Optical remote control system, optical transceiver, remote control device, optical wavelength multiplex coupler, and optical remote control method

Abstract

An optical remote control system according to the present invention comprises: a plurality of optical transceivers connected to an optical communication network for transmitting an optical signal in which a plurality of main signals are wavelength-division multiplexed; and a remote control device connected to the optical communication network. The remote control device includes a control-purpose optical transmission / reception unit for transmitting a control signal of a single wavelength. Each of the plurality of optical transceivers includes: a first optical transmission / reception unit for transmitting / receiving the main signal; a second optical transmission / reception unit for receiving the control signal separated from an optical multiplex signal in which the main signal and the control signal are wavelength-division multiplexed; and a control unit for controlling the first optical transmission / reception unit on the basis of the control signal received by the second optical transmission / reception unit. The second optical transmission / reception unit transmits a response signal of a single wavelength to the control signal as a burst optical signal.

Description

Optical remote control system, optical transceiver, remote control device, optical wavelength division multiplexing coupler, and optical remote control method

[0001] This disclosure relates to an optical remote control system, an optical transceiver, a remote control device, an optical wavelength division multiplexing coupler, and an optical remote control method. This application claims priority to Japanese Application No. 2024-067614 filed on April 18, 2024, and incorporates the entire content of said Japanese application by reference.

[0002] Patent Document 1 discloses a technique for allocating wavelengths of wavelength-tunable optical transceivers in ONUs (Optical Network Units) of PONs (Passive Optical Networks) using control signals such as AMCC (Auxiliary Management and Control Channel) and OAM (Operations, Administration, and Maintenance).

[0003] In recent years, an all-photonics network (APN) has been developed that performs end-to-end optical communication within a network. In an APN, a wavelength is assigned to each user device or application, and communication paths are controlled by the wavelength.

[0004] International Publication No. 2020 / 091396

[0005] An optical remote control system according to one aspect of the present disclosure comprises a plurality of optical transceivers connected to an optical communication network that transmits an optical signal in which a plurality of main signals are wavelength-division multiplexed, and a remote control device connected to the optical communication network, wherein the remote control device includes a control optical transceiver that transmits a plurality of control signals of a single wavelength, and each of the plurality of optical transceivers includes a first optical transceiver that transmits and receives the main signals, a second optical transceiver that receives the control signals separated from an optical multiplexed signal in which the main signals and the control signals are wavelength-division multiplexed, and a control unit that controls the first optical transceiver based on the control signals received by the second optical transceiver, and the second optical transceiver transmits a single-wavelength response signal to the control signal as a burst optical signal.

[0006] FIG. 1 is a diagram illustrating an example of the configuration of an optical communication system according to an embodiment. FIG. 2A is a diagram illustrating a first example of the configuration of an optical remote control system according to an embodiment. FIG. 2B is a diagram illustrating a second example of the configuration of an optical remote control system according to an embodiment. FIG. 3 is a diagram illustrating an example of the hardware configuration of an optical transceiver. FIG. 4 is a diagram illustrating an example of a frame format of an extended OAM frame. FIG. 5 is a sequence diagram illustrating an example of remote control of an optical transceiver in an optical remote system according to an embodiment. FIG. 6 is a schematic diagram illustrating an example of downstream communication in an optical remote control system according to an embodiment. FIG. 7 is a schematic diagram illustrating an example of upstream communication in an optical remote control system according to an embodiment. FIG. 8 is a diagram illustrating a first modified example of an optical remote control system according to an embodiment. FIG. 9 is a diagram illustrating a second modified example of an optical remote control system according to an embodiment. FIG. 10 is a diagram illustrating a third modified example of an optical remote control system according to an embodiment. FIG. 11 is a diagram illustrating a fourth modified example of an optical remote control system according to an embodiment. FIG. 12 is a block diagram illustrating the circuit configuration of a frame processing unit in a fifth modified example of an optical transceiver according to an embodiment. FIG. 13 is a flowchart illustrating the operation of a processor in the fifth modified example of an optical transceiver according to an embodiment.

[0007] <Problem to be Solved by the Present Disclosure> In an APN, optical transceivers installed in user devices must be remotely controlled from the central office of the telecommunications carrier that owns and manages the APN. At the same time, it is desirable to reduce the number of wavelengths used for control signals in order to ensure the number of wavelengths used for main signals. Furthermore, given the stringent requirements for power consumption, implementing remote control on optical transceivers also necessitates reducing the power consumption of the optical transceivers.

[0008] <Effects of the Present Disclosure> According to the present disclosure, it is possible to reduce the number of wavelengths used to control an optical transceiver, and also to reduce the power consumption of the optical transceiver.

[0009] <Outline of Embodiments of the Present Disclosure> Below, an outline of embodiments of the present disclosure will be listed and described.

[0010] (1) An optical remote control system according to this embodiment includes a plurality of optical transceivers connected to an optical communication network that transmits an optical signal obtained by wavelength-division multiplexing a plurality of main signals, and a remote control device connected to the optical communication network, wherein the remote control device includes a control optical transceiver that transmits a plurality of control signals having a single wavelength, and each of the plurality of optical transceivers includes a first optical transceiver that transmits and receives the main signals, a second optical transceiver that receives the control signals separated from an optical multiplexed signal obtained by wavelength-division multiplexing the main signals and the control signals, and a control unit that controls the first optical transceiver based on the control signals received by the second optical transceiver, and the second optical transceiver transmits a single-wavelength response signal in response to the control signal as a burst optical signal. This reduces the number of wavelengths used to control the optical transceivers and reduces the power consumption of the optical transceivers.

[0011] (2) In the above (1), the remote control device may function as a central office optical line terminal in a passive optical network, include the control optical transceiver, and include an OLT function unit that transmits the plurality of control signals as time division multiplexed optical signals, and the optical transceiver may function as a subscriber office optical line terminal in a passive optical network, and include an ONU function unit connected to the second optical transceiver that receives the control signals as time division multiplexed optical signals. This allows remote control of the first optical transceiver by utilizing the OLT function and ONU function of the PON.

[0012] (3) In the above (1) or (2), the optical remote control system according to this embodiment may further include an optical wavelength division multiplexing coupler disposed between the remote control device and the plurality of optical transceivers in the optical communication network, wherein the optical wavelength division multiplexing coupler separates the plurality of main signals from the optical signal by wavelength, and distributes the optical multiplexed signal obtained by wavelength division multiplexing the separated main signals and the control signals to each of the plurality of optical transceivers. This allows the plurality of main signals to be separated from the wavelength division multiplexed signal, and each main signal and control signal to be transmitted to each of the plurality of optical transceivers.

[0013] (4) An optical transceiver according to this embodiment includes a first optical transceiver for transmitting and receiving a main signal, a second optical transceiver for receiving a single-wavelength control signal separated from an optical multiplexed signal in which the main signal and the control signal are wavelength-division multiplexed, and a controller for controlling the first optical transceiver based on the control signal received by the second optical transceiver, wherein the control signal is transmitted from a remote control device, the second optical transceiver receives the transmitted control signal, and the second optical transceiver transmits a single-wavelength response signal in response to the control signal as a burst optical signal. This reduces the number of wavelengths used to control the optical transceiver and reduces the power consumption of the optical transceiver.

[0014] (5) In the above (4), the control signal may be time-division multiplexed with a second control signal for controlling a third optical transceiver included in a second optical transceiver different from the optical transceiver, the optical multiplexed signal may be a multiplexed control signal in which the control signal and the second control signal are time-division multiplexed, and a signal in which the main signal and a second main signal received by the third optical transceiver are wavelength-division multiplexed, the second optical transceiver may convert the multiplexed control signal, which is the received optical signal, into an electrical signal, and the optical transceiver may further include an acquiring unit that acquires an electrical signal corresponding to the control signal from the electrical signal into which the multiplexed control signal is converted. This allows the wavelength of the control signal and the wavelength of the second control signal to be the same in a large-capacity optical communication network in which a main signal and a second main signal are wavelength-division multiplexed, and reduces the number of wavelengths used to control the first optical transceiver.

[0015] (6) In the above (5), the optical transceiver may include an ONU function unit that functions as an optical line terminal in a passive optical network and is connected to the second optical transceiver unit that receives the multiplexed control signal, and the ONU function unit may include the acquisition unit. This allows remote control of the first optical transceiver unit using the OLT function and ONU function of the PON.

[0016] (7) In any one of (4) to (6) above, the control signal may include a control frame used in a passive optical network, whereby the control frame of a passive optical network can be used to control the first optical transceiver.

[0017] (8) In the above (7), the ONU function unit may discard user frames, which are frames different from MPCP frames and the control frames, among the received frames. This reduces the processing load and power consumption of the ONU function unit.

[0018] (9) In the above (7), the ONU function unit may not include a reception buffer for storing user frames, which are frames different from MPCP frames and the control frames, among received frames. This simplifies the configuration of the ONU function unit and reduces the processing load and power consumption of the ONU function unit.

[0019] (10) In any one of (7) to (9) above, the ONU function unit may not include a transmission buffer for storing user frames, which are frames different from MPCP frames and the control frames, among transmission frames. This simplifies the configuration of the ONU function unit and reduces the processing load and power consumption of the ONU function unit.

[0020] (11) In the above (7), the ONU functional unit may include a frame processing unit and a processor, the frame processing unit outputs the received control frame to the processor and transmits the control frame input from the processor, the processor processes a request included in a request frame that is the control frame input from the frame processing unit, generates a response frame that is the control frame including a response to the request and outputs it to the frame processing unit, and the processor goes to sleep after outputting the response frame. This makes it possible to reduce power consumption of the ONU functional unit.

[0021] (12) In the above (7), the frame processing unit may be capable of being powered down, and the processor may power down the frame processing unit during a power-down period based on a sleep period for the processor to sleep. This makes it possible to further reduce the power consumption of the ONU function unit.

[0022] (13) A remote control device according to this embodiment is a remote control device connected to an optical communication network that transmits optical signals in which multiple main signals are wavelength-division multiplexed, and includes: an optical line terminal (OLT) function unit that functions as an optical line terminal (ONU) in a passive optical network and generates control signals to control first optical transceivers provided in multiple optical transceivers connected to the optical communication network; and a control optical transceiver unit that transmits a control signal of a single wavelength so that a second optical transceiver in the optical transceiver, including an ONU function unit that functions as a subscriber-side optical line terminal (ONU) in the passive optical network, receives the control signal, the control optical transceiver unit receiving a response signal of a single wavelength in response to the control signal, the response signal being a signal transmitted as a burst optical signal from the second optical transceiver unit. This reduces the number of wavelengths used to control the optical transceiver and reduces the power consumption of the optical transceiver.

[0023] (14) An optical wavelength division multiplexing coupler according to this embodiment is an optical wavelength division multiplexing coupler arranged between a remote control device and a plurality of optical transceivers in an optical communication network transmitting optical signals obtained by wavelength division multiplexing a plurality of main signals, the optical wavelength division multiplexing coupler including: a first port for receiving a wavelength division multiplexed signal obtained by wavelength division multiplexing the plurality of main signals and control signals transmitted from the remote control device for controlling first optical transmitters and receivers provided in the plurality of optical transceivers; a WDM coupler for separating, by wavelength, the plurality of main signals included in the wavelength division multiplexed signal received by the first port; and a second port for transmitting, to each of the plurality of optical transceivers, an optical multiplexed signal obtained by wavelength division multiplexing each of the plurality of main signals separated by the WDM coupler and the control signals. This makes it possible to reduce the number of wavelengths used to control the optical transceivers and to reduce the power consumption of the optical transceivers.

[0024] (15) An optical remote control method according to this embodiment includes the steps of transmitting a single-wavelength control signal from a remote control device, transmitting an optical multiplexed signal in which a main signal and the control signal are wavelength-division multiplexed over an optical communication network, receiving the main signal separated from the optical multiplexed signal by a first optical transceiver, receiving the control signal separated from the optical multiplexed signal by a second optical transceiver, the control signal having a single wavelength different from that of the main signal, controlling the first optical transceiver based on the control signal received by the second optical transceiver, and transmitting a single-wavelength response signal to the control signal as a burst optical signal by the second optical transceiver. This reduces the number of wavelengths used to control the optical transceiver and reduces the power consumption of the optical transceiver.

[0025] The present disclosure can be realized not only as an optical remote control system having the above-described characteristic configuration, an optical transceiver having the characteristic configuration, a remote control device having the characteristic configuration, an optical wavelength division multiplexing coupler having the characteristic configuration, and a remote control method including the characteristic steps, but also as a computer program for causing the optical transceiver to execute characteristic processes, or as a semiconductor integrated circuit comprising part or all of the optical transceiver. Furthermore, the present disclosure can be realized as a computer program for causing the remote control device to execute characteristic processes, or as a semiconductor integrated circuit comprising part or all of the remote control device. Furthermore, the present disclosure can be realized as a computer program for causing the optical wavelength division multiplexing coupler to execute characteristic processes, or as a semiconductor integrated circuit comprising part or all of the optical wavelength division multiplexing coupler.

[0026] <Details of the embodiments of the present disclosure> Hereinafter, the details of the embodiments of the present disclosure will be described with reference to the drawings. Note that at least some of the embodiments described below may be combined in any manner.

[0027] [1. Optical Communication System] Fig. 1 is a diagram illustrating an example of the configuration of an optical communication system according to an embodiment. The optical communication system 1 illustrated in Fig. 1 connects multiple user devices 40_1, 40_2, 40_3, 40_4, 40_5, 40_6, 40_7, 40_8, and 40_9 via an optical communication network 3, and transmits wavelength-division multiplexed optical signals between the user devices 40_1, 40_2, 40_3, 40_4, 40_5, 40_6, 40_7, 40_8, and 40_9. The optical communication system 1 includes optical wavelength multiplexing switches 10_1, 10_2, and 10_3 and optical transceivers 30_1, 30_2, 30_3, 30_4, 30_5, 30_6, 30_7, 30_8, and 30_9. Hereinafter, the user devices 40_1, 40_2, 40_3, 40_4, 40_5, 40_6, 40_7, 40_8, and 40_9 will be collectively referred to as "user devices 40," and the optical transceivers 30_1, 30_2, 30_3, 30_4, 30_5, 30_6, 30_7, 30_8, and 30_9 will be collectively referred to as "optical transceivers 30." Hereinafter, the optical wavelength multiplexing switch will be collectively referred to as "optical wavelength multiplexing SW," and the optical wavelength multiplexing switches 10_1, 10_2, and 10_3 will be collectively referred to as "optical wavelength multiplexing SW 10."

[0028] The optical transceiver 30 is installed in a user device 40. In FIG. 1, a pair of optical transceivers 30 and a user device 40 are assigned a common sub-number. For example, the user device 40_1 is installed with the optical transceiver 30_1, and the user device 40_2 is installed with the optical transceiver 30_2. While FIG. 1 illustrates a configuration in which one optical transceiver 30 is installed in one user device 40, this is not limiting. Multiple optical transceivers 30 may be installed in one user device 40.

[0029] The optical transceiver 30 includes a wavelength-tunable optical transmitter / receiver. The transmission wavelength of the optical transmitter / receiver can be remotely controlled. The configuration of the optical transceiver 30 will be described later.

[0030] Each optical transceiver 30 is assigned a wavelength. The optical transceivers 30 transmit optical signals (main signals) with the assigned wavelengths. For example, different wavelengths are assigned to the optical transceivers 30_1, 30_2, 30_3, 30_4, 30_5, 30_6, 30_7, 30_8, and 30_9. Different wavelengths are assigned to the optical transceivers 30_1, 30_2, and 30_3, at least in which transmission signals are multiplexed. Different wavelengths are also assigned to the optical transceivers 30_4, 30_5, and 30_6, and different wavelengths are also assigned to the optical transceivers 30_7, 30_8, and 30_9. However, the same wavelength may be assigned to optical transceivers 30 in which transmission signals are not multiplexed. The wavelength of the main signal is selected from a wavelength range excluding wavelengths for control signals, which will be described later.

[0031] The user equipment 40 is located in a user's home or a user's facility. The user equipment 40 may be, for example, a relay device such as a router for connecting a user's LAN (Local Area Network) to the optical communication network 3. For example, a first user equipment 40 (e.g., user equipment 40_1) is an RU (Radio Unit) in a mobile fronthaul (MFH), and a second user equipment 40 (e.g., user equipment 40_4) that is an opposite device of the first user equipment is a DU (Distributed Unit).

[0032] For example, the optical communication network 3 is an APN that transmits optical signals end-to-end. The optical communication network 3 includes, for example, a metro network 3A connected to a telecommunications carrier's base within a city, and an access network 3B connected to a user base (a user home or a user facility).

[0033] The optical wavelength multiplexing SW 10 is an optical gateway that connects the metro network 3A and the access network 3B and relays optical signals between the metro network 3A and the access network 3B. In the metro network 3A, the optical wavelength multiplexing SWs 10_1, 10_2, and 10_3 are interconnected by a plurality of optical transmission paths 60_1, 60_2, and 60_3. The metro network 3A is a two-core transmission network, and the optical transmission paths 60_1, 60_2, and 60_3 are two-core optical transmission paths (the transmission directions of the two cores are opposite to each other). Hereinafter, the two-core optical transmission paths are also referred to as "two-core transmission paths." For example, the metro network 3A is a ring topology network, and a specific example is a ROADM (Reconfigurable Optical Add / Drop Multiplexer). However, the configuration of the metro network 3A is not limited to this and may be a mesh topology network. The optical transmission paths 61_1, 61_2, and 61_3 of the access network 3B are single-core optical transmission paths (one core for two-way multiplex communication). Hereinafter, a single-core optical transmission path will also be referred to as a "single-core transmission path." In single-core transmission, different wavelengths are assigned to the upstream main signal and the downstream main signal. The optical transmission paths 62_1, 62_2, and 62_3 are two-core transmission paths. However, the entire access network 3B may be a network of single-core transmission paths or a network of two-core transmission paths.

[0034] The optical wavelength multiplexing SW 10 wavelength-division multiplexes optical signals transmitted from each user device 40, or demultiplexes a wavelength-division multiplexed signal obtained by combining the optical signals transmitted from each user device 40, and forwards the optical signal thus obtained to a path on the metro network 3A side corresponding to the wavelength. Furthermore, the optical wavelength multiplexing SW 10 wavelength-division multiplexes multiple optical signals transmitted from the metro network 3A side, or demultiplexes a wavelength-division multiplexed signal transmitted from the metro network 3A side, and forwards the optical signal thus obtained to a path on the access network 3B side corresponding to the wavelength. The optical wavelength multiplexing SW 10 multiplexes or demultiplexes optical signals without converting them to electrical signals within the device, and forwards them to the destination path.

[0035] The optical wavelength multiplexing SW 10_1 will be described below as a representative, but the same applies to the optical wavelength multiplexing SWs 10_2 and 10_3. The optical wavelength multiplexing SW 10_1 has a plurality of ports MP_1 and MP_2 on the metro network side (hereinafter also referred to as "metro side ports") and a plurality of ports AP_1, AP_2, and AP_3 on the access network side (hereinafter also referred to as "access side ports").

[0036] Each of the metro-side ports MP_1 and MP_2 includes an output interface and an input interface. The output interface of the metro-side port MP_1 is connected to a first transmission line of the two-core transmission line 60_1 (a transmission line from the optical wavelength multiplexing SW 10_1 to the optical wavelength multiplexing SW 10_2), and the input interface of the metro-side port MP_1 is connected to a second transmission line of the two-core transmission line 60_1 (a transmission line from the optical wavelength multiplexing SW 10_2 to the optical wavelength multiplexing SW 10_1). The output interface of the metro-side port MP_2 is connected to a first transmission line of the two-core transmission line 60_3 (a transmission line from the optical wavelength multiplexing SW 10_1 to the optical wavelength multiplexing SW 10_3), and the input interface of the metro-side port MP_2 is connected to a second transmission line of the two-core transmission line 60_3 (a transmission line from the optical wavelength multiplexing SW 10_3 to the optical wavelength multiplexing SW 10_1).

[0037] The access side ports AP_1, AP_2, and AP_3 are connected to the optical wavelength division multiplexing coupler 20 (or the optical transceiver 30) via single-core transmission lines 61_1, 61_2, and 61_3, respectively. As shown in Fig. 1, one access side port AP_1 of the optical wavelength division multiplexing SW 10_1 is connected to the optical wavelength division multiplexing coupler 20_1 via the single-core transmission line 61_1.

[0038] The optical wavelength multiplexing SW 10_1 includes a wavelength selective switch (hereinafter also referred to as a “WSS”) 14 and a wavelength multiplexing / demultiplexing unit (hereinafter also referred to as an “Add / Drop”) 15.

[0039] The WSS 14 is connected to each of the metro side ports MP_1 and MP_2 by optical transmission lines, and is also connected to the Add / Drop 15 by optical transmission lines. The Add / Drop 15 is connected to each of the access side ports AP_1, AP_2, and AP_3 by multiple optical transmission lines.

[0040] WSS 14 determines whether to pass or drop optical signals input to the input interface of metro side port MP_1 for each wavelength, and outputs optical signals of the wavelengths to be passed to the output interface of metro side port MP_2. WSS 14 outputs optical signals of the wavelengths to be dropped to Add / Drop 15. WSS 14 determines whether to pass or drop optical signals input to the input interface of metro side port MP_2 for each wavelength, and outputs optical signals of the wavelengths to be passed to the output interface of metro side port MP_1. WSS 14 outputs optical signals of the wavelengths to be dropped to Add / Drop 15.

[0041] The WSS 14 outputs the optical signal input from the Add / Drop 15 to the output interface of the metro side port MP_1 or the output interface of the metro side port MP_2 for each wavelength.

[0042] The Add / Drop 15 separates the optical signals input from the WSS 14 by wavelength and outputs the optical signals of each wavelength to the access side ports AP_1, AP_2, or AP_3. Furthermore, the Add / Drop 15 wavelength-multiplexes the optical signals input from the access side ports AP_1, AP_2, and AP_3 and outputs a wavelength division multiplexed signal (hereinafter also referred to as a "WDM signal") to the WSS 14.

[0043] 1, an optical wavelength multiplexing coupler 20_1 is disposed between the optical wavelength multiplexing SW 10_1 and the optical transceivers 30_1, 30_2, and 30_3. An optical wavelength multiplexing coupler 20_2 is disposed between the optical wavelength multiplexing SW 10_2 and the optical transceivers 30_4, 30_5, and 30_6. An optical wavelength multiplexing coupler 20_3 is disposed between the optical wavelength multiplexing SW 10_3 and the optical transceivers 30_7, 30_8, and 30_9. Hereinafter, the optical wavelength multiplexing couplers 20_1, 20_2, and 20_3 will also be collectively referred to as "optical wavelength multiplexing couplers 20."

[0044] The port of the optical wavelength division multiplexing SW 10_1 on the access network 3B side is connected to single-core transmission lines 61_1, 61_2, and 61_3 formed of optical fiber. The single-core transmission line 61_1 is connected to the optical wavelength division multiplexing coupler 20_1. The optical wavelength division multiplexing coupler 20_1 is connected to optical transceivers 30_1, 30_2, and 30_3 via two-core transmission lines 62_1, 62_2, and 62_3. The optical wavelength division multiplexing SWs 10_2 and 10_3 are also connected to the optical wavelength division multiplexing couplers 20_2 and 20_3 and optical transceivers 30_4, 30_5, 30_6, 30_7, 30_8, and 30_9 via optical transmission lines, but the connection relationships between the respective nodes are the same as those described above, so a description thereof will be omitted.

[0045] The optical wavelength multiplexing coupler 20 separates the WDM signal transferred by the optical wavelength multiplexing SW 10 into individual wavelengths and transfers the separated optical signals to the optical transceivers 30 corresponding to each wavelength. The optical wavelength multiplexing coupler 20 wavelength-multiplexes the optical signals transmitted from each optical transceiver 30 and transfers the resulting WDM signal to the optical wavelength multiplexing SW 10. The optical wavelength multiplexing coupler 20 multiplexes or separates the optical signals without converting them into electrical signals within the device and transfers them to the destination path. Details of the optical wavelength multiplexing coupler 20 will be described later.

[0046] The optical transceiver 30 and the optical wavelength multiplexing SW 10 may be connected without the optical wavelength multiplexing coupler 20. Alternatively, the optical transceiver 30 and the optical wavelength multiplexing SW 10 may be connected via multiple optical wavelength multiplexing couplers 20. In this case, one wavelength width multiplexed by the upper-stage optical wavelength multiplexing coupler 20 (i.e., closer to the optical wavelength multiplexing SW 10) includes the wavelength range of the lower-stage optical wavelength multiplexing coupler 20 (i.e., closer to the optical transceiver 30). The optical wavelength multiplexing coupler 20 may be a power coupler. However, in this case, since the optical transceiver 30 receives main signals of multiple wavelengths, the optical transceiver 30 further includes a wavelength selection filter for selecting and receiving only the corresponding wavelengths.

[0047] [2. Optical Remote Control Systems] The optical communication system 1 includes optical remote control systems 2_1, 2_2, and 2_3. The optical remote control system 2_1 is a system for remotely controlling optical transceivers 30_1, 30_2, and 30_3, and includes an optical wavelength multiplexing SW 10_1 and the optical transceivers 30_1, 30_2, and 30_3. The optical remote control system 2_2 is a system for remotely controlling optical transceivers 30_4, 30_5, and 30_6, and includes an optical wavelength multiplexing SW 10_2 and the optical transceivers 30_4, 30_5, and 30_6. The optical remote control system 2_3 is a system for remotely controlling optical transceivers 30_7, 30_8, and 30_9, and includes an optical wavelength multiplexing SW 10_3 and the optical transceivers 30_7, 30_8, and 30_9. Hereinafter, the optical remote control systems 2_1, 2_2, and 2_3 will be collectively referred to as the “optical remote control system 2.” The optical remote control system 2 may include a management device 50.

[0048] The optical remote control system 2 remotely controls the optical transceiver 30 using a TDM-PON (Time Division Multiplexing-PON). More specifically, the optical remote control system 2 according to this embodiment remotely controls the optical transceiver 30 using an EPON (Ethernet PON) defined in IEEE 802.3ah, except for specifications related to transmission and reception wavelengths. Each optical wavelength multiplexing SW 10 includes an OLT function unit (referred to as "OLT" in FIG. 1) 11_1, 11_2, and 11_3. Hereinafter, the OLT function units 11_1, 11_2, and 11_3 are collectively referred to as the "OLT function unit 11." In FIG. 1, a common subnumber is assigned to a pair of the optical wavelength multiplexing SW 10 and the OLT function unit 11.

[0049] Each optical transceiver 30 includes one of the ONU functional units (referred to as "ONU" in FIG. 1) 31_1, 31_2, 31_3, 31_4, 31_5, 31_6, 31_7, 31_8, and 31_9. Hereinafter, the ONU functional units 31_1, 31_2, 31_3, 31_4, 31_5, 31_6, 31_7, 31_8, and 31_9 are collectively referred to as the "ONU functional unit 31." In FIG. 1, a pair of optical transceiver 30 and ONU functional unit 31 is assigned a common subnumber.

[0050] The management device 50 centrally manages the optical transceivers 30_1, 30_2, 30_3, 30_4, 30_5, 30_6, 30_7, 30_8, and 30_9. The management device 50 is communicatively connected to the optical wavelength multiplexing SWs 10_1, 10_2, and 10_3 via transmission paths 70_1, 70_2, and 70_3 (shown by dashed lines in the figure) that are based on known techniques such as electrical signal lines, optical signal lines, and wireless networks. For example, the management device 50 and the optical wavelength multiplexing SWs 10_1, 10_2, and 10_3 can communicate with each other using a communication protocol such as the Ethernet protocol ("Ethernet" is a registered trademark).

[0051] 2A is a diagram showing a first example of the configuration of an optical remote control system according to an embodiment. In FIG. 2A, an example of the configuration of an optical remote control system 2_1 is shown as a representative example, but the same applies to optical remote control systems 2_2 and 2_3.

[0052] The optical wavelength multiplexing SW 10_1 includes an OLT function unit 11_1, a WSS 14, and an Add / Drop 15, as well as a SW control unit 12, a remote optical transceiver control unit 13 (hereinafter, "transceiver" may also be referred to as "TRx"), and a control signal multiplexing unit 16.

[0053] The SW control unit 12 is connected to the management device 50 via a transmission path 70_1. The SW control unit 12 is further connected to a remote optical TRx control unit 13. The SW control unit 12 can communicate with the management device 50 using a communication protocol such as the Ethernet protocol. The management device 50 transmits control information including the transmission path and wavelength of the optical signal, and the SW control unit 12 receives the control information from the management device 50. The control information includes information for setting the transmission wavelength of the optical transceiver 30.

[0054] The SW control unit 12 is configured by a processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), etc. The SW control unit 12 analyzes the received control information and sets the WSS 14 and the Add / Drop 15 according to the transmission path and wavelength included in the control information.

[0055] The remote optical TRx control unit 13 is connected to the OLT function unit 11_1. In Fig. 2A, optical connections between multiple elements are indicated by solid lines, electrical connections between multiple elements are indicated by dashed lines, and connections between multiple elements regardless of the connection form (optical connection, electrical connection, etc.) are indicated by dashed and dotted lines.

[0056] The remote optical TRx control unit 13 is configured with a processor, an ASIC, an FPGA, etc. The remote optical TRx control unit 13 can analyze the received control information and convert it into a command for controlling the optical transceiver 30.

[0057] The OLT functional unit 11_1 is configured with a processor, an ASIC, an FPGA, etc., and includes an optical transceiver 111. Note that two or three of the SW control unit 12, the remote optical TRx control unit 13, and the OLT functional unit 11_1 may be configured with one processor, ASIC, FPGA, etc. The optical transceiver 111 may be provided outside the OLT functional unit 11_1 and connected to the OLT functional unit 11_1.

[0058] The OLT functional unit 11_1 performs PON communication with the subordinate ONU functional units 31_1, 31_2, and 31_3 using optical signals (hereinafter also referred to as "control signals") of a predetermined control wavelength. Hereinafter, the direction from the optical wavelength multiplexing SW 10_1 (OLT functional unit 11_1) to the optical transceivers 30_1, 30_2, and 30_3 (ONU functional units 31_1, 31_2, and 31_3) will be referred to as the "downstream direction," and the direction from the optical transceivers 30_1, 30_2, and 30_3 (ONU functional units 31_1, 31_2, and 31_3) to the optical wavelength multiplexing SW 10_1 (OLT functional unit 11_1) will be referred to as the "upstream direction." The control wavelength is a wavelength different from the wavelength of the main signal. The control wavelength is, for example, 1490 nm as the transmission wavelength of the OLT function unit 11_1 (hereinafter also referred to as the "downstream control wavelength") and 1310 nm as the reception wavelength of the OLT function unit 11_1 (hereinafter also referred to as the "upstream control wavelength").

[0059] The OLT functional unit 11_1 communicates with the ONU functional units 31_1, 31_2, and 31_3 individually and controls the subordinate optical transceivers 30_1, 30_2, and 30_3 individually. Therefore, a multiplexed control signal, which is an optical signal obtained by time-division multiplexing a control signal for controlling the ONU functional unit 31_1, a control signal for controlling the ONU functional unit 31_2, and a control signal for controlling the ONU functional unit 31_3, is transmitted between the OLT functional unit 11_1 and the ONU functional units 31_1, 31_2, and 31_3.

[0060] A control signal multiplexing unit 16 is disposed in the optical transmission path between the Add / Drop 15 and the access-side ports AP_1, AP_2, and AP_3. The WSS 14 and the Add / Drop 15 handle optical signals as two-core transmission, while the control signal multiplexing unit 16 handles optical signals as single-core transmission. The Add / Drop 15 converts between single-core transmission and two-core transmission. Three single-core optical transmission paths 61_1, 61_2, and 61_3 extend from the Add / Drop 15, and the control signal multiplexing unit 16 includes WDM couplers 16_1, 16_2, and 16_3 disposed in the respective optical transmission paths 61_1, 61_2, and 61_3. The downstream multiplexed control signal output from the OLT function unit 11_1 is distributed to each branch line by optical couplers (power couplers) (not shown) disposed on the transmission path extending from the optical transceiver 111. The WDM couplers 16_1, 16_2, and 16_3 multiplex the distributed downstream multiplexed control signals into downstream main signals transmitted through the respective transmission paths 61_1, 61_2, and 61_3. The single-core transmission paths 61_1, 61_2, and 61_3 extending from the control signal multiplexing unit 16 extend from the access-side ports AP_1, AP_2, and AP_3 to the outside from the optical wavelength multiplexing SW 10_1.

[0061] Wavelength division multiplexed signals of downstream main signals and downstream multiplex control signals (hereinafter also referred to as "downstream optical multiplexed signals") are output from the access side ports AP_1, AP_2, and AP_3 of the optical wavelength multiplexing SW 10_1.

[0062] The optical wavelength division multiplexing coupler 20_1 includes WDM couplers 21, 22A, 22B, 24A_1, 24A_2, 24A_3, 24B_1, 24B_2, and 24B_3, and optical couplers 23A and 23B.

[0063] A single-core transmission line 61_1 is introduced into the optical wavelength division multiplexing coupler 20_1. WDM couplers 22A and 22B are arranged midway along the single-core transmission line 61_1. The WDM coupler 22A separates a downstream main signal (a WDM signal of three systems of downstream main signals) and a downstream multiplex control signal from the downstream optical multiplexed signal transmitted through the single-core transmission line 61_1. The downstream main signal is input to the WDM coupler 21. The WDM coupler 21 separates the input downstream main signal by wavelength and distributes the separated main signals of each system to each branch line.

[0064] The WDM coupler 21 is connected to two-core transmission lines 62_1, 62_2, and 62_3. Each of the two-core transmission lines 62_1, 62_2, and 62_3 includes a downstream optical transmission line 62_1A, 62_2A, or 62_3A (hereinafter also referred to as a "downstream transmission line") and an upstream optical transmission line 62_1B, 62_2B, or 62_3B (hereinafter also referred to as an "upstream transmission line"). The WDM coupler 21 outputs three downstream main signals, obtained by separating the downstream WDM signal, to the downstream transmission lines 62_1A, 62_2A, and 62_3A, respectively.

[0065] The downstream multiplexed control signal separated by the WDM coupler 22A is distributed to multiple systems by an optical coupler 23A. WDM couplers 24A_1, 24A_2, and 24A_3 are arranged in the downstream transmission paths 62_1A, 62_2A, and 62_3A, respectively. The downstream main signal output from the WDM coupler 21 and the downstream multiplexed control signal output from the optical coupler 23A are input to the WDM couplers 24A_1, 24A_2, and 24A_3, respectively. Each of the WDM couplers 24A_1, 24A_2, and 24A_3 multiplexes the input downstream main signal and downstream multiplexed control signal, and outputs the multiplexed signal as a WDM signal (optical multiplexed signal).

[0066] The optical transceiver 30_2 includes an optical transceiver for main signals (hereinafter also referred to as "U-TRx") 301 and an optical transceiver for control signals (hereinafter also referred to as "C-TRx") 311. The U-TRx 301 is a wavelength-tunable optical transceiver. More specifically, the U-TRx 301 includes a wavelength-tunable optical transmitter and an optical receiver capable of receiving optical signals with a specific range of wavelengths. The C-TRx 311 includes an optical transmitter capable of transmitting an optical signal with an upstream control wavelength and an optical receiver capable of receiving an optical signal with a downstream control wavelength. The U-TRx 301 is an example of a "first optical transceiver," and the C-TRx 311 is an example of a "second optical transceiver." Note that the optical receiver of the U-TRx 301 may be a receiving wavelength-selective optical receiver.

[0067] The optical transceiver 30_2 includes a port PA for receiving an optical signal and a port PB for transmitting an optical signal. WDM couplers 304A and 304B are disposed along the optical transmission lines extending from the ports PA and PB, respectively.

[0068] The downstream WDM signal output from the optical wavelength division multiplexing coupler 20_1 and transmitted through the downstream transmission path 62_2A is input to the WDM coupler 304A from port PA of the optical transceiver 30_2. The WDM coupler 304A separates the downstream WDM signal into a downstream main signal and a downstream multiplexed control signal. The downstream main signal output from the WDM coupler 304A is received by the U-TRx 301, and the downstream multiplexed control signal output from the WDM coupler 304A is received by the C-TRx 311.

[0069] The optical transceiver 30_2 obtains a control signal (frame) addressed to itself from the downstream multiplexed control signal and executes the command contained in the control signal. The C-TRx 311 transmits an upstream control signal carrying a frame containing the execution result. The optical transceivers 30_1, 30_2, and 30_3 transmit frames at different times. The upstream main signal transmitted from the U-TRx 301 and the upstream control signal transmitted from the C-TRx 311 are input to the WDM coupler 304B. The WDM coupler 304B multiplexes the upstream main signal and the upstream control signal and outputs an upstream WDM signal. The upstream WDM signal is output from port PB to the upstream transmission path 62_2B.

[0070] Within the optical wavelength division multiplexing coupler 20_1, WDM couplers 24B_1, 24B_2, and 24B_3 are arranged in the upstream transmission paths 62_1B, 62_2B, and 62_3B, respectively. The upstream WDM signals transmitted through the upstream transmission paths 62_1B, 62_2B, and 62_3B, respectively, are input to the WDM couplers 24B_1, 24B_2, and 24B_3. The WDM couplers 24B_1, 24B_2, and 24B_3 each separate an upstream main signal and an upstream control signal from the upstream WDM signal. Each of the three upstream main signals is input to a WDM coupler 21. The WDM coupler 21 multiplexes the input three upstream main signals and outputs the WDM signal to the single-core transmission path 61_1.

[0071] The three upstream control signals output from the WDM couplers 24B_1, 24B_2, and 24B_3 are input to the optical coupler 23B. The optical coupler 23B multiplexes the three upstream control signals. As described above, the optical transceivers 30_1, 30_2, and 30_3 transmit frames at different timings, and therefore the optical coupler 23B time-division multiplexes the three upstream control signals.

[0072] The WDM coupler 22B multiplexes the upstream WDM signal output from the WDM coupler 21 with the upstream multiplex control signal (a TDM signal of three control signals) output from the optical coupler 23B, and outputs a wavelength division multiplexed signal (hereinafter also referred to as an "upstream optical multiplexed signal") in which the three main signal WDM signals and the upstream multiplex control signal are multiplexed. The upstream optical multiplexed signal is transmitted through the single-core transmission line 61_1 and input to the access-side port AP_1 of the optical wavelength multiplexing SW 10_1. Similarly, the upstream optical multiplexed signal transmitted through the single-core transmission line 61_2 is input to the access-side port AP_2, and the upstream optical multiplexed signal transmitted through the single-core transmission line 61_3 is input to the access-side port AP_3.

[0073] The control signal multiplexing unit 16 demultiplexes the upstream optical multiplexed signals transmitted through the single-core transmission lines 61_1, 61_2, and 61_3, respectively, into an upstream main signal and an upstream multiplexed control signal using WDM couplers 16_1, 16_2, and 16_3. The upstream multiplexed control signals output from the WDM couplers 16_1, 16_2, and 16_3 are multiplexed by an optical coupler (not shown) and input to the OLT function unit 11_1. The OLT function unit 11_1 extracts the execution results of commands from the upstream multiplexed control signals and outputs the extracted execution results of commands to the remote optical TRx control unit 13. The remote optical TRx control unit 13 generates response information including the execution results of commands. The remote optical TRx control unit 13 outputs the response information to the SW control unit 12. The SW control unit 12 transmits the input response information to the management device 50 either directly or together with responses to the setting commands of the WSS 14 and the Add / Drop 15 .

[0074] The optical transmission paths 62_1, 62_2, and 62_3 downstream from the optical wavelength division multiplexing coupler 20_1 may be single-core transmission paths. Fig. 2B is a diagram showing a second example of the configuration of the optical remote control system according to the embodiment. Fig. 2B shows an example in which the optical transmission paths 62_1, 62_2, and 62_3 are single-core transmission paths.

[0075] 2B, the WDM coupler 21A is connected to single-core transmission lines 62_1, 62_2, and 62_3. The WDM coupler 21A outputs three systems of downstream main signals, obtained by separating the downstream WDM signal, to the single-core transmission lines 62_1, 62_2, and 62_3, respectively. The downstream multiplexed control signal output from the optical coupler 23A is input to WDM couplers 24A_1, 24A_2, and 24A_3 arranged in the single-core transmission lines 62_1B, 62_2B, and 62_3B. Each of the WDM couplers 24A_1, 24A_2, and 24A_3 multiplexes the input downstream main signal and downstream multiplexed control signal, and outputs the multiplexed signal as a WDM signal.

[0076] Downstream WDM signals and upstream WDM signals of the corresponding systems are multiplexed and transmitted through each of the single-core transmission lines 62_1, 62_2, and 62_3. The optical transceiver 30_2 has one port PT connected to the single-core transmission line 62_2. In the optical transceiver 30_2, a WDM coupler 304C is connected to the single-core optical transmission line extending from the port PT. The WDM coupler 304C converts between single-core transmission and dual-core transmission. A dual-core optical transmission line extends from the WDM coupler 304C to the U-TRx 311, and WDM couplers 304A and 304B are disposed midway along each optical transmission line.

[0077] The WDM coupler 304C extracts the downstream WDM signal from the wavelength-multiplexed signal of the upstream WDM signal and the downstream WDM signal, and outputs the extracted downstream WDM signal to the WDM coupler 304A. Furthermore, the upstream WDM signal output from the WDM coupler 304B is input to the WDM coupler 304C, which outputs the upstream WDM signal to the single-core transmission line 62_2 so as to wavelength-multiplex it with the downstream WDM signal.

[0078] The WDM couplers 24B_1, 24B_2, and 24B_3 arranged in the single-core transmission lines 62_1, 62_2, and 62_3, respectively, separate the upstream main signal and the upstream control signal from the upstream WDM signal. Each of the three upstream main signals is input to the WDM coupler 21A. The WDM coupler 21A multiplexes the input three upstream main signals and outputs the WDM signal to the single-core transmission line 61_1.

[0079] The three upstream control signals output from the WDM couplers 24B_1, 24B_2, and 24B_3 are input to the optical coupler 23B, which multiplexes the input three upstream control signals.

[0080] The WDM coupler 22B combines the upstream WDM signal output from the WDM coupler 21A with the upstream multiplexed control signal (a TDM signal of three control signals) output from the optical coupler 23B, and outputs an upstream optical multiplexed signal combined with the three main signal WDM signals and the upstream multiplexed control signal.

[0081] 3. Optical Transceiver FIG. 3 is a diagram illustrating an example of the hardware configuration of an optical transceiver.

[0082] In addition to the above-mentioned ONU function unit 31, U-TRx 301, and C-TRx 311, the optical transceiver 30 includes a microcontroller unit (MCU) 32, a drive circuit 302 for the U-TRx 301, a digital signal processor (DSP) 303, and a laser diode driver (LDD) and limiting amplifier (LA) unit (LDD / LA) 312.

[0083] The DSP 303 is connected to an input / output terminal for a main signal (electrical signal) of the user equipment 40. The DSP 303 performs signal processing such as frame processing on the upstream main signal output from the output terminal of the user equipment 40.

[0084] The output terminal of the DSP 303 is connected to the input terminal of the driver circuit 302. For example, the optical transmitter of the U-TRx 301 converts an electrical signal into an optical signal using an electroabsorption modulated laser (EAM). The driver circuit 302 is connected to the U-TRx 301 and drives and controls the EAM in accordance with the electrical signal output from the DSP 303. This causes the U-TRx 301 to output an optical signal corresponding to the electrical signal output by the DSP 303.

[0085] The optical receiver of the U-TRx 301 converts an optical signal into a current signal using, for example, a pin photodiode (pin-PD). The optical receiver includes a transimpedance amplifier (TIA), which converts the current signal output from the pin-PD into a voltage signal.

[0086] The input terminal of the DSP is connected to the optical receiver of the U-TRx 301, and the electrical signal (downstream main signal) output from the U-TRx 301 is input to the DSP 303. The DSP 303 performs signal processing such as frame processing on the downstream main signal output from the U-TRx 301. The downstream main signal processed by the DSP 303 is output from the DSP 303 to the input terminal of the user equipment.

[0087] On the other hand, the C-TRx 311 is connected to the LDD / LA 312. More specifically, the optical transmitter of the C-TRx 311 is connected to the LDD, and the optical receiver is connected to the LA.

[0088] The optical receiver of the C-TRx 311 converts an optical signal (downstream multiplex control signal) into a current signal using, for example, a pin-PD, and converts the current signal output from the pin-PD into a voltage signal using a TIA.

[0089] An electrical signal is output from the optical receiver to the LA. The LA adjusts the output amplitude of the TIA, which varies depending on the strength of the received optical signal, to produce an electrical signal of the appropriate amplitude. The LDD / LA 312 is connected to the ONU function unit 31, and the electrical signal output from the LA is input to the ONU function unit 31.

[0090] The ONU function unit 31 is configured by, for example, an FPGA. The FPGA configuring the ONU function unit 31 includes a circuit that functions as a frame processing unit 313, a processor 314, and a memory 315.

[0091] The frame processing unit 313 performs frame processing on the downstream multiplexed control signal output from the LA. The frame processing unit 313 is a PON Media Access Control (MAC) circuit, and can generate PON frames specified in IEEE 802.3ah and acquire information from PON frames. More specifically, the frame processing unit 313 can generate and process PON OAM frames. In a specific example, the frame processing unit 313 can handle PON OAM frames.

[0092] The frame processing unit 313 extracts (acquires) a downstream control signal addressed to its own device from the downstream multiplexed control signal received by the C-TRx 311, more specifically, a frame addressed to its own device. The frame processing unit 313 is an example of an "acquisition unit." More specifically, each ONU function unit 31 is assigned identification information called an LLID (Logical Link ID). The LLID is stored in the frame preamble. The frame processing unit 313 acquires the LLID from the frame preamble and identifies frames addressed to its own device by determining whether the LLID matches the LLID of its own device or a broadcast LLID. The frame processing unit 313 acquires frames determined to be addressed to its own device based on the LLID, and discards frames addressed to other devices.

[0093] The frame processing unit 313 acquires control information from the extracted frame. The frame processing unit 313 is connected to the processor 314, and the processor 314 is connected to the memory 315. The frame processing unit 313 outputs the acquired control information to the processor 314.

[0094] The MCU 32 includes a processor 321, a memory 322, a D / A converter (DAC) 323, and an A / D converter (ADC) 324. The processor 321 functions as a control unit 330. The processor 314 of the ONU function unit 31 outputs control information input from the frame processing unit 313 to the processor 321 (control unit 330). The control unit 330 converts the control information into a command. The control unit 330 executes the obtained command and obtains the execution result.

[0095] The control unit 330 is capable of reading the value of a specified register. The registers that the control unit 330 can read and write are mapped in a unified manner, but may be actually one memory (e.g., memory 322) or multiple memories. For example, the first area of ​​the register may be configured by memory 322, and the second area may be configured by memory within U-TRx 301. When an instruction to read the value of a specified register is given, the control unit 330 reads the value from the specified register. The control unit 330 outputs the read value to the processor 314 as a result of executing the instruction.

[0096] The control unit 330 is capable of writing a specified value to a specified register. When a write command for a specified register is given, the control unit 330 writes the specified value to the specified register. The control unit 330 outputs (echoes back) the written value to the processor 314 as a result of executing the command.

[0097] For example, when the control unit 330 writes a value to a register for controlling the wavelength of the U-TRx 301, it outputs the written value (digital value) to the DAC 323 and DSP 303. The DAC 323 is connected to the U-TRx 301 and the driver circuit 302. The DAC 323 and DSP 303 are used to configure the U-TRx 301. The DSP 303 configures the modulation method of the U-TRx 301 according to the input digital value. The DAC 323 converts the input digital value to an analog value and outputs the analog value to the U-TRx 301. The U-TRx 301 configures the output wavelength (transmission wavelength), crosspoint, TIA band, and electrical signal amplitude of the optical transmitter according to the input analog value. The crosspoint is the point at which the optical signal waveform changes from 0 to 1. The TIA band is the frequency band of the TIA that converts the current signal output from the pin-PD into a voltage signal. The electrical signal amplitude is the amplitude of the electrical signal that is converted into an optical signal in the optical transceiver 30 on the transmitting side.

[0098] The ADC 324 is connected to the U-TRx 301 and the drive circuit 302. For example, when the control unit 330 writes a value to a register for monitoring the temperature of the U-TRx 301, the voltage (analog value) of the thermistor circuit for measuring the temperature of the U-TRx 301 is read by the ADC 324 and output as a digital value. The control unit 330 calculates the temperature from the read voltage and outputs the calculation result to the processor 314. This allows the management device 50 to monitor the temperature of the U-TRx 301. In another example, when the control unit 330 writes a value to a register for monitoring the drive current of the U-TRx 301, the drive current value (analog value) of the U-TRx 301 is read by the ADC 324 and output as a digital value. The control unit 330 outputs the read drive current value to the processor 314. This allows the management device 50 to monitor the drive current value of the U-TRx 301.

[0099] The processor 314 receives the command execution result output from the control unit 330 and outputs the received command execution result to the frame processing unit 313 .

[0100] The frame processing unit 313 generates a frame including the result of the command execution, and outputs the generated frame to the LDD as an upstream control signal (voltage signal).

[0101] The LDD converts the voltage signal into a current signal and outputs the resulting current signal to the optical transmitter of the C-TRx 311. This drives the laser of the optical transmitter, and a burst optical signal corresponding to the current signal is output (transmitted).

[0102] 4. OAM Frames A PON frame is used in communication between the OLT function unit 11 and the ONU function unit 31. More specifically, a PON OAM frame defined in IEEE 802.3ah is used. In a specific example, an extended OAM frame is used.

[0103] FIG. 4 is a diagram showing an example of a frame format of an extended OAM frame.

[0104] The extended OAM frame (hereinafter simply referred to as "OAM frame") includes the following fields: destination address (DA), source address (SA), length / type, subtype, flags, code, vendor code (OUI: Organizationally Unique Identifier), type, ID, error status, PDU data TLV, end of TLV, pad, and FCS (frame check sequence).

[0105] The DA field of the OAM frame stores a multicast address, and the SA field stores the MAC address of the OLT function unit 11 in the case of a downstream frame, and the MAC address of the ONU function unit 31 in the case of an upstream frame.

[0106] The Length / Type field stores the frame length and “Slow Protocol.” The SubType field stores “OAM.”

[0107] The Code field stores a code (0xFE) indicating that the frame is an extended OAM frame. The OUI field stores the code of the vendor that defined the extended OAM frame.

[0108] The Type field stores the type of the extended OAM frame. The types of extended OAM frames include at least "GetRequest," "GetResponse," "SetRequest," and "SetResponse." The SetRequest frame is a frame used by the OLT functional unit 11 to request the ONU functional unit 31 to configure the optical transceiver 30. As a specific example, the SetRequest frame stores a specified address of a control register of the optical transceiver 30 and data to be written to the specified address. The SetResponse frame is a frame used by the ONU functional unit 31 to respond to a configuration request from the OLT functional unit 11. As a specific example, the SetResponse frame stores the address of the control register to which data has been written and the data written to the address. GetRequest is a frame used by the OLT functional unit 11 to request the ONU functional unit 31 to acquire the status of the optical transceiver 30. As a specific example, the GetRequest frame stores a specified address of a control register of the optical transceiver 30. GetResponse is a frame used by the ONU functional unit 31 to respond to a status acquisition request from the OLT functional unit 11. As a specific example, the GetResponse frame stores the address of the control register from which data was read and the data read from that address.

[0109] The ID field is a field for matching a pair of a request and a response. In a specific example, an arbitrary value (ID) is stored in the ID field of a request frame. The same value (ID) as that of the request is stored in the ID field of a response frame.

[0110] The Error Status field stores a code indicating whether the request was successful or failed in the response frame.

[0111] The PDU Data TLV field is a field for storing a control command (i.e., a setting request or a status acquisition request) and an execution result (i.e., a response to the request) for the optical transceiver 30, and includes subfields for Type, Length, and Value.

[0112] The Type subfield stores a code indicating the type of the frame (SetRequest, SetResponse, GetRequest, or GetResponse). The Length subfield stores the data length of the PDU Data TLV field. The Value subfield stores the address of the control register of the optical transceiver 30 and the data at that address. Specifically, the Value subfield of the SetRequest frame stores the address of the control register to be written and the data to be written to that address. The Value subfield of the SetResponse frame stores the address of the control register to be written and the data written to that address. The Value subfield of the GetRequest frame stores the address of the control register to be read and a predetermined value (reserved value). The Value subfield of the GetResponse frame stores the address of the control register to be read and the data read from that address.

[0113] 5. Operation of Optical Remote Control System The operation of the optical remote control system 2_1 will be described below as a representative example. Note that the operations of the optical remote control systems 2_2 and 2_3 are similar to the operation of the optical remote control system 2_1.

[0114] Fig. 5 is a sequence diagram showing an example of remote control of optical transceivers in an optical remote system according to an embodiment. Fig. 6 is a schematic diagram showing an example of downstream communication in the optical remote system according to an embodiment. Fig. 7 is a schematic diagram showing an example of upstream communication in the optical remote system according to an embodiment. Fig. 5 shows the remote control sequence of the optical transceiver 30_1 as a representative example, but the remote control sequences of the optical transceivers 30_2 and 30_3 are similar.

[0115] The management device 50 generates a control frame 1 for remotely controlling the optical transceiver 30_1. The control frame is, for example, an Ethernet frame, and more specifically, an Ethernet OAM frame. The control frame 1 stores control information for the optical transceiver 30_1.

[0116] As shown in Fig. 5, the management device 50 transmits control frame 1 using the Ethernet protocol (step S1). In Fig. 6, a circled "1" represents control frame 1. Note that Fig. 6 also shows control frames 2 and 3 for controlling the optical transceivers 30_2 and 30_3. A circled "2" represents control frame 2 for remotely controlling the optical transceiver 30_2, and a circled "3" represents control frame 3 for remotely controlling the optical transceiver 30_2. As shown in Fig. 6, each of control frames 1, 2, and 3 is transmitted through the transmission path 70_1 toward the optical wavelength division multiplexing SW 10_1.

[0117] The SW control unit 12 of the optical wavelength multiplexing SW 10_1 receives the control frame 1. The SW control unit 12 extracts the control information from the control frame 1 and outputs the extracted control information to the remote optical TRx control unit 13 (step S2). The remote optical TRx control unit 13 converts the input control information into commands to the optical transceiver 30 (step S3). The control information may be converted into multiple commands. In this example, it is assumed that the control information is converted into N commands (commands 1, 2, ..., N) (N is a natural number).

[0118] The remote optical TRx control unit 13 of the optical wavelength division multiplexing SW 10_1 outputs Command 1 to the OLT function unit 11_1 (step S4). The OLT function unit 11_1 generates an OAM frame containing Command 1 (GetRequest or SetRequest) (step S5). Specifically, the OLT function unit 11_1 generates OAM frame 1 addressed to the ONU function unit 31_1 of the optical transceiver 30_1.

[0119] The OLT function unit 11_1 transmits a downstream multiplexed control signal, which is an optical signal including the downstream control signal 1 carrying the OAM frame 1 (step S6). The optical transmitting / receiving unit 111 transmits the downstream multiplexed control signal as an optical signal of the above-mentioned control downstream wavelength. The downstream multiplexed control signal output from the optical transmitting / receiving unit 111 is transmitted to the optical transceiver 30_1 via the control signal multiplexing unit 16 and the optical wavelength division multiplexing coupler 20_1.

[0120] The C-TRx 311 of the optical transceiver 30_1 receives the downstream multiplexed control signal. The ONU function unit 31_1 extracts the OAM frame addressed to its own device from the downstream multiplexed control signal. The frame processing unit 313 extracts command 1 from the OAM frame (step S7) and outputs command 1 to the control unit 330, for example, as an electrical signal (step S8). The control unit 330 executes command 1 (step S9).

[0121] One of commands 1 to N is a command to set the transmission wavelength of the optical transmitter of U-TRx 301. The SetRequest command includes the address of a control register for setting the transmission wavelength of U-TRx 301 and the wavelength value (data). When a command to set the transmission wavelength of the optical transmitter of U-TRx 301 is given, the control unit 330 writes the specified value to the specified address of the control register. This sets (controls) the transmission wavelength of the optical transmitter of U-TRx 301.

[0122] The control unit 330 of the optical transceiver 30_1 acquires the execution result A of the command A and outputs the execution result 1 to the ONU function unit 31_1, for example, as an electrical signal (S10). The ONU function unit 31_1 generates an OAM frame A' containing the execution result A of the command 1 (step S11). The optical transceiver 30_1 burst-transmits an upstream control signal A (response signal) carrying the upstream OAM frame A' (step S12). Burst transmission is a process in which a transmission period during which a signal is transmitted is repeated with a non-transmission period during which no signal is transmitted, and an optical signal of the transmission wavelength is not output (no light is emitted) during the non-transmission period. Note that although the downstream control signal is not burst-transmitted here, the optical transceiver 111 may also burst-transmit the downstream control signal.

[0123] The upstream multiplexed control signal carrying the OAM frame A' reaches the OLT function unit 11_1 via the optical wavelength multiplexing coupler 20_1 and the control signal multiplexing unit 16 of the optical wavelength multiplexing SW 10_1.

[0124] The OLT function unit 11_1 of the optical wavelength division multiplexing SW 10_1 receives the upstream multiplexing control signal, extracts the OAM frame A' from the upstream multiplexing control signal, and obtains the execution result A from the OAM frame A' (step S13). The OLT function unit 11_1 outputs the execution result A by the optical transceiver 30_1 to the remote optical TRx control unit 13 (step S14).

[0125] The remote optical TRx control unit 13 outputs command B to the OLT function unit 11_1 in the same manner as in step S4 described above (step S15). The OLT function unit 11_1 transmits a downstream multiplexed control signal carrying an OAM frame containing command B in the same manner as in step S6 described above. Command B is executed in the ONU function unit 31_1, and an upstream control signal B on which execution result B of command B is superimposed is burst-transmitted from the optical transceiver 30_1. Thereafter, the operations of steps S4 to S14 are repeatedly executed for commands C...n. The OLT function unit 11_1 outputs the final execution result N to the remote optical TRx control unit 13 (step S16), and the remote optical TRx control unit 13 acquires execution results A, B,...,n.

[0126] The remote optical TRx control unit 13 generates response information in response to the control information sent to the optical transceiver 30_1 based on the execution results A, B, ..., n received from the optical transceiver 30_1. The remote optical TRx control unit 13 outputs the generated response information to the SW control unit 12 (step S17). The SW control unit 12 generates response frame A, which is an Ethernet OAM frame containing the input response information (step S18), and transmits the generated response frame A to the management device 50 (step S19).

[0127] The optical transceivers 30_2 and 30_3 can also be remotely controlled in the same way as the optical transceiver 30_1. In Figures 6 and 7, a square framed "A" indicates a downstream control signal A and an upstream control signal A, a square framed "B" indicates a downstream control signal B and an upstream control signal B, and a square framed "C" indicates a downstream control signal C and an upstream control signal C. The downstream multiplexed control signal is multiplexed with the downstream main signal and transmitted as a downstream optical multiplexed signal through the single-core transmission line 61_1.

[0128] The optical transceivers 30_2 and 30_3 also generate OAM frames B' and C' containing the execution results of the commands, similar to the optical transceiver 30_1. The optical transceivers 30_2 and 30_3 burst transmit the upstream control signals 2 and 3 carrying the OAM frames B' and C'.

[0129] For example, downstream control signals A, B, and C for the optical transceivers 30_1, 30_2, and 30_3 can be transmitted at different times, and upstream control signals A, B, and C output from the optical transceivers 30_1, 30_2, and 30_3 can be transmitted at different times. In another example, downstream control signals A, B, and C for two or three of the optical transceivers 30_1, 30_2, and 30_3 can be transmitted consecutively by time-division multiplexing (FIG. 6), and upstream control signals output from two or three of the optical transceivers 30_1, 30_2, and 30_3 can be transmitted consecutively by time-division multiplexing (FIG. 7).

[0130] 6. Modifications 6-1. First Modification FIG. 8 is a diagram showing a first modification of the optical remote control system according to the embodiment.

[0131] In the optical remote control system according to the first modification, an OLT 11A and a remote optical TRx control device 13A are provided in addition to an optical wavelength multiplexing SW 10A. That is, the OLT function unit 11 and the remote optical TRx control unit 13 are excluded from the optical wavelength multiplexing SW 10A. In this modification, the SW control unit 12A is not connected to the remote optical TRx control unit 13. Note that the other components of the optical wavelength multiplexing SW 10A (WSS 14, Add / Drop 15, and control signal multiplexing unit 16) are the same as those of the optical wavelength multiplexing SW 10 according to the embodiment.

[0132] The remote optical TRx control device 13A is connected to the management device 50 via a transmission path 70_1 based on known technology such as an electrical signal line, an optical signal line, or a wireless network. The remote optical TRx control device 13A includes a processor, an ASIC, an FPGA, etc., and has the same functions as the remote optical TRx control unit 13 according to the embodiment. In Fig. 8 , optical connections between multiple elements are indicated by solid lines, and connections between multiple elements that do not matter (optical connection, electrical connection, etc.) are indicated by dashed dotted lines. The management device 50 transmits control information to each of the optical wavelength multiplexing SW 10A and the remote optical TRx control device 13A.

[0133] The OLT 11A is connected to the remote optical TRx control device 13A via a transmission path based on known technology such as an electrical signal line, an optical signal line, or a wireless network. The OLT 11A includes a processor, an ASIC, an FPGA, etc., and has the same functions as the OLT function unit 11 according to the embodiment. The OLT 11A includes an optical transceiver unit 111A. The optical transceiver unit 111A is connected to the control signal multiplexing unit 16 of the optical wavelength multiplexing SW 10A via an optical transmission path.

[0134] 6-2. Second Modification FIG. 9 is a diagram showing a second modification of the optical remote control system according to the embodiment.

[0135] In the optical remote control system according to the second modification, an OLT 11 B is provided in addition to the optical wavelength multiplexing SW 10 A. The configuration of the optical wavelength multiplexing SW 10 A is the same as that of the optical wavelength multiplexing SW 10 A according to the first modification.

[0136] The OLT 11B includes a MAC control unit 112B, a remote optical TRx control unit 13B, and an optical transceiver unit 111B.

[0137] The remote optical TRx control unit 13B is connected to the management device 50 via a transmission path 70_1 using known technology such as an electrical signal line, an optical signal line, or a wireless network. The remote optical TRx control unit 13B is configured with a processor, an ASIC, an FPGA, etc., and has the same functions as the remote optical TRx control unit 13. In Fig. 9, optical connections between multiple elements are indicated by solid lines, and electrical connections between multiple elements are indicated by dashed lines.

[0138] The MAC control unit 112B is connected to the remote optical TRx control unit 13B. The MAC control unit 112B is configured with a processor, an ASIC, an FPGA, etc., and executes MAC control processing of the PON. The MAC control unit 112B has the same functions as the OLT function unit 11 according to the embodiment.

[0139] The optical transmitter / receiver 111B is connected to the control signal multiplexer 16 of the optical wavelength multiplexer SW 10A through an optical transmission line.

[0140] 6-3. Third Modification FIG. 10 is a diagram showing a third modification of the optical remote control system according to the embodiment.

[0141] In the optical remote control system according to the third modification, a remote optical TRx control device 13C is provided in addition to the optical wavelength multiplexing SW 10A. The configuration of the optical wavelength multiplexing SW 10A is the same as that of the optical wavelength multiplexing SW 10A according to the first modification.

[0142] The remote optical TRx control device 13C is connected to the management device 50 via a transmission path based on known technology such as an electrical signal line, an optical signal line, or a wireless network. The remote optical TRx control device 13C includes a processor, an ASIC, an FPGA, etc., and has the same functions as the remote optical TRx control unit 13 according to the embodiment. In Fig. 10 , optical connections between multiple elements are indicated by solid lines, and connections between multiple elements regardless of the connection form (optical connection, electrical connection, etc.) are indicated by dashed dotted lines.

[0143] A pluggable OLT 11C is attached to the remote optical TRx control device 13C. The pluggable OLT 11C is detachable from the remote optical TRx control device 13C.

[0144] The pluggable OLT 11C is electrically connected to the remote optical TRx control unit 13C. The pluggable OLT 11C includes a processor, an ASIC, an FPGA, etc., and has the same functions as the OLT function unit 11 according to the embodiment. The pluggable OLT 11C includes an optical transceiver unit 111C. The optical transceiver unit 111C is connected to the control signal multiplexing unit 16 of the optical wavelength multiplexing SW 10A via an optical transmission path.

[0145] 6-4. Fourth Modification FIG. 11 is a diagram showing a fourth modification of the optical remote control system according to the embodiment.

[0146] In the optical remote control system according to the fourth modification, an optical wavelength multiplexing SW 10D includes a plurality of OLT function units 11D1, 11D2, and 11D3.

[0147] The SW control unit 12 is connected to the management device 50 via a transmission path based on known technology, such as an electrical signal line, an optical signal line, or a wireless network. The SW control unit 12 is connected to a remote optical TRx control unit 13D. The remote optical TRx control unit 13D includes a processor, an ASIC, an FPGA, etc. In addition to functions similar to those of the remote optical TRx control device 13A according to the embodiment, the remote optical TRx control unit 13D has a function of outputting commands from the management device 50 to a specific one or more OLT function units 11D1, 11D2, and 11D3. In FIG. 11 , optical connections between multiple elements are indicated by solid lines, electrical connections between multiple elements are indicated by dashed lines, and connections between multiple elements regardless of the connection form (optical connection, electrical connection, etc.) are indicated by dashed lines.

[0148] Each of the OLT functional units 11D1, 11D2, and 11D3 is configured by, for example, a processor, an ASIC, an FPGA, etc., and includes an optical transceiver unit 111D1, 111D2, and 111D3. Each of the OLT functional units 11D1, 11D2, and 11D3 may be a pluggable OLT that can be attached to and detached from the optical wavelength multiplexing SW 10D.

[0149] Each of the OLT function units 11D1, 11D2, and 11D3 is connected to the remote optical TRx control unit 13D. Each of the OLT function units 11D1, 11D2, and 11D3 has the same function as the OLT function unit 11 according to the embodiment.

[0150] The optical transmitters and receivers 111D1, 111D2, and 111D3 are connected to the control signal multiplexer 16D via optical transmission paths. The other configurations of the optical wavelength multiplexer SW 10D are the same as those of the optical wavelength multiplexer SW 10 according to the embodiment.

[0151] For example, the optical transceivers 30 under the optical wavelength multiplexing SW 10D can be divided into three systems, and one OLT function unit can be assigned to each system of the optical transceivers 30. This allows the load of remote control processing to be distributed by the OLT function units 11D1, 11D2, and 11D3 when a large number of optical transceivers 30 are connected to the optical wavelength multiplexing SW 10D.

[0152] 6-5. Fifth Modification FIG. 12 is a block diagram showing the circuit configuration of a frame processing unit in a fifth modification of the optical transceiver according to the embodiment.

[0153] The frame processing unit 313 includes a SerDes 351, an 8B / 10B decoder 352, a MAC receiving unit 353, a distribution unit 354, an MPCP processing unit 355, a DBA 356, a merging unit 357, a MAC transmitting unit 358, an 8B / 10B encoder 359, a control frame receiving buffer 361, a control frame transmitting buffer 362, and a processor interface 363.

[0154] The SerDes (Serializer Deserializer) 351 is a circuit that converts parallel signals to serial signals and vice versa. A serial signal is output from the LA to the SerDes 351, and the SerDes 351 converts the input serial signal into a code-synchronized parallel signal. The SerDes 351 outputs the parallel signal to an 8B / 10B decoder 352.

[0155] The parallel data output from the SerDes 351 is 8-bit data encoded into 10-bit data. The 8B / 10B decoder 352 is a circuit that decodes (inversely converts) the 10-bit parallel data input from the SerDes 351 into 8-bit parallel data.

[0156] The MAC (Media Access Control) receiver 353 is a circuit that acquires Ethernet frames from the data output from the 8B / 10B decoder 352. The MAC receiver 353 performs, for example, error detection and decryption processing of encrypted frames. The MAC receiver 353 outputs the acquired frames to the sorter 354.

[0157] The frames acquired by the MAC receiving unit 353 may include three types of frames: control frames, MPCP frames, and user frames. MPCP (Multi Point Control Protocol) frames are frames used for registering ONUs in the OLT and for dynamic bandwidth allocation (DBA) in the OLT. User frames are frames other than control frames and MPCP frames. An example of a control frame is the above-mentioned OAM frame. However, the control frame is not limited to an OAM frame as long as it stores control information including a request or a response.

[0158] The sorting unit 354 is a circuit that identifies the type of frame (control frame, MPCP frame, or user frame) input from the MAC receiving unit 353 and sorts the frame according to the identified type. Specifically, if the frame input from the MAC receiving unit 353 is a control frame, the sorting unit 354 outputs the control frame to the control frame receiving buffer 361. If the frame input from the MAC receiving unit 353 is an MPCP frame, the sorting unit 354 outputs the MPCP frame to the MPCP processing unit 355. In other words, the sorting unit 354 acquires the control frame input from the MAC receiving unit 353 and outputs the acquired control frame to the control frame receiving buffer 361. The sorting unit 354 acquires the MPCP frame input from the MAC receiving unit 353 and outputs the acquired MPCP frame to the MPCP processing unit 355.

[0159] The frame processing unit 313 does not have a buffer (a receiving buffer and a transmitting buffer) for user frames. If the frame input from the MAC receiving unit 353 is a user frame, the allocating unit 354 discards the user frame.

[0160] The control frame receive buffer 361 is a buffer that temporarily stores received control frames. The processor interface 363 is connected to the control frame receive buffer 361, the control frame transmit buffer 362, and the processor 314. The processor interface 363 is a circuit for inputting and outputting data to and from the processor 314.

[0161] The processor interface 363 reads the control frame from the control frame receive buffer 361 and outputs the read control frame to the processor 314. The processor 314 processes the input control frame. For example, the processor 314 acquires control information from the input control frame. The processor 314 outputs the acquired control information to the processor 321.

[0162] The processor 321 executes commands based on the control information and outputs the command execution results to the processor 314. The processor 314 generates a control frame that stores the input command execution results and outputs the generated control frame to the processor interface 363. The control frame transmission buffer 362 is a buffer that temporarily stores control frames to be transmitted. The processor interface 363 writes the input control frames to the control frame transmission buffer 362.

[0163] The MPCP processing unit 355 is a circuit that generates and processes MPCP frames together with the DBA 356. The MPCP processing unit 355 performs time synchronization based on the input MPCP frame, processes MPCP frames related to ONU registration, and outputs MPCP frames related to DBA to the DBA 356. Specifically, the MPCP frames related to DBA include a REPORT frame and a GATE frame. The OLT function unit 11 assigns an upstream bandwidth to each optical transceiver 30 and transmits a GATE frame that stores the assigned upstream bandwidth value. The upstream bandwidth value includes the upstream transmission start time and the amount of data to be transmitted. The DBA 356 is a circuit that performs processing corresponding to the DBA of the OLT function unit 11, obtains the upstream bandwidth value from the GATE frame, and sets the assigned upstream bandwidth. Specifically, the DBA 356 sets the input upstream transmission start time and transmission data amount, and schedules the transmission of frames stored in the control frame transmission buffer 362. Furthermore, the DBA 356 acquires the upstream data amount accumulated in the control frame transmission buffer 362. The DBA 356 generates a REPORT frame that describes the input upstream data amount, and outputs the generated REPORT frame to the MPCP processing unit 355. The MPCP processing unit 355 assigns a timestamp to the input REPORT frame, and outputs it to the merging unit 357.

[0164] The junction unit 357 is a circuit that accepts input of multiple types of frames and outputs the accepted frames in sequence. Specifically, the junction unit 357 reads control frames from the control frame transmission buffer 362 and accepts MPCP frames output from the MPCP processing unit 355. The junction unit 357 outputs the input control frames and MPCP frames in sequence to the MAC transmission unit 358.

[0165] For example, no user frames are input to the merging unit 357. Therefore, the process of merging user frames with control frames and MPCP frames is omitted in the merging unit 357. Note that user frames may also be input to the merging unit 357. In this case, the merging unit 357 sequentially outputs the input control frames, MPCP frames, and user frames to the MAC transmitting unit 358.

[0166] The MAC transmission unit 358 is a circuit for transmitting input control frames and MPCP frames. For example, the MAC transmission unit 358 performs encryption processing on the frames and adds error detection information to the frames.

[0167] The MAC transmission unit 358 divides the frame into 8-bit data and outputs the data to the 8B / 10B encoder 359. The 8B / 10B encoder 359 is a circuit that encodes the input 8-bit data into 10-bit data. The 8B / 10B encoder 359 outputs the 10-bit parallel data to the SerDes 351.

[0168] The SerDes 351 converts the input 10-bit parallel data into serial data, and outputs the serial data to the LDD.

[0169] The frame processing unit 313 discards received user frames and does not generate user frames for transmission. Therefore, the frame processing unit 313 does not have a receive buffer or a transmit buffer for user frames. Furthermore, the ONU function unit 31 does not need a UNI (User Network Interface) for inputting and outputting user frames to and from the user device 40. This reduces the processing load on the ONU function unit 31 and reduces power consumption.

[0170] The transmission rate of the control frames is limited. In a specific example, the transmission rate of the control frames is 10 frames per second (10 frames / second) or less. Therefore, the processor 314 may sleep and wake up at a period set in accordance with the timing of transmitting and receiving the control frames. For example, the wake-up period is 0.1 seconds.

[0171] During a wake-up period, the processor 314 reads a control frame buffered in the control frame receive buffer 361 via the processor interface 363. During the wake-up period, the processor 314 obtains control information from the read control frame and executes the command (request) included in the control information. The processor 314 generates a control frame that stores a response that is the result of executing the command, and writes the generated control frame to the control frame transmit buffer 362 via the processor interface 363. After writing the control frame to the control frame transmit buffer 362, the processor 314 goes to sleep again.

[0172] At least a part of the frame processing unit 313 may be settable to either a normal mode in which normal operation is performed or a power-down mode in which operation is stopped. The power-down mode is an operation mode in which the frame processing unit 313, which is an FPGA, stops operating while retaining configuration information (configuration data) of the FPGA.

[0173] For example, the processor 314 wakes up the frame processing unit 313 from the power-down mode and starts it up. This cancels the power-down state of the frame processing unit 313, causing the frame processing unit 313 to transition to normal mode. After reading and writing the control frame as described above to the frame processing unit 313 in normal mode, the processor 314 powers down the frame processing unit 313 before the processor 314 goes to sleep. The processor 314 goes to sleep after the frame processing unit 313 has powered down. This enables further power savings in the optical transceiver 30.

[0174] FIG. 13 is a flowchart illustrating the operation of the processor in the fifth modification of the optical transceiver according to the embodiment.

[0175] The processor 314 repeatedly sleeps and wakes up in a set cycle. One set cycle includes a wake-up period and a sleep period. The start of the sleep period (i.e., the end of the wake-up period) is set as the sleep time, and the end of the sleep period (i.e., the start of the wake-up period) is set as the wake-up time.

[0176] The sleeping processor 314 maintains the sleep state until the wake-up time arrives (NO in step S101). When the wake-up time arrives (YES in step S101), the processor 314 wakes up (step S102).

[0177] The processor 314 activates the frame processing unit 313 (step S103), which causes the frame processing unit 313 to transition from the power down mode to the normal mode.

[0178] In the frame processing unit 313 in normal mode, the control frame is buffered in the control frame receiving buffer 361. The processor 314 reads the control frame from the control frame receiving buffer 361 (step S104).

[0179] The processor 314 obtains control information from the read control frame and executes the command (step S105). The processor 314 generates a control frame including the execution result of the command and writes the generated control frame to the control frame transmission buffer 362 (step S106). The frame processing unit 313 outputs the control frame buffered in the control frame transmission buffer 361 to the LDD.

[0180] The processor 314 powers down the frame processing unit 313 (step S107), causing the frame processing unit 313 to transition from the normal mode to the power-down mode.

[0181] The processor 314 remains awake until the sleep time arrives (NO in step S108). When the sleep time arrives (YES in step S108), the processor 314 sets the wake-up time and goes to sleep (step S109), and then returns to step S101.

[0182] The OLT function unit 11 and the processor 314 share a predetermined set period and are synchronized based on, for example, the MPCP time. The OLT function unit 11 transmits control frames and GATE frames so that the frame processing unit 314 can receive these frames during the normal mode period, and allocates an upstream bandwidth to the optical transceiver 30 so that the frame processing unit 314 can transmit control frames and REPORT frames during the normal mode period.

[0183] [6-6. Other Modifications] In the above embodiment, the optical transceiver 30 is remotely controlled using an EPON (Ethernet PON) defined in IEEE 802.3ah, but this is not limiting. For example, a GPON (Gigabit PON) defined in ITU-T G.984 may be used. In this case, an OMCI (ONU Management and Control Interface) frame is used instead of an OAM frame. Furthermore, the optical transceiver 30 may be remotely controlled using a frame defined by the user.

[0184] [7. Supplementary Note] The embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is defined by the claims, not the above-described embodiments, and includes meanings equivalent to the claims and all modifications within the scope thereof.

[0185] 1 Optical communication system 2, 2_1, 2_2, 2_3 Optical remote control system 3 Optical communication network 3A Metro network 3B Access network 10, 10_1, 10_2, 10_3, 10A, 10D Optical wavelength multiplexing switch (optical wavelength multiplexing SW) 11, 11_1, 11_2, 11_3, 11D1, 11D2, 11D3 OLT function unit 11A, 11B OLT 11C Pluggable OLT 111, 111A, 111B, 111C, 111D1, 111D2, 111D3 Optical transmitting and receiving unit 112B MAC control unit 12, 12A SW control unit 13, 13B, 13D Remote optical transceiver control unit (remote optical TRx control unit) 13A, 13C Remote optical transceiver control device (remote optical TRx control device) 14 Wavelength selective switch (WSS) 15 Wavelength multiplexing / demultiplexing unit (Add / Drop) 16, 16D Control signal multiplexing unit 16A_1, 16B_1, 16A_2, 16B_2, 16A_3, 16B_3, 17_1, 17_2, 17_3 WDM coupler 20, 20_1, 20_2, 20_3 Optical wavelength multiplexing coupler 21, 21A, 22A, 22B, 24A_1, 24A_2, 24A_3, 24B_1, 24B_2, 24B_3, 304A, 304B, 304C WDM coupler 23A, 23B Optical coupler 30, 30_1, 30_2, 30_3, 30_4, 30_5, 30_6, 30_7, 30_8, 30_9 Optical transceiver 301 Optical transmitter / receiver unit (U-TRx) 302 Driver circuit 303 Digital signal processor (DSP) 311 Optical transmitter / receiver unit (C-TRx) 31, 31_1, 31_2, 31_3, 31_4, 31_5, 31_6, 31_7, 31_8,31_9 ONU function unit 312 LDD / LA 313 Frame processing unit (acquisition unit) 314 Processor 315 Memory 32 Microcontroller unit (MCU) 321 Processor 322 Memory 323 D / A converter (DAC) 324 A / D converter (ADC) 330 Control unit 351 SerDes 352 8B / 10B decoder 353 MAC receiving unit 354 Distribution unit 355 MPCP processing unit 356 DBA 357 Merging unit 358 MAC transmitting unit 359 8B / 10B encoder 361 Control frame receiving buffer 362 Control frame transmitting buffer 363 Processor interface 40, 40_1, 40_2, 40_3, 40_4, 40_5, 40_6, 40_7, 40_8, 40_9 User device 50 Management device 60_1, 60_2, 60_3 Optical transmission path (two-core transmission path) 61_1, 61_2, 61_3, 62_1, 62_2, 62_3 Optical transmission path 61A_1, 61A_2, 61A_3 Downstream transmission path 61B_1, 61B_2, 61B_3 Upstream transmission path 70_1, 70_2, 70_3 Transmission path MP_1, MP_2 Metro side port AP_1, AP_2, AP_3 Access side port PA, PB Port,

Claims

1. An optical remote control system comprising: a plurality of optical transceivers connected to an optical communications network that transmits optical signals in which a plurality of main signals are wavelength division multiplexed; and a remote control device connected to the optical communications network, wherein the remote control device includes a control optical transceiver that transmits a plurality of control signals of a single wavelength, and each of the plurality of optical transceivers includes: a first optical transceiver that transmits and receives the main signals; a second optical transceiver that receives the control signals separated from an optical multiplexed signal in which the main signals and the control signals are wavelength division multiplexed; and a control unit that controls the first optical transceiver based on the control signals received by the second optical transceiver, wherein the second optical transceiver transmits a single wavelength response signal in response to the control signal as a burst optical signal.

2. The optical remote control system according to claim 1, wherein the remote control device functions as an optical line terminal on the central office side in a passive optical network, includes the control optical transceiver unit, and includes an OLT function unit that transmits the plurality of control signals as time division multiplexed optical signals, and the optical transceiver functions as an optical line terminal on the subscriber side in a passive optical network, and includes an ONU function unit connected to the second optical transceiver unit that receives the control signals that are time division multiplexed optical signals.

3. An optical remote control system according to claim 1 or claim 2, further comprising an optical wavelength division multiplexing coupler arranged between said remote control device and said plurality of optical transceivers in said optical communication network, said optical wavelength division multiplexing coupler separating said plurality of main signals from said optical signal by wavelength, and distributing said optical multiplexed signal, in which said separated main signals and said control signals are wavelength division multiplexed, to each of said plurality of optical transceivers.

4. An optical transceiver comprising: a first optical transceiver for transmitting and receiving a main signal; a second optical transceiver for receiving a control signal of a single wavelength separated from an optical multiplexed signal in which the main signal and control signal are wavelength division multiplexed; and a control unit for controlling the first optical transceiver based on the control signal received by the second optical transceiver; wherein the control signal is transmitted from a remote control device, the second optical transceiver receives the transmitted control signal, and the second optical transceiver transmits a response signal of a single wavelength to the control signal as a burst optical signal.

5. The optical transceiver of claim 4, wherein the control signal is time-division multiplexed with a second control signal for controlling a third optical transceiver provided in a second optical transceiver different from the optical transceiver, the optical multiplexed signal is a multiplexed control signal in which the control signal and the second control signal are time-division multiplexed, and a signal in which the main signal and a second main signal received by the third optical transceiver are wavelength-division multiplexed, the second optical transceiver converts the multiplexed control signal, which is a received optical signal, into an electrical signal, and the optical transceiver further comprises an acquisition unit that acquires an electrical signal corresponding to the control signal from the electrical signal into which the multiplexed control signal is converted.

6. The optical transceiver according to claim 5, wherein the optical transceiver functions as an optical line terminal in a passive optical network and includes an ONU function unit connected to the second optical transceiver unit that receives the multiplexed control signal, and the ONU function unit includes the acquisition unit.

7. The optical transceiver according to any one of claims 4 to 6, wherein the control signal includes a control frame used in a passive optical network.

8. The optical transceiver according to claim 7, wherein the ONU function unit discards user frames, which are frames different from MPCP frames and the control frames, among received frames.

9. The optical transceiver according to claim 7, wherein the ONU function unit does not include a receiving buffer for storing user frames, which are frames different from MPCP frames and the control frames, among received frames.

10. An optical transceiver according to any one of claims 7 to 9, wherein the ONU function unit does not include a transmission buffer for storing user frames, which are frames different from MPCP frames and the control frames, among transmission frames.

11. The optical transceiver of claim 7, wherein the ONU functional unit includes a frame processing unit and a processor, the frame processing unit outputs the received control frame to the processor and transmits the control frame input from the processor, the processor processes a request contained in a request frame, which is the control frame input from the frame processing unit, and generates a response frame, which is the control frame containing a response to the request, and outputs it to the frame processing unit, and the processor goes to sleep after outputting the response frame.

12. The optical transceiver according to claim 11, wherein the frame processing unit is capable of being powered down, and the processor powers down the frame processing unit during a power-down period that is based on a sleep period for the processor to sleep.

13. A remote control device connected to an optical communication network that transmits optical signals in which multiple main signals are wavelength-division multiplexed, comprising: an OLT function unit that functions as an optical line terminal on the central office side in a passive optical network and generates control signals to control first optical transceivers provided in multiple optical transceivers connected to the optical communication network; and a control optical transceiver unit that transmits a control signal of a single wavelength so that a second optical transceiver unit in the optical transceiver including an ONU function unit that functions as an optical line terminal on the subscriber side in the passive optical network can receive the control signal; wherein the control optical transceiver unit receives a response signal of a single wavelength in response to the control signal, and the response signal is a signal transmitted as a burst optical signal from the second optical transceiver unit.

14. An optical wavelength division multiplexing coupler arranged between a remote control device and a plurality of optical transceivers in an optical communication network that transmits optical signals in which a plurality of main signals are wavelength division multiplexed, comprising: a first port that receives a wavelength division multiplexed signal of the plurality of main signals and control signals transmitted from the remote control device for controlling first optical transmitters and receivers provided in the plurality of optical transceivers; a WDM coupler that separates the plurality of main signals included in the wavelength division multiplexed signal received by the first port, by wavelength; and a second port that transmits to each of the plurality of optical transceivers an optical multiplexed signal in which each of the plurality of main signals separated by the WDM coupler and the control signal are wavelength division multiplexed.

15. An optical remote control method comprising the steps of: transmitting a control signal of a single wavelength from a remote control device; transmitting an optical multiplexed signal in which a main signal and the control signal are wavelength division multiplexed over an optical communication network; receiving the main signal separated from the optical multiplexed signal by a first optical transceiver; receiving the control signal of a single wavelength different from the wavelength of the main signal separated from the optical multiplexed signal by a second optical transceiver; controlling the first optical transceiver based on the control signal received by the second optical transceiver; and transmitting a single wavelength response signal to the control signal as a burst optical signal by the second optical transceiver.

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