More news:
Telcos give ADSL a trial spin
Source: Electronic Engineering Times
Electronic Engineering Times via Individual Inc. : Asynchronous digital-sub-scriber-line
(ADSL) trials are in progress at all eight major phone companies in the United States and
most large phone companies worldwide. To date, no installation exceeds 1,000 lines. The
trials assess both technology and market demand, as well as end-to-end
service/application issues.
The leadership in video-on-demand (VOD) movie trials has been largely from European
phone companies, such as Swiss Telecom, Deutsche Telekom, Bezec and BT. All use
some form of 2-Mbit/second MPEG-1 stored video. These trials run now only at
2-Mbit/s ADSL and all use discrete multitone (DMT) for all or part of the trials.
While the DMT technology has performed extremely well in all trials, exhibiting
reliability beyond telco expectations, the VOD market acceptance as an application by
itself has been mixed at best. All these groups are now looking at providing services with
VOD, particularly the fast-Internet application.
Telstra (Australia) has had a very successful 6-Mbit/s MPEG-2 broadcast-TV trial,
deployed in February 1996 in Melbourne. Because of the apparent higher quality of
digital TV over existing analog, ADSL-service acceptance was excellent. Performance of
6-Mbit/s DMT in the field was between 3 km and 4 km, depending on noise conditions.
France Telecom is investigating 8-Mbit/s ATM- delivery ADSL with two 4-Mbit/s
MPEG-2 TV signals, and has just deployed the trial. Results are not yet available. Italtel
spearheads the European Amuse project, which offers 4-Mbit/s MPEG-2 VOD and
broadcast television-a largely successful trial so far.
GTE has been the leader in an early field trial of fast Internet service with ADSL at two
speeds, 1.6 Mbits/s down and 160 kbits/s up, as well as 4 Mbits/s down and 384 kbits/s
up. While early test results are impressive, local caches with large local content extracted
from the most-hit sites on the WWW are being tested, and allow for the full bandwidth of
ADSL to be evident.
The ANSI/ETSI ADSL standard uses DMT technology patented, by Stanford University
and Amati Communications Corp. The selection of DMT technology imposes an
obligation of equitable and fair licensing on Amati (which also acts as a licensing agent for
Stanford's DMT patents), Existing licensees include Motorola, NEC, Texas Instruments
and Northern Telecom, as well as the customers of their equipment, which is a large list.
V (for Very-high) DSL is an offspring of ADSL, with yet higher speeds over shorter
distances with fiber, bringing broadband signals within 3,000 feet of the customer, and
twisted pair carrying 25- to 50-Mbit/s service the rest of the way.
Copyright 1997 CMP Media Inc.
<<Electronic Engineering Times -- 01-20-97, p. 56>>
[01-22-97 at 17:13 EST, Copyright 1997, CMP Publications, Inc.]
Contact: Electronic Engineering Times |
