FEATURE
SUBSEA TELECOMMUNICATIONS CABLES The Critical Infrastructure Connecting Our World BY MARC KEBBEL
A
ccording to TeleGeography there are around 485 in-service telecommunications cable systems lying on or just below the seabed. Responsible for carrying more than 99 % of internet traffic between continents, these fragile subsea networks are the lifeblood of the global economy. We fail to protect them at our peril. Subsea cabling has moved on a long way since 1850, when it was first laid in the English Channel to transmit telegraph signals between England and France. Today there is an increasingly intricate spiderweb of subsea telecommunications cables around the globe. This surprisingly vulnerable network carries nearly all intercontinental electronic communications traffic. It therefore plays a critical role in the day-to-day running of businesses and public services the world over.
information (including video) equivalent to 150 million simultaneous phone calls. Subsea telecommunications cables used to contain between two and eight pairs of fibres. However, given the exponential rise in data traffic and the need for speed, cable owners are now looking for new ways to increase the number of fibres in each bundle without reducing transmission efficiency. A recently laid transatlantic cable has squeezed in a record-breaking 24 pairs of fibres, enabling the transmission of vast quantities of data at astonishing speeds of up to 500 terabytes a second. The latest trend is Spatial Division Multiplexing – a disruptive design approach that aims to optimise the cost per byte and boost capacity by up to 70 %.
WHAT LIES BENEATH
Despite the huge cost of installing subsea telecommunications cables – between $200 million and $2 billion, depending on the design and length of the system – they continue to proliferate around the globe in an attempt to satisfy our insatiable appetite for data. The data they transport has transformed individuals,
Today’s subsea communications cables use optical fibres, each as thin as a single strand of human hair and sheathed in protective insulating layers, to transmit telephone and internet signals. According to the International Cable Protection Committee, a single fibre pair can carry digitised
THE CHALLENGES
SEPTEMBER 2023 | ISSUE 132 45