How to switch core wires

Abstract

The purpose of the present invention is to provide a core wire switching method that, in an optical communication system, can shorten switching work time even when there is a demand fluctuation in which branch and leaf optical transmission paths change, and allows timely core wire switching.　An optical communication system 302 has a structure comprising a backbone optical transmission path 12, and a plurality of branch and leaf optical transmission paths 17 each having one end connected thereto, wherein at least one optical fiber core wire 51 in the backbone optical transmission path 12 is disposed so as to fold back at the other end thereof in at least two branch and leaf optical transmission paths 17. When optical communication is necessary between the branch and leaf optical transmission paths 17 and the outside, the optical fiber core wire 51 in the branch and leaf optical transmission path 17 is disconnected, a lead-out optical fiber 18 is connected to a disconnected part on the desired side of the disconnected optical fiber core wire 51, and a lead-out connection is formed. When optical communication becomes unnecessary between the branch and leaf optical transmission path and the outside, the lead-out connection is released, and the disconnected parts of the disconnected optical fiber core wire in the branch and leaf optical transmission path are re-connected.

Description

[Technical Field]

[0001] The present disclosure relates to a method for switching optical fiber cores in an optical transmission line. [Background technology]

[0002] FIG. 1 is a diagram illustrating a currently used method for switching optical fiber cores. An optical communication system 301 includes a trunk optical transmission line 12 and a plurality of branch optical transmission lines (17-1, 17-2) connected at one end to the trunk optical transmission line 12. In the optical communication system 301, as shown in FIG. 1, the trunk optical transmission line 12 may be a loop optical cable and the branch optical transmission lines (17-1, 17-2) may be star optical cables. A resident station 10 is connected to the trunk optical transmission line 12. The trunk optical transmission line 12 and the branch optical transmission lines (17-1, 17-2) are connected within underground manholes (15-1, 15-2). The number of branch optical transmission lines 17 is not limited to two. There may be one, or three or more.

[0003] 1(A) shows the communication state at the initial stage. A using terminal 20-1 is located near the branch optical transmission line 17-1, and the branch optical transmission line 17-1 and the using terminal 20-1 are connected by an extracted optical fiber (drop optical fiber) 18. The communication path at the initial stage is shown by a dotted line. The using terminal is, for example, a base station.

[0004] 1(B) shows the communication state after switching from using terminal 20-1 to using terminal 20-2 due to a change in communication demand. Using terminal 20-2 is located near branch optical transmission line 17-2, and branch optical transmission line 17-2 and using terminal 20-2 are connected by drawn optical fiber (drop optical fiber) 18. The communication path after switching is shown by a dotted line.

[0005] 2 is a diagram illustrating a connection point between the branch optical transmission line 17 and the drawn optical fiber 18. The branch optical transmission line 17 includes a plurality of optical fiber core wires 50. A connection point is provided in the branch optical transmission line 17 near the use terminal 20, and a desired optical fiber core wire 50 is cut out of the optical fiber core wires 50 present in the branch optical transmission line 17 ("X" indicates a cutting point 22). Then, one end of the drawn optical fiber 18 is connected to the desired cut end of the cut optical fiber core wire 50 ("◯" indicates a connection point 21). Through this connection point, an optical signal propagating through the desired optical fiber core wire 50 in the branch optical transmission line 17 is output to the use terminal 20, and an optical signal from the use terminal 20 is output to the desired optical fiber core wire 50 in the branch optical transmission line 17.

[0006] 3A and 3B are diagrams illustrating the construction work when changing from the use terminal 20-1 (FIG. 3A) connected to the branch optical transmission line 17-1 to the use terminal 20-2 (FIG. 3B) connected to the branch optical transmission line 17-2, as described in FIG. 1. Assume that the trunk optical transmission line 12 includes eight optical fiber core wires 51. In the initial stage of FIG. 3A, four of the optical fiber core wires 51 (optical fiber core wires 51-1 to 51-4) in the trunk optical transmission line 12 are cut in the manhole 15-1 and connected to four optical fiber core wires 50 (optical fiber core wires 50-1 to 50-4) in the branch optical transmission line 17-1, respectively. Similarly, four of the optical fiber core wires 51 (optical fiber core wires 51-5 to 51-8) in the trunk optical transmission line 12 are cut in the manhole 15-2 and connected to four optical fiber core wires 50 (optical fiber core wires 50-5 to 50-8) in the branch optical transmission line 17-2, respectively. The exchange 10 and the user terminal 20-1 can communicate with each other via the optical fiber core 51-1 in the trunk optical transmission line 12 and the optical fiber core 50-1 in the branch optical transmission line 17-1.

[0007] As mentioned above, a change in the use terminal 20, which changes the branch optical transmission line 17, may occur due to a change in demand. In such a case (for example, when changing from use terminal 20-1 to use terminal 20-2), switching work is performed in two manholes (15-1 and 15-2) as shown in FIG. 3(B). First, in manhole 15-1, the connection between the optical fiber 51-1 and the optical fiber 50-1 is terminated, and the optical fiber 51-1 is connected to the optical fiber 51-1 of the trunk optical transmission line 12 between manholes 15-1 and 15-2. Furthermore, in manhole 15-2, the connection between the optical fiber 51-8 and the optical fiber 50-8 is terminated, and the optical fiber 51-1 is cut. Then, the optical fiber 51-1 is connected to the optical fiber 50-8. [Prior art documents] [Non-patent literature]

[0008] [Non-Patent Document 1] NTT Research and Development, "Optical wiring method for optical access systems" (https: / / www.rd.ntt / as / history / media / me0403.html), retrieved December 9, 2022 [Non-patent document 2] NTT Research and Development, "Optical Fiber Cable Technology" (https: / / www.rd.ntt / as / history / media / me01.html), retrieved December 9, 2022 Summary of the Invention [Problem to be solved by the invention]

[0009] As mentioned above, when there is a demand fluctuation that changes the branch optical transmission line 17, it is necessary to carry out switching work at each manhole 15. Switching work at an underground manhole takes a long time, and there is a problem that it is difficult to switch the core wires in a timely manner.

[0010] Therefore, in order to solve the above-mentioned problems, the present invention aims to provide a core cable switching method that shortens the switching work time and enables timely core cable switching even when there is a demand fluctuation that changes the branch optical transmission path. [Means for solving the problem]

[0011] In order to achieve the above object, the core fiber switching method of the present invention arranges the optical fiber core wire so that it is folded back at the far end of the branch optical transmission line, and connects the optical fiber core wire of the branch optical transmission line to the optical fiber core wire of the trunk optical transmission line so that the optical signal first leaves the trunk optical transmission line, travels back and forth along the branch optical transmission line, and then returns.

[0012] Specifically, the fiber switching method according to the present invention is a fiber switching method in an optical communication system, comprising: The optical communication system includes a trunk optical transmission line and a plurality of branch optical transmission lines each having one end connected to the trunk optical transmission line, and at least one optical fiber core in the trunk optical transmission line is arranged in at least two of the branch optical transmission lines so as to be folded back at the other end of the branch optical transmission line, When optical communication between the branch optical transmission line and the outside becomes necessary, the optical fiber core wire in the branch optical transmission line is cut, and the drawn optical fiber from the branch optical transmission line to the outside is connected to the cut part on the desired side of the cut optical fiber core wire, thereby forming a drawn connection; When optical communication between the branch optical transmission line and the outside becomes unnecessary, the drawing connection is released and the cut portions of the optical fiber core wires that have been cut in the branch optical transmission line are reconnected. It is characterized by:

[0013] Furthermore, the optical fiber switching method according to the present invention is characterized in that the branch optical transmission line that constitutes the draw-out connection and the branch optical transmission line that releases the draw-out connection are not the same.

[0014] By wiring the optical fiber core wires in this manner, even if there is a demand fluctuation that changes the branch optical transmission line, the work can be completed in a short time by simply connecting and disconnecting the lead-out of the branch optical transmission line without performing switching work inside a manhole.In other words, the present invention can provide a core wire switching method that shortens the switching work time even if there is a demand fluctuation that changes the branch optical transmission line, and enables timely core wire switching.

[0015] In the fiber switching method according to the present invention, there may be another optical fiber fiber in the trunk optical transmission line of the optical communication system that does not pass through the branch optical transmission line.

[0016] In the optical fiber switching method according to the present invention, the trunk optical transmission line may be a loop type having a start point and a finish point at the same accommodation station. Also, in the optical fiber switching method according to the present invention, the connection point between the trunk optical transmission line and the branch optical transmission line may be located at any place, such as underground or inside a building.

[0017] The above inventions can be combined as much as possible. [Effects of the Invention]

[0018] The present invention can provide a core fiber switching method that can shorten the switching work time and switch core fibers in a timely manner even when there is a demand fluctuation that changes the branch optical transmission line. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a diagram illustrating a configuration of an optical communication system. [Figure 2] FIG. 1 is a diagram illustrating an extraction connection using an extraction optical fiber (drop optical fiber). [Figure 3] FIG. 10 is a diagram illustrating the core wire switching work. [Figure 4] 1 is a diagram illustrating an optical communication system in which a fiber switching method according to the present invention can be implemented; [Figure 5]1A to 1C are diagrams illustrating key points of a fiber switching method according to the present invention. [Figure 6] 1A to 1C are diagrams illustrating key points of a fiber switching method according to the present invention. [Figure 7] 1 is a diagram illustrating an optical communication system in which a fiber switching method according to the present invention can be implemented; [Figure 8] 1A to 1C are diagrams illustrating a method for switching core fibers according to the present invention. [Figure 9] 1A to 1C are diagrams illustrating a method for switching core fibers according to the present invention. [Figure 10] 1A to 1C are diagrams illustrating a method for switching core fibers according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] The following description of the preferred embodiments of the present invention will be given with reference to the accompanying drawings. The preferred embodiments described below are examples of the present invention, and the present invention is not limited to the preferred embodiments. In this specification and the drawings, components having the same reference numerals are intended to represent the same components.

[0021] 4 is a diagram illustrating an optical communication system 302 capable of implementing the fiber switching method of this embodiment. The optical communication system 302 includes a trunk optical transmission line 12 and a plurality of branch optical transmission lines (17-1, 17-2) each having one end connected to the trunk optical transmission line 12, and is configured such that at least one optical fiber 51 in the trunk optical transmission line 12 is arranged in at least two branch optical transmission lines (17-1, 17-2) so as to be folded back at the other end of the branch optical transmission line (17-1, 17-2).

[0022] In this embodiment, the trunk optical transmission line 12 is a loop type having the same accommodating station 10 as its start point and end point. However, the present invention is not limited to a loop type trunk optical transmission line. Furthermore, in this embodiment, the connection points between the trunk optical transmission line 12 and the branch optical transmission lines (17-1, 17-2) are located in underground manholes (15-1, 15-2). However, the present invention is not limited to the connection points being located inside manholes. The connection points may be located anywhere, such as inside a building. Furthermore, although FIG. 4 shows two branch optical transmission lines, the present invention is not limited to two branch optical transmission lines.

[0023] 5 is a diagram illustrating the first point of the present invention. It is a diagram of the other end P1 (the farthest point not connected to the trunk optical transmission line 12) of the branch optical transmission line (17-1, 17-2). At the other end P1 of the branch optical transmission line (17-1, 17-2), the optical fiber core 51 is arranged so as to be folded back. The optical fiber core 51 travels from the connection point between the trunk optical transmission line 12 and the branch optical transmission line (17-1, 17-2) via the other end P1, and then travels back and forth to the connection point again.

[0024] 6 is a diagram illustrating the second point of the present invention. A connection point P2 is configured so that the optical fiber 51 in the trunk optical transmission line 12 is pulled out from the manholes (15-1, 15-2) to the branch optical transmission lines (17-1, 17-2). With this configuration, the optical signal propagating through the optical fiber 51 in the trunk optical transmission line 12 travels back and forth through each branch optical transmission line (17-1, 17-2).

[0025] FIG. 7 is a diagram illustrating the optical communication system 302 in more detail. When switching core cables across the branch optical transmission line from the use terminal 20-1 of the branch optical transmission line 17-1 to the use terminal 20-2 of the branch optical transmission line 17-2, the optical communication system 302 makes it possible to switch core cables without performing construction work inside the manholes (15-1, 15-2) by using point 1 in Fig. 5 and point 2 in Fig. 6. Specifically, core cables 1 to 4 of the branch optical transmission line 17-1 are pre-connected to the trunk optical transmission line 12 and the branch optical transmission line 17-2, and are available for use regardless of the optical transmission line.

[0026] Note that there may be a certain number of core fibers in each branch optical transmission line 17 that cannot be switched across the branch optical transmission line without folding back. That is, in the optical communication system 302, there may be other optical fiber core fibers in the backbone optical transmission line 12 that do not pass through the branch optical transmission line 17.

[0027] 8 to 10 are diagrams illustrating a core line switching method in the optical communication system 302. In the optical communication system 302, the optical fiber core lines of each branch optical transmission line 17 are in a state where they can be reassigned via the trunk optical transmission line 12, so core line switching is performed as follows. Fig. 8 shows the state before core line switching. Fig. 9 shows the state during core line switching. Fig. 10 shows the state after core line switching.

[0028] (Step 1) When optical communication is required between the branch optical transmission line 17 and the outside (terminal 20), the optical fiber core 51 in the branch optical transmission line 17 is cut, and the drawn optical fiber 18 extending from the branch optical transmission line 17 to the outside is connected to the cut part on the desired side of the cut optical fiber core 51, thereby forming a drawn connection. 8, optical communication is required between the branch optical transmission line 17-1 and the use terminal 20-1, so the optical fiber core 51 (core No. 1) in the branch optical transmission line 17-1 is cut (reference numeral 22), and the drawn optical fiber 18 is connected (reference numeral 21) to the cut part of the cut optical fiber core 51 (core No. 1) on the desired side (the trunk optical transmission line 12 side) to form a drawn connection. The same applies between the branch optical transmission line 17-2 and the use terminal 20-2.

[0029] (Step 2) When optical communication between the branch optical transmission line and the outside becomes unnecessary, the drawing connection is released and the cut portions of the optical fiber core wires that have been cut within the branch optical transmission line are reconnected. First, as shown in Fig. 9, the connection between the drawn optical fiber 18 and the branch optical transmission line 17-1 is released. The state between the branch optical transmission line 17-2 and the use terminal 20-2 is maintained as shown in Fig. 8. Next, as shown in Fig. 10, the first optical fiber core 51 of the branch optical transmission line 17-1 is connected (reference numeral 21), and the cut portion 22 is removed.

[0030] (Effects of the Invention) The optical communication system 302 and the fiber switching method of the present invention provide the following advantages. (1) In order to increase the resistance to demand fluctuations in star-type wiring, the optical fiber core wires are folded back at the end of the star-type wiring (the other end of the branch optical transmission line), making it possible to interchange the core wires by treating the star-type wiring as a loop-type wiring. (2) When a demand fluctuation occurs across a star-shaped distribution (branch optical transmission line), the time required for construction work such as fiber switching in underground manholes can be reduced or eliminated. In addition, fiber switching across a star-shaped distribution (branch optical transmission line) can be achieved in a timely manner at any time. (3) When switching the fiber from one branch optical transmission line to another, work inside a manhole is no longer necessary, reducing the need for repeated construction and construction costs. Rapid fiber switching across star-shaped wiring (branch optical transmission lines) is possible.

[0031] Note that various types of optical fiber cores can be applied to the optical fiber cores contained in the trunk optical transmission lines, branch optical transmission lines, loop cables, and star cables described in this embodiment, regardless of their types or categories. [Explanation of symbols]

[0032] 10: Storage station 12: Backbone optical transmission line 15, 15-1, 15-2: Manhole 17, 17-1, 17-2: Branch optical transmission line 18: Extracted optical fiber 20, 20-1, 20-2: Device used 21: Connection point 22: Cutting section 50, 51: Optical fiber core 301, 302: Optical communication systems

Claims

1. A fiber switching method in an optical communication system, comprising: The optical communication system comprises a trunk optical transmission line and a plurality of branch optical transmission lines, one end of which is connected to the trunk optical transmission line at each connection point, and at least two of the branch optical transmission lines are configured so that at least one optical fiber core in the trunk optical transmission line is drawn out from each connection point, folded back at the other end of each of the branch optical transmission lines, and returned from the connection point into the trunk optical transmission line, When optical communication between the branch optical transmission line and the outside becomes necessary, the optical fiber core wire in the branch optical transmission line is cut, and the drawn optical fiber from the branch optical transmission line to the outside is connected to the cut part on the desired side of the cut optical fiber core wire, thereby forming a drawn connection; When optical communication between the branch optical transmission line and the outside becomes unnecessary, the drawing connection is released and the cut portions of the optical fiber core wires that have been cut in the branch optical transmission line are reconnected. A core switching method characterized by the above.

2. 2. The fiber switching method according to claim 1, wherein the branch optical transmission line that constitutes the lead connection and the branch optical transmission line that releases the lead connection are not the same.

3. 2. The fiber switching method according to claim 1, wherein another optical fiber fiber that does not pass through the branch optical transmission line is present in the trunk optical transmission line of the optical communication system.

4. 2. The fiber switching method according to claim 1, wherein the trunk optical transmission line is a loop type having the same accommodating station as a start point and a finish point.

5. A method for switching core wires as described in claim 1, characterized in that the connection point is located underground.

Images