Multi-dwelling units (MDUs) offer a key growth area for communication service providers offering high-speed, Triple Play products. But, for a number of reasons, fiber-to-the-home (FTTH) coverage for MDUs has started slowly.

Keep in mind that these structures represent over one-third of the target FTTH subscriber base and that a large portion of these subscribers remain unconnected to fiber optic networks. Given that, service providers are drawn to the economies of scale that make FTTH deployments to MDUs more cost-effective than to single family homes. Asia and Europe led the way in this market due to the high percentage of their populations living in MDU buildings. Now, American service providers have begun following their lead, installing fiber in more and more MDUs.

Deploying fiber to MDUs presents a number of unique installation challenges. In particular, the architecture of brownfield apartment and condominium buildings complicates installation. Many of these buildings were (obviously) built without present-day telecommunications technology in mind. They may lack hidden conduits or false ceilings through which to pull cable, making it difficult to lay fiber in a secure or aesthetically pleasing way. Pre-war plaster walls and ceilings are especially tricky to run cable along without damaging them. And where conduits do exist, they are often overcrowded, making it difficult to add new drop cables. In most cases, providers have to construct new cable pathways in hallways for fiber optic cables in order to deliver service to individual subscribers, adding to the cost of installation.

Solutions that allow for fiber drop cable routing within a hallway of an existing MDU can be expensive, time consuming to install, and can lack the aesthetic appeal desired by building owners and tenants to preserve the décor of their buildings. Service providers and their installation crews often use off-the-shelf crown or latch moldings to hide and protect fiber cable. However, these solutions have their drawbacks. A new innovation, however, is now allowing providers, such as Verizon, to deploy FTTH to MDUs quicker, easier, and at a lower cost while maintaining the aesthetic integrity of older buildings.

 Fiber Box

 Fiber Box

 MDU Cabling

Fiber Comes Out of the Closet
In MDUs with interior corridors, a wall-mounted fiber distribution terminal (FDT) is hung in a riser closet or stairwell on each floor. The terminal connects the building’s vertical riser, multi-fiber cables to horizontal drop cables run to each living unit. These drops are typically placed only when customers request service, requiring a significant amount of time and multiple truck rolls to connect service. More often than not, a new cable pathway must be constructed to route these cables. Existing pathways, if they do exist, are often congested and unable to accommodate new drops.

Many of the cable pathways on the market today require a considerable amount of carpentry to install. For this reason, service providers may contract vendors to place common solutions, such as off-the-shelf crown molding or extruded plastic, square latch moldings throughout the corridor, near the ceiling. A fiber optic pigtail is then tucked behind the crown molding or, in the case of the square latch moldings, placed inside. One end is often factory terminated and is plugged into the optical network terminal (ONT) in the customer’s living unit while the other end is often fusion spliced in the FDT.

These solutions certainly work, but they leave opportunity for improvement. Cost of these solutions is of particular concern for network operators. Deploying fiber to MDUs has commonly turned out to be a time-consuming, costly, two-step process, usually requiring two separate crews -- one to build the cable pathway and one to lay the cable.

Pathway construction requires cutting moldings to length in hallways and the use of nails, anchors, and screws to fasten them to the wall. It can be a loud and messy process, potentially disturbing tenants. And, because the moldings are rigid, they are difficult to conform to the wall surface of older buildings, which may have curved due to settling over time. The end result, if not constructed by skilled craftsman, can be unsightly and/or not fit in with the building’s décor.

A Hall Pass?
A new solution simplifies the process of drop cable routing through MDU hallways. The recently released One Pass Fiber Pathway from 3M is a flexible, surface-mount, adhesive-backed indoor drop cable and cable pathway system installed simultaneously in just one pass around the perimeter of a MDU hallway. It is designed specifically for deploying FTTH to MDUs and comes in reels of 100, 200, and 300 feet, allowing for fast, seamless installation. It is also paintable, allowing it to blend into just about any décor.

The low-profile duct combines the pathway and the fiber drop cable in one solution, eliminating the two-step process of building a cable pathway and pulling cable. Two-person crews easily install the system using a handheld, pole-mounted tool. The tool removes the liner from the adhesive backing on the duct and places the pathway and internal fibers, all in one motion. The adhesive does away with the need for messy, labor-intensive construction and sticks to a wide variety of finished wall surfaces.

Six or 12 bend-insensitive single-mode fibers reside in the duct. These 900µm tight buffer construction fibers allow for tight diameter coiling and storage within small point-of-entry boxes as well as low-loss routing around multiple 90-degree corners. Therefore, the duct can be installed in the most challenging MDU corridors to provide the service integrity customers expect.

This new solution enables service providers to pre-position a fiber outside each living unit. The fiber is terminated with a no-polish field terminated connector and stored in a One Pass Point-of-Entry Box. This provides a test access point outside the customer's premises. It also shortens the amount of time required to connect the final drop. When a tenant subscribes to service, a technician simply opens the point-of-entry box, drills a hole into the living unit, and, using a factory-terminated jumper, connects one end to the adapter in the box and the other to the ONT in the living unit.

Verizon, a pioneer in FTTH deployment, was one of the first to use this system in a test trial in New York City earlier in 2009. The trial proved to be successful, allowing Verizon to reduce labor and material costs. Verizon's FiOS services delivers the fastest Internet connection, the most HD channels (on FiOS TV) and phone service on an all-fiber-optic network to MDUs, multi-tenant units (MTUs) and single-family units (SFUs).

In addition to MDUs, this strategic solution can also aid fiber deployment in schools, hospitals, hotels and small businesses.

As service providers continue to expand their fiber networks into MDUs and other multi-tenant buildings, solutions tailored to the application and the environment, new innovative solutions such as the 3M One Pass Fiber Pathway will help those providers deploy their services quickly, easily and cost-effectively so that everyone can enjoy the latest technology in their homes, classrooms, and offices.

About the Author
Linnea Wilkes is business development manager, 3M Communication Markets Division. She has 4 years of experience in telecommunications, fiber optics, and premises network architecture, and more than 14 years of experience bringing 3M technologies and product solutions to various markets. For more information, visit www.3mfiber.com or email lmwilkes@mmm.com.