Engineering “Every Last Mile”

As America targets efforts towards connecting every community to robust broadband - including the distribution of more than $40 billion in federal funds for building new networks - cable providers continue to do what they have always done: build out their networks to reach as many Americans as possible.

Expanding networks to remote communities often involves difficult terrain with extreme climates, creating a lot of logistical challenges for crews and engineers. Earlier this year, NCTA premiered "Every Last Mile" a docufilm detailing the hard work crews face delivering broadband service in harsh conditions and distant locations.

Crews aren't alone in having to adjust their work to extreme conditions. NCTA asked Curtis Knittle, Vice President of Wired Technologies at CableLabs what considerations must be accounted for on the engineering side to deliver broadband in tough conditions and rural areas.

NCTA: How do different terrains and conditions impact how a physical network comes together? If a project is expected to go through areas with extreme winters, scorching summers, or rocky terrain, how do those kinds of things impact how the network gets built?

Knittle: One of the most important factors that determines the complexity relates to whether the [infrastructure] is aerial or underground.

For aerial deployment, extreme environmental conditions at both ends of the spectrum pose challenges.

• In extreme winter conditions, the cold weather and windy conditions will be the largest contributor to slow progress. These conditions will mostly impact the workers who are installing fiber cabling.
• At the other end of the environmental spectrum, extremely hot conditions also have the potential to create hazardous working conditions.

For underground deployments, the situation varies widely.

• Extreme winter conditions have the potential to cause the ground to freeze, increasing the difficulty of underground drilling.
• The depth of the cable may be such that it is below the depth of freezing, thereby mitigating this particular concern.
• The bigger concerns are the characteristics of the ground and terrain:
  • Drilling through rocky ground increases costs and schedule.
  • Terrain containing cliffs will also present a challenge, increasing costs and schedule.

What has to be done to protect network equipment from these extreme conditions?

Typically, devices deployed in extreme conditions must be designed and manufactured to support industrial temperature ranges, defined to be -40°C to +85°C (-40° to 185°F). Additionally, the device housing must be waterproof.

Often, outdoor network devices are placed in nodes or cabinets, so these enclosures must be waterproof and allow for appropriate heat dissipation.

What are the technical challenges that come along with extending networks in rural, sparsely populated areas?

Facility existence: More than likely, new facilities (e.g., headend, hub, central office) will need to be built to support network equipment like Cable Modem Termination Systems (CMTSs) and Optical Line Terminals (OLTs), as well as long haul optical links to backhaul data to/from the main service provider facilities.

Electrical power to outside plant devices: While it is obvious that the facilities (e.g., headends/hubs/central offices) will require power, many of the devices for residential data service are located in the outside plant, far away from the facilities.

Long distances: Many of the residential service technologies come with distance limitations.

• For hub-based OLTs in fiber to the premises deployments, the technology is limited to between 20km and 30km, depending on how many homes are connected to the optical distribution network.

Cost per home: One can imagine having to build facilities, install outside plant, network devices, etc., for a small number of homes. The cost per home becomes exorbitant.

To learn more about the work being done to connect every American, be sure to visit NCTA's website and watch "Every Last Mile."

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