DOCSIS 2.0 Targets Upstream Upgrade

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Cable Television Laboratories Inc. has unveiled plans to turn the cable Internet's dirt back road into a four-lane highway with guard rails to better carry voice and symmetric business data.

Data Over Cable Service Interface Specification 2.0 will used advanced physical-layer technology to boost bandwidth and ease upstream signal interference for cable-modem systems. CableLabs expects to finalize the specification by the end of the year, with interoperability tests and certification waves targeted for 2002.

Improving the path for data traveling from the cable-modem user to the central cable network has not been a significant issue for residential data-over-cable service. But it's seen as critical if cable operators want to branch into business offerings that require more symmetric throughput to carry voice and Web server traffic.

Using two scheme options — synchronous code-division multiple access modulation (S-CDMA) and advanced frequency agile time-division multiple access (A-TDMA) — DOCSIS 2.0 promises to boost upstream bandwidth 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 chronic signal-interference problems.

The technology will also be compatible with DOCSIS 1.0 and 1.1, so cable operators won't have to swap out entire cable-modem systems, said Rouzbeh Yassini, an executive consultant who is overseeing the cable modem initiative at CableLabs.

Cable operators can install upgrade line cards on existing cable-modem termination systems or buy units configured for 2.0. Either way, the controllers would still support modems on the older DOCSIS 1.0 and 1.1 schemes. Users would require 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 flawlessly."

At a time when operators must be mindful of their pocketbooks, DOCSIS 2.0 will provide a relatively inexpensive way to create a business-oriented service.

"We're trying to get to symmetrical services here," Yassini said. Compared to alternatives such as direct fiber links, "this technology will give them the best fixed cost price on the upstream channel."

The fact S-CDMA was chosen as one of the schemes for an advanced physical layer specification was good news for cable equipment maker Terayon Communication Systems Inc. The company started work on S-CDMA technology in 1994, and since then it has deployed some 1.8 million cable modems with its own proprietary S-CDMA technology. Terayon's stock got a big lift on relatively heavy volume early last week.

"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," said Rich Prodan, Terayon's senior vice president and chief scientist. "If Terayon would only get 20-percent market share worldwide, it's huge compared to 100 percent of the proprietary market that we now enjoy."

The news also boosted startup Pacific Broadband Communications, which is preparing to enter the CMTS market with a unit powered by a home-grown chipset. The San Jose, Calif.-based company has been among those vendors working with CableLabs on the advanced PHY technology, and has announced plans to have a DOCSIS 2.0-compliant CMTS using A-TDMA ready for market shortly after the standard is finalized in the fourth quarter. The quick turnaround was possible because of that work and the fact the company can adapt its own chip more quickly, according to vice president of strategic marketing Tom Fong.

"We do have an advantage compared with our competitors, because we have been working very closely with CableLabs and we have a very good understanding of the technology," Fong said. "I would say we are six to nine months ahead of our competitors."

DOCSIS 2.0 is a necessary development for the cable industry, which needs to upgrade the technology to stay competitive, he added.

"Actually, it is about time, because if you look at the DSL [digital subscriber line] technology, it has always been evolving," said Fong. "They had ADSL [asynchronous DSL], and then people talked about VDSL [very-high-speed DSL] and other types of high-speed DSL technology. Operators should always be looking for new technologies to send more bits to each home."

CableLabs is also nearing the end of a certification round for DOCSIS 1.1 modems later this month. Thus far, there have been no modems certified for 1.1, which adds the 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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