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Using Innovative Optical Fibre to Build Access Networks in Africa

20 May, 2013
ICT Africa Writer
May 20, 2013

It is imperative that as African telecommunication operators continue to build telecommunication networks to improve connectivity and the lives of Africans, they leapfrog obsolete technologies that were used in the past and have no place in modern networks. From time to time we will share innovative new technologies that could make a significant impact on the development of modern ICTs in Africa. This week, we examine a new optical fibre developed by Corning Incorporated – the pioneer and the world’s largest supplier of optical fibre.

In a recent article, we pointed out that while mobile broadband networks will cost effectively and expediently bring broadband to more Africans, wire-line access networks should also be developed alongside mobile networks for higher bandwidth applications. For operators and service providers who do not already have a copper footprint, the wire-line network of choice should be Fibre-To-The Home (FTTH). The notion that building copper networks is cheaper than building fibre optic networks is erroneous because the bulk of the cost of developing wire-line networks is in the civil works and whatever cost difference exists between copper and fibre optic cable is irrelevant. Moreover, the long term cost of operating a fibre optic network is lower than that of operating a copper network, making the overall cost of ownership for a fibre optic network lower.

A number of African operators, including Twenty First Century in Nigeria, Algerie Telecom, Telkom South Africa, JAMII in Kenya, Access Kenya and many others understand this and are either deploying or planning to deploy FTTH networks. But like any other technologies, FTTH has a few challenges that can be solved by using innovative new technologies.

While optical fibre can transmit signals to distances that are hundreds of times further than copper for any given bandwidth, signals transmitted through optical fibre also experience loss that will ultimately limit the transmission distance. In the International Telecommunication standard (ITU-T G987) for the transmission of 10Gb/s in a Passive Optical Network (XGPON1), the distance between the Optical Line Terminal (OLT) and the network access point is specified as 20km. This means that using standard optical fibre, you cannot cover customers who are located within a radius of 20km beyond the central office.

Furthermore, one downside of standard single mode fibre is that when it is bent, it loses some of the laser light carrying the signal. The tighter the bend, the more light is lost and the more the signal is degraded. In 2007, ITU came up with a new standard (ITU-T G.657) for optical fibre that can be bent without losing too much light. The standard has three levels of bend performance; A1 or bend improved, A2 /B2 or bend intolerant and B3 or bend insensitive fibre.

Typically, operators building FTTH networks use a standard single mode fibre compliant with the ITU-T G.652D standard from the central office to the network access point, G.675A1 or G.675A2/B2 fibre from the network access point to the building where fibre can experience moderate bends. Inside the building where fibre is prone to experience tight bends, G.657B3 fibre is typically used.

In a new product called SMF-28e® Ultra fibre, Corning has included better bend performance, complying with the G.657A1 standard, on their low loss optical fibre, SMF-28e+®LL fibre. This means that in addition to extending the 20km distance limit in the ITU-T G.987 or similar standard, the fibre can be used anywhere in the outside plant of an FTTH network. Instead of using one fibre from OLP to network access point and another from the access network point to the building, network designers can now use one fibre. Moreover, due to its backward compatibility with G.652D fibre, the fibre can also be used in any terrestrial long haul or metropolitan networks.

For more information on this innovation, you can join Corning’s Free Webinar


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