SUBSCRIBER-SIDE OPTICAL COMMUNICATION DEVICE, COMMUNICATION SYSTEM, CONTROL DEVICE AND POWER-SAVING CONTROL METHOD

摘要

This ONU (2) is capable of individually putting a receiver (221) and a transmitter (222) of an optical transmission and reception module (202) into power-saving states. The ONU (2) is provided with: a CDR (203) which performs clocking on the basis of a signal from an OLT (1); an oscillator/oscillation element (207) for generating an internal clock; a timestamp counter (209) which, during the period in which the CDR (203) is recovering the clock, manages the time of the device itself on the basis of the clock, and during the period in which the clock is not being recovered at the CDR (203), manages the time of the device itself on the basis of the internal clock; an MPCP control unit (208) which, if Cyclic Sleep mode has been set, on the basis of the difference between a timestamp value included in the signal transmitted from the OLT (1) and a timestamp managed by the timestamp counter (209), determines a receiver time synchronization time period, which is a period for which the receiver (221) is caused to operate normally within a sleep time period; and a power-save control unit (212) which controls the receiver (221) so as to operate normally during the receiver time synchronization time period.