Connectivity in focus for multi-dwelling units

Recent documents emphasize the important role of fiber-optic connectors in service-provider MDU installations, touting one approach in particular.

By Patrick McLaughlin

Two documents recently published by CommScope drive the point home for service providers that their choice of connectivity can significantly impact their ability to efficiently turn up services at multi-dwelling units (MDUs). The documents, titled “The flexible architecture series: Connectorization in the MDU,” and “New techniques for reducing time and cost of MDU installation,” were published in late 2015 and emphasize the benefits of preconnected systems over splicing in the field.

“MDUs represent an enormous opportunity for service providers,” one paper states. “However, with their conduits and wide variety of layouts, they also present some unique challenges, requiring service providers to spend a great deal of time in planning and installing the fiber infrastructure.”

The document compares different approaches to connecting the same hypothetical MDU-a high-rise building with 23 floors and 15 units per floor. In a stub-pull configuration, “Fiber distribution terminals (FDTs) reside on each floor of the building that route 12 or 24 fibers down to the indoor fiber distribution hub (FDH) where they are typically spliced in. In this example, 432 fibers would be spliced between the FDH and the FDTs. Three hundred forty-five individual drop cables would then be run from the FDTs to the optical network terminals (ONTs), creating another splice point.”

In a loop-through configuration, “A 432-fiber indoor FDH is located on the lower level,” the document explains. “Several 72-fiber or larger distribution cables are pulled between the FDH and FDTs on higher floors. On each floor, one of the cables is routed through the FDT, opened, two of the 12-fiber ribbons are opened and 15 individual fibers routed to the splice tray in the FDT. In this example, 345 fibers would be spliced between the FDH and the FDTs.” As in the stub-pull configuration, 345 individual drop cables would run from the FDTs to the ONTs, creating a splice point because “it is not possible to predict the exact length of each drop,” CommScope notes.

The document then describes what it calls the “rapid fiber configuration,” and makes the case for it being the most-economical, most-efficient approach. “In this case, an FDT again resides on each floor, but an MT connector is mounted on the stub of each. The fiber is deployed from each FDT to the indoor FDH, also with built-in 12-fiber MT connectors. Each connection is easily plugged into the FDH from every floor. Installing fiber into an MDU is a simple matter of mounting the enclosures and making rapid fiber connections with the cables.”

This “rapid fiber configuration” is based on the company’s Rapid Fiber product line, which includes spooled preterminated fiber. When describing the system’s use in this hypothetical MDU, the document explains, “Since distances vary from each FDT to the FDH, a built-in fiber spool is designed on the FDT. The spool holds up to 500 feet of fiber cable. Therefore, the cable is easily spooled out to the FDH and plugged in, while any extra cable remains on the spool.

In conclusion, CommScope acknowledges, “The MDU market segment, with its broad range of architectures and the time and cost pressures of installing next-generation fiber networks, presents service providers with some difficult challenges.” It maintains that when service providers adopt a specific strategy related to connectivity versus splicing, they can reduce planning and installation time, minimize the number of splices and technicians required, deploy a smaller installation team, and reduce overall installation costs.

Patrick McLaughlin is our chief editor.

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