Education & Distance Learning Enthusiasts- Doin' the pachyderm shuffle - telephone companies utilize digital subscriber line technology

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Doin' the pachyderm shuffle - telephone companies utilize digital subscriber line technology

Telephony - September 2, 1996

Cable modem mice tempt telcos onto the data dance floor

Digital subscriber line technology, fueled by another phenomenon - the Internet - is experiencing an unprecedented heyday. DSL revenues are expected to reach $2.5 billion, and shipments are expected to reach 12.5 million units by 2000 - a compound annual growth rate of 166% for revenue and 298% for shipments, according to a report released last week by Dataquest, San Jose.

The report, titled "Inviting the Elephants to Dance," compares telcos with elephants struggling to learn the data dance. "Like the proverbial mouse that scares the elephant, cable companies have stampeded the telephone companies on to the dance floor" by preparing to roll out high-speed cable modems, transforming their service into two-way transmission, it says.

"Cable modems and DSL will both be successful. Users are demanding the speed," says Lisa Pelgrim, industry analyst and author of the report. "The Internet is just the beginning."

The technology will provide the last mile pipe to the home for telecommuting, videoconferencing, video phones, interactive gaming and distance learning, the study says. The latest developments center on asymmetrical digital subscriber line because it is more mature and readily available than some other forms of DSL technology.

While telcos race to make the most of their copper wire infrastructure with DSL, six groups are debating technical issues surrounding the technology (see box).

"Everyone has recognized there is a tremendous market for the application of these technologies," says Tom Starr, chairman of the T-1/E-1.413 working group and a senior member of Ameritech's technical staff. "All these groups are working together in a cooperative, effective manner."

Still, CAP supporters are lobbying to standardize the modulation scheme (Telephony, July 29, page 6).

Discrete multitone (DMT), though not as old as CAP, was picked as the standard format for ADSL technology by Bellcore in 1993. Two years later, ANSI's T-1.413 subcommittee issued details on implementing the DMT standard, says Tac Berry, vice president of marketing at Amati, the company that developed DMT with Stanford University in 1992.

CAP and DMT are not compatible. ANSI chose DMT "because at the time it had better rate adaptation, and ADSL was considered a future technology whose primary application would be video," the Dataquest study says. The interactive TV market has since been dwarfed by the Internet.

Now, supporters of both CAP and DMT want their respective line code to become the international standard, says Richard Stuart, chairman of an ITU committee that has been studying high-speed modems. The ITU will hold its plenary session in Geneva, Switzerland, in October, where it will redistribute study topics among its committees. One topic certain to be assigned is high-speed data communications on the local loop.

Of the other groups, ANSI focuses on ADSL line code standards, while the ADSL Forum looks at the technology as an end-to-end system used to offer services, said Kamran Sistanezadek, director of architecture at Bell Atlantic. He is a member of the ADSL Forum's board of directors.

The ADSL Forum is more interested in what the DSL modems carry, like Internet traffic or asynchronous transfer mode cells, Sistanezadek says. Essentially, the forum promotes copper access for broadband applications and supports DMT and CAP.

The DMT interoperability group will focus solely on the interoperability of DMT-based ADSL access products. The group's second meeting is scheduled this week in Chicago - the same week ANSI's T-1/E-1 group convenes.

The DMT group will test product interoperability at the network interface level, says James Szeliga, general manager, Orckit Communications, a Shelton, Conn.-based access equipment maker. While the group has not started its "discovery testing" yet, its mission seems very similar to the ISDN interoperability testing sponsored by the California ISDN Users Forum. The CIUF's test sessions are commonly referred to as ISDN "bake-offs" because vendors can test their products' interoperability on a variety of levels behind closed doors.

The CAP interoperability group's focus varies from the focus of its DMT rivals, though the names are analogous.

The CAP group was created to write the specification brought before the last ANSI meeting in July.

Whatever the standards rulings, telcos and tariffs will determine DSL's success, Dataquest's Pelgrim says. To be competitive, monthly fees for DSL services should be less than $50 for consumers, her report says, adding, "These elephants have been invited to the data dance, but only time will tell whether they can be quick enough on their feet to stave off the competition."

DECIDING DSL'S FATE

* ANSI's Committee T1

* ITU Study Group

* ADSL Forum

* DMT Interoperability Group

* CAP Interoperability Group

News Editor Sandra Guy contributed to this story

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