Unrepeatered Systems: A View of the Sea

By Anders Ljung and Rebecca Spence
July 21, 2021 

Unrepeatered cables form an important part of submarine connectivity, but have largely gone unscrutinised by the industry, mostly due to their simple design and distance limitations. Unrepeatered links were the original ‘Open Systems’ owing mainly to their passive nature, and they are often procured in a disaggregated manner largely due to the simplicity of their line design. They are used for different purposes in several markets. For pure telecoms, they typically form short point-to-point systems between neighbouring countries, regions and islands. They can add expand links to international connectivity by joining onto transoceanic systems at their landing points, and they are typically used to cross harbours, rivers and lakes.

Unrepeatered links are also used to provide connectivity to and between oil platforms, offshore wind farms and ocean observatories. They provide a telecoms path to power systems, either as an integral package or an outrider cable.  Unrepeatered systems do away with the need for power feeding equipment, repeaters and line monitoring equipment, making them attractive for parts of the world where resources are limited, or locations where high -power equipment may not be desirable, such as oil platforms.  We believe the role they play in both regional subsea connectivity and supporting telecoms infrastructure within sister networks such as oil & gas, renewables and power cables is too significant to go undiscussed.  There will always be a requirement for short hop connectivity and the advantages it offers in terms of cost, timescales and complexity.

Earlier this year, SubTel Forum carried out a review of unrepeatered activity across the globe. The difficulty with studying this subject is that the majority of unrepeatered systems go unannounced, in particular those which support oil & gas networks and power cables. Many contract awards are directed and every supplier will not receive every tender.  Based on Hexatronic internal sales data and an analysis of the market share of each of the cable suppliers, we estimate that the ratio of announced to installed systems is around 1:5. The information reported below is based solely on publicly announced telecommunications cable systems, and those that Hexatronic have specifically been involved with. We have tried to indicate where we believe the numbers are skewed by lack of available data and which trends we believe are valid and which we do not.

Based on publicly announced projects for the period between 2016 to 2020, there were a total of 97 unrepeatered systems put into service during this time, see Figure 2 below. We at Hexatronic estimate that a further ?400 unrepeatered links were installed globally during this five-year period.

To continue reading the rest of this article, please read it in Issue 119 of the SubTel Forum Magazine on page 18 or on our archive site here.