Optical communication device and control method

Abstract

One aspect of the present invention pertains to an optical communications device comprising: a detection unit that detects the rising or falling edge of a control signal output to an optical communication path from a user device; and an optical modulation unit that superimposes a new control signal on the main signal if a rising or falling edge of a control signal is detected by the detection unit.

Description

[Technical field]

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

[0002] User equipment is connected by optical fibers as shown in Fig. 7, and communication using optical signals is carried out between optical transmitters and receivers installed in the user equipment. User equipment A in Fig. 7 is composed of a transmitter 1, a receiver 1, a control signal superimposing unit 1, a control signal extracting unit 1, and a transmitter / receiver separator 1. User equipment B is composed of a transmitter 2, a receiver 2, a control signal superimposing unit 2, a control signal extracting unit 2, and a transmitter / receiver separator 2.

[0003] In user device A, a transmitter 1 outputs a main signal 1, and a control signal superimposing unit 1 superimposes a control signal 1 including status information (wavelength, power, temperature, etc.), and outputs the signal to an optical fiber via a transmitter / receiver separator 1. At this time, the control signal is superimposed as an AMCC (Auxiliary Management and Control Channel) on a low frequency band that does not interfere with the main signal, for example. This allows the signals to be treated as physically separate signals.

[0004] User device B converts the received optical signal into an electrical signal using a photodiode (PD) or the like, then separates it and handles it as individual electrical signals. User device B extracts control signal 1 from the signal received via transmitter / receiver separator 1 at control signal extractor 2, and receives main signal 1 at receiver 2. Communication from user device B to user device A is performed in a similar manner. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] K. Honda et al., “WDM Passive Optical Network Managed with Embedded Pilot Tone for Mobile Fronthaul,” ECOC2015, We.3.4.4, 2015. Summary of the Invention [Problem to be solved by the invention]

[0006] In the conventional technology, it is assumed that control signals are transmitted and received between user devices A and B as shown in Fig. 7. Therefore, there is a problem that it is difficult to superimpose a new control signal on a main signal from a device other than the user device during communication between the user devices.

[0007] In view of the above circumstances, an object of the present invention is to provide a technique that enables a new control signal to be superimposed on a main signal. [Means for solving the problem]

[0008] One aspect of the present invention is an optical communication device comprising a detection unit that detects a rising or falling edge of a control signal output from a user device to an optical communication path, and an optical modulation unit that superimposes a new control signal on a main signal when the detection unit detects a rising or falling edge of the control signal.

[0009] One aspect of the present invention is a control method comprising: a detection step in which a detection unit detects a rising edge or a falling edge of a control signal output from a user device to an optical communication path; and a superimposition step in which an optical modulation unit superimposes a new control signal onto a main signal when a rising edge or a falling edge of the control signal is detected by the detection step. Effect of the Invention

[0010] The present invention makes it possible to superimpose a new control signal on a main signal. [Brief description of the drawings]

[0011] [Figure 1] 1 is a diagram showing a basic configuration of an optical communication device 10. [Figure 2A] FIG. 2 is a diagram illustrating an example of transmission of a main signal and a control signal. [Figure 2B] FIG. 13 is a diagram for explaining superimposition of a control signal. [Diagram 3] 2 is a diagram showing an example of the configuration of a control signal superimposing unit 200. FIG. [Figure 4] FIG. 2 is a diagram illustrating an example of the configuration of an optical communication device 10-1. [Diagram 5] FIG. 2 is a diagram illustrating an example of the configuration of an optical communication device 10-2. [Figure 6] FIG. 2 is a diagram illustrating an example of the configuration of an optical communication device 10-3. [Figure 7] FIG. 1 is a diagram showing an example of a conventional configuration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Note that the same parts in the various drawings are given the same reference numerals, and the description thereof will be omitted.

[0013] 1 is a diagram showing a basic configuration of an optical communication device 10. The optical communication device 10 is connected to optical transmitters and receivers 300 and 400 via optical fibers (optical communication paths). The optical communication device 10 also includes a management control function unit 100 and a control signal superimposing unit 200.

[0014] The optical transceivers 300 and 400 are examples of user devices. The optical transceivers 300 and 400 can transmit and receive control signals including various setting parameters of the optical transceiver and user information by superimposing the control signals on a main signal, which is a user signal. The optical transceivers 300 and 400 also transmit and receive the control signals as intermittent burst signals at certain intervals.

[0015] The management control function unit 100 in the optical communication device 10 outputs a control signal to be superimposed on a main signal to the control signal superimposing unit 200. The control signal superimposing unit 200 superimposes the control signal output by the management control function unit 100 between intermittent control signals transmitted from the optical transceiver 300.

[0016] Specifically, an example in which a signal is transmitted from the optical transceiver 300 to the optical transceiver 400 will be described. Figures 2A and 2B are diagrams for explaining the superposition of a control signal. Figure 2A is a diagram showing an example of transmission of a main signal and a control signal. In Figure 2A, the horizontal axis indicates time. As shown in Figure 2A, the control signal is transmitted as a burst signal.

[0017] 2B, the control signal superimposing unit 200 superimposes the control signal output by the management control function unit 100 between the intermittent control signals transmitted from the optical transceiver 300. The optical transceiver 400 on the receiving side processes the control signal in the same manner as for a normal control signal. Also, when a signal is transmitted from the optical transceiver 400 to the optical transceiver 300, the control signal is superimposed in the same manner.

[0018] In this way, by making the control signal from the optical transceiver an intermittent burst signal and further subjecting the control signal to time division multiplexing (TDM) within the transmission path, it becomes possible to superimpose (modulate) a new control signal within the transmission path, which was previously difficult.

[0019] The intervals between the intermittent control signals transmitted from the optical transceivers 300 and 400 may be predetermined or may be any interval. When the intervals between the control signals are set to any interval, the maximum frame size of the control signal frame may be specified in advance and the intervals may be set to be equal to or larger than the maximum frame size. For example, the intervals may be determined according to the control signal superimposing unit 200, as described later.

[0020] Next, a configuration example of the control signal superimposing unit 200 will be described. Fig. 3 is a diagram showing a configuration example of the control signal superimposing unit 200. The control signal superimposing unit 200 is composed of a signal timing detector 210 and an optical modulator 220. The signal timing detector 210 and the optical modulator 220 can transmit and receive signals to and from each other. For the transmission and reception of signals, for example, wiring capable of transmitting and receiving electrical signals may be provided between the signal timing detector 210 and the optical modulator 220.

[0021] The signal timing detector 210 detects the rising or falling edge of the control signal output from the optical transceiver 300. The optical modulator 220 is a mechanism that can apply a signal input to the optical modulator as a modulating signal to the input light, and is, for example, an LN (LiNbO3: lithium niobate) modulator, an EA (electro-absorption) modulator, or an SOA (semiconductor optical amplifier). A new control signal is input from the management control function unit 100 to the optical modulator 220, which superimposes the input new control signal. The new control signal to be superimposed is also referred to as a "new control signal."

[0022] When the signal timing detector 210 detects the falling edge of the control signal output from the optical transceiver 300, the detection of the falling edge is notified to the optical modulator 220 by feedforward control. When notified of the detection of the falling edge, the optical modulator 220 determines that this is the start time of a no-signal section and superimposes a new control signal.

[0023] At this time, the time from when the signal timing detector 210 detects a falling edge until the optical modulator 220 actually superimposes the new control signal is set as the response time τ of the control signal superimposing section 200 .

[0024] As described above, the interval of the intermittent control signals output from the optical transceivers 300, 400 is set so that the control signals output from the optical transceivers 300, 400 do not collide with the new control signals. Specifically, the response time τ, which is the time from when the signal timing detector 210 detects the falling edge of the control signal to when the optical modulator 220 superimposes a new control signal, is set to be equal to or less than the time obtained by subtracting the transmission time of the control signal from the interval at which the optical transceivers 300, 400 transmit the control signal, divided by 2. Note that the transmission time here is the transmission time of the control signal with the largest size among the control signals.

[0025] Conversely, if the interval for transmitting the control signal of the optical transceiver 300 can be set, collision of new control signals can be prevented by setting the interval to be longer than the transmission time of the control signal plus twice the above-mentioned τ.

[0026] In the above embodiment, the signal timing detector 210 detects the falling edge of the control signal output from the optical transceiver 300, but a case where the signal timing detector 210 detects the rising edge will be described. For example, the frame size of the control signal frame is predefined, and the interval between the control signals is set to an interval equal to or longer than the time required for transmitting the frame size (defined as "T1"). In this case, the signal timing detector 210 detects the rising edge, and the timing T1 elapsed from that timing (defined as "timing T2") becomes the falling edge timing. Then, the control signal is not transmitted until at least the time T1 has elapsed from the timing T2. Therefore, the optical modulator 220 determines the timing T2 as the detection timing of the falling edge, and superimposes the new control signal in the same manner as in the case where the falling edge is detected. In this way, even if the signal timing detector 210 detects the rising edge, the new control signal can be superimposed.

[0027] (Variation 1) 4 is a diagram showing an example of the configuration of an optical communication device 10-1 which is a first modified example of the optical communication device 10. The optical communication device 10-1 in the first modified example includes transmitter / receiver separation devices 500 and 600. The optical communication device 10-1 also includes two control signal superimposing units 200-1 and 200-2. Each of the control signal superimposing units 200-1 and 200-2 includes a signal timing detector and an optical modulator as described in FIG. 3. The management control function unit 100 outputs a new control signal to each of the control signal superimposing units 200-1 and 200-2.

[0028] The new control signal superimposed by the control signal superimposing units 200-1, 200-2 uses as a pilot tone a frequency that is the same as the control signal transmitted by the optical transceivers 300, 400, or a frequency in a lower frequency range than the main signal. Note that a high frequency may be used as long as the optical transceivers 300, 400 can separate the main signal from the control signal. Note that the pilot tone may be a signal up-converted to a high frequency (e.g., 500 kHz) that does not affect the main signal, or a signal modulated at baseband.

[0029] The optical transceiver 300 and the transmitter / receiver separator 500 are connected by an optical fiber. The transmitter / receiver separator 500 and the control signal superimposing unit 200-1 are connected by an optical fiber. The transmitter / receiver separator 500 and the control signal superimposing unit 200-2 are connected by an optical fiber. The transmitter / receiver separator 600 and the control signal superimposing unit 200-1 are connected by an optical fiber. The transmitter / receiver separator 600 and the control signal superimposing unit 200-2 are connected by an optical fiber. The optical transceiver 400 and the transmitter / receiver separator 600 are connected by an optical fiber.

[0030] The signal transmitted from the optical transceiver 300 is input to the control signal superimposing unit 200-1 via the transmission / reception separator 500, where a new control signal is superimposed thereon, and the signal is transmitted to the optical transceiver 400 via the transmission / reception separator 600. Conversely, the signal transmitted from the optical transceiver 400 is input to the control signal superimposing unit 200-2 via the transmission / reception separator 600, where a new control signal is superimposed thereon, and the signal is transmitted to the optical transceiver 300 via the transmission / reception separator 500. Unlike the conventional technique, the control signal superimposing units 200-1 and 200-2 enable the transmission of a control signal for setting a wavelength from the management control function unit 100 even after the connection of the optical transceivers 300 and 400 has been completed.

[0031] In this way, when the optical signal output to the optical communication path includes up and down signals, the optical modulation unit is provided with two optical modulation units: an upstream signal optical modulation unit (optical modulator provided in control signal superimposition unit 200-1) that superimposes a new control signal on the upstream signal, and a downstream signal optical modulation unit (optical modulator provided in control signal superimposition unit 200-2) that superimposes a new control signal on the downstream signal.

[0032] (Variation 2) 5 is a diagram showing a configuration example of an optical communication device 10-2 which is a second modification of the optical communication device 10. The optical communication device 10-2 in the second modification includes a switch 900-1 and an optical SW control function unit 700. The switch 900-1 connects the subscriber devices 800-1, 800-2, and 800-3 to the management control function unit 100 and the control signal superimposing unit 200. The optical SW control function unit 700 controls the switch 900-1. The control signal superimposing unit 200 connects to the switch 900-2. The switch 900-2 connects to the subscriber device 800-4.

[0033] The switch 900-1 and the control signal superimposing unit 200 are collectively referred to as GW1000-1. The switch 900-2 and the customer equipment 800-4 are collectively referred to as GW1000-2. The customer equipments 800-1, 800-2, 800-3, and 800-4 include the functions included in the optical transceivers 300 and 400 described above. The management control function unit 100 is an example of a setting unit. The switch 900-1 is an example of a connection destination changing unit.

[0034] The subscriber devices 800-1, 800-2, and 800-3 are each connected to the optical communication device 10-2 via an optical fiber. The optical communication device 10-2 and the GW 1000-2 are connected to each other via an optical fiber.

[0035] The operation when a new subscriber device 800-1 is connected to the configuration shown in Fig. 5 will be described. The subscriber device 800-1 is first connected to the management control function unit 100 by the switch 900-1. The management control function unit 100 sets a wavelength for the subscriber device 800-1 according to the communication destination (service, user, etc.).

[0036] Thereafter, the switch 900-1 switches the path under the control of the optical SW control function unit 700 (S1). As a result, the subscriber device 800-1 starts communication with the desired connection destination (the subscriber device 800-4 in the case of FIG. 5) via the control signal superimposing unit 200.

[0037] When subscriber device 800-1 and subscriber device 800-4 are communicating with each other and subscriber device 800-1 connects to another subscriber device other than subscriber device 800-4 (for example, when a switching request is sent from subscriber device 800-1), it is necessary to set the wavelength to be used in communication with the other subscriber device.

[0038] Here, a configuration example for receiving a switching request will be described. A branching unit for branching a control signal exchanged between subscriber devices is provided between the switch 900-1 and the control signal superimposing unit 200. Also, a control TRx for receiving a signal branched from the branching unit is provided in the optical communication device 10-2. In this configuration, for example, when the subscriber device 800-1 switches the communication destination, the subscriber device 800-1 transmits a disconnection request to the subscriber device 800-4. The disconnection request is a signal indicating that the communication connection will be subsequently disconnected.

[0039] The control TRx transmits an ACK to the subscriber device 800-1 in response to the disconnection request received by demodulating the control signal branched from the branching unit. The subscriber device 800-1 stops emitting light to the communication path in response to the transmission of the disconnection request. The optical SW control function unit 700 recognizes the stop of light emission.

[0040] When a predetermined time has elapsed since the subscriber device 800-1 stopped emitting light, the subscriber device 800-1 resumes emitting light to the communication path. When the optical SW control function unit 700 detects light at an input / output port to which no light has been input for a predetermined time, the optical SW control function unit 700 connects the input / output port from which the light has been detected to the management control function unit 100. The subscriber device 800-1 transmits a connection switching request to the management control function unit 100.

[0041] The connection switching request includes information indicating the new destination subscriber device. When the management control function unit 100 receives the connection switching request, it transmits an ACK to the source subscriber device 800-1. The management control function unit 100 determines the wavelength to be used in communication between the subscriber device 800-1 and the newly connected subscriber device.

[0042] When the wavelength to be used for communication with the newly connected subscriber device is determined by the above process, the management control function unit 100 outputs a new control signal for setting the wavelength to be used to the control signal superimposing unit 200, and the control signal superimposing unit 200 superimposes the signal to be superimposed. In the above description, a configuration using a "control TRx" was described as an example of receiving a signal from the subscriber device 800-1, but since a Tx is not necessary, a "control Rx" may be used instead of the "control TRx". Furthermore, the "control Rx" does not have to be a main signal receiver (for example, a 10G (bit / s) class receiver) as long as it can receive a low-speed signal using an AMCC (Auxiliary Management and Control Channel).

[0043] The subscriber device 800-1 receives the superimposed new control signal and sets the wavelength to be used in communication with other subscriber devices. After that, the switch 900-1 switches the path under the control of the optical SW control function unit 700 (S2).

[0044] The control signal superimposing unit 200 allows the management control function unit 100 to transmit a control signal for managing wavelengths even after the subscriber device has completed communication with the desired connection destination. Although the case where a switch request is transmitted from the subscriber device 800-1 has been taken as an example of a case where a connection is made to another subscriber device, the present invention is not limited to this. For example, the management control function unit 100 may switch the connection destination due to a failure in the optical communication path or various related devices. Also, a control signal superimposing unit may be provided between the subscriber device 800-1 and the connection destination switched by S2.

[0045] (Variation 3) Instead of the configuration shown in Fig. 5, a control signal superimposing unit 200 may be provided between the subscriber device and the switch. This will be specifically described with reference to Fig. 6. Fig. 6 is a diagram showing an example of the configuration of an optical communication device 10-3 which is a third modification of the optical communication device 10. The optical communication device 10-3 in the third modification includes a switch 900-1 and an optical SW control function unit 700. Furthermore, a control signal superimposing unit is provided for each subscriber device. In the case of Fig. 5, the subscriber devices 800-1, 800-2, and 800-3 are provided with the control signal superimposing units 200-1, 200-2, and 200-3, respectively.

[0046] The subscriber device 800-1 is provided between the subscriber device 800-1 and the switch 900-3. The subscriber device 800-2 is provided between the subscriber device 800-2 and the switch 900-3. The subscriber device 800-3 is provided between the subscriber device 800-3 and the switch 900-3. The subscriber devices 800-1, 800-2, and 800-3 are each connected to the optical communication device 10-2 by an optical fiber.

[0047] The control signal superimposing unit 200 is connected to the control signal superimposing units 200-1, 200-2, and 200-3. The control signal superimposing unit 200 outputs a new control signal to each of the control signal superimposing units 200-1, 200-2, and 200-3.

[0048] The operation when a new subscriber device 800-1 is connected to the configuration shown in Fig. 6 will be described. The subscriber device 800-1 is first connected to the management control function unit 100 by the switch 900-3. The management control function unit 100 sets a wavelength for the subscriber device 800-1 according to the communication destination (service, user, etc.).

[0049] Thereafter, the switch 900-3 switches the path under the control of the optical SW control function unit 700. As a result, the subscriber device 800-1 starts communication with the desired connection destination. When the subscriber device 800-1 connects to another subscriber device different from the desired connection destination while the subscriber device 800-1 is communicating with the desired connection destination, the management control function unit 100 outputs a new control signal to the control signal superimposing unit 200, and the control signal superimposing unit 200 superimposes the signal to be superimposed, as in the second modification.

[0050] In the configuration shown in the modified example 3, a control signal superimposing unit is provided for each subscriber device, so that the load of management and control by the management control function unit 100 is reduced compared to the configuration shown in the modified example 2.

[0051] The management control function unit 100, the control signal superimposing units 200, 200-1, 200-2, and the optical SW control function unit 700 may be configured using a processor such as a CPU (Central Processing Unit) and a memory. In this case, the management control function unit 100, the control signal superimposing units 200, 200-1, 200-2, and the optical SW control function unit 700 function as the management control function unit 100, the control signal superimposing units 200, 200-1, 200-2, and the optical SW control function unit 700 by the processors executing programs in the respective units. Note that all or part of the functions of the management control function unit 100, the control signal superimposing units 200, 200-1, 200-2, and the optical SW control function unit 700 may be realized using hardware such as an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array). The above programs may be recorded in a computer-readable recording medium. The computer-readable recording medium is, for example, a portable medium such as a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, or a semiconductor storage device (e.g., an SSD: Solid State Drive), or a storage device such as a hard disk or a semiconductor storage device built into a computer system. The above program may be transmitted via a telecommunication line.

[0052] 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. [Industrial Applicability]

[0053] The present invention is applicable to optical communication devices that perform communication via optical fibers. [Explanation of symbols]

[0054] 10, 10-1, 10-2, 10-3...Optical communication device 100...Management and control function unit 200, 200-1, 200-2, 200-3...Control signal superimposing unit 210...signal timing detector 220...Optical modulator 300, 400...Optical transmitter / receiver 500, 600...Transmitter / receiver separator 700…Control function section 800-1, 800-2, 800-3, 800-4…Subscriber equipment 900-1, 900-2, 900-3… Switch

Claims

1. a detection unit that detects a rising or falling edge of a control signal output from a user device to an optical communication path; an optical modulation unit that superimposes a new control signal on a main signal when the detection unit detects a rising or falling edge of the control signal; An optical communication device comprising:

2. The optical communication device according to claim 1, wherein the time from when the falling edge of a control signal is detected by the detection unit to when a new control signal is superimposed by the optical modulation unit is equal to or less than the time obtained by subtracting the transmission time of the control signal from the interval at which the user equipment transmits the control signal, divided by 2.

3. 3. The optical communication device according to claim 1 or 2, wherein when the optical signal output to the optical communication path includes an uplink signal, the optical modulation unit comprises two optical modulation units: an upstream signal optical modulation unit that superimposes a new control signal on the upstream signal, and a downstream signal optical modulation unit that superimposes a new control signal on the downstream signal.

4. A setting unit that sets a wavelength used by a user device for communication; a connection destination change unit that changes a connection destination of a user device; Equipped with the connection destination changing unit, when the user device starts communication with a desired connection destination, connects the user device to the setting unit, and then connects the user device to the desired connection destination via the optical modulation unit; 2. The optical communication device according to claim 1, wherein when the user equipment switches from the desired connection destination to another connection destination and starts communication, the optical modulation unit superimposes a control signal for setting the wavelength set by the setting unit.

5. A setting unit that sets a wavelength used by a user device for communication; a connection destination change unit that changes a connection destination of a user device; Equipped with the user device is connected to the connection destination changing unit via the optical modulation unit provided for each user device; the connection destination change unit, when the user device starts communication with a desired connection destination, connects the user device to the setting unit, and then connects the user device to the desired connection destination; 2. The optical communication device according to claim 1, wherein when the user equipment switches from the desired connection destination to another connection destination and starts communication, the optical modulation unit superimposes a control signal for setting the wavelength set by the setting unit.

6. a detection step in which a detection unit detects a falling edge or a rising edge of a control signal output from a user device to an optical communication path; a superimposing step of superimposing a new control signal on the main signal by the optical modulation unit when a falling edge or a rising edge of the control signal is detected by the detecting step; A control method comprising:

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