ITU-T's Study Group 15 has agreed on design guidelines for optical fibre submarine cable systems.
Submarine cable systems form a very important part of the world's ICT
network infrastructure with cables linking all the world's continents
except Antarctica. And as demand for increased transmission capacity
increases, owners of these networks are keen to optimize their
investments, because laying new submarine cables is an expensive and
The guidelines appear in a supplement to ITU-T Recommendations on the
topic of submarine cable systems (Supplement 41, to the G series of
ITU-T Recommendations), and allow for the incorporation of traditional
technology (e.g. WDM systems, erbium doped fibre amplifiers) as well as
new technology including new generation forward error correction (FEC)
and Raman amplifiers.
According to the expert authors, the document has been produced with a
key objective to detail the main technical issues to be taken into
account in order to achieve a link's longest distance, with maximum
The supplement describes considerations for repeatered, repeaterless
and optically amplified systems supporting synchronous digital
hierarchy (SDH) and optical transport network (OTN) signals.
Repeaterless submarine cable systems are used for terrestrial network
extensions in cases where submarine distances up to about 350 km are to
be covered. Repeatered submarine systems are used for long haul, large
capacity transmission by using submerged optical amplifiers in order to
cross distances up to transoceanic lengths.