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Usage of fiber cables by enterprises have been increasing as there has been an upsurge in the bandwidth demand owing to the steady increase of data intensive applications and VoIP over the enterprise networks. However, conventional fiber is considered vulnerable for bending as there are inherent losses when we tend to bend these fibers during the deployment. This has resulted in fear psychosis among cabling integrators that deploying fiber cable is difficult compared to copper cables. This is one of the main reasons that it did not have a great uptake in the Indian market, though the story is quite opposite in the developed countries. Now, the question is that which innovation can make deploying fiber easy for enterprises? The solution lies in making fiber 'bend insensitive', so that the fiber will not be broken easily during the deployment. Bend insensitive fiber is more appropriately called 'less bend sensitive fiber', or 'bend resistant fiber', or 'bend optimized fiber', or 'bend improved fiber' to reflect the true nature of the technology.

Performance Companion
With the FTTx network rollouts proceeding across the world, the fiber to be installed is subject to a greater degree of bending, since smaller distribution cabinets and compact fiber management systems are deployed. ITU-T G 6567A offers an excellent macro bending performance. The bending limits of industry standard G.652.D fiber has been defined for 60 mm diameter, while the limits for G.657A has been defined for 20 mm and 30 mm diameters.

The essential difference between conventional fiber and bend intensive fiber is the allowable bending radia. While the conventional fiber starts deteriorating the transmission quality at radius 35 mm, the bend insensitive fibers have two classes-15 mm and 7 mm. Conventional fiber cables require a certain bend radius to be maintained while laying or using the fiber, and is kept as straight as possible. Most high-performance optical cables use a form of armor that resists tight bending. Any tighter coils or bends seriously affect the data transmission, thus affecting performance. On the other hand, it is required to lay and use the fiber in geometries, so the bend radius restriction becomes extremely limiting. Bend insensitive fibers can be used for sharp or tight bends, and this can be handled and laid far more easily. Bend insensitive fibers improve system margins in high speed enterprise networks.

What really happens is that bend insensitive multi-mode fibers minimize the bend-induced attenuation, thereby increasing the system reliability and decreasing the downtime. Less attenuation means that information transfer is more reliable. These cables also ensure that there is no chance of dealing with unplanned attenuation brought about by tighter-than-expected cable bends. New bend insensitive multi-mode fibers are able to deliver superior bandwidth performance in an ultra-bendable package without requiring any adjustments to standard field installation, termination monitoring, or maintenance procedures.

The Next Step
Every structured cabling vendor is making innovative efforts to make the fiber medium more adoptable for the benefit of enterprises. As a next step in Tyco Electronics' FTTH system solution, they have developed the wiring of multi-dwelling units (MDUs) with a mini break out riser cable, which is used inside the building from the outside plant cable termination to the customer's interface. These features are very compact to fit into small conduits and building floor access points, and are extremely flexible small diameter cables in combination with miniaturized cable accessories. It helps reduce the need for on-site pre-audits, and the horizontal drop cables can be pulled through the existing ducts due to their reinforcement. A reduced amount of connectivity points (splices, connectors) shorten the installation time, and the time spent inside the customer's premise is minimized in this advanced solution. It is optimized for brownfield construction networks.

Major industry players like DIGILINK are overhauling its offerings, and in days to come enterprises would get bend insensitive fibers as default. Other innovation required is to make the fibers less vulnerable to micro-bends by devising superior coating techniques. Improved dispersion by designing the preforms and pulse spreading performance are just a few to name on the innovations front. DIGILINK is the privileged partner to use the latest, being a preferred customer of Corning USA, pioneer in fiber technologies today. And, field crimping type fiber connectors (SM and MM) have been introduced in fiber components, which don't require epoxy. It takes lesser time to crimp the fiber connectors, and ensures low insertion losses.

Market Adaptability
According to industry sources, the bend improved G.657.A fiber has high market adaptability in India. This is set to increase in the coming years as bandwith requirements would drive FTTx to be a standard feature in India. The fibers are meant for datacom or LAN/ WAN applications, and this is a solution meant for our market. Hence, it is bound to become successful in the Indian market.

Bend improved G.657.A fiber is compatible with G.652.D fiber. The BI fiber offers a better macro bending loss, providing designer or installer with much more flexibility. People using fiber or installers laying it will be able to appreciate the advantages of bend insensitive fiber. Without doubt, freedom from the restrictions imposed by bend radia are highly desirable, and there is already an established case for this. Like any other new technology, price does play a critical role.

The only disadvantage with the fiber is the cost factor, which also would budge down as the demand increases. As bend insensitive fiber becomes increasingly competitive with respect to the present day fiber solutions, we will see a natural shift to this type of fiber as the medium of choice. Technology conscious customers would be very keen to see this happen very soon. Though the high cost is a deterrent at present, bend insensitive fiber's primary advantage of being less sensitive to micro bends and the resultant protection from transmission losses will drive the market. This cable can be installed even by unskilled installers.

The Driver
In the recent past, broadband upsurge in developing countries particularly in 'BRIC'-Brazil, Russia, India, China-there is a huge demand for a higher bandwith, especially in access networks. So FTTx (fiber to the home/business) is the primary driver in the enterprises to adopt this solution increasingly. However, adaptability will be there even in the LAN backbone segment for sure. There are three obvious choices for the technologies-XDSL, Wi-Fi/WiMax and FTTX. As enterprises inch towards the need for 1Gbs signal to an individual subscriber, whether at home (FTTH), or at the office desk (FTTD), or at the curb in your apartment (FTTC), there is no alternate to a passive optic network, leading to an extensive use of the fiber medium in the neighborhood.

The applications will be strong across all enterprise verticals. Since the advent of glass fiber as a communication medium from the early seventies, it has been preached and practiced that fibers are vulnerable to mechanical stress especially the bending stress. The fiber cable designs, essentially revolved around the philosophies to protect fibers from these stress. So FTTx segment will be the primary driver for this solution.

Basically, greater network reliability and less downtime, future proofed systems, easier installation across difficult geometries such as 90 degree bends, reduced time and cost for network installation with lesser bend radius precautions to be considered, and reduced operating costs of bend improved fiber solution would encourage enterprises to adopt this solution.

Bend insensitive fiber cable has generated quite a buzz in the market. It is a great step forward in optical fiber construction as it makes multi-fiber assemblies less susceptible to macro bends that affect the attenuation and limit the bandwidth of optical fiber links.

However, for enterprises of any size, it is crucial for the health and performance of their network to understand that the reduced bend radius fiber does not, in any case, mean that the fundamentals of proper fiber management are to be ignored. In fact, as bend improved fiber is deployed for any network using data intensive applications, factors such as connector access and cable routing paths become even more crucial. Last but not the least, deploying bend insensitive fiber is just one aspect of a complete strategy for an efficient, future proof network management across any enterprise.

Kannan K
kannan@cybermedia.co.in

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