Communication device, communication method, and communication system

Abstract

To properly perform quantum key distribution via optical wavelength division multiplexing links. [Solution] A communication device is provided that communicates an optical signal based on an electrical signal in which a first control signal from a first optical communication device to a second optical communication device and a control signal for receiving signal processing from a first quantum key distribution device to a second quantum key distribution device are multiplexed.

Description

Technical Field

[0006] , ,

[0007] , ,

[0001] The present disclosure relates to a communication device, a communication method, and a communication system.

Background Art

[0002] There is known QKD over WDM, which is a technique for performing quantum key distribution (QKD) via an optical wavelength division multiplexing (WDM) link (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the technique described in Patent Document 1, for example, quantum key distribution may not be appropriately performed via an optical wavelength division multiplexing link.

[0005] An object of the present disclosure is to provide a technique capable of appropriately performing quantum key distribution via an optical wavelength division multiplexing link in view of the above problems.

Means for Solving the Problems

[0006] In a first aspect according to the present disclosure, there is provided a communication device that communicates an optical signal based on an electrical signal in which a first control signal from a first optical communication device to a second optical communication device and a control signal for receiving signal processing from a first quantum key distribution device to a second quantum key distribution device are multiplexed.

[0007] Furthermore, a second aspect of the present disclosure provides a communication method for communicating an optical signal based on an electrical signal in which a first control signal from a first optical communication device to a second optical communication device and a control signal for receiving signal processing from a first quantum key distribution device to a second quantum key distribution device are multiplexed.

[0008] Furthermore, a third aspect of the present disclosure provides a communication system comprising a first communication device having a first optical communication device and the first quantum key distribution device, and a second communication device having a second optical communication device and the second quantum key distribution device, wherein the first communication device multiplexes a first control signal from the first optical communication device to the second optical communication device and a control signal for receiving signals from the first quantum key distribution device to the second quantum key distribution device, and transmits an optical signal based on the multiplexed electrical signal from the first optical communication device to the second optical communication device. [Effects of the Invention]

[0009] From one perspective, quantum key distribution can be appropriately performed via optical wavelength division multiplexing links. [Brief explanation of the drawing]

[0010] [Figure 1] This is a diagram showing an example of the configuration of a communication system according to the embodiment. [Figure 2] This figure shows an example of the configuration of a communication device according to the embodiment. [Figure 3] This is a flowchart showing an example of processing by a communication device according to an embodiment. [Figure 4] This figure shows an example of the hardware configuration of the information processing device according to the embodiment. [Modes for carrying out the invention]

[0011] The principles of this disclosure will be described with reference to several exemplary embodiments. These embodiments are described for illustrative purposes only and should be understood as helping those skilled in the art to understand and implement this disclosure without implying any limitation on the scope of this disclosure. The disclosures described herein may be implemented in various ways other than those described below.

[0012] In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which this disclosure belongs.

[0013] Embodiments of the present disclosure will be described below with reference to the drawings. Each drawing is merely illustrative for illustrating one or more embodiments. Each drawing may be associated not only with one specific embodiment but also with one or more other embodiments. As those skilled in the art will understand, various features or steps described with reference to any one drawing can be combined with features or steps shown in one or more other drawings, for example, to create embodiments not explicitly shown or described. Not all features or steps shown in any one drawing to illustrate an exemplary embodiment are necessarily required, and some features or steps may be omitted. The order of steps described in any of the drawings may be changed as appropriate.

[0014] <System Configuration> Referring to Figure 1, the configuration of the communication system 1 according to the embodiment will be described. Figure 1 is a diagram showing an example of the configuration of the communication system 1 according to the embodiment. In the example of Figure 1, the communication system 1 has a communication device 10A (an example of the "first communication device"), a communication device 10B (an example of the "second communication device"), a communication device 10C, a communication device 10D (hereinafter, when it is not necessary to distinguish between communication devices 10A to D, they will simply be referred to as "communication device 10"), and a server 30. Note that the number of each communication device 10 and the server 30 is not limited to the example in Figure 1.

[0015] In the example shown in Figure 1, each communication device 10 and the server 30 are connected to each other via a monitoring and control network N. Examples of the network N include, for example, the Internet, mobile communication systems, wireless LAN (Local Area Network), LAN, and buses. Examples of mobile communication systems include, for example, fifth-generation mobile communication systems (5G), fourth-generation mobile communication systems (4G), third-generation mobile communication systems (3G), etc.

[0016] Furthermore, each communication device 10 is connected to enable communication via optical communication networks F1 to F3, such as optical fibers. Each communication device 10 forms a data communication network, such as a backbone network. In the example in Figure 1, communication device 10D is connected to communication device 10A, communication device 10A is connected to communication devices 10B and 10D, and communication device 10B is connected to communication devices 10A and 10C.

[0017] <Configuration of communication device 10> Next, with reference to Figure 2, the configuration of the communication device 10 according to the embodiment will be described. Figure 2 is a diagram showing an example of the configuration of the communication device 10 according to the embodiment. In the example in Figure 2, communication device 10A and communication device 10B are connected by an optical fiber. The configuration of communication device 10B is the same as that of communication device 10A.

[0018] The communication device 10A includes an optical communication device 11A and a quantum key distribution device 12A. Furthermore, a transmitting optical fiber FSA and a receiving optical fiber FRA are connected to the communication device 10A.

[0019] The optical communication device 11A includes a transmission amplifier (AMP, amplifier) 111A, a reception amplifier 112A, an OSC processing unit 113A, a transfer unit 114A, and an OSC transmission / reception unit 115A. The transmission amplifier 111A is an amplifier that amplifies an optical signal transmitted by the optical communication device 11A to another communication device 10B at a wavelength (first wavelength) for data transmission via the transmission optical fiber FSA. The transmission amplifier 111A transmits the optical signal 201 (upward WDM optical signal, optical signal for data communication) obtained by amplifying an optical signal from another communication device (for example, the communication device 10D) to another communication device 10B via the transmission optical fiber FSA.

[0020] The reception amplifier 112A is an amplifier that amplifies an optical signal received by the optical communication device 11A from another communication device 10B at a wavelength (fourth wavelength) for data reception via the reception optical fiber FRA. The reception amplifier 112A amplifies the optical signal 211 (downward WDM optical signal) received from another communication device 10B via the reception optical fiber FRA and transmits it to another communication device (for example, the communication device 10D).

[0021] The OSC processing unit 113A processes information regarding an optical signal for data communication, for example, by an OSC (Optical Supervisory Channel). The OSC processing unit 113A transmits and receives packets (for example, IP packets or Ethernet frames) as electrical signals to and from the OSC transceiver unit 115A via the transfer unit 114A. The electrical signal may include a control signal (first control signal) of the OSC. In this case, the first control signal may include a control signal for loopback control of the transmission amplifier 111A that amplifies the optical signal transmitted by the optical communication device 11A and the reception amplifier 112B that amplifies the optical signal for data communication received by the optical communication device 11B. Thereby, for example, based on the quality of the optical signal amplified by the reception amplifier 112B, the output power etc. from the transmission amplifier 111A can be adjusted. Note that the OSC is a channel for remote monitoring control of an optical transmission device (for example, a relay optical amplifier, an optical node), and its functions are defined in ITU-T G.692 / G.807. The OSC is transmitted and received for each interval between relay optical amplifiers (OTS (Optical Transmission Section) interval).

[0022] The transfer unit 114A transfers (transmits) the packet to the OSC processing unit 113A or the key distillation processing unit 121A, for example, based on information indicating the destination of the packet received from the OSC transceiver unit 115A. Further, the transfer unit 114A multiplexes the packet received from the OSC processing unit 113A and the packet which is an electrical signal received from the key distillation processing unit 121A and transfers it to the OSC transceiver unit 115A. The transfer unit 114A may be realized by, for example, a layer 2 switch.

[0023] The OSC transceiver unit (Tx / Rx) 115A converts the electrical signal received from the transfer unit 114A into an optical signal and transmits it as an optical signal 202 of a wavelength for OSC transmission (second wavelength) to another communication device 10B using the transmission optical fiber FSA. Further, the OSC transceiver unit 115A converts the optical signal 212 received from another communication device 10B at a wavelength for OSC reception (fifth wavelength) into a packet (frame) of an electrical signal using the reception optical fiber FRA and outputs it to the transfer unit 114A.

[0024] The quantum key distribution device 12A includes a key distillation processing unit 121A and a QKD communicator 122A. The QKD communicator 122A is a transmitter or receiver that transmits or receives an optical signal (quantum optical signal) for quantum key distribution, which uses the principles of quantum mechanics to detect eavesdropping when distributing key data, using an optical signal 203 (quantum optical signal) of a wavelength (third wavelength) for QKD transmission. The QKD communicator 122A, which is the transmitter, may transmit key data to the receiver by, for example, the BB84 method, which transmits 1 bit of key information per photon, or the CV-QKD method, which transmits 1 bit of key information on the phase difference between a weak light wave and normal light.

[0025] The key distillation processing unit 121A performs key distillation processing in quantum key distribution to share a secure cryptographic key by eliminating bits that may be intercepted. The key distillation processing unit 121A transmits and receives electrical signals of packets (e.g., IP packets or Ethernet frames) with the OSC transceiver unit 115A via the transfer unit 114A. The key distillation processing unit 121A transmits, for example, a control signal for QKD (second control signal) to be sent to another communication device 10B and a control signal for processing the received signal of the quantum channel (fifth control signal) to the OSC transceiver unit 115A via the transfer unit 114A.

[0026] Furthermore, the key distillation processing unit 121A receives, for example, a control signal for QKD (fourth control signal) received from another communication device 10B via the transfer unit 114A from the OSC transceiver unit 115A. The control signal for QKD may include key distillation data. The key distillation data may include, for example, information necessary for performing base verification, error correction, and security enhancement, which is communicated bidirectionally between the transmitter and receiver.

[0027] The control signals for processing the received signals of the quantum channel may include, for example, at least one of the following: a clock signal, a bit position synchronization signal, and a bit error rate (BER) estimation signal. The clock signal may be the clock signal used as a reference by the transmitter. If clock synchronization is required between the transmitter and receiver during key distillation, the clock signal used as a reference by the transmitter may be transmitted to the receiver.

[0028] The bit position synchronization signal may be, for example, a signal used to accurately extract bits at the receiver from a signal transmitted by the transmitter. The bit position synchronization signal may also be, for example, a specific flag pattern appended to the beginning and end of the data. The bit error rate estimation signal may also be, for example, a specific pattern of data shared in advance between the transmitter and receiver to estimate the bit error rate.

[0029] Communication device 10B includes an optical communication device 11B and a quantum key distribution device 12B. Furthermore, a transmitting optical fiber FSB and a receiving optical fiber FRB are connected to communication device 10. The configuration of communication device 10B is the same as that of communication device 10A.

[0030] <Processing> Next, with reference to Figure 3, an example of the processing of the communication device 10 according to the embodiment will be described. Figure 3 is a flowchart of an example of the processing of the communication device 10 according to the embodiment. Note that the order of processing described below is an example for illustrative purposes and may be executed in any order as long as it is not contradictory. In the following, an example will be described in which the QKD communication device 122A of the communication device 10A is the transmitter and the QKD communication device 122B of the communication device 10A is the receiver.

[0031] In step S101, the optical communication device 11A transmits an optical signal 201 (uplink WDM optical signal) to the other optical communication device 11B at the wavelength for data transmission (first wavelength) using the transmitting amplifier 111A and the transmitting optical fiber FSA. As a result, relatively large-sized communication data is transmitted from the communication device 10A to the communication device 10B.

[0032] Next, the optical communication device 11A receives an optical signal 211 (downlink WDM optical signal) from another optical communication device 11B at a wavelength for data reception (fourth wavelength) using the receiving amplifier 112A and the receiving optical fiber FRA (step S102). As a result, relatively large communication data is transmitted from the communication device 10B to the communication device 10A.

[0033] Next, the QKD communicator 122A transmits the optical signal 203 (quantum optical signal) for quantum key distribution to the QKD communicator 122B using the transmitting optical fiber FSA at the wavelength for QKD transmission (third wavelength) (step S103).

[0034] Next, the OSC transceiver 115A converts the electrical signal received from the transfer unit 114A into an optical signal and transmits it to another optical communication device 11B using the transmitting optical fiber FSA as an optical signal 202 (upstream OSC optical signal) at the wavelength for OSC transmission (second wavelength) (step S104). Here, the transfer unit 114A may output the electrical signals of each packet, which are multiplexed from the first control signal packet received from the OSC processing unit 113A and the second and fifth control signal packets received from the key distillation processing unit 121A, to the OSC transceiver 115A. Then, the OSC transceiver 115A converts the electrical signals of each multiplexed packet received from the transfer unit 114A into an optical signal and transmits it.

[0035] (Example of prioritizing the OSC control signal (first control signal) for multiplexing) The transfer unit 114A may multiplex the first control signal with priority over the control signal for receiving signal processing (the fifth control signal). This reduces, for example, the delay and jitter (fluctuation) caused by multiplexing to the OSC control signal. As a result, the degradation of data transmission quality by optical communication can be reduced.

[0036] In this case, the forwarding unit 114A may reserve a specific bandwidth for packets (frames) whose source MAC address or IP address belongs to the OSC processing unit 113A. When the forwarding unit 114A receives such a packet, it may forward the packet via a first queue for transmitting data within that specific bandwidth.

[0037] Furthermore, the forwarding unit 114A may, for example, forward packets whose source MAC address or IP address is not that of the OSC processing unit 113A via a second queue, which is used to forward data when the first queue is empty.

[0038] (An example of determining the priority of multiplexing control signals (5th control signal) for receiving signal processing based on the data size of the stored quantum keys.) The transfer unit 114A may determine the priority of multiplexing control signals for receiving signal processing based on the data size of the stored quantum keys. This allows, for example, the transmission of the fifth control signal to be prioritized according to the data size of the quantum key (final key) delivered from the transmitter to the receiver and stored. In this case, the transfer unit 114A may determine a higher priority for multiplexing control signals for receiving signal processing, for example, the larger the data size of the stored quantum keys. This reduces the situation in which, for example, there is a delay (waiting time) in the decoding process of data transmitted by optical communication due to the lack of remaining quantum keys.

[0039] In this case, the transfer unit 114A may, for example, multiplex the fifth control signal with first priority if the data size of the stored quantum key is greater than or equal to a threshold. Alternatively, the transfer unit 114A may, for example, multiplex the fifth control signal with second priority, which is higher than first priority, if the data size of the stored quantum key is not greater than or equal to the threshold. The first priority may be lower than the priority of at least one of the first and second control signals. The second priority may be the same as the priority of at least one of the first and second control signals. In this case, the transfer unit 114A may, for example, statistically multiplex the fifth control signal with at least one of the first and second control signals. The second priority may also be higher than the priority of at least one of the first and second control signals. In this case, the transfer unit 114A may, for example, reserve a specific bandwidth for the fifth control signal. The transfer unit 114A may receive information indicating the data size of the stored quantum key, or instructions for priority control according to the data size of the stored quantum key, from the key distillation processing unit 121A.

[0040] (An example of prioritizing the control signal for receiving signal processing over the key distillation data for multiplexing.) The transfer unit 114A may multiplex the control signal for receiving signal processing (fifth control signal) with higher priority than the second control signal (key distillation data). This reduces situations where, for example, the key distillation process is delayed (waiting time) or signal is lost due to the control signal for receiving signal processing required for the key distillation process not being received.

[0041] In this case, the forwarding unit 114A may, for example, use DiffServ (Differentiated Services) to preferentially forward the fifth control signal. In this case, the key distillation processing unit 121A may, for example, add a value indicating priority to each packet (frame) of the fifth control signal and the second control signal and send them to the forwarding unit 114A. The value indicating priority may be, for example, a CoS (Class of Service) value, which represents the priority of the data at Layer 2. Alternatively, the value indicating priority may be, for example, a DSCP (Diffserv Code Point) value, which represents the priority of the data at Layer 3, or a Precedence value.

[0042] Next, the OSC transceiver 115A uses the receiving optical fiber FRA to convert the optical signal 212 (downlink OSC optical signal) received from another optical communication device 11B at the OSC reception wavelength (5th wavelength) into an electrical signal and outputs it to the transfer unit 114A (step S105). Here, the transfer unit 114A transfers the packet to the OSC processing unit 113A or the key distillation processing unit 121A based on the destination information of the packet received from the OSC transceiver 115A. The destination information of the packet may be, for example, an IP (Internet Protocol) address, a combination of an IP address and a port number, or a MAC (Media Access Control) address.

[0043] When the transfer unit 114A receives an OSC control signal (third control signal) addressed to the OSC processing unit 113A from the optical communication device 11B, it transfers the third control signal to the OSC processing unit 113A. The OSC processing unit 113A then performs control related to the optical signal for data communication based on the third control signal.

[0044] Furthermore, if the transfer unit 114A receives a control signal (fourth control signal) addressed to the key distillation processing unit 121A from the optical communication device 11B, it transfers the fourth control signal to the key distillation processing unit 121A. The key distillation processing unit 121A then performs the QKD key distillation process based on the fourth control signal.

[0045] (Example of changing wavelength) The optical communication device 11A may determine (set, change) the wavelength of other optical signals sent from optical communication device 11A to optical communication device 11B based on the wavelength of the optical signal used for data communication from optical communication device 11A to optical communication device 11B. This allows, for example, the use of wavelengths in which quality degradation due to natural Raman scattering, etc., is relatively reduced, depending on the availability of wavelengths used for data communication.

[0046] In this case, the optical communication device 11A may determine the third wavelength of the optical signal 203 (quantum optical signal) used in the quantum channel from the quantum key distribution device 12A to the quantum key distribution device 12B based on the first wavelength used in the optical signal 201 (uplink WDM optical signal). Alternatively, the optical communication device 11A may determine the wavelength (second wavelength) for OSC transmission used in transmitting the first control signal, the second control signal, and the fifth control signal based on the first wavelength.

[0047] <Other> In recent years, in order to reduce the cost of laying dedicated fibers for QKD systems, a system that wavelength-multiplexes QKD systems within fibers that accommodate general-purpose optical transmission systems (QKD over WDM) has been researched and developed. In this system, the QKD equipment is installed in the same building where the WDM equipment is located, and the WDM optical signal and the quantum optical signal are wavelength-multiplexed using the WDM multiplexing / demultiplexing function and transmitted within the same fiber.

[0048] This study examines the case where five optical signals—a WDM optical signal for data communication (e.g., C-band 80 wavelengths, wavelengths 1529-1564 nm), an OSC optical signal (e.g., wavelength 1510 nm), a control signal for QKD (e.g., wavelength 1565 nm), a quantum optical signal (e.g., wavelength 1550 nm), and a control signal for receiving signals of the quantum channel (e.g., wavelength 1555 nm)—are multiplexed at different wavelengths. The optical signal for the control signal for receiving signals of the quantum channel, which is the classical QKD channel, is generated by slow intensity modulation and wavelength multiplexed. In this case, it is possible that the performance of the QKD, such as the key generation rate, may deteriorate due to natural Raman scattering caused by the optical signal for receiving signals of the quantum channel. Furthermore, it is possible that the quality of the WDM optical signal for data communication may deteriorate due to nonlinear optical effects in the optical fiber caused by the control signal for receiving signals of the quantum channel.

[0049] On the other hand, according to this disclosure, control signals for processing received signals of a quantum channel are transmitted by wavelength multiplexing with the OSC optical signal. This allows for appropriate quantum key distribution, for example, via an optical wavelength division multiplexing link.

[0050] <Hardware Configuration> At least some of the functions of the communication device 10 according to this embodiment may be realized through the cooperation of software and a computer, which is hardware. Figure 4 is a diagram showing an example of the hardware configuration of the computer 100 that the communication device 10 according to this embodiment has. In the example of Figure 4, the computer 100 includes a processor 101, memory 102, and a communication interface 103. These parts may be connected by a bus or the like. The memory 102 stores at least a portion of the program 104. The communication interface 103 includes an interface necessary for communication with other network elements.

[0051] When program 104 is executed in cooperation with the processor 101 and memory 102, etc., the computer 100 performs at least some of the processing of embodiments of this disclosure. Memory 102 may be of any type. Memory 102 may, in non-limiting examples, be a non-temporary computer-readable storage medium. Memory 102 may also be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. Although only one memory 102 is shown for computer 100, computer 100 may have several physically different memory modules. Processor 101 may be of any type. Processor 101 may include one or more general-purpose computers, dedicated computers, microprocessors, digital signal processors (DSPs), and, in non-limiting examples, processors based on multicore processor architectures. Computer 100 may have multiple processors, such as application-specific integrated circuit chips that are time-dependent to a clock that synchronizes the main processor.

[0052] Embodiments of the present disclosure may be implemented in hardware or in dedicated circuitry, software, logic, or any combination thereof. Some embodiments may be implemented in hardware, while others may be implemented in firmware or software that can be executed by a controller, microprocessor, or other computing device.

[0053] This disclosure also provides at least one computer program product tangibly stored on a non-temporary computer-readable storage medium. The computer program product includes computer-executable instructions, such as instructions contained in a program module, and is executed on a device on a target real or virtual processor to perform the processes or methods of this disclosure. The program module includes routines, programs, libraries, objects, classes, components, data structures, etc., that perform a specific task or implement a specific abstract data type. The functionality of the program module may be combined or divided among the program module as desired in various embodiments. The machine-executable instructions of the program module can be executed on a local or distributed device. On a distributed device, the program module can reside on both local and remote storage media.

[0054] Program code for performing the methods of this disclosure may be written in any combination of one or more programming languages. These program codes are provided to a processor or controller of a general-purpose computer, a dedicated computer, or other programmable data processing device. When the program code is executed by the processor or controller, the functions / operations in the flowchart and / or block diagrams it implements are performed. The program code may run entirely on a machine, partially on a machine, partially as a standalone software package, partially on a machine, partially on a remote machine, or entirely on a remote machine or server.

[0055] The program, when loaded into a computer, includes a set of instructions (or software code) for causing the computer to perform one or more of the functions described in the embodiments. The program may be stored on a non-temporary computer-readable medium or a physical storage medium. Examples, but not limited to, include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technologies, CD-ROM, digital versatile disc (DVD), Blu-ray® disc or other optical disc storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage devices. The program may be transmitted over a temporary computer-readable medium or a communication medium. Examples, but not limited to, include temporary computer-readable medium or a communication medium that includes electrically, optically, acoustically or otherwise propagating signals.

[0056] <Variation> The communication device 10 may be a device contained in a single housing, but the communication device 10 of this disclosure is not limited to this. Each part of the communication device 10 may be implemented by cloud computing, for example, consisting of one or more computers.

[0057] Furthermore, the optical communication device 11A and the quantum key distribution device 12A of the communication device 10A may be housed in different enclosures or in the same enclosure. Similarly, the optical communication device 11B and the quantum key distribution device 12B of the communication device 10B may be housed in different enclosures or in the same enclosure. Such communication devices 10 are also included as examples of "communication devices" in this disclosure.

[0058] Although the present disclosure has been described above with reference to embodiments, the present disclosure is not limited to the embodiments described above. Various modifications to the structure and details of the present disclosure can be made as can be understood by those skilled in the art within the scope of the present disclosure. Furthermore, each embodiment can be combined with other embodiments as appropriate.

[0059] Some or all of the embodiments described above may also be described as follows, but are not limited to the following. Some or all of the elements (e.g., configuration and function) described in each appendix dependent on Appendix 1 may also be dependent on other independent appendices of other categories in a similar manner. Some or all of the elements described in any appendix may be applicable to various hardware, software, recording means, systems, and methods for recording software. (Note 1) The system communicates an optical signal based on an electrical signal, which is a multiplexed electrical signal consisting of a first control signal from the first optical communication device to the second optical communication device and a control signal for receiving signals from the first quantum key distribution device to the second quantum key distribution device. Communication device. (Note 2) The first control signal is multiplexed with priority over the control signal for receiving the signal. The communication device described in Appendix 1. (Note 3) The control signal for receiving signal processing includes at least one of a clock signal, a bit position synchronization signal, and a bit error rate estimation signal. Communication device as described in Appendix 1 or 2. (Note 4) The system comprises the first optical communication device and the first quantum key distribution device, The optical signal is transmitted from the first optical communication device to the second optical communication device. Communication device as described in Appendix 1 or 2. (Note 5) Based on the data size of the stored quantum keys, the priority for multiplexing the control signals for processing the received signal is determined. Communication device as described in Appendix 1 or 2. (Note 6) If the data size of the stored quantum key is greater than or equal to a threshold, the control signals for processing the received signal are multiplexed with first priority. If the data size of the stored quantum key is not greater than or equal to the threshold, the control signal for processing the received signal is multiplexed with a second priority that is higher than the first priority. The communication device described in Appendix 5. (Note 7) The first control signal, the control signal for processing the received signal, and the key distillation data in the quantum key distribution (QKD) from the first quantum key distribution device to the second quantum key distribution device are multiplexed together. The control signal for processing the received signal is multiplexed with priority over the key distillation data. Communication device as described in Appendix 1 or 2. (Note 8) The system comprises the second optical communication device and the second quantum key distribution device, The optical signal from the first optical communication device is received by the second optical communication device. Communication device as described in Appendix 1 or 2. (Note 9) The system communicates an optical signal based on an electrical signal, which is a multiplexed electrical signal consisting of a first control signal from the first optical communication device to the second optical communication device and a control signal for receiving signals from the first quantum key distribution device to the second quantum key distribution device. Communication method. (Note 10) The system includes a first communication device having a first optical communication device and a first quantum key distribution device, and a second communication device having a second optical communication device and a second quantum key distribution device, The first communication device is The first control signal from the first optical communication device to the second optical communication device and the control signal for processing the received signal from the first quantum key distribution device to the second quantum key distribution device are multiplexed together. An optical signal based on multiplexed electrical signals is transmitted from the first optical communication device to the second optical communication device. Communication system. [Explanation of Symbols]

[0060] 1. Communication System 10A Communication device 11A Optical communication equipment 12A Quantum key distribution device FSA Transmitting Optical Fiber FRA receiving optical fiber 111A Transmitter Amplifier 112A receiving amplifier 113A OSC Processing Unit 114A Transfer section 115A OSC Transceiver 10B Communication device 11B Optical communication equipment 12B Quantum key distribution device FSB Transmitting Optical Fiber FRB receiving optical fiber 111B Transmission amplifier 112B Receiving Amplifier 113B OSC Processing Unit 114B Transfer section 115B OSC Transceiver Unit 30 servers F1-F3 Optical Communication Network

Claims

1. The system communicates an optical signal based on an electrical signal, which is a multiplexed electrical signal consisting of a first control signal from the first optical communication device to the second optical communication device and a control signal for receiving signals from the first quantum key distribution device to the second quantum key distribution device. Communication device.

2. The first control signal is multiplexed with priority over the control signal for receiving the signal. The communication device according to claim 1.

3. The control signal for receiving signal processing includes at least one of a clock signal, a bit position synchronization signal, and a bit error rate estimation signal. The communication device according to claim 1 or 2.

4. The system comprises the first optical communication device and the first quantum key distribution device, The optical signal is transmitted from the first optical communication device to the second optical communication device. The communication device according to claim 1 or 2.

5. Based on the data size of the stored quantum keys, the priority for multiplexing the control signals for processing the received signal is determined. The communication device according to claim 1 or 2.

6. If the data size of the stored quantum key is greater than or equal to a threshold, the control signals for processing the received signal are multiplexed with first priority. If the data size of the stored quantum key is not greater than or equal to the threshold, the control signal for processing the received signal is multiplexed with a second priority that is higher than the first priority. The communication device according to claim 5.

7. The first control signal, the control signal for receiving signal processing, and the key distillation data in quantum key distribution (QKD) from the first quantum key distribution device to the second quantum key distribution device are multiplexed together. The control signal for processing the received signal is multiplexed with priority over the key distillation data. The communication device according to claim 1 or 2.

8. The system comprises the second optical communication device and the second quantum key distribution device, The optical signal from the first optical communication device is received by the second optical communication device. The communication device according to claim 1 or 2.

9. The system communicates an optical signal based on an electrical signal, which is a multiplexed electrical signal consisting of a first control signal from the first optical communication device to the second optical communication device and a control signal for receiving signals from the first quantum key distribution device to the second quantum key distribution device. Communication method.

10. The system includes a first communication device having a first optical communication device and a first quantum key distribution device, and a second communication device having a second optical communication device and a second quantum key distribution device. The first communication device is The first control signal from the first optical communication device to the second optical communication device and the control signal for receiving the signal from the first quantum key distribution device to the second quantum key distribution device are multiplexed together. An optical signal based on multiplexed electrical signals is transmitted from the first optical communication device to the second optical communication device. Communication system.

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