| 摘要 |
<p>An optical line terminal includes the transmission rate control table for storing a minimum bandwidth for an emergency status for each of optical network units in addition to a maximum assigned bandwidth in a normal status. When a decrease in a supply power is detected, the optical line terminal calculates a transmission clock rate providing a minimum bandwidth required by each optical network unit with reference to the transmission rate control table. The optical line terminal determines change timing of downstream and upstream transmission clock rates, and change timing of upstream data for time-division multiplexing to instruct each of the optical network units. Both the optical line terminal and the optical network unit change the transmission clock rates with substantial synchronization therebetween.</p> |
