Network Infrastructure

Overcoming the Challenges of Fiber Deployment in Multi-Dwelling Units

By TMCnet Special Guest
By Linnea M. Wilkes
  |  December 10, 2012

This article originally appeared in the Dec. 2012 issue of INTERNET TELEPHONY.

The worldwide market for fiber-to-the-premises is estimated at more than 600 million living units. Given population density and economies of scale, the MDU category of housing has long been identified as an important growth opportunity for communication service providers.

Much attention has therefore been given to this market by service providers and their suppliers in recent years.

Yet a large portion of subscribers who reside in brownfield MDUs remain unconnected. Service providers face numerous challenges when designing and installing fiber networks within MDUs. Increased engineering, long installation times, and higher costs associated with fiber deployment have hindered the ability of service providers to fully realize the financial promise of the MDU category. No two MDUs are alike, and no single solution fits all.

These basic truths can immediately create physical and financial impediments for service providers.

Engineering challenges arise when attempting to retro-fit existing structures for fiber, and these can slow the installation process and add to its cost. But new – and decidedly smaller and more flexible – products are enabling service providers to meet pent up customer demand to deliver access to bandwidth-hungry multimedia services.

The evolution of key network components has led to game-changing solutions that make FTTP deployment in brownfield MDUs fast, easy, and low cost.

Drop Cable Evolution

In MDUs, installing standard fiber cable within the acceptable bend radius limitations often proves difficult. The architecture of such buildings requires cable placement to accommodate more, tighter bends than other housing categories. Standard single-mode fiber, due to its 30mm minimum bend radius limitation, cannot be installed flush to the wall or baseboard or tightly around corners, and that produces unsightly gaps that are usually not acceptable to aesthetics-conscious building owners and residents.

In 2002, the first bend-insensitive fiber cable was launched in the U.S. It was capable of a 10mm bend radius without affecting signal performance. Since then, manufacturers have improved upon first-generation bend insensitive fiber, developing fiber with an allowable bend radius of 7.5mm and even as little as 5mm, which can easily achieve a tight, 90-degree bend. The 5mm ultra bend-insensitive fiber drop cable is rugged and easily stapled to walls, facilitating quick apartment installations.

But there are problems. The stapling of cables is impractical in settings where plaster or concrete walls exist. And even though the cables can maintain an even tighter bend radius than their bend-sensitive brethren, UBIF cable drops are more bulky and difficult to conceal.

Cable Pathway Alternatives

Unlike new construction where cables are hidden behind walls at the time of construction, older buildings require cable pathway creation techniques that are aesthetically pleasing to owners and tenants. Durable, long-lasting installations and high-quality service is paramount.

From a service provider perspective, these cable pathways must also be cost effective.

Rigid crown moldings are offset about one to two inches from the ceiling, which allows jacketed drop cables to be tucked behind the molding and concealed from view. But this method is one of the most costly and disruptive to install.

Two-piece plastic square latch moldings consist of a base and a cover, which are somewhat lower cost. But this method requires significant custom fitting during installation because the molding is sold in standard lengths. Removal and replacement of the covers is required to place cables inside the molding, which adds to labor costs and deployment time.

Micro ducts placed behind walls and above ceilings is also a common two-step deployment method that almost completely conceals communication cables. The ducts first must be installed, and cables are later fished or routed through them. Often, this deployment method requires core drilling, a process of boring holes through one or multiple floors of a building that is expensive and time consuming. Core drilling through stacked closets in multiple apartments on multiple floors requires inconveniencing tenants, who must be at home so contractors can access the apartments during the installation process.

Stapling cables to the wall is one of the most frequently used horizontal cabling solutions. Particularly in apartments with more complex layouts consisting of a greater number of bends and turns, ultra bend-insensitive cables that are capable of maintaining a bend radius as small as 5mm (ITU G.657.B3) are often simply stapled to walls. From a visual perspective, most high-end building owners and tenants are unlikely to accept such a solution because it is noisy and can be dusty during installation. The end result gives a very industrial look.

The Fiber Pathway Option

A new solution has been developed to respond to several of the deficiencies of traditional FTTP deployment methods: the fiber pathway. This solution simplifies the process of drop cable routing through MDU hallways and interior spaces.

The fiber pathway is a contiguous, flexible, adhesive-backed, surface-mount indoor drop cable and cable pathway system that can be bonded to almost any wall surface, including concrete. Because the fibers are factory installed, the solution is installed simultaneously in just one pass around the perimeter of an MDU hallway or interior living unit. By eliminating the two-step process of building a cable pathway and pulling cable, service providers save up to 35 percent per floor when compared with traditional raceway or crown molding methods. The pathway is also paintable, blending easily into existing décor.

Two-person crews easily install the system using a handheld, pole-mounted tool that removes the liner from the adhesive backing on the duct and places the pathway and fibers, all in one quick and easy motion. Because adhesive is used to mount the pathway to the wall, installation is less disruptive than traditional methods. No stapling, hammering, sawing, or carpentry work is needed.

The pathway solution uses bend-insensitive 900μm fiber as the medium to distribute fiber optic services, making the pathway smaller than traditional optical cable pathway solutions designed to contain multiple 2, 3 and 5mm jacketed cables. This makes the system more discreet and less noticeable to tenants and homeowners.

The Big Push

The multi-fiber push-on connector was invented and introduced in the early 1990s to provide highly reliable connections in high density fiber applications, primarily in interoffice data network environments.

Today’s MT ferrules deliver much lower insertion loss capability with the advent of single-mode, premium performance ferrule technology, with typical attenuation values of <0.15 dB, and 0.35 dB Max/channel. Features vary by manufacturer, but many of today’s premium MT/MPO connectors offer improved mating durability via housing redesign, improved strain relief, and novel guide pin chamfer/radius designs that prevent guide hole damage in the opposing MPO connector. SM MPO connectors now are factory terminated with proprietary polishing processes that ensure precise fiber geometry and premium contact throughout the service temperature range.

With improvements made by suppliers to increase MPO performance, many service providers around the globe are re-discovering the MPO connector, and are finding huge benefits to its use as an enabler in a cost-effective connectorization strategy in the MDU category of residential housing.

Cables with factory-terminated MPO connectors provide top quality terminations and quick network installation at reduced labor costs. MPO connectors eliminate discrete fiber terminations so multiple customers can be turned on to services in a single step. They also allow for more connections in a smaller footprint, important in locations like stairwells and riser closets where space is at a premium.

When used with fiber pathways, an MPO terminated product can reduce equipment costs by eliminating the need for fiber distribution terminals on every floor. That speeds deployment time and reduces associated splicing, labor and material costs.

As service providers increased their emphasis on passing MDUs with fiber optic services, suppliers responded with the evolution of key network components. This evolution has, in turn, influenced a progression of advancements in FTTH and FTTH deployment methods, especially those specifically addressing fiber deployment in brownfield MDUs. The trend toward smaller, flexible components that are aesthetically pleasing to homeowners bring big benefits to service providers and a game changing strategy for future growth.

Linnea M. Wilkes is global MDU business development manager at 3M Communication Markets Division.

Edited by Braden Becker