There is no plan B for submarine networks, the “jugular veins” of international connectivity. That is how integral they are to telecommunications, according to Brian Lavallée, senior director of submarine network solutions at Ciena.
“This fact means that submarine networking technologies will (and must) continue to rapidly evolve, out of sheer necessity, just to maintain pace with our voracious appetite for content and applications in a highly reliable manner,” Lavallée says.
Yet despite the profound impact subsea cables have on the world, misconceptions around them remain prevalent. The general public, Lavallée says, tends to think they are connected to a satellite network, but that is rarely the case.
“It isn’t satellite networks – that’s more for small island nations, and a lot of people get confused with that,” he says.
Submarine networks carry more than 99% of the world’s intercontinental electronic communications traffic and every day around US$15 trillion worth of transactions travel along them.
“So, without them, there is no global internet,” explains Lavallée.
Lavallée has been in the submarine space for around 10 years and boasts a total of 20 years in the wider telecoms industry.
Lavallée says he entered the submarine cable sector because, “It touches upon two areas that I love: one being telecommunications and the other being the oceans, so putting those things together was very appealing to me.”
Waves of change
The submarine networking industry has undergone several technological changes, including the rapid adoption of coherent modems originally developed for long-haul terrestrial networks. These devices changed how much capacity could be added to transoceanic corridors, extending the life of existing wet plant assets, and opened existing and new wet plants to bed-of-breed upgrade vendors, completely changing legacy business models and associated economics.
The roll out of this technology was a key step in uniting land, sea and cloud networks, and it has enabled subsea networks to keep up with growing bandwidth demands. Submarine operators are now able to mix and match network building blocks to create purpose-built end-to-end solutions.
“Just over 10 years ago, we invented coherent networks, and initially it was designed for long-haul terrestrial use,” Lavallée says. “But we tested it over submarine cables and the proverbial lightbulb went off, and were able to increase channel rates from 10Gbps to 40Gbps, and then 100Gbps and then to multiple hundreds of gigabits-per-second.”
Lavallée says that this realisation meant there was enough link margin available to allow cables to go all the way inland, meaning terminals could be moved from beaches to point-of-presence and central offices.
Ciena was able to replace optical switching in a landing station with an all-optical modem. This resulted in a decrease in power space and equipment complexity.
“Now it is typically moved into the data centre, and that simplification and massive increase in scalability came with reduced power, space costs and even latency, was a huge benefit to cable operators, and we’ve never looked back,” Lavallée explains. “This is the way most vendors are now building out their submarine networks, but we pioneered that.”
This is where Ciena’s GeoMesh solution came in. It allowed the company to merge submarine and terrestrial cables into a single end-to-end network. And now, Lavallée says, the company is integrating cloud networks into that converged network.
Subsea’s future
In 1948, US engineer Claude Shannon wrote a paper showing that communications and fibre optic-based subsea cables are characterised by bandwidth and noise.
In his paper, Shannon, who is known as the “Father of Information Theory”, showed how to calculate channel capacity: the maximum data rate a cable could deliver before incurring transmission errors.
Future advances in silicon technology are expected to push the performance of cables towards this limit, which is called the “Shannon limit” in the subsea industry – the maximum rate of error-free data that can be theoretically transferred over the channel if the link is subject to random data transmission errors.
“We’re getting really close to Shannon. We’d like to say we’re knocking on Shannon’s door,” Lavallée says. “We’re getting as close as we can with incremental upgrades, particularly in comparison to the first generation of mobile technology where we made massive increases.”
But these increases Ciena achieves are now getting smaller and smaller as technology approaches the Shannon Limit. Currently, the only way to increase the capacity of a cable is to add more fibre pairs. And according to Lavallée, that is what is happening.
“So, the industry saw this and decided that instead of putting four to six fibre pairs, it’d begin putting in 16 fibre pairs. And now there’s even talk of 24 fibre pairs, and that represents a massive increase in total capacity,” says Lavallée.
This is possible by using spatial division multiplexing (SDM), which is based on multiple-input multiple-output (MIMO) technology, which enables antennae, transmitters and receivers to simultaneously carry multiple data streams within the same frequency band.
The first in-service undersea cable featuring a 12 fibre-pair SDM design was Google’s 6,600km-long Dunant submarine cable system that connects Virginia Beach in the United States to the French Atlantic coast.
Traditionally, “wet plant” refers to subsea components that have to be managed like those that are above water, and are laid using ships specifically modified for that purpose. For instance, a special plough is used to bury these cables in the seabed close to the shorelines to prevent them being damaged.
According to Lavallée, this kind of infrastructure is usually designed to have a 25-year lifespan. This does not mean that subsea cables cannot last longer, but components at the bottom of an ocean are difficult to reach and manage.
The key to the future of subsea connectivity will be dwarfing what came before, and, naturally, with the progression of technology, this will be inevitable.
“So that 25-year number still seems to be the one that the industry is defined by, but I think, economically, they fall out of favour before they start failing,” Lavallée says.
As a result, Lavallée believes that in the near future there will be more consortiums coming together to lay more subsea cables.
This is particularly likely as the hyperscalers – Facebook, Google, Microsoft and Amazon, and their peers – continue to invest in subsea projects, both as part of consortiums and through their own projects.
“There are other regions in the world where they don’t have separate cable connectivity, so they have to use wholesalers, whether it’s a single owner or whether it’s a consortium,” Lavallée says.
Moving forward, Lavallée believes that transatlantic countries have seen the highest traffic for many years, but looking at new wet plant investments, the transpacific region presents opportunities aplenty.
Lavallée also believes Africa will see a lot of submarine cables landing around the continent, beginning with the 2Africa cable, one of the largest subsea projects in the world, which is due to go live by 2024.
Ciena itself is working with the West Indian Ocean Cable Company (WIOCC) on fibre running from Portugal along Africa’s coast. These plans, which include activating a fibre pair on the Equiano and the 2Africa cables, aim to connect open-access data centres between Lagos, Nigeria, and Rondebosch, South Africa.
Innovation
On the wet plant side, Lavallée says that submarine branching units that will allow cables to be split and so serve more than one destination are something to look out for. This development would allow one branch of a cable to run to a landing point, while the rest continue to different destinations.
“In the past, a cable was passive, meaning a wavelength would be redirected to a branch site and we couldn’t do anything about it,” says Lavallée. “But now we’re making it active, kind of like a road underwater.”
When it comes to developments on the software side, Lavallée points to automation, machine learning and artificial intelligence.
One area Lavallée believes future software will open up is “preventative maintenance”, by enabling cable operators to “start to detect failures before they occur and address them”.
Lavallée says there are plenty of other advancements to come in the subsea cable space, particularly around sustainability, software automation and control.
“Once all that stuff comes together, it becomes incredibly complex to control and reroute services, so software control and automation will be a much bigger part of networks going forward,” he predicts. “They’re not going to be big fat capacity pipes – they’re going to be much smarter.”
