etc. In the event of a fault in the optical communication network, the processing unit 043 sends control commands to the light source module 03, causing the light source module 03 to send light of a first wavelength and a second wavelength to the receiving unit 041, and also causing the light source module 03 to send light of the first wavelength and a second wavelength to the transmitting unit 042. In the event of a normal optical communication network, the processing unit 043 sends control commands to the light source module 03, causing the light source module 03 to send light of either the first wavelength or the second wavelength to both the receiving unit 041 and the transmitting unit 042.

[0119] For example, the light source module 03 also adopts... Figure 5 The structure of the light source module 03 shown is as follows: When the optical communication network is functioning correctly, the processing unit 043 controls the first laser 031 to output light of a first wavelength and controls the second laser 032 to not output light. The first wavelength light is split into two beams by the multiplexing / demultiplexing unit 033, which are then sent to the receiving unit 041 and the transmitting unit 042, respectively. Alternatively, the processing unit 043 controls the second laser 032 to output light of a second wavelength and controls the first laser 031 to not output light. The second wavelength light is split into two beams by the multiplexing / demultiplexing unit 033, which are then sent to the receiving unit 041 and the transmitting unit 042, respectively. When the optical communication network fails, the processing unit 043 controls the first laser 031 to output light of a first wavelength and the second laser 032 to output light of a second wavelength. The first and second wavelength lights are combined by the multiplexing / demultiplexing unit 033 and then split into two beams, which are then sent to the receiving unit 041 and the transmitting unit 042, respectively.

[0120] exist Figure 8In the structure shown, by setting up processing unit 043, either the first laser 031 or the second laser 032 can be turned off when the optical communication network is functioning normally, thereby reducing energy consumption. Furthermore, when the optical communication network is functioning normally, in order to ensure that the first laser 031 and the second laser 032 have comparable usage time, the use of the first laser 031 and the second laser 032 can be periodically switched. For example, the period could be one month.

[0121] Optionally, the processing unit 043 is connected to the receiving unit 041 and the transmitting unit 042 respectively. The processing unit 043 is used to control the receiving unit 041 to receive and to control the transmitting unit 042 to transmit.

[0122] For example, when the light source module 03 provides light of the first wavelength and the second wavelength as local oscillator light, if the multi-subcarrier signal transmitted downlink through the outer ring fiber is input again from the input port connected to the outer ring fiber, it will also be coherently received by the central office node based on the local oscillator light. The input port of the multiplexer module 01 connected to the outer ring fiber provides filtering functionality, preventing the downlink multi-subcarrier signal from entering the transceiver module 04. Similarly, if the multi-subcarrier signal transmitted downlink through the inner ring fiber is input again from the input port connected to the inner ring fiber, it will also be coherently received by the central office node based on the local oscillator light. The input port of the multiplexer module 01 connected to the inner ring fiber provides filtering functionality, preventing the downlink multi-subcarrier signal from entering the transceiver module 04. This prevents the multi-subcarrier signal output by the central office node from being received by the central office node itself.

[0123] The structure of the central office node has been described above. The structure of the leaf node will be described next. The structure of each leaf node in the optical communication network is the same. The leaf node described below refers to any leaf node in the optical communication network.

[0124] Figure 9 This is a schematic diagram of a leaf node structure. See also... Figure 9 The leaf node includes a light source module 03, a first up / down wave module 07, a transceiver module 04, and a second up / down wave module 08. The light source module 03 and the transceiver module 04 are connected via optical fiber. The first up / down wave module 07 is used to connect to a first optical fiber, and the second up / down wave module 08 is used to connect to a second optical fiber. Both the first and second optical fibers are connected to the central office node. The transceiver module 04 is connected to the first up / down wave module 07 and the second up / down wave module 08 via optical fiber.

[0125] The light source module 03 provides the transceiver module 04 with local oscillator light and signal light of the same wavelength. Both the local oscillator light and the signal light include at least a third wavelength. The local oscillator light is used for coherent reception in coherent optical communication, and the signal light is used to modulate the data to be transmitted in optical communication. The central office node sends a first downlink signal from the first optical fiber to the leaf node. The first uplink / downlink module 07 is connected to the first optical fiber, receives the first downlink signal from the first optical fiber, splits the first downlink signal into two downlink signals, and sends them to the transceiver module 04 and the first optical fiber, respectively. Here, the first uplink / downlink module 07 has two ports, which receive data from the first optical fiber and send data to the first optical fiber, respectively. The transceiver module 04 receives the downlink signal sent by the first uplink / downlink module 07, demodulates the downlink signal using the local oscillator light provided by the light source module 03, and obtains the data modulated on the downlink signal of the third wavelength. In this way, the leaf node receives the data sent by the central office node.

[0126] The transceiver module 04 can also receive the signal light provided by the light source module 03, modulate the data to be sent to the central office node onto the signal light, and generate at least a third wavelength uplink signal. The transceiver module 04 sends the generated signal to the second uplink / downlink module 08. The second uplink / downlink module 08 can receive uplink signals sent by other leaf nodes from the second optical fiber, merge the uplink signal with the third wavelength uplink signal to obtain a single uplink signal, and output the single uplink signal to the second optical fiber. Although the first leaf node of the uplink communication is connected to the second optical fiber, it will not receive the uplink signal. In this way, the second uplink / downlink module 08 can send data to the central office node.

[0127] The second up-and-down wave module 08 here has two ports, which are used to receive data from the second optical fiber and send data to the second optical fiber, respectively.

[0128] As can be seen from the above description, the leaf node only needs to include one transceiver module 04 to communicate with the local node, which simplifies the data transmission process.

[0129] It should be noted that in frequency division multiple access (FDMA), the third wavelength is the center wavelength of a subcarrier obtained by modulating data onto the first or second wavelength of light mentioned earlier. In time division multiplexing (TDM), the third wavelength can be the same as the first or second wavelength. In FDMA, the downlink signal of the third wavelength is the subcarrier signal with the third wavelength as its center, and the uplink signal of the third wavelength is also the subcarrier signal with the third wavelength as its center. The following explanation will use FDMA as an example.

[0130] For example, when a leaf node communicates with a central node, two links are used for communication, see [link to example]. Figure 10The leaf node shown has two communication links. One link uses the first uplink / downlink module 07 for uplink communication and the second uplink / downlink module 08 for downlink communication. The other link uses the first uplink / downlink module 07 for downlink communication and the second uplink / downlink module 08 for uplink communication. One of these links is the target communication link, which is the link through which the leaf node communicates with the central office node when the optical communication network is functioning correctly.

[0131] exist Figure 10 The leaf node also includes a first routing module 09 and a second routing module 10. The transceiver module 04 is connected to the first routing module 09 via optical fiber, and the transceiver module 04 is connected to the second routing module 10 via optical fiber. In the event of a target communication link interruption, the process of communication between the leaf node and the central office node is as follows.

[0132] The local oscillator light and signal light provided by the light source module 03 to the transceiver module 04 are light of the fourth wavelength. In frequency division multiple access, the fourth wavelength is the center wavelength of a certain subcarrier obtained by modulating data with the first wavelength or the second wavelength mentioned above. In time division multiplexing, the fourth wavelength can be the same as the first wavelength or the second wavelength. The third wavelength is different from the fourth wavelength.

[0133] The central office node transmits a second downlink signal from the second optical fiber to the leaf node. The second uplink / downlink module 08 is connected to the second optical fiber. The second uplink / downlink module 08 receives the second downlink signal from the second optical fiber, splits it into two downlink signals, and transmits them to the first routing module 09 and the second optical fiber, respectively. The first routing module 09 receives the downlink signal transmitted by the second uplink / downlink module 08 and transmits it to the transceiver module 04. The transceiver module 04 receives the downlink signal transmitted by the first routing module 09 and uses the local oscillator light provided by the light source module 03 to demodulate the data on the fourth wavelength downlink signal within this downlink signal.

[0134] The transceiver module 04 can also receive the signal light provided by the light source module 03, modulate the data to be sent to the central office node onto the signal light, and generate at least a fourth wavelength uplink signal. The transceiver module 04 sends the generated signal to the second routing module 10. The second routing module 10 receives the signal sent by the transceiver module 04 and sends the fourth wavelength uplink signal in the signal to the first uplink / downlink module 07. The first uplink / downlink module 07 can receive uplink signals sent by other leaf nodes from the first optical fiber, and after combining the uplink signal received from the first optical fiber with the fourth wavelength uplink signal, outputs it to the first optical fiber. Here, although the first leaf node of the uplink communication is connected to the first optical fiber, it will not receive the uplink signal.

[0135] Based on the above description, in the event of a target communication link interruption, the leaf node can communicate with the central office node.

[0136] It should be noted that in frequency division multiple access (FDMA), the fourth wavelength is the center wavelength of a subcarrier obtained by modulating data onto the first or second wavelength of light mentioned earlier. In time division multiplexing (TDM), the fourth wavelength can be the same as the first or second wavelength. In FDMA, the downlink signal of the fourth wavelength is the subcarrier signal with the fourth wavelength as its center, and the uplink signal of the fourth wavelength is the subcarrier signal with the fourth wavelength as its center.

[0137] The process of communication between the leaf node and the local node is as follows, provided that the target communication link is not interrupted.

[0138] The central office node transmits a first downlink signal from the first optical fiber to the leaf node. A first uplink / downlink module 07 is connected to the first optical fiber. The first uplink / downlink module 07 receives the first downlink signal from the first optical fiber, splits it into two downlink signals, and transmits them to the first routing module 09 and the first optical fiber, respectively. The first routing module 09 receives the downlink signal transmitted by the first uplink / downlink module 07 and transmits it to the transceiver module 04. The transceiver module 04 receives the downlink signal transmitted by the first routing module 09 and uses the local oscillator light provided by the light source module 03 to demodulate the data on the third wavelength downlink signal within this downlink signal.

[0139] The transceiver module 04 can also receive the signal light provided by the light source module 03, modulate the data to be transmitted to the central office node onto the signal light, and generate at least a third wavelength uplink signal. The transceiver module 04 sends the generated signal to the second routing module 10. The second routing module 10 receives the signal sent by the transceiver module 04 and sends the third wavelength uplink signal in the signal to the second uplink / downlink module 08. The second uplink / downlink module 08 can receive uplink signals sent by other leaf nodes on the second optical fiber, and after combining the uplink signal received from the second optical fiber with the third wavelength uplink signal, outputs it to the second optical fiber.

[0140] In this way, the leaf node can communicate with the central office node if the target communication link is not interrupted.

[0141] For example, the first routing module 09 is the multiplexing module 01 mentioned above, and the second routing module 10 is the demultiplexing module 02 mentioned above. Both the first routing module 09 and the second routing module 10 are connected to the transceiver module 04 via optical fiber. The first routing module 09 is connected to the first up-and-down wave module 07 and the second up-and-down wave module 08 via optical fiber, and the second routing module 10 is connected to the first up-and-down wave module 07 and the second up-and-down wave module 08 via optical fiber.

[0142] Alternatively, both the first routing module 09 and the second routing module 10 can be optical switches. Both the first routing module 09 and the second routing module 10 are connected to the transceiver module 04 via optical fiber. In the event of an interruption of the target communication link, the first routing module 09 is connected to the second up / down module 08 via optical fiber, and the second routing module 10 is connected to the first up / down module 07 via optical fiber. In the event that the target communication link is not interrupted, the first routing module 09 is connected to the first up / down module 07 via optical fiber, and the second routing module 10 is connected to the second up / down module 08 via optical fiber.

[0143] As described above, both the first up-and-down waveform module 07 and the second up-and-down waveform module 08 include four ports: a direct input port, a direct output port, an up-wave input port, and a down-wave output port. The down-wave output port is used to output the signal received by the leaf node to the first routing module 09. The up-wave input port is used for the signal sent to the central office node by the second routing module 10. The direct output port is used to output other signals after the down-wave signal. The direct input port is used to receive signals sent by adjacent nodes (leaf nodes or central office nodes). The first routing module 09 is connected to the down-wave output port of the first up-and-down waveform module 07 via optical fiber, and the first routing module 09 is also connected to the down-wave output port of the second up-and-down waveform module 08 via optical fiber. The second routing module 10 is connected to the up-wave input port of the first up-and-down waveform module 07 via optical fiber, and the second routing module 10 is also connected to the up-wave input port of the second up-and-down waveform module 08 via optical fiber. The direct input port and direct output port of the first up-and-down wave module 07 are used to connect to the first optical fiber, and the direct input port and direct output port of the second up-and-down wave module 08 are used to connect to the second optical fiber.

[0144] For example, the first optical fiber is an outer ring fiber, and the second optical fiber is an inner ring fiber. Alternatively, the first optical fiber is an inner ring fiber, and the second optical fiber is an outer ring fiber. Specifically, the type of the first and second optical fibers depends on the wavelength of the downlink signal transmitted by the central office node. For instance, if the central office node uses light of a first wavelength to transmit downlink signals from the inner ring fiber, and the leaf node uses light of a third wavelength to transmit uplink signals from the outer ring fiber, then the first optical fiber is an inner ring fiber, and the second optical fiber is an outer ring fiber.

[0145] For example, the process of determining whether the target communication link is interrupted is as follows.

[0146] Assuming the fiber used for downlink communication in an optical communication network is disconnected, the leaf node determines whether a downlink signal has been received within the target time period. If no downlink signal is received within the target time period, it is determined that the target communication link is interrupted, and the leaf node automatically switches to another wavelength for communication; otherwise, it is determined that the target communication link is not interrupted.

[0147] Alternatively, assuming the fiber used for downlink communication in the optical communication network is intact, but the fiber used for uplink communication is broken, the central office node, based on the absence of subcarrier signals from certain leaf nodes within a target time period, determines that the optical communication network is faulty. It then sends a fault indication message to these leaf nodes using both the first and second wavelength downlink signals. Upon receiving this message, the leaf nodes confirm that the target communication link is interrupted. The reason the central office node sends the fault indication message using both the first and second wavelength downlink signals is that it cannot determine whether the fiber used for downlink communication is broken. Therefore, sending the fault indication message using both wavelengths ensures that the leaf nodes can receive it regardless of whether they have switched wavelengths or not.

[0148] These are just two ways to determine whether the target communication link is interrupted, and this application embodiment does not limit them.

[0149] It should be noted that in optical communication networks, it's possible that some leaf nodes determine the target communication link is interrupted, while others determine it is not interrupted; or all leaf nodes may determine the target communication link is interrupted, or all leaf nodes may determine it is not interrupted. For example, if a fiber is broken between the central office node and a directly connected leaf node, if that leaf node is the first leaf node through which the central office node's downlink communication passes (i.e., the last leaf node through which its uplink communication passes), then all leaf nodes will determine the target communication link is interrupted. If that leaf node is the last leaf node through which the central office node's downlink communication passes (i.e., the first leaf node through which its uplink communication passes), then all leaf nodes will determine the target communication link is not interrupted. When a fiber is broken between any two leaf nodes, the leaf nodes between one of these two leaf nodes and the central office node will determine the target communication link is not interrupted, while the remaining leaf nodes will determine the target communication link is interrupted.

[0150] For example, a leaf node includes two input ports (a first input port and a second input port) and two output ports (a first output port and a second output port), see [link to relevant documentation]. Figure 11 The first input port and the second input port are used to connect to the first optical fiber and the second optical fiber, respectively. The first output port and the second output port are used to connect to the first optical fiber and the second optical fiber, respectively. The through input port of the first up-and-down wave module 07 is connected to the first input port via an optical fiber, and the through output port of the first up-and-down wave module 07 is connected to the first output port via an optical fiber. The through input port of the second up-and-down wave module 08 is connected to the second input port via an optical fiber, and the through output port of the second up-and-down wave module 08 is connected to the second output port via an optical fiber.

[0151] For example, Figure 12This is another structural diagram of a leaf node. See also Figure 12 The transceiver module 04 includes a receiving unit 041 and a transmitting unit 042. A light source module 03 is connected to the receiving unit 041 via optical fiber, providing local oscillator light to the receiving unit 041. The light source module 03 is also connected to the transmitting unit 042 via optical fiber, providing signal light to the transmitting unit 042. The receiving unit 041 is connected to the first routing module 09 via optical fiber. The transmitting unit 042 is connected to the second routing module 10 via optical fiber. For example, the input port of the receiving unit 041 is connected to the output port of the first routing module 09 via optical fiber, and the output port of the transmitting unit 042 is connected to the input port of the second routing module 10 via optical fiber.

[0152] When the target communication link is uninterrupted, the receiving unit 041 uses at least a third wavelength of local oscillator light to demodulate the data on the third wavelength subcarrier signal from the received downlink signal. The transmitting unit 042 uses at least a third wavelength of signal light to modulate the transmitted data onto the third wavelength light, generating a third wavelength subcarrier signal, and transmits the generated signal to the second routing module 10. When the target communication link is interrupted, the receiving unit 041 uses at least a fourth wavelength of local oscillator light to demodulate the data on the fourth wavelength subcarrier signal from the received downlink signal. The transmitting unit 042 uses at least a fourth wavelength of signal light to modulate the transmitted data onto the fourth wavelength light, generating a fourth wavelength subcarrier signal, and transmits the generated signal to the second routing module 10.

[0153] For example, to simplify the control logic, in both uninterrupted and interrupted target communication links, the light source module 03 transmits light of the third wavelength and the fourth wavelength to the transceiver module 04; that is, both the local oscillator light and the signal light include light of the third wavelength and the fourth wavelength. In this case, the light source module 03 includes a first laser 031, a second laser 032, and a multiplexing / demultiplexing unit 033, see [link to relevant documentation]. Figure 13 The diagram shows the structure of a leaf node.

[0154] exist Figure 13In this embodiment, the first laser 031 is connected to the multiplexing / demultiplexing unit 033 via optical fiber, and the second laser 032 is also connected to the multiplexing / demultiplexing unit 033 via optical fiber. The first laser 031 outputs light of a third wavelength and sends this light to the multiplexing / demultiplexing unit 033. The second laser 032 outputs light of a fourth wavelength and sends this light to the multiplexing / demultiplexing unit 033. The multiplexing / demultiplexing unit 033 receives the third and fourth wavelengths of light, combines them into a single beam, and then splits this beam into two beams, each containing both the third and fourth wavelengths. The power of the two beams can be the same or different; this embodiment does not limit this. The multiplexing / demultiplexing unit 033 sends one beam to the receiving unit 041 as its local oscillator and the other beam to the transmitting unit 042 as its signal beam.

[0155] For example, the multiplexing / demultiplexing unit 033 is implemented using a 2×2 optical coupler, or using a multiplexing unit and a 1×2 optical coupler. The multiplexing unit combines the light of the third wavelength and the light of the fourth wavelength into a single beam, and the 1×2 optical coupler splits this single beam into two beams. Here, the multiplexing unit is a three-port red-green-blue band filter device.

[0156] In this way, with the above structure, the light source module 03 provides the transceiver module 04 with light of the third wavelength and the fourth wavelength regardless of whether the target communication link is uninterrupted or interrupted. There is no need to control the light source module 03 when the target communication link changes from uninterrupted to interrupted, or from interrupted to uninterrupted. The implementation is simple.

[0157] For example, in another implementation, the wavelengths of the light transmitted by the light source module 03 to the transceiver module 04 are different depending on whether the target communication link is uninterrupted or interrupted. When the target communication link is uninterrupted, the light source module 03 transmits light of a third wavelength to the transceiver module 04. When the target communication link is interrupted, the light source module 03 transmits light of a fourth wavelength to the transceiver module 04. In this case, the light source module 03 includes a first laser 031, a second laser 032, a switching unit 034, and a wavelength division unit 035, see [link to relevant documentation]. Figure 14 The diagram shows the structure of a leaf node.

[0158] See Figure 14The switching unit 034 and the wavelength division unit 035 are connected via optical fiber. The switching unit 034 can be an optical switch, etc. The first laser 031 outputs light of a third wavelength, and the second laser 032 outputs light of a fourth wavelength. When the target communication link is not interrupted, the switching unit 034 switches to connect with the first laser 031, so that the third wavelength light is output to the wavelength division unit 035. The wavelength division unit 035 splits the third wavelength light into two paths, which are transmitted to the receiving unit 041 and the transmitting unit 042, respectively. When the target communication link is interrupted, the switching unit 034 switches to connect with the second laser 032, so that the fourth wavelength light is output to the wavelength division unit 035. The wavelength division unit 035 splits the fourth wavelength light into two paths, which are transmitted to the receiving unit 041 and the transmitting unit 042, respectively. This embodiment does not limit the power ratio of the two paths output by the wavelength division unit 035.

[0159] Optionally, the transceiver module 04 also includes a processing unit 043. The processing unit 043 is electrically connected to the switching unit 034. The processing unit 043 can control the switching unit 034. When the target communication link is not interrupted, the processing unit 043 controls the switching unit 034 to switch to connect with the first laser 031. When the target communication link is interrupted, the processing unit 043 controls the switching unit 034 to switch to connect with the second laser 032.

[0160] Optionally, the leaf node also includes a control component that controls the switching unit 034 in the same way that the processing unit 043 controls the switching unit 034.

[0161] It should be noted that the central office node can broadcast the wavelength to be used when the target communication link is not interrupted to each leaf node, and each leaf node can control the laser to be connected by the switching unit 034 based on this.

[0162] For example, both the first uplink / downlink module 07 and the second uplink / downlink module 08 are 2×2 optical couplers. Thus, since the 2×2 optical coupler combines the two input downlink signals and then splits the combined downlink signal into two downlink signals based on whether their power is the same or different, rather than dividing them according to wavelength, the implementation of the leaf nodes is relatively simple.

[0163] For example, when both the first up-and-down wave module 07 and the second up-and-down wave module 08 are 2×2 optical couplers, in order to prevent the signal input from the up-wave from being returned to the receiving unit 041 through the down-wave output, the following processing is performed.

[0164] The first port of the first routing module 09 filters the signal input from the first up-down wave module 07. This first port is the port in the first routing module 09 connected to the first up-down wave module 07. The second port of the first routing module 09 filters the signal input from the second up-down wave module 08. This second port is the port in the second routing module 10 connected to the second up-down wave module 08. For example, when the first up-down wave module 07 has an up-down wave input, assuming the up-down wave input of the first up-down wave module 07 is a subcarrier signal of the fourth wavelength, the uplink signal of the second wavelength directly input and the subcarrier signal of the fourth wavelength are combined in a 2×2 optical coupler, and then split into two optical paths according to power, outputting to the receiving unit 041 and the outer ring optical fiber respectively. In this way, the up-down wave input of the fourth wavelength subcarrier signal will return to the receiving unit 041, and since the receiving unit 041 receives the local oscillator light of the fourth wavelength, the receiving unit 041 can demodulate the data on the fourth wavelength subcarrier signal. Using the scheme of this application, the signal of the fourth wavelength is filtered at the first port of the first routing module 09, so that the signal of the fourth wavelength is not input to the receiving unit 041. Similarly, when there is an upper-wave input in the second up-down-wave module 08, assuming that the upper-wave input of the second up-down-wave module 08 is a subcarrier signal of the third wavelength, in order to prevent the receiving unit 041 from receiving the upper-wave input third-wavelength subcarrier signal, the signal of the third wavelength is filtered at the second port of the first routing module 09, so that the third-wavelength subcarrier signal is not input to the receiving unit 041.

[0165] For example, in order to make the power of the down-wave output of the first up-wave module 07 configurable with the power of the through output, the first up-wave module 07 includes a first split-wave unit 071, a first 1×2 optocoupler 072, a first multiplexing unit 073, and a first 2×1 optocoupler 074, see [link to documentation]. Figure 15 The diagram shows the structure of a leaf node.

[0166] See Figure 15 The input port of the first wavelength division unit 071 is connected to the first optical fiber. One output port of the first wavelength division unit 071 is connected to the input port of the first 1×2 optical coupler 072 via an optical fiber, and the other output port is connected to one input port of the first 2×1 optical coupler 074 via an optical fiber. One output port of the first 1×2 optical coupler 072 is connected to one input port of the first wavelength multiplexing unit 073 via an optical fiber, and the other output port is connected to the first routing module 09 via an optical fiber. The other input port of the first 2×1 optical coupler 074 is connected to the second routing module 10 via an optical fiber, and the output port of the first 2×1 optical coupler 074 is connected to the other input port of the first wavelength multiplexing unit 073 via an optical fiber. The first wavelength multiplexing unit 073 is connected to the first optical fiber.

[0167] When the target communication link is uninterrupted, the first up-and-down module 07 is used for down-wave, and the two output ports of the first down-wave unit 071 are used to output the first wavelength signal and the second wavelength signal, respectively. Assuming the first optical fiber connected to the first down-wave unit 071 is used to input the first wavelength multi-subcarrier signal, one output port of the first down-wave unit 071 outputs the first wavelength multi-subcarrier signal, while the other output port does not output. The first down-wave unit 071 outputs the first wavelength multi-subcarrier signal to the first 1×2 optical coupler 072. The first 2×1 optical coupler 074 has no input, and the first 1×2 optical coupler 072 splits the first wavelength multi-subcarrier signal into two paths, outputting them to the first multiplexing unit 073 and the first routing module 09, respectively. The first routing module 09 transmits the received signal to the receiving unit 041 in the transceiver module 04. The first multiplexing unit 073 outputs the received first wavelength multi-subcarrier signal directly. Here, by configuring the power of the two outputs of the first 1×2 optical coupler 072, the power output to the first multiplexing unit 073 is higher than the power output to the receiving unit 041. In this way, the power of the direct output signal is higher than the power of the next output signal, so that when it is transmitted to the leaf node at the end, the power of the next output signal received by the leaf node is also relatively high.

[0168] In the event of a target communication link interruption, the first up-wave module 07 is used for up-wave processing, and the two output ports of the first down-wave unit 071 are used to output signals of the first wavelength and the second wavelength, respectively. Assuming the first optical fiber connected to the first down-wave unit 071 is used to input the second wavelength multi-subcarrier signal, one output port of the first down-wave unit 071 outputs the second wavelength multi-subcarrier signal, while the other output port does not output. The first down-wave unit 071 outputs the second wavelength multi-subcarrier signal to one input port of the first 2×1 optical coupler 074, while the first 1×2 optical coupler 072 has no input. The transmitting unit 042 in the transceiver module 04 sends the generated signal to the second routing module 10, which in turn inputs a fourth wavelength subcarrier signal to the up-wave input port of the first 2×1 optical coupler 074. The first 2×1 optical coupler 074 combines the fourth wavelength subcarrier signal with the directly input second wavelength subcarrier signal into a single path and sends it to the first multiplexing unit 073. The first multiplexing unit 073 outputs the second wavelength multi-subcarrier signal. In this way, not only can the up-wave be achieved, but the subcarrier signal input by the up-wave will also not return to the receiving unit 041.

[0169] It should be noted that, in Figure 15 In the middle, the second upper and lower wave module 08 can be adopted Figure 15The second up-and-down wave module 08 shown can also be a 2×2 optical coupler. Furthermore, the output power of the two output ports of the first 1×2 optical coupler 072 is flexibly configurable, and the specific ratio is not limited in this embodiment.

[0170] For example, in order to make the power output of the lower-wave module 08 different from the power output of the direct-through module, the second lower-wave module 08 includes a second wavelength division unit 081, a second 1×2 optical coupler 082, a second wavelength combination unit 083, and a second 2×1 optical coupler 084. See [link to documentation]. Figure 16 The diagram shows the structure of a leaf node.

[0171] See Figure 16 The input port of the second wavelength division unit 081 is connected to the second optical fiber. One output port of the second wavelength division unit 081 is connected to the input port of the second 1×2 optical coupler 082 via optical fiber, and the other output port is connected to one input port of the second 2×1 optical coupler 084 via optical fiber. One output port of the second 1×2 optical coupler 082 is connected to another input port of the second wavelength multiplexing unit 083 via optical fiber, and the other output port is connected to the first routing module 09 via optical fiber. The other input port of the second 2×1 optical coupler 084 is connected to the second routing module 10 via optical fiber, and the output port of the second 2×1 optical coupler 084 is connected to another input port of the second wavelength multiplexing unit 083 via optical fiber. The second wavelength multiplexing unit 083 is connected to the second optical fiber.

[0172] In the event of a target communication link interruption, the second up-and-down module 08 is used for down-wave processing. The two output ports of the second wavelength division unit 081 are used to output the first wavelength signal and the second wavelength signal, respectively. Assuming the second optical fiber connected to the second wavelength division unit 081 is used to input the second wavelength multi-subcarrier signal, one output port of the second wavelength division unit 081 outputs the second wavelength multi-subcarrier signal, while the other output port does not output. The second wavelength division unit 081 outputs the second wavelength multi-subcarrier signal to the second 1×2 optical coupler 082. The second 2×1 optical coupler 084 has no input, and the second 1×2 optical coupler 082 splits the second wavelength multi-subcarrier signal into two paths, outputting them to the second multiplexing unit 083 and the first routing module 09, respectively. The first routing module 09 transmits the received signal to the receiving unit 041 in the transceiver module 04. The second multiplexing unit 083 outputs the received second wavelength multi-subcarrier signal directly. Here, by configuring the power of the two outputs of the second 1×2 optical coupler 082, the power output to the second multiplexing unit 083 is higher than the power output to the receiving unit 041. In this way, the power of the direct output signal is higher than the power of the next output signal, so that when it is transmitted to the leaf node at the end, the power of the next output signal received by the leaf node is also relatively high.

[0173] When the target communication link is uninterrupted, the second up-wave module 08 is used for up-wave. The two output ports of the second wavelength division unit 081 are used to output the first wavelength signal and the second wavelength signal, respectively. Assuming that the second optical fiber connected to the second wavelength division unit 081 is used to input the first wavelength multi-subcarrier signal, one output port of the second wavelength division unit 081 outputs the first wavelength multi-subcarrier signal, and the other output port does not output. The second wavelength division unit 081 outputs the first wavelength multi-subcarrier signal to one input port of the second 2×1 optical coupler 084, and the second 1×2 optical coupler 082 has no input. The transmitting unit 042 in the transceiver module 04 sends the generated signal to the second routing module 10, and the second routing module 10 inputs the third wavelength subcarrier signal to the up-wave input port of the second 2×1 optical coupler 084. The second 2×1 optical coupler 084 combines the third wavelength subcarrier signal with the directly input first wavelength subcarrier signal into one path and sends it to the second multiplexing unit 083. The second multiplexing unit 083 outputs the second wavelength multi-subcarrier signal. In this way, not only can the up-wave be achieved, but the subcarrier signal input by the up-wave will also not return to the receiving unit 041.

[0174] It should be noted that, in Figure 16 In the middle, the first up and down wave module 07 can be adopted Figure 15 The structure shown can also employ a 2×2 optical coupler. Furthermore, the output power of the two output ports of the second 1×2 optical coupler 082 described above is flexibly configurable, and the specific ratio is not limited in this embodiment.

[0175] Furthermore, the above descriptions of two structures for the first up-and-down wave module 07 and two structures for the second up-and-down wave module 08 are merely illustrative examples, and the embodiments of this application do not limit the structures of the first up-and-down wave module 07 and the second up-and-down wave module 08. For example, the first up-and-down wave module 07 and the second up-and-down wave module 08 can also be OADMs.

[0176] The structure of the leaf node has been described above. Based on the above structure of the central node and the leaf node, the process of point-to-multipoint (P2MP) communication between the central node and the leaf node is described below.

[0177] The following describes the process of an optical communication network changing from a fault-free state to a fault state.

[0178] In this optical communication network, Figure 2 Taking the optical communication network shown as an example, and using... Figure 6 The local node shown, and Figure 14The leaf node shown is used as an example for illustration. Assume the optical communication network starts working without faults. The central office node communicates with the leaf node using the first wavelength of light, and the third wavelength is the center wavelength of one subcarrier signal in the multi-subcarrier signal of the first wavelength. For example... Figure 17 The diagram illustrates communication between the central office node and the leaf nodes. See also... Figure 17 The central office node transmits a first-wavelength multi-subcarrier signal counterclockwise to the leaf node via the inner ring fiber, and a second-wavelength multi-subcarrier signal clockwise to the leaf node via the outer ring fiber. The first-wavelength multi-subcarrier signal and the second-wavelength multi-subcarrier signal are modulated with the same data. Figure 14 As can be seen, the leaf nodes only provide the local oscillator light for the first wavelength subcarrier. Each leaf node uses its own corresponding third wavelength local oscillator light to obtain the data modulated on its corresponding subcarrier signal within the first wavelength multi-subcarrier signal, thus achieving downlink communication. Since the leaf nodes do not provide the local oscillator light for the second wavelength subcarrier, even if a second wavelength multi-subcarrier signal is received, it will not demodulate the data modulated on that signal, and data will not be received repeatedly. Each leaf node modulates the data onto its own corresponding third wavelength subcarrier, with each leaf node corresponding to one subcarrier signal, and each subcarrier signal having a different center wavelength. Each leaf node transmits its corresponding subcarrier signal clockwise to the central office node through the outer ring fiber. All the subcarrier signals from the leaf nodes, upon reaching the central office node, form the first wavelength multi-subcarrier signal. The central office node provides the first wavelength local oscillator light and can receive the first wavelength multi-subcarrier signal, thus achieving uplink communication.

[0179] Assuming an interruption occurs between leaf node 2 and leaf node 3, after confirming a fault in the optical communication network, the communication diagram between the central office node and the leaf nodes is as follows: Figure 18 As shown. In Figure 18 In this process, the central office node does not require adjustment, the target communication link of leaf node 3 is uninterrupted and also requires no adjustment, while the target communication links of leaf nodes 1 and 2 are interrupted. Leaf nodes 1 and 2 provide local oscillator light and signal light of the fourth wavelength. Thus, the central office node sends the first wavelength multi-subcarrier signal counterclockwise to leaf node 3 through the inner ring fiber, and leaf node 3 also sends its corresponding subcarrier signal counterclockwise to the central office node through the outer ring fiber. The central office node sends the second wavelength multi-subcarrier signal clockwise to leaf nodes 1 and 2 through the outer ring fiber. Leaf nodes 1 and 2 use the fourth wavelength local oscillator light to demodulate and obtain their own data from the second wavelength multi-subcarrier signal. Leaf nodes 1 and 2 use the fourth wavelength signal light to modulate the data, obtain the fourth wavelength subcarrier, and send the fourth wavelength subcarrier signal counterclockwise to the central office node through the inner ring fiber.

[0180] exist Figure 17 and Figure 18 The curved arrows indicate the direction of downlink and uplink communication.

[0181] In this optical communication network, Figure 2 Taking the optical communication network shown as an example, and using... Figure 7 The local node shown, and Figure 13 The leaf node shown is used as an example for illustration. Assume the optical communication network starts working without faults. The central office node communicates with the leaf node using the first wavelength of light, and the third wavelength is the center wavelength of one subcarrier signal in the multi-subcarrier signal of the first wavelength. For example... Figure 19 The diagram illustrates communication between the central office node and the leaf nodes. See also... Figure 19 The first optical switch 05 and the second optical switch 06 at the central office node are opened. The central office node sends a first-wavelength multi-subcarrier signal counterclockwise to the leaf node through the inner ring fiber. Although the transceiver module 04 of the central office node also outputs a second-wavelength multi-subcarrier signal to the wavelength division multiplexing (WDM) module 02, the second-wavelength multi-subcarrier signal is not output because the WDM module 02 is connected to an optical switch that is in the open state. Figure 13 It can be seen that the leaf nodes provide the local oscillator light of the center wavelength of the first wavelength subcarrier. That is, each leaf node uses its own corresponding third wavelength local oscillator light to obtain the data modulated on its corresponding subcarrier signal in the multi-subcarrier signal of the first wavelength, thereby realizing downlink communication. From Figure 13 It can be seen that although the leaf nodes provide the local oscillator light of the center wavelength of the second-wavelength subcarrier, they do not receive data repeatedly because they do not actually receive the second-wavelength subcarrier. Each leaf node modulates the data onto its corresponding third-wavelength subcarrier, with each leaf node corresponding to one subcarrier signal, and each subcarrier signal having a different wavelength. Each leaf node transmits its corresponding subcarrier signal clockwise to the central office node through the outer ring fiber. After all the subcarrier signals corresponding to the leaf nodes reach the central office node, they form a multi-subcarrier signal of the first wavelength. The central office node provides the local oscillator light of the first wavelength and can receive the multi-subcarrier signal of the first wavelength, thus realizing uplink communication.

[0182] It is worth noting that although the leaf nodes also send the fourth wavelength subcarrier signal to the central office node, the fourth wavelength subcarrier signal corresponding to each leaf node will not enter the transceiver module 04 of the central office node because there is an open optical switch between the multiplexing module 01 and the inner ring fiber in the central office node. Therefore, the central office node will not receive data repeatedly.

[0183] Assuming an interruption occurs between leaf node 2 and leaf node 3, after confirming a fault in the optical communication network, the interaction diagram between the central office node and the leaf nodes is as follows: Figure 20 As shown. In Figure 20In this configuration, the first optical switch 05 and the second optical switch 06 at the central office node are closed. The leaf nodes remain unchanged. Thus, the central office node transmits a second-wavelength subcarrier signal clockwise to leaf nodes 1 and 2 via the outer ring fiber. Leaf nodes 1 and 2 use their corresponding fourth-wavelength local oscillator light to receive their own data from the second-wavelength subcarrier signal. Leaf nodes 1 and 2 use their corresponding fourth-wavelength signal light to modulate the data, obtaining a fourth-wavelength subcarrier, and transmit this fourth-wavelength subcarrier signal counterclockwise to the central office node via the inner ring fiber. The central office node transmits a first-wavelength multi-subcarrier signal counterclockwise to leaf node 3 via the inner ring fiber. Leaf node 3 uses its third-wavelength local oscillator light to demodulate and obtain its own data from the first-wavelength multi-subcarrier signal. Leaf node 3 uses its third-wavelength signal light to modulate the data, obtaining a third-wavelength subcarrier, and transmits this third-wavelength subcarrier signal clockwise to the central office node via the outer ring fiber.

[0184] It is worth noting that although each leaf node can still send subcarrier signals with a center wavelength of the third wavelength and a center wavelength of the fourth wavelength after a failure in the optical communication network, only the subcarrier signals with a center wavelength of the third wavelength or the subcarrier signals with a center wavelength of the fourth wavelength can reach the central office node due to the interruption between leaf node 2 and leaf node 3, thus preventing the central office node from receiving data repeatedly.

[0185] against Figures 17 to 20 It should be noted that after a failure in the optical communication network, although the first wavelength multi-subcarrier signal will not be received by leaf node 1 and leaf node 2, and the second wavelength multi-subcarrier signal will not be received by leaf node 3, in order to simplify the processing, the data of all leaf nodes will still be modulated on the first wavelength multi-subcarrier signal, and the data of all leaf nodes will still be modulated on the second wavelength multi-subcarrier signal.

[0186] For example, after a failure in an optical communication network, the central office node can also promptly report the location of the outage to the user, enabling the user to carry out repairs in a timely manner. The central office node uses the received subcarrier signals to determine the location of the outage. For example, in... Figure 2 In the optical communication network shown, the central office node can receive subcarrier signals from leaf nodes 1 and 2, but not from leaf node 3, indicating an outage between leaf nodes 2 and 3. The central office node then reports the outage location to the user's terminal, allowing for timely maintenance. Furthermore, after a network failure, the user completes maintenance at the outage location, at which point the network is no longer faulty. The central office node controls itself and the leaf nodes to operate under the condition that the network is not faulty. This facilitates control in the event of a subsequent network failure.

[0187] Based on the scheme described above, couplers are used for up-and-down processing instead of DWDM, thus simplifying the process and reducing costs. Furthermore, adding leaf nodes or enabling leaf nodes to receive more subcarrier signals in the optical communication network only requires expansion of the central office node to provide more subcarrier signals to the leaf nodes. The leaf nodes only need software configuration to ensure that the light source module 03 at the leaf node can provide more center wavelength light for the subcarriers, allowing the transceiver module 04 to receive and transmit more subcarrier signals, making implementation easy. Moreover, protection switching can be achieved using a single transceiver module 04, resulting in faster switching speeds.

[0188] In this embodiment, the explanation assumes the existence of a single fault location. When multiple fault locations exist, the solution proposed in this application may only enable some leaf nodes to resume communication, but it can also solve the problem of some nodes being unable to communicate.

[0189] The leaf nodes and local nodes described in this application embodiment can be arbitrarily combined to form an optical communication network without violating the processing logic.

[0190] In this application, the terms "first," "second," etc., are used to distinguish identical or similar items with substantially the same function and purpose. It should be understood that there is no logical or temporal dependency between "first" and "second," nor does it limit the quantity or execution order. It should also be understood that although the following description uses the terms "first," "second," etc., to describe various elements, these elements should not be limited by the terms. These terms are merely used to distinguish one element from another. For example, without departing from the scope of various examples, a first up-and-down wave module can be referred to as a second up-and-down wave module, and similarly, a second up-and-down wave module can be referred to as a first up-and-down wave module. Both the first and second up-and-down wave modules can be up-and-down wave modules, and in some cases, they can be separate and different up-and-down wave modules. In this application, the term "at least one" means one or more, and the term "multiple" means two or more.

[0191] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A central office node, characterized by The local node comprises a combining module (01), a splitting module (02), a light source module (03) and a transceiver module (04), the combining module (01) and the splitting module (02) are both used for connecting with an outer ring optical fiber and an inner ring optical fiber, the outer ring optical fiber connects the local node with a plurality of leaf nodes in series, the inner ring optical fiber connects the local node with the plurality of leaf nodes in series, and the local node is the starting point and the ending point in series; The combining module (01) is used for receiving an uplink signal and sending the uplink signal to the transceiver module (04); The light source module (03) is used for providing a local oscillator light and a signal light with the same wavelength to the transceiver module (04), and the local oscillator light comprises at least one of a first wavelength light and a second wavelength light; The transceiver module (04) is used for receiving the uplink signal sent by the combining module (01) based on the local oscillator light, generating a downlink signal based on the signal light, sending the downlink signal to the splitting module (02), and the uplink signal comprises at least one of a first wavelength uplink signal and a second wavelength uplink signal, the downlink signal comprises at least one of a first wavelength downlink signal and a second wavelength downlink signal, the first wavelength downlink signal is a multi-subcarrier signal, the second wavelength downlink signal is a multi-subcarrier signal, the first wavelength downlink signal is transmitted through the outer ring optical fiber or the inner ring optical fiber, and the transmission optical fiber of the first wavelength downlink signal is different from that of the second wavelength downlink signal, and different leaf nodes in the plurality of leaf nodes receive at least one of different subcarrier signals in the first wavelength downlink signal and different subcarrier signals in the second wavelength downlink signal; The splitting module (02) is used for sending the downlink signal received from the transceiver module (04).

2. The central node of claim 1, wherein, In the case that the optical communication network to which the local node belongs is not faulty, the combining module (01) is used for receiving the first wavelength uplink signal from the outer ring optical fiber and sending the first wavelength uplink signal to the transceiver module (04), and the splitting module (02) is used for outputting the first wavelength downlink signal to the inner ring optical fiber; or The combining module (01) is used for receiving the second wavelength uplink signal from the inner ring optical fiber and sending the second wavelength uplink signal to the transceiver module (04), and the splitting module (02) is used for outputting the second wavelength downlink signal to the outer ring optical fiber.

3. The central node of claim 1, wherein, In the case that the optical communication network to which the local node belongs is not faulty, the combining module (01) is used for receiving the first wavelength uplink signal from the outer ring optical fiber and sending the first wavelength uplink signal to the transceiver module (04), or receiving the second wavelength uplink signal from the inner ring optical fiber and sending the second wavelength uplink signal to the transceiver module (04). The wave division module (02) is configured to divide the downlink signal received from the transceiver module (04) into the downlink signal of the first wavelength and the downlink signal of the second wavelength, output the downlink signal of the first wavelength to the inner ring optical fiber, and output the downlink signal of the second wavelength to the outer ring optical fiber.

4. The central node according to any of claims 1 to 3, c h a r a c t e r i z e d b y In the case that the optical communication network to which the local node belongs fails, the local light includes the light of the first wavelength and the light of the second wavelength; The wave combination module (01) is configured to receive the uplink signal of the first wavelength from the outer ring optical fiber and receive the uplink signal of the second wavelength from the inner ring optical fiber, combine the uplink signal of the first wavelength and the uplink signal of the second wavelength into one uplink signal, and send the one uplink signal to the transceiver module (04); The wave division module (02) is configured to divide the downlink signal received from the transceiver module (04) into the downlink signal of the first wavelength and the downlink signal of the second wavelength, output the downlink signal of the first wavelength to the inner ring optical fiber, and output the downlink signal of the second wavelength to the outer ring optical fiber.

5. The central node according to any of claims 1 to 3, c h a r a c t e r i z e d b y The transceiver module (04) includes a receiving unit (041) and a transmitting unit (042); The light source module (03) is configured to provide the local light to the receiving unit (041) and provide the signal light to the transmitting unit (042); The receiving unit (041) is configured to receive the uplink signal sent by the wave combination module (01) based on the local light; The transmitting unit (042) is configured to send the downlink signal to the wave division module (02) based on the signal light.

6. The central node of claim 5, wherein, The local light includes the light of the first wavelength and the light of the second wavelength, and the light source module (03) includes a first laser (031), a second laser (032), and a combination and division unit (033); The first laser (031) and the second laser (032) are respectively connected with the combination and division unit (033); The first laser (031) is configured to output the light of the first wavelength, and the second laser (032) is configured to output the light of the second wavelength; The combination and division unit (033) is configured to combine the light of the first wavelength and the light of the second wavelength into one light, divide the one light into two lights, and send the two lights to the receiving unit (041) and the transmitting unit (042) respectively.

7. The central node of claim 5, wherein, The transceiver module (04) further includes a processing unit (043); The processing unit (043) is configured to control the light source module (03) to send the light of the first wavelength and the light of the second wavelength to the receiving unit (041) and the transmitting unit (042) in the case that the optical communication network to which the local node belongs fails, and send the light of the first wavelength or the light of the second wavelength to the receiving unit (041) and the transmitting unit (042) in the case that the optical communication network to which the local node belongs does not fail.

8. The central node of claim 3, wherein, The local node further includes a first optical switch (05) and a second optical switch (06); The first optical switch (05) is arranged between the first input port of the wavelength combining module (01) and the outer ring fiber, the second optical switch (06) is arranged between the first output port of the wavelength separating module (02) and the inner ring fiber, and the first input port and the first output port are used for transmitting the signal of the first wavelength; or, the first optical switch (05) is arranged between the second input port of the wavelength combining module (01) and the inner ring fiber, the second optical switch (06) is arranged between the second output port of the wavelength separating module (02) and the outer ring fiber, and the second input port and the second output port are used for transmitting the signal of the second wavelength. The first optical switch (05) and the second optical switch (06) are in a closed state in the case that the optical communication network to which the local node belongs is faulty, and are in an open state in the case that the optical communication network to which the local node belongs is not faulty.

9. The central node according to any of claims 1 to 3, c h a r a c t e r i z e d b y The uplink signal of the first wavelength includes subcarrier signals, and the uplink signal of the second wavelength includes subcarrier signals.

10. The central node of claim 9, wherein, The transceiver module (04) is further used for: determining whether the optical communication network to which the local node belongs is faulty based on whether the received multi-subcarrier signal carries a fault indication message; or, determining whether the optical communication network to which the local node belongs is faulty based on the number of subcarriers in the received multi-subcarrier signal.

11. A leaf node, characterized by The leaf node includes an optical source module (03), a first up-down wave module (07), a transceiver module (04), and a second up-down wave module (08); The optical source module (03) is used for providing a local oscillator light and a signal light with the same wavelength to the transceiver module (04), and the local oscillator light at least includes light of a third wavelength; The first up-down wave module (07) is used for receiving a first downlink signal from a first optical fiber, dividing the first downlink signal into two downlink signals, and respectively sending the two downlink signals to the transceiver module (04) and the first optical fiber; The transceiver module (04) is used for acquiring a downlink signal of the third wavelength from the received downlink signal based on the local oscillator light, and generating an uplink signal of the third wavelength based on the signal light, and sending the generated signal to the second up-down wave module (08), wherein the first downlink signal is a multi-subcarrier signal of a first wavelength or a multi-subcarrier signal of a second wavelength sent by a local node connected to the first optical fiber, the downlink signal of the third wavelength is part of the multi-subcarrier signal, the multi-subcarrier signal of the first wavelength is transmitted through an outer ring fiber or an inner ring fiber, and the transmission optical fiber of the multi-subcarrier signal of the first wavelength is different from that of the multi-subcarrier signal of the second wavelength. The second up-and-down wave module (08) is configured to output, to the second optical fiber, the uplink signal received from the second optical fiber after being combined with the uplink signal of the third wavelength, the first optical fiber being an outer ring optical fiber, and the second optical fiber being an inner ring optical fiber; or the first optical fiber being an inner ring optical fiber, and the second optical fiber being an outer ring optical fiber, the outer ring optical fiber being connected in series with the local node and the leaf node, and the inner ring optical fiber being connected in series with the local node and the leaf node, the local node being the starting point and the end point when being connected in series.

12. The leaf node of claim 11, wherein, In the case that the target communication link of the leaf node is interrupted, the local light source at least includes light of a fourth wavelength, and the leaf node further includes a first routing module (09) and a second routing module (10); The second up-and-down wave module (08) is configured to receive a second downlink signal from the second optical fiber, divide the second downlink signal into two downlink signals, and send the two downlink signals to the first routing module (09) and the second optical fiber, respectively. The first routing module (09) is configured to send the downlink signal received from the second up-and-down wave module (08) to the transceiver module (04). The transceiver module (04) is configured to obtain the downlink signal of the fourth wavelength from the received downlink signal based on the local light source, and generate the uplink signal of the fourth wavelength based on the signal light, and send the generated signal to the second routing module (10). The second routing module (10) is configured to send the uplink signal of the fourth wavelength in the received signal to the first up-and-down wave module (07). The first up-and-down wave module (07) is configured to output, to the first optical fiber, the uplink signal received from the first optical fiber after being combined with the uplink signal of the fourth wavelength.

13. The leaf node of claim 12, wherein, In the case that the target communication link of the leaf node is not interrupted, the first up-and-down wave module (07) is configured to receive a first downlink signal from the first optical fiber, divide the first downlink signal into two downlink signals, and send the two downlink signals to the first routing module (09) and the first optical fiber, respectively. The first routing module (09) is configured to send the downlink signal received from the first up-and-down wave module (07) to the transceiver module (04). The transceiver module (04) is configured to generate the uplink signal of the third wavelength based on the signal light, and send the generated signal to the second routing module (10). The second routing module (10) is configured to send the uplink signal of the third wavelength in the received signal to the second up-and-down wave module (08).

14. The leaf node according to claim 12 or 13, c h a r a c t e r i z e d b y The transceiver module (04) includes a receiving unit (041) and a transmitting unit (042); The light source module (03) is configured to provide the local light to the receiving unit (041), and provide the signal light to the transmitting unit (042); The receiving unit (041) is configured to receive the uplink signal based on the local light. The transmitting unit (042) is configured to transmit the downlink signal based on the signal light.

15. The leaf node of claim 14, wherein, The local light includes light of the third wavelength and light of the fourth wavelength, and the light source module (03) includes a first laser (031), a second laser (032), and a combining and splitting unit (033); The first laser (031) and the second laser (032) are connected with the combining and splitting unit (033) respectively; The first laser (031) is configured to output light of the third wavelength, and the second laser (032) is configured to output light of the fourth wavelength. The combining and splitting unit (033) is configured to combine the light of the third wavelength and the light of the fourth wavelength into one light, split the one light into two lights, and send the two lights to the receiving unit (041) and the transmitting unit (042) respectively.

16. The leaf node of claim 14, wherein, The light source module (03) includes a first laser (031), a second laser (032), a switching unit (034), and a splitting unit (035); The switching unit (034) is connected with the splitting unit (035); The first laser (031) is configured to output light of the third wavelength, and the second laser (032) is configured to output light of the fourth wavelength. The switching unit (034) is configured to be connected with the first laser (031) when the target communication link is not interrupted, and be connected with the second laser (032) when the target communication link is interrupted. The splitting unit (035) is configured to split the received light into two lights and send the two lights to the receiving unit (041) and the transmitting unit (042) respectively.

17. The leaf node of claim 12 or 13, wherein, The first up and down wave module (07) and the second up and down wave module (08) are both 2×2 optical couplers.

18. The leaf node of claim 12 or 13, wherein, The first up and down wave module (07) includes a first splitting unit (071), a first 1×2 optical coupler (072), a first combining unit (073), and a first 2×1 optical coupler (074); When the target communication link is not interrupted, the first splitting unit (071) is configured to receive the first downlink signal from the first optical fiber and send the first downlink signal to the first 1×2 optical coupler (072); the first 1×2 optical coupler (072) is configured to split the first downlink signal into two downlink signals and send the two downlink signals to the first combining unit (073) and the first routing module (09) respectively; and the first combining unit (073) is configured to output the received downlink signal to the first optical fiber. When the target communication link is interrupted, the first splitting unit (071) is configured to receive the uplink signal from the first optical fiber and send the received uplink signal to the first 2×1 optical coupler (074); the first 2×1 optical coupler (074) is configured to receive the fourth wavelength uplink signal sent by the second routing module (10), combine the received two uplink signals into one uplink signal, and send the one uplink signal to the first combining unit (073); and the first combining unit (073) is configured to output the received uplink signal to the first optical fiber.

19. The leaf node of claim 12 or 13, wherein, The second up-down module (08) comprises a second splitting unit (081), a second 1*2 optical coupler (082), a second combining unit (083) and a second 2*1 optical coupler (084); In the case that the target communication link is not interrupted, the second splitting unit (081) receives the uplink signal from the second optical fiber and sends the received uplink signal to the second 2*1 optical coupler (084); the second 2*1 optical coupler (084) receives the uplink signal of the third wavelength sent by the second routing module (10), combines the received two uplink signals into one uplink signal and sends the uplink signal to the second combining unit (083); the second combining unit (083) outputs the received uplink signal to the first optical fiber; In the case that the target communication link is interrupted, the second splitting unit (081) receives the second downlink signal from the second optical fiber and sends the second downlink signal to the second 1*2 optical coupler (082); the second 1*2 optical coupler (082) divides the second downlink signal into two downlink signals and sends the two downlink signals to the second combining unit (083) and the first routing module (09) respectively; the second combining unit (083) outputs the received downlink signal to the second optical fiber.

20. The leaf node of claim 17, wherein, The first port of the first routing module (09) is used for filtering the signal input through the first up-down module (07), and the first port is the port connected to the first up-down module (07); The second port of the first routing module (09) is used for filtering the signal input through the second up-down module (08), and the second port is the port connected to the second up-down module (08).

21. The leaf node of claim 12 or 13, wherein, The uplink signal of the third wavelength is a subcarrier signal, and the uplink signal of the fourth wavelength and the downlink signal of the fourth wavelength are both subcarrier signals.

22. An optical communications network, comprising: The optical communication network comprises a local node, a plurality of leaf nodes, an outer ring optical fiber and an inner ring optical fiber; The local node and the plurality of leaf nodes are connected in series through the outer ring optical fiber, and the local node and the plurality of leaf nodes are connected in series through the inner ring optical fiber, and the local node is the starting point and the end point when being connected in series; The local node is the local node of any one of claims 1 to 10, and the leaf node is the leaf node of any one of claims 11 to 21.

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