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Technology Stocks : COM21 (CMTO) -- Ignore unavailable to you. Want to Upgrade?

To: Peppe who wrote (412)	5/24/1999 2:53:00 PM
From: OverSold	Read Replies (3) \| Respond to of 2347

This will help CMTO and cable in general. To print: Select File and then Print from your browser's menu -------------------------------------------------------------- This story was printed from ZDNN, located at zdnet.com. -------------------------------------------------------------- Standards may stymie DSL push By Carol Wilson, Inter@ctive Week May 24, 1999 7:00 AM PT URL: zdnet.com Competitive local exchange carriers have been aggressively putting Digital Subscriber Line technology into the local network to offer faster data services, but their future efforts could be affected or even hampered by a federally mandated industry drive to develop standards for offering DSL and other new services over the public telephone network. A working group with Committee T1, the accredited telecommunications standards body for the U.S., will meet in Ottawa, June 7-11 to try and finalize a draft standard of rules by which DSL and other high-speed services can be offered. Particularly at issue is Symmetric DSL at speeds above 768 kilobits per second, because there is concern that a proliferation of SDSL-based services at the higher speeds could disrupt existing services, including voice, T1 (1.5 megabit-per-second), Asymmetric DSL (ADSL) and even other SDSL lines. Higher-speed SDSL has been a popular competitive local exchange carrier (CLEC) offering with small and midsized businesses, because it provides faster data access service much less expensively than T1 service. Businesses are more interested in SDSL, because the bandwidth is high-speed in both directions, while ADSL, which most incumbents are offering, delivers high-speed downloads and slower upload speeds. But the growing popularity of SDSL could be its undoing. "It's a problem that will hit us all in the head with a two by four," said Frank Wiener, vice president and general manager of the DSL access products division at Paradyne. Too much interference The problem affects SDSL services that use a line code developed for Integrated Services Digital Network known as 2B1Q but use more signal power to transmit at higher speeds. Those 2B1Q-based services use echo cancellation, because the transmit and receive signals occur in the same frequencies. But echo cancellation can't prevent interference between multiple SDSL services provided over different lines in the same binder group, or cable bundle, nor can it keep higher-power SDSL from interfering with voice or other services. "SDSL is a service that operates at a multiplicity of bit rates, and we've agreed on a number of those, at 768 Kbps and below," said Tom Starr, Ameritech's representative to the working group involved, T1E1.4, and its chairman. "There are still issues to be resolved for SDSL above 768 [Kbps]." Jeff Blumenfeld, general counsel for Rhythms NetConnections, which with Covad Communications and NorthPoint Communications has been offering SDSL in national network buildouts, thinks most of the real issues are political. "We've been conducting an interesting lab experiment in California, with four service providers [Covad, NorthPoint, Pacific Bell and Rhythms], six equipment providers and five to eight varieties of DSL being offered," he said. "Nobody has found a single problem. The focus is on SDSL that is faster than 768 Kbps - well the incumbent telephone company's ADSL can only do 768 symmetric service. It's such a clear conflict."