Cable Modems, DSLs Continue To Vie For Home Access
(02/01/98; 12:21 p.m. EST)
By Craig Matsumoto, EE Times
With a clear winner yet to emerge in the broadband-access battle, proponents of digital subscriber line services (DSLs) and of cable modems have respectively been pitching the superiority of the technologies for providing high-speed data connectivity to the home. At "Broadband Residential Access: When, How, and For What?" a DesignCon98 panel, both sides stated their case and agreed that, for the short term, DSLs and cable modems can split the available market.
Asymmetric DSL , which allows the downloading of data at 8 Mbits per second and uploading at 640 Kbits per second, was a promising technology five years ago, but regional telephone companies have been slow to deploy it. That's left an opening that cable TV companies have exploited with a "cowboy" mentality, said panelist Gary Law, vice president of marketing of Terayon. In contrast to the deliberate moves of the telcos, cable companies dove into the deployment of cable modems and have been honing the service continually.
But the DSL side got a boost earlier this week when Intel, Compaq Computer, and Microsoft jointly announced support for "splitterless" ADSL standards. "It was just diverging. There were so many companies promising so much," said Dan Cordingley, a director of marketing for Level One Communications.
Cordingley was one of two participants representing the DSL camp on the panel. The other was Michael Henderson, who heads DSL services marketing for Rockwell Semiconductor Systems. Henderson extolled the virtues of splitterless ADSL set-ups, which he said lower costs and simplify installation by eliminating the in-home box that divides incoming signals between data and voice. Splitterless ADSL downloads data at only 1 Mbit per second, but that's about the current maximum for PC-Internet connections anyway, Henderson said.
In addition, splitterless ADSL modems could be offered for about $200. That cost is low enough to be a retail play. "What we'd like to see is another modem -- a 1-megabyte modem -- go into your store," Henderson said.
As for the flavors of ADSL that are already being implemented, Henderson declared carrierless amplitude/phase modulation (CAP) to be "dead and buried." He also expressed doubts about DSL using 2B1Q line codes due to their emphasis on symmetric services -- wherein download and upload speeds match. Henderson didn't see symmetric services becoming an immediate factor in home use. Cordingley, on the other hand, advocated a need for symmetric home access in some cases.
"Do you want to use [all that bandwidth] for one application?" he said. "You probably would like some symmetry for videoconferencing, for telecommuting." As evidence, he pointed out that ADSL work is leaning toward symmetrical service -- the initial ADSL has a 10-1 download-to-upload bandwidth ratio, while G.Lite specifications drop the ratio to 2-1, he said. For applications needing that robustness, Cordingley suggested options such as high-bit-rate DSL and HDSL-2.
Customers waiting for high-bandwidth services are in the minority, but they're anxious for service right away. "What people care about, and who gets the business in the short term, is [determined by] who gets there first," Terayon's Law said. In the long run, issues such as the quality of each service will come into play.
Both DSLs and cable modems play off existing infrastructures -- telephone lines and cable TV -- and panelists conceded that the current market for high-bandwidth service is tiny. But each has a chance to make its mark fairly quickly with early adopters, panelists said. "Both are able to coexist, so I think they will end up serving different marketplaces over time," Law said.
Closing the panel's comments, however, professor emeritus Martin Graham of the University of California noted that these high-speed services won't completely live up to their hype. Because testing is being done in labs, and not on the copper and coaxial lines in the real world, Graham predicted that factors such as impulse noise and nearby radio stations will dilute the available bandwidth.
"I'd expect that when all this stuff is implemented, it won't work as well as expected," he said. "I'm not sure that the testing is adequate."
Given that problem, Graham wondered aloud if consumers should have recourse for high-bandwidth services that fail to provide high bandwidth. "Maybe they ought to enact a 'Lemon Law' in the communications business," he said.
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