DOCSIS Isn't Done With Supporting Data Business


Boulder, Colo.— The Data Over Cable Service Interface Specification has grown from a data novelty to a worldwide technology, but even in the midlife of its development, the upgrade work isn't complete, according to Cable Television Laboratories Inc.

The technology consortium, which developed the landmark family of specifications for broadband cable-modem systems, gave an update on DOCSIS adoption trends and improvements at a media briefing last week.

Throughout the world, 23 million DOCSIS 1.0 products were shipped in 2002, including some 228 certified cable-modem products and 29 qualified cable-modem termination units.

The cost of cable modems has also dropped to $50, and that is expected to fall closer to $40 by year's end, according to CableLabs chief technology officer David Reed.

The big push now among cable operators is to upgrade to DOCSIS 1.1, which adds quality-of-service and signal priority elements crucial for voice and business services.

Cox chases 1.1

Case in point among operators is Cox Communications Inc., which expects by the end of this quarter to have 100 percent of its voice-dedicated cable modem termination systems upgraded to DOCSIS 1.1, according to vice president of data engineering Jay Rolls.

More than half of Cox's units are now operating in DOCSIS 1.1 mode, and the remainder should be ready to make the transition by the end of this quarter.

On the subscriber side, more than 75 percent of Cox cable modems are capable of supporting DOCSIS 1.1, and all but 5 percent of the remainder can be upgraded, Rolls said.

DOCSIS 1.1 has also found applications in commercial service, where a direct fiber link and telco-based access gear are no longer necessarily the rule, Rolls said.

"As we look at this more and more, we are find out a huge percentage of our commercial customers in our systems could be satisfied with two megabits (per second) or less and a DS1 connection or less," he said. "A lot of the time, we have looked at fiber for big commercial connects, but lately we have been looking at the idea there is a lot more we can do with coax for commercial data services."

Also on the horizon is an incorporation of DOCSIS 2.0, which can triple the upstream bandwidth compared to DOCSIS 1.1 and more effectively filter out return-path noise. By the end of the quarter, Cox plans to be buying only DOCSIS 2.0-certified modems, but that doesn't mean the MSO will be immediately turning on that function set.

"For us the jump to 1.1 is much more significant than the migration to 2.0," Rolls said.

2.0 won't be the end

For now, there are no new additions to the DOCSIS family officially on the CableLabs drawing boards, but work to improve the technology is ongoing. "DOCSIS 2.0 is not the last thing you are ever going to see," said Reed.

While future iterations may offer more improvements, the sheer economics of plant upgrades will limit how often cable operators tweak their DOCSIS data plants.

"We have to be very deliberate in the way we are doing things – we have to make sure we are not doing just science projects," Rolls said. "If we kept change it all the time we wouldn't make any money at it."