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: 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: A relay device that relays communication between a low-speed communication device performing uplink 1 G transfer and a high-speed communication device performing uplink 10 G transfer and a station-side optical communication device, wherein the relay device includes a low-speed reception unit that converts an optical signal received from the low-speed communication device to an electric signal, a buffer that buffers the electric signal, and a high-speed transmission unit that transmits, to the station-side optical communication device, a bandwidth allocation request requesting bandwidth allocation for communication from its own unit to the station-side optical communication device, and within a transmission permitted time period allocated by the station-side optical communication device, reads an electric signal stored in the buffer, converts the electric signal to an optical signal having a communication speed of 10 G, and transmits the optical signal.

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: 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: A logical-link management method to be executed in an optical communication system including a station side device (OLT) and a subscriber side device (ONU) that is capable of setting a plurality of logical links together with the OLT, in which the OLT transmits a signal for managing the ONU via a single logical link. The logical-link management method includes a status monitoring of the OLT monitoring whether there is a change in a connection status of the logical link between the OLT and the ONU and a link resetting of the OLT resetting, when a change of the connection status of the logical link is detected at the status monitoring, a device management logical link used for transmitting the signal for managing the ONU according to a predetermined procedure.

Abstract: A relay device that relays communication between a low-speed communication device performing uplink 1 G transfer and a high-speed communication device performing uplink 10 G transfer and a station-side optical communication device, wherein the relay device includes a low-speed reception unit that converts an optical signal received from the low-speed communication device to an electric signal, a buffer that buffers the electric signal, and a high-speed transmission unit that transmits, to the station-side optical communication device, a bandwidth allocation request requesting bandwidth allocation for communication from its own unit to the station-side optical communication device, and within a transmission permitted time period allocated by the station-side optical communication device, reads an electric signal stored in the buffer, converts the electric signal to an optical signal having a communication speed of 10 G, and transmits the optical signal.

Abstract: A logical-link management method to be executed in an optical communication system including a station side device (OLT) and a subscriber side device (ONU) that is capable of setting a plurality of logical links together with the OLT, in which the OLT transmits a signal for managing the ONU via a single logical link. The logical-link management method includes a status monitoring of the OLT monitoring whether there is a change in a connection status of the logical link between the OLT and the ONU and a link resetting of the OLT resetting, when a change of the connection status of the logical link is detected at the status monitoring, a device management logical link used for transmitting the signal for managing the ONU according to a predetermined procedure.

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 line termination includes a deserializer that parallelizes burst data received from a termination device, a fixed-pattern generating unit that generates fixed pattern data that is a predetermined fixed data, and a data selecting unit that selects either the fixed pattern data or the burst data based on a data-head instruction signal indicating a head of the burst data and a data-end instruction signal indicating an end of the burst data, and inputs the selected data to a deserializer as data to be parallelized.

Abstract: An OLT includes an upper-layer processing unit that receives a transmission request for notifying a data amount transmitted from an ONU and applies predetermined upper-layer processing to data received from the ONU. The OLT includes a band-allocation-information managing unit that instructs, based on the transmission request, when determining that a free period, which is a period in which a band is not allocated to data transmission from the ONU, equal to or larger than a predetermined band threshold is present, the upper-layer processing unit to shift a power saving state. The upper-layer processing unit shifts to the power saving state based on the instruction.