Forward error correction in a 5 Gbit/s 6400 km EDFA based system

For the first time, forward error correction (FEC) was used to improve the performance of a 5 Gbit/s 6400 km erbium doped fibre amplifier based system. The performance of a transoceanic optically amplified system can be significantly improved by using FEC. The Q required to achieve satisfactory performance is at least 5dB less than that without FEC. This additional margin could also be used to relax system specifications such as repeater spacing. As an example, the repeater spacing of a transoceanic system could be increased by more than 20% with no degradation in transmission performance with the use of FEC. The system robustness to degradation is also strongly enhanced by using FEC