Optical transmission system, optical transmission apparatus, and optical transmission method

An optical transmission apparatus comprising:

• an error correction coding unit configured to add an error correction code having a code length in accordance with transmission quality of each of sub-carriers forming a super channel to a main signal;
• an error correction code distribution unit configured to retrieve, from the error correction code added to the main signal on a sub-carrier to be processed, a code portion in excess of a predetermined redundancy level, and distribute the code portion to another sub-carrier;
• and
• an error correction code concatenating unit configured to concatenate the code portion of the error correction code to be added to a main signal on the another sub-carrier into the error correction code added to a main signal on the sub-carrier to be processed
• wherein the optical transmission apparatus transmits, through the super channel made up by the sub-carriers, the optical signal to which the main signal having the error correction code of the predetermined redundancy level is multiplexed.

A transmission method comprising:

• adding an error correction code having a code length in accordance with transmission quality of each of sub-carriers forming a super channel to a main signal;
• retrieving, from the error correction code added to the main signal on a sub-carrier to be processed, a code portion in excess of a predetermined redundancy level;
• distributing the code portion to another sub-carrier;
• concatenating the code portion of the error correction code to be added to a main signal on the another sub-carrier into the error correction code added to a main signal on the sub-carrier to be processed;
• and
• transmitting, through the super channel made up by the sub-carriers, an optical signal to which the main signal having the error correction code of the predetermined redundancy level is multiplexed.