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BROADBAND COMMUNITIES
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www.broadbandcommunities.com
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JANUARY/FEBRUARY 2015
TECHNOLOGY
Comparing Cable
And Fiber Networks
Fiber networks are capable of sustained, symmetrical 100 Mbps service that cable
networks cannot match.
By Andrew Aferbach, Matthew DeHaven, Marc Schulhof and Eric Wirth / CTC Technology & Energy
C
able broadband technology is currently
the primary means of providing
broadband data service to homes and
businesses in most of the United States. Hybrid
fber-coaxial (HFC) cable networks will be the
main pathway for broadband communications
for most homes and businesses for the
foreseeable future because of their ubiquity in
populated areas and their inherently greater
capacity than commercial wireless solutions and
copper telephone lines (the medium underlying
DSL service).
However, cable networks face signifcant and
costly challenges to achieve the performance,
capability and scalability aforded by fber-to-
the-premises (FTTP) networks.
Tough cable operators widely ofer
download speeds of "up to 150 Mbps" over
their HFC networks, they are unable to support
these speeds on a sustained basis for a large
percentage of customers simultaneously without
signifcant upgrades to their networks. On the
other hand, most current FTTP deployments
can provide sustained speeds ranging from
100 Mbps to 1,000 Mbps at one time, to all
customers, with the ability to scale network
capacity exponentially with relatively minor
upgrades. Depending on the technology used,
FTTP can provide sustained symmetrical
services at these speeds; most cable operators
limit their residential service oferings to 20
Mbps or less in the upstream direction.
HOW DO CABLE SYSTEMS
DELIVER DATA?
Te delivery of Internet data services over
traditional HFC cable television systems was
standardized by a nonproft research and
development consortium, Cable Television
Laboratories (CableLabs), and ratifed by the
International Telecommunication Union (ITU)
under the name Data Over Cable Service
Interface Specifcation (DOCSIS).
DOCSIS is the technical standard by which
data communications can occur bidirectionally
over a cable TV system. Like cable television
services, DOCSIS uses separate channels
within the radio frequency (RF) spectrum of
the network cable plant. Traditionally, cable
television channels each use 6 MHz of spectrum.
Te latest deployed version of the
standard, DOCSIS 3.0, enables combining,
Learn more about the
advantages of FTTH technology
at the
BroadBand Communities
s
ummit in Austin, April 14–16.