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Submarine salvage: a second life for old cables

Redeployment of old submarine fibre-optic cables can offer significant environmental and financial benefits, writes Bertrand Clesca


ore new submarine cable capacity was deployed last year than the entire undersea bandwidth in service globally in 2011, according to market

research firm TeleGeography. Tat astounding statistic represents international bandwidth growth of 44 per cent in 2014, to reach 211Tb/s. Wholesale carriers and private networks, particularly those of large content providers, continue to invest billions of dollars to upgrade the capacity of existing subsea cables and install new systems. In parallel to the demand for ultra-high-capacity

cables on the busiest international routes, there is a need to build new subsea connections to create physical route diversity and increased resiliency. One of the biggest challenges facing submarine network operators is that many parts of the world are still vulnerable to service disruption caused by natural disasters, such as mudslides and earthquakes. In the past decade a new trend has emerged. New

submarine routes are being installed to previously underserved areas, offering optical connectivity to small islands that did not previously have access to high-speed Internet services. Isolated island communities need to provide their inhabitants with reasonable communications services, which today play a crucial role in so many aspects of life, notably emergency services and administration, but also stimulating economic growth by supporting the flow of trade and information. Lack of access to international connections

prevents small communities from keeping up with the rest of the world. More generally speaking, it is widely recognised that economic growth is strongly linked to broadband access. In a study by Chalmers University for Ericsson, it was found that upgrading broadband speed to 4Mb/s increased household income between 2.2 and 4.7 per cent. In addition, broadband penetration has a direct correlation to a reduction in

20 FIBRE SYSTEMS Issue 9 • Autumn 2015

unemployment, according to a study for the International Telecommunications Union. Price and capacity-wise, satellite

communications are not in a position to meet these connectivity needs. Te last bastions of satellite dependency, including the land-locked countries in Africa and islands across the Pacific and Caribbean, are now discovering that their economic development needs will be better served by optical fibre. Switching from satellite to optical infrastructure is an effective way to increase the capacity, enhance the availability and reduce the latency of the network, improving both quality and stability of service. In recent years, Xtera has noticed an increasing number of projects that plan to extend optical

Lack of access to international connections prevents small communities from keeping up with the rest of the world

connectivity to small, remote islands. For example, there are ongoing discussions to find the best way to connect small island nations in the Pacific Ocean, populated by about less than 100,000 inhabitants each. New subsea systems for connecting small communities to the rest of the world do not require huge capacity but must offer a low price point to make the business case viable, bearing in mind the intrinsic small number of customers. Two options are available. One, build a new

subsea cable system, using components carefully selected to minimise the cost. Or two, recover and redeploy a subsea system that has been decommissioned, usually because the technology has become obsolete, leading to an unfavourable ratio between capacity and operational expenses on highly competitive submarine routes. In Xtera’s experience, building regional low-capacity systems on new routes represents the application where cable redeployment makes the most sense.

Low impact, high reward One of the major reasons for considering cable redeployment rather than new build is the lower overall project cost. Te typical cost structure of a new regional submarine cable system has a number of different elements (Figure 1). Te largest portions are the cable and repeaters (wet plant) and their assembly and transfer to the deployment location,


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