This Recommendation is concerned primarily with the system performance and interface requirements of repeaterless optical fibre submarine cable systems; it considers both single wavelength systems (SWS), wavelength division multiplexing systems (WDMS) and dense wavelength division multiplexing systems (DWDMS). It also covers the aspects related to the applications of discrete optical fibre amplifiers (OFAs) as power amplifiers, pre-amplifiers and/or remote optically pumped amplifiers (ROPA) (either erbium-doped transmission fibres using remote pumping from the terminal or the distributed Raman amplification pumped from the terminal).

The purpose of a repeaterless optical fibre submarine cable system is to establish transmission links between two or more terminal stations located in a restricted geographical area.

A cable system connecting only two terminal stations may be termed an "optical fibre submarine cable link". When it connects more than two terminal stations, it may be termed an "optical fibre submarine cable network".

In a repeaterless submarine cable system, no power feeding equipment (PFE) is necessary as there is no in-line OFA.

As far as the branching unit devices are concerned, those considered in this Recommendation are the passive ones, therefore avoiding electronic components and supervisory and power feeding.

Common implementation aspects of optical submarine cable systems for manufacturing, installing and maintenance are described in [ITU-T G.971]. [ITU-T G.978] contains common aspects of the characteristics of the optical fibre submarine cables. [ITU-T G.979] is also concerned with the characteristics of monitoring systems for repeaterless optical fibre submarine cable systems.

The physical implementation of repeaterless optical fibre submarine cable systems and the implications of the use of ROPA are considered respectively in Annexes A and B.