Jin-Xing Transmission Cai, … Neil S. Bergano, in Fiber Optic Telecommunications VII, 2020
13.2. 3.1 Adjustment Speed Error To Correct iya
Which are forward error correcting code?
Forward Error Punishment (FEC) is the process of adding redundant data, such as the actual error correction code (ECC), to the target so that the recipient can correct it, even though the actual number of errors (usually up to one – the capacity of the time code) were introduced either during transmission or during storage.
Using multiple FECs with different FEC thresholds in a WDM system may consume more resources than using a specific FEC. Reference friends and family  developed 52 spatially related LDPC codes and thus explored the use of many different FEC numbers. The throughput increase associated with using 8 FECs (with admiration for one FEC, both without NLC) is between 15.5% and 21% for a transmission distance of 10,200 times per 6000 km. A further increase in the choice of FECs used does not lead to a significantly larger increase in capacity, as shown in Fig. 13.24. The disadvantage of this scheme is that the implementation of FEC increases the penalty for a stronger FEC code. For example, the implementation cost increases by 0.5 to > 1 dB when the FEC code rate is initially increased from 0.87 to 0.52.
Figure 13.24. Net Capacity Added and Forward Error Penalties (FEC), ©  IEEE. Reproduced with permission, , par.