Using Microduct in the Cellular World

By TMCnet Special Guest
Cheri Beranek, President and CEO of Clearfield Inc.
  |  December 26, 2013

With the onset of LTE (News - Alert) and other broadband hungry technologies, cell tower owners and operators have seen the need to not just bring fiber to the base of the tower, but to take fiber up the tower as well. Unfortunately, the boost in performance achievable with fiber is seen as a trade-off with the cost of installing it.

Nonetheless, radio and antenna manufacturers have begun to equip their products with fiber-ready connections. The struggle today is what to do with the large coaxial cables that both weigh down the tower structure and add to wind loading. There are a number of towers that were not designed to take the extra loading that the LTE technology adds.

The answer to this is microduct.

Microduct not only reduces the cost of installation, but it lowers the weight placed on the tower as well. It has such a small footprint, yet can provide nearly 100 times the capacity of broadband over that of a typical coaxial cable. By taking the microduct up the tower (using the traditional hardware), then breaking out the fiber into a distribution box on the tower deck and running the same style of microduct to each radio location, the tower crew can remove all the coaxial cables and replace it with one 10mm microduct.

On a multi-carrier tower, this can remove in excess of 40,000 pounds from the tower and provide monumentally greater capacity. Since top quality microduct can house 24 fibers, there is no need to run multiple ducts up the structure. Incidentally, the same microduct can be used to provide service to the tower from the local carrier.

The cost associated with a typical tower installation crew of four people (twoclimbers and two ground people) comes to an average cost of $75 an hour per person. A typical installation would involve taking six coax cables to the tower deck using a capstan or a crane. Crane costs are upwards of $3,000 per day. It would take an experienced crew 15 hours to run the cables up the tower and place them at their designated spot on the tower. This does not account for routing into a hut or other structures on the ground. If a crane is used, that cost alone is typically $6,000.

In contrast, a typical microduct installation would consist of taking one microduct up the tower to a breakout box, then running microducts to each radio head. The structure is now ready for fiber. If the operator orders a fiber with a pre-connectorized Clearview Cassette, the tower crew only needs to pass the tail down the microduct to the splice point at the base. After the tail reaches the bottom, the crew simply snaps the cassette into the breakout box. Each radio with a microduct can be turned up by simply pushing a FieldShield pre-connectorized jumper through the duct and plugging it in on each end. The work on the tower deck is now complete. Because of the small size of the FieldShield fiber, the climbers can take the fiber up the tower with them. Again, there’s no need for expensive cranes on site.

The average time for this style of installation is between two and Three hours. Multiplying the time required by the labor rate of $300 hour, the labor costs will equal $900. With no crane costs, the total cost of a microduct installation of 24 fibers is under $1,000.

For comparison let’s assume we have the same four people on a crew for a traditional installation. A traditional installation is estimated to require 15 hours at a rate of $300 an hour. Multiplying time by rate and adding the $6,000 crane costs, and the total will easily exceed $10,000 for a typical installation of six coax cables.

With the price point of fiber falling below copper and the lower weight of the medium reducing wind sheer, it would seem that microduct is the easy choice. But, be cautious – traditional microduct designs have and will fail over time in this type of deployment. With the advancement of polymers and coatings, today’s microducts and fibers (when used as a system) can and will withstand the rigors of direct placement in environmentally harsh environments. Further, attention must be given to the distribution of the fiber at both the top and foot of the tower to ensure appropriate protection and management of the fiber over time.

Cheri Beranek is president and CEO of Clearfield (News - Alert) Inc. (www.clearfieldconnection.com).

Edited by Cassandra Tucker