CN113644968B

CN113644968B - Submarine optical transmission system and disaster recovery method thereof

Info

Publication number: CN113644968B
Application number: CN202111189499.1A
Authority: CN
Inventors: 房永祥; 樊晓燕; 苏丹; 许昌武
Original assignee: Huahai Communication Technology Co Ltd
Current assignee: Huahai Communication Technology Co Ltd
Priority date: 2021-10-13
Filing date: 2021-10-13
Publication date: 2021-12-21
Anticipated expiration: 2041-10-13
Also published as: CN113644968A

Abstract

The application provides a submarine optical transmission system and a disaster recovery method thereof. The system comprises a first land station and a second land station which are connected through a first main road and a second main road; the system comprises at least one light splitting unit arranged on a trunk line, wherein each light splitting unit corresponds to an underwater main node, and the light splitting units are connected with the corresponding underwater main nodes through a first downlink branch optical fiber, a second downlink branch optical fiber, a first uplink branch optical fiber and a second uplink branch optical fiber. In the uplink service, an uplink optical signal of the underwater main node can be bidirectionally transmitted to the first and second shore stations, and in the downlink service, the first and second shore stations can transmit downlink optical signals from two directions. Therefore, even if the uplink optical signal is in a transmission fault in a certain direction, the first shore station or the second shore station can receive the uplink optical signal from the other direction, and even if the downlink optical signal is in a transmission fault in a certain direction, the underwater main node can receive the downlink optical signal from the other direction, so that the disaster tolerance capability of the service is realized.

Description

Submarine optical transmission system and disaster recovery method thereof

Technical Field

The present application relates to the field of optical communication technologies, and in particular, to a submarine optical transmission system and a disaster recovery method thereof.

Background

The seabed observation network is a novel platform for human to observe the ocean, can realize all-weather, in-situ, long-term, continuous, real-time, high-resolution and high-precision observation of the ocean from the seabed to the sea surface, and plays an important supporting role in the scientific development of the ocean. Through the submarine observation network, scientific research personnel can monitor deep sea experiments in real time on the shore, remotely monitor various emergencies such as submarine storm surge, volcanic eruption, earthquake, tsunami, landslide and red tide, and better serve national defense construction, scientific research and national economy construction. In addition, abundant resources such as petroleum and natural gas, hydrothermal sulfides, mineral nodules, deep sea organisms and the like are also stored in the ocean, the ocean can be reasonably observed and researched through the submarine observation network, and the submarine resources can be fully developed and effectively protected.

In order to realize long-term, in-situ and real-time observation of the seabed, a large amount of equipment of a seabed observation network is arranged on the seabed for a long time, and the problems of long transmission distance, difficult power supply, difficult mass data transmission and the like are faced. To solve these problems, the current submarine observation network is usually implemented by using optical communication technology, that is, using a composite optical-electrical cable to extend power and communication from land to the submarine observation equipment, and the communication between the onshore equipment and the submarine equipment is performed by optical signals.

Fig. 1 is a schematic structural diagram of a current submarine observation network. As shown in fig. 1, the seafloor observatory network may include two onshore stations (hereinafter referred to as "shore stations") disposed on shore and at least one Primary Node (PN) disposed on the seafloor (fig. 1 illustrates two subsea primary nodes). For convenience of description, the two shore stations will be referred to herein as shore a and shore B, and the two subsea master nodes will be referred to as a first master node PN-1 and a second master node PN-2. Each underwater main node is connected to the shore a and the shore B via an optical fiber pair and an optical splitter (BU), for example, the first main node PN-1 is connected to the shore a and the shore B via an optical fiber pair 1 and a first optical splitter BU-1, and the second main node PN-2 is connected to the shore a and the shore B via an optical fiber pair 2 and a second optical splitter BU-2. Wherein one optical fiber of the pair is used for transmitting optical signals in one direction, for example, in the pair 1, one optical fiber is used for transmitting optical signals in the direction of the shore a → the first master node PN-1 → the shore B, and the other optical fiber is used for transmitting optical signals in the direction of the shore B → the first master node PN-1 → the shore a.

Although the submarine observation network shown in fig. 1 realizes transmission of optical signals between a shore station and a main underwater node, there are some problems in practical applications, such as:

(1) each underwater main node and the shore station have an exclusive optical fiber pair, so that one optical fiber pair can only realize the communication between one underwater main node and the shore station, and the utilization rate of the optical bandwidth is low, so that the optical fiber pair is not suitable for a communication/observation hybrid network or an oil-gas/observation hybrid network with certain requirements on the communication bandwidth;

(2) when the submarine optical fiber is used for long-distance communication, the submarine Repeater is required to amplify and reinforce optical signals, however, the number of optical fiber pairs which can be accessed by the submarine Repeater is limited, so that the number of the underwater main nodes which can be expanded by the submarine observation network shown in fig. 1 is limited by the number of the optical fiber pairs which can be accessed by the submarine Repeater, and the expansion capability is poor.

(3) Although bidirectional communication is realized between the underwater main node and the shore station A and the shore station B, the submarine observation network has no disaster tolerance capability, for example, when one of the optical fibers in the optical fiber pair is disconnected, the communication in one direction is interrupted.

In order to solve the above problems, some current submarine observation networks adopt a scheme combining Wavelength Division Multiplexing (WDM) and optical add-drop multiplexer (OADM) technologies, which may be referred to as a no frequency reuse "OADM scheme. In the scheme, all underwater main nodes share one optical fiber pair, multiple beams of laser with different wavelengths can be simultaneously sent on a single optical fiber, the laser with each wavelength corresponds to one channel, multiple channels can be formed by the lasers with different beams, and each underwater main node only occupies a plurality of channels.

Fig. 2 is a schematic structural diagram of an ocean bottom observation network adopting a "no frequency reuse" OADM scheme according to an embodiment of the present application. As shown in fig. 2, on the trunk fiber between the shore a and the shore B, the optical signal has only one transmission direction, namely: the transmission is carried out from the shore station A to the shore station B, the light splitting unit on the trunk line optical fiber adopts an optical fiber light splitting type light splitting unit, and wavelength channels distributed from the shore station to the underwater main node are lambda 1 and lambda 2. After trunk optical signals (lambda 1 and lambda 2) from a shore station A enter a first optical splitter BU-1, the first optical splitter BU-1 splits a certain proportion of downlink optical signals (lambda 1 and lambda 2) and transmits the downlink optical signals to a first main node PN-1; an uplink optical signal of the first main node PN-1 is located in a wavelength channel and is lambda 3, the uplink optical signal is sent to a first optical splitter BU-1 by the first main node PN-1, the first optical splitter BU-1 combines the uplink optical signal (lambda 3) of the first main node PN-1 into main-path optical signals (lambda 1 and lambda 2), power superposition is usually performed to form main-path optical signals (lambda 1, lambda 2 and lambda 3), and the main-path optical signals (lambda 1, lambda 2 and lambda 3) continue to be transmitted to a direction B of the shore station; after the trunk optical signals (lambda 1, lambda 2 and lambda 3) enter the second optical splitter BU-2, the second optical splitter BU-2 separates downlink optical signals (lambda 1, lambda 2 and lambda 3) in a certain proportion and transmits the downlink optical signals to the second main node PN-2; the uplink optical signal of the second main node PN-2 is located in a wavelength channel with the wavelength channel of lambda 4, the second main node PN-2 sends the uplink optical signal to the second optical splitter BU-2, and the second optical splitter BU-2 combines the uplink optical signal (lambda 4) of the second main node PN-2 into the main-path optical signals (lambda 1, lambda 2 and lambda 3) to form main-path optical signals (lambda 1, lambda 2, lambda 3 and lambda 4) and continues to transmit towards the direction of the shore station B.

Although the undersea observation network shown in fig. 2 improves the utilization rate of optical bandwidth by WDM and OADM technologies, there still exist some problems in practical applications, such as:

(1) there is no Dummy Light (DL) signal in the optical fiber, so when designing an optical communication network, the service cannot be flexibly adjusted, and the nonlinear cost is large.

(2) The traffic signal has no bidirectional 1+1 protection mechanism. The 1+1 protection mechanism is a mode for protecting service flow, and means that a sending end of a signal sends the same signal on a main channel and a standby channel, a receiving end selects and receives the signal on the main channel under normal conditions, and when the main channel is damaged, the main service is recovered by switching and selectively receiving the signal in the standby channel.

(3) The service signal is transmitted in a single direction, namely: only from the underwater main node to the shore a or only from the underwater main node to the shore B.

(4) Because the existing submarine repeater RPT equipment generally works in an optical power locking mode, under the condition of no DL signal, after an uplink optical signal in an underwater main node is added into a trunk optical fiber, the influence on the service quality of other nodes is large, and in serious cases, the service cannot be transmitted.

Therefore, the current submarine observation network scheme cannot have disaster recovery capability, good expansibility and poor reliability under the conditions of high bandwidth, bidirectional communication capability and 1+1 service protection capability.

Disclosure of Invention

The embodiment of the application provides a submarine optical transmission system and a disaster recovery method thereof, the submarine optical transmission system can be used as a submarine observation network, can realize bidirectional 1+1 protection of service signals of the submarine observation network system, can realize service protection and disaster recovery processes when trunk optical fibers or branch optical fibers of the submarine observation network system have faults, and improves the reliability of the submarine observation network.

In a first aspect, an embodiment of the present application provides an undersea optical transmission system, including: the first trunk optical fiber is used for transmitting optical signals from the first shore station to the second shore station, and the second trunk optical fiber is used for transmitting optical signals from the second shore station to the first shore station; each light splitting unit is correspondingly provided with an underwater main node and is connected with the underwater main node through a first downlink branch optical fiber, a second downlink branch optical fiber, a first uplink branch optical fiber and a second uplink branch optical fiber; the light splitting unit includes: the first optical switch, the second optical switch, the third optical switch, the fifth optical switch and the sixth optical switch are connected in series; the first optical switch is arranged between the first optical splitter and the first downlink branch optical fiber and used for controlling the on-off of the downlink optical signal in the first downlink branch optical fiber; the second optical switch is arranged between the second optical splitter and the first uplink branch optical fiber and used for controlling the on-off of the uplink optical signal in the first uplink branch optical fiber; the third optical switch is arranged between the third optical splitter and the second downlink branch optical fiber and is used for controlling the on-off of the downlink optical signal in the second downlink branch optical fiber; the first optical switch and the third optical switch are used for enabling the underwater main node to select one of the first trunk optical fiber and the second trunk optical fiber to receive a downlink optical signal through on-off control; the fourth optical switch is arranged between the fourth optical splitter and the second uplink branch optical fiber and used for controlling the on-off of the uplink optical signal in the second uplink branch optical fiber; the fifth optical switch and the sixth optical switch are arranged in series and are used for forming an optical path between the first optical splitter and the second optical splitter and an optical path between the third optical splitter and the fourth optical splitter; according to the requirement, the fifth optical switch can be further configured to send the optical signal in the first trunk optical fiber to the fourth optical splitter when the optical signal in the first trunk optical fiber passes through the first optical splitter, so as to implement optical signal loopback from the first trunk optical fiber to the second trunk optical fiber; according to the requirement, the sixth optical switch can be further configured to switch and send the optical signal in the second trunk optical fiber to the second optical splitter when the optical signal in the second trunk optical fiber passes through the third optical splitter, so as to implement optical signal loopback from the second trunk optical fiber to the first trunk optical fiber; the underwater main node comprises a first wave combiner, a second wave combiner, an optical amplifier, two photoelectric modules, a filter and any one of light splitters; the input end of the first wave combiner is connected with the first downlink branch optical fiber and the second downlink branch optical fiber and used for sending downlink optical signals in the first downlink branch optical fiber or the second downlink branch optical fiber to the optical amplifier; the optical amplifier is used for amplifying the received optical signal and then sending the amplified optical signal to the filter or the optical splitter; when the underwater main node comprises a filter, the filter is used for filtering the received optical signals to obtain optical signals with two wavelengths and sending the optical signals to the two photoelectric modules, and each photoelectric module receives the optical signal with one of the two wavelengths; when the underwater main node comprises the optical splitter, the optical splitter is used for splitting the received optical signals into two parts and sending the two parts to the two photoelectric modules, and each photoelectric module receives one part of the optical signals; the two photoelectric modules are used for receiving optical signals from the filter or the optical splitter and sending the received optical signals to the secondary node or the junction box device in the form of optical signals or electric signals; the two photoelectric modules are also used for receiving electric signals or optical signals from the secondary node or the junction box device, and sending the received electric signals or optical signals to the second wave combiner in the form of optical signals with two wavelengths; the second combiner is used for converging optical signals from the two photoelectric modules to obtain an uplink optical signal containing two wavelengths, and the uplink optical signal is sent to the first uplink branch optical fiber and the second uplink branch optical fiber, so that the uplink optical signal is received by the first shore station and the second shore station in a two-way mode.

According to the technical scheme provided by the embodiment of the application, in the uplink service, the uplink optical signal of the underwater main node can be transmitted to the first shore station and the second shore station in a two-way mode through the light splitting unit, so that even if the uplink optical signal has a transmission fault in one direction, the first shore station or the second shore station can receive the uplink optical signal from the other direction, and the disaster tolerance capability of the uplink service is realized; in the downlink service, the first shore station and the second shore station send downlink optical signals to the underwater main node from two directions, and the underwater main node selects the downlink optical signals in one direction to receive through the light splitting unit, so that even if the downlink optical signals have transmission faults in one direction, the underwater main node can also receive the downlink optical signals from the other direction, the 1+1 protection in two directions is realized, and the submarine optical transmission system has the disaster tolerance capability of the uplink service.

In one implementation, the two optoelectronic modules are specifically configured to receive an optical signal from a filter or an optical splitter, perform photoelectric conversion on the received optical signal, obtain a corresponding electrical signal, and send the electrical signal to a secondary node or a junction box device; the two photoelectric modules are further specifically used for receiving electrical signals from the secondary node or the junction box device, performing electro-optical conversion on the received electrical signals, obtaining optical signals with two wavelengths, and sending the optical signals to the second combiner.

In one implementation, the two optoelectronic modules are specifically configured to receive an optical signal from a filter or an optical splitter, perform photoelectric conversion and electro-optical conversion on the received optical signal, and send the obtained optical signal to a secondary node or a junction box device; the two photoelectric modules are further specifically used for receiving optical signals from the secondary node or the junction box device, performing photoelectric conversion and electro-optical conversion on the received optical signals, obtaining optical signals with two wavelengths, and sending the optical signals to the second combiner.

In one implementation, an undersea optical transmission system transmits optical signals over a plurality of wavelength division multiplexed WDM channels, wherein a portion of the WDM channels are used to transmit uplink optical signals and downlink optical signals, the uplink optical signals and the downlink optical signals occupy different WDM channels, and the remaining WDM channels are used to transmit dummy optical DL signals.

In one implementation mode, downlink optical signals sent by the first and second shore stations to each underwater main node occupy two WDM channels, and the WDM channels corresponding to different underwater main nodes are different.

In one implementation, the first and second shore stations transmit downlink optical signals to respective underwater host nodes in a time division multiplexed or segment distributed manner over two WDM channels.

In one implementation, the uplink optical signals sent by each underwater master node to the first and second shore stations occupy two WDM channels, and the WDM channels occupied by the uplink optical signals sent by different underwater master nodes are different.

In one implementation mode, when a trunk optical fiber cable breaking fault occurs between a second shore station and an adjacent light splitting unit, the first shore station is used for sending monitoring signals to each light splitting unit; and the light splitting unit adjacent to the second shore station is used for looping the optical signal in the first trunk optical fiber back to the second trunk optical fiber according to the monitoring signal, and the rest light splitting units are used for cutting off any one road uplink optical signal of the corresponding underwater main node according to the monitoring signal.

In one implementation mode, when a trunk optical fiber cable breaking fault occurs between a first shore station and an adjacent light splitting unit, a second shore station is used for sending monitoring signals to each light splitting unit; the light splitting unit adjacent to the first shore station is used for returning an optical signal in the second trunk optical fiber to the first trunk optical fiber according to the monitoring signal; and the other light splitting units are used for cutting off any one road uplink optical signal of the corresponding underwater main node according to the monitoring signal.

In one implementation mode, when a branch optical fiber cable breaking fault occurs between any underwater main node and the light splitting unit, the first shore station or the second shore station is used for sending a monitoring signal to the light splitting unit on the fault branch optical fiber; the light splitting unit on the fault branch optical fiber is used for cutting off two paths of uplink optical signals of the underwater main node on the fault branch optical fiber according to the monitoring signal; the first and second shore stations are used for supplementing WDM channels occupied by uplink optical signals of the underwater main node on the fault branch optical fiber with false optical signals.

In one implementation mode, when any underwater main node fails, the first shore station or the second shore station is used for sending a monitoring signal to the light splitting unit corresponding to the failed underwater main node; the light splitting unit corresponding to the underwater main node with the fault is used for cutting off two paths of uplink optical signals of the underwater main node with the fault according to the monitoring signal; the first and second land stations are used for supplementing WDM channels occupied by uplink optical signals of the failed underwater main node with false optical signals.

In a second aspect, an embodiment of the present application provides a disaster recovery method, which is applicable to the undersea optical transmission system provided in the first aspect and any implementation manner thereof. The method comprises the following steps: when the first shore station detects that a trunk optical fiber cable breaking fault occurs between the second shore station and the adjacent light splitting units, the first shore station sends monitoring signals to the light splitting units; and the light splitting unit adjacent to the second shore station loops the light signal in the first trunk optical fiber back to the second trunk optical fiber according to the monitoring signal, and the rest light splitting units cut off any one road uplink light signal of the corresponding underwater main node according to the monitoring signal. The technical scheme provided by the embodiment of the application can be applied to the submarine observation network system with higher uplink and downlink service capacity and higher bandwidth requirement, can realize the service protection and disaster recovery process when the trunk optical fiber of the submarine observation network system fails, and improves the reliability of the submarine observation network.

In a third aspect, an embodiment of the present application provides a disaster recovery method, which is applicable to the undersea optical transmission system provided in the first aspect and any implementation manner thereof. The method comprises the following steps: when a first shore station or a second shore station detects that a branch optical fiber cable breaking fault occurs between any one underwater main node and the light splitting unit, a monitoring signal is sent to the light splitting unit on the fault branch optical fiber; the light splitting unit on the fault branch optical fiber cuts off two paths of uplink optical signals of the underwater main node on the fault branch optical fiber according to the monitoring signal; the first and second shore stations supplement WDM channels occupied by the uplink optical signals of the underwater main node on the fault branch optical fiber with false optical signals. The technical scheme provided by the embodiment of the application can be applied to the submarine observation network system with higher uplink and downlink service capacity and higher bandwidth requirement, can realize the service protection and disaster recovery process when the branch optical fiber of the submarine observation network system fails, and improves the reliability of the submarine observation network.

In a fourth aspect, an embodiment of the present application provides a disaster recovery method, which is applicable to the undersea optical transmission system provided in the first aspect and any implementation manner thereof. The method comprises the following steps: when the first shore station or the second shore station detects that any one underwater main node fails, a monitoring signal is sent to a light splitting unit corresponding to the failed underwater main node; the light splitting unit corresponding to the underwater main node with the fault cuts off two paths of uplink optical signals of the underwater main node with the fault according to the monitoring signal; the WDM channels occupied by the upstream optical signals of the underwater main node with the fault are supplemented by the false optical signals by the first and second shore stations. The technical scheme provided by the embodiment of the application can be applied to the submarine observation network system with higher uplink and downlink service capacity and higher bandwidth requirement, can realize the service protection and disaster recovery process when the branch optical fiber of the submarine observation network system fails, and improves the reliability of the submarine observation network.

Drawings

FIG. 1 is a schematic diagram of a current submarine observation network;

FIG. 2 is a schematic diagram of an architecture of a subsea observation network employing an OADM approach, as shown in an embodiment of the present application;

fig. 3 is a schematic structural diagram of an undersea optical transmission system provided in an embodiment of the present application;

FIG. 4 is a schematic structural diagram of a light splitting unit provided in an embodiment of the present application;

fig. 5 is a schematic structural diagram of an underwater main node provided in an embodiment of the present application;

FIG. 6 is a schematic connection diagram of a light splitting unit and an underwater main node provided in an embodiment of the present application;

FIG. 7 is a schematic structural diagram of another underwater main node provided in an embodiment of the present application

Fig. 8 is a flowchart of an upstream service implemented by the undersea optical transmission system according to the embodiment of the present application;

fig. 9 is a flowchart of a submarine optical transmission system implementing a downlink service according to an embodiment of the present application;

fig. 10 is a schematic WDM wavelength channel allocation diagram of an undersea optical transmission system according to an embodiment of the present application;

fig. 11 is a schematic signal transmission diagram of an embodiment of the present application illustrating an undersea optical transmission system without failure;

fig. 12a, 12b, and 12c are flowcharts illustrating a trunk disaster recovery of the undersea optical transmission system according to an embodiment of the present application;

fig. 13a, 13b, and 13c are flowcharts illustrating a branch disaster recovery of an undersea optical transmission system according to an embodiment of the present application;

fig. 14 is a WDM wavelength channel allocation schematic diagram of an undersea optical transmission system of a multiplexing scheme shown in an embodiment of the present application;

fig. 15 is a schematic diagram of signal transmission when the submarine optical transmission system of the multiplexing scheme shown in the embodiment of the present application is not in failure;

fig. 16a, 16b, and 16c are flowcharts of trunk disaster recovery of the undersea optical transmission system according to the multiplexing scheme shown in the embodiment of the present application;

fig. 17a, 17b, and 17c are flowcharts of branch disaster recovery of the undersea optical transmission system in the multiplexing scheme according to the embodiment of the present application.

Detailed Description

The embodiment of the application provides a submarine optical transmission system which can be used as a submarine observation network, and the submarine observation network has disaster recovery capability and good expansibility under the conditions of high bandwidth, bidirectional communication capability and 1+1 service protection capability, so that the reliability of the submarine observation network is improved.

Fig. 3 is a schematic structural diagram of an undersea optical transmission system provided in an embodiment of the present application.

As shown in fig. 3, the undersea optical transmission system includes: a first shore station 100 and a second shore station 200, the first shore station 100 and the second shore station 200 being connected by trunk optical fibers; at least one light splitting unit 300 disposed on the trunk optical fiber, and when the number of the light splitting units 300 is plural, the plural light splitting units 300 are disposed in series between the first and

second shore stations

100 and 200. Each light splitting unit 300 is correspondingly provided with an underwater main node 400, and the light splitting unit 300 is connected with the corresponding underwater main node 400 through a branch optical fiber. Each subsea master node 400 may also be connected to at least one secondary node 500 or a docking box 501.

In a specific implementation, the trunk fiber between the first and

second shore stations

100 and 200 may include a first trunk fiber F1 and a second trunk fiber F2, where the first trunk fiber F1 is used for transmitting optical signals from the first shore station 100 to the second shore station 200, and the second trunk fiber F2 is used for transmitting optical signals from the second shore station 200 to the first shore station 100.

In a specific implementation, the branch optical fibers between each light splitting unit 300 and the underwater main node 400 may include a first downlink branch optical fiber DR1, a second downlink branch optical fiber DR2, a first uplink branch optical fiber AD1, and a second uplink branch optical fiber AD 2. The first downlink branch optical fiber DR1 is connected with the first trunk optical fiber F1 through the light splitting unit 300, the second downlink branch optical fiber DR2 is connected with the second trunk optical fiber F2 through the light splitting unit 300, the first uplink branch optical fiber AD1 is connected with the first trunk optical fiber F1 through the light splitting unit 300, and the second uplink branch optical fiber AD2 is connected with the second trunk optical fiber F2 through the light splitting unit 300.

In this embodiment, the first and

second shore stations

100 and 200 are both overwater shore stations, and the first and

second shore stations

100 and 200 are mainly configured to receive a service signal sent by the underwater master node 400, send the service signal to a network management device for analysis, or form a transmission network with other devices to continuously transmit the underwater service signal. In addition, the first and

second shore stations

100 and 200 also have a function of managing underwater equipment, such as a light splitting unit 300 that transmits a control command to underwater, an underwater master node 400, and the like.

In the embodiment of the present application, depending on the number of the underwater master nodes 400, one or more light splitting units 300 may be disposed on the trunk optical fiber between the first and

second shore stations

100 and 200, and for reasons of space, only two light splitting units 300 are exemplarily shown in fig. 3. Accordingly, two subsea host nodes 400 are shown in fig. 3, by way of example only, at the same time.

Wherein, the effect of the underwater main node 400 includes: (1) converging uplink service signals of secondary nodes, such as Gigabit Ethernet (GE) signals and Synchronous Digital Hierarchy (SDH) signals, wherein the number of the secondary nodes supported by the underwater main node is related to the communication capacity of the underwater main node and the power consumption of the secondary nodes; (2) distributing the downlink management information of the shore station to each secondary node through the service type supported by the secondary node; (3) and respectively sending the converged service signals to two directions on the trunk optical fiber.

The optical splitting unit 300 is configured to implement optical signal distribution between the trunk optical fiber and the branch optical fiber in a normal transmission scenario (i.e., in a scenario where an underwater node fault, a cable break, and the like do not occur in the undersea optical transmission system), for example: and separating the downlink optical signals and transmitting the separated downlink optical signals to an underwater main node, and combining the uplink optical signals into the trunk optical fiber. In addition, the light splitting unit 300 is also used for completing switching actions when the submarine optical transmission system has an underwater node fault, a cable break and other scenes, so as to realize disaster recovery of trunk optical fibers and branch optical fibers. The specific manner in which the light splitting unit 300 performs the switching action to implement the trunk fiber and branch disaster tolerance will be further described in the following.

In addition, as further shown in fig. 3, since the submarine observation network is laid on the seabed in a wide range, the optical transmission distance in the optical cable is long, and thus, the optical signal may have significant intensity attenuation during transmission. In order to overcome such attenuation, in the undersea optical transmission system provided in the embodiment of the present application, at least one repeater 600 may be further disposed between adjacent shore stations and the optical splitting unit, and between two adjacent optical splitting units, where the repeater 600 is configured to amplify an optical signal to implement long-distance transmission of the optical signal. The specific number of repeaters 600 may be determined according to the span length of the optical cable, and is not specifically limited in the embodiment of the present application. In general, the longer the span length, the greater the number of repeaters 600 can be; the shorter the span length, the fewer the number of repeaters 600, or no repeaters 600 may be provided.

Fig. 4 is a schematic structural diagram of a light splitting unit provided in an embodiment of the present application.

Fig. 5 is a schematic structural diagram of an underwater main node provided in an embodiment of the present application.

Fig. 6 is a schematic connection diagram of a light splitting unit and an underwater main node provided in an embodiment of the present application.

As shown in fig. 4 and 6, in one implementation, the light splitting unit 300 includes a first light splitter C1, a second light splitter C2, a third light splitter C3, a fourth light splitter C4, a first optical switch K1, a second optical switch K2, a third optical switch K3, a fourth optical switch K4, a fifth optical switch K5, a sixth optical switch K6; the first optical splitter C1 is disposed on the light incoming side F1I of the first trunk optical fiber F1, and is configured to split a downlink optical signal from the first trunk optical fiber F1, and send the downlink optical signal split from the first trunk optical fiber F1 to the sub-master node through the first downlink branch optical fiber DR1, and the first optical switch K1 is disposed between the first optical splitter C1 and the first downlink branch optical fiber DR1, and is configured to control on/off of the downlink optical signal in the first downlink branch optical fiber DR 1; the second optical splitter C2 is disposed on the light exit side F1O of the first trunk optical fiber F1, and is configured to receive an uplink optical signal of the underwater main node through the first uplink branch optical fiber AD1, and combine the uplink optical signal in the first uplink branch optical fiber AD1 into the first trunk optical fiber F1, and the second optical switch K2 is disposed between the second optical splitter C2 and the first uplink branch optical fiber AD1, and is configured to control on/off of the uplink optical signal in the first uplink branch optical fiber AD 1; the third optical splitter C3 is disposed on the light incoming side F2I of the second trunk optical fiber F2, and is configured to split a downlink optical signal from the second trunk optical fiber F2, and send the downlink optical signal split from the second trunk optical fiber F2 to the sub-master node through the second downlink branch optical fiber DR2, and the third optical switch K3 is disposed between the third optical splitter C3 and the second downlink branch optical fiber DR2, and is configured to control on/off of the downlink optical signal in the second downlink branch optical fiber DR 2; the first optical switch K1 and the third optical switch K3 are used for enabling the underwater main node to select from the first trunk optical fiber F1 and the second trunk optical fiber F2 to receive downlink optical signals through on-off control; the fourth optical splitter C4 is disposed on the light exit side F2O of the second trunk optical fiber F2, and is configured to receive an uplink optical signal of the underwater main node through the second uplink branch optical fiber AD2, and combine the uplink optical signal in the second uplink branch optical fiber AD2 into the second trunk optical fiber F2, and the fourth optical switch K4 is disposed between the fourth optical splitter C4 and the second uplink branch optical fiber AD2, and is configured to control on/off of the uplink optical signal in the second uplink branch optical fiber AD 2; the fifth optical switch K5 and the sixth optical switch K6 are arranged in series to form an optical path between the first optical splitter C1 and the second optical splitter C2 and an optical path between the third optical splitter C3 and the fourth optical splitter C4; according to the requirement, the fifth optical switch K5 may be further configured to send the optical signal in the first trunk fiber F1 to the fourth optical splitter C4 when the optical signal in the first trunk fiber F1 passes through the first optical splitter C1, so as to implement optical signal loopback from the first trunk fiber F1 to the second trunk fiber F2; the sixth optical switch K6 may also be configured to switch and send the optical signal in the second trunk fiber F2 to the second optical splitter C2 when the optical signal in the second trunk fiber F2 passes through the third optical splitter C3, so as to implement loopback of the optical signal in the direction from the second trunk fiber F2 to the first trunk fiber F1.

As shown in fig. 5 and 6, in one implementation, the subsea host node 400 includes: a first combiner 410, a second combiner 420, an optical amplifier 430, a filter 440, and two opto-electronic modules 450.

The first multiplexer 410 includes two input terminals and one output terminal. One input end of the first combiner 410 is connected to the first downlink branch optical fiber DR1, the other input end is connected to the second downlink branch optical fiber DR2, and the output end of the first combiner 410 is connected to the input end of the optical amplifier 430. The first combiner 410 is configured to transmit the downlink optical signal in the first downlink optical fiber DR1 or the second downlink optical fiber DR2 to the optical amplifier 430.

The output end of the optical amplifier 430 is connected to the input end of the filter 440, and the optical amplifier 430 is configured to transmit the downlink optical signal in the first downlink optical fiber DR1 or the second downlink optical fiber DR2 to the optical amplifier 430. It should be added that the first optical switch K1 and the third optical switch K3 enable the underwater main node 400 to receive a downlink optical signal from the first trunk optical fiber F1 or the second trunk optical fiber F2 by on-off control; when the first optical switch K1 is turned on and the third optical switch K3 is turned off, the underwater host node 400 receives a downlink optical signal from the first trunk optical fiber F1, that is, the first combiner 410 can receive a downlink optical signal from the first downlink branch optical fiber DR 1; when the third optical switch K3 is turned on and the first optical switch K1 is turned off, the underwater host node 400 receives the downlink optical signal from the second trunk optical fiber F2, that is, the first multiplexer 410 can receive the downlink optical signal from the second downlink branch optical fiber DR 2.

The optical amplifier 430 is configured to amplify the received optical signal and then transmit the amplified optical signal to the filter 440.

Filter 440 includes two outputs, each for connection to an opto-electronic module 450. The filter 440 is configured to filter the received optical signal and input the filtered optical signal to two optoelectronic modules 450.

Fig. 7 is a schematic structural diagram of another underwater main node according to an embodiment of the present application. Specifically, as shown in fig. 5 and fig. 7, the filter 440 in the underwater host node may be replaced by an optical splitter 460, in this case, the optical amplifier 430 may transmit the amplified optical signal to the optical splitter 460, the optical splitter 460 may split the optical signal transmitted by the optical amplifier 430 into two parts, and input the two parts to the two optoelectronic modules 450, respectively, and each of the optoelectronic modules 450 receives one part of the optical signal.

In this embodiment of the application, the first shore station and the second shore station may transmit the downlink optical signal to each underwater master node in a wavelength division multiplexing manner, and the downlink optical signal transmitted to each underwater master node may include two wavelength channels. Assuming that there are two underwater master nodes between the first and second shore stations, the wavelengths of the downlink optical signals transmitted to the current underwater master node may be λ 1, λ 2, and the wavelengths of the downlink optical signals transmitted to the other underwater master node may be λ 3, λ 4, and then the wavelengths of the optical signals in the first trunk optical fiber F1 and the second trunk optical fiber F2 include at least λ 1, λ 2, λ 3, and λ 4. Taking the example that the underwater host node receives the downlink optical signal of the first downlink branch optical fiber DR1, after the optical signal (λ 1, λ 2, λ 3, and λ 4) in the first trunk is split by the first optical splitter C1, the obtained downlink optical signal still includes the wavelengths λ 1, λ 2, λ 3, and λ 4, but only the optical signal of λ 1 and λ 2 is the downlink optical signal sent to the current underwater host node, so the filter 440 may filter the downlink optical signal (λ 1, λ 2, λ 3, and λ 4) to obtain the downlink optical signal (λ 1 and λ 2), and send the optical signal of λ 1 to one of the optical-to-electrical modules 450, and send the optical signal of λ 2 to the other optical-to-electrical module 450, that is, each optical-to-electrical module 450 receives the optical signal of one of the wavelengths. The two optoelectronic modules 450 are configured to perform photoelectric conversion on the received optical signal, obtain a corresponding electrical signal, and send the electrical signal to a secondary node or a junction box device.

In the embodiment of the present application, the uplink optical signal transmitted by the underwater main node to the first and second shore stations may include two wavelength channels, for example, λ 5 and λ 6. Specifically, the second combiner 420 includes two output terminals and two input terminals. Each input end of the second multiplexer 420 is used for connecting one optoelectronic module 450. Each of the optoelectronic modules 450 is configured to receive an electrical signal from a secondary node or a junction box device, convert the electrical signal into an optical signal, and send the optical signal to the second multiplexer 420, where wavelengths of the optical signals obtained by the two optoelectronic modules 450 through photoelectric conversion are different, for example, a wavelength of the optical signal obtained by one of the optoelectronic modules 450 through photoelectric conversion is λ 5, and a wavelength of the optical signal obtained by the other optoelectronic module 450 through photoelectric conversion is λ 6. One output end of the second combiner 420 is used for being connected with the first upstream branch optical fiber AD1, and the other input and output end of the second combiner is used for being connected with the second upstream branch optical fiber AD 2. The second combiner 420 is configured to converge the optical signals from the two photovoltaic modules 450, to obtain uplink optical signals (λ 5 and λ 6) with two wavelengths, and then send the uplink optical signals (λ 5 and λ 6) to the first uplink branch optical fiber AD1 and the second uplink branch optical fiber AD2, respectively, so that the uplink optical signals are received by the first shore station and the second shore station in a bidirectional manner.

In some implementations, the electrical signals, but optical signals, are transmitted between the primary and secondary nodes, and the docking box, underwater. In this case, the two optical-electrical modules 450 are specifically configured to receive an optical signal from the filter 440 or the optical splitter 460, perform optical-electrical conversion and electrical-optical conversion (i.e., two optical-electrical conversions) on the received optical signal, and send the obtained optical signal to the secondary node or the junction box device; the two photoelectric modules are further specifically configured to receive optical signals from the secondary node or the junction box device, perform photoelectric conversion and electro-optical conversion (i.e., two photoelectric conversions) on the received optical signals, obtain optical signals with two wavelengths, and send the optical signals to the second combiner.

The service implementation method of the undersea optical transmission system provided in the embodiment of the present application is further explained below.

Fig. 8 is a flowchart of an upstream service implemented by the undersea optical transmission system according to the embodiment of the present application. As shown in fig. 8, the implementation of the upstream service by the undersea optical transmission system may include the following steps S101 to S105:

and S101, converting the service electric signals of each secondary node into uplink optical signals comprising two WDM wavelength channels by the underwater main node.

In a specific implementation, each secondary node can send the service electrical signal to the primary node, so that each service electrical signal is converged at the primary node. The two photoelectric modules of the master node receive the service electrical signals and perform photoelectric conversion on the service electrical signals, and each photoelectric module can convert the service electrical signals into optical signals with one wavelength, so that the two photoelectric modules can convert the service electrical signals into optical signals with two wavelengths and send the optical signals with the two wavelengths to the second combiner. The second combiner combines the two wavelength optical signals into an upstream optical signal comprising two WDM wavelength channels.

And S102, respectively sending the uplink optical signals to the first uplink branch optical fiber and the second uplink branch optical fiber by the underwater main node.

Step S103, the optical splitting unit receives the uplink optical signals from the first uplink branch optical fiber and the second uplink branch optical fiber, merges the uplink optical signal from the first uplink branch optical fiber into the first trunk optical fiber, and merges the uplink optical signal from the second uplink branch optical fiber into the second trunk optical fiber.

Therefore, the uplink optical signal merged into the first trunk optical fiber can be transmitted towards the first shore station, and the uplink optical signal merged into the second trunk optical fiber can be transmitted towards the second shore station, so that the dual-wavelength bidirectional transmission of the uplink optical signal is realized.

And step S104, the first and second shore stations receive the uplink optical signal.

In specific implementation, the first shore station can receive an uplink optical signal from the first trunk optical fiber, and the second shore station can receive an uplink optical signal from the second trunk optical fiber, so that bidirectional reception of the uplink optical signal by the double shore stations is realized.

It should be added that, since a plurality of underwater main nodes exist between the first and second shore stations, the first and second shore stations may actually receive uplink optical signals transmitted by the plurality of underwater main nodes, and therefore, in order to distinguish the uplink optical signals transmitted by each underwater main node, the first and second shore stations further need to filter the received uplink optical signals, that is, to execute step S105.

And S105, filtering the optical signals corresponding to the underwater main nodes from the uplink optical signals by the first and second shore stations.

In this embodiment, different underwater master nodes may synthesize uplink optical signals including different WDM wavelength channels, for example, the WDM wavelength channels of the uplink optical signal synthesized by the first underwater master node may be λ 5 and λ 6, the WDM wavelength channels of the uplink optical signal synthesized by the second underwater master node may be λ 7 and λ 8, and the WDM wavelength channels of the uplink optical signal synthesized by the third underwater master node may be λ 9 and λ 10, etc. For convenience of description, in the following, the optical signals on the respective WDM wavelength channels are expressed in terms of wavelengths in the embodiments of the present application.

The first and second shore stations can filter the received uplink optical signals through the WDM filter, so as to obtain optical signals corresponding to each underwater main node. For example: if the filtered uplink optical signals are lambda 5 and lambda 6, the filtered uplink optical signals are the uplink optical signals corresponding to the first underwater main node; if the filtered uplink optical signals are lambda 7 and lambda 8, the filtered uplink optical signals are the uplink optical signals corresponding to the second underwater main node; and if the filtered uplink optical signals are lambda 9 and lambda 10, the filtered uplink optical signals are the uplink optical signals corresponding to the third underwater main node.

According to the submarine optical transmission system provided by the embodiment of the application, in an uplink service, an uplink optical signal of the underwater main node can be bidirectionally transmitted to the first shore station and the second shore station, so that even if the uplink optical signal has a transmission fault in a certain direction, the first shore station or the second shore station can receive the uplink optical signal from the other direction, and the disaster tolerance capability of the uplink service is realized.

Fig. 9 is a flowchart of a downstream service implemented by the undersea optical transmission system according to the embodiment of the present application. As shown in fig. 9, the implementation of the downstream service by the undersea optical transmission system may include the following steps S201 to S203:

step S201, the first shore station and the second shore station send downlink optical signals to the underwater main node.

In the embodiment of the present application, the downlink optical signal is bi-directionally transmitted by two devices, where: the first shore station sends a downlink optical signal through a first trunk optical fiber, and the downlink optical signal is transmitted from the first shore station to the second shore station; and the second shore station sends a downlink optical signal through a second trunk optical fiber, and the downlink optical signal is transmitted from the second shore station to the first shore station.

The first and second shore stations may simultaneously transmit downlink optical signals to the plurality of underwater master nodes. In a specific implementation, the first and second shore stations may allocate different WDM wavelength channels to downlink optical signals sent to different underwater master nodes, and each underwater master node may be allocated at least one WDM wavelength channel, for example: the WDM wavelength channels allocated for downstream optical signals sent to the first subsea master node may be λ 1 and λ 2, the WDM wavelength channels allocated for downstream optical signals sent to the second subsea master node may be λ 3 and λ 4, and so on. Thus, if the first and second shore stations simultaneously transmit downlink optical signals to the first and second underwater master nodes, the downlink optical signals transmitted by the first and second shore stations include λ 1, λ 2, λ 3, and λ 4.

Step S202, the light splitting unit sends the downlink optical signal sent by the first shore station or the second shore station to the underwater main node.

In the embodiment of the present application, downlink optical signals are transmitted bidirectionally from two directions by the first and second shore stations, and therefore, for any optical splitting unit between the first and second shore stations, it can receive downlink optical signals transmitted by the first shore station through the first trunk optical fiber and can also receive downlink optical signals transmitted by the second shore station through the second trunk optical fiber.

After the light splitting unit receives the downlink optical signals in the two directions, the downlink optical signal in one direction can be selected for light splitting, and the light split signals are sent to the underwater main node connected with the light splitting unit. In a specific implementation, if the light splitting unit selects a downlink optical signal sent by a first shore station, the downlink optical signal can be sent to a sub-main node through a first downlink branch optical fiber; if the light splitting unit selects the downlink optical signal sent by the second shore station, the downlink optical signal can be sent to the underwater main node through the second downlink branch optical fiber.

For example, the undersea optical transmission system may define one of the first and second shore stations as a main shore station, and the other shore station as an auxiliary shore station, and if the light splitting unit receives both the downlink optical signal transmitted by the main shore station and the downlink optical signal transmitted by the auxiliary shore station, the light splitting unit may split the downlink optical signal transmitted by the main shore station and transmit the split downlink optical signal to the underwater main node connected to the main shore station.

For example, if the first and second shore stations are not separated from each other, the light splitting unit may optionally split a downlink optical signal of one of the shore stations and transmit the split optical signal to the underwater main node connected to the light splitting unit.

Step S203, after the underwater host node receives the downlink optical signal, the corresponding WDM wavelength channels may be filtered from the optical signal, and then the filtered optical signals of each WDM wavelength channel are respectively sent to different optoelectronic modules.

Illustratively, if the downlink optical signal includes λ 1, λ 2, λ 3 and λ 4, and the WDM wavelength channels corresponding to the underwater master node are λ 1 and λ 2, the underwater master node may filter the optical signal with the WDM wavelength channels λ 1 and λ 2 from the downlink optical signal through a filter, and then send the optical signal λ 1 to one of the optoelectronic modules and send the optical signal λ 2 to the other optoelectronic module.

If the photoelectric module in the main node adopts coherent receiving technology, a filter is not needed, light input to the photoelectric module through the optical splitter contains lambda 1-lambda 4, and the photoelectric module adopting the coherent receiving technology can selectively receive signals of any wave in the lambda 1-lambda 4.

In the submarine optical transmission system provided by the embodiment of the application, in downlink service, the first shore station and the second shore station send downlink optical signals to the underwater main node from two directions, and the underwater main node selects the downlink optical signal in one direction to receive through the light splitting unit, so that even if the downlink optical signal has a transmission fault in one direction, the underwater main node can receive the downlink optical signal from the other direction, so that bidirectional 1+1 protection is realized, and the submarine optical transmission system has the disaster tolerance capability of uplink service.

The disaster recovery capability of the undersea optical transmission system provided in the embodiments of the present application is further described below with reference to more drawings.

Fig. 10 is a schematic WDM wavelength channel allocation diagram of an undersea optical transmission system according to an embodiment of the present application.

Fig. 11 is a schematic diagram of signal transmission when no fault occurs in the undersea optical transmission system according to the embodiment of the present application.

Illustratively, as shown in FIG. 10 and FIG. 11, the undersea optical transmission system may use a total of 40 WDM wavelength channels, and the 40 wavelength channels are numbered 1-40. Here, the numbers 1 to 40 are only used for counting 40 WDM wavelength channels, and do not correspond to wavelength numbers defined by the International Telecommunications Union (ITU). λ 1 and λ 2 are wavelength channels allocated to optical signals from a shore station to the first underwater main node 401; λ 3 and λ 4 are wavelength channels distributed from the shore station to the second underwater main node 402; λ 5 and λ 6 are wavelength channels allocated to optical signals from the first underwater main node 401 to the shore station; λ 7 and λ 8 are wavelength channels allocated to optical signals from the second underwater main node 402 to the shore station; the remaining wavelength channels are the wavelength channels of the pseudo optical DL signal. Optical signals and DL signals in the wavelength channels lambda 1-lambda 4 are generated by a shore station, and optical signals in the wavelength channels lambda 5-lambda 8 are generated by a first underwater main node 401 and a second underwater main node 402.

As further shown in fig. 10 and fig. 11, the optical signals transmitted from the first shore station to the second shore station include pseudo optical signals DL1 and λ 1, λ 2, λ 3, λ 4; at the first light splitting unit 301, the upstream optical signals λ 5 and λ 6 of the first underwater host node 401 converge into the first trunk optical fiber (i.e., the first underwater host node upwaves), and at this time, the optical signals in the first trunk optical fiber include DL1, λ 1, λ 2, λ 3, λ 4, λ 5, and λ 6; at the second optical splitting unit 302, the upstream optical signals λ 7 and λ 8 of the second underwater host node 402 are converged into the first trunk optical fiber (i.e., the second underwater host node is upgoing), and at this time, the optical signals in the first trunk optical fiber include DL1, λ 1, λ 2, λ 3, λ 4, λ 5, λ 6, λ 7, λ 8.

As further shown in fig. 10 and fig. 11, the optical signals transmitted from the second shore station to the first shore station include pseudo optical signals DL2 and λ 1, λ 2, λ 3, λ 4; at the second light splitting unit 302, the upstream optical signals λ 7 and λ 8 of the second underwater main node 402 are converged into the second trunk optical fiber (i.e., the second underwater main node is upgoing), and at this time, the optical signals in the second trunk optical fiber include DL2, λ 1, λ 2, λ 3, λ 4, λ 7, and λ 8; at the first light splitting unit 301, the upstream optical signals λ 5 and λ 6 of the first underwater main node 401 converge into the second trunk optical fiber (i.e., the first underwater main node upwaves), and at this time, the optical signals in the second trunk optical fiber include DL2, λ 1, λ 2, λ 3, λ 4, λ 5, λ 6, λ 7, λ 8.

As can be seen from fig. 10 and 11, when the submarine optical transmission system is not in fault, the downlink optical signals λ 1, λ 2, λ 3, and λ 4 may be sent to the first underwater master node 401 and the second underwater master node 402 from two directions, and the uplink optical signals λ 5, λ 6, λ 7, and λ 8 may also be sent to the first shore station and the second shore station from two directions, so as to implement 1+1 protection capability.

Next, taking an example that the submarine optical transmission system has a trunk optical fiber cable break fault between the second optical splitter unit 302 and the second shore station, a trunk disaster recovery process of the submarine optical transmission system will be specifically described.

Fig. 12a, 12b, and 12c are flowcharts illustrating a main line disaster recovery of the undersea optical transmission system according to an embodiment of the present application.

As shown in fig. 12a, when a trunk fiber cable break fault occurs in the undersea optical transmission system between the second optical splitting unit 302 and the second shore station, the optical signal transmitted from the first shore station to the second shore station cannot be transmitted to the second optical splitting unit 302. At this time, in the second trunk optical fiber, the optical signal between the second optical splitting unit 302 and the first optical splitting unit 301 includes only λ 7 and λ 8, and the optical signal between the first optical splitting unit 301 and the first shore station includes only λ 5, λ 6, λ 7 and λ 8, so that there is no spurious optical signal, which has the problems of large nonlinear cost and influence on the service transmission quality.

As shown in fig. 12b, when detecting that a trunk fiber cable breaking fault occurs between a second shore station and a second optical splitting unit 302 adjacent to the second shore station, the first shore station sends a monitoring signal to each optical splitting unit, and the first optical splitting unit 301 cuts off any one of the road uplink optical signals of the corresponding first underwater main node 401 according to the monitoring signal.

As shown in fig. 12c, the second optical splitting unit 302 loops the optical signal in the first trunk fiber back to the second trunk fiber according to the supervisory signal. Thus, in the second trunk fiber, the optical signal between the second optical splitting unit 302 and the first optical splitting unit 301 includes DL1, λ 1, λ 2, λ 3, λ 4, λ 7, and λ 8, and the optical signal between the first optical splitting unit 301 and the first shore station includes DL1, λ 1, λ 2, λ 3, λ 4, λ 5, λ 6, λ 7, and λ 8, thereby implementing a disaster tolerance process.

Next, taking an example that the submarine optical transmission system has a branch optical fiber cable break fault between the second optical splitter unit 302 and the second underwater main node 402 or the second underwater main node 402 has a fault, a branch disaster recovery process of the submarine optical transmission system will be specifically described.

Fig. 13a, 13b, and 13c are flowcharts illustrating a branch disaster recovery of an undersea optical transmission system according to an embodiment of the present application.

As shown in fig. 13a, when the submarine optical transmission system has a branch optical fiber cable break fault between the second optical splitting unit 302 and the second underwater main node 402 or the second underwater main node 402 has a fault, the uplink optical signal of the second underwater main node 402 cannot be transmitted to the second optical splitting unit 302. At this time, in the first trunk fiber, the optical signal between the second light splitting unit 302 and the second shore station includes DL1, λ 1, λ 2, λ 3, λ 4, λ 5, λ 6, and lacks λ 7, λ 8; in the second trunk fiber, the optical signal between the second optical splitting unit 302 and the first optical splitting unit 301 includes DL2, λ 1, λ 2, λ 3, λ 4, and lacks λ 7, λ 8; the optical signal between the first light splitting unit 301 and the first shore station comprises DL2, λ 1, λ 2, λ 3, λ 4, λ 5, λ 6, lacking λ 7, λ 8.

As shown in fig. 13b, when a branch optical fiber cable breaking fault occurs between any underwater main node and the light splitting unit, the first or second shore station sends a monitoring signal to the light splitting unit on the faulty branch optical fiber. For example: after detecting that a branch optical fiber cable breaking fault occurs between the second light splitting unit 302 and the second underwater main node 402 or that the second underwater main node 402 has a fault in the submarine optical transmission system, the first shore station or the second shore station sends a monitoring signal to the second light splitting unit 302, and the second light splitting unit 302 closes the two-way uplink optical signal sent by the second underwater main node 402 to the first shore station and the second shore station according to the monitoring signal.

As shown in fig. 13c, the first and second shore stations supplement the WDM channels occupied by the upstream optical signals of the underwater main node on the faulty branch optical fiber with dummy optical signals. For example: the first and second shore stations adjust the spurious optical signals to supplement the WDM wavelength channels occupied by the upstream optical signal of the second underwater host node 402 with spurious optical signals λ 7 (DL) and λ 8 (DL). Thus, in the first trunk fiber, the optical signal between the first land station and the first light splitting unit 301 includes DL1, λ 7 (DL), λ 8 (DL), λ 1, λ 2, λ 3, λ 4, the optical signal between the first light splitting unit 301 and the second light splitting unit 302 includes DL1, λ 7 (DL), λ 8 (DL), λ 1, λ 2, λ 3, λ 4, λ 5, λ 6, and the optical signal between the second light splitting unit 302 and the second land station includes DL1, λ 7 (DL), λ 8 (DL), λ 1, λ 2, λ 3, λ 4, λ 5, λ 6; in the second trunk fiber, the optical signal between the second optical splitting unit 302 and the second land station includes DL2, λ 7 (DL), λ 8 (DL), λ 1, λ 2, λ 3, λ 4, the optical signal between the second optical splitting unit 302 and the first optical splitting unit 301 includes DL2, λ 7 (DL), λ 8 (DL), λ 1, λ 2, λ 3, λ 4, and the optical signal between the first optical splitting unit 301 and the first land station includes DL2, λ 7 (DL), λ 8 (DL), λ 1, λ 2, λ 3, λ 4, λ 5, λ 6. Thereby implementing a disaster recovery process.

The submarine optical transmission system provided by the embodiment of the application can be applied to a submarine observation network system with high uplink and downlink service capacity and high bandwidth requirement, can realize service protection and disaster recovery processes when trunk optical fibers or branch optical fibers of the submarine observation network system have faults, and improves the reliability of the submarine observation network.

Some submarine observation network systems have low requirements on capacity of downlink services, but have more expandable underwater main nodes, for example, the downlink services only include a shore station for issuing management information to the underwater main nodes, and the requirements on time synchronism and real-time performance are not high or have no requirements, at this time, if a pair of WDM wavelength channels is independently allocated to each underwater main node, the number of the required WDM wavelength channels is multiplied with the increase of the number of the underwater main nodes, so that 40 WDM wavelength channels of the system cannot meet the requirements of more main nodes. Therefore, in order to reduce the occupation of the WDM wavelength channels and improve the expansibility of the submarine observation network system, the embodiment of the present application may further enable the downlink optical signals of all the underwater master nodes to multiplex a pair of WDM wavelength channels, that is, the downlink optical signals of each underwater master node are transmitted using the same pair of WDM wavelength channels no matter there are several underwater master nodes between the first shore station and the second shore station (for short, multiplexing scheme). The multiplexing scheme of the downlink optical signals can be time division multiplexing or message distribution, and the like, which is not limited in the embodiment of the application, and each underwater master node analyzes the corresponding message segment after receiving the downlink optical signals.

The disaster recovery capability of the multiplexing scheme is further explained below with reference to more figures.

Fig. 14 is a schematic WDM wavelength channel allocation diagram of an undersea optical transmission system of a multiplexing scheme shown in an embodiment of the present application.

Fig. 15 is a schematic diagram of signal transmission when the submarine optical transmission system of the multiplexing scheme according to the embodiment of the present application is not in failure.

Illustratively, as shown in FIG. 14 and FIG. 15, the undersea optical transmission system may use 40 WDM wavelength channels, and the 40 wavelength channels are numbered 1-40. Here, the numbers 1 to 40 are only used for counting 40 WDM wavelength channels, and do not correspond to wavelength numbers defined by the International Telecommunications Union (ITU). The wavelength channels of the downlink optical signal multiplexing of the main nodes lambda 1 and lambda 2; λ 5 and λ 6 are wavelength channels used by the upstream optical signal of the first underwater master node 401; λ 7 and λ 8 are wavelength channels used by the upstream optical signal of the second underwater master node 402; the remaining wavelength channels are the wavelength channels of the pseudo optical DL signal. The optical signals and DL signals of the wavelength channels lambda 1 and lambda 2 are generated by a shore station, and the optical signals of the wavelength channels lambda 5-lambda 8 are generated by a first underwater main node 401 and a second underwater main node 402.

As further shown in fig. 14 and fig. 15, the optical signal transmitted from the first land station to the second land station includes the dummy optical signal DL1 and λ 1, λ 2; at the first light splitting unit 301, the upstream optical signals λ 5 and λ 6 of the first underwater host node 401 converge into the first trunk optical fiber (i.e., the first underwater host node upwaves), and at this time, the optical signals in the first trunk optical fiber include DL1, λ 1, λ 2, λ 5 and λ 6; at the second optical splitting unit 302, the upstream optical signals λ 7 and λ 8 of the second underwater main node 402 are converged into the first trunk optical fiber (i.e., the second underwater main node is upgoing), and at this time, the optical signals in the first trunk optical fiber include DL1, λ 1, λ 2, λ 5, λ 6, λ 7, λ 8.

As further shown in fig. 14 and fig. 15, the optical signal transmitted from the second land station to the first land station includes the dummy optical signal DL2 and λ 1, λ 2; at the second optical splitting unit 302, the upstream optical signals λ 7 and λ 8 of the second underwater main node 402 are converged into the second trunk optical fiber (i.e., the second underwater main node is upgoing), and at this time, the optical signals in the second trunk optical fiber include DL2, λ 1, λ 2, λ 7 and λ 8; at the first light splitting unit 301, the upstream optical signals λ 5 and λ 6 of the first underwater main node 401 converge into the second trunk optical fiber (i.e., the first underwater main node upwaves), and at this time, the optical signals in the second trunk optical fiber include DL2, λ 1, λ 2, λ 5, λ 6, λ 7, λ 8.

As can be seen from fig. 14 and 15, when the submarine optical transmission system is not in fault, the downlink optical signals λ 1 and λ 2 may be sent to the first underwater master node 401 and the second underwater master node 402 from two directions, and the uplink optical signals λ 5, λ 6, λ 7, and λ 8 may also be sent to the first shore station and the second shore station from two directions, so as to implement 1+1 protection capability.

Fig. 16a, 16b, and 16c are flowcharts of the trunk disaster recovery of the undersea optical transmission system of the multiplexing scheme according to the embodiment of the present application.

As shown in fig. 16a, when a trunk fiber cable break fault occurs in the undersea optical transmission system between the second optical splitting unit 302 and the second shore station, the optical signal transmitted from the first shore station to the second shore station cannot be transmitted to the second optical splitting unit 302. At this time, in the second trunk optical fiber, the optical signal between the second optical splitting unit 302 and the first optical splitting unit 301 includes only λ 7 and λ 8, and the optical signal between the first optical splitting unit 301 and the first shore station includes only λ 5, λ 6, λ 7 and λ 8, so that there is no spurious optical signal, which has the problems of large nonlinear cost and influence on the service transmission quality.

As shown in fig. 16b, after a trunk fiber cable breaking fault occurs between the second optical splitting unit 302 and the second shore station, the first shore station transmits a monitoring signal to the first optical splitting unit 301, and the first optical splitting unit 301 turns off an uplink optical signal transmitted from the first underwater main node 401 to the second shore station according to the monitoring signal.

Next, as shown in fig. 16c, the first shore station transmits a monitoring signal to the second optical splitting unit 302, and the second optical splitting unit 302 loops the optical signal in the first trunk optical fiber back to the second trunk optical fiber according to the monitoring signal. Thus, in the second trunk fiber, the optical signal between the second optical splitting unit 302 and the first optical splitting unit 301 includes DL1, λ 1, λ 2, λ 7, and λ 8, and the optical signal between the first optical splitting unit 301 and the first shore station includes DL1, λ 1, λ 2, λ 5, λ 6, λ 7, λ 8. Thereby implementing a disaster recovery process.

As shown in fig. 17a, when the submarine optical transmission system has a branch optical fiber cable break fault between the second optical splitting unit 302 and the second underwater main node 402 or the second underwater main node 402 has a fault, the uplink optical signal of the second underwater main node 402 cannot be transmitted to the second optical splitting unit 302. At this time, in the first trunk fiber, the optical signal between the second light splitting unit 302 and the second shore station includes DL1, λ 1, λ 2, λ 5, λ 6, and lacks λ 7, λ 8; in the second trunk fiber, the optical signal between the second optical splitting unit 302 and the first optical splitting unit 301 includes DL2, λ 1, λ 2, and lacks λ 7, λ 8; the optical signal between the first light splitting unit 301 and the first shore station comprises DL2, λ 1, λ 2, λ 5, λ 6, lacking λ 7, λ 8.

As shown in fig. 17b, after a branch optical fiber cable breaking fault occurs between the second optical splitting unit 302 and the second underwater main node 402 or the second underwater main node 402 has a fault, the first shore station or the second shore station transmits a monitoring signal to the second optical splitting unit 302, and the second optical splitting unit 302 turns off the two-way uplink optical signal transmitted by the second underwater main node 402 to the first shore station and the second shore station according to the monitoring signal.

Next, as shown in fig. 17c, the first and second shore stations adjust the dummy optical signals, and the WDM wavelength channels occupied by the upstream optical signal of the second underwater master node 402 are supplemented with dummy optical signals λ 7 (DL) and λ 8 (DL). Thus, in the first trunk fiber, the optical signal between the first optical splitting unit 301 and the first land station includes DL1, λ 7 (DL), λ 8 (DL), λ 1, λ 2, the optical signal between the first optical splitting unit 301 and the second optical splitting unit 302 includes DL1, λ 7 (DL), λ 8 (DL), λ 1, λ 2, λ 5, λ 6, and the optical signal between the second optical splitting unit 302 and the second land station includes DL1, λ 7 (DL), λ 8 (DL), λ 1, λ 2, λ 5, λ 6; in the second trunk fiber, the optical signal between the second land station and the second optical splitting unit 302 includes DL2, λ 7 (DL), λ 8 (DL), λ 1, λ 2, the optical signal between the second optical splitting unit 302 and the first optical splitting unit 301 includes DL2, λ 7 (DL), λ 8 (DL), λ 1, λ 2, and the optical signal between the first optical splitting unit 301 and the first land station includes DL2, λ 7 (DL), λ 8 (DL), λ 1, λ 2, λ 5, λ 6. Thereby implementing a disaster recovery process.

The submarine optical transmission system provided by the embodiment of the application multiplexes downlink optical signals of all underwater main nodes by the same pair of WDM wavelength channels, can improve the utilization rate of optical bandwidth, is suitable for submarine observation network systems with low requirements on downlink service capacity or more underwater nodes and high requirements on node expansion capacity, can realize service protection and disaster recovery processes when trunk optical fibers or branch optical fibers of the submarine observation network systems have faults, and improves the reliability of the submarine observation network.

It is understood that a person skilled in the art can combine, split, recombine and the like the embodiments of the present application to obtain other embodiments on the basis of several embodiments provided by the present application, and the embodiments do not depart from the scope of the present application.

The above embodiments are only intended to be specific embodiments of the present application, and are not intended to limit the scope of the embodiments of the present application, and any modifications, equivalent substitutions, improvements, and the like made on the basis of the technical solutions of the embodiments of the present application should be included in the scope of the embodiments of the present application.

Claims

1. An undersea optical transmission system, comprising:

the first shore station and the second shore station are connected through a first trunk optical fiber and a second trunk optical fiber, the first trunk optical fiber is used for transmitting optical signals from the first shore station to the second shore station, and the second trunk optical fiber is used for transmitting optical signals from the second shore station to the first shore station;

each light splitting unit is correspondingly provided with an underwater main node and is connected with the underwater main node through a first downlink branch optical fiber, a second downlink branch optical fiber, a first uplink branch optical fiber and a second uplink branch optical fiber; the light splitting unit includes: the first optical switch, the second optical switch, the third optical switch, the fifth optical switch and the sixth optical switch are connected in series;

the first optical switch is arranged between the first optical splitter and the first downlink branch optical fiber and used for controlling the on-off of the downlink optical signal in the first downlink branch optical fiber;

the second optical splitter is arranged on the light-emitting side of the first trunk optical fiber and used for receiving the uplink optical signal of the underwater main node through the first uplink branch optical fiber and combining the uplink optical signal in the first uplink branch optical fiber into the first trunk optical fiber, and the second optical switch is arranged between the second optical splitter and the first uplink branch optical fiber and used for controlling the on-off of the uplink optical signal in the first uplink branch optical fiber;

the third optical splitter is arranged on the light inlet side of the second trunk optical fiber and used for splitting a downlink optical signal from the second trunk optical fiber and sending the downlink optical signal split from the second trunk optical fiber to the underwater main node through the second downlink branch optical fiber, and the third optical switch is arranged between the third optical splitter and the second downlink branch optical fiber and used for controlling the on-off of the downlink optical signal in the second downlink branch optical fiber;

the first optical switch and the third optical switch are used for enabling the underwater main node to select one of the first trunk optical fiber and the second trunk optical fiber to receive the downlink optical signal through on-off control;

the fourth optical switch is arranged between the fourth optical splitter and the second uplink branch optical fiber and is used for controlling the on-off of the uplink optical signal in the second uplink branch optical fiber;

the fifth optical switch and the sixth optical switch are arranged in series to form an optical path between the first optical splitter and the second optical splitter and an optical path between the third optical splitter and the fourth optical splitter; according to the requirement, the fifth optical switch may be further configured to send the optical signal in the first trunk optical fiber to the fourth optical splitter when the optical signal in the first trunk optical fiber passes through the first optical splitter, so as to implement optical signal loopback from the first trunk optical fiber to the second trunk optical fiber; according to the requirement, the sixth optical switch may be further configured to send the optical signal in the second trunk optical fiber to the second optical splitter when the optical signal in the second trunk optical fiber passes through the third optical splitter, so as to implement optical signal loopback from the second trunk optical fiber to the first trunk optical fiber;

the underwater main node comprises a first wave combiner, a second wave combiner, two photoelectric modules of an optical amplifier, a filter and any one of a light splitter;

the input end of the first wave combiner is connected with the first downlink branch optical fiber and the second downlink branch optical fiber and is used for sending downlink optical signals in the first downlink branch optical fiber or the second downlink branch optical fiber to an optical amplifier;

the optical amplifier is used for amplifying the received optical signal and then sending the amplified optical signal to the filter or the optical splitter;

when the underwater main node comprises the filter, the filter is used for filtering the received optical signals to obtain optical signals with two wavelengths and sending the optical signals to the two photoelectric modules, and each photoelectric module receives the optical signal with one wavelength;

when the underwater main node comprises the optical splitter, the optical splitter is used for splitting the received optical signals into two parts and sending the two parts to the two photoelectric modules, and each photoelectric module receives one part of the optical signals;

the two photoelectric modules are used for receiving optical signals from the filter or the optical splitter and sending the received optical signals to a secondary node or junction box equipment in the form of optical signals or electric signals;

the two photoelectric modules are also used for receiving electric signals or optical signals from the secondary node or the junction box device, and sending the received electric signals or optical signals to the second wave combiner in the form of optical signals with two wavelengths;

the second combiner is configured to converge optical signals from the two photovoltaic modules to obtain the uplink optical signal including two wavelengths, and send the uplink optical signal to the first uplink branch optical fiber and the second uplink branch optical fiber, so that the uplink optical signal is received by the first shore station and the second shore station in a bidirectional manner.

2. The undersea optical transmission system of claim 1,

the two photoelectric modules are specifically used for receiving optical signals from the filter or the optical splitter, performing photoelectric conversion on the received optical signals to obtain corresponding electric signals, and sending the corresponding electric signals to the secondary node or the junction box device;

the two photoelectric modules are further specifically configured to receive an electrical signal from the secondary node or the junction box device, perform electro-optical conversion on the received electrical signal, obtain optical signals with two wavelengths, and send the optical signals to the second combiner.

3. The undersea optical transmission system of claim 1,

the two photoelectric modules are specifically used for receiving optical signals from the filter or the optical splitter, performing photoelectric conversion and electro-optical conversion on the received optical signals, and sending the obtained optical signals to the secondary node or the junction box device;

the two photoelectric modules are further specifically configured to receive optical signals from the secondary node or the junction box device, perform photoelectric conversion and electro-optical conversion on the received optical signals, obtain optical signals with two wavelengths, and send the optical signals to the second multiplexer.

4. The undersea optical transmission system of claim 1 wherein said undersea optical transmission system transmits optical signals over a plurality of wavelength division multiplexed WDM channels, a portion of said WDM channels being used to transmit said upstream optical signal and said downstream optical signal, said upstream optical signal and said downstream optical signal occupying different WDM channels, the remaining WDM channels being used to transmit dummy optical DL signals.

5. The undersea optical transmission system of claim 4 wherein said first and second shore stations transmit downstream optical signals to each of said underwater host nodes using two WDM channels, the WDM channels corresponding to different ones of said underwater host nodes being different.

6. The undersea optical transmission system of claim 4 wherein said first and second land stations transmit said downstream optical signals to each of said underwater host nodes in a time division multiplexed or segment distributed manner over two WDM channels.

7. The undersea optical transmission system of claim 5 wherein each of said subsea master nodes transmits upstream optical signals to said first and second land stations that each occupy two WDM channels, the upstream optical signals transmitted by different ones of said subsea master nodes occupying different WDM channels.

8. The undersea optical transmission system of any one of claims 4-7,

when a trunk optical fiber cable breaking fault occurs between the second shore station and the light splitting unit adjacent to the second shore station, the first shore station is used for sending monitoring signals to the light splitting units; and the light splitting units near the fault point of the cable breaking fault are used for looping the optical signal in the first trunk optical fiber back to the second trunk optical fiber according to the monitoring signal, and the other light splitting units are used for cutting off any one-way uplink optical signal of the corresponding underwater main node according to the monitoring signal.

9. The undersea optical transmission system of any one of claims 4-7,

when a trunk optical fiber cable breaking fault occurs between the first shore station and the adjacent light splitting unit, the second shore station is used for sending monitoring signals to the light splitting units; the light splitting unit adjacent to the first shore station is used for returning the optical signal in the second trunk optical fiber to the first trunk optical fiber according to the monitoring signal; and the other light splitting units are used for cutting off any one path of uplink optical signals of the corresponding underwater main node according to the monitoring signals.

10. The undersea optical transmission system of any one of claims 4-7,

when a branch optical fiber cable breaking fault occurs between any one underwater main node and the light splitting unit, the first shore station or the second shore station is used for sending a monitoring signal to the light splitting unit on the fault branch optical fiber; the light splitting unit on the fault branch optical fiber is used for cutting off two uplink optical signals of the underwater main node on the fault branch optical fiber according to the monitoring signal; and the first and second shore stations are used for supplementing the WDM channel occupied by the uplink optical signal of the underwater main node on the fault branch optical fiber with a false optical signal.

11. The undersea optical transmission system of any one of claims 4-7,

when any one of the underwater main nodes breaks down, the first shore station or the second shore station is used for sending a monitoring signal to the light splitting unit corresponding to the broken-down underwater main node; the light splitting unit corresponding to the failed underwater main node is used for cutting off two paths of uplink optical signals of the failed underwater main node according to the monitoring signal; the first and second shore stations are used for supplementing WDM channels occupied by uplink optical signals of the underwater main node with the fault by using false optical signals.

12. A disaster recovery method applied to the undersea optical transmission system according to any one of claims 1 to 11, the method comprising:

when the first shore station detects that a trunk optical fiber cable breaking fault occurs between the second shore station and the adjacent light splitting unit, a monitoring signal is sent to each light splitting unit;

and the light splitting units adjacent to the second shore station loop the optical signals in the first trunk optical fiber back to the second trunk optical fiber according to the monitoring signals, and the rest of the light splitting units cut off any one of the road uplink optical signals of the corresponding underwater main node according to the monitoring signals.

13. A disaster recovery method applied to the undersea optical transmission system according to any one of claims 1 to 11, the method comprising:

when the first shore station or the second shore station detects that a branch optical fiber cable breaking fault occurs between any one underwater main node and the light splitting unit, a monitoring signal is sent to the light splitting unit on a fault branch optical fiber;

the light splitting unit on the fault branch optical fiber cuts off two uplink optical signals of the underwater main node on the fault branch optical fiber according to the monitoring signal;

and the first and second shore stations supplement the WDM channel occupied by the uplink optical signal of the underwater main node on the fault branch optical fiber by using a false optical signal.

14. A disaster recovery method applied to the undersea optical transmission system according to any one of claims 1 to 11, the method comprising:

when the first shore station or the second shore station detects that any one underwater main node fails, a monitoring signal is sent to the light splitting unit corresponding to the failed underwater main node;

the light splitting unit corresponding to the underwater main node with the fault cuts off two paths of uplink optical signals of the underwater main node with the fault according to the monitoring signal;

and the first and second shore stations supplement WDM channels occupied by uplink optical signals of the underwater main node with faults by using false optical signals.