Downstream data frame transmission method and device

A downstream data frame receiving method, wherein the method is applied to a passive optical network (PON) system and comprises:

• 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 is used to identify the downstream data frame, wherein when a value of the Psync field is a first value, the Psync field is further used to indicate that payload data is protected by forward error correction (FEC);
• or when a value of the Psync field is a second value, the Psync field is further used to indicate that payload data is not protected by FEC;
• and
• if the ONU enters the synchronization state, determining, by the ONU based on the Psync field of the downstream data frame, whether to decode the payload data.

An OLT, wherein the OLT is applied to a passive optical network (PON) system and comprises a framer and a transmitter, wherein

• the framer is configured to:
• generate a downstream data frame and send the downstream data frame to the transmitter, 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 is used to identify the downstream data frame, wherein when a value of the Psync field is a first value, the Psync field is further used to indicate that payload data is protected by forward error correction (FEC);
• or when a value of the Psync field is a second value, the Psync field is further used to indicate that payload data is not protected by FEC;
• and
• the transmitter is configured to:
• receive the downstream data frame from the framer and send the downstream data frame.

An ONU, wherein the ONU is applied to a passive optical network (PON) system and comprises a synchronous state machine and a determiner, wherein

• the synchronous state machine is configured to determine, based on a physical synchronization sequence (Psync) field of a downstream data frame, whether the ONU enters a synchronization state, and if the ONU enters the synchronization state, sends the downstream data frame to the determiner, wherein the downstream data frame comprises a frame header and a payload, the frame header comprises the Psync field, and the Psync field is used to identify the downstream data frame, wherein when a value of the Psync field is a first value, the Psync field is further used to indicate that payload data is protected by forward error correction (FEC);
• or when a value of the Psync field is a second value, the Psync field is further used to indicate that payload data is not protected by FEC;
• and
• the determiner is configured to:
• receive the downstream data frame from the synchronous state machine, and determine, based on the Psync field of the downstream data frame, whether to decode the payload data.