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Making a deep impact

Keely Portway looks at the latest developments in submarine networks, and the issues and trends shaping the market

The submarine cable industry is reportedly booming, with latest figures from Research and Markets putting the global market at $10.3bn in 2017 – with it expected to rise to $30.8bn by 2026. 
Some of the driving factors, according to the report, The Submarine Cable System – Global Market Outlook (2017-2026), include the increasing need for network capabilities, the growing number of telecom subscriptions and rising internet traffic. There are also a number of new geographical opportunities presenting themselves, with Africa of particular note. 
Recently Google announced its investment in this market, with a private subsea cable that will connect Africa with Europe. Once complete, Equiano will start in western Europe and run along Africa’s west coast, from Portugal to South Africa, with branching units that can extend connectivity to additional African countries. The first is expected to land in Nigeria. The cable is funded by Google, making it the firm’s third private international cable after Dunant and Curie, and its 14th subsea cable investment.
Into Africa 
According to Ian Clarke, VP of global submarine solutions at network strategy and technology company, Ciena, which supplies transmission equipment into subsea networks, this is just the beginning. ‘Africa is the hotbed of many discussions. From the Googles and the Facebooks of this world, there are markers for success and there are certain countries that have got many eyeballs that remain unconnected. They are very keen to go and attract those areas. There’s a huge amount of industry chat about “how do we connect to Africa?”’ 
Built in conjunction with Alcatel Submarine Networks, Equiano will operate differently than traditional cables. Instead of wavelength-level switching, it will incorporate optical switching at the fibre-pair level. This simplifies the allocation of cable capacity, allowing the flexibility to add and reallocate it in different locations as needed. The first phase of the project, connecting South Africa with Portugal, is expected to be completed in 2021. 
This manner of operation looks set to shape the submarine networks landscape, Clarke explained: ‘We are now seeing new cables being built with a different technology that carries more traffic. One obvious scenario is the emergence of spatial division multiplexing (SDM). It’s putting more fibres in a cable. Around four years ago, you had eight fibre pairs on a cable. People asked: “Why have you only got eight?” Well, when you put the amplifiers on the sea bed you’ve got to put them all in on day one. When putting amplifiers every 50 to 60km across the ocean, it was very expensive to go and equip multiple fibre pairs and power them that you might not need for a certain amount of time, so we stayed at between four and eight fibre pairs. But now we can put in more fibres, for the total capacity of the cable. We’re changing our design, per fibre pair to be lower, but the total of passes to be higher.’ 
High time 
SubCom has acted as an undersea data transport partner for a number of networks, including the Google-funded Curie cable, which links Chile and California. Georg Mohs, VP R&D and CTO agrees that technology is changing with the drive for higher capacity. ‘We see a sustained and continued drive for more capacity in undersea systems,’ he said. ‘There are a number of advances that we’re taking advantage of, in order to drive this higher capacity on the cables, like SDM. What we see is a drive to increase capacity on the cable and we’re moving away from maximising the capacity per fibre pair, rather maximising the capacity for fibre on the cable. 
‘One of the enablers for that is by making smarter use of the pump power that’s available. The pump power is what feasibly drives the amplifiers, the repeaters in the system. So, we’re making use of this more efficiently by splitting it onto multiple fibre pairs. Therefore, we get a little bit less capacity per fibre pair, but now we have more fibre pairs and therefore also the capacity on the cable increases and improves.’ 
This shift in technology, believes Mohs, is changing the way cables are built. ‘It’s driving more fibre pairs from the cable and more amplifiers in the repeaters,’ he said, ‘so there’s a drive towards almost an explosion, in terms of the number of fibre pairs. 
‘The systems in the past have been around six, maybe eight sets of fibre pairs and now we’re seeing demand for systems that are 12 fibre pairs, with the expectation to go even higher. 
‘These other technologies we’re using are optical add-drop multiplexing (OADM) based, so we’re deploying fully a reconfigurable optical add-drop multiplexer (ROADM). It’s a known technology in terrestrial systems, but just making its way into under-sea systems now, and providing more flexibility in terms of traffic routing over the life of the system. We’re also starting to implement optical switches in undersea systems where you can now get more complex switch matrices. There’s no longer just a bypass switch, you can decide which fibre pair to drop onto a branch, to a switch matrix in branching nodes. There are a lot of technology advances happening to support these higher fibre-count systems, where we’re basically making cables with a count up to 24 or even 32-fibre.’ 
Supply and demand 
The company has further optimised its production processes to enable these higher fibre-counts and for its repeaters to increase the density of amplifiers. ‘There’s a challenge associated with that,’ Mohs said, ‘to fit more components and treat the higher density and the repeaters. It’s an evolution of the product line. It’s not really radically different, but we’re evolving the product to accommodate these higher fibre counts. We’re the supplier, so we’re meeting the demand.’ 
Clarke concurs on the technological evolution. ‘In terrestrial land, we’ve had ROADMs for 20 years,’ he said. ‘But only just now we’re starting to put ROADMs on the sea bed.’ This, he said, is because of the concern of what might happen if it goes wrong, but also because it takes longer to qualify the components for an extra period of time. ‘While there is a reactive environment on the terrestrial land, it’s very much slower and more methodical in subsea,’ he said. ‘So, we’re reluctant to change. But the change in our eco-system, the ideas of the tier one carriers of this world being superseded by the content providers who, if you look at the tele-geographies, certainly show that most of the traffic is content driven. Then, just our consumer experience, moving from voice to VoIP in terms of WhatsApp and Facetime and Facebook live, every possible thing is driven to require a completely different network.’ 
Centre stage 
The other big change affecting submarine networks, highlights Clarke, is building into data centres, rather than cities. ‘[Instead] of going New York to London, which all of the North Atlantic cables used to go to because they were the VoIP centres. Now we’re going to data centres like Virginia Beach, or to Dublin, because that’s where they’re building data centres. Once the data centre location has been picked, people try to work out how to get a cable there because it has to be connected. We’ve been driven to change because of our eco system around us. Wherever you look, there’s a data centre being built. You can track where they are and as they get announced, they will clearly have to be connected. That’s a key indicator. Look at the data centres and then know that in some way, shape or form, there’s a cable to be announced.’ 
For Mohs, another trend worth mentioning is coherent transmission. ‘We have extended the reach of trans-oceanic systems, now we are really creating systems and connecting Hong Kong to the west coast of the US directly. These are longer than 10,000km, more or less, and are being enabled by coherent technology. This is a little bit older, but certainly a difference in the trend that we’ve seen before. There is a drive for longer systems now and not only US-Japan. We’re going to Hong Kong now and even further than that.’ 
This provides its own set of challenges, Mohs explained. ‘You try to support more and more capacity on the cable, and in order to have more capacity, you have to have a better signal to noise ratio. This means you need a better signal, and you need more power. We can only provide the power from the ends of the cable, as there are no outlets along the ocean floor. So, the longer you make the cable, the more challenging it becomes to power all that additional capacity.’ 
The future 
Looking at how the industry will evolve going forward, Mohs sees no sign of the drive for higher capacity abating. ‘With all the technologies that are coming online, with virtual reality, augmented reality all those things that drive the bandwidth, drive capacity, drive low latency... the really low latency applications are well suited for undersea cables,’ he said. ‘I don’t think we’re going to plateau. We’re certainly, from a technology perspective, going to continue to drive higher capacity.’ 
‘If you look forward the next three years,’ agreed Clarke, ‘we’re looking at somewhere in the order of 50 or so cables being built. Our deployment engines – the companies we talk to right at the start – are going as fast as they can, using as many as they can, trying to contract and then lobby together cables ordered in the manufacturing cycle and then deployed. Our industry is going really quick and updating cables, building new capacities. That would still be dealing with the same style of build a cable, put systems on it and away we go.’ 
What we are starting to see, said Clarke, is the ‘absolute evolution of AI.’ He explained: ‘AI is a word that is used a lot. It’s the word that everybody gravitates to and sometimes I wonder if people know what we mean by AI in the submarine community. AI is a branch of computer science that tries to simulate a type of human behaviour. How do you define intelligent human behaviour? Based on senses and experience, and computer power to process those senses and experiences.’ 
Continued Clarke: ‘In terms of subsea, if we have network sensors, which we do, everywhere – whether it be loss of signal, error rate, chromatic dispersion, latency – if you could get all of that information and then you could analyse it, pull it into a machine learning environment and react upon that, that is AI in submarine. It’s really the ability to apply machine learning in our environment.’ 
Automatic pilot 
But, asks Clarke, what is it that machine learning brings to the submarine environment? ‘Quite simply,’ he said, ‘you design a system for 25 years of life so we have to apply physical optical margins to our systems that say OK, the cable is going to age. It might have X number of physical breaks and there’s a standard that says in deep water you must apply this-many-breaks per-year-per-kilometre. There are parameters. And then the equipment will age as well. So, you leave a certain amount of optical margin on that cable at any one time. Somebody may turn around and ask “what if I can channel a set rate above the X point and then let the channel automatically adapt at the cable edge, so there is not a big margin at the start that is wasted because it is designed for 25 years later?” 
ʻAll the cards that we use today have the ability to change the bit rate. So, why don’t we make them intelligent? Also, if your cable breaks or fails and it’s a deep-water failure, it could take three weeks to get a cable shipped out there and fix it. A lot of people build four or five different routes if they can afford to have that. Some people can’t.’ 
The use of machine learning and other intelligent technology on submarine networks can help in negating downtime caused by damage or wear and tear. 
Clarke explained: ‘If it has a slow-burning fault, one that can be seen in erosion, if you could get that, and the machine monitored it and predicted the failure, it’s far easier to then re-route without the traffic being down. The restoration is more controlled because you are switching in a controlled environment, not a hard fail. The cost of doing that is usually cheaper. 
‘This ability to have pre-emptive failures where we maybe know there will be a fail, and there’s maybe about a month before we can restore the traffic elsewhere round that in our network. We can free up the cables, refer it in a controlled environment and then, whatever that fault may be, it is also a form of machine learning where we’ve learned the problem, and we’ve flowed the traffic around the problem, and we’ve executed a controlled network event. Pro-activeness. That’s what we are starting to see.’


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