Kahaner Report: NTT R&D plans (1994). part 1 of 2

[David Farber <farber () central cis upenn edu>]

From:
 Dr. David K. Kahaner
 US Office of Naval Research Asia


ABSTRACT. NTT's R&D plans (1994).


This article, written by Noboru Miyawaki, Executive VP, Senior Executive
Manager, NTT Research & Development Headquarters, was published in the
NTT Review, Vol 6, No. 3 May 1994.


In analyzing this report, readers should compare the (quite) similar
remarks made in the report "hitachi.94" 8 Oct 1994.


        NTT REVIEW Vol 6, No. 3 May 1994


OVERVIEW OF NTT'S R&D


Noboru Miyawaki


With the ever-increasing importance of high-speed information in society
as we move towards the next century, NTT is pressing forward with
research and development aimed at implementing its VI&P (Visual,
Intelligent and Personal) services and the construction of a new network
to support them.  In regards to the former, based on a long-term view of
technological and market trends, NTT is researching and developing
services that will make possible an effective progression from the
development of services that answer to potential needs towards the
full-scale implementation of VI&P services.  In regards to the latter,
we are responding in a flexible manner to the increasing deversity and
dispersal of the communications environment by separating the network
into a transmission system and a versatile information
control/conversion system, and enhancing the performance of both.
Within these broad aims, we are currently focusing our attention on
three areas:  the technology for a high-speed broadband transmission
system featuring optical frequency multiplexing and ATM techniques,
network and software technologies for advanced information control and
conversion, and technology for constructing a new access network that
can provide a comprehensive range of multimedia services.


This article describes our concept of how VI&P services will develop in
the future, and the latest trends in the field of communications.  It
also describes the ideal configuration of the new network and discusses
the important technological aspects of how it is to be constructed.
Finally, it presents the results of our recent research, which includes
some innovative work, and points out the areas requiring future
investigation.




INTRODUCTION


As the world stands poised at the beginning of a new millennium, a tide
of change is sweeping through many areas.  Telecommunications is no
exception -- indeed, this is a field which is being driven by fierce
trends towards diversity and distribution, and in which technical
innovation holds the key to its revolution.  These trends have a
decisive effect both on the way in which new networks are introduced and
on future technological trends.  Furthermore, technological innovation
is becoming a matter of utmost importance to communications carriers who
are now being drawn into all-out competition with each other.  NTT is
currently facing unprecedented challenges as a result of the prolonged
economic recession and intensified market share competition.  However,
in spite of these circumstances, we are also putting increased effort
into our continuous pursuit of R&D based on a long-term perspective.


NTT's primary R&D mission is to make technological developments and
innovative advances while maintaining sufficient flexibility to respond
to any developments in information networks.  For this reason, we are
taking a broad view of the way in which new networks should be
introduced.  While providing sufficient physical performance such as
high speed and wide bandwidth, it is also important to supply new
services having potential needs and to respond quickly to a multitude of
existing needs.  Consequently, we are researching and developing the
essential technologies, both hardware and software, with the overall aim
of achieving "high speed" in all senses of the word.  And as the
foundation for technology that will revolutionize these information
networks, NTT is involved in wide-ranging research of both innovative
and fundamental areas.  Furthermore, another of NTT's R&D missions is to
make the results of our basic research available for scientific,
technological, and social development world-wide.


This document describes the targets of NTT's main R&D fields, and the
key technologies required to achieve them.  It also discusses the
approaches that should be taken, and the likely effects on society as a
whole.




1.  NTT's VI&P Vision and New Trends in Telecommunication


The present-day communications environment (see Fig.1) is having rapid
and dynamic effects on society, economics and culture.  This is
reflected in the progress being made by ATM technology and high-speed
LANs, the development of high-speed computer links, the rapid appearance
of multimedia technology in personal communications devices, and the
fusion of communications and broadcasting in "Video on Demand" services
(particularly in the U.S.) to give but a few examples.  With field
trials of next-generation communications services scheduled to begin in
1994, the conception of the "Information Super-Highway" in the U.S. and
the "Next-Generation Communication Network" in Japan, plans for
global-scale portable phone networks using satellite technology, and the
active internationalization of communications carriers in all countries,
the above trends are growing to influence behavior not only at the
national level, but also on a worldwide scale.


[Figure 1 is omitted. It shows the overlapping orbits of communications
services, broadcasting services, and computer technology and services.
Multimedia seems to be at the center, but all the usual topics are
listed as well.]


Major trends such as these are helping to clarify the routes by which
VI&P services will be implemented, and are accelerating the
communications revolution.  In the future, competition for the
development of fundamental technologies and ongoing development of
applications in joint testing programs should lead to expanded media,
faster and easier information processing, and improved mobility of
communications services.  It is important to establish promptly a
service image that is directly related to these developments.


2.  Network Evolution and Key Technologies


A prerequisite for the expansion of future multimedia services is the
construction of networks that can effectively and flexibly utilize the
wide bandwidth of optical fibers in in order to cope with a quantum leap
in data transmission rates.  For this purpose, NTT is working at
converting to digital networks and B-ISDN, enhancing intelligent
functions, and introducing optical fiber into the access network, as
shown in Fig. 2 [omitted. This is a time-line of movement from analog to
N-ISDN to B-ISDN, with 100% B-ISDN by 2015].  This move towards
digitization is not merely driven by consumer demand, and we plan to
have finished it by 1997.  By 2015, we will have constructed an
extensive network that can communicate video, speech, data and other
multimedia information at ultra-high speeds with the sense of "being
there."  To achieve this, it is essential to make further advances in
optical frequency multiplexing and ATM switching technology, and to
improve the performance of service software.  We have already
established fully-optical trunk lines between the major cities of Japan,
and we are proceeding with strategic conversion from metallic wire to
optical fiber within the cities themselves, starting with central Tokyo
and then moving on to greater Tokyo, Osaka, Nagoya, and other cities
designated by the government.  By 2015, we expect to be able to offer
VI&P services to every household.  Such "fiber- to-the-home" (FTTH)
services presume the existence of a fiber-optic access network.  This
will be achieved by developing systems to respond to the scale and
temperament of the market, constructing an access platform to support a
complete range of services, and maximizing the efficiency and
reliability of each system.  Our research and development will cover all
these areas.


The following section outlines the chief technologies required for the
transport layer, access network and intelligent layer, and the efforts
NTT is making in leading-edge basic research to contribute to these
innovations.  It also discusses the progress of our VI&P experiments
incorporating the very latest B-ISDN technologies, and the way in which
future networks will be introduced.




3.  Transport Layer


For the construction of the B-ISDN, new technological breakthroughs must
be made in switching and transmission systems.  This section describes
NTT's targets and achievements already made in the technologies for
optical switching and high-speed optical transmission in the transport
layer.


3-1 Optical switching Technology


As optical communication becomes more widespread, more and more users
will require increasingly vast amounts of information to be transmitted.
In order to achieve our long-term goal of providing a 150-Mbit/s VI&P
service to every household, it will become essential to use "optical"
nodes, in which switching is done directly on the optical signals.
Consequently, one of the most important breakthroughs clearning the way
for B-ISDN is the development of an all-optical ATM switch with a
throughput on the order of terabits per second.


Figure 3 [omitted] shows the progression of optical switching
technologies [from 1993 (at about 40Gbit/s using large-scale switching
LSI's), to early 200x (with optically-interconnected switches) to 2010
with photonic switches)].  The keys to development are advances in VLSI
and optical interconnection technologies, and the development of
photonic switching.  Throughputs of 40 Gbit/s are currently available,
these being achieved in systems that incorporate densely-packed
high-speed LSIs, enabling them to operate at maximum speed.  These
systems are already at the stage of overall system trials.  It is likely
that the capacity of board-mountable switches will become much higher
through advances in VLSI technology.  As the throughput increases, a
bottleneck is first likely to occur in the interconnections between
boards due to the limitations of electronic technology.  However, this
problem can be resolved by exploiting the wide bandwidth available for
optical signals by means of high-density optical waveguides.  That is,
the firstventures into the terabit realm will be made by optically-
interconnected ATM switches.  By converting the switching elements
themselves over to all-optical devices, throughputs in the region of 100
Tbit/s will become possible in the future.  We are vigorously
investigating ways of achieving closer fusion between spatial-division,
time-division and frequency-division techniques that make full use of
light's inherently wide bandwidth, high speed and parallel capabilities.


3-2  High-Speed Optical Transmission Technologies


With the aim of establishing an all fiber-optic network, NTT is
continuing its installation of fiber-optic technologies into
transmission systems.  The progress made so far by optical transmission
technologies is shown in Fig. 4 [from the early 1980s to about 2005,
with optical transmission capability increasing from about 100Mbit/s
(using 1.3mu-m single-mode optical fibers) through 10Gbit/s in 1996-7
(using optical fiber amps), to 100Gbit/s (using ultrafast optical signal
processing, lightwave communications, and optical soliton
transmission)].  Higher speed and greater capacity have been achieved
through the use of new technologies such as single-mode optical fibers,
semiconductor lasers and optical fiber amplifiers.  In addition, these
technologies have contributed to a dramatic fall in the cost of
communications.  In the future, new technology will contribute to
reducing the cost factors associated with distance and speed, making
communications more economical.  NTT's all-optical network will not only
be characterized by such fundamental benchmarks as these, but also by
simplicity of construction and flexibility of the services it provides.


Key technologies for all-optical systems will include optical frequency
multiplexing, optical soliton transmission and ultra-high-speed optical
signal processing.  Here, we will introduce the results of the latest
research in these fields.


Optical frequency multiplexing is a means of transmitting multiple
optical signals through one strand of optical fiber at different
wave-lengths.  It is currently possible to transmit 128 different
wavelengths of light over long distances without using repeaters.
Optical soliton transmission is a technique that simultaneously resolves
the effects of both the bandwidth restrictions and the non-linearity of
optical fibers, and is being vigorously researched all over the world.
At NTT, we have performed successful trial transmissions of 20 Gbit/s
over 1,020 km without penalty using optical fiber amps as repeaters, and
this technology seems to be ideal for achieving long-distance
communications over thousands of kilometers without the use of
repeaters.  Furthermore, we have developed ultra-fast signal processing
technology that makes it possible to transmit a 100-Gbit/s optical
signal by optically multiplexing 16 different 6.3-Gbit/s signals
together, and then separating them again.  These results offer the
potential of raising the technological level across the board, with
ultrashort optical pulse generators, optical signal multiplexers and
demultiplexers, optical timing extraction circuits, and so on.  The
above are examples of the special features of optical transmission by
building upon serious investments in advanced technologies and breading
new groud.


4.  Fiber-Optic Access Network


In order to offer the multimedia services envisioned for FTTH, the
construction of an advanced access network is indispensable.  If a
reasonably-priced, user-friendly access system can be constructed and
acceptable services introduced, it is expected that potential market
needs will be awakened leading to a synergetic and rapid development of