Bridging the Fiber Gap

Jun 30, 2014 by Prayson Pate

Overture CTO, Prayson Pate

Fiber is the clear choice for delivering innovative high-speed services at the edge of the network, and the amount of deployed fiber continues to grow.  However, the availability of business access to fiber remains relatively low and even lower for residential areas.  In both cases, the cost of new fiber construction is high.  How do we close the gap between the need for high speed access and the limitations of deploying fiber?

I recently had the chance to discuss this dilemma when I joined a panel for a meeting of the Telecom Council of Silicon Valley.  The meeting was a “deep dive” focused on last mile access, and my panel was on the topic of “To fix or not to fix?” the last mile. That is, do we keep and use existing copper, or do we replace it with other access?  I believe that the answer is “all of the above, where appropriate.”

Here at Overture we support delivery of advanced business services over all media, including not only direct fiber but also TDM, SONET and EFM copper.  As such, it may sound strange to hear me say that we also support the goals of all service providers, which are to get user services onto fiber and to push fiber as close to the customer as possible.  In fact these positions are quite consistent.

According to Vertical Systems Group, only about 40% of U.S. business buildings are reached by fiber[1].  The cost of fiber construction is prohibitive for some other locations, and another set are simply off-limits due to ordinances against digging holes or stringing aerial fiber.  That means that, in many cases, the access to the subscriber must be over some other media.  The two top choices are 1) existing copper and 2) wireless technologies.

VDSL2 and vectoring have helped increase the bandwidth available over existing copper pairs, and G.FAST promises to drive the speeds even higher.  However, these increases in speed come with a corresponding reduction in the maximum allowable distances.  In the case of G.FAST, the distance is likely to be limited to less than 100 meters, which means that small DSLAMs will have to be deployed very close to the subscribers, and that fiber will have to be extended out to these small DSLAMs.  In other words, using existing copper will drive the need for more fiber penetration.

An alternative is to use wireless technologies such as LTE and WiFi.  There is a fixed amount of bandwidth available in a chunk of spectrum, so LTE increases the speed available to users by making the cells smaller and more numerous.  Likewise, any use of WiFi will have to be limited to very short reaches.  As with the use of existing copper, the use of wireless technologies just drives the need for more fiber.

Given this need for more fiber pushed deeper into the network, one might ask whether it is even worth bothering to leverage copper and install wireless technologies for reaching the subscribers.  The answer is a resounding “yes.”  While these access technologies do drive the need for more fiber, they eliminate the biggest components of the overall cost: the need to touch every residence or business building with fiber.  By using these alternative access technologies for the final segment, the expense of deploying fiber can be spread across multiple users, without having to incur the large cost of reaching them directly with fiber.

The bottom line is that we do need more fiber, but we also need to leverage existing copper and deploy wireless to feed it.  Any service provider that ignores this powerful combination is going to put itself at a disadvantage.

About the Author

Prayson Pate is Chief Technology Officer and SVP of R&D at Overture, where he is also a co-founder. Prayson is a technology leader and evangelist with a proven track record leading teams and delivering products. Since 1983 he has been building Carrier Ethernet and telecom products for service providers and network operators around the world - both as an individual developer and as a leader of development teams. Prayson spends much of his time driving adoption of Overture's new Ensemble Open Service Architecture, which includes aspects of automation, virtualization, SDN and NFV. He has a BSEE from Duke, an MSECE from NC State and is the holder of nine US patents.

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