Abstract: An optical transmitter (3) tracks a moving body (1) and irradiates the moving body (1) with a laser beam (4). An optical receiver (5) is mounted on the moving body (1), receives the laser beam (4), and performs optical space communication with the optical transmitter (3). The optical transmitter (3) extends an irradiation range (6) of the laser beam (4) into an elliptical shape.

Abstract: A control device includes: a distance derivation part which derives a communication distance between a subject-communication device which communicates using a beam and another communication device which faces the subject communication device; a speed derivation part which derives a relative speed of the another communication device with respect to the subject communication device; an angle derivation part which derives a range of divergence angles of a beam in which it is possible to maintain communication between the subject communication device and the another communication device on the basis of at least the communication distance and the relative speed; and an angle control part which changes a divergence angle of the beam when it is determined that the divergence angle needs to be changed on the basis of the current divergence angle of the beam and the range.

Abstract: A spatial optical communication system in which a plurality of transmitters and a plurality of receivers opposite to each of the plurality of transmitters perform an optical communication in parallel, in which the plurality of transmitters transmit optical signals of same or adjacent wavelengths to the receivers of each opposite location, and has an interference blocking unit which is disposed between the transmitter and the receiver and spatially blocks an optical signal that interferes with the receiver of a non-opposite location among optical signals transmitted from the transmitter to the receiver of an opposite location. As a result, it is possible to avoid interference with other optical communications with a reduced space and at low cost, without need to supply power.

Abstract: A wavelength multiplexing communication system includes a master station apparatus and a plurality of slave station apparatuses. The master station apparatus includes a wavelength multiplexing communication unit. The wavelength multiplexing communication unit performs wavelength multiplexing communication with the plurality of slave station apparatuses by using optical signals having the number of wavelengths equal to or less than the number of the plurality of slave station apparatuses. The slave station apparatus includes an optical communication unit. When the main signal communication is performed in the host slave station apparatus, the optical communication unit communicates with the master station apparatus by an optical signal having the same wavelength as a wavelength used by another slave station apparatus in which a main signal notification is not performed.

Abstract: According to an embodiment, an optical space communication device includes: an optical antenna configured to receive laser light emitted by multiplexing a main signal to be communicated and a control signal used to maintain or control communication; an optical branching element configured to branch the laser light received by the optical antenna into a plurality of pieces of laser light; a first optical fiber configured to transmit one of the pieces of laser light branched by the optical branching element to a light reception element; a second optical fiber configured to have a larger core diameter than a core diameter of the first optical fiber and transmit another piece of laser light branched by the optical branching element to the light reception element; and an extraction unit configured to extract the control signal from the other piece of laser light transmitted by the second optical fiber.

Abstract: A switch in a communication network comprises a controller for controlling a communication flow in the communication network. A suspected flow is a communication flow suspected of being related to a DDoS (Distributed Denial of Service) attack. A normal flow is a communication flow other than the suspected flow. The controller is configured to execute provisional handling when receiving a provisional handling instruction indicating identification information of the suspected flow from a network controller. The provisional handling includes processing of setting a priority of the suspected flow to a designated priority, and processing of setting a priority of the normal flow higher than the designated priority.

Abstract: The present invention enables shortening the time required for resuming communication in a protection method that uses a backup path in an optical communication system that includes a master station device and multiple slave station devices. The slave station devices are connected to a loop path in parallel. The communication paths between the master station device and the slave station devices include a normal path and a backup path. First and second slave station devices are slave station devices that cannot perform communication via the normal path. The magnitude relationship between backup path RTTs is opposite to the magnitude relationship between normal path RTTs. If the second normal path RTT for the second slave station device is longer than the first normal path RTT for the first slave station device, the first backup path RTT is longer than the second backup path RTT, and the second backup path RTT is shorter than the first backup path RTT.

Abstract: Time taken for resuming communication in a protection scheme using a backup path in an optical communication system including a master station device and a plurality of slave station devices is decreased. The plurality of slave station devices are connected in parallel to a looped path. A communication path between the master station device and each of the slave station device includes a normal path and a backup path. The master station device performs communication control processing for each of the slave station device based on RTT. A first slave station device is a slave station device with which communication through the normal path has become impossible. First backup path RTT of the first slave station device is calculated based on first normal path RTT of the first slave station device, first partial RTT between the master station device and the looped path, and loop propagation time necessary for one trip through the looped path.

Abstract: A beam transmission device transmits a directional beam toward a beam reception device in a wireless communication system. The main signal generation unit generates a main signal. A control signal generation unit periodically generates a control signal related to maintaining communication with the beam reception device. A signal multiplexing unit multiplexes the main signal and the control signal. A divergence angle adjustment unit sets a target divergence angle to a first divergence angle in a period in which the control signal is not included in the multiplexed signal, and sets the target divergence angle to a second divergence angle larger than the first divergence angle in a period in which the control signal is included in the multiplexed signal. A beam control unit changes a divergence angle of the beam modulated by the multiplexed signal to the target divergence angle.

Abstract: According to an embodiment, an optical space communication device includes: an optical antenna configured to receive laser light emitted by multiplexing a main signal to be communicated and a control signal used to maintain or control the communication; an optical branching element configured to branch the laser light received by the optical antenna into first laser light and second laser light; a main signal extraction unit configured to extract the main signal based on the first laser light; a positional deviation detection unit configured to detect a positional deviation of the laser light based on the second laser light; and a control signal extraction unit configured to extract the control signal based on the second laser light.

Abstract: The present invention enables shortening the time required for resuming communication in a protection method that uses a backup path in an optical communication system that includes a master station device and multiple slave station devices. The slave station devices are connected to a loop path in parallel. The communication paths between the master station device and the slave station devices include a normal path and a backup path. The master station device executes communication control processing with respect to the slave station devices based on the RTTs. A first slave station device is a slave station device that cannot perform communication via the normal path. If the first slave station device is detected, the master station device calculates a first backup path for the first slave station device based on a first RTT between the master station device and the loop path, a loop RTT required for one full lap on the loop path, and the first normal path RTT for the first slave station device.

Abstract: A wavelength multiplexing communication system includes a master station apparatus and a plurality of slave station apparatuses. The master station apparatus includes a wavelength multiplexing communication unit that performs wavelength multiplexing communication with the plurality of slave station apparatuses by wavelengths the number of which is equal to or less than the number of the plurality of slave station apparatuses using an optical signal of a wavelength in a first wavelength group and an optical signal of a wavelength in a second wavelength group.

Abstract: An optical transmitter (3) tracks a moving body (1) and irradiates the moving body (1) with a laser beam (4). An optical receiver (5) is mounted on the moving body (1), receives the laser beam (4), and performs optical space communication with the optical transmitter (3). The optical transmitter (3) extends an irradiation range (6) of the laser beam (4) into an elliptical shape.

Abstract: In an optical communication system, an optical communication device and a plurality of optical transmission devices are loop-connected via transmission line. An optical signal transmission unit of the optical communication device, when no communication interruption occurs in the transmission line, outputs an optical signal addressed to a communication destination device that communicates with the own device to a transmission line connected to either one of two neighboring optical transmission devices. The optical signal transmission unit outputs, at the time of communication interruption occurring in the transmission line, an optical signal addressed to the communication destination device to both of transmission lines connected to respective two neighboring optical transmission devices.

Abstract: A transfer device installed between a host device and a plurality of OLTs in a communication system to which a network with a PON configuration including the plurality of OLTs between the host device and a subordinate device is applied, the transfer device including a frame information acquisition unit configured to monitor downstream frames input from the host device and calculate a statistical value of the downstream frames per a predetermined fixed cycle, a frame storage unit including a plurality of queues each configured to store downstream frames to be transferred to the plurality of OLTs, the frame storage unit configured to store the downstream frames input from the host device, a frame sorting unit configured to input the downstream frames to the plurality of queues in the frame storage unit, and a distribution control determination unit configured to determine the number of frames to be sequentially input by the frame sort unit to the plurality of queues based on the statistical value.

Abstract: A spatial optical communication system in which a plurality of transmitters and a plurality of receivers opposite to each of the plurality of transmitters perform an optical communication in parallel, in which the plurality of transmitters transmit optical signals of same or adjacent wavelengths to the receivers of each opposite location, and has an interference blocking unit which is disposed between the transmitter and the receiver and spatially blocks an optical signal that interferes with the receiver of a non-opposite location among optical signals transmitted from the transmitter to the receiver of an opposite location. As a result, it is possible to avoid interference with other optical communications with a reduced space and at low cost, without need to supply power.

Abstract: The present invention enables shortening the time required for resuming communication in a protection method that uses a backup path in an optical communication system that includes a master station device and multiple slave station devices. The slave station devices are connected to a loop path in parallel. The communication paths between the master station device and the slave station devices include a normal path and a backup path. The master station device executes communication control processing with respect to the slave station devices based on the RTTs. A first slave station device is one of the slave station devices, and a second slave station device is a slave station device that cannot perform communication via the normal path.

Abstract: The present invention enables shortening the time required for resuming communication in a protection method that uses a backup path in an optical communication system that includes a master station device and multiple slave station devices. The slave station devices are connected to a loop path in parallel. The communication paths between the master station device and the slave station devices include a normal path and a backup path. The master station device executes communication control processing with respect to the slave station devices based on the RTTs. A first slave station device is a slave station device that cannot perform communication via the normal path. If the first slave station device is detected, the master station device calculates a first backup path for the first slave station device based on a first RTT between the master station device and the loop path, a loop RTT required for one full lap on the loop path, and the first normal path RTT for the first slave station device.

Abstract: Time taken for resuming communication in a protection scheme using a backup path in an optical communication system including a master station device and a plurality of slave station devices is decreased. The plurality of slave station devices are connected in parallel to a looped path. A communication path between the master station device and each of the slave station device includes a normal path and a backup path. The master station device performs communication control processing for each of the slave station device based on RTT. A first slave station device is a slave station device with which communication through the normal path has become impossible. First backup path RTT of the first slave station device is calculated based on first normal path RTT of the first slave station device, first partial RTT between the master station device and the looped path, and loop propagation time necessary for one trip through the looped path.

Abstract: A wavelength multiplexing communication system includes a master station apparatus and a plurality of slave station apparatuses. The master station apparatus includes a wavelength multiplexing communication unit that performs wavelength multiplexing communication with the plurality of slave station apparatuses by wavelengths the number of which is equal to or less than the number of the plurality of slave station apparatuses using an optical signal of a wavelength in a first wavelength group and an optical signal of a wavelength in a second wavelength group.