Patent ID: 8402339

Claim:
An error correcting device in an optical communication system that transmits a transmission frame formed by adding an overhead and an error correction code to information data, the error correcting device comprising: an outer-code forward error correction (FEC)-coding unit that performs FEC coding with an outer code for the transmission frame by using a concatenated code or an iterated code of at least two error correction codes as the outer code, and partitions columns of a first FEC redundant area in an optical channel transport unit-k (OTUk) frame having N rows included in the transmission frame into at least two portions each having N rows to store therein information indicating the at least two error correction codes as the outer code, respectively; an inner-code FEC-coding unit that performs FEC coding with an inner code for the transmission frame by using an error correction code for soft-decision decoding as the inner code, and additionally provides a second FEC redundant area having N rows and being adjacent to the first FEC redundant area for the inner code in the OTUk frame to store therein the error correction code for soft-decision decoding of the inner code; an inner-code FEC-decoding unit that performs soft-decision FEC decoding with the inner code for a transmission frame received; and an outer-code FEC-decoding unit that performs hard-decision FEC decoding with the outer code for the transmission frame subjected to the soft-decision FEC decoding by the inner-code FEC-decoding unit.