Abstract: A communication system includes a master device, a slave device, and a relay device. The relay device includes a time synchronization management unit that stores retention time of a first time-synchronization frame sent from the master device, adds the first-time-synchronization-frame retention time to a correction field when a second time-synchronization frame sent from the master device is relayed, stores retention time of a third time-synchronization frame sent from the slave device, and adds the third-time-synchronization-frame retention time to a correction field when a fourth time-synchronization frame sent from the master device is relayed.

Abstract: A management device for managing a radio access network includes: a RAN slice management unit configured to manage a slice of the radio access network; a radio resource management unit configured to abstract and manage a radio resource possessed by a radio base station included in a radio network; an optical resource management unit configured to abstract and manage an optical resource possessed by an optical communication device included in an optical network; and a base station resource management unit configured to abstract and manage a base station resource possessed by a base station device included in a base station network. When a slice generation request is received from a higher-level management device, the RAN slice management unit determines an abstracted radio resource, an abstracted optical resource and an abstracted base station resource to be assigned to a slice, based on requested performance of the slice.

Abstract: A management device for managing a radio access network includes: a RAN slice management unit configured to manage a slice of the radio access network; a radio resource management unit configured to abstract and manage a radio resource possessed by a radio base station included in a radio network; an optical resource management unit configured to abstract and manage an optical resource possessed by an optical communication device included in an optical network; and a base station resource management unit configured to abstract and manage a base station resource possessed by a base station device included in a base station network. When a slice generation request is received from a higher-level management device, the RAN slice management unit determines an abstracted radio resource, an abstracted optical resource and an abstracted base station resource to be assigned to a slice, based on requested performance of the slice.

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 ONU includes a CDR that regenerates a clock based on a signal from an OLT, an oscillator that generates an internal clock, a time stamp counter that manages a time of the ONU based on the clock in a period in which the CDR regenerates the clock and manages the time of the ONU based on the internal clock in a period in which the CDR does not regenerate the clock, an MPCP control unit that decides, when a Cyclic Sleep mode is set, a receiver-time synchronization time that is a period in which the receiver is normally operated within a sleep time, based on a difference between a time stamp value included in the signal transmitted from the OLT and a time stamp managed by the time stamp counter, and a power-saving control unit that controls the receiver to be normally operated in the receiver-time synchronization time.

Abstract: A station side device includes a first requesting unit that requests a counterpart communication device to perform a power saving operation of alternately performing execution and suspension of communication at preset time intervals; a phase specifying unit that specifies a first phase of the power saving operation performed by the counterpart communication device and a second phase corresponding to the first phase in the power saving operation of the station side device, based on communication performed with the counterpart communication device; a time-difference calculating unit that calculates a difference between the first phase and the second phase; and a second requesting unit that requests again the counterpart communication device to perform the power saving operation based on the calculated difference.

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 ONU includes a CDR that regenerates a clock based on a signal from an OLT, an oscillator that generates an internal clock, a time stamp counter that manages a time of the ONU based on the clock in a period in which the CDR regenerates the clock and manages the time of the ONU based on the internal clock in a period in which the CDR does not regenerate the clock, an MPCP control unit that decides, when a Cyclic Sleep mode is set, a receiver-time synchronization time that is a period in which the receiver is normally operated within a sleep time, based on a difference between a time stamp value included in the signal transmitted from the OLT and a time stamp managed by the time stamp counter, and a power-saving control unit that controls the receiver to be normally operated in the receiver-time synchronization time.