Abstract: An ONU receiving an optical signal from an OLT including PON controllers includes: an optical receiver to convert, into an electric signal, an optical signal having a single optical wavelength set out of plural optical wavelengths; and a control frame extractor to extract and hold wavelength correspondence information indicating correspondence between MAC addresses of the PON controllers received from the OLT and the optical wavelengths.

Abstract: An ONU receiving an optical signal from an OLT including PON controllers includes: an optical receiver to convert, into an electric signal, an optical signal having a single optical wavelength set out of plural optical wavelengths; and a control frame extractor to extract and hold wavelength correspondence information indicating correspondence between MAC addresses of the PON controllers received from the OLT and the optical wavelengths.

Abstract: An ONU communicates with an OLT that can transmit optical signals having different wavelengths simultaneously and receive optical signals having different wavelengths simultaneously. The ONU includes: an optical transceiver that receives any one of the optical signals that the OLT can transmit and transmits any one of the optical signals that the OLT can receive; a communication failure detection unit that detects a communication failure between the OLT and the ONU; and a wavelength selection unit that, when the communication failure detection unit detects a communication failure, changes a setting of a downstream wavelength to be received by the optical transceiver and an upstream wavelength to be transmitted by the optical transceiver.

Abstract: A communication system in which a master station device is connected to a plurality of slave station devices by an optical transmission line and a plurality of wavelengths are used to perform at least one of downstream communication and upstream communication. The master station device includes: a control unit that assigns a wavelength to be used in communication to the slave station device, and that generates a control signal for notifying the slave station device of the assigned wavelength; and an optical transmitter that transmits the control signal generated by the control unit to the slave station device. The slave station device includes an optical receiver and an optical transmitter that carry out communication with the master station device using the wavelength based on the control signal received from the master station device.

Abstract: An ONU communicates with an OLT that can transmit optical signals having different wavelengths simultaneously and receive optical signals having different wavelengths simultaneously. The ONU includes: an optical transceiver that receives any one of the optical signals that the OLT can transmit and transmits any one of the optical signals that the OLT can receive; a communication failure detection unit that detects a communication failure between the OLT and the ONU; and a wavelength selection unit that, when the communication failure detection unit detects a communication failure, changes a setting of a downstream wavelength to be received by the optical transceiver and an upstream wavelength to be transmitted by the optical transceiver.

Abstract: A communication system in which a master station device is connected to a plurality of slave station devices by an optical transmission line and a plurality of wavelengths are used to perform at least one of downstream communication and upstream communication. The master station device includes: a control unit that assigns a wavelength to be used in communication to the slave station device, and that generates a control signal for notifying the slave station device of the assigned wavelength; and an optical transmitter that transmits the control signal generated by the control unit to the slave station device. The slave station device includes an optical receiver and an optical transmitter that carry out communication with the master station device using the wavelength based on the control signal received from the master station device.

Abstract: An ONU communicates with an OLT that can transmit optical signals having different wavelengths simultaneously and receive optical signals having different wavelengths simultaneously. The ONU includes: an optical transceiver that receives any one of the optical signals that the OLT can transmit and transmits any one of the optical signals that the OLT can receive; a communication failure detection unit that detects a communication failure between the OLT and the ONU; and a wavelength selection unit that, when the communication failure detection unit detects a communication failure, changes a setting of a downstream wavelength to be received by the optical transceiver and an upstream wavelength to be transmitted by the optical transceiver.

Abstract: A communication method of an optical communication system in which a user-side optical-line terminal apparatus (ONU) is connected to a station-side optical-line terminal apparatus (OLT) by an optical fiber includes allocating by the OLT to the ONY a transmission bandwidth for transmitting a response signal in a tentative wake-up period in a sleep mode in which a transmission function of the ONU is activated in the tentative wake-up period and deactivated in a sleep period. The method also includes transmitting a transmission bandwidth notification to the ONU, and transmitting, to the ONU, a notification of the sleep period in which deactivation of the transmission function is allowed.

Abstract: An OLT includes an OLT control unit that generates a control signal for controlling a power saving operation of an ONU by specifying a different idle period with respect to a first power saving operation in which an optical receiver is operated while an optical transmitter of the ONU is controlled to a power saving state and a second power saving operation for controlling the optical transmitter and the optical receiver to the power saving state, and a station-side transmitter that transmits the control signal generated by the OLT control unit to the ONU. The ONU includes an ONU control unit that receives the control signal via the optical receiver to selectively perform the first power saving operation and the second power saving operation based on the idle period specified by the control signal.

Abstract: An optical communication system that connects a plurality of user-side optical line terminating apparatuses (hereinafter referred to as ONUs) to a station-side optical line terminating apparatus (hereinafter referred to as OLT) using a common optical fiber, wherein the ONU as at least a part of the ONUs includes a transceiver having a power saving function for inactivating a transmitting unit while supplying electric power to a receiving unit and a control apparatus that transmits support information of the power saving function to the OLT via the transceiver, and the OLT includes a control apparatus that generates transmission allowance information of upstream communication based on the support information of the power saving function and a transceiver that receives the support information of the power saving function and transmits the transmission allowance information to the ONU.

Abstract: In a PON system, an ONU includes a receive buffer that stores therein a signal in a downstream direction transmitted from an OLT and a PON control unit that controls transition to a power-saving state and transition to a normal state for the reception buffer. The OLT includes a transmission buffer that stores transmission data to be transmitted to the ONU and the PON control unit that transmits the downstream power-saving-state transition request that requests the ONU to transition to the downstream power-saving state when it is determined that transmission data addressed to the ONU is not present in the transmission buffer. The PON control unit sets the reception buffer to a power-saving state for a predetermined downstream sleep time requested based on the downstream power-saving-state transition request.

Abstract: An ONU includes a power-interruption detecting unit configured to detect power interruption of the ONU, a transmitting and receiving unit capable of being set in a power saving state, and a PON-side control unit configured to notify an OLT of, as power saving return information, a power holding time during occurrence of the power interruption of the ONU and a startup time, which is time until the transmitting and receiving unit returns from the power saving state, and, when the power-interruption detecting unit detects the power interruption, transmit a power interruption notification to the OLT. The OLT includes the PON control unit configured to determine, based on the power saving return information, whether the ONU can transmit the power interruption notification when the power interruption occurs in the power saving state.

Abstract: A communication system in which a master station device is connected to a plurality of slave station devices by an optical transmission line and a plurality of wavelengths are used to perform at least one of downstream communication and upstream communication. The master station device includes: a control unit that assigns a wavelength to be used in communication to the slave station device, and that generates a control signal for notifying the slave station device of the assigned wavelength; and an optical transmitter that transmits the control signal generated by the control unit to the slave station device. The slave station device includes an optical receiver and an optical transmitter that carry out communication with the master station device using the wavelength based on the control signal received from the master station device.

Abstract: An optical communication system connects a plurality of user-side optical line terminating apparatuses (hereinafter referred to as ONUs) to a station-side optical line terminating apparatus (hereinafter referred to as OLT) using a common optical fiber. At least a part of the ONUs includes a transceiver having a power saving function for inactivating a transmitting unit while supplying electric power to a receiving unit and a control apparatus that transmits support information of the power saving function to the OLT via the transceiver, and the OLT includes a control apparatus that generates transmission allowance information of upstream communication based on the support information of the power saving function and a transceiver that receives the support information of the power saving function and transmits the transmission allowance information to the ONU.

Abstract: An OLT includes an OLT control unit that generates a control signal for controlling a power saving operation of an ONU by specifying a different idle period with respect to a first power saving operation in which an optical receiver is operated while an optical transmitter of the ONU is controlled to a power saving state and a second power saving operation for controlling the optical transmitter and the optical receiver to the power saving state, and a station-side transmitter that transmits the control signal generated by the OLT control unit to the ONU. The ONU includes an ONU control unit that receives the control signal via the optical receiver to selectively perform the first power saving operation and the second power saving operation based on the idle period specified by the control signal.

Abstract: In a communication line switching method for an optical communications system in which a station-side line terminal apparatus and user-side line terminal apparatuses are connected via a plurality of redundant physical lines, the discovery of the station-side optical line terminal registering the user-side line terminal apparatuses, wherein the registered user-side line terminal apparatuses monitoring a time stamp drift error that is generated when a difference between a time stamp included in a received signal and a local time measured by the own apparatus is larger than a value set in advance and, when the time stamp drift error occurs, shifting to a deregistered state and waiting for registration by the discovery. The station-side line terminal apparatus switches a physical line from a working physical line to a backup physical line of the physical lines.

Abstract: A communication device operating as a master unit includes: a MAC layer termination functioning unit for extracting, from a receiving signal, queue length information scheduled to be transmitted from an ONU, and controlling transmission of a grant to the ONU; a traffic monitor for measuring an amount of uplink traffic of each ONU; and a bandwidth allocation functioning unit for determining a bandwidth to be allocated to each ONU based on the queue length information extracted by the MAC layer termination functioning unit, the amount of traffic measured by the traffic monitor, and a bandwidth that can be allocated in one cycle of bandwidth update, and issuing a grant according to the determination. The bandwidth allocation functioning unit updates a bandwidth to be allocated periodically.

Abstract: In a communication line switching method for an optical communications system in which a station-side line terminal apparatus and user-side line terminal apparatuses are connected via a plurality of redundant physical lines, the discovery of the station-side optical line terminal registering the user-side line terminal apparatuses, wherein the registered user-side line terminal apparatuses monitoring a time stamp drift error that is generated when a difference between a time stamp included in a received signal and a local time measured by the own apparatus is larger than a value set in advance and, when the time stamp drift error occurs, shifting to a deregistered state and waiting for registration by the discovery. The station-side line terminal apparatus switches a physical line from a working physical line to a backup physical line of the physical lines.

Abstract: A communication method of an optical communication system in which a plurality of ONUs are connected to an OLT, includes steps (a) allocating, by the OLT, a transmission bandwidth to an ONU capable of an operation in a sleep mode in which an optical transmitter is tentatively halted for a predetermined sleep period, and transmitting a transmission bandwidth notification to the ONU when the ONU is in the sleep mode and when the ONU is not in the sleep mode; (b) receiving, from the ONU to which the transmission bandwidth is allocated, a response signal when the ONU is not in the sleep mode, wherein the response signal is or is not received during the sleep mode; and (c) suppressing, by the OLT, an alarm in the sleep mode, the alarm being caused by a communication failure with the ONU on a basis of the response signal not being received.

Abstract: A communication system in which a plurality of user-side optical line terminating apparatuses (Optical Network Units, hereinafter referred to as ONUs) and station-side optical line terminating apparatus (Optical Line Terminal, hereinafter referred to as OLT) are connected with a common optical fiber. The ONUs each includes: an ONU side optical transceiver having a transmitting function capable of being stopped and waked in a power saving mode to reduce power consumption; and an ONU control device configured to stop the transmitting function of the ONU side optical transceiver in a period designated by the OLT via the ONU side optical transceiver. The OLT includes: an OLT side optical transceiver connected to the optical fiber; and an OLT control device configured to designate the period the ONU stops the transmitting function of the ONU side optical transceiver to the ONU via the OLT side optical transceiver.