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.

Abstract: An ONU includes the optical transceiver capable of an operation in a power-saving mode in which power consumption is reduced by stopping transmission while continuing reception, and a control device that controls to tentatively validate transmission of the optical transceiver and outputs a response signal when a control signal is received from an OLT during an operation in a power-saving state. Moreover, the OLT includes the control device that allocates a transmission bandwidth to the ONU even while the optical transceiver of the ONU operates in a power-saving mode and stops transmission and determines whether a communication failure occurs or the ONU is in operation in a power-saving mode based on the response signal received by a transceiver of the OLT.

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: An optical line terminal performs transmission to optical network units using a light signal having a wavelength different for each of systems, allocates communication time to data, which is transmitted from the optical network units, in a time division manner for each of the systems, selects, for each of the optical network units, a system for performing data transmission, and transmits the data using a wavelength corresponding to the selected system. The optical network unit includes: ith blocking filter that removes a component other than a component in a predetermined wavelength band, which is set to correspond to an ith system, from a received light signal; and ith PON processing unit that applies termination processing to signals and transmitting the data based on an allocation result of the optical line terminal. The PON system includes n optical network units corresponding to i=1 to i=n.

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 combination of redundant configurations of communication lines and a power-saving-mode operating function is incorporated, and includes a power-saving-device identification unit that identifies a slave station device in a power saving mode, and a line switching unit that switches a communication line forming a communication route from the currently used communication line to the backup communication line when a state where a master station device does not receive a signal from any of a plurality of slave station devices except for the slave station device identified by the power-saving-device identification unit as being in the power saving mode among the slave station devices continues for a predetermined time.

Abstract: The control device includes a power-saving control unit that intermittently repeats, based on a power saving permission signal transmitted from the master station apparatus, power saving control in which the slave station stops or reduces power supply to a transmitter or a receiver for a predetermined pause duration while maintaining a communication link and a monitoring unit that monitors out of synchronization by comparing a synchronization signal received from the OLT and a time of the ONU. The control device shifts from a registered state to a deregistered state when the monitoring unit detects the out of synchronization. On the other hand, after the pause duration of the power saving control, the control device suppresses the shift to the deregistered state due to the detection of the out of synchronization.

Abstract: A communication control method performing Discovery processing, which is a procedure at an OLT to detect an ONU newly connected, in a PON system, the method includes: a transmission-permission-signal transmitting step of transmitting, by the OLT, a transmission permission signal for discovery, which includes an individual number of an ONU that is permitted to respond and mask information for designating a match-detection target bit for the individual number; and a registration-request-signal transmitting step of comparing, by an ONU, which is not registered in the OLT, a match-detection target bit for the individual number designated in the mask information with an individual number of the ONU based on a received transmission permission signal, and when the target bit and the individual number match each other, transmitting a registration request signal to the OLT.

Abstract: In a communication system in which a station-side line terminal apparatus 1 and a user-side line terminal apparatus 10 perform communication via a plurality of redundant physical lines, the user-side line terminal apparatus 10 monitors an out-of-synchronization error and line abnormality of the physical lines and, when line abnormality is detected (P4), shifts from a registered state to a holdover state for deferring discarding of setting information such as link information. The user-side line terminal apparatus 10 suppresses detection of the out-of-synchronization error during a deferred period to prevent a communication link from being disconnected by the out-of-synchronization error and prevent initial setting from being required. The station-side line terminal apparatus 1 switches a line during the deferred period (P7) and, after transmitting a synchronization signal (P8) to synchronize with the user-side line terminal apparatus, resumes normal communication.

Abstract: The control device includes a power-saving control unit that intermittently repeats, based on a power saving permission signal transmitted from the master station apparatus, power saving control in which the slave station stops or reduces power supply to a transmitter or a receiver for a predetermined pause duration while maintaining a communication link and a monitoring unit that monitors out of synchronization by comparing a synchronization signal received from the OLT and a time of the ONU. The control device shifts from a registered state to a deregistered state when the monitoring unit detects the out of synchronization. On the other hand, after the pause duration of the power saving control, the control device suppresses the shift to the deregistered state due to the detection of the out of synchronization.

Abstract: An ONU includes the optical transceiver capable of an operation in a power-saving mode in which power consumption is reduced by stopping transmission while continuing reception, and a control device that controls to tentatively validate transmission of the optical transceiver and outputs a response signal when a control signal is received from an OLT during an operation in a power-saving state. Moreover, the OLT includes the control device that allocates a transmission bandwidth to the ONU even while the optical transceiver of the ONU operates in a power-saving mode and stops transmission and determines whether a communication failure occurs or the ONU is in operation in a power-saving mode based on the response signal received by a transceiver of the OLT.

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 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: A passive optical network including: a parent station OLT (optical line terminal); and a plurality of child stations ONU (optical network terminating unit), wherein the parent station and the plurality of child stations transmit an upstream frame and a downstream frame to each other, and the parent station includes means for generating a maintenance signal indicating failure at a mini slot, corresponding to each of the plurality of child stations, on a basis of a receiving state of a signal at the mini slot sent from each of the plurality of child stations.

Abstract: In a PON system including a high-speed optical signal of a high transmission speed and a low-speed optical signal the speed of which is lower than that of the high-speed optical signal, the PON system employing TDMA system for upward signal transmission, an OLT controls transmission and reception of the low-speed optical signal and the high-speed optical signal and allocates a grant to a slave station unit connected to the OLT.

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.