NTT Technical Review
October 2011 Vol. 9 No. 10
View from the Top
Hiromichi Shinohara
NTT Senior Vice President,
Director of Research and Development Planning Department

Front-line Researchers
Hiroshi Yamaguchi
Senior Distinguished Researcher
NTT Basic Research Laboratories

Feature Articles: Collaborations with Universities
Leading to Open Innovation in NTT’s R&D
Efforts Toward Organizational University Collaborations
Room-temperature Resonant-tunneling-diodeTerahertz Oscillator Based on Precisely Controlled
Semiconductor Epitaxial Growth Technology
Automatic Generation of English Cloze Questions
Based on Machine Learning
High-presence Audio Live Distribution Trial
CMOS LSI for Brain-machine Interface Used in
Bidirectional Communication
High-quality Software Development Through Collaborations
with Major Universities in China
Secure Method of Managing Digital Content in
Ubiquitous Computing Environment
Joint Research on Anshin in Internet Usage

Regular Articles
Stripping-free Physical-contact Connector
Optical Power Budget Enhancement Technologies forLong-reach GE-PON System

Global Standardization Activities
Trends of International Standardization ofThree-dimensional Video CodingPractical Field Information about
Telecommunication Technologies
Case Studies of Failures of Business Phones
Connected to VoIP Gateway

External Awards/Papers Published inTechnical Journals and Conference Proceedings
External Awards/Papers Published inTechnical Journals and Conference Proceedings

View from the Top

Ask Not What Can Be Done but What
Should Be Done—True Achievement
Is Not Just Creating New Businessbut Clarifying One’s Role in R&D
Hiromichi Shinohara
NTT Senior Vice President,
Director of Research andDevelopment Planning Department
Overview

In the wake of the Great Eastern Japan Earthquake of 2011, the importance of the network has been reaffirmed. What, then, does society expectof the NTT Group as a carrier that includes research laboratories? We asked
Hiromichi Shinohara, NTT Senior Vice President and Director of the
Research and Development Planning Department, to tell us about the stancethat researchers should take against the backdrop of a rapidly advancing
mergers-and-acquisitions business environment extending across national
borders.

Following an unprecedented earthquake,Japan takes on the urgent task of developing
network services that are more robust to disaster—Mr. Shinohara, please tell us about the environmentthat currently surrounds R&D at NTT.
The Great Eastern Japan Earthquake has certainly
forced us to rethink many things. It had always been
our intention to construct a highly reliable, robust
network, but upon objectively evaluating the damage
caused by this earthquake, we could see that there areareas where our efforts have come up short. In particular, the effects of this disaster have made us
keenly aware of how much our network depends onelectricity. Our primary goal, therefore, should be toconstruct a network that is less dependent on commercial power supplies.
At the same time, we should look at the changes
that occurred in the makeup of NTT revenues in the2000 fiscal year. Up until that point, revenues andexpenditures for optical services had never been able
to move into the black. Moreover, we needed to makeup for declining revenues from conventional telephone services by increasing revenues from Internet
protocol (IP) services, but that goal has not yet beenreached.
However, at NTT EAST, further expansion of optical facilities and aggressive provision of services by
NTT business companies have helped to move opticalservices into the black on a single-year basis, andincreases in IP service revenues have finally made up
for the decreases in telephone service revenues. Thisis a result of an increase in the average revenue peruser (ARPU), and I believe that we should undertake
more research and development (R&D) with an eye
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toward further increasing the ARPU.
In addition, there are many customers who are stillusing metallic circuits. It is therefore important that
we create an environment that enables these customers to make a smooth transition to optical services andthat we propose attractive ways of using these services. There are also groups of people such as theelderly who appear to have difficulty entering theworld of the Internet. I believe that we can contributeto improved revenues across the entire NTT Group by
providing optical services that can be used easily bysuch groups, thereby expanding the customer base.
—NTT has been energetically promoting Green ICT
for these last two years. This initiative, which includes
power consumption reductions as well as environmental conservation, would appear to be relevant
even at the time of a disaster such as the recent earthquake.
Yes, we have been working diligently to lower
overall power consumption to reduce CO2 emissions.
Now, however, after the earthquake, we also need toreduce the peak power consumption in addition to theoverall power consumption. At the same time, weneed to create new mechanisms that can prevent communications from being disrupted even if commercial
power supplies are no longer available.
To put this into perspective, let’s think back to theera of the analog telephone for a moment. The simple
act of picking up the receiver would immediately
connect a circuit, meaning that current would begin toflow and that the system would start using electricity.
By contrast, optical services are always connected, so
current is always flowing. With this being the case,studies have begun on control schemes in which theamount of power consumed is commensurate withthe amount of communications performed.
While the recent disruption of communications
can, of course, be attributed in part to immediate failures caused by the earthquake and subsequent tsunami, the biggest factor here was the eventual depletionof backup power supplies in radio base stations andNTT office buildings due to the relatively long cessation of commercial power. This is why I would also
like to improve current technologies for storingenergy as well as to develop and deploy new technologies of this kind so that we can provide customers with stable services over longer periods of time.
—We have heard that NTT’s laboratories played amajor role in recovery efforts after this earthquake.
Vol. 9 No. 10 Oct. 2011

NTT faces a variety of problems every day in theprocess of operating a network, and in order to comeup with solutions and reflect them in the field, its
business personnel and researchers interface witheach other to exchange ideas and opinions. In otherwords, the ability of business personnel and researchers to collaborate to determine R&D priorities reflects
the strength of a carrier that has its own researchlaboratories. In terms of making contributions tosociety, I think we should make the most of ourstrengths, whatever they may be.
Meeting diverse needs by accepting
outside technologies in order toenhance service development—The environment surrounding R&D has reallychanged since the earthquake. What issues do you
think will be important in the future?
Of particular importance is improving our service
development capabilities. For example, media processing technologies such as speech processing,image processing, and Japanese-language processing
are essential to providing new services. In this regard,
the NTT R&D Laboratory Group (NTT R&D) is fortunate in being highly competent in such technologies. But that is not to say that simply developing newtechnologies will enable us to create attractive andcommercially viable services. For new services to be
successful, convenience and market timing are also
important. That is, new services must also provide thecustomer with convenient functions and they must be
released to the market at just the right time. Up tonow, however, NTT R&D, in addition to developingView from the Top

key technologies for the creation of new services, hasalso been involved in the development of services
themselves and the making of proposals to NTT’s
business companies. As a result, researchers, who do
not necessarily specialize in such areas as customer
convenience and market timing, have taken it uponthemselves to do so. What researchers do best is technology development, and in this field, they tend to be
perfectionists, which can cause them to take moretime than perhaps necessary to release new technology.
Looking forward, I would like to promote thedevelopment of basic technologies, which is a strong
point of NTT R&D, while also rapidly bringing thosetechnologies to the attention of NTT business companies. In this way, we can receive feedback from themon aspects in which they specialize, such as how tomake functions even more convenient, and quickly
incorporate that feedback into the development process. In short, I would like to pursue unified development of new services together with the businesscompanies so that NTT can release highly competitive services to the market in a timely manner.
As services become increasingly diversified, technologies behind those services are likewise becoming
quite varied. Since we cannot develop all of thosetechnologies, we must closely consider what technologies we should tackle on our own from among
those needed to configure services. I believe that,

instead of adhering to just our own technologies, weshould be ready to accept technologies based on ideas
from the outside and the expertise of others. In otherwords, I think that we should face the challenge ofcreating new services with a spirit of open innovation.
This same kind of attitude is also needed in the
expansion of NTT’s global business. In addition to
proposing and providing our products overseas as wehave been doing up to now, it is becoming increasingly important that we pursue open innovation withNTT overseas consolidated subsidiaries and overseas
companies.
True achievement is not just creating new business:
It’s clarifying one’s role in R&D—It appears that the effects of the earthquake and theacceleration of globalization are forcing researchers
to change their way of thinking radically.
Looking back at the way I was trained, I can saythat my mindset has been to aim for perfection anddeliver results. I think that many researchers havenaturally adopted a similar attitude. However, theworld is changing quickly and the services that people desire are becoming increasingly diverse. For
these reasons, I am asking researchers to rethink what
it means to make a contribution to NTT’s business. In
particular, I am telling them that making a contribution does not simply mean introducing researchedand developed technology to the business companies
so as to turn a profit and reduce expenses. Making a
genuine contribution comes in a variety of forms. In
fact, I have defined six ways of making business contributions.
(1)	Short-term R&D to introduce R&D projects tobusiness companies, turn a profit, and reduce
expenses(2)	Development of a competitive R&D engine
while promoting open innovation(3)	Medium-term R&D with the aim of making
drastic improvements in business operations(4)	Cutting-edge R&D that can have a major impact
on society(5)	Support for business companies through optimal use of technology and contributions to business operations through advice based on accumulated knowledge(6)	Promotion and support of efficient R&D operations
It is also important that we assign targets to each ofthese research roles. I tell our researchers to think not
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View from the Top

I believe that by working to create new services by
setting high goals, demonstrating our strong points
without being ashamed of our weak points, andaccepting the expertise of others through open innovation, we can achieve great breakthroughs.

only about what can be done but also about whatshould be done while pursuing their work. This isbecause if we compare the accumulated results ofwhat can be done each year after ten years with theresults of setting targets that should be achieved inten years time, we will see a big difference in the levelof achievement and the results obtained, even for thesame area of research. Researchers need to set highgoals and devote their efforts toward achievingthem.
In this way, by clarifying the role that each andevery researcher needs to take on and by pursuing
R&D with high goals set for each role, I believe that
we as researchers can make more extensive andmeaningful business contributions.

Vol. 9 No. 10 Oct. 2011

Interviewee profile
Career highlights
Hiromichi Shinohara received the master’s
degree from the Graduate School of Waseda
University in 1978 and entered Nippon Telegraphand Telephone Public Corporation (now NTT) in
the same year. He became a project manager in
the NTT Access Network Systems Laboratories
in 1998. In 2003, he became an executive researchengineer and subsequently the general managerof the Access Network Service Systems
Laboratories of the Information Sharing
Laboratory Group. In 2007, he became the
Director of the Information Sharing Laboratory
Group. In 2009, he was elected Senior Vice
President and Director of the Research andDevelopment Planning Department of NTT.
Since June 2011, he has doubled as the Directorof the Information Sharing Laboratory Group.

Front-line Researchers

Take a Global View of Your Researchand Put Your Ideas to Work
Hiroshi Yamaguchi
Senior Distinguished Researcher
NTT Basic Research Laboratories
We asked Dr. Hiroshi Yamaguchi, Senior Distinguished
Researcher, to tell us about his research on nanomachine technology, which is attracting increasing attention in the world, fromhow he first conceived of pursuing nanomachines to the current
state of his progress. We also asked him how his ten years of
research in this field have influenced his outlook as a researcher,how he expresses his individuality as a researcher, and what
advice he would give to young researchers.

Globally acclaimed nanomachine technology—Dr. Yamaguchi, could you tell us about yourresearch in terms that a person with no knowledge ofsemiconductors can understand?
Sure. Let me give you a straightforward explanation using things we are all familiar with. To begin
with, what do you think of upon hearing the word
machine? No doubt many people think of a complicated piece of equipment made up of all kinds ofcomponents like gears and springs. This might be
Astro Boy, the famous android character, or a locomotive that moves with a huge grinding sound generated by its internal gears and springs. The preconception that a machine uses a large amount of energy isalso very common.
Nowadays, however, making things small is becoming a dominant way of thinking in various research
fields, and the same holds for machines. This field oftechnology is called micromachines or micro electromechanical systems. A projector for a personal computer, for example, can be equipped with an array of
mirrors each smaller than an insect’s foot. If such a
micromirror is irradiated with light, the direction of

reflection can be adjusted by fine mirror movement.
When this is applied across the entire array, it enables
the three primary colors (red, green, and blue, orRGB) to be synthesized on a screen and an image orvideo to be displayed. In short, micromachines areworking away continuously like clockwork inside theprojector, which represents one example of how
micromachine technology can be applied in practice.
Another example in common use can be found in car
automobile airbags. The deployment mechanism
includes a microscopic device less than 1 mm in sizethat vibrates at the time of a collision and a means for
detecting that vibration electrically.
Research and development on applying micromachine technology to such switch and sensor functions
is progressing. We are taking up the challenge ofdeveloping new techniques for making micromachines as small as possible. Our ultimate goal is toachieve micromachines on the nanotechnology level,
or in other words, nanomachines (Fig. 1).
—What kind of research activities are you coordinating to create such small machines?
Well, this is all fundamental research, so we are at
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Front-line Researchers

1 µm

1–2 µm long, 200 nm thick, and 300 nm wide;
each of these structures vibrates at a certain
frequency like a diving board.

Fig. 1. E lectron microscope image of typicalnanomechanical structures.

the stage of searching out what can be done andproposing what might be possible. There are twomain research flows here.
In the first one, our aim is to achieve a nanomachine
computer that extends the function of the switch to
information processing. Right now, we are just looking for the right way to go about this, but if we cancome up with a completely novel idea to make calculations by a nanotechnology-based machine, it justmight be possible to create a very-low-power computer. Such a nanomachine need not be limited tocomputers—it might also be possible to apply it tomemory devices and components used for processing
digital information. The key words here are low
power.
In the second research flow, we are pursuing therole of the micromachine as a sensor. We are researching ways of improving the sensitivity of existing
accelerometers by several orders of magnitude, andour ultimate goal is to be able to detect contact witheven one atom! Our theme here is “How small a force
or object can we detect?” In this role, there is muchanticipation from many fields for applying micromachines to biotechnology, DNA (deoxyribonucleicacid) detection, and medical laboratory equipment, as
well as to the pursuit of limits in physics and thesearch for minimum units in physical movement andforces.

Vol. 9 No. 10 Oct. 2011

—So your research is exploring unknown worlds.
How far will these research efforts progress?
There are various viewpoints on how far our
research can go, so I can’t really say in just a few
words, but I can tell you about some results that werecently announced as examples of the progress
we’ve been making.
In April 2008, we proposed a nanomachine computer using a new principle for performing digital
operations by using the minute vibration of a beamspring (Fig. 2). The heart of this device is the beamspring, which is thinner than the diameter of a humanhair. In this device, a period offset occurs when the
beam spring vibrates with an extremely small amplitude equivalent to only a few tens of atomic diameters(about 10 nm). By making such offsets correspond to‘0’ and ‘1’ bits of information, we successfully performed 1-bit basic operations using a nanomachine.
Achieving computation in this way using theextremely small vibrations of a beam spring suggests
the possibility of a very-low-power device.
Moreover, in September of the same year, as joint
research with Delft University of Technology in the
Netherlands, we fabricated part of a superconducting
quantum interference device (SQUID) as a nanomachine structure (beam spring) and successfully
detected minute vibrations on the order of one tenthousandth the size of an atom, which is about ten
femtometers (10 fm) (Fig. 3). Observing quantum
phenomena in a macroscopic object is a difficult challenge, but this new technique might make it possible
in future. Although it has frequently been confirmed
experimentally that the behavior of atoms—the constituent elements of all matter—is governed by quantum mechanics, which describes the basic laws of the
microworld, experimentally investigating how macroscopic objects in the real world behave in quantum
terms is expected to become a major research themein the years to come. In short, we fabricated a vibration sensor with extremely high sensitivity for use inresearch of this type and successfully detected vibration on the order of one ten-thousandth the size of anatom.
More recently, we announced platform technologythat shows promise for increasing the degree of integration in nanomachine computers. This technology
is the first in the world to offer the possibility of configuring a logic circuit with only one basic device
through the development of a digital operation
technique that can execute multiple logic operations
simultaneously. Up to now, multiple transistors have

Front-line Researchers

Input signal(from previous bit)Electrode B
Electrode C

Electrode B
Electrode A
Beam-spring section

Vibration direction

Electrode A

Excitation
periodic signal

Electrode C
Schematic diagram
Output signal(to next bit)

100 µmTop-view micrograph of device

Fig. 2. Micrograph and schematic diagram of nanomachine device.

Current

When bent upwards

When bent downwards

Current

Direction ofmagnetic fieldArea
increases.

Area
decreases.

Vibration
Microjunction
Beam-spring
sectionCurrent

Superconducting
circuit

Length of beam-spring section: 50 µm

Beam spring
vibrates.

Circuit areachanges.

Current
Vibration of spring changes the circuit area.

Magnetic fluxchanges.

Resistancechanges.

Fig. 3. Principle of ultrasensitive vibration sensor.

been necessary for even the most basic of logic
operations, but with this new technique, we have successfully executed multiple logic operations with justone device.
These technologies are not ready to be used in thedevelopment of actual equipment, but we will be testing the feasibility of applying them to practicaldevices in future research.

—When did you begin this research?
I began this research on nanomachines in 2000.
Actually, I had been studying fundamental semiconductor properties up until 1998, but in this year I wastransferred to the Planning Department of NTT Laboratories for a two-year stint. As a result, my work
shifted from research to management. Upon completing this assignment, I found that I would be far behind
other researchers if I were to continue with the same
NTT Technical Review

Front-line Researchersline of research after a two-year hiatus, so I thought,“Why not try something new, something that no one
has worked on yet?”
As a researcher, this two-year period of management duties prevented me from performing any
experiments, but that did not mean that I took a breakfrom research activities. Looking back, it was a great
opportunity for making a big change in the way I
looked at research. I learned of new research trends
and was able to exercise originality and express myown ideas without imitating anyone.
During my student days, I enjoyed the work of
Shinichiro Tomonaga, the renowned theoreticalphysicist, and I read many books by him and about
him and his work. Many wise quotes have been attributed to him, and among these, I cannot forget thisone: “If there is a principle that I ascribe to, it’s to not
do what other people do.” Being a follower may be
comfortable, but doing things differently from othershas shaped my stance on research in no small way.
I also felt that, as one gains experience, the overall
direction of the research that you are engaged incomes into view. I thought that by obtaining a firm
understanding of the principle roles of your research—by taking a global overview instead of focusing on
the fine details—and then applying your own originalideas, you could give birth to incredibly novel technology.
There were just two or three groups around theworld that had begun research on nanomachines atthat time, and I kept a close eye on their progress. And
it occurred to me that combining the semiconductor
technology that I had researched for many years withnanomachine technology could very well help me
create some very interesting devices. Now, after ten
years of researching nanomachines, I feel that things
are finally taking shape.
A ten-year journey of experiencing growing
pains but delivering world-first technologies—Was it smooth going during these last ten years?
It was very hard at the beginning! I think that myresearch style is based more on the new ideas thatcome into my mind than on continuous and steadyeffort. I like new things, and I’m not satisfied unless I
can move quickly on a new idea. But upon moving to
the Planning Department in 1998, it suddenly dawned
on me that the work of management would keep mebusy and that I would not be able to research my ideas
any day soon. So, while keeping abreast of nanomaVol. 9 No. 10 Oct. 2011chine trends, I used to do some thinking on my days
off or before going to bed. In this way, I gradually
accumulated ideas. Then, when I returned to researchin 2000, I found that those two or three groups elsewhere in the world researching nanomachines had
already been announcing amazing results one after
another. Of course, I had just started, and because ofthis late start, I wanted to do something different
instead of just following the pack. But it’s not that
simple to get immediate results from something new
and different. I was trying to produce results in anenvironment in which the people around me really
couldn’t help me, so perhaps it’s natural that the earlydays of my research here were difficult. In fact, I
began this research on my own, and I could notachieve even vibration measurement, which otherresearchers were doing on a routine basis. Being able
to detect vibration would be the first step toward creating a device like a sensor, but I still could not doanything that would constitute this first step. So I got
a real taste of growing pains here.
—How can vibrations be detected?
The resistance of a vibrating semiconductor changes as a result of bending, and the task is to read thatchange from the outside. However, this change inresistance appears as an extremely small change incurrent on the order of one millionth of the appliedcurrent. In retrospect, reading such a small change incurrent is not so difficult, but at the time, the knowhow to do so was simply non-existent, so I had nochoice but to fabricate structures and devise
characterization methods on my own from scratch.
It was around this time that an intern from France
was assigned to me to work as my assistant. One ofhis duties was to carry out experiments under mysupervision. When an experiment was going well, mytask of supervising him went well too, but when no
progress was being made, he would have no material
to report on, so I found myself worrying not only
about myself but also about my assistant. This was adifficult environment to be in.
To be honest, this period at the beginning of theseten years of research was the most trying. But then,on Christmas night in 2000, we were working late,
and we detected minute vibrations for the very firsttime, which means that we had successfully completed the first stage of our research. What a wonderful Christmas present that was! And I remember well
how happy this made my French assistant.
Somehow, our research continued to progress. InFront-line Researchers

2004, a paper that my colleagues and I wrote was
accepted by the prestigious journal Physical Review
Letters of the American Physical Society and it
received enthusiastic praise from readers. Then, in
2007, my colleagues and I developed an original
device called a parametric resonator. I was honored
that this technology received much praise from outside NTT, and it made me feel that our research was
finally taking off.
—In such a difficult environment, you might havegiven up. How were you able to persevere?
Perhaps it was because I had already left one
research area before. When starting a completely newline of research, it feels as if the ladder has beenpulled away from underneath you leaving you stranded. I think that making up my mind to go forward at
any cost had a big impact on how I dealt with thissituation. Furthermore, while my experiments did not
go as planned in the beginning, doing them over andover again eventually produced not only results that I
had hoped to find but also very interesting ones that I
had not expected at all. A feeling of “I can do this!”suddenly came upon me.
It is essential to continue with research even if
results are not immediately forthcoming. And when I
say continue, I also mean exploring new possibilities.
In other words, I think that a researcher should strive
for a good balance between a stubborn attitude that
continues with one approach and an adventurous attitude of not being afraid to try new things.
Experiencing the true pleasure of monozukuri—Other than research, do you have other intereststhat take up your time?
Yes, I do. Since childhood, I have enjoyed making
things, which in Japanese we call monozukuri. I
began assembling radios as a kid, and since then, I’ve
assembled or made a variety of things, like stereo
amplifiers, speakers, racks, desks, and small balcony
ponds. My current work leaves me with little time forthis pursuit, but I have recently built some bookshelves for my daughter’s desk and a stand for mylarge-screen television (Photo 1). The true pleasureof making things yourself comes from possessing aunique item that exists nowhere else in the world andcreating something that completely matches yourpersonal needs. I love the feeling of looking for thebest way to make something and finally completing

Photo 1. H
 omemade items: amplifier, rack, television stand,corkboard, speakers, etc.

it, which tells me something about the research process. For example, techniques for producing goodsound from speakers and methods for amplifying
small electrical signals in a stereo amplifier with low
noise are very similar in concept to what I use in generating vibration in the nanomechanical devices that
I’m currently working on and amplifying those signals. In this sense, the ability to work at something
related to things that I first learned about throughchildhood hobbies gives me great satisfaction.
In addition, since I’m not so young anymore, I’m
concerned about maintaining my health, and though
I’m not a sports enthusiast, I jog several kilometers on
the weekends and sometimes walk to work from thetrain station, instead of catching the bus, which takes
me about fifty minutes. This exercise helps improvemy blood circulation and make me feel better all
around.
—Dr. Yamaguchi, would you leave us with somewords of encouragement for young researchers?
I would love to. First, it’s vitally important for a
researcher to express his or her originality, and this,of course, applies to me too. I think that young
researchers, especially talented and ambitious ones,
want to experience great results early on and to perform work that they have devised themselves. But I
would ask them to develop their originality inresearch carefully without rushing things along.
Instead of going all out for an early home run, I
believe that focusing diligently on the work that has
been assigned to you and then expressing your originality as an extension of that work will be more effective in putting you on the path to success. At first, thisNTT Technical Review

Front-line Researchers

might take some time, but in years to come, there will
be more than enough opportunities for you to demonstrate the knowledge and know-how that you haveaccumulated. I think that many young researchers are
ill at ease with the work that has been assigned tothem since it differs from the main field of their university studies and is not what they feel they are goodat. I can empathize with this, as I was very impatientwhen I entered NTT Laboratories. But in truth, I thinkthat a good approach is to figure out how to make thebest of work that has been assigned to you regardlessof your past studies and to supplement that work withyour original ideas and methods. You may experiencegreat difficulties in the beginning, but once your hard
work begins to bear fruit, you should be able to lookback at the road you have taken with a whole newperspective. So, to all young researchers, I wish you
great success in your endeavors.

Hiroshi Yamaguchi
Senior Distinguished Researcher, Executive
Manager of the Physical Science Laboratory andGroup Leader of the Nanostructure Technology
Research Group, NTT Basic Research Labora­
tories.
He received the B.E. and M.S. degrees in physics and the Ph.D. degree in engineering from
Osaka University in 1984, 1986, and 1993, respec­tively. He joined NTT Basic Research Laboratories in 1986. His current interests are micro/
nanomechanical devices using semiconductor
heterostructures. He has been a guest professor at
Tohoku University since 2006. He is an IOP
Fellow and a member of the Japan Society ofApplied Physics, the Physical Society of Japan,
and IEEE.

Vol. 9 No. 10 Oct. 2011

Feature Articles: Collaborations with Universities
Leading to Open Innovation in NTT’s R&D

Efforts Toward Organizational
University Collaborations
Terufumi Shinomiya†, Takashi Ikegawa, Katsumi Iwatsuki,
Akihiko Hashimoto, Yasuyoshi Okada, and Eriko Sano
Abstract

NTT Service Integration Laboratories is striving to create organizational collaborations with universities across a wide range of academic disciplines in order to carry out joint research projects and humanresources exchanges more efficiently and effectively. In this article, we introduce the framework foruniversity collaboration and the content of activities. We also introduce specific examples of such collaborations.

1. Introduction
Societies today cannot help but be drawn into amaelstrom of rapid globalization, drastic changes inthe business landscape, and fierce competition on a
global scale. To respond to the rapid changes in social
needs and diversification, it is necessary to partnerorganizations capable of thinking in different ways
and perform research and development (R&D) thatincorporates such thinking. In Japan, academicindustrial collaboration—linking companies anduniversities—in R&D and exchanges of humanresources took a great leap forward as a result of theestablishment of national university corporations in
2004, which drew the government’s attention [1].
NTT is also working to create organizational R&D
collaborations with universities [2].
To research and develop basic technologies in orderto create new forms of communication and their supporting networks and to actively engage in advanced
basic research with a ten-year outlook, NTT is
engaged in R&D collaborations with universities
across a wide range of disciplines. We have great
expectations for diverse results by achieving open
innovations. The fruits of these innovations will be
profitable not only from a technological standpoint
but also from a social standpoint and will make pos† NTT Service Integration Laboratories
Musashino-shi, 180-8585 Japansible R&D that integrates disparate fields. For universities, such collaborations present a win-win situation
for improving research and educational activities.
In this article, we introduce our framework for university collaboration and the content of our activities.
We also introduce specific examples of such collaborations.
2. Levels of collaboration
NTT has a long history of collaborating closelywith universities to conduct joint research. However,such collaborations have been based on individual-toindividual relationships among fellow researchers.
Thus, it has been hard to grasp the overall state oforganization-to-organization activities. Moreover,because the points of contact were unclear, problems
emerged, including a lack of continuity in the collaborations, difficulties with collaborations acrossmultiple fields, and researchers having to shoulder
the burden of contract negotiations related to joint
research.
To solve such problems, we began efforts towardcollaborations with universities on the organizational
level, and these have resulted in various joint research
projects and human resources exchange. Our efforts
center on signing comprehensive organization-toorganization contracts and creating collaborationcommittees consisting of executives from both NTT
and universities to serve as the core of the
NTT Technical Review

Feature Articles

Tohoku University (July 2008)- Physical properties/materials- Integration of communication anddisparate fields

Hokkaido University (Dec. 2008)- Single-electron devices & electron spin control- Life-log processing/appliances

Tokyo Institute of Technology(Sept. 2008)- Optical device technologies &environmental energy technologies

The University of Tokyo (June 2007)
Sharing knowledge for IT safety and security

Kyoto University (June 2006)
Advanced communication environment

Waseda University (Jan. 2008)- Basic and device-related technologies- ICT platforms for Information

Kyushu University (July 2004)
Research on integration of liberal artsand science

Osaka University (June 2005)
Information communication

Keio University (Mar. 2006)
Broadband communication,ubiquitousness, IP networks

Nagoya University(Mar. 2006)
Integration of networks andapplications

Collaboration between university and NTT
Collaboration between university and NTT & NTT EAST
Collaboration between university and NTT & NTT WEST

Research Organization of Information and
Systems (Oct. 2009)(National Institute of Informatics, Institute of
Statistical Mathematics)- Architectures- Contents
ICT: information and communications technology
IP: Internet protocol
IT: information technology

Fig. 1. Universities and research institutes in organizational collaborations with NTT. Fields of joint research are listed under
the partner’s name. Dates in parentheses are contract-signing dates.

collaborations. In July 2004, we signed the first organizational collaboration with Kyushu University.
Since then, NTT has signed agreements with ten universities and one research institute, as shown in Fig.
1. Moreover, NTT EAST and NTT WEST, which are
intimately connected with regions outside Tokyo,
have forged close relationships with three institutions.
The planning and operation of an organizational
collaboration is the responsibility of the collaborationcommittee, which is composed of collaboration managers and research representatives from both parties.
The committee has a shared awareness of the R&D
being tackled and the human resources available forexchange and creates collaborative relationships thatspan a wide range of disciplines.
To strengthen and further expand joint research
projects that have past connections, we are working
on creating new collaborations between departmentsthat have not collaborated before; we are also creating
integrative collaborations that span multiple laboratories. We are doing this through matching conducted
Vol. 9 No. 10 Oct. 2011

from a wide perspective on the basis of the needs andseeds of each party. In the area of human resources ex­­change, we are working on accepting student interns
and establishing new occasions for technologicalexchanges through the participation of a wide range
of departments, while being aware of sustained development.
The issues associated with conventional collaborations, their drawbacks, and the goals and methods oforganizational collaborations are shown in Fig. 2.
The forms of collaboration and the contact department on the university side may differ depending on
the university. However, for NTT R&D, the unified
point of contact for all organizational collaborations
is NTT Service Integration Laboratories.
3. Achievements
By utilizing the special features of each university
and complementing each other’s strengths, we haveconducted joint research and human resources
exchanges in various areas centered on the field ofFeature Articles

Conventional
collaborations
with universities

IssuesDrawbacks

Researcher-to-researcher collaboration

Research content confined to narrow field

Negotiation of joint research contracts

Concluding a contract takes a lot of time

Publishing research results

Only small-scale business can be created

Goal
Organizational
collaborations
with universities

MethodIntroduction of plan-do-check-act(PDCA) cycle
Improve quality
Rapid and timely collaborations tocreate businessNTT

Determine directions with collaboration committee
Establish goals and evaluation of joint research results
Comprehensive agreement on intellectual property
Collaboration committee

University

Lab A
Lab B

Department A
University-industry
collaboration
section

Department B…

…

NTT Service
Integration
Laboratories-Establish collaboration
activity plan
-Match research themes-Promote collaboration

Intellectual
property section

NTT Intellectual
Property Center

Fig. 2. Advancing organizational collaborations with universities.

communications, including physical properties andmaterials science, leading-edge devices, IP (Internet
protocol) networks and ubiquitousness, informationand communications technology (ICT) (including
information security), as well as higher-level themes
such as audio/video and communications. We are also
working on social concerns, including energy and theenvironment, disaster prevention, medical science,
and agricultural science.
In FY 2010, more than 150 joint research projects
were carried out through organizational university
collaborations, resulting in more than 100 patentapplications being filed and more than 200 papers
being submitted to academic journals and presented
at international conferences [3].
We are also committing ourselves to transmitting
the achievements of our joint research projects to the
public through press releases from NTT and our university partners (see Table 1) and by publishingbooks. As an example of the latter, we published theresults [4], [5] of our research collaboration with
Kyoto University’s Disaster Prevention ResearchInstitute in a book aimed at the general public [6].
Studies in disaster prevention have until now focusedon protecting society against natural disasters, forexample through anti-disaster technologies such as
construction methods to improve the ability to resistdisasters. However, this book is premised upon theoccurrence of disasters and focuses on effective
implementation of relief and recovery and on technologies for minimizing the harmful effects of natural
disasters. It calls for the creation of a resilient society
by exploiting ICT. Such a society would have resistance to natural disasters and greater recovery
strength.
Next, we introduce two examples of humanresources exchanges.
3.1 Kyushu University COE ProgramFirst, we were involved in two programs: (1)MEXT’s 21st Century COE Program “Developmentof Dynamic Mathematics with High Functionality”(MEXT: Ministry of Education, Culture, Sports, Science and Technology in Japan; COE: Center of
Excellence) conducted by Kyushu University’s Faculty of Mathematics (2003–2007) and the graduate
school reform support program “Training Programfor Ph.D. and New Master’s in Mathematics for
Industry” (2007–2009) and (2) the Global COE Program “Education-and-Research Hub for Mathematics-for-Industry” (2009–2013) [7]. The curricula ofthese programs require an internship of three or moremonths by doctoral students. Since 2006, NTT has
been accepting students every year as interns for such
NTT Technical Review

Feature Articles

Table 1. Press releases of joint research achievements.
Year

Date

Source(s)FY2010 Mar. 15, 2011 Hokkaido University

Theme
Elucidation of physical constants in the control of electron spin:
Accelerating R&D of next-generation electronic devices

Nov. 2, 2010

NTT and Kyoto University Development of error resilience technology that brings quantum computing a big
step closer to reality:
Enabling quantum computing by using electron gates with large errors

Sept. 3, 2010

Kyushu University,
Takarazuka, Kadokawa,and NTT WEST

Joint R&D for highly realistic sensations during live transmission with
communication networks:
Live transmission of Takarazuka Review with highly realistic sensations

Sept. 2010

The University of Tokyo,
Toyo University,
NTT

Verification of divergence and security using “The International Comparative
Survey on Concerns when Using the Internet”:
Clarifying characteristics of anxiety felt by Japanese users even when safe

July 27, 2010

Nagoya University

Test release of MAGIC, an automatic English fill-in-the-blank test generation system:
Promise of creative learning support

June 29, 2010 Tokyo Institute ofTechnology

Direct generation of frequencies over 1 THz at room temperature:
Developing the world’s first electron device

FY2009 July 27, 2009

NTT and Tokyo Instituteof Technology

Success in developing multifunctional 2-qubit (quantum bit) logic element:
Realizing inversion of control logic and exchange operation with one electron

July 17, 2009

Tohoku University, NTT
EAST, and NTT

Testing for collaborative business of “Invented by Miyagi”’s new image resolution:
Implementing a renewal opening ceremony for “HIKARI PARK”

FY2008

April 30, 2009 NTT and Kyushu
University

Successful observation of temporal change in the shape of a receptor:
Elucidating the structural change mechanism of ATP receptor

Dec. 25, 2008 Keio University andNTT

Success in demonstrating multi-location teleconference with 4K ultrahigh-definition
resolution: Creating a network cooperative industry using ultrahigh-definition video

May 26, 2008

Test of the world’s first teleportation-based quantum calculation:
A breakthrough in making photon quantum computers

NTT and Osaka
University

programs. We have also been continuing to accept
summer interns for the new master student development program and dispatching lecturers. Through its
COE program activities, Kyushu University has
established an internationally unprecedented Instituteof Mathematics for Industry. This laboratory isJapan’s third mathematics research institute, following the Research Institute for Mathematical Sciences(Kyoto University) and the Institute of Statistical
Mathematics [8].
3.2 Keio University Symposium
In February 2011, the collaboration committee of
Keio University and NTT held the symposium “Seeking to Realize Ubiquitous Innovations through ICT:From Creating Leading-edge Basic Technologies toApplication” at Keio University’s Mita campus [9].
Atsuhiro Goto, the director of NTT Cyber Communications Laboratory Group (now at Institute of Information Security) gave the keynote address entitled“The Promise of Academic-Industrial Collaborations: Creating New Services for the Optical Era”
(see Photo 1). Next, researchers from Keio University and NTT gave six presentations in three areas––Vol. 9 No. 10 Oct. 2011

electronics and physical properties/materials science,
networking, and human communication technologies, announcing the results of their cutting-edge
research. There were over 170 participants from companies, research institutes, and government agencies
as well as universities. A rich variety of presentations
on a wide range of topics was given, from basic
research to applications in the field of ICT, making
the symposium an overwhelming success.
4. Collaborations with overseas universities
NTT is also exploring organizational collaborations
with overseas universities. Recognizing that collaborations in Asia are growing in strength, we are proceeding with collaborations with universities in
China, Vietnam, and India. Because there are issues
such as differences in customs and laws, we are stillat the stage of carrying out trials of offshore softwaredevelopment related to research rather than conducting R&D collaborations like those with domestic
universities. The universities have favorably evaluated the acquisition of new research themes and thetraining of students. For NTT, the advantages areFeature Articles

promoting exchanges of human resources and reducing costs.
5. Conclusion
For efforts toward organizational university collaborations, it is critical to regularly commit energy to
the creation of new research themes as part of themetabolism of an organization and to develop strong
research themes that take account of business andsocial developments. It is also essential to widely andcontinually foster mutual understanding throughexchanges of human resources. With NTT’s organizational university collaborations, we are not only
creating win-win relationships with universities, butalso working to improve Japan’s growth strategy andincrease its international competitiveness and contribute to solutions to society’s problems.
References
[1]
[2]
[3]
[4]

http://www.mext.go.jp/english/science_technology/1303792.htm
http://sangakukan.jp/journal/journal_contents/2008/04/articles/080401/0804-01_article.html (in Japanese).
http://www.ntt.co.jp/RD/OFIS/active/2010pdfe/rd/data.html
K. Iwatsuki and H. Hayashi, “Realization of Resilient Society with
Information Technology Revolution,” J. Disaster Research, Vol. 5, No.
6, pp. 622–626, 2010.

Terufumi Shinomiya

Senior Research Engineer, Supervisor, Industry Academic Collaboration Group, Service
Deployment Strategy Project for Business Promotion, NTT Service Integration Laboratories.
He received the B.S. and M.S. degrees in mathematics from Kyushu University, Fukuoka, in1985 and 1987, respectively. He joined NTT
Laboratories in 1987 and studied network performance of B-ISDN and IP-based networks. He
also engaged in studies on communication quality for voice over IP. During 1997–2004, he wasa Rapporteur of ITU-T SG13. Since 2007, he has
been promoting strategic R&D collaboration
between industry and universities. He received
the ITU-T Certificate of Appreciation in recognition of his contribution to standardization activities and his excellent work performed in 2004.
He is a senior member of the Institute of Electronics, Information and Communication Engineers (IEICE).



Photo 1. Keynote address.

[5]
[6]
[7]
[8]
[9]

Y. Maeda, M. Higashida, K. Iwatsuki, T. Handa, Y. Kihara, and H.
Hayashi, “Next Generation ICT Services Underlying the Resilience
Society,” J. Disaster Research, Vol. 5, No. 6, pp. 627–635, 2010.
Kyoto University–NTT Resilience Joint Research Group, “Creationof the Resilience Society,” Nikkei BP Kikaku, 2009 (in Japanese).
http://gcoe-mi.jp/english/program
http://www.imi.kyushu-u.ac.jp/eng/pages/about.html
http://www.rcp.keio.ac.jp/event/2010/20110225_01.html (in Japanese).

Takashi Ikegawa

Senior Research Engineer, Industry Academic
Collaboration Group, Service Deployment Strategy Project for Business Promotion, NTT Service Integration Laboratories.
He received the B.E. and M.E. degrees in finemeasurements and system engineering from
Nagoya Institute of Technology, Aichi, and the
Ph.D. degree in mathematical and computing
sciences from Tokyo Institute of Technology in
1985, 1987, and 2008, respectively. He joined
NTT in 1987 and has been involved in network
protocol standardization with the International
Organization for Standardization and in studies
on network architecture with the Telecommunications Information Networking Architecture
Consortium (TINA-C). He has been a visiting
Professor at Kyushu University and is currently apart-time lecturer at Keio University. His researchinterests include performance modeling andanalysis of communication protocols. He is asenior member of IEICE and a member of the
Operations Research Society of Japan.

NTT Technical Review

Feature Articles

Katsumi Iwatsuki

Senior Research Engineer, Supervisor, Industry Academic Collaboration Group, Service
Deployment Strategy Project for Business Promotion, NTT Service Integration Laboratories.
He received the B.E. degree in electronics
engineering from Nagoya Institute of Technology, Aichi, and the M.E. and Ph.D. degrees inelectronics engineering from the University ofTokyo in 1981, 1983, and 1986, respectively. In
1986, he joined NTT Yokosuka Laboratories,
where he engaged in research on high-speed
ultralong-distance optical soliton transmission,
ultrahigh-speed nonlinear pulse transmission
with optical TDM techniques, optical fiber sensors, and ultrafast electrical signal measurement.
In 1996, he was transferred to NTT headquarters
to promote strategic technology planning. Since
1999, he has been engaged in research on broadband metropolitan/access networks based on
WDM technologies and millimeter-wave generation with micro/millimeter-wave photonics technologies, where he headed the Photonic Communications System Research Group in NTT
Network Innovation Laboratories and WDM
Access Group in NTT Access Network Service
Systems Laboratories. In 2007, he moved to NTT
Service Integration Laboratories, where he has
been promoting strategic R&D collaboration
between industry and universities. He has been
engaged in coordinating many research collaborations and promoting some of them such as
terahertz communication systems and sensors,
broadband ubiquitous networks based on wired
and wireless convergence/integration, and nextgeneration ICT services underlying the resilient
society. He is the author or co-author of morethan 150 papers and letters in technical journals
and international conferences. He is active in the
IEICE’s Technical Committee on Microwave andMillimeter-wave Photonics. Some of his recent
activities include Committee member of AsiaPacific Microwave Photonics Conference 2012,
TPC member of the 30th and 31st Progress In
Electromagnetics Research Symposium (PIERS),
and session organizer of “Microwave/Terahertz
Photonics Technologies and their Applications”
in PIERS (2007–2011). He received the Young
Engineer’s Award from IEICE in 1991, the
APCC/IEEE ComSoc APB Joint Award in 2001,
and the European Microwave Conference Prizein 2006. He is a member of IEICE.

Akihiko Hashimoto

Senior Research Engineer, Industry Academic
Collaboration Group, Service Deployment Strategy Project for Business Promotion, NTT Service Integration Laboratories.
He received the B.S. and M.S. degrees in communication engineering from Tokyo Institute ofTechnology in 1983 and 1985, respectively.
Since joining NTT Electrical Communication
Laboratories in 1985, he has been studying computer graphics and three-dimensional remoteimage input. He is currently working on anindustry academic collaboration. He is a memberof the Institute of Image Information and Television Engineers of Japan.

Vol. 9 No. 10 Oct. 2011

Yasuyoshi Okada

Senior Research Engineer, Industry Academic
Collaboration Group, Service Deployment Strategy Project for Business Promotion, NTT Service Integration Laboratories.
He received the B.S. and M.S. degrees in mathematics of science from Tohoku University,
Miyagi, in 1983 and 1985, respectively. He
joined NTT Basic Research Laboratory in 1985.
From 1985 to 1992, he studied artificial intelligence and a basic theory of computer science andalso made a new theory “Graph Rewriting Systems” which lets one apply network reliability
analysis. From 1993 to 1997, he was with NTT
Telecommunication Networks Laboratories
engaged in the development of a traditional network reliability design method and an initial
Internet quality design method. From 1998 to2000, he was engaged in the development of the
OSPF protocol and the BGP protocol for a newcommercial network. From 2001 to 2002, heplanned and executed a joint experiment of the
J-League Omiya Ardija and NTT Service Integration Laboratories aimed at developing applications in the optical fiber communication network. From 2003 to 2007, he worked in a service
project to commercialize a product developed in
the laboratory. He has been engaged in industryacademic collaboration since 2008. He is amember of IEICE, the Information Processing
Society of Japan, Information Systems Society ofJapan, and Japanese Society of Science and Football.

Eriko T. Sano

Senior Research Engineer, Service Deployment Strategy Project for Business Promotion,
NTT Service Integration Laboratories.
She received the B.E. and M.E. degrees fromthe Department of Physics, Ochanomizu University, Tokyo, and the Ph.D. degree from the Faculty of Science and Engineering, Waseda University, Tokyo, in 1986, 1988, and 1999, respectively. She joined NTT Basic Research Laboratories in 1988 and studied the growth mechanismof III-V and III-VI semiconductors. From 1997
to 2001, she was with NTT AT as a Senior Manager in the Corporate Strategy Planning Headquarters. She qualified as SAP R/3 Certified
Application Consultant “Controlling” in 1999.
She has twelve years of experience in businessdevelopment at NTT Research and Development
Planning Department and NTT Service Integration Laboratories. She is a member of the Physical Society of Japan and the Japan Society ofApplied Physics.

Feature Articles: Collaborations with Universities
Leading to Open Innovation in NTT’s R&D

Room-temperature
Resonant-tunneling-diodeTerahertz Oscillator Based on
Precisely Controlled Semiconductor
Epitaxial Growth Technology
Hiroki Sugiyama†, Safumi Suzuki, and Masahiro Asada
Abstract

This article presents the recent achievement of fundamental oscillations in resonant tunneling diodes(RTDs) above 1 THz at room temperature. One of the key technologies for this achievement is precisely
controlled epitaxial growth of ultrathin semiconductor heterostructures. The structural design of oscillators and microfabrication technology are also crucial. To increase the oscillation frequency toward theterahertz range, we devised a novel RTD structure with a graded emitter, which effectively reduces boththe operating bias voltage and electron transit time in the collector depletion region. An InP-based
InGaAs/AlAs RTD oscillator with a graded emitter and 1.2-nm-thick barriers exhibited fundamental
oscillations with frequencies of up to 1.04 THz at room temperature, which is the highest oscillation
frequency ever reported in single solid-state electron devices. This project is part of collaborative
research and development between NTT and Tokyo Institute of Technology.

1. Introduction
The resonant tunneling diode (RTD) is a quantumeffect semiconductor device using quantum mechanical tunneling. Its operating principle is based on theresonant tunneling effect proposed by Tsu and Esaki
in 1973 [1]. The conduction-band profiles of a conventional RTD and their relation to current-voltage
characteristics are schematically shown in Fig. 1. The
case under zero bias is shown in Fig. 1(a). The RTD’s
active layers consist of a double barrier (DB) structure where an undoped quantum well layer is sandwiched between two undoped barrier layers. Owing
to the use of the quantum mechanical behavior of carriers, each layer of the DB structure is usually on theorder of 1 nm thick. The DB layers are connected† NTT Photonics Laboratories
Atsugi-shi, 243-0198 Japan

with heavily doped emitter and collector contact
regions filled with electrons. Discrete quasi-bound orresonant levels are formed in the well layer. In Fig. 1(a),the lowest resonant level is indicated. As the bias voltage increases, electrons flow from the emitter to thecollector through the resonant level. The current
increases almost linearly until the emitter’s conduction band edge exceeds the resonant level, as shownin Fig. 1(b). A further increase in the bias voltage
causes a sharp drop in the current because the resonant level falls below the emitter’s conduction bandedge, as shown in Fig. 1(c). The current-voltage characteristics in Fig. 1(d) exhibit negative differential
conductance (NDC), which is one of the distinctive
features of RTDs. The ratio of peak current to valley
current (IP/IV) in Fig. 1(d) is called the peak-to-valley
ratio (PVR) and is one of the figures of merit of
RTDs.
One practical application of such NDC devices is a
NTT Technical Review

Feature Articles

Barriers
EmitterCollector

Well

Resonant
level

Electron

V

(a)

(b)

IP
Current (A)

(b)

(c)

IV
V

(a)
VV
VP
Voltage (V)

(c)

(d)

Fig. 1. C onduction band profiles of a DB RTD at three different bias voltages (V): (a) zero
bias (V=0), (b) resonance (V= VP), and (c) off-resonance (V= VV). (d) Schematiccurrent-voltage characteristics of a DB RTD.

Slot antennaStanding wave

Electric field

distribution

RTD

Slot antenna

C

L
GL

-Gd

RTD

(a)

(b)

Fig. 2. ( a) Fundamental structure of the RTD oscillator integrated with slot antenna.
(b) Equivalent circuit of (a).

high-frequency oscillator, which can be constructedby connecting NDC devices and external resonators.
The fundamental oscillator structure used in thiswork, which has an RTD integrated with a slot antenna [2], is shown in Fig. 2. The RTD’s NDC provides
the gain necessary for the oscillation. The slot forms
a standing wave of the electromagnetic field as aresonator and also acts as an antenna by radiating
output power at the same time. The equivalent circuit
Vol. 9 No. 10 Oct. 2011

for the structure in Fig. 2(a) is shown in Fig. 2(b).
Here, some of the parasitic elements such as contact
resistance have been omitted. Oscillation takes place
if Gd > GL, i.e., the NDC’s absolute value exceeds theslot antenna’s radiation loss. The oscillation frequency is determined by the parallel resonance of L and C
in Fig. 2(b) corresponding to the standing wave in
Fig. 2(a), where inductance L is dominantly producedby the antenna, and capacitance C is produced by theFeature Articles

Group-III atom
Group-V atom

Heterointerface

Source Gate

Drain

InP etching stopper
InAlAs barrier
InGaAs channel
InAlAs buffer
InP substrate

Step
(a)

(b)

(c)

Fig. 3. ( a) Schematic illustration of heterointerface of III-V semiconductors.
(b) HAADF STEM image of InP/InAlAs heterointerface in an InPbased HEMT. (c) Schematic layer structure of InP-based HEMT.

RTD and antenna.
The RTD’s high-speed operation is based on someof the RTD’s distinctive features. One is the short
resonant tunneling time, which corresponds to thequantum-mechanical tunneling time of an electron
passing through the DB structure; this is estimated to
be on the order of 1 ps or less. Another is the shortcharging time of its own capacitance. The RTD’s highcurrent density of over 1 × 105 A/cm2 and comparatively small capacitance effectively reduce the charging time. These are quite a contrast to other NDC
devices such as Esaki diodes where high current density is associated with high doping in the active
region, which significantly increases their capacitance and charging time. In the early stage of research,such excellent features of the RTD indicated that
RTD oscillators could operate at frequencies neverreached by other semiconductor devices. The first
demonstration of an RTD oscillator was reported by
Sollner in 1984 for GaAs/AlGaAs RTDs; the oscillation frequency was 18 GHz at 200 K [3]. The oscillation frequency reached 712 GHz at room temperaturein 1991 with InAs/AlSb RTDs [4].
Recently, the sub-terahertz (sub-THz) and terahertz(THz) ranges have been attracting a lot of interest
since there are various potential practical applications
such as broadband wireless communications, safety,
and security. Although the demands for room-temperature devices operating in the sub-THz to THz
range increased, no further increases in RTD oscillation frequency were reported until 2009. Room-temperature operation in the THz range has not yet beenachieved in any other single devices. NTT Photonics
Laboratories and Tokyo Institute of Technology(Tokyo Tech) have been collaborating on RTD THz
oscillator development since 2007. NTT has developed a precisely controlled epitaxial growth technique to obtain high-quality ultrathin semiconductor
heterostructures [5]. Tokyo Tech has developed
design and microfabrication technology for RTD
oscillators operating in the sub-THz to THz range [6].
In 2009, we reported a record-breaking fundamental
oscillation at 831 GHz [7]. Last year, we successfully
extended the fundamental oscillation frequency toabove 1 THz at room temperature [8].
In this article, we present essential technologies forthe achievement. Precisely controlled semiconductor
epitaxial growth technology developed in NTT and
its application to ultrahigh-speed electron devices aredescribed. The design and microfabrication technology for RTD oscillators developed by Tokyo Tech isalso presented. Finally, our approach to THz oscillation and its experimental demonstration are shown.
2. Precise control of semiconductor epitaxial
growth for ultrathin heterostructuresin ultrahigh-speed electron devices
The atomic configuration of an ideal III-V semiconductor heterointerface is schematically shown in
Fig. 3(a). The RTD’s DB structure consists of such
heterointerfaces between barrier and well. Good
crystal quality for such a heterostructure is essential
for modern semiconductor devices, such as high-speedtransistors, lasers, and photodiodes, to produce highperformance. For example, excellent abruptness of
NTT Technical Review

Feature Articles

InGaAs
AlAs barrier
1.2 nmInGaAs well

1.2 nmAlAs barrier
InGaAs(a)(b)

Fig. 4. ( a) Schematic of InGaAs/AlAs DB structure and (b) cross-sectional
TEM image of DB structure.

the layer composition is required in actual devices toform an ideal band profile. In Fig. 3(a), the atomic
composition changes abruptly at the interface, andthere is no mixing layer around the interface. Controlof the layer thickness on the order of 1 nm or less isalso required. In addition, heterointerface flatness isalso important for device performance since actual
heterointerfaces often include a high density ofmonolayer steps, which often affect carrier transport.
These III-V semiconductor heterostructures areusually fabricated by an epitaxial growth techniquesuch as molecular beam epitaxy (MBE) or metalorganic vapor-phase epitaxy (MOVPE), in which semiconductor epitaxial layers are grown by depositing
source materials on substrates. In NTT Photonics
Labs, MOVPE is mainly developed for advanced
semiconductor devices for broadband communication systems. In MOVPE, organic metals and hydrides
are used as precursors and supplied to the substrateduring epitaxial growth. For the fabrication of highquality heterostructures, control of precursor-supply
switching is one of the key procedures. NTT has
developed such key techniques and fabricated highquality heterostructures for practical devices. A highangle annular dark-field (HAADF) scanning transmission electron microscope (STEM) image of the
InP/InAlAs heterointerface in an InP-based highelectron mobility transistor (HEMT) developed in
NTT is shown in Fig. 3(b). The HEMT’s layer structure is shown in Fig. 3(c). In Fig. 3(b), each bright dot
corresponds to a group-III or group-V atom. It should
be noted that the brightness of dots corresponding togroup-V atoms changes abruptly at the interface,which means that the distribution of group-V atoms
Vol. 9 No. 10 Oct. 2011changes abruptly from arsenic to phosphorus. This
HAADF-STEM image demonstrates our excellent
control of compositional abruptness at the heterointerface. The abruptness provides high wet-etching
selectivity in the device fabrication process and contributes to excellent device characteristics. InP-based
HEMT integrated circuits based on our MOVPE
technology have been used in a 120-GHz advanced
broadband wireless communication system [9].
NTT has applied such epitaxial growth techniques
to the fabrication of high-performance RTDs. We
used InP-based InGaAs/AlAs DB structures because
the large conduction-band offset between InGaAs
and AlAs is beneficial to obtain a large PVR. Oscillation in the THz region requires peak current density(JP) of around 1 × 106 A/cm2 or more with a large
PVR. We have demonstrated precise control of a barrier thickness of around 1 nm and the formation ofhigh-quality heterointerfaces with excellent compositional abruptness and flatness [10]. An example of across-sectional TEM image of our RTD is shown in
Fig. 4. The image shows the uniformity of 1.2-nmthick barriers and the smoothness of the heterointerfaces. We have also confirmed excellent on-wafer
uniformity on a 3-inch wafer where the barrier-thickness fluctuation was estimated to be around ±0.1
monolayers.
3. Fundamental oscillation above 1 THz
at room temperature
Schematic drawings and microscope images of an
actual RTD oscillator integrated with a slot antenna
are shown in Fig. 5(a). The structures are based on
Tokyo Tech’s advanced semiconductor microfabricaFeature Articles

Bismuth resistor
Left electrode
RTD

Slot antenna

SiO2
DC BiasLeftelectrode
4 µm

InP substrate

Slot

RTD

1 µm

InP substrate RTD

Right electrode

Right electrode
(a)

(b)

Fig. 5. ( a) Schematic and microscope images of the RTD oscillator integrated with slot antenna.
(b) Cross-sectional SEM image of the RTD oscillator.

tion technology. The RTD’s electrodes are connectedto the antenna’s left and right electrodes. At bothedges of the antenna, the electrodes are overlappedwith a SiO2 layer between them. This structure forms
reflectors of high-frequency electromagnetic waves,and DC bias separation is achieved at the same time.
A resistor made of bismuth film is connected in parallel outside the antenna electrodes to suppress parasitic oscillation caused by the resonance formed byexternal circuits including the bias supplying lines. A
cross-sectional image of the RTD oscillator is shownin Fig. 5(b). The RTD’s emitter mesa area is around
1 µm2 or less. The emitter mesa area and slot antenna
length are key structural parameters that determine
the oscillation frequency and they were carefully
designed to increase the oscillation frequency.
We have improved the RTD’s layer structure toextend the oscillation frequency toward the THz
range. The structural-parameter dependences of RTD
characteristics, such as the effect of barrier thickness
reduction, have been investigated to obtain high JP
and reduce the resonant tunneling time. In addition,
our previous research revealed that lowering the operating bias voltage of the oscillator is important inorder to reduce the electron transit time in the collector depletion region because a low operating bias
voltage should suppress electronic transition from G
to the L valley, which leads to a decrease in electron
velocity [11].
To reduce the operating bias voltage, we have proposed a novel RTD structure with an undoped gradedGraded emitter
eBias voltage

Fig. 6. C onduction band profile of double barrier region in
the RTD oscillators with (red solid line) and without(dashed line) graded emitter at operation bias
voltage.

emitter. The conduction band profiles of the DB
regions in RTD oscillators with and without a graded
emitter at around the operating bias voltage are shownin Fig. 6. Inserting a graded emitter, which consists ofGa-rich InGaAs and forms potential steps at the DB
structure’s emitter side, effectively reduced the operating bias voltage. We examined the effectiveness ofbarrier thickness reduction and graded emitter insertion. An example of the current-voltage characteristics of this novel RTD with 1.2-nm-thick barriers anda graded emitter is shown in Fig. 7. We have successfully obtained an extremely high JP of 2.4 × 106 A/cm2
with a PVR of 2 under a comparatively low bias
voltage of 0.8 V. To our knowledge, this is the highest
NTT Technical Review

Feature Articles

1.2
1
2

Output (arb. unit)

Current densirty ( x106 A/cm2)

2.5

1.5
1

PVR = 2

0.5
0

7 µW
0.8
0.6
0.4
0.2

0

0.2 0.4 0.6

0.8

1

1.2

Voltage (V)

0

0.5

0.75

1

1.25

1.5

Frequency (THz)

Fig. 7. Current-voltage characteristics of the RTD.

Fig. 8. Measured oscillation spectra.

JP ever reported. The current-voltage characteristics
indicate the formation of high-quality ultrathin barriers and heterointerfaces. The RTD oscillator’s measured spectrum for fundamental oscillation at 1.04
THz, which is the highest oscillation frequency everreported in a single solid-state device operating atroom temperature, is shown in Fig. 8. The output
power was 7 µW. Further optimization of the structural parameters should enable increases in the oscillation frequency and output power to meet thedemand for practical compact THz devices.

for Sub-terahertz and Terahertz Oscillators,” Jpn. J. Appl. Phys., Vol.
47, No. 6, pp. 4375–4384, 2008.
[3] T. C. L. G. Sollner, P. E. Tannenwald, D. D. Peck, and W. D. Goodhue,“Quantum Well Oscillators,” Appl. Phys. Lett., Vol. 45, No. 12, pp.
1319–1321, 1984.
[4] E. R. Brown, J. R. Söderström, C. D. Parker, L. J. Mahoney, K. M.
Molvar, and T. C. McGil, “Oscillations up to 712 GHz in InAs/AlSb
Resonant Tunneling Diodes,” Appl. Phys. Lett., Vol. 58, No. 20, pp.
2291–2293, 1991.
[5] H. Sugiyama, H. Matsuzaki, Y. Oda, H. Yokoyama, T. Enoki, and T.
Kobayashi, “Metal-organic Vapor-phase Epitaxy Growth of InPBased Resonant Tunneling Diodes with a Strained In0.8Ga0.2As Well
and AlAs Barriers,” Jpn. J. Appl. Phys. Vol. 44, No. 10, pp. 7314–
7318.
[6] N. Orihashi, S. Suzuki, and M. Asada, “One THz Harmonic Oscillation of Resonant Tunneling Diodes,” Appl. Phys. Lett., Vol. 87, No.
23, 233501, 2005.
[7] S. Suzuki, A. Teranishi, K. Hinata, M. Asada, H. Sugiyama, and H.
Yokoyama, “Fundamental Oscillation up to 831 GHz in GaInAs/AlAs
Resonant Tunneling Diode,” Appl. Phys. Express, Vol. 2, 054501,
2009.
[8] S. Suzuki, M. Asada, A. Teranishi, H. Sugiyama, and H. Yokoyama,“Fundamental Oscillation of Resonant Tunneling Diodes above 1 THz
at Room Temperature,” Appl. Phys. Lett., Vol. 97, No. 24, 242102,
2010.
[9] T. Kosugi, H. Sugiyama, K. Murata, H. Takahashi, A. Hirata, N.
Kukutsu, Y. Kado, and T. Enoki, “A 125-GHz 140-mW InGaAs/InP
Composite-channel HEMT MMIC Power Amplifier Module,” IEICEElectron. Express, Vol. 6, No. 24, pp. 1764–1768, 2009.
[10] H. Sugiyama, H. Yokoyama, A. Teranishi, S. Suzuki, and M. Asada,“Extremely High Peak Current Density of over 1 x 106 A/cm2 in InPbased InGaAs/AlAs Resonant Tunneling Diodes Grown by Metalorganic Vapor-phase Epitaxy,” Jpn. J. Appl. Phys., Vol. 49, 051201,
2010.
[11] S. Suzuki, K. Sawada, A. Teranishi, M. Asada, H. Sugiyama, and H.
Yokoyama, “Fundamental Oscillations at ~900 GHz with Low Bias
Voltages in RTDs with Spike-doped Structures,” Electronics Lett.,Vol. 46, pp. 1006–1007, 2010.

4. Conclusions
NTT and Tokyo Tech have had great success intheir collaborative development of RTD THz oscillators. Using precisely controlled semiconductor epitaxial growth and microfabrication technologies, wehave achieved fundamental oscillations above 1 THz
at room temperature through optimization of the RTD
layer structure. Further increases in oscillation frequency and output power are expected through further improvement of the oscillator structures, whichshould lead to a practical room-temperature compact
THz light source.
References[1][2]

R. Tsu and L. Esaki, “Tunneling in a Finite Superlattice,” Appl. Phys.
Lett., Vol. 22, No. 11, pp. 562–564, 1973.
M. Asada, S. Suzuki, and N. Kishimoto, “Resonant Tunneling Diodes

Vol. 9 No. 10 Oct. 2011

Feature Articles

Hiroki Sugiyama

Senior Research Engineer, Heterostructure
Devices Research Group, High-Speed Devices
and Technology Laboratory, NTT Photonics
Laboratories.
He received the B.S. and M.S. degrees in physics from Tokyo Institute of Technology in 1991
and 1993, respectively. Since joining NTT in
1993, he has been engaged in R&D of epitaxial
growth and characterization technology of III-V
compound semiconductors for ultrahigh-speed
electron devices. He is a member of the Japan
Society of Applied Physics (JSAP) and the
Physical Society of Japan.

Safumi Suzuki

Assistant Professor, Interdisciplinary Graduate
School of Science and Engineering, Tokyo Institute of Technology.
He received the B.E. degree in electrical andelectronic engineering and the M.E. and Dr.Eng.
degrees in electronics and applied physics from
Tokyo Institute of Technology in 2005, 2007, and2009, respectively. He has been an assistant professor with the Department of Electronics andApplied Physics, Tokyo Institute of Technology,
since 2009. He is currently engaged in researchon terahertz electron devices. He is a member of
JSAP.



Masahiro Asada

Professor, Interdisciplinary Graduate School of
Science and Engineering, Tokyo Institute ofTechnology.
He received the B.E., M.E., and Dr.Eng.
degrees in physical electronics from Tokyo Institute of Technology, in 1979, 1981, and 1984,
respectively. In 1984, he joined the Departmentof Physical Electronics, Tokyo Institute of Technology, as a Research Associate. During 1986–
1987, he was with the Physics Institute of Stuttgart University, Stuttgart, Germany, as a Research
Fellow of the Alexander von Humboldt Foundation. From 1988 to 1999, he was an Associate
Professor in the Department of Electrical andElectronic Engineering, Tokyo Institute of Technology. He has been a Professor in the Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology since1999. He is currently interested in high-frequency electron devices, especially terahertz devices
using nanostructures. He is a member of theInstitute of Electronics, Information and Communication Engineers, a Fellow of JSAP, and asenior member of IEEE.

NTT Technical Review

Feature Articles: Collaborations with Universities
Leading to Open Innovation in NTT’s R&D

Automatic Generation ofEnglish Cloze Questions
Based on Machine Learning
Tomoharu Iwata†, Takuya Goto, Tomoko Kojiri,
Toyohide Watanabe, and Takeshi Yamada
Abstract

We are developing a system that automatically generates multiple-choice cloze questions in English,
which we call MAGIC. By using machine learning techniques, MAGIC extracts the characteristics ofmanually generated questions and selects appropriate sentences for questions, determines words to beblanked, and generates multiple choices. This project is part of collaborative research and development
between NTT and Nagoya University.

1. Introduction
With the development of information and communications technology (ICT), e-learning has become
popular. One of its main benefits is that each user canlearn in accordance with his or her own achievementlevel, interests, and pace. However, we need to prepare a huge quantity of learning materials in order tosuit the levels and interests of a wide variety ofusers.
To resolve this problem, we are researching anddeveloping systems that generate learning materials
automatically. By fusing e-learning technology studied in Nagoya University and machine learning technology studied in NTT, we have developed a systemthat automatically generates multiple-choice cloze
questions for English, which we call MAGIC (multiple-choice automatic generation system for cloze
questions) [1]. Some examples of multiple-choicecloze questions are shown in Fig. 1. There were several reasons for focusing on this type of English questions. First, a lot of Japanese learn English, and English learning is in demand not only in Japan but allover the world. Second, this question type is common† NTT Communication Science Laboratories
Soraku-gun, 619-0237 Japanand used in TOEIC (test of English for international
communication) and university entrance examinations.
MAGIC takes English sentences as input. Users
may input just one sentence or multiple sentencesfrom newspaper articles and novels. MAGIC sorts thesentences in order of appropriateness for English
questions and outputs sentences containing blanks
and four options for each blank. Figure 1 shows anexample of MAGIC’s input and output.
MAGIC can be used for a variety of ways. First, byentering English sentences that match their own interests, users can learn while having fun. For example,
users who like football can learn English using football articles, and users can learn using novels byauthors that they like. Second, users can learn a typeof English that suits their study purpose. For example,
users can learn business English by using business
news articles, scientific English by using scientificpapers, and travel English by using travel guidebooks.
Third, users can overcome their weak points by generating and learning questions that test them.
The interests and goals for learning depend on
users, and they may change over time. Therefore, it isdifficult to prepare learning materials that meet thediverse interests and goals of all users.

NTT Technical Review

Feature Articles

Input

OutputMobile phones and the Internet have given rise to awide variety of new styles of communication, and it is
now possible for people to communicate much moreeasily and with much less effort. But as we strive forgreater convenience and comfort, we must also
ensure that ICT still makes a real contribution topeople's well-being. For example, new social issues
such as a lack of communication skills and theexclusion of older generations by the digital divide are
becoming increasingly prominent in the 21st century.
Our pursuit of rationality in telecommunications is notnecessarily compatible with irrational human
attributes such as the emotional responses of users.
The goal of a true communications environment
should be to enrich the human mind and experience.

Sentence #5
The goal of a true communications environment should
be to _____ the human mind and experience.
[1] enrich (answer) [2] style [3] send [4] play
Sentence #4
Our pursuit of rationality in telecommunications is notnecessarily compatible _____ irrational human
attributes such as the emotional responses of users.
[1] on [2] at [3] with (answer) [4] ofSentence #1
Mobile phones and the Internet have given rise to awide variety of new styles of communication, and it is
now possible for people to communicate _____ moreeasily and with much less effort.
[1] much (answer) [2] many [3] more [4] mostFig. 1. Input and output of MAGIC.

2. Rule extraction using machine learning
MAGIC has three components, which 1) sort sentences in order of appropriateness for English questions, 2) determine words to be blanked, and 3) generate multiple choices. The procedures of MAGIC areshown in Fig. 2. For these three components, we needrules for evaluating the appropriateness of English
questions, selecting words to be blanked, and generating choices, respectively. However, such rules are
not available, and humans do not generate questions
by following explicit rules.
MAGIC can automatically extract these rules byusing machine learning techniques, which find statistical rules from given training data by using computers. The training data for MAGIC are manually generated English questions. By analyzing hand-madequestions, we can extract rules for sorting sentencesand generating blanked sentences with their multiple
choices.
By changing the training data, we can change thequestion generating characteristics. For example, byusing TOEIC questions for the training data, we cangenerate questions that are similar to TOEIC questions. We can also increase the level of difficulty byusing high-level questions for the training.

Vol. 9 No. 10 Oct. 2011

Training data
(hand-made questions)
Input: sentences

Machine learning
1. Sorting sentences

2. Determining blanks

3. Generating choices

Statistical rules

Dictionary

Output: Cloze questions

Fig. 2. Procedures of MAGIC.

Feature Articles

Sentence 1

Sentence 3

Preference score: 10

Sentence 2

Sentence 5

Preference score: 9

Sentence 3

Sentence 1

Preference score : 5

Sentence 4

Sentence 2

Preference score: 3

Sentence 5

Sentence 4

Preference score: 1

Fig. 3. Sorting sentences on the basis of preferences.

Input
sequence

The

goal

be

shouldtoenrich

the

human

mind

Label
sequence

O

O

O

O

B

I

O

O

O

Fig. 4. Determining blanks by using sequence labeling.

3. Question generation procedures
In this section, we explain each component indetail.
3.1 Sorting sentences
Some of the input sentences might be appropriate
and some of them might be inappropriate for English
questions. For example, sentences that contain
important idioms and have important grammar structures are more appropriate for questions. MAGIC
sorts English sentences by comparing hand-madequestions (training data) and standard English sentences by using preference learning [2]. An example
is shown in Fig. 3. Preference learning enables us toassign high preference scores to sentences that are
similar to the training data. The similarities can becalculated by using word appearance frequencies andparts of speech (POSs) in the sentences. By sorting
input sentences in preference score order, users canlearn English with appropriate sentences for questions.



3.2 Determining blanks
Determining words to be blanked can be regarded
as a sequence labeling problem in machine learning.
The sequence labeling problem is to estimate an optimal label sequence for a given input sequence. In ourcase, the input sequence is a sentence (word se­­quence), and the output label sequence is a sequencethat represents the blank’s position. The label
sequence can be represented as shown in Fig. 4,
where B, I, and O are standard IOB2 tags indicating
the blank’s beginning and words inside and outside
the blank, respectively. With MAGIC, we use Conditional Random Field (CRF) [3], which has achieved
high performance in sequence labeling problems. As
features for CRF, we used words around the blankand their POSs. We confirmed that by using thesefeatures, we could select the words to be blanked
more accurately than by using conventional methods.
3.3 Generating choices
MAGIC generates multiple choices on the basis ofstatistical information and patterns obtained from thetraining data. We classify a set of choices into two
NTT Technical Review

Feature Articles

Blanked word and its POS
Type 2Type 1
Select POSs of choices(same POS as blanked word or not).

POS

Select pattern of choices(conjugation, prefix, postfix, etc.)

Generate choices using
dictionaries.

Generate choices in accordancewith the training data.

Fig. 5. Flow of choice generation.

types by the blank’s POS. The first type is a POS that
restricts words that can be chosen. For example, when
the preposition of is blanked, the alternative choices
are likely to be other prepositions such as to, in, andat. The words of an interrogative and auxiliary verb
are also included in this type as well as prepositions.
With this type, we can generate choices by considering
the POS and word probabilities. The second type is apart of speech that has patterns in conjugation,orthography, or meaning. This type includes verbs,
adjectives, and nouns. For example, patterns include
various conjugations of the same base word (ask,asked, asking, asks), the same prefix or postfix(defective, elective, emotive, active), and similar
meanings (told, said, spoke, talked). This type lets us
select a pattern in accordance with the POS and generate choices using dictionaries. The flow of choicegeneration is shown in Fig. 5.
4. Conclusion
We are developing a system for automatically gen-Vol. 9 No. 10 Oct. 2011

erating English cloze questions. We would like to sortsentences in order of user interests or difficulties [4],and this leads to personalized learning. We would
also like to extend the system so that it can generate
questions for learning other languages besides English and to generate learning materials in other subjects such as history and mathematics.
References
[1]

[2]

[3]

[4]

T. Goto, T. Kojiri, T. Watanabe, T. Iwata, and T. Yamada, “Automatic
Generation System of Multiple-choice Cloze Questions and Its Evaluation,” Knowledge Management & E-Learning: An International
Journal (KM&EL), Vol. 2, No. 3, pp. 210–224, 2010.
M. Collins and N. Duffy, “New Ranking Algorithms for Parsing and
Tagging: Kernels over Discrete Structures, and the Voted Perceptron,”
Proc. of the 40th Annual Meeting of the Association for Computational Linguistics, pp. 263–270, 2001.
J. Lafferty, A. McCallum, and F. Pereira, “Conditional Random
Fields: Probabilistic Models for Segmenting and Labeling Sequence
Data,” Proc. of the 18th International Conf. on Machine Learning, pp.
282–289, 2001.
T. Iwata, T. Kojiri, T. Yamada, and T. Watanabe, “Recommendation
for English Multiple-choice Cloze Questions Based on Expected Test
Scores,” International Journal of Knowledge-based Intelligent Engineering Systems, Vol. 15, No. 1, pp. 15–24, 2011.

Feature Articles

Tomoharu Iwata

Research Scientist, Learning and Intelligent
Systems Research Group, NTT Communication
Science Laboratories.
He received the B.S. degree in environmental
information from Keio University, Tokyo, theM.S. degree in arts and sciences from the University of Tokyo, and the Ph.D. degree in informatics from Kyoto University in 2001, 2003, and2008, respectively. His research interests include
data mining, machine learning, information visualization, and recommender systems. He received
the IPSJ (Information Processing Society ofJapan) Best Paper Award, FIT (Forum on Information Technology) Young Researcher’s Award,
and Funai Best Paper Award. He is a member of
the Institute of Electronics, Information andCommunication Engineers (IEICE) and IPSJ.

Takuya Goto

NTT DOCOMO.
He received the B.E. and M.I. degrees from
Nagoya University, Aichi, in 2007 and 2009,
respectively. His research subject was an English
learning support environment and automatic
generation of English questions. He is currently
interested in human-centered design.

Tomoko Kojiri

Associate Professor, Faculty of Engineering
Science, Kansai University.
She received the B.E., M.E., and Ph.D. degrees
from Nagoya University, Aichi, in 1998, 2000,
and 2003, respectively. From 2003 to 2004, she
was a research associate with the Graduate
School of Information Science, Nagoya University. From 2004 to 2007, she was a research
associate with the Information Technology Center, Nagoya University. From 2007 to 2011, she
was an assistant professor with the Graduate
School of Information Science, Nagoya University. Since 2001, she has been an associate professor with the Faculty of Engineering Science,
Kansai University, Osaka. In 2011, she stayed at
the Technical University in Graz as a guest
researcher for two months. Her research interests
include computer-supported collaborative learning, creative learning support, intelligent tutoring
systems, and human-computer interfaces. She
has received several academic awards including
the Outstanding Paper Award of ICCE/ICCAI2000 (International Conference on Computers in
Education, International Conference on Computer-Assisted Instruction), the Best Paper Award
of KES 2005 (Knowledge-Based & Intelligent
Information & Engineering Systems), and theOutstanding Poster Presentation Award of
ICCE2007. She is a member of IPSJ, the Japan
Society for Artificial Intelligence (JSAI), IEICE,
the Japanese Society for Educational Technology, the Japan Society for Information and Systems in Education (JSiSE), and the Asia-PacificSociety for Computers in Education.

Toyohide Watanabe

Professor, Graduate School of Information Science, Nagoya University.
He received the B.S., M.E., and Dr.Eng.
degrees from Kyoto University in 1972, 1974,
and 1985, respectively. Since 1975, he has
worked in Kyoto University and Nagoya University: as a research associate in the Data Processing Center, Kyoto University, from 1975 to 1987;
as an associate professor in the Faculty of Engineering, Nagoya University, from 1987 to 1994;
as a full professor in the same faculty from 1994
to 1997; as a professor in the Graduate School ofEngineering, Nagoya University from 1997 to
2003; and as a professor in the Department of
Systems and Social Informatics, Graduate
School of Information Science, Nagoya University, since 2003. In addition, from 2004 to 2008
he was concurrently the head director at theInformation Technology Center, Nagoya University. His current research interests include intelligent tutoring systems, computer-supported
collaborative learning, knowledge management,
and intelligent activity-support. He is a memberof the Association for Computing Machinery,IEEE-CS, the Association for the Advancementof Artificial Intelligence, Association for the
Advancement of Computing in Education, KES
International, IEICE, IPSJ, the Institute of Electrical Engineers of Japan, JSAI, the Japan Society for Software Science and Technology, JSiSE,
etc. He is also currently Editor in Chief of theInternational Journal of Knowledge and WebIntelligence. He has been a Fellow of IEICE
since 2004.

Takeshi Yamada

Senior Manager, Research Planning Department, NTT Science and Core Technology Laboratory Group.
He received the B.S. degree in mathematics
from the University of Tokyo in 1988 and the
Ph.D. degree in informatics from Kyoto University in 2003. He joined NTT in 1988. His
research interests are in machine learning, data
mining, and combinatorial optimization. He is amember of IEEE, IEICE, IPSJ, the Association
for Computing Machinery, and the SchedulingSociety of Japan.

NTT Technical Review

Feature Articles: Collaborations with Universities
Leading to Open Innovation in NTT’s R&D

High-presence Audio Live
Distribution Trial
Hiroshi Yamane, Akio Yamashita†, Koji Kamatani,
Masashi Morisaki, Tomomi Mitsunari, and Akira Omoto
Abstract

This article reports on a trial of live distribution of video featuring high-presence audio over optical
networks conducted in September 2010 and presents an evaluation of the results. With the spread of such
distribution, demand for high-presence replay is on the rise, and NTT WEST has been involved with
Kyushu University in joint research on high-presence video and audio.

1. Introduction
NTT WEST believes that one way of using optical
networks in the future will be live distribution, so it
has been involved in various undertakings to thisend.
On September 8, 2007, NTT WEST conducted alive broadcast of the “TCA Special 2007” from the
Takarazuka Grand Theater in Hyogo Prefecture to
two theaters: one in Tokyo and one in Osaka (TCA:
Takarazuka Creative Arts). And on December 24 in
the same year, NTT WEST conducted live broadcastsof the “Closing day of the Takarazuka Review Hanagumi Performance” from the Tokyo Takarazuka Theater to seven cinemas: four in Tokyo, two in Osaka,
and one in Nagoya. Unlike normal movie content,
this advanced live broadcast featured high-quality
content distributed via the network to a number ofcommercial cinemas [1].
Conducted jointly by TCA, NTT, and content holders, these trials aimed to provide an overall assessment of the potential of the future business of live
broadcasting over networks; address audio-visualquality issues, management structures, technicalissues, business models, and profitability; and gather
feedback from the content viewers themselves.
The configuration used for the trial (Fig. 1) involved
connections between NTT Communications’ optical† NTT WEST
Chuo-ku, Osaka, 540-8511 Japan

network (leased circuit services etc.) and NTT
WEST’s optical networks (local area network communications services), across which the multicasting
took place. The distribution equipment included an IP(Internet protocol) interface (NA5000), an encoder(HE5000), and a decoder (HD5000) (all products of
NTT Electronics Corporation); the distributed content was MPEG-2 (46 Mbit/s) video with stereo-quality audio. The equipment was continually monitoredfrom a web console to enable monitoring of the entire
distribution network and to enable communications
for troubleshooting between sites. An IRC (Internet
relay chat) server was set up as part of the platform toallow two-way chat-style communications from client personal computers at different sites, as well as an
Internet telephony system.
2. Technical issues with live distribution services
The 2007 trial showed that the MPEG-2 resolution(46 Mbit/s) enabled clear viewing of details such asindividual spangles on the Takarazuka Review costumes, indicating that there are no issues with resolution. However, when the camera panned sideways
during line dancing scenes and similar scenes, theimage on the screen became very difficult to watch—
it induced seasick-like feelings in those viewing in
the cinema’s front rows—so we concluded that conventionally shot TV content is not always suitable forthe big screen. Furthermore, although these cinemas
had 5.1 surround sound systems, distortion in the
NTT Technical Review

Feature Articles

Receivers: 7 cinemas

Source: theater
Projector
Datacenter
Decoder(HD5000)

Encoder(HE5000)
Wide-area Ethernet(≥100 Mbit/s)

Audio processor

Speakers

Fig. 1. 2007 live distribution trial.

stereo audio signals that had been encoded, compressed, and transmitted led to viewers complainingthat the sound was thin or no good.
Regarding video quality, resolutions higher than
MPEG-2 (46 Mbit/s) are possible, but they generally
lead to higher network costs, which prompts content
holders to ask whether it is possible, in terms ofactual business, to keep costs down without affecting
video quality.
To resolve the issue of nauseous feelings inducedby camera panning, we have introduced shooting
methods that take into account the constraints oflarge-screen projection by switching shots among
multiple cameras while eliminating panning as muchas possible. To address the issue of network costs, wehave been able to halve the video bandwidth while
maintaining the same video quality as MPEG-2 (46Mbit/s) by using MPEG-4 AVC/H.264 instead.
However, the audio quality problems still needed tobe addressed. There were four issues that needed tobe resolved: (1) audio quality at the time of recording,(2) audio quality during mixdown, (3) transmission
quality suitable for 5.1 surround sound, and (4) anaudio environment that can be replayed on 5.1 surround sound systems.
3. Joint research with Kyushu University
With a knowledge base in audio-visual engineeringand staging technologies, Kyushu University runs a“Culture Hall Management Engineer Training Program” training unit. The aims are to (1) teach personnel the skills to make and implement plans as part ofcommunity measures to promote local arts and culVol. 9 No. 10 Oct. 2011

ture, while making efforts to promote effective use of
local citizen halls and public centers using optical
networks; (2) promote regional development; and (3)bridge the information gap by distributing arts andcultural events that are held predominantly in the big
cities of Osaka and Tokyo, and thus expand opportunities to use content in local settings.
Since measures to distribute arts and cultural events
to local public halls via optical networks match NTT
WEST’s approaches and ideas for live distribution,and since both NTT WEST and Kyushu University
are working to spread live distribution via optical
networks, we have embarked upon joint research.
As part of this joint research, NTT WEST and
Kyushu University have considered ways to combine
knowledge and technologies to address the audio
quality problems identified in the 2007 trial and demonstrate solutions and have also considered ways topromote live distribution to public halls by using optical networks.
Specifically, research supervised by Associate Professor Akira Omoto of Kyushu University into thevisualization of reflected sound in an enclosed spaceby means of sound intensity measurement [2] hasbeen conducted for both the sender and receiver of
the audio signals. Through an understanding of thecharacteristics of the acoustic fields at both ends, thisresearch has provided us with new and optimized
recording and mixing techniques. By using Kyushu
University’s knowledge in combination with NTT
WEST’s optical networks and encoding technology
created through NTT’s R&D, and with the cooperation of NTT Learning Systems, we were able toachieve mixing optimized for the replay venue. For
Feature Articles

Tokyo Takarazuka Theater
CameraHD-SDI
Encoder(lossless)

Microphones

Analogaudio(13 ch)Distribution
systemAES/EBU(5.1 ch)Mixer

ATM line(40 Mbit/s)
Cineplex Makuhari
Projector
HD-SDI
Distribution
systemDecoder(lossless)
AES/EBU(5.1 ch) Audio processor

Speakers

AES/EBU: advanced encryption system, European Broadcasting Union
ch: channels
HD-SDI: high-definition serial digital interface

Fig. 2. 2010 high-presence audio live distribution.

the system demonstration, we were provided with
content from TCA in the same way as in the 2007
trial, and we were also assisted by Kadokawa Cineplex as the receiver of the high-presence live audio(replay venue). We conducted joint research with theparticipation of TCA and Kadokawa Cineplex [3].
4. High-presence audio live distribution trial
On September 12, 2010, we transmitted the Takarazuka Review––Snow Group performance of the final
performance of the “Natsuki Mizu Goodbye Show”
from the Tokyo Takarazuka Theater to test the highpresence audio distribution system (Fig. 2). Because
our aim was to find out if we could reproduce theoriginal audio from Tokyo Takarazuka Theater at the
replay venue, we used only one receiving site: theCineplex at Makuhari. The two sites were linked by a40-Mbit/s network connection in asynchronous transfer mode (ATM). We used the NA5000 as the IP
interface. We also used the new audio rate oriented

adaptive bit-rate video encoder/decoder developed by
NTT Network Innovation Laboratories; this codec
can control the bitrate between video and audio inreal time, and higher video quality is achieved bymaking use of extra bits saved by using lossless audio
compression. Since any audio quality degradation
should be avoided, we used MPEG-4 Audio Lossless
Coding (ALS) [4], to which NTT Communication
Science Laboratories is one of contributors in standardization activities.
Moreover, we used a highly efficient live distribution system developed by NTT Network Innovation
Laboratories, which served to ensure end-to-end reliability with error correction and IP packet encryption.
For picture quality, we chose to use the MPEG-4
AVC/H.264 (average 20 Mbit/s) format after evaluating the 2007 trial results. Furthermore, to compare
high audio presence with conventional systems, weused TCA’s commercial service to connect the Tokyo
Takarazuka Theater with another cinema (a conventional stereo-sound cinema) via the Business
NTT Technical Review

Feature Articles
1. Responses to the questionnaire
Cineplex Makuhari

Stereo-sound cinema

Number of responses

Response rate

157

57.1%

Number of responses

Response rate

103

33.4%

* Screen 7 (275 viewers)* Screen 2 (308 viewers)

2. What is your gender?
Cineplex Makuhari:
154 valid responses

Stereo-sound cinema:
101 valid responses
4%

11%
Male

Male

FemaleFemale89%96%

3. What is your age group?
Cineplex Makuhari:
154 valid responses
2%

Stereo-sound cinema:
103 valid responses

5%

30s

40s
24%

40s

50s
34%

60s

70s

70s

4. What was your impression of the impact of the sound?
Cineplex Makuhari: 153 valid responses
Moderately
strong

50s

23%

60s

25%

Strong

20s

18%

16%

30s

21%

Very strong

4%
Teens

20s

14%

1%

4%

Teens

9%

Stereo-sound cinema: 97 valid responses

Not verystrongIndifferent

Very weak

Weak

Very
strongModerately
strongStrongNot verystrongIndifferent

Very weak

Weak

16

65

20

36

14

2

0

9

28

17

34

6

3

0

10.5%

42.5%

13.1%

23.5%

9.2%

1.3%

0.0%

9.3%

28.9%

17.5%

35.1%

6.2%

3.1%

0.0%

IndifferentNotvery strong

Verystrong0%Moderately
strongStrong

10%

20%

30%

40%

50%

60%

70%

80%

90%

5. To what degree did you feel that the sound was surrounding you?
Cineplex Makuhari: 152 valid responses
Not very
Moderately
Weak
Indifferent
Very strong
Strongstrongstrong100%

Very weakVerystrong0%10%Moderately
strongStrong

20%

30%

40%

50%

60%

Stereo-sound cinema: 98 valid responses
Moderately
Very strong
StrongIndifferent
strongIndifferentNotvery strong

70%

90%

80%

100%

Not verystrong

Weak

Very
weak

17

52

35

30

15

3

0

13

27

14

30

9

5

0

11.2%

34.2%

23.0%

19.7%

9.9%

2.0%

0.0%

13.3%

27.6%

14.3%

30.6%

9.2%

5.1%

0.0%

Very
strong0%Strong

10%

20%

30%

Moderately strong

40%

50%

60%

Very
strongNot
Indifferent very strong

70%

80%

90%

100%

0%

10%

Moderately
strongStrong

20%

30%

40%

Not
very strong

Indifferent

50%

60%

6. How strongly did you feel as if you were actually in the Tokyo Takarazuka Theatre? (Please answer only if you have actually been there.)
Cineplex Makuhari: 149 valid responses
Stereo-sound cinema: 84 valid responses
Not very
Moderately
Moderately
Weak
Very weak
Very strong
StrongIndifferent
Indifferent
Very strong
Strongstrongstrongstrong

70%

80%

90%

Not verystrongWeak

100%

Very weak

23

42

39

27

14

3

1

13

24

23

15

11

5

3

15.4%

28.2%

26.2%

18.1%

9.4%

2.0%

0.7%

15.5%

16.7%

27.4%

17.9%

13.1%

6.0%

3.6%

Indifferent

Not verystrongVery strong

0%

10%

Strong20%

30%

Moderately strong

40%

50%

60%

Not
Indifferent very strong

70%

80%

90%

100%

7. What do you think of the entrance fee?
Cineplex Makuhari: 153 valid responses
VerysatisfiedSatisfiedModerately
satisfied

Very
Moderately
dissatisfied Dissatisfied dissatisfied

Indifferent

Verystrong0%10%Strong20%

Moderately strong

30%

40%

50%

60%

Stereo-sound cinema: 100 valid responses
Moderately
Very
Indifferent
Satisfiedsatisfiedsatisfied

70%

80%

90%

100%

Very
Moderately
dissatisfied Dissatisfied dissatisfied

9

25

20

53

38

6

2

4

7

3

39

34

9

4

5.9%

16.3%

13.1%

34.6%

24.8%

3.9%

1.3%

4.0%

7.0%

3.0%

39.0%

34.0%

9.0%

4.0%

Satisfied

0%

10%

Moderately
satisfied

20%

30%

Moderately
dissatisfied

Indifferent

40%

50%

60%

70%

80%

90%

Satisfied

100%

0%

10%

Moderately
dissatisfied

Indifferent

20%

30%

40%

50%

60%

70%

80%

Dissatisfied

90%

100%

Fig. 3. Questionnaire results.

Vol. 9 No. 10 Oct. 2011

Feature Articles

Ether-Wide service and feed high-definition video
with stereo audio to it. Furthermore, with the cooperation of NTT Cyber Space Laboratories, we createda questionnaire for viewers and statistically analyzed
the results to assess audio quality.
Regarding source audio recording, we sent a totalof 13 channels to the mixer, which included 9 channels from the Takarazuka Review venue audio and 4channels of independently added ambient audio,
which were mixed for the 5.1 surround sound system
at Cineplex Makuhari with the output fed to the lossless audio encoding equipment.
This setup enabled us to faithfully reproduce themixed audio signal at the Cineplex Makuhari venue.
A supervisor in the seating at Cineplex Makuhari wasable to relay information about the replayed audioback to the mixer at the Tokyo Takarazuka Theater inreal time to enable mixing adjustments as required.
As a result, viewers in the movie theater were able
to experience a similar atmosphere to the source
venue. They were naturally compelled to cheer andclap just as if they were really at the Takarazuka Theater––a reaction that was not observed during the2007 trial. In this way, we were able to successfully
overcome the limitations of conventional live network distribution and create a unified feeling between
the two venues.
5. Trial evaluation
We surveyed viewers about the high-presence audio
replay at Cineplex Makuhari and compared theresults with survey results collected from viewers at
the conventional stereo-sound cinema.
We received 157 responses from the 275 viewers at
Cineplex Makuhari (about 57.1%) and 103 responses
from the 308 viewers at the conventional cinema(33.4%). When we compared these results, we foundseveral noteworthy differences between the twogroups (Fig. 3).
In response to the question about the impact of thesound on a scale of 1–7, 66.1% of respondents at
Cineplex Makuhari rated the sound in the top 3, i.e.,

as very strong, strong, or moderately strong compared with only 55.7% for the stereo-sound cinema.
In response to the question, “How strongly did you
feel as if you were actually in the Tokyo Takarazuka
Theater?” 69.8% of respondents at Cineplex Makuhari selected very strongly, strongly, or moderately
strongly compared with 59.6% for the stereo-soundcinema.
The biggest difference between the two groups wasfor the question regarding entrance fees. 35.3% of
Cineplex Makuhari respondents said that they werevery satisfied, satisfied, or moderately satisfied and,including ones who answered indifferently, 69.6% ofthem were agreeable to the entrance fee. By contrast,
the corresponding figures for the stereo-sound cinema were 14% and 53%. These results indicate that thegeneral level of satisfaction was significantly higher
at Cineplex Makuhari.
6. Future plans
At NTT WEST, we plan to further analyze theseresults and establish business models for commercializing audio-visual lossless encoding and transmission and live distribution technologies with theaim of involving even more content holders to popularize live distribution services. Furthermore, we aim
to increase business efficiency by using optical networks and increase content security by providing asafe and reliable network while promoting research
into optical live distribution services.
References
[1]
[2]
[3]
[4]

http://www.ntt-west.co.jp/news/0711/071114a.html (in Japanese).
Y. Fukushima, H. Suzuki, and A. Omoto, “Visualization of ReflectedSound in Enclosed Space by Sound Intensity Measurement,” Acoustical Science and Technology, Vol. 27, No. 3, pp. 187–189, 2006.
http://www.ntt-west.co.jp/news/1009/100903a.html (in Japanese).
Y. Kamamoto, T. Moriya, N. Harada, and C. Kos, “Enhancement of
MPEG-4 ALS Lossless Audio Coding,” NTT Technical Review, Vol.
5, No. 12, 2007.
https://www.ntt-review.jp/archive/ntttechnical.php?contents=ntr2007
12sp2.html

NTT Technical Review

Feature Articles

Hiroshi Yamane

Manager, Solution Business Department, Corporate Marketing Headquarters, NTT WEST.
He received the B.S. degree in sociology andMBA degree from Momoyama Gakuin University (St. Andrew’s University of Japan), Osaka, in
1989 and 1996, respectively, and the Ph.D.
degree in engineering from Nara Institute of Science and Technology in 2001. He joined BRAINSR&D Center, NTT Business Communications
Headquarters, Tokyo, in 1989. He moved to NTT
WEST in 1999. He has developed many visualcommunication services such as the audio, visual, and communication systems design for
Kyushu National Museum of Japan (as a licensed
design engineer) and the 4K digital cinema international experiment. He received the 10th Telecommunications Advancement Foundation
Award in 1995. He is a member of the Institute ofElectronics, Information and Communication
Engineers and the Institute of Image Information
and Television Engineers of Japan.

Akio Yamashita

Assistant Manager, Services Creation Department, NTT WEST.
He graduated from the Faculty of Science,
Konan University, Hyogo, in 1999. He joined
NTT in 1999. Having gained experience in company system development in the Technology
Innovation Department, he is currently engaged
in optical distribution system (ODS) network
distribution joint research related to high-presence audio.

Koji Kamatani

Broadband Service Department, NTT Media
Supply.
He received the B.E. and M.E. degrees from
Kyoto University in 1998 and 2000, respectively.
He joined NTT WEST in 2000 and worked in the
Corporate Marketing Headquarters on planningand building corporate, municipal, and university
networks. After that he focused on live distribution service development for ODS and digital
cinema. He moved to the Broadband Service
Department in NTT Media Supply Co. in July
2011. He is currently engaged in designing andoperating Internet systems as a system administrator of an Internet service provider.

Vol. 9 No. 10 Oct. 2011

Masashi Morisaki

Services Creation Department, NTT WEST.
He graduated from the Faculty of Economics,
Shiga University in 1997. He joined NTT in
1997. While working in the Corporate Marketing
Department at Hyogo Branch, he was involved indeveloping systems for local government offices.
He is currently engaged in ODS network distribution joint research related to high-presence
audio.

Tomomi Mitsunari

Assistant Manager, Osakaminami Division,
NTT WEST-KANSAI.
She graduated from Ritsumeikan University
College of Law in 1999 and joined NTT in thesame year. Having gained experience in building
government and public office systems at the
Yamaguchi Branch, she worked on ODS network
distribution joint research related to high-presence audio. She became an Assistant Manager inOsakaminami Division, NTT WEST-KANSAI in
July 2007 and is currently engaged in the projectof agency business.

Akira Omoto

Associate Professor, Faculty of Design, Kyushu
University.
He graduated from Kyushu Institute of Designin 1987 and received the Ph.D. degree from the
University of Tokyo in 1995 for a thesis on an
active noise barrier. From 1987 to 1991, heworked as an R&D engineer at Nittobo Acoustic
Engineering Co., Ltd. In 1991, he was appointed
research associate at the Department of Acoustic
Design, Kyushu Institute of Design; he was made
Associate Professor in 1997. With the unificationof universities in 2003, he became Associate
Professor at the Faculty of Design, Kyushu University. His research interests include measurement, evaluation, and control of enclosed soundfields.



Feature Articles: Collaborations with Universities
Leading to Open Innovation in NTT’s R&D

CMOS LSI for Brain-machineInterface Used in
Bidirectional Communication
Akiyoshi Shimada† and Nobuhiko Nakano
Abstract

We introduce our approach to making an LSI (large-scale integration) chip for a brain-machine interface by integrating neuroscience technology developed in NTT Basic Research Laboratories (NTT BRL)
with LSI chip design and simulation techniques of Keio University. This LSI contains everything
required for bidirectional communication, which enables the brain-machine interface to communicate
with the brain on the molecular level when it is combined with a nano-bio device developed in BRL.

1. Introduction

2. Collaboration with Keio University

A brain-machine interface (BMI) links the external
world and the neural circuits in the brain, as shown in
Fig. 1. The feasibility of communication between thebrain and the external world was demonstrated by
Wilder Penfield, a Canadian brain surgeon, in the
1930s and 1940s [1]. He stated that “in the course ofoperations on the brain, electrical stimulation of thehuman brain, while patients are conscious, has sometimes activated the neuronal record of past experience.” [2]. These findings suggest not only that there
may be a correlation between the brain and memory
but also that the brain may be accessible from theexternal world. With today’s technology, neural activity is commonly evoked by electrical, magnetic, andchemical stimulation.
Studies related to controlling a robot or computerby using information in the brain made progress ataround the end of the twentieth century. Chapin et al.
showed that a robot arm can be controlled by neuralactivity in the cortices of a rat [3] and monkey [4].
Recently, BMI technology has been used for communication and device control for people with severe
motor disabilities [5].

NTT Basic Research Laboratories (NTT BRL) hasstudied information transmission of neurons, especially in the central nervous system. We have revealed
that neural activity in neurons cultured on a planar
multielectrode array (MEA) is influenced by electrical stimulation with an MEA-based multisite stimulation and recording system [6]. Although this system
was optimized for in vivo experiments, it is applicableto the BMI if the system is miniaturized. On the other
hand, the Nakano Lab. in Keio University has studied
the design and simulation of an LSI chip that consolidates analog and digital circuits. Since 2008, we
have been collaborating to achieve a BMI by combining these technologies through the intermediation andconstant encouragement of the Liaison Council of
NTT Corporation and Keio University.

† NTT Basic Research Laboratories
Atsugi-shi, 243-0198 Japan

3. LSI chip and MEA
3.1 Design and function
The human brain is thought to have more than one
hundred billion neurons. Each neuron receives synaptic inputs from several thousand other neurons. A
single neuron alone cannot evoke the electrical signals that are called action potentials. Furthermore,
electroencephalography shows that local activity inthe cerebral cortex is high when the brain processes
NTT Technical Review

Feature Articles

Brain

LSI chip for BMI

External world

Fig. 1. Brain-machine interface.

Recording circuit

Neural circuit

MEA

SwitchingcircuitMain amplifier
Stimulation circuit

Wireless circuit

Preamplifier

OutputInput

New
LSI chipFig. 2. Block diagram of LSI chip for BMI.

information. This information processing in the brain
is produced through the cooperation of many neurons. So the MEA is suitable for use with a BMI that
requires parallel information processing.
We have developed a complementary metal-oxidesemiconductor (CMOS) LSI chip with 8-channel
preamplifiers for data recording and a stimulus generating circuit [6] based on a multisite stimulation
and recording system [7].
The selection of the stimulation sites, their timing,and the applied stimulus waveforms are programmable, which results in vibration-free selection of any
combination of the eight electrodes (the MEA) for
stimulation. A block diagram of the final form of this
LSI chip together with the MEA is shown in Fig. 2.
The LSI chip consists of four parts: 1) a recording
circuit for measuring neural activity, 2) a stimulation
circuit for generating and applying a stimulus signal,3) a switching circuit and 4) a wireless circuit. The
first three circuits are on a 2.5 mm × 1.4 mm chip
fabricated by the CMOS process. We are now develVol. 9 No. 10 Oct. 2011

oping packaging for the main amplifier in the recording circuit and the wireless circuit.
3.2 Stimulation
Information from the external world is input to this
LSI chip by time-division multiplexing of eight channels by using a 4-bit digital parallel-to-serial converter. This makes it possible to stimulate multisitechannels independently. The maximum voltage output is ±700 mV with a biphasic waveform and theminimum pulse width is 20 µs.
3.3 Neural activity measurement
The neural activity of dissociated rat cortical neurons (embryonic day 18) cultured on a planar MEA(40 days in vitro) is shown in Fig. 3. The neural activity, which was measured as voltage signals with the
LSI chip via the MEA, was relatively small comparedwith the noise level. The noise comes from lines
between a preamplifier and an electrode because it isdifficult to seal them. So the noise level depends onFeature Articles

200 µV20 s
200 µV

nology [8]. The silicon substrate has microwells covered with a lipid bilayer containing reconstituted
membrane proteins. This device emulates the functions of a postsynaptic membrane and lets us measurechemical signals as electric signals when electrodes
are installed on the two sides of the lipid bilayer.

40 ms

5. Conclusions

Fig. 3. Neural activity measured with LSI chip.

the lengths of these lines. An LSI chip with a preamplifier allows a shorter line length when it is mounted
near the MEA. Moreover, it can evoke neural activity
and measure it through the same electrode by switching the stimulation and recording circuits. These
characteristics make it a suitable device for enablinga BMI to be attached to a body and exchange information via an MEA with low noise.

An LSI chip integrated with an artificial synapse
enables communication with neurons at the biomolecular level. This feature could provide an alternative
function for patients with nervous diseases or a newtool for discovering drugs that act directly on receptors.
Acknowledgments
This work is supported by the VLSI Design and
Education Center of the University of Tokyo in collaboration with Cadence Design Systems, Inc.

4. Interface for nano-bio device
Neural information is transmitted by means of theaction potential in one neuron and chemical signals
between two neurons across a synapse. When theaction potential arrives at a synapse called a presynaptic terminal, a chemical substance called a neurotransmitter is released. Neurotransmitters bind
receptor channels on a neighboring neuron called apostsynaptic neuron. Then, receptor channels open
and the current flow carried by ions enters and exits
through the receptor channels. When depolarizationof the postsynaptic neuron as a result of the current
flow reaches a certain threshold, an action potential isgenerated in the postsynaptic neuron.
Recently, nanotechnology has attracted attention inindustrial, medical, and scientific fields. In the fieldof neuroscience, this technology enables access from
one neuron to one protein molecule such as a receptor
channel, which is an essential component for neural
information transmission.
NTT BRL has studied an artificial synapse foraccessing neural information by means of a silicon
substrate by integrating nanotechnology and biotech-

References
[1]
[2]

[3]

[4]
[5]
[6]

[7]
[8]

W. Penfield and H. Jasper, “Epilepsy and the Functional Anatomy of
the Human Brain,” Boston, Little Brown and Company, 1954.
W. Penfield, “Activation of the Record of Human Experience: Summary of the Lister Oration Delivered at the Royal College of Surgeonsof England on 27th April 1961,” Ann. R. Coll. Surg. Engl., Vol. 29,
No. 2, pp. 77–84, 1961.
J. K. Chapin, K. A. Moxon, R. S. Markowitz, and M. L. L. Nicolelis,“Real-time Control of a Robot Arm Using Simultaneously Recorded
Neurons in the Motor Cortex,” Nat. Neurosci., Vol. 2, No. 7, pp.
664–670, 1999.
J. K. Chapin, “Using Multi-neuron Population Recordings for Neural
Prosthetics,” Nat. Neurosci., Vol. 7, No. 5, pp. 452–455, 2004.
J. J. Daly and J. R. Wolpaw, “Brain-computer Interfaces in Neurological Rehabilitation,” Lancet Neurology, Vol. 7, No. 11, pp. 1032–
1043, 2008.
M. Yamaguchi, A. Shimada, K. Torimitsu, and N. Nakano, “Multichannel Biosensing and Stimulation LSI Chip Using 0.18-µm Complementary Metal-oxide-semiconductor Technology,” Japanese Journal of Applied Physics, Vol. 49, No. 4, 2010.
Y. Jimbo, N. Kasai, K. Torimitsu, T. Tateno, and H. P. C. Robinson, “A
System for MEA-based Multisite Stimulation,” IEEE Trans. Biomed.
Eng., Vol. 50, No. 2, pp. 241–248, 2003.
K. Sumitomo, Y. Tamba, Y. Shinozaki, and K. Torimitsu, “Confinement of Fluorescent Probes in Microwells on Si Substrates by Sealing
with Lipid Bilayers,” Applied Physics Express, Vol. 3, No. 10, pp.
107001–107001-3, 2010.

NTT Technical Review

Feature Articles

Akiyoshi Shimada

Research Scientist, Molecular and Bio Science
Research Group, Materials Science Laboratory,
NTT Basic Research Laboratories.
He received the B.E. and M.E. degrees in engineering from Osaka University in 1993 and 1995,
respectively, and the Ph.D. degree in environmental and ocean engineering from the University of Tokyo in 2000. After joining NTT AccessNetwork Laboratories in 1995, he studied image
sensing and fiber-optic sensor technology. He iscurrently studying the interaction between excitatory and inhibitory neurons by using an MEA
and BMI. He received the IIP Equipment Division Award for Young Engineers from the Japan
Society of Mechanical Engineers in 1997 and theTechnical Award from the Japan Society for
Composite Materials in 2000. He is a member of
the Society for Neuroscience and the Japan Neuroscience Society.

Vol. 9 No. 10 Oct. 2011

Nobuhiko Nakano

Associate Professor, Faculty of Science andTechnology, Department of Electronics and Electrical Engineering, Keio University.
He received the B.S., M.S., and Ph.D. degrees
in electrical engineering from Keio University,
Kanagawa, in 1990, 1992, and 1995, respectively. In 1995, he was engaged in research at Keio
University as a Research Fellow of the Japan
Society for the Promotion of Science. In 1996, hejoined the Department of Electronics and Electrical Engineering, Keio University, as an instructor. His research interests include LSI/TCAD,
numerical simulation, and modeling. He is currently working on the design of an LSI chip for a
BMI.



Feature Articles: Collaborations with Universities
Leading to Open Innovation in NTT’s R&D

High-quality Software Development
Through Collaborations withMajor Universities in China
Xiaojun Wu†
Abstract

To achieve high-reality visual telecommunications, NTT Cyber Space Laboratories is conducting
research to obtain high-fidelity three-dimensional vision information. This article introduces collaborations in this field with several major universities in China and reviews software developed through thesecollaborations.

1. Introduction
In communications, images and videos have great
advantages over other media, such as audio and text
because they can be perceived and understood directly by people, so they can transfer a much greater
amount of detailed information. To achieve high-reality telecommunications, my colleagues and I at NTT
Cyber Space Laboratories are conducting research on
visual media in a wide range of fields, covering image
processing, image compression, and three-dimensional (3D) computer graphics (CG) [1], [2]. In recent
years, along with increases in the computing power ofcentral processing units, both high-resolution andhigh-quality digital cameras have become popular.
These days, ordinary people can send photographs
attached to messages from their mobile phones byusing a multimedia messaging service. Such services
have resulted from advances in both image processing techniques and the image sensors installed in
mobile phones. Meanwhile, it is widely recognizedthat high-reality visual telecommunication cannot be
achieved by just sending such visual images or videos. Techniques for understanding images are needed.
Specifically, it is necessary to understand the object
in the scene, what the object is doing, and even theobject’s purpose by processing and analyzing the† NTT Cyber Space Laboratories
Yokosuka-shi, 239-0847 Japan

captured images. In this article, I focus on humanmotion analysis and introduce several collaborative
projects in this field with major universities in
China.
2. Research themes on computer vision
2.1 Overview
Research in the field of computer vision (CV) has
become very popular in recent years. The aim is tounderstand the real world from photographs or videos. One of the ultimate goals of CV is to reconstruct
a complete 3D visual model of the visual experiencein common activities. That is, not only the shape but
also the textures and lighting environment are allreconstructed as high-fidelity models, which are justlike CG models. The difference between CG and CV
is that CV models represent portions of the real world
but CG models are artificial creations. In fact, it isstill very hard to reconstruct such 3D models from 2D
photos. We have had some limited success in reconstructing the 3D shape of a moving person undercertain conditions. We have also constructed a multicamera video capture studio as a platform for our 3Dmodeling research.
2.2 General approach
The basic method of reconstructing 3D shapes fromphotographs is explained below. It is called the shapefrom silhouette method or volume intersection
NTT Technical Review

Feature Articles

PA

PA
DA

PB
DA

S

S

C

C
VA
(a) Visual cone

VB

VA(b) Intersection of multiple visual cones

Fig. 1. S hape from silhouette. Here, C denotes a cube, which is an example
of a 3D object, S denotes a 2D screen, PA denotes a viewpoint in
3D space, DA denotes a 2D polygon on the screen, which is thesilhouette of the cube, and VA denotes the visual cone backprojected from the viewpoint PA. P B, D B, and V B denote thecorresponding meanings to PA, DA, and VA.

method.
(1)	Set up multiple cameras with multiple different
viewpoints. All the cameras should be synchronized to capture the object at exactly the sametime.
(2)	For each frame, capture multiple pictures fromdifferent viewpoints and calculate the object’s
silhouette in each picture. In this way, multiple
2D silhouettes can be obtained.
(3)	Back-project one 2D silhouette from a certain
viewpoint; this produces a 3D cone, which iscalled a visual cone. The object is inside thisvisual cone. (Fig. 1(a)).
(4)	Calculate all the visual cones from the multiple
2D silhouettes (Fig. 1(b)). Since the object is
inside all of the visual cones, the 3D shape of theobject can be calculated as the region where thevisual cones intersect. Such a 3D shape is just an
approximate model of the real object, but its
accuracy can be improved by increasing thenumber of cameras.
While the idea of shape from silhouettes is simple,
this method is powerful for 3D shape reconstructionof moving objects. In practice, the space is divided
into a large number of cubes, which are called voxels(volume elements), and the shape is represented by acertain number of voxels. Below, we consider a 3D
shape as such a group of voxels.
2.3 Trends of 3D shape reconstruction
Once we have obtained approximate 3D shapes, we
can then get much more advanced or enhanced visualVol. 9 No. 10 Oct. 2011

information. Three examples of 3D shape research
are introduced below.
(1) Refinement of the 3D shape
Research is being conducted on refining theapproximate representation of the true shape obtainedby the shape from silhouette method.
(2) High-fidelity texture reconstruction
In a real lighting environment, when an object is
captured from different viewpoints simultaneously,
the color value for the same part may differ among
pictures taken from the different viewpoints. Such
differences occur for various reasons, such as differences in camera sensing responses and surface reflections. While the differences among cameras can be
reduced by calibration and tuning, a lot of research is
focused on detecting the characteristics of surface
reflections and computing the lighting environments.
(3) 3D motion analysis
By introducing a 3D human skeleton model, we cancalculate both static and motion parameters of a 3D
body, which is represented by voxels, because thelength of each part of the skeleton and the rotation
angle of each joint can be estimated by just fitting the
3D shape, i.e., group of voxels, to the 3D skeleton
model. That is, such an estimation results in the capture of motion information just like a motion capturesystem. Such 3D-skeleton-model-based estimation isusually referred to as a markerless form of motion
capture; not requiring the use of markers is an advantage. Markerless motion capture systems can capturemuch more detailed motions of natural actions thanFeature Articles

Fig. 2. Basic motion estimation tool.

the traditional system because neither markers nor
special costumes (e.g., tights) are needed. However,their accuracy is still poor for practical usage andneeds to be greatly improved to reach a comparable
level.
As mentioned above, a lot of research focusing on
human-body 3D reconstruction in the CV field isbeing conducted to achieve the ultimate goal. In ourlaboratories, we are fortunate to have the advantageof doing voxel-based 3D human body reconstructionin our studio with multiple well-calibrated synchronized cameras. Such voxel-based 3D data is very
useful for all of the types of research mentioned
above.
3. Collaboration with universities
The abovementioned CV research trends are interesting hot topics. To speed up the progress of suchstudies, we are conducting international collaborations with major players in this field.



3.1 S
 hanghai Jiaotong University: markerless
motion capture
3.1.1 Proposal
We approached Prof. Yuncai Liu of Shanghai Jiaotong University in China, and as a result his teambecame our first partner. Professor Liu has worked
successfully in the USA and Japan as well as China,
where he currently leads a top-class CV team. He hasstudied human motion analysis and published papers
in several famous international conferences. He wasinterested in our themes and agreed to our proposal
for collaboration. As the first step, we decided to starta project to create a markerless motion capture system based on our voxel-based 3D shape reconstruction platform.
3.1.2 Development of basic toolTo get best performance out of both sides as quickly as possible, we decided to develop a basic tool first.
This tool is a software program that takes the voxelbased 3D shape as input and outputs 3D motion dataobtained by fitting to a 3D human skeleton model
designed by Liu’s team. The program’s input andoutput are shown in Fig. 2. For the 3D model-fitting
algorithm, we used one given in a published paper [3].
NTT Technical Review

Feature Articles

The program’s flow is described below.
The motion estimation is divided into two phases:
the initialization phase and the pose tracking phase.
In the initialization phase, the length of each part ofthe 3D skeleton model is determined and the skeleton’s pose is matched to the initial shape. In the posetracking phase, the previous pose is taken as input andthis input pose is adjusted to match the current shape;
the optimal result gives the current pose. Since it istechnically difficult to initialize the phase automatically, we decided to develop the pose tracking phasefirst while leaving the initialization phase to be done
manually. Thus, the problem could be defined as estimating all joint angles of the current shape by giving
the lengths of all parts and the previous angles of all
joints. The algorithm is described below, where t – 1
is the previous time and t is the current time.
(1)	Since all joint angles at t – 1 and all part lengths
are given, calculate the positions of all joints andparts at t – 1.
(2)	Consider a cylindrical area around each part.
Determine the radius of each cylinder so that thevoxels are included within as many cylinders as
possible by applying the 3D shape at t – 1 to theskeleton calculated in step (1).
(3)	For each joint, choose N values as rotation angle
candidates. As a result, we get a mixture of all
candidates, and each element of the mixture
represents a candidate pose. For each candidate
pose, by applying the 3D shape at t, calculate theerror in that candidate pose as the number ofvoxels outside the cylinders corresponding to
the candidate pose.
(4)	Choose the candidate pose with the lowest error
as the estimation result.
By implementing the above algorithm, we developed the first version of the 3D motion estimation
tool.
3.1.3 Automation of initialization phase
Since initialization phase was not implemented in
the basic tool, the next target was to automate it. In
fact, doing the initialization phase manually is areally hard and complicated task because the numberof parameter dimensions increases with the numberof joints. Manual initialization is obviously a bottleneck for a practical 3D motion estimation system.
Therefore, the project focused on automating the initialization phase. Both sides thought that it would be
impossible to achieve perfect automation for any
arbitrary pose, so we took a more practical approachand aimed to simplify the initialization task. The goal
was to develop an interactive initialization tool. That
Vol. 9 No. 10 Oct. 2011

is, the initialization phase was divided into several
steps. The processing for each step was automatedand manual interactive tuning was applied between
steps. The graphical user interface for this step-bystep initialization is shown in Fig. 3. The steps aredescribed in detail below.
(1) Head detection
Detect the head part by using a sphere model andfitting the sphere to the upper part of the 3D body
shape.
(2) Torso detection
Detect the torso part by fitting a cylinder model tothe part underneath the 3D body shape’s head detected in the previous step.
(3) Limb detection
Detect the positions of limbs by iterating the torso
detection algorithm.
While the idea of step-by-step detection is simple,
it is useful in practice as a means of developing tools
for further research. By avoiding direct parametertuning, we achieved much easier interactive tuning.
3.2 Z hejian University: application of estimated
3D motion to CG animation
While much work remained to be done on themarkerless motion capture developed through collaboration with Shanghai Jiaotong University to
improve the system performance, we next considered
the application of CG animation. To identify the possibilities of such applications, we conducted a collaborative project with the team of Prof. Xiaogan Jin
at Zhejiang University in China. Professor Jin hasstudied in Japan and is a leader in the CG field in
China. We proposed that his team should develop
high-reality human CG models. While applying the
motion data to the CG model, the joints of the CG
model must be deformed properly to achieved naturaland visually smooth motion. Jin’s team was perfectfor achieving such deformation. Tools to link the estimated 3D motion and the CG model were developed.
While the resulting synthesized motion was not
smooth enough, the project revealed issues related to
3D motion estimation. Both sides gained CG and CV
technical skills from each other.
3.3 Tsinghua University: face reconstruction
While pursuing our overall aim of high-quality 3D
reconstruction for the whole human body, we also
focused specifically on modeling the face in detail.
After surveying research on modeling emotions fromfacial expressions, we decided to contact Tsinghua
University, the top academy of science and engineeringFeature Articles

Fig. 3. Initialization by interactive tuning.

in China. Professor Guangyou Xu at Tsinghua University has been tackling emotion tracking for several
years and has developed high-quality libraries forfeature tracking. As the first step of emotion modeling, a tool for tracking the features of face images wasdeveloped through collaboration with Tsinghua University. This tool is being utilized to refine the facemodel.
4. Concluding remarks
China has several major universities conducting
top-class research and development. Our collaborations with Chinese universities have rapidly yieldedhighly useful tools. The successful development of
the markerless motion capture system enabled us towork on motion analysis of long sequences of movement. Furthermore, these collaborative projects have
led to the creation of a wide network of research colleagues. Collaboration enhances not only the qualityof actual developments but also the relationships
among researchers.



References
[1]

[2]

[3]

T. Osawa, X. Wu, K. Wakabayashi, and H. Koike, “3D Human Tracking for Visual Monitoring,” NTT Technical Review, Vol. 5, No. 11,2007.
https://www.ntt-review.jp/archive/ntttechnical.php?contents=ntr2007
11sf3.html
S. Ando, X. Wu, A. Suzuki, K. Wakabayashi, and H. Koike, “Human
Pose Estimation for Image Monitoring,” NTT Technical Review, Vol.
5, No. 11, 2007.
https://www.ntt-review.jp/archive/ntttechnical.php?contents=ntr2007
11sf4.html
K. H. Han and J. H. Kim, “Quantum-inspired Evolutionary Algorithm
for a Class of Combinatorial Optimization,” IEEE Trans. on Evolutionary Computing, Vol. 6, No. 6, pp. 580–593, 2002.

Xiaojun Wu

Research Engineer, Visual Media Communications Project, NTT Cyber Space Laboratories.
He received the B.S. degree in electrical andelectronic engineering and the M.S. and Ph.D.
degrees in informatics from Kyoto University in
1998, 2000, and 2005, respectively. Since joining
NTT in 2005, he has been engaged in CV
research focusing on 3D shape reconstruction of
the human body using multiviewpoint cameras.
He has also been working on motion analysis forthe last two years. He is a member of the Instituteof Electronics, Information and Communication
Engineers.

NTT Technical Review

Feature Articles: Collaborations with Universities
Leading to Open Innovation in NTT’s R&D

Secure Method of Managing
Digital Content in
Ubiquitous Computing Environment
Akihiro Tsutsui† and Tomoko Sawabe
Abstract

A research project for building a remote collaboration environment based on technologies for handlinglarge-scale digital content is being undertaken by NTT Network Innovation Laboratories. This article
briefly reviews collaborative research with Keio University on a secure method of managing digitalcontent in a ubiquitous computing environment.

1. Introduction
NTT Network Innovation Laboratories has developed a digital cinema system and related technologies based on ultrahigh-definition video coding andcontent delivery technologies. We are currently using
these technologies in research and development(R&D) of a networked remote collaboration environment and in its application for the creation of content
such as movies [1]–[3].
Keio University has developed several technologies
for digital content delivery through basic research on
digital media creation, editing, and usage. It is also
engaged in R&D of permanent archiving and digital
media handling.
In a collaboration program between NTT Network
Innovation Laboratories and Keio University, my colleagues and I are designing a platform that enables
secure remote access to large-scale digital media. We
are also planning demonstration experiments using
this platform. These goals can be achieved by applying the previous research outcomes and know-how
associated with digital content handling of both parties. Another aim of the collaboration program is toclarify the technical problems of building a network
supported cooperative work (NSCW) environment.
So far, in the program’s first year, we have investi† NTT Network Innovation Laboratories
Musashino-shi, 180-8585 Japangated an authentication mechanism that enables
secure and flexible access to digital content via a network. In this article, we discuss security issues related
to large-scale digital content.
2. NSCWNSCW is an advanced concept based on computer
supported cooperative work (CSCW). Comparedwith CSCW, the aim with NSCW is to build a distributed cooperative working environment that makes
maximum use of networks. NTT Network Innovation
Laboratories has developed several key technologies
for processing and transmitting ultrahigh-definition
images and videos stably and securely. We are now
striving to achieve an NSCW environment that consists of high-quality audio/video communication withhigh reality, effective data sharing, and interactive
work spaces among distributed workers. Some examples of the application of NSCW are shown in Fig. 1.
One example is collaborative film making, such as
digital cinema. Currently, digital cinema creation andediting processes are done all over the world as aresult of ongoing globalization, so they are conductedin a networked distributed environment. To promoteresearch on NSCW, it is essential to build practicalexperimental environments. By studying an actual
use case such as film making, we can consult withexperts in this area and clarify their requirements.
More comprehensive technologies are required for
NTT Technical Review

Feature Articles

Film making

CG/CADSound editing

Video editing
NSCW applications
Content creation/
distribution

Industrial design

Market review

Future network

Medical services
and education

Managed network for distributed
storage and cloud computing
Transcoding, media searching,lossless coding, streaming,
file transfer, etc.
Streaming

Distributed realtime
data processing

Interactive
communication

CAD: computer aided design
CG: computer graphics

Fig. 1. Application examples of NSCW.

building such an experimental environment, e.g.,content archiving and distribution. In addition, technical studies from the ubiquitous computing viewpoint are requiring in order to consider remote collaboration in various distributed networks.
3. Content and security managementin ubiquitous environment
The Internet is utilized in various business fields.
Therefore, information security must be ensured during content distribution. A major theme of this collaboration program is the security of digital content.
Currently, some security-sensitive remote collaborations that handle digital assets operate a safe working
space and use a dedicated leased line, which ensures
network security. However, excluding open networks,
such as the Internet, sacrifices the convenience andexpandability of the remote collaboration itself.
Many kinds of wired and wireless network accessservices are available nowadays. Though there may
be variations in the communication quality, we canget online anywhere anytime. In Japan, because of the
spread of broadband services using optical fiber,
high-speed network access is available in almost all
offices and homes at low cost. WiMAX and Long
Vol. 9 No. 10 Oct. 2011

Term Evolution (LTE) wireless network access services are provided in public in downtown areas,
which enables large-scale content distribution tomobile devices.
In this context, two keys to investigating a flexible
remote collaboration environment are ubiquitous
computing and cloud computing using open networks. If we assume remote collaboration over theInternet, it is important to create a platform thatenables collaborative work via the network anywhere.
Of course, communication quality and working circumstances are not uniform because there are various
types of access networks. However, content creation
can be divided up into many kinds of work. Each kind
has its own networking requirements. Enhancing theubiquitous features of remote collaboration can leadto improved efficiency of all the work.
Ensuring information security in the ubiquitousenvironment of the Internet is a difficult task. In particular, unauthorized access must be prevented andcopyright protection technologies are indispensable
for valuable content (e.g., commercial audio andvideo).
With today’s rapid development of cloud computing and business globalization, it is necessary to use
the Internet for remote collaboration. Therefore,Feature Articles

Enabling
technologies- Codec and data transfer for ultrahighdefinition images and videos- Distributed storage systems forlarge-scale digital content- Realtime image (video) processing,
network virtualization, etc.

Management
technologies- QoE-oriented user interface- Large-scale content management- Security (copyright etc.) management

Key technologies forremote collaboration

Various wireless access networks

The Internet

Ubiquitous computing environment
Various wired access networks

Various environments
QoE: quality of experienceFig. 2. Key technologies for remote collaboration environment in ubiquitous networks.

security will become more important in this researcharea in the future (Fig. 2).
4. Importance of authentication technology
Security is the key to handling valuable digital content in a ubiquitous computing environment. In particular, an access control method for digital content is
especially important. From the network security
viewpoint, there are several technologies for protecting digital content from illegal tapping, unauthorizedaccess, and tampering. These include encryption,authentication, and digital watermarking [4]. The
main focus of this article is authentication technology.
Robustness against unauthorized access and resistance to tampering are important features of authentication for digital content distribution. They enabledistribution of appropriate content to identified people. In terms of security, ideal content distribution
would be the delivery of specific content (containing
an embedded identifier) by hand from the copyrightholder to a user in a closed room. This would requireface-to-face confirmation and a physically closed
space for absolute authentication. Meeting both conditions in content distribution over a network is
impossible. They may be almost met by using highdefinition videoconferencing systems and network
security technologies. However, this approach isimpractical because it is costly. Thus, the general useof password authentication is currently a reasonable

solution. In addition, the trade-off between authentication strength and user-friendliness of the authentication process must be considered. The implementation and operational cost of an authentication mechanism should be balanced against the value of thecontent.
If the authentication process is complicated and difficult for users to understand, they may try to accesstarget content through illegal or unexpected methods.
In that case, authentication strength degrades drastically. We focus on this security hazard and describe
an easy implementation example of multifactor
authentication.
5. Multifactor authentication
Authentication via a network can be broken down
into identification, judgment, and authorization processes. In each process, the authentication strength
can be enhanced by using multiple methods andinformation. This is the concept of multifactor
authentication. For example, the combination of a
specific device and secret knowledge possessed byusers can act as a highly secure key for authentication. Using multiple communication methods canalso enhance authentication strength. For example,
some online banking transactions these days requireconfirmation by phone.
In particular, mobile phones are useful for multifactor authentication because they are widely used, areused predominantly by one individual, and have a
NTT Technical Review

Feature Articles

Face-to-face authentication (ideal)
We can achieve virtual face-to-face authentication by using highly
realistic communication provided by NSCW technologies.

Multifactor authentication must use currently available means.
Multifactor authentication(multiple networks)
Using functions ofmobile phones
Managed network 1

GPS
Fingerprint

Managed network 2

Near-fieldcommunication
Mobilephones/smart
phones

Personal computer etc.

Internet

Multifactor authentication(multiple networks)

User authentication/content
management server

Fig. 3. User authentication and multifactor authentication technologies.

specific identifier (e.g., phone number). Moreover,the physical hardware cannot be copied and the carrier (operator) can detect illegal usage and tamperingand some mobiles contain biometric sensors and GPS(global positioning system) functions. In addition,
mobile phones use closed carrier network services(telephone and social networking system (SNS) services), which are independent of other open networks
such as the Internet.
One existing example of multifactor authentication
for large-scale digital content management is the Arianna System [5]. It is a practical implementation
using the Internet (web service) and mobile phoneservices. However, it cannot support smartphones,
which are becoming increasingly popular. We areinvestigating and developing a new multifactor
authentication method using a smartphone as anauthentication device (Fig. 3). Our method combinesVol. 9 No. 10 Oct. 2011

multiple authentication keys (users’ secret knowledge), biometrics, and geographical information toenhance authentication strength.
6. Future work
NTT Network Innovation Laboratories is promoting research activities for creating an advanced
remote collaboration environment through NSCW.
The next step is to build an experimental testbed fordemonstration experiments on handling large-scale
digital content in networks. This will let us examine
key technologies such as content storage & archiving
and content transmission (Fig. 4). We are planning totest multifactor authentication technologies and demonstrate an actual remote collaborative application,such as film making.

Feature Articles

Distributed editing for large-scale digital content (digital cinema etc.)
Preview environment

Filming

CG/CADSound editing

Video editing

Content management system (using multifactor authentication)
Feasibility study on testbed network
Optical networking

Content management

Distributed storage and realtime dataprocessing for large-scale digital content

Fig. 4. Feasibility study of remote collaboration environment for content creation.

7. Conclusion
We think that multifactor authentication is suitablefor handling large-scale digital content in a ubiquitous computing environment on open networks. In
general, component technologies, such as authentication, encryption, and digital watermarking, arerequired for the security management of large-scale
digital content. Applying these technologies to an
actual remote collaboration system handling digitalcontent is a future challenge.
Standardization activities for encryption and digitalwatermarking are under way and de-facto standards
already exist. However, the standardization of authentication technologies is not yet mature. In particular,
discussion of the user interface is an open issue.
In this collaboration program between NTT Network Innovation Laboratories and Keio University,
we have so far focused on security for remote col-laboration and investigated a multifactor authentication mechanism using a mobile phone (a typicalubiquitous device). In the future, we intend to build atestbed and further investigate this topic.
References
[1]

[2]

[3]

[4]
[5]

D. Shirai, M. Kitamura, and T. Fujii, “4K Super High Definition
Video Streaming System Using JPEG 2000 Codec,” IEICE Technical
Report, Communication Systems, Vol. 107, No. 244, pp. 43–48, 2007
(in Japanese).
S. Y. Kim, M. Ogawara, T. Fujii, Y. Kamamoto, N. Harada, and T.
Moriya, “Requirements for Developing Ultra-realistic Live Streaming
Systems,” Proc. of the IEEE ISPACS 2009, pp. 175–178, Kanazawa,
Japan.
D. Shirai, M. Kitamura, T. Fujii, A. Takahara, K. Kaneko, and N.
Ohta, “Multi-point 4K/2K layered video streaming for remote collaboration,” Elsevier, Future Generation Computer Systems, Vol. 27,
No. 7, pp. 986–990, 2011.
B. Schneier, “Beyond Fear: Thinking Sensibly About Security in an
Uncertain World,” Springer, 2003.
http://www.dcin.or.jp/actives/ip003/c01.html (in Japanese).

NTT Technical Review

Feature Articles

Akihiro Tsutsui

Senior Research Engineer, Supervisor, NTT
Network Innovation Laboratories.
He received the B.E. and M.E. degrees in systems engineering from Kobe University, Hyogo,
in 1988 and 1990, respectively. Since joining
NTT in 1990, he has been researching programmable network devices, high-performance Internet protocols, and home networking. His current
interests include data management technologies
in networks.

Vol. 9 No. 10 Oct. 2011

Tomoko Sawabe

Senior Research Engineer, NTT Network Innovation Laboratories.
She received the B.S. and Dr.Eng. degrees
from Keio University, Kanagawa, in 1987 and1996, respectively. She joined NTT in 1987. She
has been engaged in research on parallel digital
signal processing, multi-DSP architectures, andsuper-high-definition image processing.

Feature Articles: Collaborations with Universities
Leading to Open Innovation in NTT’s R&D

Joint Research on
Anshin in Internet Usage
Taro Yamamoto†, Naoko Chiba, Fumihiko Magata,
Katsumi Takahashi, Hiroki Ueda, Naoya Sekiya,
Isao Nakamura, Morihiro Ogasahara,
and Yoshiaki Hashimoto
Abstract

NTT Information Sharing Platform Laboratories is conducting joint research with specialists in sociopsychology at the University of Tokyo and Toyo University to study anshin (安心) in Internet usage.
Anshin, which is often translated as peace of mind, security, or reassurance, is a vague concept with awide range of meaning. Therefore, we decided to focus first not on anshin itself but on fuan (不安),which has roughly the opposite meaning (anxiety) because anxieties are easier to recognize. We constructed a model of the anxiety generation process and conducted two investigations—a home-visit
investigation in Tokyo and an international investigation by telephone—and we put out a press release
describing proof of an unbridgeable gulf between anshin and safety. In this article, we outline our current
studies.

1. Introduction
Anshin (安心) is a kind of emotion or feeling inJapanese. It often translated as peace of mind, security, or reassurance, but it is a vague concept in Japanese with a wide range of meaning. This word is frequently used by the government, mass media, andmany companies in Japan. Many Japanese people
think that it is an important concept. However, methods of achieving anshin and also the concept ofanshin itself are not shared universally. One reason isthat anshin is basically a subjective feeling and thetrigger for it and amount of it felt vary from person toperson. Even the same person may feel differently insimilar situations [1].
Because we believe that it is possible to share, atleast partially, the objective and universal concept ofanshin, we began studying anshin, especially withregard to Internet usage. The Internet has become asocial infrastructure and demand for its availability† NTT Information Sharing Platform Laboratories
Musashino-shi, 180-8585 Japan

by both end users and suppliers is very high.
We think that trying to study anshin using only anapproach based on information technology (IT) is
inadequate, so we also applied a social-science
approach. NTT began a collaborative study with the
University of Tokyo, which was later joined by Toyo
University. The NTT team members are IT engineers
and the University members are social scientists.
Since the start of the project, the number of people in
the research team has grown, enabling us to conductsocial research from a wider range of viewpoints.
In this article, we describe our studies and present
the results. On the basis of the results of group interviews with 23 people in Tokyo on anshin and anxiety,we conducted a home-visit investigation with 500
people in Tokyo and an international telephone investigation of 3300 people in ten countries (330 in eachcountry). In this article, we do not define anshin precisely or use an English translation because it is sovague. On the other hand, fuan (不安) is a clearer
concept and its translation as anxiety is more accurate,
so in this article we do use the English word anxiety.

NTT Technical Review

Feature Articles

18- to 21-year-olds who
usually use mobile phones
30 points

Anxiety standardHigh

10 points
Group AGroup E
Young people oftodayGroup C

30 points
Low

High
Literacy standard

5 points
Group B

Group D
Low

Fig. 1. Characteristics of groups.

Anxietyfactor 1

Anxietyfactor 2

Anxietyfactor 3

Expectedproblem A

Expectedproblem A’e.g., invasion of privacy

Mental anguish?
OccursAnxiety

Continue

RemovedAnshin?

Fig. 2. Model of anxiety generation process.

2. Group interviews
Before investigating negative factors of anshin andthe correlation among them, we conducted groupinterviews about anshin and anxiety to help us design
appropriate questionnaires for use in the following
investigations. The interviews took place on September 17–19, 2008 (Wednesday–Friday) in Tokyo,
Japan. There were 23 people in five groups (A–E).
The characteristics of these groups in terms of anxiety and literacy are shown in Fig. 1. Each session
lasted two hours. The questions asked about cases inwhich the participants felt anshin or anxiety in their
daily lives and while using the Internet.
From these group interviews, we found that it is noteasy to obtain clear, adequate, and quick answers toquestions about cases of anshin. By contrast, relatively clear and quick answers tended to be obtained
to questions about cases of anxiety. Moreover, anshinVol. 9 No. 10 Oct. 2011varied from person to person. So, as our first step, we
decided not to study anshin directly but to study
anxieties. We believe that anxiety is a close antonymof anshin and that anxiety is easier to handle.
3. Anxiety generation process
3.1 Model
To study anxiety, we used the results of the groupinterviews to construct a model of the anxiety generation process in order to clarify how anxiety is generated (Fig. 2). This model includes the following definitions: 1) Anxiety is generated by expectations ofproblems (e.g., invasion of privacy). 2) There are factors that are the reasons for expecting problems andthere are also factors that strengthen the expectations
and anxieties. 3) There are also factors that weaken or
eliminate the expectations and anxieties. We called
these factors anxiety factors. In future, we intend toFeature Articles

refine and verify this model and also evaluate theanxiety factor candidates.

Table 1. Anxiety factor candidates.

3.2 Control of Internet anxiety
We think that controlling (reducing) anxiety canweaken the feeling of expecting trouble and leads toa kind of anshin. We also think that the anxiety factors
are determined by each type of expected trouble foreach Internet service. We selected anxiety factor candidates mainly on the basis of the group interview
results. They are listed in Table 1. We hope that
establishing a method of controlling anxiety will leadto anshin.
4. Home-visit investigation in Tokyo
Next, partially to verify the anxiety generation process model and to obtain facts about anxiety fromvarious viewpoints, we conducted a home-visit investigation of Internet anxiety [2]. The investigation took
place in February 2009 in Tokyo. It involved 500
people (aged from 15 to 69). The visited homes werechosen by random area quota sampling. The questions concerned anxiety when using the Internet.
4.1 Internet users and anxiety
We found that Internet users felt less anxiety about
Internet usage than non-users did (Fig. 3). The moretime they spent using the Internet, the less anxiety
they felt concerning security and Internet communication. People who wrote things and posted them on
the Internet (consumer generated media (CGM*)
users) felt less anxiety in their general Internet usage
than people who only read content on the Internet.
The more frequently people commented on SNSs, theless anxiety they felt about Internet communication.
These findings may indicate that anxiety decreases
with experience.
4.2 Usability and content of anxiety
Many people use online shopping despite having
strong feelings of anxiety (Fig. 4). This may indicatethat there is a trade-off between anxiety and usability.
The most common specific anxiety for general Internet use was the leakage of personal information(Fig. 5).
*



1

Character & feeling2

Confidence

3

Sense of intimacy

4

Likes & dislikes

5

Mob psychology

6

Controllability

7

Ability to estimate

8

Difference from ideal

9

Difference from daily life

10

Context

11

Importance

12

Probability of occurrence

13

Sympathy

14

Superiority & inferiority

15

Usability

16

Experience17

Knowledge

18

Information source

19

Insurance

20

Support21

Alternatives

22

Ability to troubleshootFeel high anxiety
Feel low anxiety
Internet non-users
14.8%(N=27)

Feel medium anxiety
Feel no anxiety
59.3%

25.9%
0.0%

Internet users(N=442)

47.5%

44.3%

5.0%
Sum (N=469)

3.2%
48.2%

5.5%

43.3%
3.0%

* No-choice rate for people who do not know because they
do not want to use the Internet.

Fig. 3. Internet anxiety for Internet users and non-users(in Tokyo).

CGM: The CGM studied in our two investigations differed. In
the Tokyo investigation, the targets were weblogs (blogs), social
networking services (SNSs), bulletin board services (BBSs), andvideo hosting sites. In the international investigation, the targets
were blogs, SNSs, and BBSs.

NTT Technical Review

Feature Articles

40%

20%

0%

60%

80%

100%

Unexpectedly high Internet charges∗∗∗
53.0%

Non-users (N=248)
Users (N=252)

33.2%

37.0%

34.2%

11.9% 2.0%

22.2%

6.6%

Phishing∗∗∗
66.4%

Non-users (N=248)

48.1%

Users (N=252)

21.7% 10.3% 1.6%
28.4%

17.7% 5.8%

One-click fraud∗∗∗63.2%

Non-users (N=248)

29.2%

46.9%

Users (N=252)

30.9%

6.7% 0.8% Feel high anxiety

16.0% 6.2%

Feel medium anxiety
Feel low anxiety

Fake billing∗∗∗
64.8%

Non-users (N=248)

44.9%

Users (N=252)

8.7% 0.8% Feel no anxiety

25.7%
29.6%

17.3% 8.2%

Unauthorized use of credit card details used for payment
69.4%

Non-users (N=248)
Users (N=252)

21.8%

7.5% 1.2%

58.8%

32.1%

7.0% 2.1%

57.1%

34.1%

7.9% 0.8%

Non-arrival of goods bought online∗
Non-users (N=248)
Users (N=252)

48.1%

37.4%

49.6%

42.9%

10.7%

3.7%

Damaged or incorrect goods received∗
Non-users (N=248)
Users (N=252)

37.9%

49.8%

6.7% 0.8%
8.2%

4.1%

Chi-square test (∗p<.05,∗∗p<.01∗∗∗p<.001)

Fig. 4. Online shopping users and anxiety (in Tokyo).

0.0% 10.0%

Monetary loss
Unexpectedly high Internet charges

30.0%

50.0%

60.0%

70.0%

80.0%

90.0%

25.0%
15.1%
19.4%

Leakage of personal information

76.6%
36.1%

Fraud
Spam email

59.9%

Fake billing
Vague anxiety

40.0%

29.0%

Misoperation of personal computer or mobile phone
Breakdown of personal computer or mobile phone

20.0%

37.7%
3.2%

Fig. 5. General Internet anxieties (in Tokyo).

Vol. 9 No. 10 Oct. 2011

Feature Articles

4.3 Damage experience and news experience
The amount of damage actually experienced bypeople is generally small. Even for spam emails andspam in blogs (also called blog spam or commentspam), which account for the highest percentage ofanxieties in Fig. 5, only 12.0% of the subjects wequestioned reported experiencing actual damage
from them. Although the values are really too small to
let us evaluate the correlation with anxiety, we nevertheless tried to evaluate the correlation, but we wereunable to find any significant correlation (the only
exception was unexpectedly high Internet charges).
By contrast, damage is extensively reported by thenews media. Our analysis of the results of the influence of news reports indicates that the more time
people spend consuming mass media news, especially newspapers, the more anxiety they feel about
security and Internet communication.

Japan, China, South Korea, Singapore, the UK, Germany, France, Finland, America, and Chile (330 ineach). They were contacted by random digit dialing.
The questions concerned Internet anxiety.
5.1 Unbridgeable gulf between anshin and safety
We publicly disclosed our findings in an NTT press
release in September 2010 [4]. It stated that Japanesepeople feel high anxiety about using the Internet
although they have less direct experience of trouble
than people in other countries. We showed, by using
real data, that there is an unbridgeable gulf between
anshin and safety. These results (Table 2) show that
there are a lot of Japanese who cannot use the Internetwith anshin only owing to safety concerns. Specifically, in terms of the percentage of people having
experience of exposure of own home address or telephone number on the Internet without permission,
Japan ranked low (9th out of 10 countries; 1.2%).
However, Japanese feel high anxiety despite having
little actual experience of damage (Japan: 2nd out of
10; 82.7%). In particular, Japanese women feel highanxiety (1st out of 10; 75.2%). Japan ranked 1st(65.2%) for people with anxiety about computerviruses without having any experience of damage.
Moreover, it ranked 2nd for anxiety about phishing,
unauthorized use of credit card details used for online
payment, and harmful content being seen by children
when browsing, again without any experience ofdamage (76.4%, 83.6%, and 77.9%, respectively).

5. International investigation by telephone
Despite obtaining the abovementioned findings
about Internet anxiety, we did not know whether they
represent universal characteristics or local peculiarities. Unlike anshin, which is an obscure concept andhard to translate, fuan can be translated from Japanese into English, so anxiety is a universal concept.
Therefore, we thought that an international comparison of Internet anxieties would be possible. To study
anxiety in Japan and also to study anshin indirectly,
we conducted an international investigation of ten
countries by telephone [3]. The interviews took placein January and February 2010. We interviewed 3300
people (aged from 15 to 69) in the largest cities in

5.2 Internet anxieties of specific countries
We analyzed the results by country to see if people
in different countries had specific anxieties. For gen-Table 2. Experience for exposure of personal information and anxiety (international investigation).
Rate for each country
No damage
No damageexperience
experiencebut anxiety

Anxiety

Rank among the 10 countries
No damage
No damageexperience
experiencebut anxiety

Anxiety

Japan

82.7%

98.8%

83.6%

2nd

2nd

3rd

USA

60.3%

94.5%

64.5%

6th

4th

7th

Chile

25.2%

99.1%

26.1%

10th

1st

10th

China

77.9%

86.1%

90.0%

3rd

10th

2nd

South Korea

83.6%

91.5%

91.5%

1st

8th

1st

Singapore

73.0%

91.5%

78.5%

4th

8th

4th

UK

62.4%

94.8%

67.0%

5th

3rd

5th

Finland

42.2%

93.6%

46.2%

9th

5th

9th

Germany

48.6%

92.4%

55.2%

8th

6th

8th

France

59.7%

91.8%

66.7%

7th

7th

6th

NTT Technical Review

Feature Articles

Table 3. Anxiety level, damage experience, and news experience for CGM trouble (international investigation).
Anxiety

Low

High
Much

Damage experience

Much

News experience

—

Much

LittleLittle—Abuse/violent language andteasing

South Korea,
China

Japan

USA

Finland

Exposure of personal
information

South Korea,
China

Japan

Damage by self-exposure of
China, Southown personal information
Korea, Singapore* CGM users only

eral use of the Internet, South Korea, the USA, andChina ranked high in that order while Japan was notplaced so high (5th out of 10 countries). We compared the ten countries in terms of the proportion ofpeople in the country having damage experience,news experience, and anxiety, for eleven specifictypes of Internet trouble such as fake billing. People
in China and Singapore had a lot of damage experience and high anxiety. Those in Germany had muchnews experience but low anxiety. People in Finland
had much damage and news experience but low
anxiety. People in Chile do not use the Internet much,
but like people in the USA they had little damage andnews experience and low anxiety. People in South
Korea did not have so much damage and news experience but had high anxiety. People in Japan had little
damage experience but much news experience andhigh anxiety about trouble.
5.3 Anxiety concerning CGM, information leakage, and children browsing harmful content
This section describes our findings concerning
CGM, information leakage, and children browsing
harmful content (Tables 3 and 4).
Higher anxiety about CGM was felt in South Korea,
China, Japan, the USA, and Singapore. By contrast,
lower anxiety about CGM was felt in Finland andGermany. Among the people of countries in the highanxiety column, South Koreans and Chinese had
experienced actual damage while Japanese had experienced little damage. Japanese generally had muchnews experience and Japan ranked 1st out of the 10
countries for the proportion of people having news
experience of three cases of CGM trouble.
For personal information leakage, people of Japan,
South Korea, and China had high anxiety, much mental anguish caused by incidents, and a high likelihoodof occurrence. By contrast, people of Finland, theVol. 9 No. 10 Oct. 2011

LittleMuch

LittleGermany

Finland, Germany
Japan

Germany

FinlandUK, and Chile had low anxiety, mental anguish, andoccurrence likelihood.
For browsing of harmful content such as information about drugs and violent and pornographic imagesby children, people in the ten countries selected“Many suppliers of harmful content are not adequately arrested” and “Many website managers do notdelete harmful content adequately” as being big problems. People in the UK and Japan thought that those
two problems were bigger than other problems. Japanese also thought that “many parents do not teachappropriate website browsing” was a big problem(Table 4).
6. Concluding remarks
We are studying anshin during Internet usage. Initially, we focused not on anshin itself but on anxieties
because they are easier to recognize. After conducting
preliminary group interviews with 23 people inTokyo, we conducted a home-visit investigation of
500 people in Tokyo and an international telephone
investigation of 3300 people in ten countries (330 ineach). We made a model of the anxiety generation
process, obtained some knowledge from our investigations, and put out a press release describing theunbridgeable gulf between anshin and safety. We
think that this research was persuasive because it was
joint research with the specialists in socio-psychology.
To confirm and strengthen the results of the international investigation, we conducted a second set ofgroup interviews with foreigners from nine countries
living in Japan (December 2010 to February 2011).
We are also conducting an Internet investigation
about anxieties for particular Internet services such as
Twitter. To obtain real opinions, this investigation
includes many free-answer questions. Some of theFeature Articles

Table 4. Problems in browsing of harmful content by children (international investigation).
Problem

1st

2nd

3rd

Japan
68.2%

USA
67.3%

4th

5th

6th

9th

10th

France
42.1%

Chile
9.4%

USA
58.8%

China
48.8%

Chile
22.1%

Germany
33.9%

France
29.4%

Chile
20.6%

China
52.1%

France
45.2%

Chile
34.2%

Singapore Germany
47.3%
59.7%

France
45.8%

Chile
20.3%

Germany
51.9%

France
45.2%

Chile
21.3%

High
accessibility

Finland
75.8%

UK
73.6%

Parents

Finland
80.6%

Japan
79.7%

UK
68.5%

Germany
63.6%

France63.3%

School

UK
70.6%

USA
62.1%

South
Korea
53.0%

Singapore
51.8%

Finland
50.6%

China
47.6%

Low arrest
rates

UK
83.9%

Japan
82.4%

USA
74.2%

South
Korea
71.5%

Finland68.2%

Germany Singapore
58.2%
55.5%

Websitemanagement

UK
84.8%

Japan
81.8%

Finland
78.8%

USA
76.1%

South
Korea
67.9%

China
62.4%

Average

UK
76.3%

Japan
71.5%

Finland
70.8%

USA
67.7%

South
Korea
64.9%

Singapore
57.7%

results are scheduled to be presented at the 2011
JASI-JSIS Joint Conference (Japan Association forSocial Informatics, Japan Society for Socio-Information Studies). In the future, we will verify and refine
the anxiety generation process model and evaluate
the anxiety factor candidates through user experiments and other means. After that, we will consider
solutions for controlling anxieties from both theoperation and technology viewpoints. We will also
conduct further studies on anshin.

Germany,
China
56.7%

Singapore
61.8%
South Korea,
Singapore
59.7%

Japan
45.5%

China
53.5%

References
[1]

[2]

[3]

[4]



8th

7th

South
Korea
72.4%

T. Yamamoto, N. Chiba, F. Magata, K. Takahashi, N. Sekiya, I. Nakamura, M. Ogasahara, and Y. Hashimoto, “Investigation on Anxieties
while Using the Internet to Study about ‘Anshin’,” Journal of Information Processing, Vol. 19, pp. 212–220, 2011.
Y. Hashimoto, I. Nakamura, N. Sekiya, and M. Ogasahara, “Harmful
Effects and Anxiety Related to Internet Usage,” Research Survey
Reports in Information Studies, Interfaculty Initiative in Information
Studies, The University of Tokyo, Vol. 26, pp. 27–80, 2010 (in Japanese).
N. Sekiya, Y. Hashimoto, M. Ogasahara, I. Nakamura, K. Takahashi,
F. Magata, T. Yamamoto, and N. Chiba, “International Comparison ofAnxiety for Using the Internet,” Proc. of 2010 JASI-JSIS Joint Conference, pp. 265–276, 2010 (in Japanese).
NTT press release (in Japanese).
http://www.ntt.co.jp/news2010/1009/100902a.html

NTT Technical Review

Feature Articles

Taro Yamamoto

Naoya Sekiya

Research Engineer, Security Management SE
Project, NTT Information Sharing Platform
Laboratories.
He received the M.S. degree from Hokkaido
University in 1994. Since joining NTT in 1994,
he has been engaged in research on information
security together with social studies (anshin on
the Internet). He is a member of the Information
Processing Society of Japan (IPSJ) and the Japan
Society for Socio-Information Studies (JSIS).

Associate Professor, Toyo University.
He graduated from Keio University (Faculty of
Policy Management) in 1998. He received the
M.A. degree from the University of Tokyo in
2002. He became an associate professor at Toyo
University in 2010. He specializes in the fields ofsocio-psychology (disaster information and environment information) and advertising. He is amember of the Japan Society for Corporate Communication Studies, the Social Psychology
Association of Japan, and JSIS.

Naoko Chiba

Isao Nakamura

Research Engineer, Security Management SE
Project, NTT Information Sharing Platform
Laboratories.
She received the M.S. degree from Tokyo Institute of Technology Graduate School of Sciencein 2000. Since joining NTT in 2000, she has beenworking on information security and security
social science. She is a member of IPSJ.

Professor, Toyo University.
He graduated from Gakushuin University (Faculty of Law) in 1987. He received the M.A.
degree from the University of Tokyo in 1991. He
became an assistant professor at Matsuyama
University in 1996. He became an assistant professor at Toyo University in 2003 and became aprofessor there in 2004. He specializes in thefield of socio-psychology (communication
media).

Fumihiko Magata

Morihiro Ogasahara

Senior Research Engineer, Security Management SE Project, NTT Information Sharing
Platform Laboratories.
He graduated from Chuo University (Facultyof Law) in 1992. Since joining NTT in 1992, hehas been engaged in research on information
security together with social studies. He is amember of the Japan Society of Security Management, the Information Network Law Association, and the Institution of Professional Engineers, Japan (Information Engineering).

Associate Professor, Kansai University.
He graduated from Doshisha University (Faculty of Law), Kyoto, in 1989. He worked for NTT
from 1989 to 2003. He received the M.A. degreefrom the University of Tokyo in 2005. He became
an assistant professor at the University of Tokyoin 2008 and an associate professor at Kansai
University in 2011. He specializes in the field ofsocio-psychology (Internet communication). He
is a member of JSIS.

Katsumi Takahashi

Yoshiaki Hashimoto

Executive Manager, Information Security Project, NTT Information Sharing Platform Laboratories.
He received the B.S. degree from Tokyo Institute of Technology in 1988 and the Ph.D. degreefrom the University of Tokyo in 2006. Since joining NTT in 1988, he has been working on information retrieval, data mining, cryptographic
protocols, information security, privacy protection, and security social science.

Professor, the University of Tokyo.
He received the B.A. and M.A. degrees fromthe University of Tokyo in 1978 and 1982,
respectively. He became an assistant professor at
the University of Tokyo in 1987 and a professor
there in 1999. He specializes in the fields of communication theory and socio-psychology. He is amember of the Japan Society for Studies in Journalism and Mass Communication and JSIS.

Hiroki Ueda

Senior Research Engineer, Supervisor, Security Management SE Project, NTT Information
Sharing Platform Laboratories.
He received the B.S. and M.S. degrees from
Osaka City University in 1992 and 1994, respectively. He joined NTT in 1994. He is presently
engaged in R&D of information security.

Vol. 9 No. 10 Oct. 2011

Regular Articles

Stripping-freePhysical-contact Connector
Yoshiteru Abe† and Junya Kobayashi
Abstract

We introduce a new physical-contact optical connector that uses a stripping-free connection method.
The connector’s assembly procedure does not require the coated optical fiber to be stripped or cleaved,
which facilitates assembly. We designed the connector structure and the shape of the fiber’s end toachieve physical-contact connection and developed a method for forming the required fiber endface.

1. Introduction
Optical fiber is being widely introduced as a communication medium to handle the expansion ofbroadband services, and many ways of connecting
optical fiber such as fusion splicing, mechanicalsplicing, and optical connectors have been developed
and are being used in FTTH (fiber-to-the-home) systems. Conventional connection methods achieve
good optical performance by aligning bare glass
fibers after their coatings have been removed. All ofthese connection methods require careful handling of
the bare glass fiber, which is fragile. This has led todemand for a method of connecting coated fibers that
does not require a stripping process. Such a strippingfree fiber connection method would also enable us tosimplify the assembly procedure. However, the concentricity error between the core and coating diameterof the coated fiber causes a large misalignment
between the mated fiber cores.
In this article, we introduce a new stripping-free
optical connector that enables us to achieve a physical-contact (PC) connection and facilitate assembly.
We also present experimental results for PC connection with a low connection loss.
2. Principle of stripping-free PC connector
A cross-sectional view of the new connector is† NTT Photonics Laboratories
Atsugi-shi, 243-0198 Japanshown in Fig. 1. This connector has a ferrule and a
split sleeve to make it compatible with the existingSC [1] and MU [2] connectors. To achieve a PC connection, axial compression force is required between
the mated fiber endfaces. We used the axial compression force generated by a buckled fiber to simplify theconnector structure. As shown in Fig. 1(a), the fiber
end protrudes from the ferrule end and the fiber isfixed to the clamp part. This structure enables us tobuckle the fiber inside the flange when we connect
the ferrules, as shown in Fig. 1(b). The buckling force
can be controlled by setting the length of the buckled
section of fiber (buckling length) [3].
We designed the coated fiber alignment structure toachieve a low connection loss. The conventional ferrule is designed so that the glass fiber is inserted only
after its coating has been stripped off. Therefore, we
designed a new ferrule for the new stripping-free connector, as shown in Fig. 2. It consists of an externalpart with a microhole to align the glass fiber and acoating-hole part to align the coated fiber, as shownin Fig. 2(a). The external part has the same outer
diameter as the conventional ferrule. When the coatedfiber is inserted into the ferrule, the fiber end reaches
the microhole located at the ferrule end through thecoating-hole. When the fiber is pushed into themicrohole, the fiber coating is pushed back slightly at
the microhole’s entrance and only the glass enters the
microhole, as shown in Fig. 2(b). The new connector
enables us to obtain the same low connection loss asa conventional connector.

NTT Technical Review

Regular Articles

Protruding fiber
Coated fiber

Split sleeve

FerruleFlangeClamp part(a) Before connection

Buckled fiber

Buckling length(b) When connected

Fig. 1. Cross-sectional view of connector.

External part
Coated fiber

Microhole
Coating-hole part(a) Before connection

Glass fiber(b) When connected

Fig. 2. Cross-sectional view of ferrule.

3. Fiber endface forming technique
We devised a new technique for forming therequired fiber endface. This technique does not
Vol. 9 No. 10 Oct. 2011

require the cleaver, which is a special tool, used in theconventional fiber preparation technique. The coatedfiber is cut with an ordinary tool such as wire cutters.
The new technique forms this cut fiber endface into aRegular Articles

Cut fiber end
MotorAbrasive film
Fiber holder(a) PhotographAbrasive film

Sharpened fiber end

Motor

L

Coated fiber

Radius of curvature RdFiber holder
Polished fiber end

Fig. 3. Fiber end shape.
(b) Schematic diagram

Fig. 4. Fiber endface forming tool.

curved polished endface that enables us to achieve a
PC connection, as shown in Fig. 3. It comprises a
sharpening process and a polishing process. The
sharpening process is designed to eliminate thecracked fiber end produced by the blade of the wire
cutters when the coated fiber is cut. The polishingprocess is designed to create a curved fiber endface
for PC connection.
A photograph and schematic diagram of the endface forming tool for the sharpening and polishingprocesses are shown in Fig. 4. The tool consists
mainly of an abrasive film, motor, and fiber holder.
The fiber is held mechanically in the fiber holder.
When the fiber is moved toward the abrasive film, thefiber end makes contact with the film and is pressedagainst it by the buckling force of the bent fiber. The
motor rotates the abrasive film, which polishes thefiber endface.
4. Fiber endface design
We designed the fiber endface shape for PC connection in order to determine the process conditions
required for fiber endface forming. We calculated theaxial compression force Fp needed to achieve PCconnection with single-mode fibers (SMFs) with acurved endface. Fp is expressed as a function of theradius of curvature of the fiber endface R [4] by
3(1)
Fp= 4a E2 ,
3(1–v )R
where a is the core radius, E is the Young’s modulus,
and n is the Poisson’s ratio of the fiber. The calculated
results are shown in Fig. 5. The required Fp value
increases as R decreases. Applying our previous findings that the estimated maximum axial compression
force obtainable with a buckled fiber is 0.9 N [5], we
determined from Fig. 5 that an axial compression
force of less than 0.9 N requires a fiber endface witha radius of curvature of more than 23 μm.

5. Processing conditions for forming
coated fiber endface
First, the end shape of a fiber cut with wire cutters
was estimated. When a coated fiber is cut with wire
cutters, the fiber end is cracked by the cutter’s blades.
NTT Technical Review

Regular Articles

Axial compression force
for PC between SMF cores (N)

2.0

1.5

1.0

0.5

0

0

50

100

150

Radius of curvature (µm)

Fig. 5. Dependence of axial compression force on radius of curvature.

Vol. 9 No. 10 Oct. 2011

Cracked fiber length

Fig. 6. Photograph of cut fiber end.

30

Number of samples

Samples: 90
Average: 0.214 mm
Maximum: 0.399 mm
σ: 0.094 mm
20

10

0

0

A photograph of the fiber end after we cut the coatedfiber and removed the coating to measure the cracked
length accurately is shown in Fig. 6. We measured thecracked lengths of the cut ends of 90 fibers after wecut the coated fibers with wire cutters (Fig. 7). The
average cracked length was 0.214 mm with a standard deviation s of 0.094 mm. From this result, weestimated that the maximum cracked length likely tooccur in practice is about 0.5 mm (average + 3s). The
sharpening process eliminates the cracked end by
reducing the fiber length, as shown in Fig. 8. Therefore, we designed the sharpening process to shorten
the fiber by more than 0.5 mm in order to ensure thatthe formed fiber endface is not cracked.
In the sharpening process, the shortened length ofthe coated fiber is determined by the processing time,
the grain size of the abrasive film, and the shape ofthe bent fiber (bending shape). The bending shape isdetermined by the length of the fiber protruding fromthe fiber holder L and the distance between the abrasive film and the fiber holder d, as shown in Fig. 4. We
measured the relationship between the shortened
length of the coated fiber and the processing conditions when the forming tool was used. Here, the processing time and bending shape were varied. The
abrasive film’s grain size was 40 μm. The distance
between the abrasive film and fiber holder was 10mm. The experimental results that we obtained forthe shortened length of coated fiber are shown in
Fig. 9. The shortened length increased with increasing processing time and L value. The results indicatethat we can achieve a shortened length of more than

0.1
0.2
0.3
Cracked fiber length (mm)0.4

Fig. 7. Cracked fiber lengths.

Regular Articles

160

Cut fiber end

Shortened length
Sharpened fiber end

50

120
40
Return loss (dB)Fiber endface radius of curvature R (mm)Cracked length

100

30

R
60

Fig. 8. Sharpening process for forming fiber end.
20

0

0.1

0.2

20
0.3

Shape parameter L -d (mm)
1.0

Max.
Ave.
Min.

Shortened length from cut end (mm)0.8

Fig. 10. D ependences of radius of curvature and returnloss on fiber shape parameter.

L: 11.7 mm, d: 10 mm
L: 10.7 mm, d: 10 mm

0.6

0.4

0.2

0

0

30

60

90

120

150

Time (s)Fig. 9. Dependence of shortened length on processing
conditions.

0.5 mm by controlling the bending shape and processing time.
The sharpened endface is polished by using theforming tool, as shown in Fig. 4. The polished end

face is formed by using the same configuration as in
the sharpening process simply by changing the distance between the abrasive film and fiber holder. In
the polishing process, L is smaller than in the sharpening process. A slightly bent fiber enables us to form
the sharpened endface into a convex endface. We
measured the relationship between the fiber’s bending shape and the radius of curvature of the convex
endface when we changed the bending shape. An
abrasive film with a grain size of less than 1 μm wasused. The distance between the abrasive film andfiber holder was 10 mm. Our experimental results forthe radius of curvature of the polished endface areshown in Fig. 10. They reveal that we can achieve thetarget radius of curvature of more than 23 μm by controlling the bending shape. We measured the returnloss when we connected the polished endface using
the axial compression force, as shown in Fig. 10. We
found that the polished endface achieved PC connection with a return loss of more than 40 dB when weused a shape parameter L − d of less than 0.2.
6. Optical performance
We prepared a connector having a 100-μm-long
microhole and a flange with a buckling length of
NTT Technical Review

Regular Articles

15
Wavelength: 1.31 µm
Samples: 20
Ave.: 0.16 dB
Max.: 0.31 dB
Min.: 0.03 dB
σ: 0.09 dB

5

0
0

0.1

0.2

0.3

0.4

Number of samples

Number of samples

10

10

5

0
35

0.5

Connection loss (dB)

Wavelength: 1.31 µm
Samples: 20
Ave.: 46 dB
Max.: 52 dB
Min.: 42 dB
σ: 2.5 dB

40

45
50
Return loss (dB)55

60

Fig. 11. Connection loss histogram.

Fig. 12. Return loss histogram.

8 mm according to the PC connection design. We
measured the optical performance of SMFs with endfaces formed with the forming tool. We confirmedthat when the coated fiber was inserted into themicrohole, the coating was pushed back and only the
glass entered the microhole in accordance with design
shown in Figs. 1 and 2. Histograms of the connection
and return losses for 20 pairs of connected fibers areshown in Figs. 11 and 12, respectively. The connection losses for SMFs were less than 0.31 dB with anaverage value of 0.16 dB and standard deviation s of
0.09 dB. The minimum return loss was 42 dB, which
confirms that all the connected fibers achieved PC
connections. The results meet the performancerequirements stipulated in IEC 61753-2-1, which sets
the performance standard for SMF connection for an
uncontrolled environment.

stripped and cleaved, so it facilitates connector
assembly. A new method of forming the fiber endface
enables us to achieve PC connection. In laboratory
experiments, the stripping-free connector has
achieved PC connection with a return loss of morethan 42 dB and average connection loss of 0.16 dB.
References
[1]
[2]
[3]
[4]
[5]

7. Conclusions
We introduced a new physical-contact (PC) opticalconnector that does not require a coated fiber to be

Yoshiteru Abe

Senior Research Engineer, NTT Photonics
Laboratories.
He received the B.E. degree in electrical engineering, M.E. degree in electronic device engineering, and Dr.Eng. degree in electrical engineering from Kyushu University, Fukuoka, in
1996, 1998, and 2005, respectively. Since joining
NTT Opto-electronics Laboratories, Ibaraki, in
1998, he has been engaged in research on opticalfiber connectors. He is a member of the Instituteof the Electronics, Information and Communication Engineers (IEICE).

Vol. 9 No. 10 Oct. 2011

E. Sugita, R. Nagase, K. Kanayama, and T. Shintaku, “SC-type singlemode Optical Fiber Connectors,” Journal of Lightwave Technol., Vol.
7, No. 11, pp. 1689–1696, 1989.
R. Nagase, E. Sugita, S. Iwano, K. Kanayama, and Y. Ando, “Designfor MU-type Single-mode Miniature Optical Connector,” IEICE
Trans. Electron., Vol. E81-C, No. 3, pp. 408–415, 1998.
S. Timoshenko, “Strength of Materials, Part II, Advanced Theory andProblems, Third Editions,” New York: D. Van Nostran Company, Inc.,
pp. 145–152, 1956.
S. Timoshenko and J. Goodier, “Theory of Elasticity,” McGraw-Hill,
New York: D. Van Nostran Company, Inc. 1951.
Y. Abe, M. Kihara, M. Kobayashi, S. Matsui, S. Asakawa, R. Nagase,and S. Tomita, “Design and Performance of Field Installable Optical
Connector Realizing Physical Contact Connection without Fiber
Endface Polishing,” IEICE Trans. Electron., Vol. E93-C, No. 9, pp.
1411–1415, 2010.

Junya Kobayashi

Senior Research Engineer, Supervisor, NTT
Photonics Laboratories.
He received the B.S. and M.S. degrees inchemical process engineering from Hokkaido
University and the Ph.D. degree in materials
chemistry from Tohoku University, Miyagi, in
1986, 1988, and 1999, respectively. He joined
NTT LSI Laboratories in 1988. He is currently
engaged in research on polymer waveguides for
optical device applications. He is a member of
the Japan Institute of Electronics Packaging and
IEICE.



Regular Articles

Optical Power Budget Enhancement
Technologies for Long-reach
GE-PON System
Hiroshi Kimura†, Takuro Matsumoto, Satoshi Shimazu,
Shoichiro Yamashita, and Jin Yamasaki
Abstract

This article describes technologies for enhancing the optical power budget of the Gigabit Ethernet
passive optical network (GE-PON) system. The design goal is to significantly extend the fiber-to-thehome (FTTH) service area in a cost-effective manner. Following the development of enhanced opticalline terminals in 2009, work to enhance optical network units was completed this year. These technologies
enhance the optical power budget of the GE-PON system to 37 dB, which makes this system one of thelongest-reach systems in the world. These enhancements enable us to deploy FTTH to rural areas
economically.

1. Introduction
Fiber-to-the-home (FTTH) services, such as B
FLET’S and FLET’S HIKARI NEXT, have been
widely deployed in Japan, and the number of the customers exceeded fifteen million this year. However, it
is difficult to provide FTTH services to areas far fromthe central office because of the limit on the maximum optical power budget between the optical line
terminal (OLT) in NTT’s central office and optical
network units (ONUs) in customers’ homes.
In this article, we describe a long-reach Gigabit
Ethernet passive optical network (GE-PON) systemthat offers an enhanced optical power budget between
the OLT and ONUs. It enables further economical
expansion of FTTH coverage areas.
2. Power budget and optical signal attenuation
The transmitter and receiver of an optical fiber system must be designed taking into consideration the
expected attenuation of the optical signals. Because a† NTT Access Network Service Systems Laboratories
Yokosuka-shi, 239-0847 Japan

PON uses optical splitters in the network, the opticalattenuation is expected to be high, as shown in Fig. 1.
Therefore, the PON requires a higher optical powerbudget than the conventional point-to-point system.
E-PON, which was standardized as IEEE 802.3ah,
which specifies 1:16 optical splitting, has a powerbudget of 26 dB for a 20-km span [1]. This value isbased on the ideal optical path.
3. Optical power budget ofNTT’s GE-PON system
Even after the release of IEEE 802.3ah, we continued our access network development and consideredusing a splitting ratio of 1:32 and treating the nonideal optical paths of actual optical networks. In
2004, NTT developed a GE-PON system with an
optical power budget of 29 dB. Its 7-km span with a
1:32 optical splitting ratio covers more than 90% of
the access networks in Japan.
4. Development of long-reach GE-PON system
For further FTTH service area expansion, a costeffective GE-PON system with a span of greater than
NTT Technical Review

Regular Articles

Schematic of access network
A

ONU-A

A

B

C

A

B

C

Central office

PC
B

ONU-B

ONU-C

B

A

C

B

C
OLT

PC
C

A

A

B

C

Connection point
Optical splitter(with 32 branches)

Connection point

PC

Relation between optical power budget and optical attenuation loss
(1) Loss in optical fiber(2 dB)Low(2) Loss at eachconnection point(1 dB)

Power budget: 26 dB(( 4 ) – ( 5 ))Optical intensity

High(3) Loss at optical splitter(15 dB)

Attenuation loss 18 dB(( 1 ) + ( 2 ) + ( 3 ))(4) Launch power of OLT(6 dBm)(5) Receive sensitivity of ONU(-20 dBm)

PC: personal computer* Note: Illustrated power budget and loss values are only examples.

Fig. 1. Optical power budget and optical distribution network attenuation.

7 km is required to provide rural coverage. There arethree possible solutions:(1)	Improve the OLT’s transmitter and receiver performances(2)	Improve the ONU’s transmitter and receiver performances(3)	Improve the performances of both OLT and
ONU
If the customers in the extended FTTH area (>7-kmspan) are uniformly distant from the OLT, the first
option is most efficient because the cost of the OLT
enhancement is shared by multiple customers(ONUs). For this reason, we chose to develop a longreach OLT as the first step. A development summaryis shown in Fig. 2. We have increased the OLT’s
power budget by 3 dB by using a high-efficiency
aspheric lens and a high-output-power light-emitting
diode in the transmitter and an improved amplifiercontrol circuit and transimpedance amplifier in thereceiver. As shown in Fig. 3, the existing OLT chassis
can accommodate the new OLT packages alongside
Vol. 9 No. 10 Oct. 2011

the conventional ones. This minimizes the cost of
expanding the FTTH service area. The long-reach
OLT yields an economical GE-PON system with a
32-dB optical power budget and allows FTTH services beyond 7 km from the central office. It was first
deployed in 2010.
5. Development of even-longer-reach
GE-PON system
FTTH service can be provided to the few, but moredistant, customers, by developing long-reach ONUs
(option 2 above). Our long-reach ONU is summarized in Fig. 4. The transmitter uses an aspheric lensin place of the previous spherical lens and a distributed-feedback laser diode. The receiver uses an avalanche photodiode. The ONU complies with IEC(International Electrotechnical Commission) class 1
requirements for eye safety [2], which is mandatoryfor equipment installed in customer premises. These
improvements to the ONU side raise the powerRegular Articles

Lens:
High-efficiency
aspheric lens.

Long-reach OLT

SC
connector

Splitting/branchingfilterOptical fiberLight-emitting diode:High-output-power DFB-LD.

LD
DriverLens

Transmitted data
Amplification
controller

TIA

Received data

Improved amplification controller
and TIA.
DFB: distributed feedback
LD: laser diodeSC connector: a type of optical connector
TIA: transimpedance amplifierFig. 2. Development summary of the long-reach OLT.

Existing OLT chassis canaccommodate both OLT packages.
Conventional OLT
package

Long-reach OLT
package

Long-reach ONU

SC
connector

Lens:
Aspheric lensLight-emitting device:
DFB-LD

Splitting/branchingfilterOptical fiber

LD
DriverLens

Transmitted data
Amplification
controller

OLT chassis

Controller package

TIA

Received data

Light-receiving device:
Avalanche photodiodeFig. 3. OLT.

Fig. 4. Development summary of the long-reach ONU.

budget by 5 dB.
The new ONU matches the volume and power consumption of the conventional ONU. Since the OLT
can accommodate both long-reach and conventional
ONUs simultaneously, no special techniques areneeded to install the new ONUs in the same PON
network except for regular checks of the optical pathattenuation. The combination of the long-reach OLT
and the long-reach ONU provide an optical powerbudget of 37 dB, which is one of the highest budgetsof any commercial GE-PON system in the world.
NTT has started using this system to deploy FTTH
services to customers more than 20 km from the central office (using a splitting ratio of 1:32).



6. Applications of long-reach GE-PON systems
The long-reach GE-PON system has three main
application scenarios, as shown in Fig. 5: (1) expanding existing FTTH service areas, (2) adding new
NTT Technical Review

Regular Articles

Basic area
Optical loss budget: up to 29 dB
Equipment: conventional OLT & ONUs

Central office A
NormalONU

Long-reach package
Long-reach package
Normal package(1) Expanding existing FTTH service area
Optical loss budget: 29−32 dB
Equipment: long-reach OLT & conventional ONUs

OLT chassis

A

NormalONU
NormalONU

NormalONU
NormalONULongreach
ONU
Longreach
ONU

Normal
ONU

rea

ce a

vi
Ser

A

o

fice

al of

rea

ice a

(2) Adding new FTTH service areas for distant customers
Optical loss budget: 32−37 dB
Equipment: long-reach OLT & long-reach ONUs

ffice

al o

ntr
f ce

Serv

ntr
of ce

B

Central office B

Longreach
ONU

Longreach
ONU(3) Providing FTTH services from a neighboring central office
Optical loss budget: 32−37 dB
Equipment: long-reach OLT & long-reach ONUs

Fig. 5. Application scenarios of long-reach GE-PON.

FTTH service areas for distant customers, and (3)providing FTTH services from a neighboring central
office.
By installing a long-reach OLT package in an existing OLT chassis, we can provide FTTH services tolocations more than 7 km from the central office atminimum cost. For customers living in even further
areas, we can deploy long-reach ONUs, but thehigher installation cost imposes a limit because thelong-reach ONUs will be deployed only to those customers rather than being shared among multiple customers. Although the basic concept of FTTH deployment is to connect ONUs to the nearest central office,some rural central offices do not have any fiber transmission systems. In such cases, it is possible to connect the ONUs to a more-distant neighboring central
office that has OLTs and fiber transmission systems.
Vol. 9 No. 10 Oct. 2011

The 37-dB power budget GE-PON system readily
supports this kind of deployment.
7. Conclusion
We have developed a long-reach GE-PON system(with a splitting ratio of 1:32) that significantly
expands the optical power budget from 29 dB toeither 32 dB or 37 dB. These developments enable us
to expand FTTH service areas cost-effectively. We
have been supporting the commercial deployment ofthese systems and are thus contributing to further
expansion of FTTH service areas in Japan.

Regular Articles

References[1][2]

IEEE Std 802.3ah, 2004.
IEC 60825-1 Edition 2.0, 2007.

Hiroshi Kimura

Shoichiro Yamashita

Research Engineer, First Promotion Project,
NTT Access Network Service Systems Laboratories.
Since joining NTT in 2007, he has been
engaged in the design and maintenance of accessnetworks at the Okinawa branch. He is currently
studying long-reach GE-PON systems and FTTH
network enhancement.

Research Engineer, First Promotion Project,
NTT Access Network Service Systems Laboratories.
Since joining NTT in 2004, he has been
engaged in creating new FTTH services, e.g.,
FLET’S HIKARI Mytown and FLET’S TEREBI. He is currently studying FTTH network
enhancements, especially innovative ONUs.

Takuro Matsumoto

Jin Yamasaki

Research Engineer, First Promotion Project,
NTT Access Network Service Systems Laboratories.
Since joining NTT in 2005, he has been
engaged in access network maintenance. He iscurrently studying FTTH network enhancement.

Research Engineer, First Promotion Project,
NTT Access Network Service Systems Laboratories.
Since joining NTT in 2005, he has been promoting the interconnection of Japanese telecommunication networks. He is currently studying
FTTH network enhancements, especially operation support systems.

Satoshi Shimazu

Research Engineer, First Promotion Project,
NTT Access Network Service Systems Laboratories.
Since joining NTT in 2008, he has been studying FTTH and traffic monitoring systems for
FTTH. He is currently studying long-reach GEPON systems and power saving technologies for
optical access networks.



NTT Technical Review

Global Standardization Activities

Trends of International
Standardization ofThree-dimensional Video Coding
Hideaki Kimata†Abstract

This article introduces the trends of international standardization of three-dimensional video, whichshould lead to new services that differ from conventional television.

1. Introduction
Video compression technologies have made possible various exciting new services since their international standardization started. While the main target
has been high compression efficiency, a lot of attention has recently been paid to three-dimensional (3D)video. International standardization of 3D video has
started and it is expected to lead to novel video services. This article introduces the trends of 3D video
format and compression standardization, which havebeen studied in the Motion Picture Experts Group(MPEG), and mentions the background, applications,and features of the H.264 Annex H (MVC) standard,
which has been adopted in the fixed-media Blu-ray
3D format (MVC: Multiview Video Coding).
2. 3D video and multiview video
We live in a 3D space. Therefore, if we could transmit the 3D space itself, that would be a straightforward way to communicate correctly what one sees as
the scenery and appearance of objects to other people.
However, it is currently impossible to capture the 3D
space itself. Instead, a two-dimensional (2D) image
projected from the 3D space is captured by a camera
and transmitted. Using several camera images captured by multiple cameras enables a large amount ofdetailed spatial information to be communicated. A† NTT Cyber Space Laboratories
Yokosuka-shi, 239-0847 Japancollection of multiple videos capturing the same
scene from different viewpoints is called multiview
video. 3D video is a more general medium for representing 3D space and it may include 3D geometry
information of the scene as well as multiview video.
By transmitting 3D video, we can communicate amore realistic impression of the scenery and appearance of objects than conventional TV can.
3. 3D video and H.264 standardization
3D video representation and compression formats
have been standardized to achieve 3D video services.
3D video standardization activities started about ten
years ago. This was the time when TV services began
to change from analog broadcasting to digital broadcasting, and also it was when personal video delivery
services such as video on demand started. Against
this background, high-compression-efficiency videocoding H.264/MPEG-4 AVC (advanced video coding) standardization by the joint team of ITU-T and
ISO/IEC JTC1 was started in 2001 (ITU-T: International Telecommunication Union, Telecommunication Standardization Sector, ISO: International Organization for Standardization, IEC: International
Electrotechnical Commission, JTC1: Joint TechnicalCommittee 1). On the other hand, expansion of services using new video formats was expected at thesame time (Fig. 1). Since it was predicted that highdefinition television (HDTV) displays would be
popularized within a few years, such new video formats needed to handle different representations fromNTT Technical Review

Global Standardization Activities

Compression efficiency(H.264)

Representation capability(3D video)Interactive
contents

Broadcasts
3D movies

PackagedVideoconferences
media

Fig. 1. Expansion of services resulting from video coding standards.

Navigation

3D movies
Cultural asset
archives(a) Parallel(b) Convergent(c) Divergent

Fig. 2. Camera arrangements and applications.

ordinary TV and Internet video delivery services.
Moreover, a new video format that would treat 3D
space was expected. The standardization of video
representation and compression formats for 3D space
was started in 2001 by MPEG, which is a Working
Group under ISO/IEC JTC1. The MPEG 3D space
activity is called 3D video standardization.
In 3D video standardization, first, video representation formats were classified according to the arrangement of cameras constructing the 3D video. If therelative differences in positions and directions amongcameras are simple, camera arrangements are classified into three types: parallel, convergent, and divergent arrangements (Fig. 2). Applications of 3D video
are also classified according to the camera arrangement.
The parallel arrangement provides enhanced depth
Vol. 9 No. 10 Oct. 2011

impression, as typified by the current boom in 3Dmovies. The convergent arrangement is suitable forfree viewing around a tangible or intangible cultural
asset. The divergent arrangement is suitable for freeviewing of city scenery from the street, as typified by
the current boom in web maps and navigation services.
At about the same time, the depth camera, which
captures depth (distance) information in 2D arrays,
appeared. A depth camera can be used alongside anormal video camera to simultaneously acquire depth
and video (color) information (Fig. 3). Alternatively,
depth information can be estimated by computer
vision technologies from multiple cameras images.
And from the depth and video (color) information, avirtual camera image representing the image thatwould have been taken by a camera having a slightlyGlobal Standardization Activities

Video (color)

DepthFig. 3. Video (color) and depth information.

Table 1. Characteristics of MVC profiles.
ProfileMultiview High Profile Stereo High Profile

Maximum views

1024

2

Interlace scan

Not supported

Supporteddifferent position or angle from the original cameras,
can be synthesized by computer graphics (CG) technologies. MPEG also discussed a 3D video data format supporting image synthesis from depth information. For instance, depth information can be treated asa gray-scale image because it is obtained in a 2D
array. The assumed application was 3D TV.
Because applications were classified according tocamera arrangement and camera type, experiments
exploring the efficiency of data formats were conducted in case studies with end users for 3D video
standardization discussions. From the deep discussion based on the evaluation results, it was concluded
that the fundamental data format for 3D video wasmultiview video, geometry information about thevideos, and depth information according to the conditions. Standardization of Multiview Video Coding(MVC) as a compression format of multiview video
started in 2005.
When MVC standardization was about to start, thestandardization of the state-of-the-art high-efficiency
video compression format H.264 had just finishedand MVC was expected to be standardized over
H.264. Sure enough, MVC standardization started as
an extension of H.264 and it was finished in 2009 andspecified as H.264 Annex H. In H.264, the operational guidelines are specified as profiles, and MVC
specifies two profiles. The main characteristics of
MVC profiles are given in Table 1. Historically, theMultiview High Profile was specified first and theStereo High Profile was specified a couple of years
later.
4. Characteristics of MVC standard
Here, the main characteristics of the MVC standard
are introduced. The main video format is multiview
video, and several functional extensions wererequired to support the assumed 3D video applications. The main features discussed in MVC standardization are listed in Table 2. In MVC, virtual camera
image synthesis is considered as the final process
before display. The series of processes from capture
to display assumed in MVC is depicted in Fig. 4. On
the subject of video streaming, the case of a feedback
streaming channel from a user was also discussed.
When no feedback streaming channel is available, itis necessary to transmit all video streams; however,when it is available, it is possible to transmit only therequested part of the compressed stream. Accordingly, at the acquisition and encoding side, all information should be compressed and then at the display
side, a user will see part of the total. The idea of transmitting only part of the stream is an extension of
conventional scalable video coding. In scalable videocoding, the stream is composed of multiple layers:
the fundamental layer called the base layer should
always be transmitted and other layers are optionallytransmitted in addition to the base layer. On the other
hand, in MVC, because an arbitrary part of stream
should be extractable and transmittable, a base layer
is not defined as a specific layer. Instead, the novel
unit of a view is introduced. The function of extracting an arbitrary part of the stream is called view scalability in MVC. Note that the use of view was

NTT Technical Review

Global Standardization Activities

Table 2. Main features of MVC standard.
Simultaneous output of multiple views

Application to 3D displays

Predictive coding between views

High compression efficiency

Support for view scalability and extraction ofarbitrary viewSupport for various types of 3D display and improved
transmission efficiency

Inexpensive implementation of extension from videocodec

Low cost because only predictive coding is used between
views

View indication
CaptureCorrection

Encoding

View
synthesis

Decoding

Display

Streaming

Fig. 4. Flow of processes assumed in the MVC standard.

View

Inter-prediction

v0
Inter-view prediction
v1

v2
Time

MVC stream

v0

v1

v2

Unit (images with same timestamp)

Fig. 5. Structure of MVC stream.

intended to distinguish camera images, but in the
MVC standard, it is not limited to camera images. For
instance, a view can be assigned to a region of animage and it can be used to extract part of a huge
image. MVC supports many data formats besides
multiview video as a result of the introduction of thisversatile view concept.
In MVC, multiple views are synchronized andVol. 9 No. 10 Oct. 2011

compressed together. Images with the same timestamp for views are compressed sequentially according to the predetermined ordering of views. At the
decoding side, the decoder just decodes part of thestream and obtains the images with the same timestamp as the target views (Figs. 5 and 6). Thus, synchronization is achieved at the codec level and extraction of the target view stream is easily achieved. AndGlobal Standardization Activities

MVC decoder

MVC stream

View 0streamView 1streamView 0image

DecodeView 1
image

DecodeDisplay
View 2streamView 2
image

DecodeInter-view prediction using decoded
images of other views

Output of multiple views

Fig. 6. Example of MVC decoder component blocks.

to improve compression efficiency, predictive coding
between views can be applied when images having
the same timestamp are compressed. This feature isefficient for compressing 3D video and achieves asignificant reduction in the data rate because thesimilarity among views is high in 3D video.
Moreover, one feature for implementation is thatthe compression process is not very different fromthat in a conventional video compression codec.
Since the only difference is predictive coding between
views, an MVC decoder can easily be constructedfrom a conventional video decoder when images ofviews are decoded sequentially.
5. Standardization of related technologies
Several related technologies have been standardized. For the delivery of video contents, the systemlayer standard MPEG-2 TS (transport stream) has
been extended to support MVC. This extension has
led to not only the transmission of 3D video but also
the adoption of MVC as the fixed-media standard
Blu-ray 3D format.
For 3D video viewing without the need for special
glasses, the delivery of supplementary information
about the view synthesis process should be considered because the positions and directions of displayed
views are usually dependent on the capabilities of thedisplay system. Two types of supplementary information have been standardized. One is the camera
parameter of views. This is a description of the camera’s position and direction. The camera parameter isnecessary in order to assume the position of signals ofviews in the 3D space, which are exploited to synthesize a virtual camera image by the CG method of 3D
warping. The camera parameter description is specified in the MVC standard as supplementary information about the compressed stream. The other supplementary information is the relationship between 3D
scene depth and disparity. This relationship is applied
when the depth information that is compressed in thestream is converted into disparity information for 3D
display. The supplementary information about thisrelationship has been standardized as MPEG-C part3, which is independent of compression standards.
For stereoscopic video, the conventional compression format is currently used in TV broadcasting
instead of the brand-new compression format MVC.
In order to transmit two views, stereoscopic video istransformed into a single side-by-side (SBS) formatted video, and mapping information about the SBS
transformation is necessary for the display side toperform the inverse transformation. This mapping
information has been standardized for H.264, and it isunder consideration for MPEG-2 Video.
6. 3D video applications
Let us return to the topic of 3D video applications.
First, for the parallel camera arrangement, 3D TV isassumed. Stereoscopic video is becoming popular asa result of the recent boom in 3D movies, and the
MVC standard has been adopted as the Blu-ray 3D
format to deliver high-quality stereoscopic video tohomes. In the Blu-ray 3D format, the view scalability
feature of MVC is exploited efficiently. For 3D
NTT Technical Review

Global Standardization Activities

display, both views are extracted and displayed; forordinary display, either one view or the other is
extracted and displayed.
On the other hand, the convergent and divergent
camera arrangements are expected to lead to more
exciting services in the near future. For instance, theconvergent arrangement may be used for free viewpoint video covering the whole of a sports stadium,and the divergent arrangement may be used for panoramic video that gives us a strong feeling of actually
being at the site of an event. My coworkers and I havestudied video processing technologies for a panoramic video service.

being studied. This activity is called FTV (free viewpoint TV) in MPEG. An efficient standard should bespecified in the very near future, in time for the current 3D movie boom.
On the other hand, video compression standardization of High Efficiency Video Coding (HEVC), whichshould be the successor to H.264, is also under way.
Like the relation between 3D video and H.264,
another 3D video standardization linked to HEVC
can be expected in the future.
References[1]

7. Conclusions and future activities
This article introduced the trends of 3D video standardization and the novel video services that may
result from it. In particular, features and applicationsof H.264 Annex H (MVC), which has been adopted
in the fixed-media Blu-ray 3D format, wereexplained.
In MPEG, a new activity concerning the next standard after MVC is now under way. To support glasses-free 3D video more efficiently, a new representation and compression format of video and depth are

[2]
[3]
[4]

A. Smolic, H. Kimata, and A. Vetro, “Development of MPEG Standards for 3D and Free Viewpoint Video,” Proc. of SPIE Optics East,
Three-Dimensional TV, Video, and Display IV, Boston, MA, USA,
Oct. 23–26, 2005.
H. Kimata, “3D Video Formats and Compression for Content Distributions,” Proc. of the 17th International Display Workshops, Fukuoka,
Japan, Dec. 2010.
H. Kimata, M. Isogai, H. Noto, M. Inoue, K. Fukazawa, and N. Matsuura, “Interactive Panorama Video Distribution System,” Proc. of
ITU Telecom World 2011 Symposium, Oct. 2011 (to be published).
H. Kimata, M. Kitahara, K. Kamikura, and Y. Yashima, “Free-viewpoint Video Communication Using Multi-view Video Coding,” NTT
Technical Review, Vol. 2, No. 8, pp. 21–26, Aug. 2004.
https://www.ntt-review.jp/archive/ntttechnical.php?contents=ntr2004
08021.pdf

Hideaki Kimata

Senior Research Engineer, Visual Media Communications Project, NTT Cyber Space Laboratories.
He received the B.E. and M.E. degrees inapplied physics and the Ph.D. degree in electricalengineering from Nagoya University, Aichi, in
1993, 1995, and 2006, respectively. Since joining
NTT in 1995, he has been engaged in R&D ofhigh-efficiency video coding and error-resilient
video coding algorithms and high-reality visualcommunication systems. He acted as an editor of
the ITU-T and ISO/IEC international standard
H.264 Annex H (MVC). He is a member of theInstitute of Electronics, Information and Communication Engineers.

Vol. 9 No. 10 Oct. 2011



Practical Field Information about
Telecommunication Technologies

Case Studies of Failures of BusinessPhones Connected to VoIP Gateway
Abstract

This article introduces case studies of failures of business phones connected to a VoIP (voice over
Internet protocol) gateway developed by NTT EAST. It is the seventh in a bimonthly series on the themeof practical field information about telecommunication technologies. This month’s contribution is fromthe Network Interface Engineering Group, Technical Assistance and Support Center, Maintenance andService Operations Department, Network Business Headquarters.

1. Introduction
In parallel with the spread of broadband services, amigration from traditional subscriber telephone services to IP (Internet protocol) telephony is taking
place. When a customer who has been using traditional subscriber telephone services changes to IP
telephony over existing circuits accommodating business phones, connections to those business phones
are made via a VoIP-GW (voice-over-IP gateway).
Consequently, the troubleshooting of business phones
involves VoIP technologies (e.g., Session Initiation
Protocol (SIP) and Real-time Transport protocol(RTP)) used in IP telephony in addition to existing
analog and ISDN (integrated services digital network) technologies used in subscriber telephone services. This article presents two case studies of failuresthat occurred in existing business phones connected
to a VoIP-GW.
2. Case studies
2.1 Business phone unable to make outgoing/incoming calls(1) Equipment configuration
In this example, the customer was using NTT
EAST’s Hikari Denwa Business Type IP telephonyservice and had six VoIP-GWs connected to existing
business phones. The VoIP-GWs were connected to† NTT EAST
Ota-ku, 144-0053 JapanISDN basic rate interface (BRI) units in the main
business phone unit since the customer had beenusing NTT EAST’s INS-Net 64 service* before the IP
telephony service. The equipment configuration isshown in Fig. 1.
(2) Failure description
The customer reported that outgoing and incoming
calls occasionally could not be made via a certain
VoIP-GW. This problem could be resolved by turning
the VoIP-GW’s power off and then on again or by
unplugging and reinserting the cable connected to the
BRI units.
(3) Inspection details
A maintenance console (personal computer (PC))
was used to collect and analyze the failure log fromthe VoIP-GW in question. An ISDN protocol analyzer
was used to monitor the protocol transfers between
the VoIP-GW and business phone. An oscilloscope
was used to monitor signals in the segment between
the VoIP-GW and the ISDN BRI unit (signals
between wires TA & TB and RA & RB) and to inspect
the noise environment at the time of a failure (e.g., thequality of the commercial power supply and telecommunication lines. VoIP analyzers were used to perform packet capture and analyze captured data in thesegment between the optical network unit (ONU) andthe switching hub and in the segment between theswitching hub and the VoIP-GW (Ethernet sections).
* INS-Net 64: 64-kbit/s ISDN service [1], [2]NTT Technical Review

Practical Field Information about Telecommunication Technologies

Main business-phoneequipment

Ethernet

VolP-GW1

BRI

ISDN BRIunits

To extension telephones

To IP telephony network

VolP-GW2

VolP-GW3
Opticalnetwork unit

Switching hub
VolP-GW4VoIP analyzer
VoIP analyzer

VolP-GW5

VolP-GW6

MaintenanceconsoleISDN protocol
analyzer

Oscilloscope

Fig. 1. Equipment configuration.

(4) Inspection results
The VoIP-GW failure log revealed that a “layer 1
down” event occurred many times on the BRI circuit
between the VoIP-GW and main business-phoneequipment. An excerpt from the log at the time that a
failure occurred is shown in Fig. 2. Protocol monitoring using the ISDN protocol analyzer revealed “INFO
lost” indicating “layer 1 down” in the same time
period as the timestamps of the failures recorded inthe VoIP-GW failure log. Signal monitoring between
the VoIP-GW and main business-phone equipment
revealed signal distortion and signal-suspended statesin the signal waveform of the TA-TB line for transmissions from the main business-phone equipment to
the VoIP-GW (Fig. 3). At this time, no changes in
conduction noise in the commercial power supply or
telecommunication lines were detected. Analysis of
captured packed data revealed no packets or sequences that could be considered abnormal.
(5) Cause of failureThis failure was considered to occur for the following reason. Owing to the distortion and suspended
Vol. 9 No. 10 Oct. 2011

Description
Date/time
No. of times
12/06 17:47:46 Line (1) Layer 1 down: 170 times
12/06 17:47:45 Line (1) Layer 1 up: 170 times
12/06 17:41:42 Update check failure (unable to connect to server)
12/06 17:41:42 Firmware update check (automatic)
12/06 05:24:36 Line (1) Layer 1 down: 32 times
12/06 05:24:35 Line (1) Layer 1 up: 32 times
12/06 05:24:24 Line (1) Layer 1 down

Fig. 2. VoIP-GW failure log at time of failure (excerpt).

state of the signal transmitted from the businessphone (TA-TB line signal), the VoIP-GW could notdetect a frame-synchronization signal in three timeframes, which it interpreted as a frame-synchronization offset; this prompted the transmission of an
INFO2 signal and the disabling of outgoing andincoming calls (Fig. 4).

Practical Field Information about Telecommunication Technologies

Signal distortion

Signal-suspended state

800 mV
6.0 ms

8.7 msTA-TBline voltage 0(AC)−800 mV
800 mV

Magnified viewshown in Fig. 4RA-RBline voltage 0(AC)−800 mV

Fig. 3. Waveform at time of failure.

Pattern of frame-synchronization signal
250 µs
800 mV

F bit

No frame-synchronization
signal recognizedNo frame-synchronization signal
No frame-synchronization signal

TA-TBline voltage 0(AC)−800 mV
800 mV

L bit

Initial 0 bit

Distortion
INF02

RA-RB
line voltage 0(AC)Transmission of INFO2 indicating
frame-synchronization offset−800 mV

Fig. 4. Magnified waveform at time of failure.

(6) Countermeasures and results
The ISDN BRI unit connected to the businessphone was replaced. This restored the line to normal
operation.
(7) Summary
An analysis of the VoIP-GW failure log revealed
that “layer 1 down” events had occurred between the
VoIP-GW and business phone, which enabled thecause of this phenomenon to be inferred. Checking
failure logs of installed equipment is a relatively
simple and important form of troubleshooting.


2.2 F aulty transmission/reception in a fax
machine acting as a business-phone terminal(1) Equipment configuration
In this example, a customer was using NTT EAST’s
Hikari Denwa Business Type IP telephony service.
The business phones were connected to a single VoIPGW via the main business phone equipment. They
were also connected to INS-Net 64 as a backup
circuit. The main business phone equipment contained an ISDN primary rate interface (PRI) unit
connected to the VoIP-GW to accommodate the IP
telephony service; an ISDN BRI unit to connect to
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Practical Field Information about Telecommunication Technologies

To PSTN
network
To PSTN
network

Opticalnetwork unit

INS-Net 64

Private-line
testerFax

Ｉ

PRI

Ethernet

ISDN PRI
unit

VolP-GW

VolP
analyzer
Business-phone
VoIP-GW
maintenance console maintenanceconsoleSingletelephone
unit

ISDN
BRI unit

G3 facsimile
testerAnalog line (for testing)To other extension
telephones

To IP telephony
network

Main business-phoneequipment

Fax fortesting

PSTN: public switched telephone network
Private-line tester

Fig. 5. Equipment configuration.

Example of line
being stretched

Exampleof linebeing omitted

Fig. 6. Fax image received at the time of failure.

INS-Net 64; and a single telephone unit, which connected to a fax machine acting as an extension business-phone terminal. The equipment configuration isshown in Fig. 5.

were occasionally distorted (lines stretched oromitted) and sometimes faxes could not be transmitted or received. An example of a fax image received
at the time of failure is shown in Fig. 6.

(2) Failure description
Images transmitted or received by this fax machine(3) Inspection details
A G3 (third-generation) facsimile tester was used toVol. 9 No. 10 Oct. 2011



Practical Field Information about Telecommunication Technologies

Fax transmit side<
Calling tone

Fax receive side
Called tone detection

CED
>

CNG

<=====NSF====== Non-standard function<=====CSI====== Called subscriber identification<=====DIS======

Digital identification signal(repeated 4 times)

Transmission
subscriber identification
Training check======TSI=====>===Signal control==

Frame anomaly CRC error>
TCF<=====NSF====== Non-standard function<=====CSI======

Called subscriber identification<=====DIS======

Digital identification signal<=====FTT======

Failure to train===Signal control==

Frame anomaly CRC error

Digital command signal ======DCS=====>
Fallback Data signal speed: 12,000 bit/s<=====FTT======

Failure to train===Signal control==

Frame anomaly(multiple occurrences)<=====CFR======

Confirmation to receive

Partial page signal: End of procedure ====PPS-EOP===><=====PPR======

Partial page request===Signal control==

Frame anomaly CRC error

Continue to correct ======CTC=====>
Fallback Data signal speed: 2,400 bit/s

Partial page signal:
End of procedure

Disconnect<=====CTR======

Response to continue to correct===Signal control==

Frame anomaly CRC error====PPS-EOP===><=====PPR======(multiple occurrences)

Partial page request<=====MCF======

Message confirmation======DCN=====>
CRC: cyclic redundancy check

Fig. 7. Fax communication sequence at time of failure.

monitor the fax communication sequence. A privateline tester was used to measure the bit error rate on
the transmission path used for fax communications. A
VoIP analyzer was used to capture packets and analyze captured data between the ONU and VoIP-GW(Ethernet interval). Maintenance consoles (PCs) were

used to check the data settings in the VoIP-GW andbusiness-phone ISDN interfaces.
(4) Inspection results
Monitoring of the fax communication sequence by
the G3 facsimile tester revealed “failure to train”
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Practical Field Information about Telecommunication Technologies

Fax transmit side

Fax receive side
CED
CNG

<
Calling tone><=====NSF======

Non-standard function<=====CSI======

Called subscriber identification<=====DIS======

Digital identification signal

Transmission subscriber identification======TSI=====>

Digital command signal======DCS=====>

Data signal speed: 14,400 bit/s
Training check>

TCF<=====CFR======
SIGNAL ON

Confirmation to receive---Signal on-->Partial page signal: End of procedure ====PPS-EOP===><=====MCF======

Message confirmation

Disconnect ======DCN=====>

Fig. 8. Fax communication sequence during normal operation.

signals, “frame anomaly” signals, and drop-in-transmission-speed sequences not observed during normal
operation. The fax communication sequences at thetime of failure and during normal operation are
shown in Figs. 7 and 8, respectively. Bit-error measurements revealed a bit error rate of about 4–5%
(effective number of bits: 106 in both the uplink anddownlink. An analysis of captured packed data
revealed no packets or sequences that could be considered abnormal. Data settings in the VoIP-GW’s
ISDN interface indicated that the synchronization
clock was set to slave, meaning that the clock was
extracted from other equipment.
(5) Cause of failureThis failure was considered to occur because of amismatch in the setting covering the synchronization
clock between the VoIP-GW and the main businessphone unit, which led to unstable synchronization
between them and degraded the transmission quality
and generated defects in the fax communications.
(6) Countermeasures and results
The VoIP-GW synchronization setting was changed
from slave to master so that the clock would be selfgenerated. This prevented this failure from reoccurring.

path used for fax communications affected the qualityof fax communications. When the failure occurred,
only fax communications, which has strict data-transmission requirements, suffered a drop in quality—no
problems such as choppiness could be perceived invoice calls made using other extension (business)
phones.
3. Conclusion
This article presented case studies of failures that
occurred when the circuits accommodating existing
business phones were migrated from traditional
subscriber telephone services to IP telephony in aconfiguration in which business phones were connected to VoIP-GWs. In these case studies, failuresthat did not occur when using traditional subscriber
telephone services occurred when the equipment configuration changed upon migration to IP telephonyand upon the addition of new equipment. Both IP
technologies and existing analog & ISDN technologies are essential in troubleshooting when VoIP is
used with existing business phones.
References[1][2]

http://www.ntt-east.co.jp/isdn_e/e_page/index.html
http://www.ntt-east.co.jp/isdn_e/e_page/e_page08.html(7) Summary
A bit error rate of about 4–5% on the transmission
Vol. 9 No. 10 Oct. 2011

External Awards
JSIAM Best Author Award
Winners: Daisuke Satoh*1 and Masato Uchida*2*1	 NTT Information Sharing Laboratory Group*2 Kyushu Institute of Technology

Date: Sep. 15, 2011
Organization: The Japan Society for Industrial and Applied Mathe-

matics (JSIAM)
For “Worm Propagation Model via E-mail”.
Published as: D. Satoh and M. Uchida, “Worm Propagation Model
via E-mail,” Bulletin of the Japan Society for Industrial and Applied
Mathematics, Vol. 20, No. 3, pp. 236–241, 2010 (in Japanese).

Papers Published in Technical Journals andConference Proceedings
Hierarchical Auto-tagging: Organizing Q&A Knowledge forEveryoneK. Nishida and K. Fujimura
Proc. of CIKM, the 19th ACM International Conference on Information and Knowledge Management, Vol. 2010, No. 10, pp. 1657–
1660, Toronto, Canada, 2010.
We propose a hierarchical auto-tagging system, TagHats, toimprove users’ knowledge sharing. Our system assigns three different
levels of tags to Q&A documents: category, theme, and keyword.
Multiple category tags can organize a document according to multiple viewpoints, and multiple theme and keyword tags can identify
what the document is about clearly. Moreover, these hierarchical tags
will be helpful in organizing documents to support everyone because
different users have different demands in terms of tag specificity. Our
system consists of a hierarchical classification method for assigningcategory and theme tags, a new keyword extraction method that considers the structure of Q&A documents, and a new method for selecting theme tag candidates from each category. Experiments with
documents at Oshiete! goo demonstrate that our system is able toassign hierarchical tags to documents appropriately and is capable ofoutperforming baseline methods significantly.

Designing Efficient Authenticated Key Exchange Resilient
to Leakage of Ephemeral Private Keys
A. Fujioka and K. Suzuki
CT-RSA 2011, Lecture Notes in Computer Science, 2011, Vol.
6558/2011, pp. 121–141, San Francisco, CA, USA, 2011.
We investigate a sufficient condition for constructing authenticated
key exchange (AKE) protocols which satisfy security in the extended
Canetti-Krawczyk (eCK) model proposed by LaMacchia, Lauter andMityagin. To the best of our knowledge, this is the first approach forproviding secure protocols based on the condition. With this condition, we propose a construction of two-pass AKE protocols, and theresulting two-pass AKE protocols are constructed with a single static
key and a single ephemeral. In addition, the security proof does notrequire the Forking Lemma, which degrades the security of a protocol relative to the security of the underlying problem where it is usedin the security proof. Therefore, these imply that the protocols constructed with the condition have an advantage in efficiency such as
sizes of storage and communication data. The security of the resulting protocols is proved under the gap Diffie-Hellman assumption in
the random oracle model.

Digital Cinema over Optical Network—Status of Super HD
Development
T. Fujii, K. Shirakawa, D. Shirai, Y. Tonomura, and M. Kitamura
Proc. of the Optical Fiber Communication Conference and Exposition (OFC/NFOEC 2011) and the National Fiber Optic Engineers
Conference, Los Angeles, CA, USA.
Digital Cinema is a promising application that utilizes high-speed
optical networks to transfer super-high-definition images. The networks are primarily used for distributing packet data of digital cinema
contents and also used to support new services such as the live
streaming of musicals and sports games to movie theaters. While current transfer services offer high-definition (HD) quality video, live
streaming applications will soon shift to cinema-quality 4K for bothbusiness and movie theaters users. The extra-high-quality 4K enables
a realistic telepresence and will be combined with special tools suchas video editing systems to realize effective remote-collaboration forbusiness workspaces. This paper introduces current research onsuper-high-definition image transmission and its application, especially in digital cinema and relevant application fields.

An Approximately Universal Set Consisting of Two Observables
Y. Takahashi
Proc. of the 6th Conference on Theory of Quantum Computation,
Communication, and Cryptography (TQC 2011), Madrid, Spain.

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Papers Published in Technical Journals and Conference Proceedings

We show that if we are allowed to use two ancillary qubits, a set
consisting of one one-qubit observable and one two-qubit observable
is approximately universal for quantum computation. Using theproof, we also show that if we are allowed to use two initialized ancillary qubits, one two-qubit observable is sufficient for graph state
preparation. The use of only one two-qubit observable is optimal interms of the number of observables available and the number of
qubits to be measured jointly.

Generation of a Vocal-tract MRI Movie Based on Sparse
Sampling
S. Hiroya and T. Kitamura
Proc. of the 9th International Seminar on Speech Production(ISSP’11), pp. 1–8, Montreal, Canada, 2011.
We present a novel technique that can provide a high-quality vocal
tract magnetic resonance imaging (MRI) movie during speech production. The method uses MRI vocal-tract images at the central pointof each phoneme and interpolation functions between adjacent phonemes obtained from electromagnetic articulographic data. It isbased on our finding that articulatory parameters are suitable for asparse representation. Preliminary results showed that the quality ofthe obtained vocal-tract MRI movie is high compared with that of theprevious technique. The method will be useful for constructing alarge database of vocal-tract MRI movies and understanding speech
production mechanisms.

Tweet-topic Classification Using Data Compression
K. Nishida, R. Banno, K. Fujimura, and T. Hoshide
Proc. of the 3rd Forum on Data Engineering and Information Management (DEIM Forum 2011), pp. 1–6, Izu, Shizuoka, Japan (inJapanese).
Twitter, a micro-blogging service, has emerged as a new information infrastructure. In this study, we propose a new method that uses
data compression for classifying topics of tweets (conversational,
short, and real-time messages). Experiments with Japanese tweets
assigned hash tags demonstrate that our method using the Deflatedata compression method, which gzip uses, achieved higher precisionand recall rates than the confidence-weighted linear classification
method, which uses the character n-grams or morphemes of a tweet
text as input features.

Design and Performance of a Sub-nano-ampere Two-stage
Power Management Circuit in 0.35-µm CMOS for Dust-size
Sensor Nodes
M. Ugajin, T. Shimamura, S. Muto, and M. Harada
IEICE Trans. on Electronics, Vol. E94.C, No. 7, pp. 1206–1211,
2011.
The design and performance of a sub-nanoampere two-stage
power management circuit that uses off-chip capacitors for energy
accumulation are presented. Focusing on the leakage current and thetransition time of the power switch transistor, we estimated the minimum current for accumulation. On the basis of the results, we deviseda two-stage power management architecture for sub-nanoampere
operation. The simulation and experimental results for the power
management circuit reveal the accumulation operation with a 1-nA
current source.

Vol. 9 No. 10 Oct. 2011

Electrical Characterization of Terphenyl-based Molecular
Devices
T. Goto, H. Inokawa, Y. Ono, A. Fujiwara, and K. Torimitsu
Japanese Journal of Applied Physics, Vol. 50, No. 7, pp. 071603–
071603-6, 2011.
The electrical characteristics of phenylene-based moleculardevices were assessed. A device consisted of nanogap electrodes andphenylene-based conjugated molecules. Two different types ofnanogap electrode were tested. One was obtained by electromigrationof a Au nanowire modified with a self-assembled monolayer (SAM)of 4,4-p-terphenyldithiol and the other was fabricated by the shadow
evaporation of metals and subsequent deposition of a SAM. Some ofthe devices with electrodes of the first type exhibited activationenergy for electrical conduction of up to 0.26 eV. This high activationenergy coincides with the intramolecular barrier estimated by abinitio molecular orbital calculations. On the other hand, all of thedevices with electrodes of the second type exhibited a comparatively
low activation energy. Neither device type showed a clear gate effectwith an electrical field of up to 3 MV/cm. These results indicate thatthe electrical characteristics of molecular devices are affected by the
fabrication process and the resultant molecule-electrode configuration.

Localized Corrosion of Lead in Water Containing High
Concentration of Chloride Ions
M. Watanabe, E. Yoneta, S. Yanagi, M. Matsumoto, M. Kama, H.
Saito, T. Handa, and T. Sawada
Journal of Material Testing Research Association of Japan, Vol. 56,
No. 3, pp. 139–146, 2011.
We investigated the reproduction of crevice corrosion in lead andobserved the corroded samples. Electrochemical tests revealed thepitting corrosion mechanism of passive film on lead surface. The
crevice corrosion progressed with exposure time. First, a passive film
was formed after exposure to the atmosphere. Next, pit corrosion
occurred at the film/metal interface. Roughly speaking, the pit corrosion rate was reduced because of the formation of a new passive film.
However, the corrosion rate of lead was accelerated when the pH
became lower at the crevice.

A System for Creating the Content for a Multi-sensory
Theater
K. Hirota, S. Ebisawa, T. Amemiya, and Y. Ikei
Virtual and Mixed Reality––Systems and Applications, Lecture
Notes in Computer Science, 2011, Vol. 6774, pp. 151–157, 2011.
This paper reports on the current progress of a project to develop amulti-sensory theater. The project targets not only the development of
hardware devices for multi-sensory presentations but also an investigation into the framework and method of expression for creating thecontent. Olfactory, wind, and pneumatic devices that present thesensation of odor, wind, and gusts, respectively, were developed andintegrated into an audio-visual theater environment. All the devices,
including the video device, are controlled through a MIDI interface.
A framework for creating multi-sensory content by programming thesequence of device operations was also implemented.

Concave-convex Surface Perception by Visuo-vestibular
Stimuli for Five-senses Theater
T. Amemiya, K. Hirota, and Y. Ikei



Papers Published in Technical Journals and Conference Proceedings

Virtual and Mixed Reality––New Trends, Lecture Notes in
Computer Science, Vol. 6773, pp. 225–233, 2011.
The paper describes a pilot study of perceptual interactions among
visual, vestibular, and tactile stimulations for enhancing the sense ofpresence and naturalness for ultra-realistic sensations. In this study,
we focused on understanding the temporally and spatially optimized
combination of visuo-tactile-vestibular stimuli that create concaveconvex surface sensations. We developed an experimental system topresent synchronized visuo-vestibular stimulation and evaluated theinfluence of various combinations of visual and vestibular stimuli on
the shape perception by body motion. The experimental results motivate us to add a tactile sensation to facilitate ultra-realistic communication by changing the contact area between the human body andmotion chair.

Sparse Source Separation Based on Simultaneous Clustering of Source Locational and Spectral Features
S. Araki, T. Nakatani, and H. Sawada
Acoustical Science and Technology, Vol. 32, No. 4, pp. 161–164,
2011.
This paper proposes blind source separation methods for sparsesources that have an inherent ability to align the permutation of frequency components, and the approach can be applied even if thenumber of sources is unknown. The proposed method simultaneouslyclassifies both the source locational feature (phase difference
between microphones) and the spectral feature (spectral temporalenvelope). In this method, source separation in each frequency bin is
performed by clustering the source locational features while synchro-

nizing the spectral envelop. Thanks to the common amplitude modulation characteristics, this method inherently aligns the permutationof the frequency components.

Carrier-mediated optomechanical coupling in GaAs cantilevers
Phys. Rev. Vol. B 84, p. 014305, 2011.
H. Okamoto, D. Ito, T. Watanabe, K. Onomitsu, H. Sanada, H.
Gotoh, T. Sogawa, and H. Yamaguchi
We have investigated optomechanical coupling in n-GaAs/i-GaAs
bilayer cantilevers induced by optical band-gap excitation. The
strain-assisted optopiezoelectric effect, which is associated with theseparation of electron-hole pairs due to the built-in electric field,
causes a time-delayed backaction force and influences the thermal
vibration of the cantilevers. Vibration of the [110]-oriented cantileveris amplified by this optopiezoelectric backaction, and self-oscillation
is induced for strong excitation. In contrast, for the [1̅ 10]-oriented
cantilever, the optopiezoelectric backaction dampens the vibration
because the direction of the piezoelectric stress is reversed. We haveexperimentally extracted the response time of this optopiezoelectricbackaction, where the delay is on the order of the nonradiative recombination lifetime in GaAs. This optopiezoelectric backaction is
maximized when the laser wavelength matches the optical absorption
edge. This is because the strain-induced change in the optical absorption is maximized at the absorption edge, so a large force gradientresults.

NTT Technical Review