NTT to Launch xDSL Field Test in Feb. '98 (CAP too)
December 30, 1997 (TOKYO) - NTT Corp. will field test digital subscriber lines
(xDSL) from February to December 1998, company officials said.
NTT will invite its general users and Internet service providers other than its own
Open Communications Network service to participate in the field test as monitors.
The company will provide them with high-speed Internet access of a maximum of
9Mbps.
The xDSL is a modem technology that uses telephone copper wire for high-speed
communications. Both asymmetric digital subscriber line (ADSL) and symmetric
digital subscriber line (SDSL) will be tested.
With ADSL technology, the upstream and downstream speeds are asymmetrical,
with some products' transmission speeds reaching about 9Mbps. The upstream and
downstream speeds are symmetrical in SDSL technology, with a maximum
transmission speed of 2Mbps each.
An xDSL modem set up at a user's home and an NTT station will enable customers
to use a copper wire cable as a high-speed access line. With the xDSL modem linked
to a telephone set, users can also use the telephone and access the Internet at the
same time.
NTT has been testing xDSL at its research laboratory. The test results has so far
proved: (1) integrated services digital network lines affect and slow the transmission
speed of an ADSL line, (2) users located further away from NTT stations cannot
communicate via an xDSL line, and (3) the transmission speed is influenced by
diameter, age and insulation of a telephone cable.
"We would like to find out what conditions we should set on an xDSL line to offer it
as a commercial service and how users will evaluate it, and then decide if we will
commercialize the service or not," said Masamichi Sakamoto, senior manager of
NTT"s network strategy planning department.
The field test will cover Tokyo's 23 wards, including Kunitachi and Chofu in Tokyo,
Yokohama in Kanagawa Prefecture, Matsudo and Abiko in Chiba Prefecture, Tsukuba
in Ibaraki Prefecture and Osaka.
The test areas were selected to have a variety of diameters and ages of telephone
cables laid in those wards and cities to collect data taken in various environments.
The degrees to which ISDN lines are clustered in the selected wards and cities also
vary.
The xDSL modems using several methods from several manufacturers will be used for
the test. The two types of xDSL technology, carrierless amplitude/phase modulation
and discrete multi tone, will be both tested. NTT also is considering testing the
transmission of asynchronous transfer mode data over an ADSL line.
The access fee for xDSL will be free during the field test. For the test, NTT will lend
xDSL modems to users. The access fee for the Internet connection will be set by
Internet service providers including NTT. The test fee is likely to be lower than the
regular fee.
Information such as Internet connection fees for the test, choices of speeds and
providers in each ward and city is likely to be disclosed in mid January 1998.
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