scope:

This Recommendation describes the Forward Error Correction (FEC) functions that have higher-correction ability than RS(255,239) code defined in ITU-T Rec. G.975 in the optical fibre submarine cable systems. This Recommendation also describes the system requirement concerning supervision for the submarine cable systems. The applications being addressed in this Recommendation are both optically amplified repeatered systems (ITU-T Rec. G.977) and repeaterless optical systems (ITU-T Rec. G.973). The use of this FEC function in submarine terminal transmission equipments (TTEs) should not be considered as mandatory.

It is not the intention of this Recommendation to pursue the transverse compatibility of the system. Therefore, the selection of the FEC frame structures described in this Recommendation is a matter of joint engineering.

The transmission signal under consideration could be STM-16, STM-64, STM-256, ODU1, ODU2, and ODU3, because submarine systems could be considered as one of the IaDI applications defined in ITU-T Rec. G.872. This does not mean that the bit rate is restricted within the above-mentioned signals. 2