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Delivering fiber successfully to MDUs and office blocks

Posted by Dave Daly

MDUsThe advantages of fiber optic cable over copper wire are well understood. Fiber can transfer more data, in less time, over longer distances than copper. It does not degrade like copper, requires little maintenance and loses only a fraction of its signal strength over 100 meters.

Today, there is a growing demand for fiber, as consumers expect faster Internet speeds. This demand is largely being fuelled by video and music streaming services and over the top (OTT) bundles. Additionally, businesses also require faster broadband, to grow and scale their organisations in a digital and global world.

In this post, we will explore how fiber is successfully delivered to multi-dwelling units (MDUs) and commercial buildings.  

Delivering fiber to MDUs and office blocks  

There are typically three phases to installing fiber in an MDU or commercial building. First, the fiber has to be taken from the curb into the building. Then, it needs to be routed from the basement to each floor in the building. In the final phase, the cable has to be brought into individual apartments. Different techniques can be applied at any stage in the process. 

1. Fiber from the curb to the building  

The fiber is routed from the curb to an outside distribution box. In most cases, it is then brought inside the building. However, in some parts of the world – like the Middle East – it is common practice for operators to install single fiber cables from the outside distribution box directly to the individual apartments in point to point (P2P) cable run through ducts and on the exterior walls of the building.

To get fiber into a premise, a cable has to be routed from the point of presence into the building through the wall, and plugged into a further distribution box or distribution frame in the basement or a comms room. Having the fiber distribution point inside the building extends the network lifecycle by increasing its protection and speeds up the whole process of installation.

Once the fibers have been brought onto the distribution frame (or, for small scale MDUs, the distribution box), they will then need to be connectorized. The most popular connectors used are SC and LC with angled end faces.

There are three main options available for operators to connect the distribution box or frame to the floor level boxes. They can use pre-terminated indoor drop cables, use mechanical or fusion splice connectors, or they can fusion splice onto pigtails.

2. Fiber to the floor

Next, the fiber cable needs to be routed from the basement of the building to each floor. In new build apartment blocks and commercial buildings, this step is relatively straightforward, as, usually, the architect will have designed the building with fiber in mind and installed a microduct from the basement to each of the floors. The network operator then has the option of blowing, pushing or pulling the fiber cable from the basement to each floor.

In older buildings, there may only be PVC electrical conduits in place. In most instances, they are pre-populated with other types of existing infrastructure. While a well-routed microduct path might allow 50-100 meters of cable to be pushed and/or pulled through it, a congested and ill-planned conduit might only accept 15-25 meters of cable inside. And sometimes there will be no obvious means of getting the fiber to the floor at all. In this situation, or when there is no pre-existing infrastructure in place to transport the cable, operators should use whatever spaces are available in the building.

Whatever type of cable is used for this stage of an in-building installation it needs to meet local fire regulations.

Whether the cable is routed through an existing conduit or not, it will invariably terminate at a box on the floor. Again, network operators then have the choice of splicing fibers at the box or using a pre-terminated wall box.

3. Fiber to apartment or office

delivering_fiberThere are several viable options that work for the last leg of an in-building fiber installation project – namely direct fixing, pulling and pushing. In select cases, blowing may be an option if there is a duct leading from the floor into each apartment. 

For pulling, the ideal scenario is to source microducts with pulling rope or cord preinstalled. The cable is simply tied to the pull-cord or secured inside a pulling sock, before being pulled through the microduct. Pulling is often preferred by installers because it’s quick and reliable, with comparable distances to blown fiber and none of the mess.

Failing a pull-cord being present, a conduit must first be rodded before the cable can be pulled. This can be a lengthy process because the rod has to push past obstacles in the conduit before it can be attached to the cable, effectively enacting twice the installation time and effort in a push and pull process.

With pushing, the selected cable should be flexible enough to push around corners, yet stiff enough not to buckle in long routes where high levels of friction are generated. In many respects, pushing is much simpler – there is only one step in the process. In addition, pushing the cable into a microduct or conduit applies zero tensile load to the cable, reducing the instances of damaged cable or strained fiber.

When rodding/ pulling seems like the only option, pushing can be a viable alternative solution, provided the cable has the right characteristics. It may take one to two hours for an operator to rod a conduit and pull cable from the floor into an apartment. The same operation will take a fraction of the time with pushing.

The final step of the process involves connecting the fiber to the media converting equipment in the apartment. Typically, the fiber has been pushed, pulled or fixed as far as a wall box terminal in the apartment or office entrance.

If the fiber has been pre-terminated it will then simply connect to the service provider’s equipment (media gateway), either directly or via a short fiber patch lead. If the fiber is bare, however, it will first require the splice technician to furnish the fiber with what is typically an SC or LC format connector.

From there, the data is translated by the gateway into a range of different signals for both copper and wireless communications used in and around the home or office. If the preferred location for the gateway is not where the fiber has currently been installed to, a longer patch cord can be used to move the point of presence, often referred to as the optical network terminal (ONT). 

In-building fiber installations don’t need to be painful experiences. If managed properly, they can be carried out quickly and cost-effectively with minimum disruption to the customer. Most importantly, they can deliver what an operator values most – a genuine return on investment.

In-building

Topics: Design and Install, MDU

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