GPON 帧结构培训.pptxVIP

GTC layer Framing ;GTC layer framing See clause 8/G.984.3 (2008) ;DS Data Transmission (TDM);US Data Transmission (TDMA);1.24416 Gbit/s , 19440 bytes 2.48832 Gbit/s, 38880 bytes;;;Psync field (Physical synchronization) This 4-byte pattern is used to find the beginning of the frame. The coding of the PSync field is 0xB6AB31E0;IDENT field The 4-byte IDENT field is to indicate larger framing structures ;PLOAMd field 13-bytes field contains the PLOAM message BIP field 1-byte field is used to measure the error in the downstream Plend field Specifies the length of the Bandwidth map and the deprecated ATM partition;BWmap fields Alloc-ID 0~253, carry PLOAM and OMCI traffic; 254, activation Alloc-ID; 255, unassigned Alloc-ID; 256~4095; Flag fields - Bit 11 (SMB): Send PLSu (power levelling sequence); - Bit 10: Send PLOAMu; - Bit 9: Use FEC; - Bits 8 and 7: Send DBRu (mode) 00: Do not send DBRu at all 01: Send the mode 0 DBRu (two bytes). 10: Send the mode 1 DBRu (three bytes). - Bits 6-0: reserved;Serial number request Alloc-ID?=?254, PLOAMu?=?’1’, StartTime = xx, StopTime = xx + 12 Ranging request Alloc-ID? = ONU-ID, PLOAMu=’1’, StartTime = xx, StopTime = xx + 12;PLI: indicates the length L, in bytes, of the payload following this header, 4095 bytes Port-ID: provide 4096 unique traffic identifiers on the PON PTI: indicate the content type of the payload and its appropriate treatm HEC: provides error detection and correction functions for the header;A user data fragment cannot straddle a GTC frame boundary. The purpose of fragmentation - To insert a GEM header at the beginning of each GTC payload - The time sensitive data must pre-empt the transmission of non-time sensitive traffic;GPON US Framing;Upstream burst structure;Physical layer overhead upstream (PLOu) preamble and delimiter; BIP field ; ONU-ID field; Ind field; ;PLOAM upstream (PLOAMu) Contains