Optical communication device and optical communication method

Abstract

This optical communication device comprises: a connection switching unit that connects a first communication port connected to a first communication device belonging to the local site of this optical communication device to a second communication port connected to a second communication device belonging to said local site, a third communication port connected to a third communication device belonging to another site, or a fourth communication port connected to an electric processing unit that implements an electric processing of reproduction and relay with respect to a signal that is to be transferred to a fourth communication device belonging to said other site; and a control unit that controls the connection switching of communication ports by the connection switching unit on the basis of the site to which a communication device that is to communicate with the first communication device belongs and of whether the electric processing is necessary or not.

Description

[Technical field]

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

[0002] Conventionally, reconfigurable optical add / drop multiplexers (ROADMs) have been used to connect multiple locations and build efficient networks (see, for example, Non-Patent Document 1). ROADMs are devices that operate ultra-high-speed, large-capacity transmission networks by combining wavelength multiplexing and path management technologies.

[0003] Fig. 12 is a diagram showing an example of the overall configuration of a conventional optical communication device using ROADM. As shown in Fig. 12, the conventional optical communication device includes a transponder unit, a switch unit, a signal multiplexing / demultiplexing unit, an internal amplifier unit, a wavelength multiplexing / demultiplexing unit, and an amplifier unit.

[0004] The configuration of each functional unit of a conventional optical communication device for upstream communication is as follows. First, the transponder unit performs electrical processing on a signal received from a subscriber device using a transponder, and outputs the signal to the switch unit at a specified wavelength. The switch unit transfers the signal input from the transponder unit to a desired path. The signal multiplexing / demultiplexing unit multiplexes signals transferred from multiple switches in the switch unit, and outputs the multiplexed signal to the internal amplifier unit. In order to compensate for losses occurring in the signal multiplexing / demultiplexing unit, the internal amplifier unit amplifies the signal power, and outputs the amplified signal to the wavelength multiplexing / demultiplexing unit. The wavelength multiplexing / demultiplexing unit multiplexes multiple signals input from the signal multiplexing / demultiplexing unit, and outputs the multiplexed signal to the amplifier unit. The amplifier unit amplifies the signal input from the wavelength multiplexing / demultiplexing unit, and outputs the amplified signal to the transmission path side.

[0005] The configuration of each functional unit of a conventional optical communication device for downstream communication is as follows. First, the amplifier unit amplifies a signal received from the transmission line side, and outputs the amplified signal to the wavelength multiplexing / demultiplexing unit. The wavelength multiplexing / demultiplexing unit outputs the signal input from the amplifier unit to the other line or to the internal amplifier unit. The internal amplifier unit amplifies the signal input from the wavelength multiplexing / demultiplexing unit, and outputs the amplified signal to the signal multiplexing / demultiplexing unit. The signal multiplexing / demultiplexing unit distributes the signal input from the internal amplifier unit, and outputs the distributed signal to all switches in the switch unit. In order to receive the desired signal, each switch in the switch unit switches the signal multiplexing / demultiplexing unit to which it is connected, and outputs the received signal to the transponder unit. The transponder unit performs electrical processing on the signal input from the switch unit using a transponder, and transmits the signal to the subscriber device.

[0006] Generally, the process of extracting a signal of a given wavelength from an input signal is performed in a transponder unit. Generally, a switch has a configuration in which input and output are one to M (M is the number of directions, an arbitrary natural number). The wavelength multiplexing / demultiplexing unit is configured, for example, using a plurality of WSSs (Wavelength Selective Switches). The wavelength multiplexing / demultiplexing unit outputs, from among downstream signals input to the WSS from the transmission line side, signals of wavelengths addressed to subscriber devices belonging to the same base as the own device, to a port connected to the internal amplifier unit. The wavelength multiplexing / demultiplexing unit also outputs signals of wavelengths addressed to subscriber devices belonging to other bases different from the base to which the own device belongs, to a port connected to a WSS of a path to the other base. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] Thierry Zami, Bruno Lavigne, “Benefit of pure NxM WSS for optical multiflow application”, OFC / NFOEC Technical Digest, Optical Society of America, 2013 Summary of the Invention [Problem to be solved by the invention]

[0008] In a conventional optical communication device using the above-mentioned ROADM, even when communication is to be performed between subscriber devices under the same ROADM (i.e., within the same base), a signal transmitted from one subscriber device always exits once in the optical communication device to a path different from the destination subscriber device (i.e., the path to the transmission path side in FIG. 12). Therefore, the above-mentioned conventional optical communication device alone cannot transfer a signal from one subscriber device to another subscriber device under the same ROADM (hereinafter referred to as "loopback communication").

[0009] Therefore, when communication is required between subscriber devices under the same ROADM, a new switch capable of processing electrical signals of Layer 2 or higher must be installed between the optical communication device and the subscriber device. However, when a new switch is installed in this way, there is a problem that the cost of the device increases. Furthermore, in this case, even signals addressed to subscriber devices belonging to other bases (i.e., communication signals that are not loopback communication) must pass through the newly installed switch. This causes a problem that communication delays increase.

[0010] In view of the above circumstances, an object of the present invention is to provide an optical communication device and an optical communication method that can suppress increases in device costs and communication delays in both communications within the same site and communications between different sites. [Means for solving the problem]

[0011] One aspect of the present invention is an optical communication device comprising a connection switching unit that connects a first communication port connected to a first communication device belonging to the own base to a second communication port connected to a second communication device belonging to the own base, a third communication port connected to a third communication device belonging to another base, or a fourth communication port connected to an electrical processing unit that performs electrical processing for regeneration and relay on a signal transmitted to a fourth communication device belonging to the other base, and a control unit that controls the connection switching of the communication ports by the connection switching unit based on the base to which a communication device that communicates with the first communication device belongs and whether the electrical processing is required.

[0012] Moreover, one aspect of the present invention is an optical communication device comprising a plurality of connection switching units that connect a first communication port to a second communication port, a third communication port, or a fourth communication port; a signal multiplexing / demultiplexing unit that multiplexes signals output from the plurality of connection switching units, and connects the first communication port to a first communication device belonging to the own base, connects the second communication port to a second communication device belonging to the own base, connects the third communication port to a third communication device belonging to another base, and connects the fourth communication port to an electrical processing unit that performs electrical processing for regeneration and relay on a signal to be transmitted to a fourth communication device belonging to the other base; and a control unit that controls the connection switching of the communication ports by the connection switching units based on the base to which a communication device that communicates with the first communication device belongs and whether the electrical processing is required.

[0013] Moreover, one aspect of the present invention is an optical communication method having a connection switching step of connecting a first communication port connected to a first communication device belonging to the own base to a second communication port connected to a second communication device belonging to the own base, a third communication port connected to a third communication device belonging to another base, or a fourth communication port connected to an electrical processing unit that performs electrical processing for regeneration and relay on a signal transmitted to a fourth communication device belonging to the other base, and a control step of controlling the connection switching of the communication port in the connection switching step based on the base to which a communication device that communicates with the first communication device belongs and whether the electrical processing is required.

[0014] Moreover, one aspect of the present invention is an optical communication method having a connection switching step in which a plurality of connection switching units respectively connect a first communication port to a second communication port, a third communication port, or a fourth communication port; a signal multiplexing / demultiplexing step in which signals output from the plurality of connection switching units respectively are multiplexed, and the first communication port is connected to a first communication device belonging to the own base, the second communication port is connected to a second communication device belonging to the own base, the third communication port is connected to a third communication device belonging to another base, and the fourth communication port is connected to an electrical processing unit that performs electrical processing for regeneration and relay on a signal to be transmitted to a fourth communication device belonging to another base; and a control step in which the connection switching of the communication ports in the connection switching step is controlled based on the base to which a communication device that communicates with the first communication device belongs and whether the electrical processing is required. Effect of the Invention

[0015] According to the present invention, it is possible to suppress increases in device costs and communication delays in both communications within the same location and communications between different locations. [Brief description of the drawings]

[0016] [Figure 1] 1 is an overall configuration diagram of an optical communication device 1 according to a first embodiment of the present invention. [Diagram 2] 2 is a diagram for explaining details of a switching process by a switch unit 20 of the optical communication device 1 in the first embodiment of the present invention. FIG. [Diagram 3] 4 is a flowchart showing an operation of the optical communication device 1 in the first embodiment of the present invention. [Figure 4] FIG. 2 is an overall configuration diagram of an optical communication device 1a according to a first modified example of the first embodiment of the present invention. [Diagram 5] FIG. 11 is a diagram for explaining details of a switching process by a switch unit 20b of an optical communication device 1b in a second modified example of the first embodiment of the present invention. [Figure 6] FIG. 11 is an overall configuration diagram of an optical communication device 1c according to a second embodiment of the present invention. [Figure 7]FIG. 11 is a diagram for explaining details of a switching process performed by a switch unit 20c of an optical communication device 1c according to a second embodiment of the present invention. [Figure 8] 10 is a flowchart showing an operation of an optical communication device 1c according to the second embodiment of the present invention. [Figure 9] FIG. 11 is an overall configuration diagram of an optical communication device 1d according to a third embodiment of the present invention. [Figure 10] FIG. 11 is a diagram for explaining details of a switching process performed by a switch unit 20d of an optical communication device 1d according to a third embodiment of the present invention. [Figure 11] 13 is a flowchart showing an operation of an optical communication device 1d according to the third embodiment of the present invention. [Figure 12] FIG. 1 is a diagram illustrating an example of the overall configuration of a conventional optical communication device using a ROADM. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0018] <First embodiment> The optical communication device 1 according to the first embodiment of the present invention will now be described.

[0019] [Configuration of optical communication device] Fig. 1 is an overall configuration diagram of an optical communication device 1 in a first embodiment of the present invention. As shown in Fig. 1, the optical communication device 1 includes a wavelength tunable filter section 10, a switch section 20, a signal multiplexing / demultiplexing section 30, an internal amplifier section 40, a wavelength multiplexing / demultiplexing section 50, an amplifier section 60, a wavelength management control section 70, and an electrical processing section 80.

[0020] The configuration of each functional unit of the optical communication device 1 of the first embodiment in upstream communication is as follows.

[0021] The tunable filter unit 10 receives a signal transmitted from a subscriber device and outputs the received signal to the switch unit 20 at a predetermined wavelength.

[0022] The switch unit 20 receives the input of the signal output from the wavelength tunable filter unit 10. The switch unit 20 includes a plurality of switches. Each switch in the switch unit 20 transfers the input signal to a desired path. The desired path here refers to a path to a desired coupler in the signal multiplexing / demultiplexing unit 30, a path to the wavelength management control unit 70, or a path to the electrical processing unit 80.

[0023] The signal demultiplexing unit 30 includes a plurality of couplers. The plurality of couplers of the signal demultiplexing unit 30 receive inputs of signals transferred from the plurality of switches of the switch unit 20. The plurality of couplers of the signal demultiplexing unit 30 multiplex the plurality of input signals. The signal demultiplexing unit 30 outputs the multiplexed signal to the internal amplifier unit 40.

[0024] The internal amplifier unit 40 receives the input of the signal output from the signal multiplexing / demultiplexing unit 30. The internal amplifier unit 40 amplifies the signal power to compensate for loss caused by signal multiplexing by the signal multiplexing / demultiplexing unit 30. The internal amplifier unit 40 outputs the amplified signal to the wavelength multiplexing / demultiplexing unit 50.

[0025] The wavelength multiplexing / demultiplexing unit 50 receives a plurality of input signals from the internal amplifier unit 40. The wavelength multiplexing / demultiplexing unit 50 multiplexes the input plurality of signals. The wavelength multiplexing / demultiplexing unit 50 outputs the multiplexed signal to the amplifier unit 60.

[0026] The amplifier unit 60 receives the input of the signal output from the wavelength multiplexing / demultiplexing unit 50. The amplifier unit 60 amplifies the input signal. The amplifier unit 60 outputs the amplified signal to the transmission line side.

[0027] The wavelength management control unit 70 changes the wavelength of a signal transmitted from a subscriber device. The wavelength management control unit 70 issues a wavelength instruction to the subscriber device, for example, by using an auxiliary management and control channel (AMCC). The AMCC is one of the wavelength management controls that is a main function of a Ph-GW (Photonic Gateway). Specifically, the wavelength management control unit 70 issues a wavelength instruction by, for example, transmitting a wavelength control instruction signal indicating an instruction to change the wavelength of the signal to the subscriber device.

[0028] The electrical processing unit 80 includes a plurality of transponders. The electrical processing unit 80 receives an input of a signal output from a switch of the switch unit 20. The electrical processing unit 80 performs electrical processing on the input signal for regenerative relay. The electrical processing for regenerative relay is, for example, a process of once demodulating the input signal, modulating it again at a different frequency, and outputting it. The electrical processing unit 80 outputs the electrically processed signal to a switch other than the switch of the switch unit 20 that is the input source.

[0029] The configuration of each functional unit of the optical communication device 1 of the first embodiment in downstream communication is as follows.

[0030] The amplifier unit 60 receives an input of a signal arriving from the transmission line side. The amplifier unit 60 amplifies the input signal. The amplifier unit 60 outputs the amplified signal to the wavelength multiplexing / demultiplexing unit 50.

[0031] The wavelength multiplexing / demultiplexing unit 50 receives an input of a signal output from the amplifier unit 60. The wavelength multiplexing / demultiplexing unit 50 demultiplexes the input signal. The wavelength multiplexing / demultiplexing unit 50 outputs the demultiplexed signal to the other path or to the internal amplifier unit 40.

[0032] The internal amplifier unit 40 receives the input of the signal output from the wavelength multiplexing / demultiplexing unit 50. The internal amplifier unit 40 amplifies the input signal. The internal amplifier unit 40 outputs the amplified signal to the signal multiplexing / demultiplexing unit 30.

[0033] The signal multiplexing / demultiplexing unit 30 receives the input of the signal output from the internal amplifier unit 40. The signal multiplexing / demultiplexing unit 30 distributes the input signal. The signal multiplexing / demultiplexing unit 30 outputs the distributed signal to all the switches in the switch unit 20.

[0034] Each switch of the switch unit 20 accepts input of a signal output from the signal multiplexing / demultiplexing unit 30. In order to receive a desired signal, each switch of the switch unit 20 switches the port to select the signal multiplexing / demultiplexing unit 30 to which it is connected. Each switch of the switch unit 20 transmits the input signal to a subscriber device via the wavelength tunable filter unit 10, a transponder, or an electrical processing unit 80 and a switch at the next stage.

[0035] Hereinafter, the flow of signals will be described with reference to Fig. 2. Fig. 2 is a diagram for explaining details of the switching process by the switch unit 20 of the optical communication device 1 in the first embodiment of the present invention.

[0036] As shown in FIG. 2, each switch (switch #A, switch #B, switch #1, and switch #2) of switch section 20 is a switch having an input / output configuration of 1:M (M is any natural number) that connects one port to any of multiple ports.

[0037] For example, in FIG. 2, switch #A is a switch having a 1:4 input / output configuration that connects a port (first communication port) connected to a path leading to subscriber device A via the wavelength tunable filter unit 10 to either port (1) (third communication port) connected to the signal multiplexing / demultiplexing unit 30, port (2) connected to the wavelength management control unit 70, port (3) (fourth communication port) connected to the electrical processing unit 80, or port (4) (second communication port) for return communication connected to switch #B.

[0038] When subscriber device A communicates with subscriber device B at the same location, the port of switch #A is switched to (4). On the other hand, when subscriber device A connects to subscriber device C (not shown) at a different location, the port of switch #A is switched to (1) or (3). Whether the port of switch #A is switched to (1) or (3) is determined depending on whether regeneration is required. This determination is made by, for example, the wavelength management control unit 70.

[0039] Specifically, for example, when the distance between subscriber device A and subscriber device C (not shown) is short and regenerative repeating is not required, the port of switch #A is switched to (1). Conversely, for example, when the distance between subscriber device A and subscriber device C (not shown) is long and regenerative repeating is required, the port of switch #A is switched to (3). In this case, the signal is subjected to electrical processing for regenerative repeating by a transponder (transponder #A in FIG. 2) in electrical processing unit 80, and then output to switch #1, and then transferred to a path toward subscriber device C (not shown).

[0040] In this way, the optical communication device 1 in the first embodiment is configured to perform electrical processing (e.g., processing for regenerative relay by a transponder) by the electrical processing unit 80 when necessary, rather than being required for communication within the same base and communication between different bases. With this configuration, the optical communication device 1 in the first embodiment can omit the performance of electrical processing when not necessary, thereby suppressing an increase in communication delay.

[0041] On the other hand, in downstream communication, in the prior art, the process of extracting a signal of an arbitrary wavelength was performed in a transponder unit. In contrast, the optical communication device 1 in the first embodiment does not require electrical processing by the transponder unit. As shown in FIG. 1, the optical communication device 1 in the first embodiment includes a wavelength-tunable filter unit 10 that extracts a signal of an arbitrary wavelength instead of a transponder unit. For example, when a subscriber device performs digital coherent communication similar to a transponder, the process of extracting a signal of an arbitrary wavelength can be performed in the subscriber device, so the wavelength-tunable filter unit 10 does not need to be installed.

[0042] In addition, in the conventional technology, after the wavelength of the signal used in the signal on the transmission line side is assigned, the transponder unit sets the wavelength of the signal to be output to the transmission line side to the assigned wavelength. Therefore, in the conventional technology, the wavelength of the signal used in the signal between the transponder unit and the subscriber device can be any wavelength, regardless of the wavelength of the signal used in the signal on the transmission line side.

[0043] On the other hand, in the optical communication device 1 in the first embodiment, since electrical processing in the transponder section is not essential, the signal does not necessarily pass through the transponder. Therefore, in the optical communication device 1 in the first embodiment, since the signal may not pass through the transponder, it is not possible to configure the wavelength to be set by the transponder as in the conventional technology. Therefore, in the optical communication device 1 in the first embodiment, the wavelength of the signal transmitted from the subscriber device must be the same as the wavelength used by the signal on the transmission line side.

[0044] In the optical communication device 1 in the first embodiment, for example, when changing the wavelength of a signal transmitted from the subscriber device A, the port of the switch #A shown in Fig. 2 is switched to (2). This causes the wavelength management control unit 70 to transmit a wavelength control instruction signal to the subscriber device, and a wavelength instruction is issued. The wavelength management control unit 70 issues a wavelength instruction to the subscriber device using, for example, AMCC or the like.

[0045] Unlike the conventional technology described above, in the optical communication device 1 of the first embodiment, the switch #A and the switch #B need to connect not only to the desired coupler of the signal multiplexing / demultiplexing unit 30 but also to the wavelength management control unit 70, the electrical processing unit 80, and the return communication. Therefore, in the optical communication device 1 of the first embodiment, it is necessary to increase the number of ports of each switch or reduce the number of connection directions compared to the conventional technology described above.

[0046] 2 in the optical communication device 1 in the first embodiment, unlike the switches #A and #B, only needs to switch the communication path through which the signal electrically processed by the transponder of the electrical processing unit 80 is transmitted to a port connected to a desired path. As described above, the role of the switches #1 and #2 is different from that of the switches #A and #B, and the number of ports can be changed.

[0047] In other words, if the switches that are directly connected to subscriber devices (switches #A and #B in FIG. 2) are switches that are connected via ports having an input / output configuration of 1:m (m is any natural number), and the switches that are not directly connected to subscriber devices but are only directly connected to electrical processing units (switches #1 and #2 in FIG. 2) are switches that are connected via ports having an input / output configuration of 1:n (n is any natural number), then the values ​​of m and n can be different from each other.

[0048] Unlike the conventional technology described above, in the optical communication device 1 in the first embodiment, the signal multiplexing / demultiplexing unit 30 is connected not only to the switch #A and the switch #B, but also to the switch #1 and the switch #2, as described above. Therefore, in order to prevent a decrease in the number of subscriber devices that can be accommodated by providing the switch #1 and the switch #2 with different roles, the number of couplers in the signal multiplexing / demultiplexing unit 30 or the number of ports per coupler may be increased. When the number of couplers in the signal multiplexing / demultiplexing unit 30 is increased, it is necessary to increase the number of amplifiers in the internal amplifier unit 40 and the number of ports of the wavelength multiplexing / demultiplexing unit 50 as well.

[0049] 1, it is assumed that upstream and downstream communications are performed on a single fiber on the transmission line side, but the upstream and downstream communications may be performed on different fibers. In this case, the entire section from the switch unit 20 to the amplifier unit 60 must be provided with separate components for upstream and downstream communications.

[0050] In addition, in the optical communication device 1 in the first embodiment, there is a risk that a subscriber device that is not permitted to communicate may connect to the switch unit 20 without permission. In this case, a signal transmitted by a subscriber device that is not permitted to communicate may interfere with signals transmitted and received by other subscriber devices that are permitted to communicate. Such a risk can be addressed by adding to the optical communication device 1 a configuration in which a port of the switch to which a subscriber device that is not permitted to communicate can be connected without permission is switched to an unused port that is not connected to anything, a configuration in which the power supply of the switch is turned off, or a configuration in which a wavelength tunable filter is installed in the upstream direction to prevent unauthorized signals from flowing.

[0051] The optical communication device 1 in the first embodiment described above can be configured using ROADM hardware. The wavelength management control unit 70 can be implemented in software on the same hardware as the switch and transponder control units, which are also provided in conventional optical communication devices using ROADM hardware. The electrical processing unit 80 can also be implemented in software on the same hardware as the conventional transponder control unit. In this way, by utilizing the ROADM technology used in conventional optical transmission devices that are widely used in network construction these days, the optical communication device 1 in the first embodiment can provide communication with lower latency while suppressing increases in device costs.

[0052] In addition, the optical communication device 1 in the first embodiment can be used in combination with conventional technology. For example, the optical communication device 1 in the first embodiment can simultaneously accommodate a subscriber device (e.g., subscriber device D shown in FIG. 1) that performs conventional communication via a transponder like the subscriber device D shown in FIG. 1, and a subscriber device (e.g., subscriber device A and subscriber device B shown in FIG. 1) that performs communication that does not require electrical processing (communication that does not require passing through a transponder).

[0053] That is, when introducing the technology provided in the optical communication device 1 in the first embodiment, it is not necessary to completely replace the existing optical communication device that has already been installed with the new optical communication device 1. Therefore, for example, even if the subscriber device D shown in Fig. 1 is in operation, it is possible to add a subscriber device (for example, subscriber device A and subscriber device B shown in Fig. 1) that performs communication that does not require electrical processing (communication that does not require passing through a transponder) later by simply installing a separate switch without affecting the service in operation.

[0054] The wavelength management control unit 70 of the optical communication device 1 in the first embodiment may be integrated with a control unit that controls the wavelength of a transponder included in a conventional optical communication device. In this case, the wavelength management control unit 70 can centrally manage the wavelengths of the transponder and the wavelengths of the subscriber device. For example, such centralized management is required when there is an overlap between the range of wavelengths that the transponder can use and the range of wavelengths that the subscriber device can use.

[0055] Alternatively, the wavelength management control unit 70 of the optical communication device 1 in the first embodiment may be configured to be separated from a control unit that controls the wavelength of a transponder included in a conventional optical communication device. In this case, the range of wavelengths available for the transponder and the range of wavelengths available for the subscriber device must be separated in advance.

[0056] Furthermore, a signal transmitted from a subscriber device that requires regeneration and repeating passes through a transponder (electrical processing unit 80) once in the optical communication device 1 before exiting to the transmission line side, as shown in Fig. 2. In such a case, since the signal between the subscriber device and the transponder is not multiplexed with other signals, a configuration may be adopted in which any wavelength can be assigned to the signal transmitted from the subscriber device. This allows the optical communication device 1 in the first embodiment to make effective use of wavelengths.

[0057] [Operation of optical communication device] The operation of the optical communication device 1 in the first embodiment will be described. Hereinafter, the operation of the optical communication device 1 in upstream communication will be described as an example. Fig. 3 is a flowchart showing the operation of the optical communication device 1 in the first embodiment of the present invention.

[0058] First, the tunable filter unit 10 receives a signal transmitted from, for example, the subscriber device A shown in Fig. 1 (step S101). The tunable filter unit 10 outputs the received signal to the switch unit 20 at a predetermined wavelength.

[0059] Next, the switch unit 20 accepts the input of the signal output from the wavelength-variable filter unit 10. Each switch of the switch unit 20 transfers the input signal to the desired route. If the input signal is to be transferred to a subscriber device B in the same base, for example, as shown in FIG. 1 (step S102: YES), the switch unit 20 switches the port of switch #A in FIG. 2 to (4) (step S103). As a result, the signal is output to switch #B in FIG. 2.

[0060] Switch #B of switch unit 20 accepts the input of the signal output from switch #A. Switch #B transmits the input signal to subscriber device B that exists at the same site (step S104). This completes the operation of optical communication device 1 shown in the flowchart of FIG. 3.

[0061] On the other hand, if the input signal is a signal to be transferred to a subscriber device C (not shown) located at a different site (step S102: NO) and the distance between the subscriber device A and the subscriber device C (not shown) is equal to or greater than a predetermined distance (i.e., a distance that requires electrical processing for regenerative relay) (step S103: YES), the switch unit 20 switches the port of switch #A shown in Fig. 2 to (3) (step S106).

[0062] In this case, the signal is output to the electrical processing unit 80. The electrical processing unit 80 performs electrical processing on the input signal for regenerative relay (step S107). The signal that has been electrically processed is output to the signal multiplexing / demultiplexing unit 30 via switch #1 of the switch unit 20 shown in FIG.

[0063] On the other hand, if the input signal is a signal to be transferred to a subscriber device C (not shown) located at a different site (step S102: NO) and the distance between the subscriber device A and the subscriber device C (not shown) is shorter than a predetermined distance (i.e., a distance that does not require electrical processing for regeneration and relay) (step S103: NO), the switch unit 20 switches the port of switch #A shown in Fig. 2 to (1) (step S108). As a result, the signal is output to the signal multiplexing / demultiplexing unit 30.

[0064] Next, the signal demultiplexing unit 30 receives the input of the signal output from the switch unit 20. The signal demultiplexing unit 30 multiplexes the input signal with another signal output from the switch unit 20 (step S109). The signal demultiplexing unit 30 outputs the multiplexed signal to the internal amplifier unit 40.

[0065] Next, the internal amplifier unit 40 receives the input of the signal output from the signal multiplexing / demultiplexing unit 30. The internal amplifier unit 40 amplifies the signal power to compensate for loss caused by signal multiplexing by the signal multiplexing / demultiplexing unit 30 (step S110). The internal amplifier unit 40 outputs the amplified signal to the wavelength multiplexing / demultiplexing unit 50.

[0066] Next, the wavelength multiplexing / demultiplexing unit 50 receives an input of a signal output from the internal amplifier unit 40. The wavelength multiplexing / demultiplexing unit 50 multiplexes the input signal with another signal output from the internal amplifier unit 40 (step S111). The wavelength multiplexing / demultiplexing unit 50 outputs the multiplexed signal to the amplifier unit 60.

[0067] Next, the amplifier unit 60 receives the input of the signal output from the wavelength multiplexing / demultiplexing unit 50. The amplifier unit 60 amplifies the input signal. The amplifier unit 60 transmits the amplified signal to a subscriber device at another point (e.g., subscriber device C, not shown) via the transmission path (step S112). This completes the operation of the optical communication device 1 shown in the flowchart of FIG. 3.

[0068] As described above, the optical communication device 1 according to the first embodiment of the present invention can perform return communication. The optical communication device 1 according to the first embodiment uses, for example, a device configuration of ROADM, and can perform communication that does not require electrical processing by a transponder.

[0069] Specifically, the optical communication device 1 in the first embodiment switches the ports of each switch in the switch unit 20 to ports that enable return communication when communication is between subscriber devices in the same ROADM (within the own base). Also, when communication is between a subscriber device in the own base and a subscriber device in another base, the optical communication device 1 in the first embodiment switches the ports of each switch in the switch unit 20 based on whether regeneration is required.

[0070] With such a configuration, the optical communication device 1 in the first embodiment of the present invention can suppress increases in device costs and communication delays in both communications within the same base and communications between different bases.

[0071] <First Modification of the First Embodiment> An optical communication device 1a according to a first modified example of the first embodiment of the present invention will be described below.

[0072] [Configuration of optical communication device] 4 is a diagram showing the overall configuration of an optical communication device 1a according to a first modified example of the first embodiment of the present invention. As shown in FIG. 4, the optical communication device 1a includes a tunable filter section 10, a switch section 20a, a wavelength multiplexing / demultiplexing section 50a, an amplifier section 60, a wavelength management control section 70, and an electrical processing section 80.

[0073] The configuration of each functional unit of the optical communication device 1a according to the first modification of the first embodiment in upstream communication is as follows.

[0074] The tunable filter unit 10 receives a signal transmitted from a subscriber device and outputs the received signal to the switch unit 20a at a predetermined wavelength.

[0075] The switch unit 20a receives the signal output from the wavelength tunable filter unit 10. The switch unit 20a includes a plurality of switches. Each switch in the switch unit 20a transfers the input signal to a desired path. The desired path here refers to a path to the wavelength multiplexing / demultiplexing unit 50a, a path to the wavelength management control unit 70, or a path to the electrical processing unit 80.

[0076] The wavelength multiplexing / demultiplexing unit 50a receives input of signals transferred from each of the multiple switches of the switch unit 20a. The wavelength multiplexing / demultiplexing unit 50a multiplexes the input multiple signals. The wavelength multiplexing / demultiplexing unit 50a outputs the multiplexed signal to the amplifier unit 60.

[0077] The amplifier unit 60 receives the signal output from the wavelength multiplexing / demultiplexing unit 50a, amplifies the input signal, and outputs the amplified signal to the transmission line.

[0078] The wavelength management control unit 70 changes the wavelength of a signal transmitted from a subscriber device. The wavelength management control unit 70 issues a wavelength instruction to the subscriber device, for example, by using AMCC or the like. Specifically, the wavelength management control unit 70 issues a wavelength instruction by, for example, transmitting a wavelength control instruction signal indicating an instruction to change the wavelength of the signal to the subscriber device.

[0079] The electrical processing unit 80 includes a plurality of transponders. The electrical processing unit 80 receives an input of a signal output from a switch of the switch unit 20a. The electrical processing unit 80 performs electrical processing on the input signal for regenerative relay. The electrical processing unit 80 outputs the electrically processed signal to a switch other than the switch of the switch unit 20a that is the input source.

[0080] The configuration of each functional unit of the optical communication device 1a according to the first modification of the first embodiment in downstream communication is as follows.

[0081] The amplifier unit 60 receives an input of a signal arriving from the transmission line side. The amplifier unit 60 amplifies the input signal. The amplifier unit 60 outputs the amplified signal to the wavelength multiplexing / demultiplexing unit 50a.

[0082] The wavelength multiplexing / demultiplexing unit 50a receives the input of the signal output from the amplifier unit 60. The wavelength multiplexing / demultiplexing unit 50a demultiplexes the input signal. The wavelength multiplexing / demultiplexing unit 50a outputs the demultiplexed signal to all of the switches in the switch unit 20a.

[0083] Each switch in the switch unit 20a receives an input of a signal output from the wavelength multiplexing / demultiplexing unit 50a. In order to receive a desired signal, each switch in the switch unit 20a switches the port to switch the wavelength multiplexing / demultiplexing unit 50a to which it is connected. Each switch in the switch unit 20a transmits the input signal to a subscriber device via the wavelength tunable filter unit 10, a transponder, or an electrical processing unit 80 and a switch in the next stage.

[0084] The optical communication device 1 in the first embodiment described above is configured to include a signal multiplexing / demultiplexing unit 30. This is a configuration aimed at increasing the number of subscriber devices that can be accommodated. Also, the optical communication device 1 in the first embodiment described above is configured to include an internal amplifier unit 40. This is a configuration aimed at compensating for signal loss in the signal multiplexing / demultiplexing unit 30 of the optical communication device 1.

[0085] In contrast, in the optical communication device 1a in the first modified example of the first embodiment, the signal multiplexing / demultiplexing unit 30 and the internal amplifier unit 40 are omitted as shown in Fig. 4. Due to such a configuration, the optical communication device 1a in the first modified example of the first embodiment may be able to accommodate a smaller number of subscriber devices than the optical communication device 1 in the above-mentioned first embodiment. However, by being provided with such a configuration, the optical communication device 1a in the first modified example of the first embodiment can further suppress the occurrence of communication delays.

[0086] <Second Modification of the First Embodiment> An optical communication device 1b according to a second modified example of the first embodiment of the present invention will now be described.

[0087] [Configuration of optical communication device] The overall configuration diagram of the optical communication device 1b in the second modified example of the first embodiment is similar to the overall configuration diagram of the optical communication device 1 in the above-mentioned first embodiment shown in Fig. 1, so the description will be omitted. Fig. 5 is a diagram for explaining details of the switching process by the switch unit 20b of the optical communication device 1b in the second modified example of the first embodiment of the present invention.

[0088] In the optical communication device 1 in the first embodiment described above, in the switch #A and the switch #B connecting the subscriber device and each path, separate ports are provided for each of the paths to the wavelength management control unit 70, the path to the electrical processing unit 80, and the path to the turn-back destination subscriber device. That is, in the optical communication device 1 in the first embodiment described above, as shown in Fig. 2, in the switch #A and the switch #B connecting the subscriber device and each path, port (2) connected to the wavelength management control unit 70, port (3) connected to the electrical processing unit 80, and port (4) serving as the path to the turn-back destination subscriber device are provided.

[0089] In contrast, in the optical communication device 1b in the second modified example of the first embodiment, as shown in FIG. 5, only one port (only port (2) in FIG. 5) is added (compared to the conventional technology) to each of the switches #A and #B. The added ports are further connected to other switches (switches #A' and #B' in FIG. 5). These other switches (switches #A' and #B') are configured to switch the ports to connect to a path to the wavelength management control unit 70b, a path to the electrical processing unit 80b, or a path to the return destination subscriber device (from switch #A' to switch #B', or from switch #B' to switch #A').

[0090] With such a configuration, the optical communication device 1b in the second modified example of the first embodiment may have a larger total number of switches in the switch unit 20b than the optical communication device 1 in the above-described first embodiment. However, with such a configuration, the optical communication device 1b in the second modified example of the first embodiment can suppress an increase in the number of ports added to the switch #A and the switch #B (compared to the conventional technology).

[0091] Instead of switch #A' and switch #B', a wavelength multiplexer / demultiplexer such as AWG (Arrayed Waveguide Gratings) / WSS, or a coupler may be used.

[0092] <Second embodiment> An optical communication device 1c according to the second embodiment of the present invention will now be described.

[0093] [Configuration of optical communication device] Fig. 6 is an overall configuration diagram of an optical communication device 1c according to a second embodiment of the present invention. As shown in Fig. 6, the optical communication device 1c includes a tunable filter unit 10, a switch unit 20c, a signal multiplexing / demultiplexing unit 30c, an internal amplifier unit 40, a wavelength multiplexing / demultiplexing unit 50, an amplifier unit 60, a wavelength management control unit 70c, and an electrical processing unit 80c.

[0094] The configuration of each functional unit of the optical communication device 1c of the second embodiment in upstream communication is as follows.

[0095] The tunable filter unit 10 receives a signal transmitted from a subscriber device and outputs the received signal to the switch unit 20c at a predetermined wavelength.

[0096] The switch unit 20c receives the input of the signal output from the wavelength-tunable filter unit 10. The switch unit 20c is configured to include a plurality of switches. Each switch of the switch unit 20c transfers the input signal to a desired path. The desired path here refers to a path to a desired coupler of the signal multiplexing / demultiplexing unit 30c, a path to the wavelength management control unit 70c (via the signal multiplexing / demultiplexing unit 30c), a path to the electrical processing unit 80c (via the signal multiplexing / demultiplexing unit 30c), or a path to a subscriber device that is the destination of return communication (via the signal multiplexing / demultiplexing unit 30c).

[0097] The signal demultiplexing unit 30c includes a plurality of couplers. The plurality of couplers of the signal demultiplexing unit 30c receive inputs of signals transferred from the plurality of switches of the switch unit 20c. The plurality of couplers of the signal demultiplexing unit 30c multiplex the input signals. The signal demultiplexing unit 30c outputs the multiplexed signal to the internal amplifier unit 40.

[0098] Alternatively, the coupler of the signal multiplexing / demultiplexing unit 30c outputs the signal to the wavelength management control unit 70c, the electrical processing unit 80c, or another coupler that provides a route to the subscriber device that is the destination of the return communication.

[0099] The internal amplifier unit 40 receives the signal output from the signal multiplexing / demultiplexing unit 30c. The internal amplifier unit 40 amplifies the signal power to compensate for loss caused by signal multiplexing by the signal multiplexing / demultiplexing unit 30c. The internal amplifier unit 40 outputs the amplified signal to the wavelength multiplexing / demultiplexing unit 50.

[0100] The wavelength multiplexing / demultiplexing unit 50 receives a plurality of input signals from the internal amplifier unit 40. The wavelength multiplexing / demultiplexing unit 50 multiplexes the input plurality of signals. The wavelength multiplexing / demultiplexing unit 50 outputs the multiplexed signal to the amplifier unit 60.

[0101] The amplifier unit 60 receives the input of the signal output from the wavelength multiplexing / demultiplexing unit 50. The amplifier unit 60 amplifies the input signal. The amplifier unit 60 outputs the amplified signal to the transmission line side.

[0102] The wavelength management control unit 70c changes the wavelength of a signal transmitted from a subscriber device. The wavelength management control unit 70 issues a wavelength instruction to the subscriber device, for example, by using AMCC or the like. Specifically, the wavelength management control unit 70c issues a wavelength instruction by, for example, transmitting a wavelength control instruction signal indicating an instruction to change the wavelength of the signal to the subscriber device.

[0103] The electrical processing unit 80c includes at least one transponder. The electrical processing unit 80c receives the input of the signal output from the signal multiplexing / demultiplexing unit 30c. The electrical processing unit 80c performs electrical processing on the input signal for regenerative relay. The electrical processing for regenerative relay is a process in which the input signal is once demodulated, then modulated again at another frequency and output. The electrical processing unit 80c outputs the electrically processed signal to a switch other than the switch of the switch unit 20c that is the input source to the signal multiplexing / demultiplexing unit 30c that received the input of the signal.

[0104] The configuration of each functional unit of the optical communication device 1 of the first embodiment in downstream communication is as follows.

[0105] The amplifier unit 60 receives an input of a signal arriving from the transmission line side. The amplifier unit 60 amplifies the input signal. The amplifier unit 60 outputs the amplified signal to the wavelength multiplexing / demultiplexing unit 50.

[0106] The wavelength multiplexing / demultiplexing unit 50 receives an input of a signal output from the amplifier unit 60. The wavelength multiplexing / demultiplexing unit 50 demultiplexes the input signal. The wavelength multiplexing / demultiplexing unit 50 outputs the demultiplexed signal to the other path or to the internal amplifier unit 40.

[0107] The internal amplifier unit 40 receives the input of the signal output from the wavelength multiplexing / demultiplexing unit 50. The internal amplifier unit 40 amplifies the input signal. The internal amplifier unit 40 outputs the amplified signal to the signal multiplexing / demultiplexing unit 30c.

[0108] The signal demultiplexing unit 30c receives the input of the signal output from the internal amplifier unit. The signal demultiplexing unit 30c distributes the input signal. The signal demultiplexing unit 30 outputs the distributed signal to all the switches of the switch unit 20c.

[0109] Each switch in the switch unit 20c receives an input of a signal output from the signal multiplexing / demultiplexing unit 30c. In order to receive a desired signal, each switch in the switch unit 20c switches the port to switch the signal multiplexing / demultiplexing unit 30c to which it is connected. Each switch in the switch unit 20c transmits the input signal to a subscriber device via the wavelength tunable filter unit 10, a transponder, or an electrical processing unit 80c, a next-stage switch, and a coupler in the signal multiplexing / demultiplexing unit 30c in the next stage.

[0110] Hereinafter, the flow of signals will be described with reference to Fig. 7. Fig. 7 is a diagram for explaining details of the switching process by the switch unit 20c and the signal multiplexing / demultiplexing unit 30c of the optical communication device 1c in the second embodiment of the present invention.

[0111] In the optical communication device 1c in the second embodiment, unlike the optical communication device 1 in the first embodiment described above, the connection to the wavelength management control unit 70c, the connection to the electrical processing unit 80c, and the return communication are performed by the signal multiplexing / demultiplexing unit 30c rather than the switch unit 20c.

[0112] In the optical communication device 1 in the first embodiment described above, as shown in Fig. 2, the wavelength management control unit 70 and the electrical processing unit 80 are connected to the switch #A and the switch #B by separate ports, respectively. On the other hand, in the optical communication device 1c in the second embodiment, as shown in Fig. 7, signals pass through the signal multiplexing / demultiplexing unit 30c between the switch #A and the switch #B and the wavelength management control unit 70c and the electrical processing unit 80c. This allows the wavelength management control unit 70c and the electrical processing unit 80c to be connected to the switch #A and the switch #B by a single port.

[0113] By providing such a configuration, the optical communication device 1c in the second embodiment can reduce the number of ports required in the wavelength management control unit 70c and the electrical processing unit 80c compared to the optical communication device 1 in the above-mentioned first embodiment. However, according to the configuration of the optical communication device 1c in the second embodiment, since it is difficult to simultaneously send different signals due to the above-mentioned configuration, a separate process for avoiding interference by time division or the like is required.

[0114] 7, when subscriber device A communicates with subscriber device B, the port of switch #A is switched to (4). Here, since the coupler has multiple ports, when another subscriber device is connected to that port, subscriber device A can also communicate with that other subscriber device. Thus, unlike the optical communication device 1 in the above-described first embodiment, the optical communication device 1c in the second embodiment allows a certain subscriber device to be connected to multiple other subscriber devices even though the switch has only one port.

[0115] Furthermore, in the optical communication device 1c in the second embodiment, when the signal multiplexing / demultiplexing unit 30c is configured with a plurality of couplers, the signal is distributed to all ports, making it possible to perform multicast communication. When the signal is distributed to all ports in this manner, it is possible that there may be subscriber devices that do not require the signal. In such a case, for the subscriber devices that do not require the signal, it is possible to deal with the problem by, for example, setting the connection destination appropriately in the subordinate switch or setting the wavelength tunable filter so as not to pass unnecessary wavelengths.

[0116] In addition, in the optical communication device 1c in the second embodiment, as in the configuration of the optical communication device 1b in the second variant of the first embodiment shown in Figure 5, only one port may be added to each of switch #A and switch #B (compared to the conventional technology), and the added ports may be further connected to other switches (switch #A' and switch #B' in Figure 5), respectively.

[0117] In addition, in these other switches (switch #A' and switch #B'), a coupler connected to the wavelength management control unit 70c, a coupler connected to the electrical processing unit 80c, or a coupler connected to the return destination (from switch #A' to switch #B', or from switch #B' to switch #A') may be selected. In this case, since signals are multiplexed between the subscriber device and the electrical processing unit 80c, the wavelength management control unit 70c may assign different wavelengths under the same signal multiplexing / demultiplexing unit 30c so that the wavelengths do not conflict with each other.

[0118] [Operation of optical communication device] The operation of the optical communication device 1c in the second embodiment will be described below. As an example, the operation of the optical communication device 1c in upstream communication will be described below. Fig. 8 is a flowchart showing the operation of the optical communication device 1c in the second embodiment of the present invention.

[0119] First, the tunable filter unit 10 receives a signal transmitted from, for example, the subscriber device A shown in Fig. 1 (step S201). The tunable filter unit 10 outputs the received signal to the switch unit 20c at a predetermined wavelength.

[0120] Next, the switch unit 20c accepts the input of the signal output from the wavelength-variable filter unit 10. Each switch of the switch unit 20 transfers the input signal to a desired path. If the input signal is to be transferred to a subscriber device B in the same base, for example, as shown in FIG. 6 (step S202: YES), the switch unit 20 switches the port of switch #A shown in FIG. 7 to (4) (step S203). As a result, the signal is output to switch #B shown in FIG. 7 via the signal multiplexing / demultiplexing unit 30c.

[0121] Switch #B of switch unit 20c receives the signal output from switch #A. Switch #B transmits the input signal to subscriber device B located at the same site (step S204). This completes the operation of optical communication device 1 shown in the flowchart of FIG. 8.

[0122] On the other hand, if the input signal is a signal to be transferred to a subscriber device C (not shown) located at a different site (step S202: NO) and the distance between the subscriber device A and the subscriber device C (not shown) is equal to or greater than a predetermined distance (i.e., a distance that requires electrical processing for regenerative relay) (step S203: YES), the switch unit 20c switches the port of switch #A shown in Fig. 7 to (3) (step S206).

[0123] In this case, the signal is output to the electrical processing unit 80c via the signal demultiplexing unit 30c. The electrical processing unit 80c performs electrical processing on the input signal for regenerative relay (step S207). The signal that has been electrically processed is output to the signal demultiplexing unit 30c via switch #1 of the switch unit 20c shown in FIG.

[0124] On the other hand, if the input signal is a signal to be transferred to a subscriber device C (not shown) located at a different site (step S202: NO) and the distance between the subscriber device A and the subscriber device C (not shown) is shorter than a predetermined distance (i.e., a distance that does not require electrical processing for regeneration and relay) (step S203: NO), the switch unit 20c switches the port of switch #A shown in Fig. 7 to (1) (step S208). As a result, the signal is output to the signal multiplexing / demultiplexing unit 30c.

[0125] Next, the signal demultiplexer 30c receives the signal output from the switch unit 20c. The signal demultiplexer 30c multiplexes the input signal with another signal output from the switch unit 20c (step S209). The signal demultiplexer 30c outputs the multiplexed signal to the internal amplifier unit 40.

[0126] Next, the internal amplifier unit 40 receives the signal output from the signal multiplexing / demultiplexing unit 30c. The internal amplifier unit 40 amplifies the signal power to compensate for loss caused by the signal multiplexing / demultiplexing unit 30c (step S210). The internal amplifier unit 40 outputs the amplified signal to the wavelength multiplexing / demultiplexing unit 50.

[0127] Next, the wavelength multiplexing / demultiplexing unit 50 receives an input of a signal output from the internal amplifier unit 40. The wavelength multiplexing / demultiplexing unit 50 multiplexes the input signal with another signal output from the internal amplifier unit 40 (step S211). The wavelength multiplexing / demultiplexing unit 50 outputs the multiplexed signal to the amplifier unit 60.

[0128] Next, the amplifier unit 60 receives the input of the signal output from the wavelength multiplexing / demultiplexing unit 50. The amplifier unit 60 amplifies the input signal. The amplifier unit 60 outputs the amplified signal to a subscriber device at another point (e.g., subscriber device C, not shown) via the transmission path (step S212). This ends the operation of the optical communication device 1c shown in the flowchart of FIG. 8.

[0129] As described above, the optical communication device 1c in the second embodiment of the present invention can perform return communication. The optical communication device 1c in the second embodiment uses, for example, a device configuration of ROADM, and can perform communication that does not require electrical processing by a transponder.

[0130] Specifically, the optical communication device 1c in the second embodiment switches the ports of each switch in the switch unit 20c to ports that enable return communication when communication is between subscriber devices in the same ROADM (within the own base). Also, the optical communication device 1c in the second embodiment switches the ports of each switch in the switch unit 20c based on the necessity of regeneration and repeating when communication is between a subscriber device in the own base and a subscriber device in another base.

[0131] Furthermore, unlike the optical communication device 1c in the second embodiment described above, the optical communication device 1c in the second embodiment of the present invention realizes return communication between subscriber devices within its own base, and communication between subscriber devices within its own base and subscriber devices at other bases, by using not only the switch unit 20c but also the signal multiplexing / demultiplexing unit 30c.

[0132] With such a configuration, the optical communication device 1c according to the second embodiment of the present invention can suppress increases in device costs and communication delays in both communications within the same location and communications between different locations.

[0133] Furthermore, the optical communication device 1c in the second embodiment is configured to perform electrical processing (for example, processing for regenerative relay by a transponder) by the electrical processing unit 80c when necessary, rather than being required for communication within the same base and communication between different bases. With this configuration, the optical communication device 1c in the second embodiment can omit the performance of electrical processing when not necessary, thereby suppressing an increase in communication delay.

[0134] <Third embodiment> An optical communication device 1d according to the third embodiment of the present invention will now be described.

[0135] [Configuration of optical communication device] FIG. 9 is a diagram showing the overall configuration of an optical communication device 1d according to the third embodiment of the present invention.

[0136] The optical communication device 1d in the third embodiment of the present invention is a device that utilizes a ROADM having a configuration different from that of the optical communication device 1 in the first embodiment and the optical communication device 1c in the second embodiment. As shown in Fig. 9, the optical communication device 1d in the third embodiment includes an amplifier section 60, a wavelength multiplexing / demultiplexing section 50d, an internal amplifier section 40d, a signal multiplexing / demultiplexing section 30d, a switch section 20d, a wavelength tunable filter section 10, a wavelength management control section 70d, and an electrical processing section 80d.

[0137] The configuration of each functional unit of the optical communication device 1d of the third embodiment in upstream communication is as follows.

[0138] The tunable filter unit 10 receives a signal transmitted from a subscriber device and outputs the received signal at a predetermined wavelength to the signal multiplexing / demultiplexing unit 30d.

[0139] The signal multiplexing / demultiplexing unit 30 includes a plurality of couplers. The plurality of couplers of the signal multiplexing / demultiplexing unit 30d receive input of signals output from the plurality of tunable filters of the tunable filter unit 10. The plurality of couplers of the signal multiplexing / demultiplexing unit 30d multiplex the signals input from the plurality of tunable filter units 10. The signal multiplexing / demultiplexing unit 30d outputs the multiplexed signal to the internal amplifier unit 40d.

[0140] The internal amplifier 40d receives the signal output from the signal multiplexing / demultiplexing unit 30d. The internal amplifier 40d amplifies the signal power to compensate for loss caused by multiplexing of the signal by the signal multiplexing / demultiplexing unit 30d. The internal amplifier 40d outputs the amplified signal to the switch unit 20d.

[0141] The switch section 20d receives the input of the signal output from the internal amplifier section 40d. The switch section 20 includes at least one switch. The switch has N×M inputs and outputs (N and M are any natural numbers).

[0142] Each switch in the switch unit 20d transfers the input signal to a desired path, which may be a desired path in the wavelength multiplexing / demultiplexing unit 50d, a path to the wavelength management control unit 70d, a path to the electrical processing unit 80d, or a path to another switch that is a path to a subscriber device that is the destination of the return communication.

[0143] The wavelength multiplexing / demultiplexing unit 50d receives the input of signals output from the multiple switches of the switch unit 20d. The wavelength multiplexing / demultiplexing unit 50d multiplexes the input signals. The wavelength multiplexing / demultiplexing unit 50d outputs the multiplexed signal to the amplifier unit 60.

[0144] The amplifier unit 60 receives the signal output from the wavelength multiplexing / demultiplexing unit 50d, amplifies the input signal, and outputs the amplified signal to the transmission line.

[0145] The configuration of each functional unit of the optical communication device 1 of the first embodiment in downstream communication is as follows.

[0146] The amplifier unit 60 receives an input of a signal arriving from the transmission line side. The amplifier unit 60 amplifies the input signal. The amplifier unit 60 outputs the amplified signal to the wavelength multiplexing / demultiplexing unit 50d.

[0147] The wavelength multiplexing / demultiplexing unit 50d receives the input of the signal output from the amplifier unit 60. The wavelength multiplexing / demultiplexing unit 50d demultiplexes the input signal. The wavelength multiplexing / demultiplexing unit 50d outputs the demultiplexed signals to all the switches of the switch unit 20d.

[0148] Each switch in the switch unit 20d receives an input of a signal output from the wavelength multiplexing / demultiplexing unit 50d. In order to receive a desired signal, each switch in the switch unit 20d switches the port to select the wavelength multiplexing / demultiplexing unit 50d to which the switch is connected. Each switch in the switch unit 20d outputs the input signal directly to the internal amplifier unit 40d, or to the internal amplifier unit 40d via the electrical processing unit 80 and the next switch. Send to.

[0149] The internal amplifier 40d receives the signal output from the wavelength multiplexer / demultiplexer 50d, amplifies the input signal, and outputs the amplified signal to the signal multiplexer / demultiplexer 30d.

[0150] The signal multiplexing / demultiplexing unit 30d receives the signal output from the internal amplifier unit 40d. The signal multiplexing / demultiplexing unit 30d distributes the input signal. The signal multiplexing / demultiplexing unit 30d transmits the distributed signal to the subscriber device via the wavelength-variable filter unit 10.

[0151] In the configuration of the optical communication device 1d in the third embodiment, the configuration of each functional unit other than the switch unit 20d is basically the same as the configuration of the optical communication device 1 in the first embodiment and the optical communication device 1c in the second embodiment. In addition, the optical communication device 1d in the third embodiment is provided with a signal multiplexing / demultiplexing unit 30d and an internal amplifier unit 40d for the purpose of increasing the number of subscriber devices that can be accommodated. However, in the configuration of the optical communication device 1d in the third embodiment, the signal multiplexing / demultiplexing unit 30d and the internal amplifier unit 40d are not essential, and for example, the configuration may be such that signals from the subscriber devices reach the switch unit 20d directly.

[0152] In the optical communication device 1d in the third embodiment, unlike the optical communication device 1 in the first embodiment and the optical communication device 1c in the second embodiment, the switch unit 20d is configured by a WSS having an input / output configuration of N×M (N and M are any natural numbers). However, it is difficult to realize a WSS having an input / output configuration of N×M with a large number of ports. Therefore, as shown in FIG. 10, a WSS having a pseudo input / output configuration of N×M is generally configured by using a WSS having an input / output configuration of 1×N and a WSS having an input / output configuration of 1×M.

[0153] In the case of a WSS with an NxM input / output configuration, three functions called ROADM CDC (Colorless, Directionless, Contentionless) are realized. However, when a pseudo WSS with an NxM input / output configuration is constructed using a WSS with a 1xN input / output configuration and a WSS with a 1xM input / output configuration, the Contentionless function is not realized, and only the Colorless and Directionless functions are realized.

[0154] Hereinafter, the flow of signals will be described with reference to Fig. 10. Fig. 10 is a diagram for explaining details of the switching process by a switch unit 20d of an optical communication device 1d in the third embodiment of the present invention.

[0155] In order for subscriber device A to communicate with subscriber device B that exists at the same site, the port of switch #A, which is a WSS having an N×M configuration and an input / output on the wavelength multiplexing / demultiplexing unit 50d side, is switched to (4).

[0156] On the other hand, when subscriber device A is connected to subscriber device C (not shown) located at a different site, the port of switch #A is switched to (1) or (3). Specifically, for example, when the distance between subscriber device A and subscriber device C (not shown) is short and regenerative relay is not required, the port of switch #A is switched to (1). Conversely, for example, when the distance between subscriber device A and subscriber device C (not shown) is long and regenerative relay is required, the port of switch #A is switched to (3), and the signal is subjected to electrical processing for regenerative relay and then transferred from switch #A to a path toward subscriber device C (not shown).

[0157] In the optical communication device 1 of the first embodiment shown in FIG. 2, and the optical communication device 1c of the second embodiment shown in FIG. 5, switches having an input / output configuration of 1×M are used. Therefore, when connected to port (3) in each switch, it was necessary to further connect to another switch (switch #1 in FIGS. 2 and 5).

[0158] In contrast, as shown in Fig. 10, the switch of the optical communication device 1d in the third embodiment has multiple (N) ports on the subscriber device side, so that the signal that has been electrically processed by the electrical processing unit 80d can be accommodated again by the same switch #A. As a result, the optical communication device 1d in the third embodiment does not need to have a separate switch for electrical processing. This can suppress an increase in device costs. However, in this case, since there is no contentionless function, it is necessary to change the wavelength when the signal is transmitted from the subscriber device to the electrical processing unit 80d and the wavelength when the signal is transmitted from the electrical processing unit 80d to the wavelength multiplexing / demultiplexing unit 50d.

[0159] In addition, the optical communication device 1d in the third embodiment is configured to perform electrical processing (for example, processing for regenerative relay by a transponder) by the electrical processing unit 80d when necessary, rather than being required for communication within the same base and communication between different bases. With this configuration, the optical communication device 1d in the third embodiment can omit the performance of electrical processing when not necessary, thereby suppressing an increase in communication delay.

[0160] In addition, in the optical communication device 1d in the third embodiment, as in the configuration of the optical communication device 1b in the second variant of the first embodiment described above and shown in Figure 5, only one port may be added to each of switch #A and switch #B (compared to the conventional technology), and the added ports may be further connected to other switches (switch #A' and switch #B' in Figure 5), respectively.

[0161] Furthermore, these other switches (switch #A' and switch #B') may be configured to select a coupler connected to the wavelength management control unit 70d, a coupler connected to the electrical processing unit 80d, or a coupler connected to the return destination (from switch #A' to switch #B', or from switch #B' to switch #A').

[0162] [Operation of optical communication device] The operation of the optical communication device 1d in the third embodiment will be described below. As an example, the operation of the optical communication device 1d in upstream communication will be described below. Fig. 11 is a flowchart showing the operation of the optical communication device 1d in the third embodiment of the present invention.

[0163] First, the tunable filter unit 10 receives a signal transmitted from, for example, the subscriber device A shown in Fig. 1 (step S301). The tunable filter unit 10 outputs the received signal at a predetermined wavelength to the signal multiplexing / demultiplexing unit 30d.

[0164] Next, the signal demultiplexing unit 30d receives the input of the signal output from the tunable filter unit 10. The signal demultiplexing unit 30d multiplexes the input signal with another signal output from the tunable filter unit 10 (step S302). The signal demultiplexing unit 30d outputs the multiplexed signal to the internal amplifier unit 40d.

[0165] Next, the internal amplifier 40d receives the signal output from the signal demultiplexer 30d. The internal amplifier 40d amplifies the signal power to compensate for loss caused by the signal multiplexing by the signal demultiplexer 30d (step S303). The internal amplifier 40d outputs the amplified signal to the switch 20d.

[0166] Next, switch unit 20d accepts the input of the signal output from internal amplifier unit 40d. Each switch of switch unit 20d transfers the input signal to a desired path. If the input signal is to be transferred to a subscriber device B in the same base, for example, as shown in FIG. 9 (step S304: YES), switch unit 20d switches the port of switch #A in FIG. 10 to (4) (step S305). As a result, the signal is output to switch #B in FIG. 10.

[0167] Switch #B of switch unit 20d receives the signal output from switch #A. Switch #B transmits the received signal to subscriber device B at the same site (step S306). This completes the operation of optical communication device 1d shown in the flowchart of FIG.

[0168] On the other hand, if the input signal is a signal to be transferred to a subscriber device C (not shown) located at a different site (step S304: NO) and the distance between the subscriber device A and the subscriber device C (not shown) is equal to or greater than a predetermined distance (i.e., a distance that requires electrical processing for regenerative relay) (step S307: YES), the switch unit 20d switches the port of switch #A shown in Fig. 10 to (3) (step S308).

[0169] In this case, the signal is output to the electrical processing unit 80d. The electrical processing unit 80d performs electrical processing on the input signal for regeneration and repeating (step S309). The signal that has been electrically processed is output again to the wavelength multiplexing / demultiplexing unit 50d via switch #A of the switch unit 20d shown in FIG.

[0170] On the other hand, if the input signal is a signal to be transferred to a subscriber device C (not shown) located at a different site (step S304: NO) and the distance between the subscriber devices A and C (not shown) is shorter than a predetermined distance (i.e., a distance that does not require electrical processing for regeneration and relay) (step S307: NO), the switch unit 20d switches the port of switch #A shown in Fig. 10 to (1) (step S310). As a result, the signal is output to the wavelength multiplexing / demultiplexing unit 50d.

[0171] Next, the wavelength multiplexing / demultiplexing unit 50d receives the input of the signal output from the switch unit 20d. The wavelength multiplexing / demultiplexing unit 50d multiplexes the input signal with another signal output from the switch unit 20d (step S311). The wavelength multiplexing / demultiplexing unit 50d outputs the multiplexed signal to the amplifier unit 60.

[0172] Next, the amplifier unit 60 receives the signal output from the wavelength multiplexing / demultiplexing unit 50d. The amplifier unit 60 amplifies the input signal. The amplifier unit 60 outputs the amplified signal to a subscriber device at another point (e.g., subscriber device C, not shown) via the transmission path (step S312). This completes the operation of the optical communication device 1d shown in the flowchart of FIG. 11.

[0173] As described above, the optical communication device 1d in the third embodiment of the present invention can perform return communication. For example, the optical communication device 1d in the third embodiment uses a ROADM device configuration different from that of the first and second embodiments described above, and can perform communication that does not require electrical processing by a transponder.

[0174] Specifically, the optical communication device 1d in the third embodiment switches the ports of each switch in the switch unit 20d to a port that enables return communication when communication is between subscriber devices in the same ROADM (within the own base). Also, the optical communication device 1d in the third embodiment switches the ports of each switch in the switch unit 20d based on the necessity of regeneration and repeating when communication is between a subscriber device in the own base and a subscriber device in another base.

[0175] Also, unlike the optical communication device 1 in the first embodiment and the optical communication device 1c in the second embodiment, the switch unit 20d of the optical communication device 1d in the third embodiment of the present invention is configured with a WSS having an input / output configuration of N x M. As a result, the switch of the optical communication device 1d in the third embodiment has N ports on the subscriber device side, so that the signal that has been electrically processed can be accommodated again by the same switch.

[0176] With such a configuration, the optical communication device 1c according to the third embodiment of the present invention can suppress increases in device costs and communication delays in both communications within the same location and communications between different locations.

[0177] According to the above-described embodiment, the optical communication device includes a connection switching unit and a control unit. For example, the optical communication device is the optical communication device 1, 1a, 1b, or 1d in the embodiment, the connection switching unit is the switch unit 20, 20a, 20b, or 20d in the embodiment, and the control unit is the wavelength management control unit 70 or 70d in the embodiment.

[0178] In the above optical communication device, the connection switching unit connects a first communication port connected to a first communication device belonging to the own base to a second communication port connected to a second communication device belonging to the own base, a third communication port connected to a third communication device belonging to another base, or a fourth communication port connected to an electrical processing unit that performs electrical processing for regeneration and relay on a signal to be transmitted to a fourth communication device belonging to another base.

[0179] For example, the first communication device is subscriber device A in the embodiment, the first communication port is the port on the subscriber device side of switch #A in the embodiment, the second communication device is subscriber device B in the embodiment, the second communication port is port (4) in the embodiment, the third communication device and the fourth communication device are subscriber device C (not shown) located at a different base in the embodiment, the third communication port is port (1) in the embodiment, the electrical processing unit is electrical processing unit 80 and 80d in the embodiment, and the fourth communication port is port (3) in the embodiment.

[0180] In the above communication device, the control unit controls the connection switching of the communication port by the connection switching unit based on the base to which the communication device that communicates with the first communication device belongs and on the necessity of electrical processing.

[0181] The optical communication device may further include a signal demultiplexing unit and an internal amplifier. In this case, for example, the optical communication device is the optical communication device 1, 1b, or 1d in the embodiment, the signal demultiplexing unit is the signal demultiplexing unit 30, 30b, or 30d in the embodiment, and the internal amplifier is the internal amplifier 40 or 40d in the embodiment. In this case, the signal demultiplexing unit multiplexes the signals output from the multiple connection switching units. For example, the multiple connection switching units are the multiple switches included in the switch units 20, 20b, or 20d in the embodiment. In this case, the internal amplifier amplifies the signal multiplexed by the signal demultiplexing unit and compensates for the signal loss due to the multiplexing.

[0182] According to the above-described embodiment, the optical communication device includes a connection switching unit, a signal multiplexing / demultiplexing unit, and a control unit. For example, the optical communication device is the optical communication device 1c in the embodiment, the connection switching unit is the switch unit 20c in the embodiment, the signal multiplexing / demultiplexing unit is the signal multiplexing / demultiplexing unit 30c in the embodiment, and the control unit is the wavelength management control unit 70c in the embodiment.

[0183] In the above optical communication device, the multiple connection switching units connect the first communication port to the second communication port, the third communication port, or the fourth communication port. For example, the multiple connection switching units are multiple switches included in the switch unit 20c in the embodiment, the first communication port is a port on the subscriber device side of the switch #A in the embodiment, the second communication port is the port (4) in the embodiment, the third communication port is the port (1) in the embodiment, and the fourth communication port is the port (3) in the embodiment.

[0184] In the above optical communication device, the signal multiplexing / demultiplexing unit multiplexes the signals output from the multiple connection switching units, connects the first communication port to the first communication device belonging to the own base, connects the second communication port to the second communication device belonging to the own base, connects the third communication port to the third communication device belonging to the other base, and connects the fourth communication port to an electrical processing unit that performs electrical processing for regeneration and relay on the signal transmitted to the fourth communication device belonging to the other base. For example, the first communication device is the subscriber device A in the embodiment, the second communication device is the subscriber device B in the embodiment, the third communication device and the fourth communication device are the subscriber device C (not shown) existing at the different base in the embodiment, the third communication port is the port (1) in the embodiment, and the electrical processing unit is the electrical processing unit 80c in the embodiment.

[0185] In the optical communication device, the control unit controls the connection switching of the communication port by the connection switching unit based on the base to which the communication device that communicates with the first communication device belongs and on the necessity of electrical processing.

[0186] In the above optical communication device, the connection switching unit may have a wavelength selective switch. In this case, for example, the optical communication device is the optical communication device 1, 1a, 1b, or 1c in the embodiment, and the connection switching unit is the switch unit 20, 20a, 20b, or 20c in the embodiment. In this case, the wavelength selective switch connects the first communication port to any one of the second communication port, the third communication port, or the fourth communication port.

[0187] In the above optical communication device, the connection switching unit may have a wavelength selective switch. In this case, for example, the optical communication device is the optical communication device 1d in the embodiment, the connection switching unit is the switch unit 20d in the embodiment, and the wavelength selective switch is switch #A of the switch unit 20d in the embodiment. In this case, the wavelength selective switch selects and connects one of the N communication ports (N is any natural number) to one of the M communication ports (M is any natural number).

[0188] In this case, the first communication port is one of the N communication ports, and the second communication port, the third communication port, and the fourth communication port are each one of the M communication ports. For example, the first communication port is a port on the subscriber device side of switch #A in the switch unit 20d in the embodiment, the second communication port is port (4) in the switch unit 20d in the embodiment, the third communication port is port (1) in the switch unit 20d in the embodiment, and the fourth communication port is port (3) in the switch unit 20d in the embodiment.

[0189] A part of the optical communication devices 1, 1a to 1d in each of the above-mentioned embodiments may be realized by a computer. In that case, a program for realizing the function may be recorded in a computer-readable recording medium, and the program recorded in the recording medium may be read into a computer system and executed to realize the function. The term "computer system" as used herein includes hardware such as an OS and peripheral devices. The term "computer-readable recording medium" refers to a portable medium such as a flexible disk, an optical magnetic disk, a ROM, a CD-ROM, and a storage device such as a hard disk built into a computer system. The term "computer-readable recording medium" may also include a medium that dynamically holds a program for a short period of time, such as a communication line when a program is transmitted via a network such as the Internet or a communication line such as a telephone line, and a medium that holds a program for a certain period of time, such as a volatile memory inside a computer system that is a server or a client in that case. The above-mentioned program may be a program for realizing a part of the above-mentioned function, or may be a program that can realize the above-mentioned function in combination with a program already recorded in the computer system, or may be a program that is realized using a programmable logic device such as an FPGA (Field Programmable Gate Array).

[0190] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and designs that do not deviate from the gist of the present invention are also included. [Explanation of symbols]

[0191] 1, 1a, 1b, 1c, 1d...Optical communication device, 10...Wavelength tunable filter section, 20, 20b, 20c, 20d...Switch section, 30, 30c, 30d...Signal multiplexing / demultiplexing section, 40, 40d...Internal amplifier section, 50, 50d...Wavelength multiplexing / demultiplexing section, 60...Amplifier section, 70, 70b, 70c, 70d...Wavelength management control section, 80, 80b, 80c, 80d...Electrical processing section

Claims

1. a connection switching unit that connects a first communication port connected to a first communication device belonging to the own base to a second communication port connected to a second communication device belonging to the own base, a third communication port connected to a third communication device belonging to another base, or a fourth communication port connected to an electrical processing unit that performs electrical processing for regeneration and relay on a signal to be transmitted to a fourth communication device belonging to the other base; a control unit that controls the connection switching of the communication port by the connection switching unit based on a base to which a communication device that communicates with the first communication device belongs and on the necessity of the electrical processing; An optical communication device comprising:

2. a signal multiplexing / demultiplexing unit that multiplexes the signals output from the plurality of connection switching units; an internal amplifier that amplifies the signal multiplexed by the signal multiplexing / demultiplexing unit and compensates for loss of the signal due to the multiplexing; The optical communication device according to claim 1 , further comprising:

3. a plurality of connection switching units that connect the first communication port to the second communication port, the third communication port, or the fourth communication port; a signal multiplexing / demultiplexing unit that multiplexes the signals output from the plurality of connection switching units, connects the first communication port to a first communication device belonging to the own base, connects the second communication port to a second communication device belonging to the own base, connects the third communication port to a third communication device belonging to another base, and connects the fourth communication port to an electrical processing unit that performs electrical processing such as regeneration and relay on a signal to be transmitted to a fourth communication device belonging to another base; a control unit that controls the connection switching of the communication port by the connection switching unit based on a base to which a communication device that communicates with the first communication device belongs and on the necessity of the electrical processing; An optical communication device comprising:

4. The connection switching unit includes a wavelength selective switch that connects the first communication port to any one of the second communication port, the third communication port, and the fourth communication port.

4. An optical communication device according to claim 1.

5. the connection switching unit has a wavelength selective switch that selects and connects one of N communication ports (N is any natural number) to one of M communication ports (M is any natural number); The first communication port is one of the N communication ports, and the second communication port, the third communication port, and the fourth communication port are each one of the M communication ports.

3. An optical communication device according to claim 1 or 2.

6. a connection switching step of connecting a first communication port connected to a first communication device belonging to the own base to a second communication port connected to a second communication device belonging to the own base, a third communication port connected to a third communication device belonging to another base, or a fourth communication port connected to an electrical processing unit that performs electrical processing for regeneration and relay on a signal to be transmitted to a fourth communication device belonging to the other base; a control step of controlling the connection switching of the communication port in the connection switching step based on a base to which a communication device that communicates with the first communication device belongs and on the necessity of the electrical processing; An optical communication method comprising:

7. a connection switching step in which a plurality of connection switching units connect the first communication port to the second communication port, the third communication port, or the fourth communication port, respectively; a signal multiplexing / demultiplexing step of multiplexing signals output from the plurality of connection switching units, connecting the first communication port to a first communication device belonging to the own base, connecting the second communication port to a second communication device belonging to the own base, connecting the third communication port to a third communication device belonging to another base, and connecting the fourth communication port to an electrical processing unit that performs electrical processing for regenerating and repeating a signal to be transmitted to a fourth communication device belonging to another base; a control step of controlling the connection switching of the communication port in the connection switching step based on a base to which a communication device that communicates with the first communication device belongs and on the necessity of the electrical processing; An optical communication method comprising:

8. In the connection switching step, one of the N communication ports (N is any natural number) and one of the M communication ports (M is any natural number) are selected and connected to each other, The first communication port is one of the N communication ports, and the second communication port, the third communication port, and the fourth communication port are each one of the M communication ports. The optical communication method according to claim 6.

Images