Downstream data frame transmission method and device

A downstream data frame receiving method for a passive optical network (PON) system, the method comprising:

• determining, by an optical network unit (ONU) based on a physical synchronization sequence (Psync) field of a downstream data frame, whether to enter a synchronization state, wherein the downstream data frame comprises a frame header and a payload, the frame header comprises the Psync field, and the Psync field identifies the downstream data frame, wherein the Psync field comprises multiple bits for indicating whether or not payload data is protected by forward error correction (FEC);
• and
• based on the ONU entering the synchronization state, determining, by the ONU based on the Psync field of the downstream data frame, whether to decode the payload data;
• wherein a first value of the Psync field corresponds to the payload being protected by FEC, a second value of the Psync field corresponds to the payload not being protected by FEC, and a Hamming distance between the first value and the second value is as large as possible.

An optical line terminal (OLT) of a passive optical network (PON) system, the OLT comprising a processor and a non-transitory computer-readable medium having processor-executable instructions stored thereon, wherein the processor-executable instructions, when executed by the processor, facilitate:

• generating a downstream data frame, wherein the downstream data frame comprises a frame header and a payload, the frame header comprises a physical synchronization sequence (Psync) field, and the Psync field identifies the downstream data frame, wherein the Psync field comprises multiple bits for indicating whether or not payload data is protected by forward error correction (FEC);
• and
• sending the downstream data frame;
• wherein a first value of the Psync field corresponds to the payload being protected by FEC, a second value of the Psync field corresponds to the payload not being protected by FEC, and a Hamming distance between the first value and the second value is as large as possible.

An optical network unit (ONU) for a passive optical network (PON) system, the ONU comprising a processor and a non-transitory computer-readable medium having processor-executable instructions stored thereon, wherein the processor-executable instructions, when executed by the processor, facilitate:

• determining, based on a physical synchronization sequence (Psync) field of a downstream data frame, whether the ONU enters a synchronization state, wherein the downstream data frame comprises a frame header and a payload, the frame header comprises the Psync field, and the Psync field identifies the downstream data frame, wherein the Psync field comprises multiple bits for indicating whether or not payload data is protected by forward error correction (FEC);
• and
• determining, based on the Psync field of the downstream data frame, whether to decode the payload data;
• wherein a first value of the Psync field corresponds to the payload being protected by FEC, a second value of the Psync field corresponds to the payload not being protected by FEC, and a Hamming distance between the first value and the second value is as large as possible.