Move over fiber: Cable TV modems may soon leave you in the
dust.
That's right-optical fiber-to-the-home service had previously
offered the fastest available connection for residential Internet.
The best-known example is the FiOS service from Verizon
Communications, which peaks at 50 megabits per second.
But the cable industry has recently taken the wraps off new cable
modem technology that exceeds the FiOS speed by a factor of more
than three. Called the Data Over Cable Service Interface
Specification (DOCSIS) 3.0, it allows data throughput of as much as
160 megabits.
"The technology lets you bind together cable channels and then run
data over those combined channels-you don't need more wires," said
Mike Schwartz, spokesman for Cable Television Laboratories
(Cablelabs), which defines operational specifications for hardware
used in the cable TV industry, assuring interoperability.
Each digital channel can provide a bandwidth of 40 megabits, so
binding them together provides multiples of that throughput, he
said-although the user will have to sacrifice several program
channels. With four channels consumed by Internet bandwidth, the
user will get 160 megabits downstream (from the Internet) and 120
megabits upstream (to the Internet).
"Cable systems are looking at their ability to deliver high data
speeds, and are putting channels aside to assure that kind of
throughput when the market requires it," Schwartz told
LiveScience.
The DOCSIS 3.0 modems will work only on digital networks, and only
after appropriate "head-end" transmission systems have also been
added.
Schwartz estimated that DOCSIS 3.0 modems would start appearing on
the market early next year, although the carriers would also need
DOCSIS 3.0 transmission gear, and none has yet been submitted to
Cablelabs yet for interoperability testing. But Schwartz said there
is plenty of time for that.
As implied by the name, these modems represent the third generation
of the DOCSIS standard for digital cable TV networks. Version 1.0
offered 10 megabits, and version 2.0 offered a maximum of 40
megabits, Schwartz said.
The first operational DOCSIS 3.0 modems were shown recently at an
industrial convention in Las Vega by Comcast Corp., and one was
reportedly was used to transmit a copy of the 2007 Encyclopedia
Britannica, plus a Merriam-Webster's dictionary, in less than four
minutes.
The cost of the modems, it was announced, would be similar to that
of current modems.
But fiber will probably not lie down and die, since the technology
offers the potential for enormously higher speeds in the future.
The speed of a fiber connection is determined by the speed of the
electronics at either end, since the capacity of the fiber itself
has been found by researchers at Bell Labs to be an astronomical
100 terabits. That's 100 trillion bits per second, or 666,667 times
faster than a DOCSIS 3.0 modem.
Schwartz estimated that the maximum capacity of a cable modem line
is ultimately about 5 gigabits.