Telcos expressed cautious optimism last week that they
would be able to begin offering digital-subscriber-line services based on the
just-completed "plug-and-play" G.Lite standard by mid to late 1999.
Industry consensus on specifications for the standard has
moved very quickly, but the rollout schedule for the technology is lagging behind what
vendors were predicting a year ago, when they said G.Lite could be in stores as early as
this Christmas.
But the rapid approval and worldwide breadth of support for
the new standard suggested that the service could roll out rapidly.
Initial testing of G.Lite, which is also known as
"ADSL.Lite" (for asymmetrical DSL), has begun in several telco territories,
including trials by GTE Corp. in Portland, Ore., and by BellSouth Corp. at the campuses of
the University of Florida in Gainesville and the University of Miami.
So far, test participants said, vendor systems have
demonstrated that the standard works as billed. Carriers are delivering data at rates of
1.5 megabits per second downstream and 512 kilobits per second upstream, together with
analog voice over existing outside plant and in-home wiring from central offices as much
as 15,000 feet away from end-users.
"We've been operating the test to a cluster of 20
users, representing a wide range of home-wiring and outside-plant conditions, for about 30
days," said Bev White, program manager for new-product development at GTE.
The test, involving employees of Intel Corp., encompasses
new and old homes, some with wiring that has been in place for more than 50 years, White
said.
In nearly all cases, data and voice signals operating
simultaneously over single twisted-pair wiring have met performance specifications, she
said. Where performance was subpar due to interference between simultaneous uses, an
easily installed microfilter on one or more telephones solved the problem.
Attendees at an International Telecommunications Union
conference two weeks ago agreed to present the standard for the G.Lite specs, which are
designed to overcome the drawbacks of existing ADSL systems.
One problem is the requirement that a second line must be
installed to carry data to the personal computer from a premises-mounted splitter that
connects with the outside line.
Full-rate ADSL systems are designed to operate at
downstream speeds of as high as 8 mbps, depending on user distance from the CO. The G.Lite
system is not only capped at 1.5 mbps, but it is also built to throttle down to a few
hundred kbps when the data link and phone circuit are in operation at the same time.
"With no phone off the hook, even the users at the
outer distances [from the CO] are getting the full rate," White said. "And when
phones are off the hook, in many cases, we're seeing data rates as high as 480 kbps
downstream and 220 kbps upstream."
The next phase of the GTE test, expanding to about 50
users, will seek to demonstrate that customers can easily install the G.Lite service
without requiring visits by technicians, which is another key goal of the standard.
Despite the early positive results, GTE and other telcos
made it clear that they are not going to rush the implementation of G.Lite. Instead, they
will continue expanding their market bases using the ADSL systems that they have put in
place, while waiting for the manufacturing, interoperability and retail-distribution
pieces to fall into place for G.Lite.
Where things will move quickly is on the customer-equipment
front, said Bill McDonald, a senior product manager at Fujitsu Network Communications
Inc., which is partnered with Orckit Communications Ltd. as a supplier of ADSL gear to
GTE.
"I think that you'll see some modem suppliers bringing
equipment to market very soon that operates at 56 [kbps] and that comes with G.Lite
functionality that can be implemented later on with a software upgrade," he said.
Orckit -- which supplies core silicon, as well as complete
ADSL-system components -- is in negotiations with a number of potential OEM
(original-equipment manufacturer) customers in preparations for introducing modems into
the retail-distribution chain "in the next few months," said Bill Dorsey,
strategic marketing manager for Orckit.
But first, these manufacturers will have to test their
devices for interoperability with Orckit's and other vendors' G.Lite CO gear, he added.
So far, no formal means of interoperability certification
has been established for G.Lite along the lines of the cable industry's DOCSIS (Data Over
Cable Service/Interoperability Specification) process.
Bell Communications Research (Bellcore) is about to convene
a G.Lite certification process, and it is also likely that the ITU and the U.S.-based ADSL
Forum will implement such procedures, McDonald said.
GTE will be able to upgrade its DSLAMs (DSL-access
multiplexers) via software, without having to add new hardware, White noted. Likewise,
telcos using DSLAMs supplied by Alcatel Alsthom's Alcatel Telecom unit -- including
BellSouth, Ameritech Corp. and SBC Communications Inc. -- will be able to upgrade to
G.Lite via software, said Jay Fausch, senior director of marketing and business
development at Alcatel.
Fausch added that Alcatel has already taken steps to
achieve interoperability both at the chip level, in conjunction with an agreement with
Texas Instruments Inc., and at the end-user level, in testing with a variety of modem
suppliers.
"Hundreds of lines are running G.Lite in the
University of Florida trial, and it has gone very smoothly," Fausch said.
Even so, Fausch, like other industry players, acknowledged
that the pace of industry rollout of G.Lite services will be relatively slow, pending
wider interoperability testing and broad support at the consumer-product end of the
market.
