| 摘要 |
An optical line terminal (OLT) controls one or more optical network units (ONUs, not shown) connected thereto. An upstream cell termination unit (66) receives messages from the ONUs. A message code detector (52-<WC 1>1 n) extracts valid messages from among the messages received by the upstream cell termination unit, through a process of filtering out such messages that indicate that the se<WC 1>nding ONUs have no information to send. A cell extraction unit (51-1 n) identifies <WC 1>the sending ONUs which are sourcing the valid messages extracted by the message code detector. A PLOAM grant generator (6e-1 n) produces message transm<WC 1>iss<WC 1>ion permissions (i.e., PLOAM grants) which permit the sending ONUs identified by the cell extraction unit to transmit messages (i.e., PLOAM cells). The message transmission permissions <WC 1><WC 1>produced by the PLOAM grant generator are then transmitted to the ONU through a PLOAM cell transmitter. The proposed OLT can receive messages from a plurality of ONUs more reliably, because of its capability of allocating message transmission permissions to the ONUs depending on their individual conditions. |
