Cable’s next major broadband
technology platform may throw DOCSIS
out the window — but it is envisioned to
let operators economically deliver gobs of
bandwidth over existing coaxial cable.
CableLabs, the industry’s research-and-development
consortium, is in the earliest stages of
investigating a new platform for data-over-coax
transmission reconceived from the ground up,
according to people familiar with the project.
The concept: to be able to blast up to 5 Gigabits
per second, or even more, downstream.
The new platform potentially represents a
major architectural change for existing cable
systems. “It’s almost a complete relook
at how you do data over coax,” said a cabletechnology
executive briefed on the Cable-
Labs project. “If you were to convert all the
spectrum in a typical cable system to data
you could easily get 5 Gigabits per second.”
But there are a number of caveats.
CableLabs currently is only investigating
the approach, and the work might not ever
result in a technical specifi cation.
Also, this new data-oriented technology
most likely would not be compatible with
current DOCSIS cable modem equipment.
Asked to comment on the project, CableLabs
spokesman Mike Schwartz said, “CableLabs is
in business to explore many different technologies
on behalf of its members.” He declined to
The initiative underscores the industry’s position
that the hybrid fiber-coax (HFC) network
architecture will be sustainable for many years
— if not decades — without requiring a complete
Executives familiar with the project said CableLabs
is exploring new advanced media access
control (MAC) and physical-layer (PHY)
components for cable broadband equipment
that would do away with the traditional 6-MHz
channel divisions used in cable systems today.
Theoretically, CableLabs’ current DOCSIS
3.0 spec can deliver multiple gigabits-persecond
speeds. The specification “bonds”
multiple 6-MHz channels together to aggregate
the bandwidth provided by each one
(typically about 38 Mbps downstream).
The post-DOCSIS approach, by eliminating
the 6-MHz divisions, potentially would
be far more efficient.
Even if the new data-over-coax platform
never sees the light of day, DOCSIS 3.0 should
provide cable operators ample bandwidth
delivery for the next several years. The specification requires support for a minimum of
four downstream channels (for a total of 160
Mbps) but chip suppliers have already delivered
eight-channel products that deliver
more than 300 Mbps downstream.
LIFE AFTER DOCSIS
data-over-coax project could:
■ Be capable of efficiently
delivering 5 Gbps or more.
■Eliminate 6-MHz channel divisions.
■ Introduce new MAC and PHY
■ Likely not be backward-compatible
with current DOCSIS equipment.
SOURCE:Multichannel News research