Parallel FEC code in high-speed optical transmission systems

Parallel FEC code transmission is proposed, in which check bits are transmi tted on a different wavelength. The signal formal is perfectly compatible w ith SDH in terms of signal wavelength. A smooth upgrade to the FEC system i s possible by connecting additional modules. High FEC capability is obtaine d such that the BER of 10(-6) can be improved to 10(-11) with a decoding de lay of several bits. When the parallel processing number is 8, the GVD tole rance is extended by a factor of 2.5, while the number of L-REPs possible i n an optical link is doubled.