(Nikkei BP Group)
(No.1 High Tech News Site in Japanese)
| NTT Readies Optical Fiber Network for Connection to Homes
July 27, 1998 (TOKYO) -- Nippon Telegraph and Telephone Corp. (NTT) outlined
its implementation schedule of fiber-to-the-home (FTTH), which will
start between 2001 and 2002, at the earliest.
|NTT is responding to demands of residential users for earlier and more
inexpensive optical networks. Their needs for telecommunications services,
such as the Internet, are growing.
The pi System Will Promote FTTH
NTT started implementation of optical fiber links from telephone stations
to poles near each house in Kobe City, Nagoya City and Aomori City in
March 1998. This is called the pi System, and it is the initial step
toward full realization of FTTH.
The pi System is not sufficient to realize full
FTTH, because it uses conventional copper wire telephone lines from
poles to residences (See chart). However, players
in the telecommunications industry hope the pi System will help make
FTTH a reality.
Currently, there has been little progress in introducing FTTH due to
expensive equipment and components of optical fiber systems. In return,
that means there has been no cost reduction of hardware due to delay
in introducing FTTH.
Therefore, the market needs a system for laying and extending optical
fiber cables to points near homes before FTTH can come into high demand.
The pi System was devised for this purpose.
There is an underlying reason for this trend. "A key factor is that costs
for installing optical fiber cables became almost equal to those for
laying copper wires in late-1997," said Akira Hirooka, Optical Access
Network Project Manager of NTT Access Network Systems Laboratories.
He means NTT can also save costs by installing optical fiber cables that
have longer life and are less costly compared with copper wires, which
might be replaced after 11 years.
The pi System has a system configuration that enables the sharing of
telecommunications equipment among more than one subscriber, which turns
out to be a major reason for cost reduction in installation. The system
configuration is called passive double star (PDS). It allows 128 subscribers
to share one system.
According to some industry estimates, NTT will have installed pi Systems
equivalent to 4-5 million circuits by fiscal 2000. NTT has not revealed
In this deployment, almost 3 million circuits will be constructed every
year after fiscal 2000. The massive implementation is expected then
to gradually bring about a downward trend in prices of telecommunications
equipment and components for optical fiber transmission.
Authentic FTTH Under Development by Manufacturers
If a home user requests an extension of an optical fiber cable to his
or her residential premise, it can be fulfilled as long as the pi System
reaches a pole near that home. But only 10 percent of users now connected
to all the circuits can enjoy FTTH services based on the pi System.
Therefore, so-called "authentic" FTTH is being addressed by manufacturers
of telecommunications equipment and optical fibers, meaning that all
the households will have a direct optical fiber connection.
For example, installation costs of FTTH will be reduced to the level
of copper wire installation costs in two to three years, according to
a researcher at Fujitsu Laboratories Ltd.
The costs of FTTH can be brought down to match those of copper wire within
1998 or they can be less expensive in the near future, according to
a researcher at Matsushita Communication Industrial Co., Ltd. The costs
can be reduced along with competition among manufacturers, which would
work favorably for NTT's implementation of FTTH between 2001 to 2002.
There is a consensus among telecommunication equipment manufacturers
on the best system configuration for realizing an authentic FTTH: asynchronous
transfer mode-passive double star (ATM-PDS). ATM-PDS can provide services
for all users in a service area with a transmission rate of a maximum
of 156Mbps. This system can meet the needs required for multimedia services.
However, there are some issues yet to be solved. For instance, current
ATM-related equipment is very expensive, since its sales target is telecommunications
providers and enterprises with a backbone network system. Some speculate
that ATM facilities would cost 1,000 times more than synchronous transfer
mode (STM) telecommunications facilities, which have been introduced
In summary, the market still observes unsettled competition between the
ATM-PDS technology and the synchronous transfer mode-passive double
star (STM-PDS) technology as to which should become the standard system
configuration of FTTH.
Opposition from Domestic Observers to NTT's Policy
NTT and other manufacturers have not yet obtained full support from those
who doubt the success of the scenario for introducing FTTH. It is mainly
because prices are too high to practically use FTTH, and the implementation
schedule is too slow.
It is easy to understand why the prices cannot be lowered. The market-oriented
principle of competition doesn't exist. Moreover, there is no checking
system for NTT's strategy, even if it misses a point.
"The Telecommunications Business Law should be revised so that carriers
other than NTT can provide high-speed services," said Toru Takahashi,
chairman of the Internet Association of Japan.
Another criticism was issued by Takashi Tsutsui of Teikyo University,
who said, "The Japanese government should establish a new law with the
same legal force as U.S. Telecommunication Act of 1996."
NTT plans to complete the full deployment of optical communication systems
by 2005. That will provide a high-speed service with a maximum performance
of 10Mbps based on the pi System. However, there are strong arguments
about whether users can really wait for the service until 2005.
"Asymmetric digital subscriber line (ADSL) technology should be adopted,
as it has been already available for commercial use in the United States,"
said Masataka Ohta of the Computer Center of Tokyo Institute of Technology.
NTT also has been conducting technical validation tests of ADSL, wireless
local loop (WLL) and Multimedia Mobile Access Communication System (MMAC)
for application to telecommunications services for home users.
However, they are still positioned as complements to FTTH.
The only way to respond to naysayers is for NTT to provide inexpensive
high-speed services using FTTH based on ATM-PDS technology.
Hirooka of NTT commented, "FTTH is the best state-of-the-art technology.
No engineers in this field doubt that FTTH can become an ultimate technology
in telecommunications engineering."
Chart: Three Methods to Realize Full Optical Fiber Communication Systems
NTT's expression, "the realization of optical fiber communication systems
in access networks,"
doesn't simply mean realization of FTTH.
also includes both the central terminal and remote terminal (CT/RT)
as well as the pi System to the category of the realization
of optical fiber communication systems.
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