Optical transmission device and optical transmission method

Abstract

This optical transmission device transmits an optical signal between a communication terminal device and a network without converting the optical signal into an electric signal. The optical transmission device comprises: a plurality of splitter / combiners for the input / output of optical signals between the optical transmission device and the communication terminal device connected thereto; a plurality of wavelength demultiplexers for the input / output of optical signals between the optical transmission device and a network connected thereto; an uplink signal splitter that outputs uplink optical signals output from the splitter / combiners to an electric processing unit that performs a predetermined electric process on the optical signals; and an uplink signal combiner that outputs the uplink optical signals that have been subjected to the electric process by the electric processing unit to predetermined ones of the wavelength demultiplexers.

Description

[Technical Field]

[0001] The present invention relates to an optical transmission device and an optical transmission method. [Background technology]

[0002] Conventional communication networks generally consist of access, metro, and core networks, with an architecture that connects these in a hierarchical manner. When traffic is passed from the access to the metro, the optical signal is converted to an electrical signal at the boundary. Then, in order to provide services to a larger number of users over a wider bandwidth optical path, concentration and multiplexing are performed. The same is true when passing traffic from the metro to the core network. This allows for the sharing of facilities between users and between services, resulting in greater economy.

[0003] On the other hand, the line bandwidth per user and per service is limited. As a result, when transmitting large amounts of data such as high-definition video, data compression processing is required, resulting in significant delays. In addition, delays and jitter occur at electrical concentrating points and multiplexing points due to packet and frame queuing processes.

[0004] In response to this, a network configuration has been proposed that eliminates the electrical termination of optical signals required between layers in conventional networks. In this network configuration, access nodes are placed at the boundary between access and metro areas. These access nodes have the function of distributing optical signals according to the route of the optical path that terminates at the device that is the destination of the optical signal. This configuration enables optical through, return, and drop / insert, providing high-capacity, low-latency end-to-end optical paths between any points. Optical through is the function of forwarding optical signals across the boundary between access and metro areas. Return is the function of directly optically connecting user equipment accommodated in the same access node. Drop / insert is the function that realizes regeneration, wavelength conversion, and electrical processing in the network layer and service layer when necessary. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] “Open All-Photonic Network Functional Architecture,” Version 1.0, Innovative Optical Wireless Network (IOWN) Global Forum, January 2022, [Online] https: / / iowngf.org / technology / [Non-patent document 2] S. Gringeri, B. Basch, V. Shukla, R. Egorov, and T. Xia, “Flexible architectures for optical transport nodes and networks,” IEEE Communications Magazine, vol. 48, no. 7, pp. 40-50, 2010. [Non-patent document 3] Takuya Kanai, Kazuaki Honda, Yasunari Tanaka, Makoto Kaneko, Kazutaka Hara, Junichi Kani, Tomoaki Yoshida, “Photonic Gateway Supporting All-Photonics Networks”, Institute of Electronics, Information and Communication Engineers General Conference, B-8-20, March 2021 Summary of the Invention [Problem to be solved by the invention]

[0006] One of the optical nodes widely used in metropolitan networks and the like in conventional optical communication systems is an optical transmission device 90 such as a ROADM (Reconfigurable Optical Add / Drop Multiplexer). The optical transmission device 90 connects multiple locations and efficiently transfers traffic. FIG. 7 is a diagram showing an example of the configuration of a conventional optical transmission system. The optical transmission device 90 included in the optical transmission system shown in FIG. 7 includes a plurality of multiplexing / demultiplexing units 91, a plurality of wavelength multiplexing / demultiplexing units 92, and a control unit 99.

[0007] The multiplexer / demultiplexer 91 is connected to multiple transponders 30 and multiple wavelength multiplexer / demultiplexers 92. The multiplexer / demultiplexer 91 outputs an optical signal input from a transponder 30 to the wavelength multiplexer / demultiplexer 92, which is connected to a route accommodating an optical path ending at that transponder 30. The multiplexer / demultiplexer 91 also wavelength-multiplexes optical signals sharing the same route. The multiplexer / demultiplexer 91 also outputs an optical signal input from the wavelength multiplexer / demultiplexer 92 from a port connected to the transponder 30 that is the destination of that optical signal. The multiplexer / demultiplexer 91 is implemented using an M×N multicast switch, an M×N WSS (Wavelength Selective Switch), a configuration combining a 1×M WSS and a 1×N WSS, or the like. The M×N multicast switch is composed of, for example, M 1×N optical splitters / couplers and N M×1 optical switches.

[0008] The wavelength multiplexing / demultiplexing unit 92 is connected to a plurality of multiplexing / demultiplexing units 91 and a plurality of other wavelength multiplexing / demultiplexing units 92. The wavelength multiplexing / demultiplexing unit 92 wavelength-multiplexes the wavelength-multiplexed optical signals input from each multiplexing / demultiplexing unit 91 and each other wavelength multiplexing / demultiplexing unit 92. The wavelength multiplexing / demultiplexing unit 92 outputs the wavelength-multiplexed optical signal from a network-side port. Furthermore, the wavelength multiplexing / demultiplexing unit 92 outputs the optical signal input from the network-side port to the multiplexing / demultiplexing unit 91 or another wavelength multiplexing / demultiplexing unit 92 according to the route of the optical path ending at the transponder 30 that is the destination of this optical signal. The wavelength multiplexing / demultiplexing unit 92 may be implemented using, for example, a WXC (Wavelength Cross Connect) configured by WSS.

[0009] The control unit 99 controls the operations of the multiplexer / demultiplexer 91 and the wavelength multiplexer / demultiplexer 92. The control unit 99 may also assign wavelengths to the transponders 30. In an optical transmission device 90 such as a ROADM, an optical signal input from the transponder 30 is output from a network-side port of one of the wavelength multiplexer / demultiplexers 92 without undergoing optical / electrical conversion. Also, an optical signal input from a network-side port of the wavelength multiplexer / demultiplexer 92 is output to one of the transponders 30 without undergoing optical / electrical conversion. Therefore, when such an optical transmission device 90 is used as an access node, drop / insert cannot be realized. As a result, it becomes impossible to realize processes such as regeneration relay, wavelength conversion, and electrical processing in the network layer / service layer.

[0010] In view of the above circumstances, an object of the present invention is to provide a technique that enables electrical processing to be performed on a signal in an optical transmission system that transmits the signal without optical / electrical conversion. [Means for solving the problem]

[0011] One aspect of the present invention is an optical transmission device that transmits optical signals between a communication terminal device and a network without converting them into electrical signals, and includes a plurality of multiplexing / demultiplexing units that input and output optical signals to and from the communication terminal device connected to the device itself, a plurality of wavelength multiplexing / demultiplexing units that input and output optical signals to and from the network connected to the device itself, an upstream signal demultiplexing unit that outputs the upstream optical signal output from the multiplexing / demultiplexing units to an electrical processing unit that performs predetermined electrical processing on the optical signal, and an upstream signal multiplexing unit that outputs the upstream optical signal that has been electrically processed by the electrical processing unit to a predetermined wavelength multiplexing / demultiplexing unit.

[0012] Another aspect of the present invention is an optical transmission device that transmits optical signals between a communication terminal device and a network without converting them into electrical signals, and includes a plurality of multiplexing / demultiplexing units that input and output optical signals between the communication terminal device connected to the device itself, a plurality of wavelength multiplexing / demultiplexing units that input and output optical signals between the network connected to the device itself, a downstream signal demultiplexing unit that outputs downstream optical signals output from the wavelength multiplexing / demultiplexing units to an electrical processing unit that performs predetermined electrical processing on the optical signals, and a downstream signal multiplexing unit that outputs the downstream optical signals that have been subjected to the electrical processing by the electrical processing units to a predetermined multiplexing / demultiplexing unit.

[0013] Another aspect of the present invention is an optical transmission method for transmitting optical signals between a communication terminal device and a network without converting them into electrical signals, the optical transmission method comprising: a plurality of multiplexing / demultiplexing steps in which a multiplexing / demultiplexing unit inputs and outputs optical signals to and from the communication terminal device connected to the device; a plurality of wavelength multiplexing / demultiplexing steps in which a wavelength multiplexing / demultiplexing unit inputs and outputs optical signals to and from the network connected to the device; an upstream signal demultiplexing step in which an upstream signal demultiplexing unit outputs the upstream optical signal output from the multiplexing / demultiplexing unit to an electrical processing unit that performs predetermined electrical processing on the optical signal; and an upstream signal multiplexing step in which the upstream signal multiplexing unit outputs the upstream optical signal that has been subjected to the electrical processing by the electrical processing unit to a predetermined wavelength multiplexing / demultiplexing unit.

[0014] Another aspect of the present invention is an optical transmission method for transmitting optical signals between a communication terminal device and a network without converting them into electrical signals, the optical transmission method comprising: a plurality of multiplexing / demultiplexing steps in which a multiplexing / demultiplexing unit inputs and outputs optical signals to and from the communication terminal device connected to the device; a plurality of wavelength multiplexing / demultiplexing steps in which a wavelength multiplexing / demultiplexing unit inputs and outputs optical signals to and from the network connected to the device; a downstream signal demultiplexing step in which a downstream signal demultiplexing unit outputs the downstream optical signal output from the wavelength multiplexing / demultiplexing unit to an electrical processing unit that performs predetermined electrical processing on the optical signal; and a downstream signal multiplexing step in which a downstream signal multiplexing unit outputs the downstream optical signal that has been subjected to the electrical processing by the electrical processing unit to a predetermined multiplexing / demultiplexing unit. [Effects of the Invention]

[0015] According to the present invention, it becomes possible to perform electrical processing on signals in an optical transmission system that transmits signals without optical / electrical conversion. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a conventional optical transmission system m. [Figure 2] FIG. 1 is a diagram illustrating an example of the configuration of a conventional optical transmission system n. [Figure 3] 1 is a diagram illustrating a configuration of an optical transmission system 100a according to a first embodiment of the present invention. [Figure 4] 4 is a flowchart showing the operation of the optical transmission system 100a in the first embodiment of the present invention. [Figure 5] FIG. 10 is a diagram illustrating a configuration of an optical transmission system 100b according to a second embodiment of the present invention. [Figure 6] 10 is a flowchart showing the operation of the optical transmission system 100b according to the second embodiment of the present invention. [Figure 7] FIG. 1 illustrates a conventional optical transmission system. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an optical transmission device and an optical transmission method according to an embodiment of the present invention will be described with reference to the drawings.

[0018] To make it easier to understand the features of the optical transmission device and optical transmission method according to the embodiments of the present invention, we will first explain, for comparison, the prior art based on the technology described in Non-Patent Document 3. Non-Patent Document 3 describes the configuration of an optical transmission device that achieves drop and add functions by expanding the multiplexing / demultiplexing section.

[0019] 1 is a diagram showing an example of the configuration of a conventional optical transmission system 100m. The optical transmission system 100m includes an optical transmission device 10m and an electrical processing unit 20. The optical transmission device 10m and the electrical processing unit 20 are connected to each other so that optical signals can be input and output to and from each other. The optical transmission device 10m is connected to a network and a plurality of transponders 30. The optical transmission device 10m is connected to other optical transmission devices (not shown) via a network made up of optical fibers.

[0020] In FIG. 1, a network is located above the optical transmission device 10m. The term "network side" refers to a position relatively close to the network. The term "transponder side" refers to a position relatively close to the transponder 30.

[0021] The conventional optical transmission system 100m shown in FIG. 1 is configured to realize electrical processing of an upstream optical signal traveling from the lower side (transponder side) to the upper side (network side) in the figure.

[0022] The optical transmission device 10m includes a plurality (K units) of multiplexing / demultiplexing units 11, a plurality (H units) of wavelength multiplexing / demultiplexing units 12, and a control unit 19. Note that K and H are each an integer greater than or equal to 2. K and H may be the same value or different values.

[0023] The multiplexing / demultiplexing unit 11 is connected to a plurality (L units) of transponders 30, a plurality (H units) of wavelength multiplexing / demultiplexing units 12, and an electrical processing unit 20 so as to be able to input and output optical signals to and from each other.

[0024] For upstream traffic going from the bottom to the top in the figure, the multiplexer / demultiplexer unit 11 outputs the optical signal input from the transponder 30 to the wavelength multiplexer / demultiplexer unit 12 or the electrical processing unit 20. In this case, the wavelength multiplexer / demultiplexer unit 12 to which the output is directed is the wavelength multiplexer / demultiplexer unit 12 that connects to a route that accommodates an optical path whose endpoint is the transponder 30, the source of the optical signal. The multiplexer / demultiplexer unit 11 wavelength-multiplexes and outputs optical signals that share the route. If the output optical signal requires electrical processing by the electrical processing unit 20, the multiplexer / demultiplexer unit 11 outputs the optical signal from a network-side port to the electrical processing unit 20. With this configuration, an extraction function is realized.

[0025] For downstream traffic traveling from the top to the bottom in the figure, the multiplexer / demultiplexer 11 outputs the optical signal input from the wavelength multiplexer / demultiplexer 12 toward the transponder 30. At this time, the multiplexer / demultiplexer 11 outputs the optical signal from the port connected to the transponder 30 that is the destination of the output optical signal.

[0026] The multiplexing / demultiplexing unit 11 may be configured using, for example, an M×N multicast switch having M 1×N optical splitters / couplers and N M×1 optical switches. The multiplexing / demultiplexing unit 11 may be configured using, for example, an M×N WSS (Wavelength Selective Switch). The multiplexing / demultiplexing unit 11 may be configured using a device that combines a 1×M WSS and a 1×N WSS.

[0027] The wavelength multiplexing / demultiplexing unit 12 is connected to multiple (K units) multiplexing / demultiplexing units 11 and multiple ((H-1) units) other wavelength multiplexing / demultiplexing units 12 so as to mutually input and output optical signals. The wavelength multiplexing / demultiplexing unit 12 wavelength-multiplexes the wavelength-multiplexed optical signals input from the multiplexing / demultiplexing unit 11 and the other wavelength multiplexing / demultiplexing units 12, and outputs the multiplexed signals to the network from a network-side port.

[0028] The wavelength multiplexing / demultiplexing unit 12 outputs an optical signal input from a network-side port to the multiplexing / demultiplexing unit 11 or another wavelength multiplexing / demultiplexing unit 12. At this time, the wavelength multiplexing / demultiplexing unit 12 selects the multiplexing / demultiplexing unit 11 or wavelength multiplexing / demultiplexing unit 12 as the output destination according to the route of the optical path whose end point is the transponder 30 that is the destination of the output optical signal. The wavelength multiplexing / demultiplexing unit 12 may be configured using, for example, a WSS.

[0029] The control unit 19 is configured using a processor such as a CPU (Central Processing Unit) and a memory. The control unit 19 may operate by the processor executing a program. The control unit 19 controls the operation of the multiplexer / demultiplexer 11 and the wavelength multiplexer / demultiplexer 12. For example, the control unit 19 may control the connection relationship between ports in the multiplexer / demultiplexer 11. The control unit 19 may also assign wavelengths to the transponder 30.

[0030] The electrical processing unit 20 is connected to a plurality (K units) of multiplexing / demultiplexing units 11. The electrical processing unit 20 performs electrical processing on the optical signals output from the multiplexing / demultiplexing units 11 for upstream traffic. Specific examples of electrical processing performed by the electrical processing unit 20 include regenerative relay, wavelength conversion, electrical processing in the network layer, and electrical processing in the service layer. The electrical processing unit 20 outputs the electrically processed optical signals to the multiplexing / demultiplexing units 11 that are the input sources.

[0031] In this way, the upstream optical signal input from the network side port of the multiplexing / demultiplexing unit 11 to the electrical processing unit 20 is electrically processed by the electrical processing unit 20, and then input to the transponder side port of the multiplexing / demultiplexing unit 11 that input the optical signal to the electrical processing unit 20. With this configuration, the insertion function is realized.

[0032] In addition, the upstream optical signal input from the network side port of the multiplexer / demultiplexer unit 11 to the electrical processing unit 20 may be electrically processed by the electrical processing unit 20 and then input to a transponder side port of a multiplexer / demultiplexer unit 11 different from the multiplexer / demultiplexer unit 11 that output the optical signal to the electrical processing unit 20.

[0033] The multiplexer / demultiplexer 11 outputs the optical signal input from the electrical processing unit 20 to the wavelength multiplexer / demultiplexer 12. At this time, the wavelength multiplexer / demultiplexer 12 to which the signal is output is the wavelength multiplexer / demultiplexer 12 that connects to a route that accommodates an optical path whose endpoint is the transponder 30 that is the source of the optical signal.

[0034] 1, the multiple optical signals input to electrical processing unit 20 are output from different ports, but the multiple input optical signals may be output from the same port after undergoing electrical processing. For example, if electrical processing unit 20 is equipped with a muxponder function that multiplexes multiple signals and outputs them as a higher-speed optical signal, the multiple input optical signals will be output from the same port.

[0035] 1, the optical transmission system 100m is configured such that the upstream optical signal and the downstream optical signal travel through different optical fiber cores. However, there may be a section in which the optical signals travel through the same optical fiber core.

[0036] In addition, when the electrical processing unit 20 converts the wavelength of the optical signal input thereto to a wavelength different from the wavelength of the optical signal output from the transponder 30 and outputs the converted wavelength, wavelength collision does not occur even if the electrical processing unit 20 outputs the optical signal to the same multiplexing / demultiplexing unit 11 as the multiplexing / demultiplexing unit 11 to which the optical signal from the transponder 30 was input. Therefore, even in a contention-type configuration in which the multiplexing / demultiplexing unit 11 does not allow optical signals of the same wavelength to be input to different ports, the electrical processing unit 20 can output the optical signal to the same multiplexing / demultiplexing unit 11 as the multiplexing / demultiplexing unit 11 to which the optical signal from the transponder 30 was input. In this case, the wavelength of the optical signal output from the electrical processing unit 20 is different from the wavelength of the optical signal input to the multiplexing / demultiplexing unit 11 from the transponder 30 and the wavelength of other optical signals input to the multiplexing / demultiplexing unit 11 from the electrical processing unit 20.

[0037] 1, it is necessary to secure a port used for an add function (hereinafter referred to as an "add port") at the transponder-side port of the multiplexing / demultiplexing unit 11. Here, if the optical signals output from the electrical processing unit 20 are input to the multiplexing / demultiplexing unit 11 without being wavelength-multiplexed, the same number of add ports as the number of optical paths distributed to the electrical processing unit 20 are required. Also, if the optical signals output from the electrical processing unit 20 are wavelength-multiplexed and input to the multiplexing / demultiplexing unit 11 for each path accommodating the optical paths through which the optical signals output from the electrical processing unit 20 are transmitted, the same number of add ports as the number of paths are required.

[0038] Therefore, when the number of transponder-side ports of the multiplexing / demultiplexing unit 11 is the same as the number of transponder-side ports of the multiplexing / demultiplexing unit 91 of a conventional optical transmission device 90 that does not have a drop or add function as shown in Fig. 7, for example, the number of transponders 30 that can be accommodated per multiplexing / demultiplexing unit 11 decreases. Alternatively, in order to make the number of transponders 30 that can be accommodated per multiplexing / demultiplexing unit 11 the same as the number of transponders 30 that can be accommodated per multiplexing / demultiplexing unit 91 of a conventional optical transmission device 90 that does not have a drop or add function as shown in Fig. 7, it is necessary to increase the scale of the configuration of the multiplexing / demultiplexing unit 11 and increase the number of transponder-side ports.

[0039] The conventional optical transmission system 100n shown in FIG. 2 is configured to perform electrical processing on downstream optical signals traveling from the upper side (network side) to the lower side (transponder side) in the figure.

[0040] The optical transmission device 10n includes a plurality (K units) of multiplexing / demultiplexing units 11, a plurality (H units) of wavelength multiplexing / demultiplexing units 12, and a control unit 19. Note that K and H are each an integer greater than or equal to 2. K and H may be the same value or different values.

[0041] The multiplexer / demultiplexer 11 is connected to a plurality (L units) of transponders 30, a plurality (H units) of wavelength multiplexer / demultiplexers 12, and an electrical processing unit 20 so as to be able to input and output optical signals to and from each other.

[0042] For upstream traffic going from the bottom to the top in the figure, the multiplexer / demultiplexer 11 outputs the optical signal input from the transponder 30 to the wavelength multiplexer / demultiplexer 12. In this case, the wavelength multiplexer / demultiplexer 12 to which the signal is output is the wavelength multiplexer / demultiplexer 12 that connects to a route that accommodates an optical path whose end point is the transponder 30 that is the source of the optical signal. The multiplexer / demultiplexer 11 wavelength-multiplexes the optical signals that share the route and outputs them.

[0043] For downstream traffic traveling from the top to the bottom in the figure, the multiplexing / demultiplexing unit 11 outputs the optical signal input from the wavelength multiplexing / demultiplexing unit 12 toward the transponder 30 or the electrical processing unit 20. At this time, the multiplexing / demultiplexing unit 11 outputs the optical signal from the port connected to the transponder 30 that is the destination of the output optical signal. If the output optical signal requires electrical processing by the electrical processing unit 20, the multiplexing / demultiplexing unit 11 outputs the optical signal from the transponder-side port to the electrical processing unit 20. With this configuration, the extraction function is realized.

[0044] The multiplexing / demultiplexing unit 11 may be configured using, for example, an M×N multicast switch having M 1×N optical splitters / couplers and N M×1 optical switches. The multiplexing / demultiplexing unit 11 may be configured using, for example, an M×N WSS. The multiplexing / demultiplexing unit 11 may be configured using a device that combines a 1×M WSS and a 1×N WSS.

[0045] The wavelength multiplexing / demultiplexing unit 12 is connected to multiple (K units) multiplexing / demultiplexing units 11 and multiple ((H-1) units) other wavelength multiplexing / demultiplexing units 12 so as to mutually input and output optical signals. The wavelength multiplexing / demultiplexing unit 12 wavelength-multiplexes the wavelength-multiplexed optical signals input from the multiplexing / demultiplexing unit 11 and the other wavelength multiplexing / demultiplexing units 12, and outputs the multiplexed signals to the network from a network-side port.

[0046] The wavelength multiplexing / demultiplexing unit 12 outputs an optical signal input from a network-side port to the multiplexing / demultiplexing unit 11 or another wavelength multiplexing / demultiplexing unit 12. At this time, the wavelength multiplexing / demultiplexing unit 12 selects the multiplexing / demultiplexing unit 11 or wavelength multiplexing / demultiplexing unit 12 as the output destination according to the route of the optical path whose end point is the transponder 30 that is the destination of the output optical signal. The wavelength multiplexing / demultiplexing unit 12 may be configured using, for example, a WSS.

[0047] The control unit 19 is configured using a processor such as a CPU and a memory. The control unit 19 may operate by the processor executing a program. The control unit 19 controls the operation of the multiplexing / demultiplexing unit 11 and the wavelength multiplexing / demultiplexing unit 12. For example, the control unit 19 may control the connection relationship between ports in the multiplexing / demultiplexing unit 11. The control unit 19 may also assign wavelengths to the transponder 30.

[0048] The electrical processing unit 20 is connected to a plurality (K units) of multiplexing / demultiplexing units 11. The electrical processing unit 20 performs electrical processing on the optical signals output from the multiplexing / demultiplexing units 11 for downstream traffic. Specific examples of electrical processing performed by the electrical processing unit 20 include regeneration relay, wavelength conversion, electrical processing in the network layer, and electrical processing in the service layer. The electrical processing unit 20 outputs the optical signals that have undergone electrical processing toward the multiplexing / demultiplexing units 11 that are the input sources.

[0049] In this way, the downstream optical signal input from the transponder side port of the multiplexing / demultiplexing unit 11 to the electrical processing unit 20 is electrically processed by the electrical processing unit 20, and then input to the network side port of the multiplexing / demultiplexing unit 11 that input the optical signal to the electrical processing unit 20. With this configuration, an insertion function is realized.

[0050] In addition, the downstream optical signal input from the transponder side port of the multiplexer / demultiplexer unit 11 to the electrical processing unit 20 may be electrically processed by the electrical processing unit 20 and then input to a network side port of the multiplexer / demultiplexer unit 11 different from the multiplexer / demultiplexer unit 11 that input the optical signal to the electrical processing unit 20.

[0051] The multiplexing / demultiplexing unit 11 outputs the optical signal input from the electrical processing unit 20 toward the transponder 30. At this time, the multiplexing / demultiplexing unit 11 outputs the optical signal from the port connected to the transponder 30 that is the destination of the output optical signal.

[0052] 2, optical signals input to the electrical processing unit 20 from different ports are output from different ports after undergoing electrical processing. However, optical signals input to the electrical processing unit 20 from one port may be output from multiple ports after undergoing electrical processing. For example, a configuration may be adopted in which a high-speed signal is separated and output as slower optical signals, or a configuration in which the same signal is copied and output from multiple ports.

[0053] 2, the optical transmission system 100n is configured such that the upstream optical signal and the downstream optical signal travel through different optical fiber cores. However, there may be a section in which the optical signals travel through the same optical fiber core.

[0054] In addition, when the electrical processing unit 20 converts the wavelength of the optical signal input thereto to a wavelength different from the wavelength of the optical signal output from the wavelength multiplexing / demultiplexing unit 12 and outputs the converted wavelength, wavelength collision does not occur even if the electrical processing unit 20 outputs the optical signal to the same multiplexing / demultiplexing unit 11 as the multiplexing / demultiplexing unit 11 to which the optical signal was input from the wavelength multiplexing / demultiplexing unit 12. Therefore, even in a contention-type configuration in which the multiplexing / demultiplexing unit 11 does not allow optical signals of the same wavelength to be input to different ports, the electrical processing unit 20 can output the optical signal to the same multiplexing / demultiplexing unit 11 as the multiplexing / demultiplexing unit 11 to which the optical signal was input from the wavelength multiplexing / demultiplexing unit 12. In this case, the wavelength of the optical signal output from the electrical processing unit 20 is different from the wavelength of the optical signal input from the wavelength multiplexing / demultiplexing unit 12 to the multiplexing / demultiplexing unit 11 and the wavelength of other optical signals input from the electrical processing unit 20 to the multiplexing / demultiplexing unit 11.

[0055] In the configuration of the conventional optical transmission system 100n shown in Figure 2, it is necessary to secure ports used for the extraction function (hereinafter referred to as "extraction ports") in the transponder side port of the multiplexing / demultiplexing unit 11, the number of which is equal to the number of optical paths distributed to the electrical processing unit 20.

[0056] Therefore, when the number of transponder-side ports of the multiplexing / demultiplexing unit 11 is the same as the number of transponder-side ports of the multiplexing / demultiplexing unit 91 of a conventional optical transmission device 90 that does not have a dropper or add function as shown in Fig. 7, for example, the number of transponders 30 that can be accommodated per multiplexing / demultiplexing unit 11 decreases. Alternatively, in order to make the number of transponders 30 that can be accommodated per multiplexing / demultiplexing unit 11 the same as the number of transponders 30 that can be accommodated per multiplexing / demultiplexing unit 91 of a conventional optical transmission device 90 that does not have a dropper or add function as shown in Fig. 7, it is necessary to increase the scale of the configuration of the multiplexing / demultiplexing unit 11 and increase the number of transponder-side ports.

[0057] 1 and the configuration of the conventional optical transmission system 100n shown in Fig. 2, when performing electrical processing on optical signals, there is a problem that the number of transponders 30 that can be accommodated per multiplexing / demultiplexing unit 11 decreases or that it is necessary to increase the scale of the configuration of the multiplexing / demultiplexing unit 11. In contrast, the optical transmission system in the embodiment of the present invention described below can perform electrical processing on optical signals without reducing the number of transponders 30 that can be accommodated per multiplexing / demultiplexing unit 11 or increasing the scale of the configuration of the multiplexing / demultiplexing unit 11.

[0058] First Embodiment An optical transmission system 100a according to a first embodiment of the present invention will be described below with reference to the drawings.

[0059] [Configuration of optical transmission system] Fig. 3 is a diagram showing the configuration of an optical transmission system 100a according to the first embodiment of the present invention. As shown in Fig. 3, the optical transmission system 100a includes an optical transmission device 10a and an electrical processing unit 20. The optical transmission device 10a and the electrical processing unit 20 are connected to each other so that optical signals can be input and output to and from each other.

[0060] The optical transmission device 10a is connected to a network and a transponder 30. The optical transmission device 10a is connected to other optical transmission devices (not shown) via a network configured with optical fibers.

[0061] 3, the network is located above the optical transmission device 10a. The term "network side" refers to a position relatively close to the network. The transponder 30 is located below the optical transmission device 10a. The term "transponder side" refers to a position relatively close to the transponder 30.

[0062] The optical transmission system 100a according to the first embodiment shown in FIG. 3 is configured to realize electrical processing of an upstream optical signal traveling from the lower side (transponder side) to the upper side (network side) in the figure.

[0063] 3, the optical transmission device 10a includes a plurality (K units) of first multiplexing / demultiplexing units 11, a plurality (H units) of wavelength multiplexing / demultiplexing units 12, a second multiplexing / demultiplexing unit 13, and a control unit 19. Note that K and H are each an integer greater than or equal to 2. K and H may be the same value or different values.

[0064] 3, the first multiplexing / demultiplexing unit 11 is made up of a drop function unit (for downstream) and an add function unit (for upstream). Also, as shown in FIG. 3, the second multiplexing / demultiplexing unit 13 is made up of a drop function unit (for upstream) 13p and an add function unit (for upstream) 13q, which are arranged to sandwich the electrical processing unit 20.

[0065] The first multiplexing / demultiplexing unit 11 is connected to a plurality (L units) of transponders 30 and a plurality (H units) of wavelength multiplexing / demultiplexing units 12 so as to be able to input and output optical signals to and from them. The first multiplexing / demultiplexing unit 11 is also connected to a extraction function unit (upstream) 13p constituting the second multiplexing / demultiplexing unit 13 so as to be able to output optical signals to that extraction function unit (upstream) 13p.

[0066] For upstream traffic traveling from the bottom to the top in the figure, the adding function unit (for upstream) of the first multiplexing / demultiplexing unit 11 outputs the optical signal input from the transponder 30 toward the wavelength multiplexing / demultiplexing unit 12 or the dropping function unit (for upstream) 13p constituting the second multiplexing / demultiplexing unit 13. In this case, the wavelength multiplexing / demultiplexing unit 12 serving as the output destination is the wavelength multiplexing / demultiplexing unit 12 that connects to a route accommodating an optical path whose endpoint is the transponder 30 that is the transmission source of the optical signal. The adding function unit (for upstream) of the first multiplexing / demultiplexing unit 11 wavelength-multiplexes optical signals sharing the route and outputs the multiplexed optical signals.

[0067] When the output optical signal requires electrical processing by the electrical processing unit 20, the add function unit (for upstream) of the first multiplexing / demultiplexing unit 11 outputs the optical signal from the network side port to the drop function unit (for upstream) 13p that constitutes the second multiplexing / demultiplexing unit 13. With this configuration, the drop function is realized.

[0068] For downstream traffic going from the top to the bottom in the figure, the extraction function unit (for downstream) of the first multiplexing / demultiplexing unit 11 outputs the optical signal input from the wavelength multiplexing / demultiplexing unit 12 toward the transponder 30. At this time, the multiplexing / demultiplexing unit 11 outputs the optical signal from the port connected to the transponder 30 that is the destination of the output optical signal.

[0069] The add function unit (upstream) and drop function unit (downstream) of the first multiplexing / demultiplexing unit 11 may be configured using, for example, an M×N multicast switch having M 1×N optical splitters / couplers and N M×1 optical switches. The add function unit (upstream) and drop function unit (downstream) of the first multiplexing / demultiplexing unit 11 may be configured using, for example, an M×N WSS. The add function unit (upstream) and drop function unit (downstream) of the first multiplexing / demultiplexing unit 11 may be configured using a device that combines a 1×M WSS and a 1×N WSS.

[0070] The add function unit (for upstream) and drop function unit (for downstream) of the first multiplexing / demultiplexing unit 11 may be configured by combining, for example, a fiber cross connect (FXC) device with wavelength multiplexing / demultiplexing means such as an arrayed waveguide grating (AWG) or WSS. The FXC is configured using a micro electro mechanical system (MEMS) or a piezoelectric actuator as described in Non-Patent Document 3. The FXC outputs light input from each port to a port that is set as the connection port for that port, regardless of wavelength.

[0071] The wavelength multiplexing / demultiplexing unit 12 is connected to a plurality (K units) of first multiplexing / demultiplexing units 11 and a plurality (H-1 units) of other wavelength multiplexing / demultiplexing units 12 so as to mutually input and output optical signals. In addition, the wavelength multiplexing / demultiplexing unit 12 is connected to an add function unit (upstream) 13q constituting the second multiplexing / demultiplexing unit 13 so as to input optical signals output from the add function unit (upstream) 13q. The wavelength multiplexing / demultiplexing unit 12 wavelength-multiplexes the wavelength-multiplexed optical signals input from the add function unit (upstream) of the first multiplexing / demultiplexing unit 11, the other wavelength multiplexing / demultiplexing units 12, and the second multiplexing / demultiplexing unit 13, and outputs the multiplexed optical signals to the network from a network-side port.

[0072] The wavelength multiplexing / demultiplexing unit 12 outputs an optical signal input from a network-side port to the first multiplexing / demultiplexing unit 11 or another wavelength multiplexing / demultiplexing unit 12. At this time, the wavelength multiplexing / demultiplexing unit 12 selects the first multiplexing / demultiplexing unit 11 or another wavelength multiplexing / demultiplexing unit 12 as the output destination, depending on the route of the optical path whose end point is the transponder 30 that is the destination of the output optical signal. The wavelength multiplexing / demultiplexing unit 12 may be implemented using, for example, a wavelength cross connect (WXC) configured by a WSS.

[0073] The drop function unit (for upstream) 13p constituting the second multiplexing / demultiplexing unit 13 is connected to the add function units (for upstream) of the plurality (K units) of first multiplexing / demultiplexing units 11 and the electrical processing unit 20. For upstream traffic, the drop function unit (for upstream) 13p separates the optical signals that are wavelength-multiplexed and output from the network-side ports of the add function units (for upstream) of the first multiplexing / demultiplexing unit 11 into separate signals by wavelength and outputs them to the electrical processing unit 20.

[0074] The adding function unit (for upstream) 13q constituting the second multiplexing / demultiplexing unit 13 is connected to the electrical processing unit 20 and a plurality (H units) of wavelength multiplexing / demultiplexing units 12. For upstream traffic, the adding function unit (for upstream) 13q outputs the optical signal output from the electrical processing unit 20 to the transponder side port of the wavelength multiplexing / demultiplexing unit 12. With such a configuration, the adding function is realized.

[0075] The add function unit (for upstream) 13q outputs the optical signal to the wavelength multiplexing / demultiplexing unit 12 that connects to a route that accommodates an optical path that transmits the optical signal. The add function unit (for upstream) 13q wavelength-multiplexes optical signals that share the route.

[0076] The drop function unit (for upstream) 13p and the add function unit (for upstream) 13q constituting the second multiplexing / demultiplexing unit 13 may have the same configuration as the add function unit (for upstream) and the drop function unit (for downstream) of the first multiplexing / demultiplexing unit 11. The second multiplexing / demultiplexing unit 13 may be configured by combining, for example, a fiber cross connect (FXC) device with a wavelength multiplexing / demultiplexing means such as an arrayed waveguide grating (AWG) or a WSS. The FXC is configured using a microelectromechanical system (MEMS) or a piezoelectric actuator as described in Non-Patent Document 3. The FXC outputs light input from each port to a port that is set as the connection port for that port, regardless of wavelength.

[0077] The control unit 19 is configured using a processor such as a CPU and a memory. The control unit 19 may operate by the processor executing a program. The control unit 19 controls the operations of the first multiplexing / demultiplexing unit 11, the wavelength multiplexing / demultiplexing unit 12, and the second multiplexing / demultiplexing unit 13. For example, the control unit 19 may control the connection relationship between ports in the first multiplexing / demultiplexing unit 11 and the second multiplexing / demultiplexing unit 13. The control unit 19 may also assign wavelengths to the transponder 30.

[0078] The electrical processing unit 20 is connected to the drop function unit (upstream) 13p and the add function unit (upstream) 13q that constitute the second multiplexing / demultiplexing unit 13. For upstream traffic, the electrical processing unit 20 performs electrical processing on the optical signal input from the drop function unit (upstream) 13p that constitutes the second multiplexing / demultiplexing unit 13. Specific examples of electrical processing performed by the electrical processing unit 20 include regeneration relay, wavelength conversion, electrical processing in the network layer, and electrical processing in the service layer. The electrical processing unit 20 outputs the optical signal that has undergone electrical processing to the add function unit (upstream) 13q.

[0079] 3, the multiple optical signals input to electrical processing unit 20 are output from different ports, but the multiple input optical signals may be output from the same port after undergoing electrical processing. For example, if electrical processing unit 20 is equipped with a muxponder function that multiplexes multiple signals and outputs them as a higher-speed optical signal, the multiple input optical signals will be output from the same port.

[0080] 3, the optical transmission system 100a is configured such that the upstream optical signal and the downstream optical signal travel through different optical fiber cores. However, there may be a section in which the optical signals travel through the same optical fiber core.

[0081] [Operation of optical transmission system] An example of the operation of the optical transmission system 100a for upstream traffic will be described below. Fig. 4 is a flowchart showing the operation of the optical transmission system 100a according to the first embodiment of the present invention. The operation shown in the flowchart in Fig. 4 is started, for example, when an upstream optical signal transmitted from the transponder 30 is input to the optical transmission device 10a.

[0082] An upstream optical signal transmitted from the transponder 30 is input to the add function unit (for upstream) of the first multiplexing / demultiplexing unit 11 (step S101). If electrical processing by the electrical processing unit 20 is required for the input optical signal (step S102: YES), the add function unit (for upstream) of the first multiplexing / demultiplexing unit 11 wavelength-multiplexes the input upstream optical signal and outputs it from the network-side port to the drop function unit (for upstream) 13p that constitutes the second multiplexing / demultiplexing unit 13 (step S103).

[0083] The extraction function unit (for upstream) 13p separates the wavelength-multiplexed upstream optical signal input from the addition function unit (for upstream) of the first multiplexing / demultiplexing unit 11 into wavelengths and outputs them to the electrical processing unit 20 (step S104).

[0084] The electrical processing unit 20 performs electrical processing on the upstream optical signal input from the extraction function unit (for upstream) 13p (step S105). The electrical processing unit 20 outputs the electrically processed upstream optical signal to the addition function unit (for upstream) 13q that constitutes the second multiplexing / demultiplexing unit 13 (step S106).

[0085] The insertion function unit (for uplink) 13q wavelength-multiplexes the uplink optical signals for each wavelength input from the electrical processing unit 20 and outputs them to the transponder side port of the wavelength multiplexing / demultiplexing unit 12 that is connected to a route that accommodates an optical path that transmits the optical signals (step S107).

[0086] On the other hand, if electrical processing by the electrical processing unit 20 is not required for the upstream optical signal input to the insertion function unit (for upstream) of the first multiplexing / demultiplexing unit 11 (step S102: NO), the insertion function unit (for upstream) of the first multiplexing / demultiplexing unit 11 wavelength-multiplexes the input upstream optical signal and outputs it to the transponder side port of the wavelength multiplexing / demultiplexing unit 12 that is connected to a route that accommodates an optical path that transmits the optical signal (step S108).

[0087] The wavelength multiplexing / demultiplexing unit 12 wavelength-multiplexes the wavelength-multiplexed upstream optical signals input to the transponder-side port from the add function unit (for upstream) of the first multiplexing / demultiplexing unit 11, other wavelength multiplexing / demultiplexing units 12, and add function unit (for upstream) 13q constituting the second multiplexing / demultiplexing unit 13. The wavelength multiplexing / demultiplexing unit 12 outputs the wavelength-multiplexed upstream optical signals from the network-side port to the network (step S109).

[0088] This completes the operation of the optical transmission system 100a shown in FIG.

[0089] As described above, the optical transmission device 10a according to the first embodiment of the present invention includes the second multiplexing / demultiplexing unit 13 (the drop function unit (upstream) 13p and the add function unit (upstream) 13q) disposed on either side of the electrical processing unit 20. With this configuration, the optical transmission device 10a according to the first embodiment does not need to provide an add port at the transponder-side port of the first multiplexing / demultiplexing unit 11, as in the conventional optical transmission device 10m shown in FIG. 1 . This allows the optical transmission device 10a according to the first embodiment to perform electrical processing on optical signals of upstream traffic without reducing the number of transponders 30 that can be accommodated per first multiplexing / demultiplexing unit 11 or increasing the scale of the configuration of the first multiplexing / demultiplexing unit 11.

[0090] <Second embodiment> An optical transmission system 100b according to the second embodiment of the present invention will be described below with reference to the drawings.

[0091] [Configuration of optical transmission system] Fig. 5 is a diagram showing the configuration of an optical transmission system 100b according to a second embodiment of the present invention. As shown in Fig. 5, the optical transmission system 100b includes an optical transmission device 10b and an electrical processing unit 20. The optical transmission device 10b and the electrical processing unit 20 are connected to each other so that optical signals can be input and output to and from each other.

[0092] An optical transmission system 100b according to the second embodiment shown in FIG. 5 is configured to perform electrical processing on downstream optical signals traveling from the upper side (network side) to the lower side (transponder side) in the figure.

[0093] As shown in FIG. 5, the optical transmission device 10b includes a plurality (K units) of first multiplexing / demultiplexing units 11, a plurality (H units) of wavelength multiplexing / demultiplexing units 12, a second multiplexing / demultiplexing unit 13, and a control unit 19. Note that K and H are each an integer of 2 or greater. K and H may be the same value or different values. Also, as shown in FIG. 5, the first multiplexing / demultiplexing unit 11 includes a drop function unit (for downstream) and an add function unit (for upstream). Also, as shown in FIG. 5, the second multiplexing / demultiplexing unit 13 includes a drop function unit (for downstream) 13r and an add function unit (for downstream) 13s, which are arranged to sandwich an electrical processing unit 20.

[0094] The first multiplexing / demultiplexing unit 11 is connected to a plurality (L units) of transponders 30 and a plurality (H units) of wavelength multiplexing / demultiplexing units 12 so as to be able to input and output optical signals to and from them. The first multiplexing / demultiplexing unit 11 is also connected to an adding function unit (downstream) 13s constituting the second multiplexing / demultiplexing unit 13 so as to receive the optical signal output from that adding function unit.

[0095] For upstream traffic going from the bottom to the top in the figure, the adding function unit (for upstream) of the first multiplexing / demultiplexing unit 11 outputs the optical signal input from the transponder 30 to the wavelength multiplexing / demultiplexing unit 12. In this case, the wavelength multiplexing / demultiplexing unit 12 to which the signal is output is the wavelength multiplexing / demultiplexing unit 12 that connects to a route that accommodates an optical path whose endpoint is the transponder 30 that is the transmission source of the optical signal. The adding function unit (for upstream) of the first multiplexing / demultiplexing unit 11 wavelength-multiplexes the optical signals that share the route and outputs them.

[0096] For downstream traffic traveling from the top to the bottom in the figure, the extraction function unit (for downstream) of the first multiplexing / demultiplexing unit 11 outputs optical signals input from the wavelength multiplexing / demultiplexing unit 12 and the addition function unit (for downstream) 13s constituting the second multiplexing / demultiplexing unit 13 toward the transponder 30. At this time, the extraction function unit (for downstream) of the first multiplexing / demultiplexing unit 11 outputs the optical signal from the port connected to the transponder 30 that is the destination of the output optical signal.

[0097] The add function unit (for upstream) and drop function unit (for downstream) of the first multiplexing / demultiplexing unit 11 may be configured using, for example, an M×N multicast switch having M 1×N optical splitters / couplers and N M×1 optical switches. The multiplexing / demultiplexing unit 11 may be configured using, for example, an M×N WSS. The multiplexing / demultiplexing unit 11 may be configured using a device that combines a 1×M WSS and a 1×N WSS.

[0098] The add function unit (for upstream) and drop function unit (for downstream) of the first multiplexing / demultiplexing unit 11 may be configured by combining, for example, an FXC device with wavelength multiplexing / demultiplexing means such as an arrayed waveguide grating (AWG) or WSS. The FXC is configured using MEMS or a piezoelectric actuator as described in Non-Patent Document 3. The FXC outputs light input from each port to a port that is set as the connection port for that port, regardless of wavelength.

[0099] The wavelength multiplexing / demultiplexing unit 12 is connected to a plurality (K units) of first multiplexing / demultiplexing units 11 and a plurality (H-1) of other wavelength multiplexing / demultiplexing units 12 so as to input and output optical signals to and from each other. The wavelength multiplexing / demultiplexing unit 12 is also connected to a drop function unit (downstream) 13r constituting the second multiplexing / demultiplexing unit 13 so as to output an optical signal to the drop function unit (downstream) 13r. The wavelength multiplexing / demultiplexing unit 12 wavelength-multiplexes the wavelength-multiplexed optical signals input from the add function unit (upstream) of the first multiplexing / demultiplexing unit 11 and the other wavelength multiplexing / demultiplexing units 12, and outputs the multiplexed optical signals to the network from a network-side port.

[0100] The wavelength multiplexing / demultiplexing unit 12 outputs the optical signal input from the network side port to the adding function unit (for upstream) of the first multiplexing / demultiplexing unit 11, another wavelength multiplexing / demultiplexing unit 12, or a dropping function unit (for downstream) 13r constituting the second multiplexing / demultiplexing unit 13. At this time, the wavelength multiplexing / demultiplexing unit 12 selects the first multiplexing / demultiplexing unit 11 or another wavelength multiplexing / demultiplexing unit 12 as the output destination, depending on the route of the optical path whose end point is the transponder 30 that is the destination of the output optical signal.

[0101] When the output optical signal needs electrical processing by the electrical processing unit 20, the wavelength multiplexing / demultiplexing unit 12 outputs the optical signal from the transponder side port to the extraction function unit (downstream) 13r. With this configuration, the extraction function is realized.

[0102] The wavelength multiplexer / demultiplexer 12 may be implemented using, for example, a WXC (Wavelength Cross Connect) configured by a WSS.

[0103] The extraction function unit (for downstream) 13r constituting the second multiplexing / demultiplexing unit 13 is connected to the plurality of wavelength multiplexing / demultiplexing units 12 and the electrical processing unit 20. For downstream traffic, the extraction function unit (for downstream) 13r separates the optical signals wavelength-multiplexed and output from the wavelength multiplexing / demultiplexing unit 12 into individual wavelengths and outputs them to the electrical processing unit 20.

[0104] The add function unit (downstream) 13s constituting the second multiplexing / demultiplexing unit 13 is connected to the electrical processing unit 20 and the drop function units (downstream) of the plurality of first multiplexing / demultiplexing units 11. For downstream traffic, the add function unit (downstream) 13s outputs the optical signal output from the electrical processing unit 20 to the network side port of the drop function unit (downstream) of the first multiplexing / demultiplexing unit 11. With this configuration, the add function is realized.

[0105] The add function unit (downstream) 13s outputs the optical signal toward the drop function unit (downstream) of the first multiplexing / demultiplexing unit 11 that is connected to the transponder 30 that is the destination of the optical signal. The add function unit (downstream) 13s wavelength-multiplexes optical signals that share the path.

[0106] The drop function unit (downstream) 13r and the add function unit (downstream) 13s constituting the second multiplexing / demultiplexing unit 13 may have the same configuration as the add function unit (upstream) and drop function unit (downstream) of the first multiplexing / demultiplexing unit 11. The second multiplexing / demultiplexing unit 13 may be configured by combining, for example, a fiber cross connect (FXC) device with a wavelength multiplexing / demultiplexing means such as an arrayed waveguide grating (AWG) or WSS. The FXC is configured using a microelectromechanical system (MEMS) or a piezoelectric actuator as described in Non-Patent Document 3. The FXC outputs light input from each port to a port that is set as the connection port for that port, regardless of wavelength.

[0107] The control unit 19 is configured using a processor such as a CPU and a memory. The control unit 19 may operate by the processor executing a program. The control unit 19 controls the operations of the first multiplexing / demultiplexing unit 11, the wavelength multiplexing / demultiplexing unit 12, and the second multiplexing / demultiplexing unit 13. For example, the control unit 19 may control the connection relationship between ports in the first multiplexing / demultiplexing unit 11 and the second multiplexing / demultiplexing unit 13. The control unit 19 may also assign wavelengths to the transponder 30.

[0108] The electrical processing unit 20 is connected to the drop function unit (downstream) 13r and the add function unit (downstream) 13s that constitute the second multiplexing / demultiplexing unit 13. For downstream traffic, the electrical processing unit 20 performs electrical processing on the optical signal input from the drop function unit (downstream) 13r that constitutes the second multiplexing / demultiplexing unit 13. Specific examples of electrical processing performed by the electrical processing unit 20 include regeneration relay, wavelength conversion, electrical processing in the network layer, and electrical processing in the service layer. The electrical processing unit 20 outputs the electrically processed optical signal to the add function unit (downstream) 13s.

[0109] 5, optical signals input to electrical processing unit 20 from different ports are output from different ports after undergoing electrical processing. However, optical signals input to electrical processing unit 20 from one port may be output from multiple ports after undergoing electrical processing. For example, a configuration may be used in which a high-speed signal is separated and output as slower optical signals, or a configuration in which the same signal is copied and output from multiple ports.

[0110] 5, the optical transmission system 100b is configured such that the upstream optical signal and the downstream optical signal travel through different optical fiber cores. However, there may be a section in which the optical signals travel through the same optical fiber core.

[0111] [Operation of optical transmission system] An example of the operation of the optical transmission system 100b for downstream traffic will be described below. Fig. 6 is a flowchart showing the operation of the optical transmission system 100b according to the second embodiment of the present invention. The operation shown in the flowchart in Fig. 6 is started, for example, when a downstream optical signal transmitted from the network side is input to the optical transmission device 10b.

[0112] A downstream optical signal transmitted from the network side is input to the wavelength multiplexing / demultiplexing unit 12 (for downstream) (step S201). If the input downstream optical signal requires electrical processing by the electrical processing unit 20 (step S202: YES), the wavelength multiplexing / demultiplexing unit 12 (for downstream) wavelength-multiplexes the input downstream optical signal and outputs it from the transponder-side port to the extraction function unit (for downstream) 13r that constitutes the second multiplexing / demultiplexing unit 13 (step S203).

[0113] The extraction function unit (for downstream) 13r separates the wavelength-multiplexed downstream optical signal input from the wavelength multiplexing / demultiplexing unit 12 (for downstream) into wavelengths and outputs the separated signals to the electrical processing unit 20 (step S204).

[0114] The electrical processing unit 20 performs electrical processing on the downstream optical signal input from the drop function unit (downstream) 13r (step S205). The electrical processing unit 20 outputs the electrically processed downstream optical signal to the add function unit (downstream) 13s that constitutes the second multiplexing / demultiplexing unit 13 (step S206).

[0115] The insertion function unit (downstream) 13s wavelength-multiplexes the downstream optical signals for each wavelength input from the electrical processing unit 20 and outputs them to the network side port of the first multiplexing / demultiplexing unit 11 that connects to a route that accommodates an optical path that transmits the optical signals (step S207).

[0116] On the other hand, if electrical processing by the electrical processing unit 20 is not required for the downstream optical signal input to the wavelength multiplexing / demultiplexing unit 12 (downstream) (step S202: NO), the wavelength multiplexing / demultiplexing unit 12 (downstream) wavelength-multiplexes the input downstream optical signal according to the route of the optical path whose endpoint is the transponder 30 that is the destination of the optical signal, and outputs it to the network side port of the first multiplexing / demultiplexing unit 11 that connects to the route that accommodates the optical path that transmits the optical signal, or to another wavelength multiplexing / demultiplexing unit 12 (downstream) (step S208).

[0117] The first multiplexing / demultiplexing unit 11 wavelength-multiplexes the wavelength-multiplexed downstream optical signals input to the network-side port from the wavelength multiplexing / demultiplexing unit 12 (downstream) and the add function unit (downstream) 13s constituting the second multiplexing / demultiplexing unit 13. The first multiplexing / demultiplexing unit 11 outputs the wavelength-multiplexed downstream optical signal from the transponder-side port to the transponder 30 (step S209).

[0118] This completes the operation of the optical transmission system 100b shown in FIG.

[0119] As described above, the optical transmission device 10b according to the second embodiment of the present invention includes the second multiplexing / demultiplexing unit 13 (the drop function unit (downstream) 13r and the add function unit (downstream) 13s) disposed on either side of the electrical processing unit 20. With this configuration, the optical transmission device 10b according to the second embodiment does not need to provide a drop port at the transponder-side port of the first multiplexing / demultiplexing unit 11, as in the conventional optical transmission device 10n shown in FIG. 2, for example. This allows the optical transmission device 10b according to the second embodiment to perform electrical processing on downstream traffic optical signals without reducing the number of transponders 30 that can be accommodated per first multiplexing / demultiplexing unit 11 or increasing the scale of the configuration of the first multiplexing / demultiplexing unit 11.

[0120] <Third embodiment> An optical transmission device 10c (not shown) may be configured by combining the configuration of the optical transmission device 10a in the first embodiment and the configuration of the optical transmission device 10b in the second embodiment. This configuration makes it possible to realize the drop and add functions of optical signals for both upstream traffic from the transponder 30 to the network side and downstream traffic from the network side to the transponder 30. This makes it possible to perform electrical processing for both upstream and downstream signals.

[0121] As described above, the optical transmission device 10c according to the third embodiment of the present invention includes the second multiplexing / demultiplexing unit 13 (the drop function unit (upstream) 13p and the add function unit (upstream) 13q, and the drop function unit (downstream) 13r and the add function unit (downstream) 13s) arranged to sandwich the electrical processing unit 20. With this configuration, the optical transmission device 10c according to the third embodiment does not need to provide an add port and a drop port at the transponder-side port of the first multiplexing / demultiplexing unit 11, as in the conventional optical transmission device 10m shown in FIG. 1 and the conventional optical transmission device 10n shown in FIG. 2, for example.

[0122] As a result, the optical transmission device 10c in the third embodiment can perform electrical processing on the optical signals of upstream traffic and downstream traffic without reducing the number of transponders 30 that can be accommodated per first multiplexing / demultiplexing unit 11 or increasing the scale of the configuration of the first multiplexing / demultiplexing unit 11.

[0123] According to the above-described embodiment, the optical transmission device is a device that transmits optical signals between a communication terminal device and a network without converting them into electrical signals. For example, the optical transmission device is the optical transmission device 10a in the embodiment, and the communication terminal device is the transponder 30 in the embodiment. The optical transmission device includes a plurality of multiplexing / demultiplexing units, a plurality of wavelength multiplexing / demultiplexing units, an upstream signal demultiplexing unit, and an upstream signal multiplexing unit. For example, the multiplexing / demultiplexing unit is the first multiplexing / demultiplexing unit 11 in the embodiment, the wavelength multiplexing / demultiplexing unit is the wavelength multiplexing / demultiplexing unit 12 in the embodiment, the upstream signal demultiplexing unit is the extraction function unit (for upstream) 13p in the embodiment, and the upstream signal multiplexing unit is the addition function unit (for upstream) 13q in the embodiment.

[0124] The multiplexing / demultiplexing unit inputs and outputs optical signals to and from a communication terminal device connected to the device itself. The wavelength multiplexing / demultiplexing unit inputs and outputs optical signals to and from a network connected to the device itself. The upstream signal demultiplexing unit outputs the upstream optical signal output from the multiplexing / demultiplexing unit to an electrical processing unit that performs predetermined electrical processing on the optical signal. For example, the electrical processing unit is electrical processing unit 20 in the embodiment, and the optical signal of the upstream signal is upstream traffic in the embodiment. The upstream signal multiplexing unit outputs the upstream optical signal that has been electrically processed by the electrical processing unit to a predetermined wavelength multiplexing / demultiplexing unit.

[0125] The optical transmission device may further include a downstream signal demultiplexing unit and a downstream signal multiplexing unit. For example, the downstream signal demultiplexing unit is the extraction function unit (for downstream) 13r in the embodiments, and the downstream signal multiplexing unit is the addition function unit (for downstream) 13s in the embodiments. The downstream signal demultiplexing unit outputs the downstream optical signal output from the wavelength multiplexing / demultiplexing unit to an electrical processing unit. For example, the downstream optical signal is downstream traffic in the embodiments. The downstream signal multiplexing unit outputs the downstream optical signal that has been electrically processed by the electrical processing unit to a predetermined multiplexing / demultiplexing unit.

[0126] In the above optical transmission device, the upstream signal demultiplexing section and the upstream signal multiplexing section may be configured to include a fiber cross connect (FXC) and wavelength multiplexing / demultiplexing means.

[0127] In the above optical transmission device, the wavelength multiplexer / demultiplexer may be configured to include a wavelength cross connect (WXC).

[0128] Furthermore, according to the above-described embodiment, the optical transmission device is a device that transmits optical signals between a communication terminal device and a network without converting them into electrical signals. For example, the optical transmission device is the optical transmission device 10b in the embodiment, and the communication terminal device is the transponder 30 in the embodiment. The optical transmission device includes a plurality of multiplexing / demultiplexing units, a plurality of wavelength multiplexing / demultiplexing units, a downstream signal demultiplexing unit, and a downstream signal multiplexing unit. For example, the multiplexing / demultiplexing unit is the first multiplexing / demultiplexing unit 11 in the embodiment, the wavelength multiplexing / demultiplexing unit is the wavelength multiplexing / demultiplexing unit 12 in the embodiment, the downstream signal demultiplexing unit is the extraction function unit (for downstream) 13r in the embodiment, and the downstream signal multiplexing unit is the insertion function unit (for downstream) 13s in the embodiment.

[0129] The multiplexing / demultiplexing unit inputs and outputs optical signals to and from a communication terminal device connected to the device itself. The wavelength multiplexing / demultiplexing unit inputs and outputs optical signals to and from a network connected to the device itself. The downstream signal demultiplexing unit outputs the downstream optical signal output from the wavelength multiplexing / demultiplexing unit to an electrical processing unit that performs predetermined electrical processing on the optical signal. For example, the electrical processing unit is electrical processing unit 20 in the embodiment, and the downstream optical signal is downstream traffic in the embodiment. The downstream signal multiplexing unit outputs the downstream optical signal that has been electrically processed by the electrical processing unit to a predetermined multiplexing / demultiplexing unit.

[0130] In the above optical transmission device, the downstream signal demultiplexing section and the downstream signal multiplexing section may be configured to include a fiber cross connect (FXC) and wavelength multiplexing / demultiplexing means.

[0131] The optical transmission device 10a, the optical transmission device 10b, and the optical transmission device 10c in the above-described embodiments may be partially or entirely implemented by a computer. In this case, a program for implementing the functions may be recorded on a computer-readable recording medium, and the program may be loaded into a computer system and executed. Note that the term "computer system" here includes hardware such as an OS and peripheral devices. Furthermore, the term "computer-readable recording medium" refers to portable media such as a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, and a storage device such as a hard disk built into a computer system.

[0132] Furthermore, the term "computer-readable recording medium" may include a medium that dynamically stores a program for a short period of time, such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, or a medium that stores a program for a fixed period of time, such as a volatile memory within a computer system that serves as a server or client in such a case. The program may also be one that realizes part of the above-mentioned functions, or one that can realize the above-mentioned functions in combination with a program already stored in the computer system, or one that can be realized using a programmable logic device such as an FPGA (Field Programmable Gate Array).

[0133] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention. [Explanation of symbols]

[0134] 10a, 10b, 10c, 10m, 10n...optical transmission device, 11...first multiplexing / demultiplexing unit (multiplexing / demultiplexing unit), 12...wavelength multiplexing / demultiplexing unit, 13...second multiplexing / demultiplexing unit, 13p...drop function unit (for upstream), 13q...insertion function unit (for upstream), 13r...drop function unit (for downstream), 13s...insertion function unit (for downstream), 19...control unit, 20...electrical processing unit, 30...transponder, 90...optical transmission device, 91...multiplexing / demultiplexing unit, 92...wavelength multiplexing / demultiplexing unit, 99...control unit, 100a, 100b, 100m, 100n...optical transmission system

Claims

1. An optical transmission device that transmits optical signals between a communication terminal device and a network without converting them into electrical signals, a plurality of multiplexing / demultiplexing units for inputting and outputting optical signals to and from the communication terminal devices connected to the device itself; a plurality of wavelength multiplexing / demultiplexing units for inputting and outputting optical signals to and from a network connected to the device; an upstream signal demultiplexing unit that outputs the upstream optical signal output from the multiplexing / demultiplexing unit to an electrical processing unit that performs predetermined electrical processing on the optical signal; an upstream signal multiplexing unit that outputs the upstream optical signal that has been electrically processed by the electrical processing unit to a predetermined wavelength multiplexing / demultiplexing unit; An optical transmission device comprising:

2. a downstream signal demultiplexing unit that outputs the downstream optical signal output from the wavelength multiplexing / demultiplexing unit to the electrical processing unit; a downstream signal multiplexing unit that outputs the downstream optical signal that has been electrically processed by the electrical processing unit to a predetermined multiplexing / demultiplexing unit; The optical transmission device according to claim 1 , further comprising:

3. The upstream signal demultiplexing unit and the upstream signal multiplexing unit are configured to include a fiber cross connect and a wavelength multiplexing / demultiplexing means.

3. The optical transmission device according to claim 1.

4. The wavelength multiplexing / demultiplexing unit includes a wavelength cross connect.

3. The optical transmission device according to claim 1.

5. An optical transmission device that transmits optical signals between a communication terminal device and a network without converting them into electrical signals, a plurality of multiplexing / demultiplexing units for inputting and outputting optical signals to and from the communication terminal devices connected to the device itself; a plurality of wavelength multiplexing / demultiplexing units for inputting and outputting optical signals to and from a network connected to the device; a downstream signal demultiplexing unit that outputs the downstream optical signal output from the wavelength multiplexing / demultiplexing unit to an electrical processing unit that performs predetermined electrical processing on the optical signal; a downstream signal multiplexing unit that outputs the downstream optical signal that has been electrically processed by the electrical processing unit to a predetermined multiplexing / demultiplexing unit; An optical transmission device comprising:

6. The downstream signal demultiplexing unit and the downstream signal multiplexing unit each include a fiber cross connect and a wavelength multiplexing / demultiplexing means.

6. The optical transmission device according to claim 5.

7. An optical transmission method for transmitting an optical signal between a communication terminal device and a network without converting it into an electrical signal, comprising: a plurality of multiplexing / demultiplexing steps in which a multiplexing / demultiplexing unit inputs and outputs optical signals to and from the communication terminal device connected to the device itself; a plurality of wavelength multiplexing / demultiplexing steps in which a wavelength multiplexing / demultiplexing unit inputs and outputs optical signals to and from a network connected to the device; an upstream signal demultiplexing step in which the upstream signal demultiplexing unit outputs the upstream optical signal output from the multiplexing / demultiplexing unit to an electrical processing unit that performs predetermined electrical processing on the optical signal; an upstream signal multiplexing step in which an upstream signal multiplexing unit outputs the upstream optical signal, which has been electrically processed by the electrical processing unit, to a predetermined wavelength multiplexing / demultiplexing unit; An optical transmission method comprising:

8. An optical transmission method for transmitting an optical signal between a communication terminal device and a network without converting it into an electrical signal, comprising: a plurality of multiplexing / demultiplexing steps in which a multiplexing / demultiplexing unit inputs and outputs optical signals to and from the communication terminal device connected to the device itself; a plurality of wavelength multiplexing / demultiplexing steps in which a wavelength multiplexing / demultiplexing unit inputs and outputs optical signals to and from a network connected to the device; a downstream signal demultiplexing step in which a downstream signal demultiplexing unit outputs the downstream optical signal output from the wavelength multiplexing / demultiplexing unit to an electrical processing unit that performs predetermined electrical processing on the optical signal; a downstream signal multiplexing step in which a downstream signal multiplexing unit outputs the downstream optical signal, which has been subjected to the electrical processing by the electrical processing unit, to a predetermined multiplexing / demultiplexing unit; An optical transmission method comprising:

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