In the past, almost every form of long-distance communication was through intercontinental satellite. When the Internet first arrived, satellite links were quite common too. However, the high latency, low bandwidth and steep costs eventually resulted in satellite losing its position to fiber links. Now, satellites get used as backup or links for remote access. Almost 99 percent of the traffic moves via intercontinental links – which comprise six continents, with Antarctica being the only exception.
Transatlantic communication cables aren’t new. They were in use ever since the 19th century when a huge telegraph cable mesh linked the United States, Europe, Africa, Oceania and Asia – most coming under the aegis of the British Empire. During the period, copper wires were in use but there weren’t any repeaters. As a result, high voltage use was necessary on one side for registering a noisy and weak signal at the other end.
Submarine Cables
Despite being just 7 inches thick, submarine cables are quite resilient. Beneath the polystyrene layer, there is a mylar layer along with several steel cables, made for imparting mechanical resistance to the cable. There are also layers of polycarbonate and aluminium, which offer guaranteed water protection. A gel layer, copper tube, and a fiber bundle are also part of the package.
In addition to using high-quality fiber, the links also have solid-state optical repeaters, built into the cables at 100-km intervals. The repeaters relay the weak signal, letting the links extend across several thousand miles. The repeaters are energy-powered. The energy is sent through via the cables, making stations necessary only where packet routing or multiple-link integration has to be performed.
The cables, which cost several billion dollars, are placed above ocean floor along with specialized vessels. Work is performed in a couple of stages. The ship moves slowly and pushes the cable to the seabed. The ship is linked to a robotic installer that digs a small grave on the floor and buries the cable almost instantly. For proper signals, the installed cable should be perfectly straight.
At the moment, 40 gigabits can be transmitted for every strand. Every cable is made of several wires, which means the house’s total transmission capacity will be in terabits, as per the dark fiber’s specific percentage and cable Internet capacity.
These underwater cables are ably supported by regular land-based cables. These traditional cables are laid alongside power transmission lines or roads, making a fiber mesh spanning all big cities. Other access modes like cable, ADSL, 3G, etc. are fiber-connected, which helps create a large network base.
Inside the cables, the signal moves almost at lightning speeds. Good and reliable latency is possible even with router and repeater-induced delays. In fact, pings between Beijing and London are now under 300 ms – something that was beyond imagination some years ago.
Despite this, fresh cable internet are continuously installed, to reduce latency or increase current capacity. One of the recent examples is a new link connecting Japan and the UK, which passes via the Arctic Ocean, at an estimated cost of above $3 billion. The price covers the expense for cable, control station router installation, and related infrastructure.
