| 摘要 |
PURPOSE: To quickly synchronize a frame, even before completing reception of the frame by detecting a periodical frame synchronizing word and reading a prescribed pointer from the frame to search a cell header. CONSTITUTION: For a frame, one octet consists of 270 columns and 9 rows. 9×9 octets are a section overhead SOH, and 261×9 octets are especially for payload. The first column of SOH includes a synchronizing word SYMC. Payload includes a container C4 capable of transmitting an ATM cell. The ATM cell is synchronized, and a cell header is decoded to discriminate the payload. A bus overhead and the container C4 form a virtual container VC4. In synchronization, one synchronizing word is detected in a hunt mode, and a pointer AU-4 addressing a data area VC4 of the cell constitution is read at a prescribed distance apart from this word. Next, the header of the ATM cell in the data area designated by the pointer is decoded, and the state is switched to the synchronous state, when X number of correct cell headers are decoded in succession. |
