Patent ID: 8582970

Claim:
An office-side line concentration device that accommodates a plurality of passive optical networks in which all transfer rates of user data are identical, the office-side line concentration device comprising: a plurality of receivers connected to each of the plurality of passive optical networks; and interface means for controlling transmission timing of burst signals from the plurality of passive optical networks so that user data included in a burst signal of a first passive optical network in the plurality of passive optical networks and user data included in a burst signal of a second passive optical network in the plurality of passive optical networks are arranged at an interval shorter than a total of a laser-on period, a synchronization period, and a report frame sending periods in an uplink in which an upstream transfer rate of user data is identical to all upstream transfer rates of the plurality of passive optical networks, wherein the interface means comprises means for selecting a time obtained by subtracting a predetermined time up to a time corresponding to the total time from a last allocated start time of a laser-off period in the burst signal of the first passive optical network as a start time for sending the burst signal of the second passive optical network.