Cable Television Laboratories Inc. has announced the latest addition to the
Data Over Cable Service Interface Specification line aimed at boosting upstream
bandwidth for cable-modem systems.
The newly born DOCSIS 2.0 specification uses advanced physical-layer
technology (PHY) to quadruple upstream throughput, potentially opening more
doors to symmetric high-speed service targeting coveted business customers.
The cable-industry consortium announced late last week that it will have the
2.0 specification ready by the end of the year, with interoperability tests and
certification waves targeted for 2002.
The specification promises to boost capacity for data traveling from the
cable-modem user to the central cable network from 5 megabits per second for
current DOCSIS 1.0 modems on a 6-megahertz channel to 30 mbps. It also promises
to clear up signal-interference problems on the upstream channel.
While cable operators have not faced significant congestion with upstream
capacity among residential users, widening the capacity will open more doors for
enterprise customers interested in symmetrical speeds for business
'We're trying to get to symmetrical services here,' said Rouzbeh Yassini, an
executive consultant who is overseeing the cable-modem initiative at CableLabs.
While cable operators have several options to accomplish this, including
installing fiber line to the user, 'this technology will give them the best
fixed-cost price on the upstream channel,' he added.
DOCSIS 2.0 will use synchronous code-division multiple-access modulation
(S-CDMA) -- which has been strongly backed by cable-equipment maker Terayon
Communication Systems Inc. -- and advanced frequency-agile time-division
multiple access (A-TDMA). Using both schemes will give cable operators greater
flexibility in adapting advanced PHY capabilities to their existing systems,
The technology will also be compatible with DOCSIS 1.0 and DOCSIS 1.1, so
cable operators won't face having to swap out entire cable-modem systems,
Cable operators will be able to install 2.0 line cards to existing
cable-modem-termination system units or buy units configured for DOCSIS 2.0.
Either way, the controllers would still support modems on the older DOCSIS 1.0
and 1.1 schemes, but users would have to have 2.0-compatible modems to take
advantage of the boosted upstream bandwidth.
'This is going to be transparent, basically,' Yassini said. 'Because of the
coexisting, because of the backward compatibility, the system will work
For Terayon, the announcement is a major validation of a technology it has
supported since 1994. The vendor currently has some 1.8 million S-CDMA modems
deployed around the world, but the numbers could swell with a standard to rally
around, according to Rich Prodan, senior vice president and chief scientist.
'The whole idea now that we have a standard-based technology for Terayon's
innovation in transmission technology opens up a wide market -- a huge market,'
Prodan said. 'If Terayon would only get 20 percent market share worldwide, it's
huge compared with 100 percent of the proprietary market we now enjoy.'
Terayon isn't the only vendor cheering the DOCSIS 2.0 initiative. Pacific
Broadband Communications has announced that it will release a CMTS in the fourth
quarter that will be compatible with the new specification.
Meanwhile, CableLabs is also nearing the end of a certification round for
DOCSIS 1.1 modems later this month. Thus far, no modems have been certified for
1.1, which adds quality of service needed to support cable-telephony
applications. Yassini said DOCSIS 2.0 will be a good follow-up.
'Having a new technology as a specification is a complement to the existing
infrastructure,' Yassini said. 'So I see them almost adding together as a very
nice domino effect -- 1.0 being commercial deployment, 1.1 being certified, and
now we have advanced PHY at the specification phase.'
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