In the highly competitive race for multi-dwelling unit (MDU) subscribers, service providers face a variety of platform options. Fiber-to-the-node (FTTN), fiber-to-the-curb (FTTC), fiber-to-the-building (FTTB), and fiber-to-the-home (FTTH) all have their upsides and downsides. Providers choose which type of network to deploy based on the building’s size and physical characteristics, existing infrastructure, regulatory concerns, and anticipated revenues, among other considerations.

Some service providers have made the bold move of taking fiber all the way into individual living units, wherever feasible, in order to offer subscribers first-class services and a future-proofed network. However, there is a trade-off. Deploying FTTH to MDUs can be fraught with complexities, particularly in brownfield properties.

Among the challenges of deploying FTTH to MDUs:
• Each unit must have its own optical network terminal (ONT). Subscribers sometimes balk at the bulky hardware taking up space in their homes, which, by design, are more compact than single-family homes, magnifying aesthetic considerations.
• The architectural design of many MDUs produces apartment layouts with many sharp corners and turns, further compounding the risk of over-bending the fiber cable and compromising signal performance.
• Standard drop cable pathway solutions can appear bulky and awkward inside the living units where, once again, visual impact is magnified.

However, in the last couple of years, suppliers have responded, developing hardware solutions that ease the pain of deploying FTTH in MDUs. Specifically designed for running fiber to the living unit, these products are compact, more flexible, and more sensitive to aesthetics of small spaces. They allow providers to install fiber to the living units quickly, easily, and cost-effectively while keeping subscribers happy with first-class services and minimal inconvenience or visual impact.

The ONT Comes Out of the Closet
When North American service providers first began deploying FTTH in MDUs, ONTs designed for single-family homes were the most likely option. However, the ruggedized, outside plant option isn’t practical for MDUs. It’s cost prohibitive for an indoor application and too unsightly for use inside the living unit.

Providers adapted by placing newly designed indoor, wall-mount ONTs that could be placed inside closets. The closeted ONT turned out to be a workable but less-than optimal solution.

Among the disadvantages:
• Many apartments and condos have small closets, and ONTs take up precious storage space -- undesirable to many subscribers.
• The ONT requires a power source, usually unavailable in a closet, requiring the installation of new electrical wiring and outlets.
• Running coaxial or CAT5 cable to the closet ONT to feed providers’ services to subscribers’ TVs, phones, and computers can require lengthy cable feeds -- adding time to installation and cost.

Service providers worked with suppliers, who quickly responded by developing the desktop ONT. First used in the U.S. in 2009, the desktop ONT is significantly smaller and lighter than its single-family counterpart.

Looking much like a wireless router, the desktop ONT could be placed in open living areas without objection, and is worthy of displaying next to the flat-screen TV where it can take advantage of existing power outlets and apartment wiring, reducing installation time and cost. Plus, desktop ONTs cost less, and use less power than their single-family counterparts.

Cost-effective and aesthetically pleasing, the desktop ONT marks a significant step forward in FTTH deployment to MDUs.

Bendable Fiber Adds Flexibility
An equally important innovation dovetailed with the advent of the desktop ONT: bend-insensitive fiber.

Conventional fiber optic cable can withstand a minimum bend radius of 30 mm -- roughly speaking, it can bend around a soda can at best. Any tighter of a bend and it begins to experience unacceptable levels of attenuation.

In MDUs, installing fiber cable within the acceptable bend radius often proves difficult, leading to 2 scenarios:

Scenario 1. The cable cannot be installed flush to the wall or baseboard around corners, producing unsightly gaps.

Scenario 2. The technician ignores the minimum bend requirement, leading to service complaints.

In 2002, the first bend-insensitive fiber cable was launched in the U.S. It was capable of a 10 mm bend radius without affecting signal performance. Since then, manufacturers have improved upon first-generation bendable fiber, developing fiber with an allowable bend radii of 7.5 mm and even as little as 5 mm, which can easily achieve a 90-degree bend.

Bend-insensitive fiber cable has found its true calling in MDUs. The ability of the fiber to hug the wall around the multiple sharp corners found in apartments and condos has significantly increased the aesthetic appeal of FTTH deployment while saving costs and minimizing service interruptions.

Out-of-Sight Pathways in the Unit
A third challenge involves running fiber strands from the hallway node into the living unit. To create pathways inside the apartment, ruggedized drop cables are often stapled along ceilings, door frames, and baseboards. In addition to being unsightly to many tenants, the long-term viability of this method is up for debate among cable manufacturers and industry experts. Some manufacturers say careful stapling using a rounded crown staple does not damage the fiber; others advise against stapling altogether. Moreover, in some situations, such as concrete walls and floors, stapling is simply mechanically impossible.

What to do? The stapling question can be avoided altogether by using an adhesive-backed cable pathway and bend-insensitive drop cable solution. One such product is the recently released 3M™ One Pass Mini Fiber Pathway that combines a 900-micron, ultra bend-insensitive fiber with a thin, low-profile cable pathway that adheres to the wall in just one pass.

This is a drop-cable solution specifically designed for the MDU living unit. It allows for quick, easy installation of fiber cable -- no staples required. It adheres to just about any painted or wallpapered surface. Flat and low profile, extending just 2 mm from the wall, it offers minimal visual impact compared to round, jacketed fiber cable, which can appear bulky. Plus, it can be painted to blend in with apartment décor.

It is also factory-terminated on one end, and can be cut to length on the other. That means minimal cable slack to wrap and hide in a storage box, thus avoiding yet another potential eyesore. The installer quickly and easily terminates the cut end with a field mount connector.

Together, the development of desktop ONTs, bend-insensitive fiber and products such as the One Pass Fiber Pathway have created a new fiber deployment solution, custom-made to address the unique challenges of FTTH deployment inside brownfield MDU living units.

As service providers continue to chase this competitive market, these three important advances can give providers the advantages of the aesthetics that subscribers demand along with quick, easy installation and cost savings.

An adhesive-backed cable pathway provides a low-profile, unobtrusive solution for deploying fiber within living units.

The mini pathway connects to a hallway distribution cable and is routed inside of a living unit to a wall outlet positioned near an ONT. Its adhesive technology ensures reliable installation on a wide variety of surfaces, even painted or sealed concrete where stapling cables isn’t an option.
 

Linnea Wilkes is business development manager, 3M Communication Markets Division. She has 5 years of experience in telecommunications, fiber optics, and premises network architecture, and more than 15 years of experience in bringing 3M products and solutions to bear for customers in numerous market segments around the world. For more information, visit www.3m.com/OnePass or email lmwilkes@mmm.com.

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