Submarine optical communication system, its control method, and control program

Abstract

A seabed optical communication system (SYS1) comprises: a first multi-core fiber (3, MCF1) through which an optical signal used for communication between a plurality of terminal station devices (1_1 to 1_4) is transmitted; and a first seabed instrument (2_1) and a second seabed instrument (2_2) that are each provided at a relay point of the first multi-core fiber and are configured to be able to switch connections of a plurality of first cores constituting the first multi-core fiber. At least one of the plurality of terminal station devices (1_1 to 1_4) includes: a monitoring circuit (101); and a control circuit (102) that, when having determined that there is a malfunction in one of a plurality of first partial cores constituting a first partial multi-core fiber provided between the first seabed instrument (2_1) and the second seabed instrument (2_2) in the first multi-core fiber, switches the transmission path of the optical signal that had been transmitted by the first partial core determined as having a malfunction, to another first partial core through which an optical signal having low priority is transmitted.

Description

Submarine optical communication system, its control method, and non-transitory computer-readable medium storing a control program

[0001] The present disclosure relates to a submarine optical communication system, a control method thereof, and a non-transitory computer-readable medium on which a control program is stored.

[0002] A submarine optical communication system comprises multiple terminal devices installed on land, submarine cables that transmit communications between them, and submarine equipment installed at relay points of the submarine cables. The submarine equipment transmits, relays, and branches optical signals propagating through the submarine cables.

[0003] In recent years, there has been a demand for increased transmission capacity in submarine optical communication systems. To meet this demand, the use of submarine cables made of multicore fibers, which are composed of multiple cores, has been considered for submarine optical communication systems.

[0004] Technologies relating to submarine optical communication systems are disclosed in, for example, Patent Document 1, Patent Document 2, Patent Document 3, and Patent Document 4. In these related technologies, when a multicore fiber of a cable fails, the transmission path of a signal transmitted through the failed multicore fiber is switched to a spare multicore fiber.

[0005] JP 2014-165595 A JP 2015-109515 A JP 2016-111480 A International Publication No. 2022 / 054536

[0006] However, the related technology has a problem in that it is necessary to provide a spare multi-core fiber or spare cores in the cable, which increases costs.

[0007] The present disclosure has been made to solve such problems, and aims to provide a submarine optical communication system that can suppress cost increases by optimizing communication without using a spare multicore fiber or spare cores even when a failure occurs in the multicore fiber of a cable, a control method thereof, and a non-transitory computer-readable medium storing a control program.

[0008] A submarine optical communication system according to the present disclosure comprises a plurality of terminal devices; a first multicore fiber composed of a plurality of first cores that transmits optical signals used for communication between the plurality of terminal devices; and first and second submarine devices that are provided at relay points of the first multicore fiber and are configured to be able to switch the connection of the plurality of first cores that constitute the first multicore fiber, wherein at least one of the plurality of terminal devices comprises: a monitoring circuit that monitors the signal transmission status of the first multicore fiber; and a control circuit that, when it is determined by the monitoring circuit that one of the plurality of first partial cores that constitutes a first partial multicore fiber of the first multicore fiber that is provided between the first submarine device and the second submarine device is faulty, switches the transmission path of the optical signal that has been transmitted by the first partial core determined to be faulty to another first partial core that transmits an optical signal having a lower priority than the first partial core determined to be faulty.

[0009] A control method for a submarine optical communication system according to the present disclosure is a control method for a submarine optical communication system comprising a plurality of terminal devices, a first multicore fiber composed of a plurality of first cores that transmits optical signals used for communication between the plurality of terminal devices, and first and second submarine equipment that are provided at relay points of the first multicore fiber and are configured to be able to switch the connection of the plurality of first cores that constitute the first multicore fiber, wherein the control method monitors the signal transmission status of the first multicore fiber using at least one of the plurality of terminal devices, and when it is determined that any of the plurality of first partial cores that constitute a first partial multicore fiber of the first multicore fiber that is provided between the first submarine equipment and the second submarine equipment has failed, the control method switches the transmission path of the optical signal that has been transmitted by the first partial core determined to be failed to another first partial core that transmits an optical signal having a lower priority than the first partial core determined to be failed.

[0010] A non-transitory computer-readable medium storing a control program according to the present disclosure is a non-transitory computer-readable medium storing a control program that causes a computer to execute control processing in a submarine optical communication system including a plurality of terminal devices, a first multi-core fiber composed of a plurality of first cores that transmits optical signals used for communication between the plurality of terminal devices, and first and second submarine equipment that are provided at relay points of the first multi-core fiber and are configured to be able to switch the connection of the plurality of first cores that constitute the first multi-core fiber, wherein the control program stored causes a computer to execute the following processing: monitoring a signal transmission status of the first multi-core fiber using at least one of the plurality of terminal devices; and, when it is determined that one of a plurality of first partial cores that constitute a first partial multi-core fiber provided between the first submarine equipment and the second submarine equipment of the first multi-core fiber has failed, switching the transmission path of the optical signal that has been transmitted by the first partial core that has been determined to have failed to another first partial core that transmits an optical signal that has a lower priority than the first partial core that has been determined to have failed.

[0011] The present disclosure makes it possible to provide a submarine optical communication system that can suppress cost increases by optimizing communication without using a spare multicore fiber or spare core even when a failure occurs in the multicore fiber of a cable, a control method thereof, and a non-transitory computer-readable medium storing a control program.

[0012] FIG. 1 is a block diagram showing an example of the configuration of a submarine optical communication system according to a first embodiment. FIG. 2 is a diagram for explaining the operation of the submarine optical communication system shown in FIG. 1. FIG. 3 is a block diagram showing an example of the configuration of a submarine optical communication system according to a second embodiment. FIG. 4 is a diagram for explaining the operation of the submarine optical communication system shown in FIG. 3. FIG. 5 is a block diagram showing an example of the configuration of a submarine optical communication system according to a third embodiment. FIG. 6 is a diagram for explaining the operation of the submarine optical communication system shown in FIG. 5. FIG. 7 is a diagram for explaining the operation of the submarine optical communication system shown in FIG. 5. FIG. 8 is a diagram for explaining the operation of the submarine optical communication system shown in FIG. 5. FIG. 9 is a diagram for explaining the operation of the submarine optical communication system shown in FIG. 5. FIG. 10 is a block diagram showing a modified example of a terminal device.

[0013] Hereinafter, embodiments will be described with reference to the drawings. Note that the drawings are simplified, and the technical scope of the embodiments should not be narrowly interpreted based on the description in the drawings. Furthermore, identical elements are given the same reference numerals, and duplicate explanations will be omitted.

[0014] In the following embodiments, when necessary for convenience, the description will be divided into multiple sections or embodiments. However, unless otherwise specified, they are not unrelated to each other, and one is a partial or complete modification, application example, detailed explanation, supplementary explanation, etc. of the other. Furthermore, in the following embodiments, when the number of elements (including the number, numerical value, amount, range, etc.) is mentioned, it is not limited to that specific number, and may be more or less than the specific number, unless otherwise specified or when it is clearly limited to a specific number in principle.

[0015] Furthermore, in the following embodiments, the components (including operational steps, etc.) are not necessarily essential unless otherwise specified or considered to be clearly essential in principle. Similarly, in the following embodiments, when referring to the shape, positional relationship, etc. of components, etc., it is intended to include those that are substantially similar or similar to the shape, etc., unless otherwise specified or considered to be clearly not essential in principle. The same applies to the above numbers, etc. (including numbers, numerical values, amounts, ranges, etc.).

[0016] <First Embodiment> Fig. 1 is a block diagram showing an example of the configuration of a submarine optical communication system SYS1 according to a first embodiment. Fig. 2 is a diagram for explaining the operation of the submarine optical communication system SYS1.

[0017] 1, the submarine optical communication system SYS1 includes a plurality of terminal devices 1, a plurality of submarine devices 2, and a submarine cable 3. In this embodiment, an example will be described in which the submarine optical communication system SYS1 includes four terminal devices 1_1 to 1_4 as the plurality of terminal devices 1, and two submarine devices 2_1 to 2_2 as the plurality of submarine devices 2.

[0018] The terminal devices 1_1 to 1_4 are installed on land and configured to be able to communicate with each other via a submarine cable 3. Each of the terminal devices 1_1 to 1_4 includes, for example, a WME (Wavelength Multiplexing Equipment), an OCI (Open Cable Interface), an SLTE (Subscriber Line Terminal Equipment), a TPND (Transponder), etc. At least one of the terminal devices 1_1 to 1_4 includes a monitoring circuit 101 and a control circuit 102. In this embodiment, an example will be described in which the terminal device 1_1 includes the monitoring circuit 101 and the control circuit 102.

[0019] The submarine cable 3 is an optical fiber cable that transmits optical signals used for communication between the terminal devices 1_1 to 1_4. Specifically, the submarine cable 3 includes a multi-core fiber configured with multiple cores. In this embodiment, as shown in Figure 2, an example will be described in which the submarine cable 3 includes a multi-core fiber MCF1 configured with four cores.

[0020] Each of the submarine devices 2_1 to 2_2 is provided at a relay point (under the sea) of the submarine cable 3, and transmits, relays, and branches optical signals propagating through the submarine cable 3. In addition, the submarine devices 2_1 to 2_2 are configured to be able to switch the connection of four cores that make up the multi-core fiber MCF1 included in the submarine cable 3.

[0021] Here, in the terminal device 1_1, the monitoring circuit 101 monitors the signal transmission status of the submarine cable 3. In other words, the monitoring circuit 101 monitors the signal transmission status of the multi-core fiber MCF1 included in the submarine cable 3.

[0022] Based on the monitoring results of the monitoring circuit 101, the control circuit 102 causes the submarine devices 2_1 to 2_2 to switch the connections of the four cores that make up the multi-core fiber MCF1. Note that a priority of the optical signal to be transmitted is set for each core. Cores that transmit optical signals with low priority include cores for which transmission of optical signals has temporarily stopped.

[0023] Specifically, when the monitoring circuit 101 determines that any of the cores (first partial cores) C1a to C1d constituting the multicore fiber (first partial multicore fiber) MCF1_1 provided between the submarine equipment 2_1 and the submarine equipment 2_2 in the multicore fiber MCF1 has failed, the control circuit 102 switches the transmission path of the optical signal transmitted by the core determined to have failed to another core that transmits an optical signal with a lower priority than the core determined to have failed.

[0024] For example, if the monitoring circuit 101 determines that core C1a, which is one of cores C1a to C1d that constitute the multicore fiber MCF1, which is provided between the submarine equipment 2_1 and the submarine equipment 2_2, is faulty, the control circuit 102 switches the transmission path of the optical signal that was being transmitted by core C1a to core C1d that transmits an optical signal with a lower priority than core C1a.

[0025] As described above, the submarine optical communication system SYS1 according to the present embodiment can optimize communication even when a failure occurs in the submarine cable 3, without using a spare multicore fiber or a spare core, thereby reducing the costs associated with the spare multicore fiber and the spare core.

[0026] Furthermore, in the submarine optical communication system SYS1 according to this embodiment, for example, among the cores of the submarine cable 3 installed between the terminal equipment 1_1 and the terminal equipment 1_2, it is only necessary to switch the connection of only the core portion between two submarine devices where a fault has occurred to another core, thereby preventing momentary interruptions in cores where no fault has occurred.

[0027] In the present embodiment, the control circuit 102 switches the connection of multiple cores constituting the multi-core fiber provided between the submarine device 2_1 and the submarine device 2_2 in the multi-core fiber MCF1, but this is not limiting. For example, the control circuit 102 may be configured to switch the connection of multiple cores constituting the multi-core fiber provided between the terminal device 1_1 and the submarine device 2_1 in the multi-core fiber MCF1.

[0028] In addition, in this embodiment, the submarine optical communication system SYS1 is described as having two submarine devices 2_1 and 2_2, but this is not limiting. The submarine optical communication system SYS1 can be appropriately modified to have three or more submarine devices 2_1 to 2_n (n is an integer of 3 or more).

[0029] <Second embodiment> Fig. 3 is a block diagram showing an example of the configuration of a submarine optical communication system SYS2 according to a second embodiment. Also, Fig. 4 is a diagram for explaining the operation of the submarine optical communication system SYS2. As shown in Fig. 3, the submarine optical communication system SYS2 includes five terminal devices 1_1 to 1_5 as the multiple terminal devices 1, and three submarine devices 2_1 to 2_3 as the multiple submarine devices 2. The other configurations of the submarine optical communication system SYS2 are the same as those of the submarine optical communication system SYS1, and therefore description thereof will be omitted.

[0030] Similar to the submarine devices 2_1 to 2_2, the submarine device 2_3 is provided at a relay point (under the sea) of the submarine cable 3, and transmits, relays, and branches optical signals propagating through the submarine cable 3. In addition, the submarine devices 2_1 to 2_3 are configured to be able to switch the connection of four cores that constitute the multi-core fiber MCF1 included in the submarine cable 3.

[0031] Based on the monitoring results of the monitoring circuit 101, the control circuit 102 causes the submarine devices 2_1 to 2_3 to switch the connections of the four cores that make up the multi-core fiber MCF1.

[0032] More specifically, based on the monitoring results by the monitoring circuit 101, the control circuit 102 causes the submarine devices 2_1 to 2_3 to individually switch between the connection of the four cores C1a to C1d that constitute the multicore fiber MCF1_1 provided between the submarine devices 2_1 and 2_2, and the connection of the four cores (second partial cores) C2a to C2d that constitute the multicore fiber (second partial multicore fiber) MCF1_2 provided between the submarine devices 2_2 and 2_3.

[0033] For example, if the monitoring circuit 101 determines that core C1a, which is one of cores C1a to C1d that constitute the multicore fiber MCF1, which is provided between the submarine equipment 2_1 and the submarine equipment 2_2, is faulty, the control circuit 102 switches the transmission path of the optical signal that was being transmitted by core C1a to core C1d that transmits an optical signal with a lower priority than core C1a.

[0034] Furthermore, if the monitoring circuit 101 determines that core C2c, which is one of cores C2a to C2d that constitute the multicore fiber MCF1_2 that is provided between the submarine equipment 2_2 and the submarine equipment 2_3, is faulty, the control circuit 102 switches the transmission path of the optical signal that was being transmitted by core C2c to core C2d, which transmits an optical signal with a lower priority than core C2c.

[0035] In this way, the submarine optical communication system SYS2 according to the present embodiment can optimize communications even when a failure occurs in the submarine cable 3, without using a spare multicore fiber or a spare core, thereby reducing the costs associated with the spare multicore fiber and the spare core.

[0036] Furthermore, in the submarine optical communication system SYS2 according to this embodiment, for example, among the cores of the submarine cable 3 provided between the terminal equipment 1_1 and the terminal equipment 1_2, it is only necessary to switch the connection of only the core portion between two submarine devices where a fault has occurred to another core. Therefore, it is possible to prevent momentary disconnection of cores and multi-core fibers that are not faulty.

[0037] In the present embodiment, the control circuit 102 switches the connection of multiple cores constituting the multi-core fiber provided between the submarine device 2_1 and the submarine device 2_2 in the multi-core fiber MCF1, but this is not limiting. For example, the control circuit 102 may be configured to switch the connection of multiple cores constituting the multi-core fiber provided between the terminal device 1_1 and the submarine device 2_1 in the multi-core fiber MCF1.

[0038] <Third embodiment> Fig. 5 is a block diagram showing an example of the configuration of a submarine optical communication system SYS3 according to a third embodiment. Also, Figs. 6 to 10 are diagrams for explaining the operation of the submarine optical communication system SYS3. Note that Fig. 6 shows a part of the submarine optical communication system SYS3 before a failure occurs in the submarine cable, and Figs. 7 to 10 show a part of the submarine optical communication system SYS3 in a state where a failure occurs in the submarine cable.

[0039] 5, compared to the submarine optical communication system SYS2, the submarine optical communication system SYS3 includes a submarine cable 4 instead of the submarine cable 3. The other configurations of the submarine optical communication system SYS2 are the same as those of the submarine optical communication system SYS2, and therefore, description thereof will be omitted.

[0040] The submarine cable 4 includes a plurality of multi-core fibers. In this embodiment, as shown in Fig. 6, an example will be described in which the submarine cable 4 includes three multi-core fibers MCF1 to MCF3. Each of the multi-core fibers MCF1 to MCF3 is composed of four cores. However, each of the multi-core fibers MCF1 to MCF3 may be composed of any number of cores.

[0041] The submarine devices 2_1 to 2_3 are configured to be able to switch the connections of the four cores that make up each of the multi-core fibers MCF1 to MCF3. The submarine devices 2_1 to 2_3 are also configured to be able to switch the connections between the multi-core fibers MCF1 to MCF3.

[0042] The control circuit 102 causes the submarine devices 2_1 to 2_3 to switch the connections of the four cores constituting each of the multicore fibers MCF1 to MCF3 based on the monitoring results of the monitoring circuit 101. Alternatively, the control circuit 102 causes the submarine devices 2_1 to 2_3 to switch the connections between the multicore fibers MCF1 to MCF3 based on the monitoring results of the monitoring circuit 101.

[0043] 7, the monitoring circuit 101 determines that a core C1a, which is one of the cores C1a to C1d constituting the multi-core fiber MCF1_1 provided between the submarine device 2_1 and the submarine device 2_2, of the multi-core fiber MCF1, has failed. In this case, the control circuit 102 switches the transmission path of the optical signal transmitted by the core C1a to a core C3a that transmits an optical signal with a lower priority than the core C1a. Note that the core C3a is one of the cores C3a to C3d constituting the multi-core fiber MCF2_3 provided between the submarine device 2_1 and the submarine device 2_2 of the multi-core fiber MCF2.

[0044] In this way, the connection may be switched between one multi-core fiber and another multi-core fiber on a core-by-core basis.

[0045] 8 , the monitoring circuit 101 determines that a core C1a, which is one of the cores C1a to C1d constituting the multi-core fiber MCF1_1 provided between the submarine device 2_1 and the submarine device 2_2, has failed. In this case, the control circuit 102 switches the transmission path of the optical signal transmitted by the multi-core fiber MCF1_1 to a multi-core fiber MCF2_3 that transmits an optical signal with a lower priority than the multi-core fiber MCF1_1.

[0046] In this way, the connection may be switched between one multi-core fiber and another multi-core fiber on a multi-core fiber basis.

[0047] 9 , the monitoring circuit 101 determines that a core C1a, which is one of the cores C1a to C1d constituting the multi-core fiber MCF1_1 provided between the submarine device 2_1 and the submarine device 2_2, has failed. In this case, the control circuit 102 switches the transmission path of the optical signal transmitted by the multi-core fiber MCF1_1 to a multi-core fiber MCF2_3 that transmits an optical signal with a lower priority than the multi-core fiber MCF1_1.

[0048] 9, the monitoring circuit 101 determines that a fault has occurred in a core C5c, which is one of the cores C5a to C5d constituting a multicore fiber MCF3_5 provided between the submarine device 2_1 and the submarine device 2_2, of the multicore fiber MCF3. In this case, the control circuit 102 switches the transmission path of the optical signal transmitted by the core C5c to a core C5d that transmits an optical signal with a lower priority than that of the core C5c.

[0049] In this way, multiple signal transmission paths may be switched in response to multiple faults, respectively.

[0050] In addition, cores and multi-core fibers that are no longer in use due to switching of the signal transmission path may be used for transmitting optical signals supplied from the branch path. In the example of Fig. 10, core C6d, which is one of cores C6a to C6d constituting multi-core fiber MCF3_6 provided between the submarine device 2_2 and the submarine device 2_3 in the multi-core fiber MCF3, is used for transmitting optical signals supplied from the branch path.

[0051] In this way, the submarine optical communication system SYS3 according to the present embodiment can optimize communications even when a failure occurs in the submarine cable 4, without using a spare multicore fiber or a spare core, thereby reducing the costs associated with the spare multicore fiber and the spare core.

[0052] Furthermore, the submarine optical communication system SYS3 according to this embodiment only needs to switch the connection of only the core portion between two submarine devices where a fault has occurred to another core among the cores of the submarine cable 4 installed between the terminal equipment 1_1 and the terminal equipment 1_2. Alternatively, the submarine optical communication system SYS3 according to this embodiment only needs to switch the connection of only the multi-core fiber portion between two submarine devices where a fault has occurred to another multi-core fiber among the multi-core fibers of the submarine cable 4 installed between the terminal equipment 1_1 and the terminal equipment 1_2. This makes it possible to prevent momentary interruptions of cores and multi-core fibers where no fault has occurred.

[0053] In addition to the monitoring circuit 101 and the control circuit 102, the terminal device 1_1 may have a function of setting a priority for each multi-core fiber and a function of setting a priority for each of the multiple cores constituting each multi-core fiber. Hereinafter, this will be specifically described with reference to FIG. 11 .

[0054] 11 is a diagram showing an end station 1_1a, which is a modified example of the end station 1_1. The end station 1_1a further includes a priority setting circuit 103, as compared with the end station 1_1.

[0055] The priority setting circuit 103 sets a priority for each multi-core fiber included in the submarine cable 4, and sets a priority for each of the multiple cores that make up each multi-core fiber.

[0056] Here, the priority setting circuit 103 can individually set a priority for each multicore fiber provided between any two adjacent submarine devices and for each of the multiple cores constituting each multicore fiber. Similarly, the priority setting circuit 103 can individually set a priority for each multicore fiber provided between any adjacent terminal device and submarine device and for each of the multiple cores constituting each multicore fiber.

[0057] Furthermore, the priority setting circuit 103 may be configured to set different priorities depending on the time of day, such as morning, afternoon, or night, for each multi-core fiber provided between any two adjacent submarine devices and for each of the multiple cores constituting each multi-core fiber. Similarly, the priority setting circuit 103 may be configured to set different priorities depending on the time of day, for each multi-core fiber provided between any two adjacent terminal equipment and submarine devices and for each of the multiple cores constituting each multi-core fiber.

[0058] Furthermore, the priority setting circuit 103 may be configured to set a common priority for cores belonging to a first group among a plurality of cores constituting each multicore fiber provided between any two adjacent submarine equipment, and to set a common priority for cores belonging to a second group. Similarly, the priority setting circuit 103 may set a common priority for cores belonging to a first group among a plurality of cores constituting each multicore fiber provided between any adjacent terminal equipment and submarine equipment, and to set a common priority for cores belonging to a second group. The first group and the second group may, for example, be from different companies, etc.

[0059] Furthermore, the priority setting circuit 103 may be configured to set the highest priority to at least one core belonging to the first group and at least one core belonging to the second group among the multiple cores constituting each multicore fiber provided between any two adjacent submarine devices. Similarly, the priority setting circuit 103 may be configured to set the highest priority to at least one core belonging to the first group and at least one core belonging to the second group among the multiple cores constituting each multicore fiber provided between any adjacent terminal device and submarine device. This makes it possible to leave at least one core belonging to each group.

[0060] Furthermore, the priority setting circuit 103 may be configured to set priorities for cores belonging to the first group and cores belonging to the second group among the multiple cores constituting each multicore fiber provided between any two adjacent submarine equipment, such that the ratio between the numbers of cores is maintained. Similarly, the priority setting circuit 103 may be configured to set priorities for cores belonging to the first group and cores belonging to the second group among the multiple cores constituting each multicore fiber provided between any two adjacent terminal equipment and submarine equipment, such that the ratio between the numbers of cores is maintained.

[0061] For example, if there are six cores in the first group and three cores in the second group, and three of the cores fail, the ratio of cores in the first group to cores in the second group will be maintained, and the number of cores in the first group will be four and the number of cores in the second group will be two.

[0062] The embodiments of the present disclosure have been described in detail above with reference to the drawings, but the specific configurations are not limited to those described above, and various design changes and the like are possible within the scope that does not deviate from the gist of the present disclosure.

[0063] In the above-described embodiment, the present disclosure has been described as a hardware configuration, but the present disclosure is not limited to this. The present disclosure can also be realized by having a CPU (Central Processing Unit) execute a computer program to perform part or all of the control processing in the submarine optical communication system SYS1.

[0064] The above-described program includes a set of instructions (or software code) that, when loaded into a computer, causes the computer to perform one or more functions described in the embodiments. The program may be stored on a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, computer-readable media or tangible storage media include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drives (SSDs) or other memory technologies, CD-ROMs, digital versatile discs (DVDs), Blu-ray discs or other optical disk storage, magnetic cassettes, magnetic tapes, magnetic disk storage, or other magnetic storage devices. The program may also be transmitted on a transitory computer-readable medium or a communication medium. By way of example and not limitation, transitory computer-readable media or communication media include electrical, optical, acoustic, or other forms of transmission signals.

[0065] A part or all of the above-described embodiments can be described as, but not limited to, the following supplementary notes.

[0066] (Supplementary Note 1) A submarine optical communication system comprising: a plurality of terminal devices; a first multi-core fiber constituted by a plurality of first cores that transmits an optical signal used for communication between the plurality of terminal devices; and first and second submarine equipment that are provided at relay points of the first multi-core fiber and configured to be able to switch the connection of the plurality of first cores that constitute the first multi-core fiber, wherein at least one of the plurality of terminal devices comprises: a monitoring circuit that monitors a signal transmission status of the first multi-core fiber; and a control circuit that, when it is determined by the monitoring circuit that one of the plurality of first partial cores that constitutes a first partial multi-core fiber of the first multi-core fiber that is provided between the first submarine equipment and the second submarine equipment has failed, switches the transmission path of the optical signal that has been transmitted by the first partial core that has been determined to be failed to another first partial core that transmits an optical signal that has a lower priority than the first partial core that has been determined to be failed.

[0067] (Supplementary Note 2) The submarine optical communication system according to Supplementary Note 1, wherein at least one of the plurality of terminal devices further comprises a priority setting circuit that sets a priority of an optical signal to be transmitted for each of a plurality of first cores that constitute the first multicore fiber.

[0068] (Supplementary Note 3) The submarine optical communication system according to Supplementary Note 2, wherein the priority setting circuit sets different priorities for each of the plurality of first cores constituting the first multicore fiber depending on the time period.

[0069] (Supplementary Note 4) The submarine optical communication system according to Supplementary Note 2, wherein the priority setting circuit sets a common priority for first cores belonging to a first group among the plurality of first cores constituting the first multicore fiber, and sets a common priority for first cores belonging to a second group.

[0070] (Supplementary Note 5) The submarine optical communication system according to Supplementary Note 2, wherein the priority setting circuit sets the highest priority to at least one of the first cores belonging to a first group and at least one of the first cores belonging to a second group among the plurality of first cores constituting the first multicore fiber.

[0071] (Supplementary Note 6) The submarine optical communication system according to Supplementary Note 2, wherein the priority setting circuit sets priorities for each of the first cores belonging to a first group and the first cores belonging to a second group among the plurality of first cores constituting the first multicore fiber, such that a ratio between the number of first cores belonging to the first group and the number of first cores belonging to the second group is maintained.

[0072] (Supplementary Note 7) The submarine optical communication system according to Supplementary Note 1, further comprising a third submarine device provided at a relay point of the first multicore fiber and configured to be able to switch connections of a plurality of first cores constituting the first multicore fiber, wherein when the monitoring circuit determines that any of a plurality of second partial cores constituting a second partial multicore fiber of the first multicore fiber provided between the second submarine device and the third submarine device has failed, the control circuit switches the transmission path of the optical signal transmitted by the second partial core determined to be failed to another second partial core that transmits an optical signal of a lower priority than the second partial core determined to be failed.

[0073] (Supplementary Note 8) The submarine optical communication system according to Supplementary Note 7, wherein at least one of the plurality of terminal devices further comprises a priority setting circuit that sets a priority of an optical signal to be transmitted for each of a plurality of first cores that constitute the first multicore fiber, and the priority setting circuit sets a priority for each of a plurality of first partial cores that constitute a first partial multicore fiber of the first multicore fiber provided between the first submarine equipment and the second submarine equipment, and also sets a priority for each of a plurality of second partial cores that constitute a second partial multicore fiber of the first multicore fiber provided between the second submarine equipment and the third submarine equipment.

[0074] (Supplementary Note 9) The submarine optical communication system according to Supplementary Note 1, further comprising a second multicore fiber constituted by a plurality of second cores that transmits optical signals used for communication between the plurality of terminal equipment, wherein the first submarine equipment and the second submarine equipment are further configured to be able to switch the connection of the plurality of second cores that constitute the second multicore fiber, and wherein in at least one of the plurality of terminal equipment, the monitoring circuit further monitors the signal transmission status of the second multicore fiber, and when the monitoring circuit determines that any of the plurality of third partial cores that constitute a third partial multicore fiber of the second multicore fiber provided between the first submarine equipment and the second submarine equipment is faulty, the control circuit switches the transmission path of the optical signal that has been transmitted by the third partial core determined to be faulty to another third partial core that transmits an optical signal of lower priority than the third partial core determined to be faulty.

[0075] (Supplementary Note 10) The submarine optical communication system according to Supplementary Note 9, wherein at least one of the plurality of terminal devices further comprises a priority setting circuit that sets priorities of optical signals to be transmitted for each of a plurality of first cores that constitute the first multicore fiber and for each of a plurality of second cores that constitute the second multicore fiber.

[0076] (Supplementary Note 11) The submarine optical communication system according to Supplementary Note 10, wherein the priority setting circuit sets different priorities depending on time periods for each of a plurality of first cores constituting the first multicore fiber and each of a plurality of second cores constituting the second multicore fiber.

[0077] (Supplementary Note 12) The submarine optical communication system according to Supplementary Note 10, wherein the priority setting circuit sets a common priority for first cores belonging to a first group among the plurality of first cores constituting the first multicore fiber, sets a common priority for first cores belonging to a second group, and sets a common priority for second cores belonging to a third group among the plurality of second cores constituting the second multicore fiber, and sets a common priority for second cores belonging to a fourth group.

[0078] (Supplementary Note 13) The submarine optical communication system according to Supplementary Note 10, wherein the priority setting circuit sets the highest priority to at least one first core belonging to a first group and at least one first core belonging to a second group among the plurality of first cores constituting the first multicore fiber, and also sets the highest priority to at least one second core belonging to a third group and at least one second core belonging to a fourth group among the plurality of second cores constituting the second multicore fiber.

[0079] (Supplementary Note 14) The submarine optical communication system according to Supplementary Note 10, wherein the priority setting circuit sets priorities for each of the first cores belonging to a first group and each of the first cores belonging to a second group among the plurality of first cores constituting the first multicore fiber, such that a ratio between the number of first cores belonging to the first group and the number of first cores belonging to the second group is maintained, and sets priorities for each of the second cores belonging to a third group and each of the second cores belonging to a fourth group among the plurality of second cores constituting the second multicore fiber, such that a ratio between the number of second cores belonging to the third group and the number of second cores belonging to the fourth group is maintained.

[0080] (Supplementary Note 15) In at least one of the plurality of terminal devices, when the monitoring circuit determines that any one of the plurality of first partial cores constituting a first partial multicore fiber provided between the first submarine equipment and the second submarine equipment in the first multicore fiber has failed, the control circuit switches the transmission path of the optical signal transmitted by the first partial core determined to have failed to another first partial core transmitting an optical signal having a lower priority than the first partial core determined to have failed, or any one of the plurality of third partial cores constituting the third partial multicore fiber; and when the monitoring circuit determines that any one of the plurality of third partial cores constituting the third partial multicore fiber in the second multicore fiber has failed, the control circuit switches the transmission path of the optical signal transmitted by the third partial core determined to have failed to another third partial core transmitting an optical signal having a lower priority than the third partial core determined to have failed, or any one of the plurality of first partial cores constituting the first partial multicore fiber. 10. The undersea optical communication system of claim 9.

[0081] (Supplementary Note 16) The present invention further comprises a third submarine device that is provided at a relay point of the first and second multicore fibers and is configured to be able to switch a connection of a plurality of first cores that constitute the first multicore fiber and a connection of a plurality of second cores that constitute the second multicore fiber, wherein the control circuit, when it is determined by the monitoring circuit that any of a plurality of second partial cores that constitute a second partial multicore fiber of the first multicore fiber provided between the second submarine device and the third submarine device has failed, switches the transmission path of the optical signal that has been transmitted by the second partial core that has been determined to be failed to another second partial core that transmits an optical signal having a lower priority than the second partial core that has been determined to be failed, and when it is determined by the monitoring circuit that any of a plurality of fourth partial cores that constitute a fourth partial multicore fiber of the second multicore fiber provided between the second submarine device and the third submarine device has failed, switches the transmission path of the optical signal that has been transmitted by the fourth partial core that has been determined to be failed to another fourth partial core that transmits an optical signal having a lower priority than the fourth partial core that has been determined to be failed. 10. The undersea optical communication system of claim 9.

[0082] (Supplementary Note 17) In at least one of the plurality of terminal devices, when the monitoring circuit determines that any one of a plurality of first partial cores constituting a first partial multicore fiber provided between the first submarine equipment and the second submarine equipment in the first multicore fiber has failed, the control circuit switches a transmission path of an optical signal transmitted by the first partial core determined to have failed to another first partial core transmitting an optical signal having a lower priority than the first partial core determined to have failed, or any one of a plurality of third partial cores constituting the third partial multicore fiber; when the monitoring circuit determines that any one of a plurality of third partial cores constituting the third partial multicore fiber in the second multicore fiber has failed, the control circuit switches a transmission path of an optical signal transmitted by the third partial core determined to have failed to another third partial core transmitting an optical signal having a lower priority than the third partial core determined to have failed, or any one of a plurality of first partial cores constituting the first partial multicore fiber; the monitoring circuit determines whether any one of the plurality of second partial cores constituting a second partial multicore fiber of the first multicore fiber, the second partial core being determined to be faulty, is faulty, the monitoring circuit switches the transmission path of the optical signal transmitted by the second partial core determined to be faulty to another second partial core transmitting an optical signal having a lower priority than the second partial core determined to be faulty, or to any one of the plurality of fourth partial cores constituting the fourth partial multicore fiber; and the monitoring circuit determines whether any one of the plurality of fourth partial cores constituting the fourth partial multicore fiber of the second multicore fiber, the fourth partial core being faulty, is faulty, the monitoring circuit switches the transmission path of the optical signal transmitted by the fourth partial core determined to be faulty to another fourth partial core transmitting an optical signal having a lower priority than the fourth partial core determined to be faulty, or to any one of the plurality of second partial cores constituting the second partial multicore fiber.

[0083] (Supplementary Note 18) A control method for a submarine optical communication system comprising: a plurality of terminal devices; a first multi-core fiber constituted by a plurality of first cores that transmits an optical signal used for communication between the plurality of terminal devices; and first and second submarine equipment that are provided at relay points of the first multi-core fiber and are configured to be able to switch a connection of the plurality of first cores that constitute the first multi-core fiber, the control method comprising: using at least one of the plurality of terminal devices to monitor a signal transmission status of the first multi-core fiber; and, when it is determined that any of a plurality of first partial cores that constitute a first partial multi-core fiber of the first multi-core fiber that is provided between the first submarine equipment and the second submarine equipment has failed, switching the transmission path of the optical signal that has been transmitted by the first partial core determined to be failed to another first partial core that transmits an optical signal that has a lower priority than the first partial core determined to be failed.

[0084] (Supplementary Note 19) A non-transitory computer-readable medium storing a control program that causes a computer to execute control processes in a submarine optical communication system including: a plurality of terminal devices; a first multi-core fiber composed of a plurality of first cores that transmits optical signals used for communication between the plurality of terminal devices; and first and second submarine equipment that are provided at relay points of the first multi-core fiber and are configured to be able to switch the connection of the plurality of first cores that constitute the first multi-core fiber, the non-transitory computer-readable medium storing a control program that causes a computer to execute the following processes: monitoring a signal transmission status of the first multi-core fiber using at least one of the plurality of terminal devices; and, when it is determined that any of a plurality of first partial cores that constitute a first partial multi-core fiber provided between the first submarine equipment and the second submarine equipment is faulty, switching the transmission path of the optical signal that has been transmitted by the first partial core determined to be faulty to another first partial core that transmits an optical signal that has a lower priority than the first partial core determined to be faulty.

[0085] (Supplementary Note 20) A system comprising: a plurality of terminal devices; a first multicore fiber composed of a plurality of first cores, transmitting an optical signal used in communication between the plurality of terminal devices; a second multicore fiber composed of a plurality of second cores, transmitting an optical signal used in communication between the plurality of terminal devices; a third multicore fiber composed of a plurality of third cores, transmitting an optical signal used in communication between the plurality of terminal devices; and first and second submarine devices, provided at relay points of the first to third multicore fibers and configured to be able to switch connections of the first to third multicore fibers, wherein at least one of the plurality of terminal devices has: a monitoring circuit that monitors signal transmission states of first to third partial multicore fibers provided between the first submarine device and the second submarine device out of the first to third multicore fibers; and a control circuit, a submarine optical communication system, wherein, when the monitoring circuit determines that any one of a plurality of first partial cores constituting the first partial multicore fiber has failed, the transmission path of the optical signal transmitted by the first partial multicore fiber is switched to the second partial multicore fiber or the third partial multicore fiber that transmits an optical signal having a lower priority than the first partial multicore fiber; when the monitoring circuit determines that any one of the plurality of second partial cores constituting the second partial multicore fiber has failed, the transmission path of the optical signal transmitted by the second partial multicore fiber is switched to the first partial multicore fiber or the third partial multicore fiber that transmits an optical signal having a lower priority than the second partial multicore fiber; and when the monitoring circuit determines that any one of a plurality of third partial cores constituting the third partial multicore fiber has failed, the transmission path of the optical signal transmitted by the third partial multicore fiber is switched to the first partial multicore fiber or the second partial multicore fiber that transmits an optical signal having a lower priority than the third partial multicore fiber.

[0086] Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the invention.

[0087] SYS1: Submarine optical communication system SYS2: Submarine optical communication system SYS3: Submarine optical communication system 1, 1_1 to 1_5: Terminal equipment 2, 2_1 to 2_3: Submarine equipment 3: Submarine cable 4: Submarine cable 101: Monitoring circuit 102: Control circuit 103: Priority setting circuit

Claims

1. a plurality of terminal devices; a first multi-core fiber configured by a plurality of first cores, which transmits an optical signal used for communication between the plurality of terminal devices; a first submarine device and a second submarine device that are provided at a relay point of the first multicore fiber and configured to be able to switch connections of a plurality of first cores that constitute the first multicore fiber; Equipped with At least one of the plurality of terminal devices a monitoring circuit for monitoring a signal transmission status of the first multicore fiber; a control circuit that, when it is determined by the monitoring circuit that any one of a plurality of first partial cores constituting a first partial multicore fiber of the first multicore fiber provided between the first submarine equipment and the second submarine equipment has failed, switches a transmission path of an optical signal transmitted by the first partial core determined to have failed to another first partial core that transmits an optical signal having a lower priority than the first partial core determined to have failed; An undersea optical communication system comprising:

2. At least one of the plurality of terminal devices further comprising a priority setting circuit that sets a priority of an optical signal to be transmitted for each of a plurality of first cores that constitute the first multicore fiber; 2. The undersea optical communication system according to claim 1.

3. the priority setting circuit sets different priorities for each of the plurality of first cores constituting the first multicore fiber depending on the time period; 3. The undersea optical communication system according to claim 2.

4. the priority setting circuit sets a common priority for first cores belonging to a first group among the plurality of first cores constituting the first multicore fiber, and sets a common priority for first cores belonging to a second group; 3. The undersea optical communication system according to claim 2.

5. the priority setting circuit sets the highest priority to at least one of the first cores belonging to a first group and at least one of the first cores belonging to a second group among the plurality of first cores constituting the first multicore fiber; 3. The undersea optical communication system according to claim 2.

6. the priority setting circuit sets priorities for the first cores belonging to a first group and the first cores belonging to a second group among the plurality of first cores constituting the first multicore fiber, such that a ratio between the number of first cores belonging to the first group and the number of first cores belonging to the second group is maintained.

3. The undersea optical communication system according to claim 2.

7. a third submarine device that is provided at a relay point of the first multicore fiber and is configured to be able to switch connections of a plurality of first cores that constitute the first multicore fiber; when the monitoring circuit determines that any one of a plurality of second partial cores constituting a second partial multicore fiber of the first multicore fiber provided between the second submarine equipment and the third submarine equipment has failed, the control circuit switches the transmission path of the optical signal transmitted by the second partial core determined to be failed to another second partial core transmitting an optical signal having a lower priority than the second partial core determined to be failed.

2. The undersea optical communication system according to claim 1.

8. At least one of the plurality of terminal devices further comprising a priority setting circuit that sets a priority of an optical signal to be transmitted for each of a plurality of first cores that constitute the first multicore fiber; The priority setting circuit a priority is set for each of a plurality of first partial cores constituting a first partial multicore fiber provided between the first submarine device and the second submarine device in the first multicore fiber, and a priority is set for each of a plurality of second partial cores constituting a second partial multicore fiber provided between the second submarine device and the third submarine device in the first multicore fiber; 8. The undersea optical communication system according to claim 7.

9. a plurality of terminal devices; a first multi-core fiber configured by a plurality of first cores, which transmits an optical signal used for communication between the plurality of terminal devices; a first submarine device and a second submarine device that are provided at a relay point of the first multicore fiber and configured to be able to switch connections of a plurality of first cores that constitute the first multicore fiber; A control method for a submarine optical communication system comprising: monitoring a signal transmission status of the first multicore fiber using at least one of the plurality of terminal devices; when it is determined that any one of a plurality of first partial cores constituting a first partial multicore fiber of the first multicore fiber provided between the first submarine equipment and the second submarine equipment has failed, switching the transmission path of the optical signal transmitted by the first partial core determined to have failed to another first partial core transmitting an optical signal having a lower priority than that of the first partial core determined to have failed; A method for controlling an undersea optical communication system.

10. a plurality of terminal devices; a first multi-core fiber configured by a plurality of first cores, which transmits an optical signal used for communication between the plurality of terminal devices; a first submarine device and a second submarine device that are provided at a relay point of the first multicore fiber and configured to be able to switch connections of a plurality of first cores that constitute the first multicore fiber; A control program for causing a computer to execute control processing in a submarine optical communication system comprising: a process of monitoring a signal transmission status of the first multicore fiber using at least one of the plurality of terminal devices; a process of switching a transmission path of an optical signal transmitted by the first partial core determined to be faulty to another first partial core transmitting an optical signal having a lower priority than the first partial core determined to be faulty, when it is determined that any of a plurality of first partial cores constituting a first partial multicore fiber of the first multicore fiber provided between the first submarine equipment and the second submarine equipment has failed; A control program that causes a computer to execute the above.