By Venk Mutalik, Pat Wike, Doug Combs, Alan Gardiner, Dan Rice; Comcast
London Underground or the ‘Tube’ began as a modest steam rail system over 150 years back and is now a sprawling transit system transporting over 5 million people daily. Similarly, Comcast began modestly but today has a large and growing optical footprint with fiber getting deeper into the network often leading to challenging underground fiber construction in the neighborhoods. Just as generations of Tube engineers innovated on their predecessors’ plans deep underground and grew their rail network, Comcasters innovate on critical infrastructure built by our cable predecessors and provide higher capacity to match current demands and future needs.
In this paper, we report on the use of innovative technology that enables us to use existing underground critical infrastructure and make fiber deployments in the neighborhoods simple, cost effective and minimally customer impacting. Cable companies have been laying underground RF cables inside conduits, in vast sections of cable builds since the mid 1990s. This process, called Cable in Conduit (CiC) has a fraction of the conduit occupied by the RF cable with a contiguous empty space in the conduit. Recently, fiber manufacturers have come out with ‘micro-fiber’ cable that bundles of up to 72 optical fibers occupying a diameter of only a few millimeters. This new fiber cable bundle is supple, affords tight bend radius and has good tensile strength. With existing rod-rope-pull equipment this micro-fiber can now be deployed within the existing conduit alongside the RF Cable cost-effectively, quickly and with minimal impact on the customer experience, all without the need for trenching or boring.
The paper describes details of trial activities on CiC in one of our divisions and the economics of this technology. Skillful use of this technology and innovative optical systems being developed bring fiber to the last active, simplify other architectures such as Full Duplex (FDX), improve performance and capacity overall and help propel new optical architectures such as Switch on a Pole/Pedestal (SOAP). Since this technology provides large fiber counts at RF tap locations very close to our customers, it provides great long-term opportunities to span the last few meters and reach customer homes (FTTH) when needed.