NTT Technical Review

March 2024 Vol. 22 No. 3

View from the TopToshio Kashiwagi, Senior Executive Vice President, Executive Officer (CIO/CDO), NTT
COMWARE

Front-line Researchers
Seishi Takamura, Visiting Senior Distinguished Researcher, NTT Computer and Data Science
Laboratories

Rising ResearchersTatsurou Hiraki, Distinguished Researcher, NTT Device Technology Laboratories; NTT Device
Innovation Center; NTT Nanophotonics Center, NTT Basic Research Laboratories

Feature Articles: Keynote Speeches at NTT R&D FORUM 2023 — IOWN ACCELERATION

Akira Shimada, President and Chief Executive Officer, NTT Corporation

Sachiko Oonishi, Executive Vice President, Head of Research and Development Market
Strategy, NTT Corporation



Shingo Kinoshita, Senior Vice President, Head of Research and Development Planning, NTT
Corporation

Feature Articles: Efforts in the Environmental and Energy Sector to Create a Sustainable andResilient Society

Forefront Initiatives of NTT Space Environment and Energy Laboratories



Zero Environmental Impact Technology to Achieve a Clean and Sustainable SocietyLong-distance Laser-energy Transmission for Space Solar Power Systems and Their
Application on Earth

Forefront Research Initiatives on Environmental Adaptation to Enhance Societal Resilience toEnvironmental Changes

Forecasting Technologies for Environmental and Socioeconomic Cycles for Attaining Inclusive
Sustainability

Regular Articles
Long-distance RDMA-acceleration Frameworks

Global Standardization Activities


Activity Report of TTC Bridging the Standardization Gap Working Group

Information


Report on the NTT R&D FORUM 2023 — IOWN ACCELERATION

External Awards/Papers Published in Technical Journals and Conference Proceedings

View from the Top

Don’t Panic, Don’t Get Angry, andDon’t Let It Happen Again
Toshio Kashiwagi
Senior Executive Vice President, Executive
Officer (CIO/CDO), NTT COMWARE
Abstract

NTT COMWARE supports the systems that make up NTT’s telecommunications infrastructure and systems related to service operations from thesoftware side. As a member of the NTT DOCOMO Group, it is also developing systems that will serve as the foundation for expanding the Group’sbusiness. We interviewed Toshio Kashiwagi, senior executive vice president and executive officer (chief information officer/chief digital officer) of
NTT COMWARE, which is committed to providing new value to society
beyond the social infrastructure of telecommunications, about the company’s strengths as a group of software professionals and his attitude as a top
executive.
Keywords: software, system development, IOWN APN

The quality and reliability of NTT COMWARE
that supports Japan’s social infrastructure—Could you tell us about the strengths of NTT
COMWARE, which supports telecommunications
infrastructure as a group of software professionals?
Since its establishment in 1997, NTT COMWARE
has supported NTT Group’s telecommunications
infrastructure by developing software for networkrelated systems and designing, developing, maintaining, and operating information-management systems
and operational systems for tens of millions of telecommunications service users.
Our great strength is our refined technologicalcapabilities. We have approximately 4100 engineers
who support a series of processes—ranging fromsystem planning to development, infrastructure construction, and operation centered on software technology, over 2600 agile-development engineers who
design and rapidly create innovative services throughNTT Technical Review

Vol. 22 No. 3 Mar. 2024

continuous improvement in processes, and over 3400
data scientists and engineers. We are committed toproviding new value by harnessing these technological capabilities.
To continue to improve our technological capabilities into the future, we emphasize human resources
development. We are improving the practical skills
involved in agile-development technology and nurturing engineers who have knowledge and skills
regarding various data-analysis technologies and thelatest digital technologies such as artificial intelligence (AI) and big data.
With this lineup, we are currently undertaking awide variety of projects, which total about 500 per
year. These projects range from large-scale projects
worth several tens of billions of yen involving morethan 1000 members and spanning several years fromplanning to service launch to agile development projects using the scrum framework to support our customers’ businesses in an agile manner.

1View from the Top—NTT COMWARE has supported telecommunications infrastructure while promoting the advancement of technology. In consideration of this history
and the fact that it is now a member of the NTT
DOCOMO Group, what is your current vision?
In 2022, we celebrated the 25th anniversary of thecompany’s founding and, at the same time, together
with NTT DOCOMO and NTT Communications, westarted anew as a member of the NTT DOCOMOGroup. We also launched new NTT COMWARE
Group through the absorption of DOCOMO Systems
and the acquisition of DOCOMO DATACOM, whichbecame our subsidiary. We took this opportunity torenew the COMWARE Identity and Corporate
Message, which state NTT COMWARE’s purpose,important values, and aspirations.
To create the COMWARE Identity, we have formulated the COMWARE New Declaration and NTT
COMWARE Group Sustainability Policy. The former
sets forth the specific business direction that NTT
COMWARE will take up to 2027, while the latter
defines our stance on sustainability activities that are
inseparable from our business.
In a rapidly changing world, it is becoming increasingly important to solve social issues by achieving
sustainability, which means making society, theeconomy, and the environment sustainable into the
future. As the values of consumers, business, andsociety are changing, companies are shifting fromdigitalization—which focuses on efficiency—to digital transformation (DX)—which focuses on the
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added value that can be created through digitalization, and the elements required for this shift are alsochanging. In light of these changes, we need to constantly create new experiences that suit rapidlychanging user values and enhance the stability andperformance of social infrastructure.
With this requirement in mind, we aim to create arich communication society, which goes beyond theefficiency that has been prioritized in the past, bypromoting DX while pursuing advanced software
capabilities, for example, by integrating them with
cutting-edge technologies. While maintaining thequality and reliability that we have always valued, we
focus on activities from a business perspective so that
we can contribute more than ever to the growth anddevelopment of our partners.
Transforming ourselves in a new eraof innovation—In 2023, generative AI has gained momentum. As aproponent of data and AI utilization, what is yourapproach to generative AI and what is the effect of iton sustainability?
I went to the CES electronics trade show in Las
Vegas in January 2023, where I heard nobody mention generative AI; however, two months later, I
remember being very surprised that it was being
talked about in various media. Companies around theworld have since then investigated how to use generative AI, and I feel that they are finally ready to use it.
2View from the Top

We are also experimenting with how to use generative AI in our development process and operations,and NTT DOCOMO Group is making use of it foreach of its businesses. We have also made progress insharing information on how to publicize the use ofgenerative AI, including use cases, and are beginningto understand ways of using generative AI from acomprehensive viewpoint.
System development is still a “human” job; nevertheless, human system development may not be able
to cope with the society of the future, so we must takethe lead in identifying and determining to what extent
AI can take over from humans. Some of the systems
that we currently operate have been in operation since
before today’s engineers were born. New technologies have emerged, and aging and obsolete hardware
has been replaced; however, the basic concept ofsoftware running on it has not changed much fromwhen it was originally developed, although somefunctions have been added and others have been
modified. At the time that software was developed,
the developers probably did not expect their systems
to last longer than their own lifetimes. Even if such
systems have the appropriate documentation in place,the number of pages may be enormous, and thethoughts of the developers may only be understoodby them and their knowledge cannot be documented.
It is challenging to transfer their thoughts and knowledge to the next generation because the developers
and engineers who created a certain system have

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already retired, and the time is coming when we cannot rely on experts. In other words, the aforementioned “sustainability” is no longer possible if we relyon humans. However, since the functions and tasks
provided by the systems are implemented throughsoftware, the software base will also continue to be
used as long as these functions and tasks continue tobe needed. To overcome of this situation, it will be
important to transfer our assets and knowledge to AI.
Perhaps this situation is what the whole world is facing; we are at the dawn of a new era—a turning point.
—The Innovative Optical and Wireless Network(IOWN) is one of the next-generation technologies.
Could you tell us about the technological themes thatNTT COMWARE is focusing on toward the deployment of IOWN?
We are applying our expertise in the development
and construction of operation systems, which has
accumulated over many years of supporting telecommunications services, to achieve the optimal construction and operation of networks and develop
management systems for IOWN. Among the components of IOWN, namely, the All-Photonics Network(APN), Digital Twin Computing (DTC), andCognitive Foundation (CF), we are responsible forthe operations through CF and its information-processing system. We are currently developing systems
related to orchestration, a basic part of CF that3

View from the Top

involves monitoring and automatically operating
various network components and information andcommunication technology (ICT) resources in across-cutting manner.
In 2023, as one of the use cases of IOWN, XR Ping
Pong using the APN was demonstrated for the firsttime at Interop Tokyo 2023. The APN was used toconnect the event site at Makuhari Messe to anothersite in Abiko (both in Chiba Prefecture), which areabout 100 km apart in optical-fiber length to provide
the XR Ping Pong experience. Both players wearing
virtual-reality headsets can feel as if they were playing the game at the same place thanks to the IOWN
APN’s low latency achieving 1/200 that of a normalline.
The APN also makes it possible, for example, tocontrol robots and other equipment installed in a
datacenter in Osaka from the operation center inTokyo as if they were being operated locally inOsaka. This capability has the potential to significantly change the work of development sites, developers, and operators.
For 35 years, I have been unable to sleep in peace—Could you tell us about your background as well as
what you value as a top executive?
After joining NTT in 1988, I started my very first
job—except for the training period—in softwaredevelopment, which is what I am engaged in now.
Even though NTT had been privatized, I believe thelong-distance telephone-call charge at that time wasabout 1000 yen per 10 minutes. A telephone call was
NTT Technical Review

Vol. 22 No. 3 Mar. 2024very expensive compared to today, so I thought I
wanted to contribute to making it cheaper somehow,
and to that end, I wanted to reduce costs related to
networks and systems. Around that time, as tasks that
had been performed by people were being replacedwith software, and specialized hardware was replacedwith general-purpose hardware, cost reduction accelerated considerably. Consequently, the telephone-callcharge was reduced to the current level about 15
years after I joined the company. I’m not sure howmuch I was able to contribute to reducing telephonecall charges, but I had achieved what I set out toachieve when I first joined the company. Looking
back now, I feel that only the foundation for ICT tosolve social issues was in place.
Having spent 35 years working at NTT, during
which time I have mostly been involved in systemdevelopment, I now realize the reality that I cannot
sleep in peace. From the time I joined the company
until now, the number of systems that are in operation
has only increased. Moreover, compared to 35 years
ago, systems today have become more pervasive insocial life, and the importance of stable system operation has increased. If a system malfunctions, thedaily lives of many people will be significantly
affected; for example, people will not be able to takethe train or do their shopping. This trend is unstoppable. Since my job involves such systems, I have no
choice but to recognize that I’m in a situation inwhich I cannot sleep in peace when I consider thesocial implications of those systems. Most people
would want to avoid such a stressful situation; on thecontrary, many people have a sense of pride fromwork that carries such heavy responsibilities.
4

View from the Top

No matter how meticulously we prepare to avoid
system failures during the development process, system failures can occur unexpectedly. Some failures
have a probability of occurring about once every
several tens of thousands of years; regardless, nomatter what the situation, once a failure occurs, wewill do our best to quickly resolve it. Since system
failures are often caused by software, after receiving
reports of such failures, we must calmly and logicallyanalyze the failure in question, investigate the causeof the failure, consider countermeasures, and makefinal decisions on these matters. Accordingly, we try
to take the stance “do not panic or get angry” when
we receive reports of a failure. What’s more, since thereport comes from the employee facing the failure, if
their boss gets upset or angry, accurate information
will not be reported, and errors in judgment will
surely follow. When we have finally solved the failure, since the cause of the failure is identified, wethen try to take the stance “don’t let it happen again.”
I don’t remember how I acquired this attitude or
how it came about. It may have started when I
became a section manager or project manager.
Looking back, I recall that my supervisors and others
generally took this stance when dealing with failures.
—Our daily life is supported by your “don’t let it happen again” stance. Finally, do you have a message
for your engineers, researchers, as well as partners
and customers?
I’ve recently been thinking that I have to change theway I work. Ten years ago, from the perspective ofsystems must continue to be operated normally, I
hoped to welcome tomorrow the same as I had today,
but now, I need to welcome tomorrow that will differ
from today.
While system developers strive to provide the highest quality and reliability possible, they cannot afford
to stop the on-site operations of the people who use
the systems that they develop. It is important to thinkcarefully about what kind of work a system is being
used for on-site and what is the most important work
being done there. Therefore, we are changing ourway of thinking and working by focusing more than

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Vol. 22 No. 3 Mar. 2024

ever on the efficiency and convenience of our customers’ operations. It takes time to change attitudes
and way of thinking, but we cannot take too long
because not only the NTT Group as a whole but also
the world is changing. Nevertheless, we would like tochange as quickly as possible while avoiding harmful
effects in various areas.
I hope that our engineers and researchers willapproach their work keeping in mind how the
research and development they are currently engaged
in will help solve social issues and think about how toadjust to the ever-changing society and how to update
their work accordingly. In the past, we had a sense ofa technician’s skill, such as the mindset “I can be successful on my own,” but the sustainability of society
as a whole is no longer possible based on that sense.
I hope that you will pass on your experiences andknowledge to the next generation and use them as thefoundation for creating something new. I have also
tried to eliminate work that relies on my own uniqueabilities, ideas, and knowledge. I was once told by myboss, “Five years from now, a person in the same
position as you should not tackle the same problems,”
and I thought he was right. And our job is to resolveinconsistencies; otherwise, we are just repeatingtasks. Our work is always fraught with inconsistencies, but I want us to strive to eliminate them.
I’ll conclude with a message to our customers andpartners. NTT COMWARE will continue to provide
the level of high quality and reliability as before. Asa member of the DOCOMO Group, we will strive tocontribute to addressing the challenges facing society. We look forward to continuing our partnershipwith you.

Interviewee profile
Career highlights
Toshio Kashiwagi joined NTT in 1988 andbecame a board member of NTT COMWARE in
2016, executive vice president of the company in2020, and assumed his current position in June
2021.

5

Front-line Researchers

Estimating the True Brightness ofEach Pixel by Using Noise in a Video
Image
Seishi Takamura
Visiting Senior Distinguished
Researcher, NTT Computer and Data
Science Laboratories
Abstract

The key to decoding a coded video in such a manner that the
decoded video is as clear as possible is to remove noise containedin the original video, which also improves coding efficiency.
Many researchers studying imaging have investigated this noiseremoval problem; as a result, it is now said that random noise canbe reduced to the limit at which only shot noise, a type of noise
resulting from the random arrival of photons, remains. Althoughnoise is generally an undesirable phenomenon, research that
exploits it to achieve various effects is attracting attention. Seishi Takamura, visiting senior distinguishedresearcher at NTT Computer and Data Science Laboratories, developed a technology that uses fluctuations (noise) in the brightness of light to estimate brightness beyond the upper limit of digital values. We
asked him about this technology and his stance as a researcher: “question everything,” “don’t be content,” “never say no,” and “let it lie.”
Keywords: image/video coding, noise, 3D-point-cloud image, limit-break sensing

To simultaneously achieve two contradictory
goals concerning image/video coding: highreproducibility and improved compression ratio—Could you tell us about the research you are currently conducting?
I am mainly researching three technologies. The
first is “omni-ambient data-organizing technology”
that enables data to be stored and distributed without
being discarded and compressed 100 to 1000 times
more than possible with general technologies while
maintaining higher quality. The second, “real-entity
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Vol. 22 No. 3 Mar. 2024

mining technology,” removes disturbances such as
noise, distortion, out-of-focus, and missing information from captured images, infers the true appearanceof the subject, and encodes the images on the basis ofthat information. I talked about these two technologies in the previous interview (April 2021 issue). The
third technology uses fluctuations (noise) in thebrightness of light to estimate brightness beyond theupper limit of digital values and accurately estimate
the brightness of dark areas. Since April 2022, I haveconcurrently been a member of a university laboratory researching the omni-ambient data-organizing
and real-entity mining technologies with students as
6

Front-line Researchers

Input image(fern, natural image)Our method, 33 bytes
LPIPS=0.7173

JPEG compression, 1580 bytes
LPIPS=0.7209

Fig. 1. Automatic acquisition of rules hidden in natural pattern images and ultra-high compression of those images.

well as at NTT and researching technology for estimating brightness beyond the upper limit of digitalvalues by using fluctuations in the brightness of lightat the university.
Let me talk about my ongoing research at the university on a method for automatic acquisition of rules
hidden in natural pattern images and ultra-high compression of those images. With this method, if a pattern in nature, such as the pattern on a shell, is converted into a mathematical expression and a manuallycreated algorithm (evolutionary computation engine)is used to automatically generate the pattern (Turingmodel), or if an algorithm is automatically createdand used to automatically generate the pattern (fractal
model), a pattern similar to the original pattern can be
reproduced (Fig. 1). For example, when a fractal
model is used to reproduce a photograph of a fern, thelearned perceptual image patch similarity (LPIPS), a
scale close to human perception, shows an accuracyof 0.7173 (1.0 is a perfect match) achieved in 33
bytes. A JPEG* image of the same LPIPS level would
require 1580 bytes, which comparatively indicatesthat the compression by this method is quite high. I
believe that by applying this method, it may be possible to simulate to some extent what is happening
inside living organisms.
As I mentioned in the previous interview, by adding
one frame of image to the original video and compressing it, it is possible to achieve the same level ofvideo quality with a higher compression rate. I also
confirmed that even-higher compression rates can beachieved by using an infrared image for the additional frame.
With Video-based Point Cloud Compression(V-PCC), which is the international standard forthree-dimensional (3D)-point-cloud coding,
3D-point-cloud information is decomposed into 2D
images for compression, and as shown in Fig. 2, theblack areas in the 2D images are unnecessary areas
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Vol. 22 No. 3 Mar. 2024

Fig. 2. Converting a 3D-point-cloud image to 2D images.

that are not used for final display, although they arecompressed and transmitted. Since the unnecessary
areas can be filled in arbitrarily (so-called “padding”), reducing the difference in color, for example,
between a padded area and the adjacent area, makes
it possible to increase compression efficiency. I am
investigating this padding method and aiming to use*

JPEG: Standards for still image coding developed by the Joint
Photographic Experts Group, a working group of International
Organization for Standardization/International ElectrotechnicalCommission (ISO/IEC).

7

Front-line Researchers

it for actual 3D-point-cloud encoding. The effect was
confirmed in all four test point clouds that I tested.
—Could you explain the technology for estimatingbrightness beyond the upper limit of digital values byusing fluctuations in the brightness of light?
An image always contains noise, such as shot noisecaused by random arrival of photons; random noise,such as thermal noise derived from irregular thermal
vibrations of free electrons in a conductor; quantization distortion in the digitization process; and clipping distortion, namely, the top of an output-signal
waveform is distorted because the input signal islarger than the standard. Images contain much (about
three times) more noise than audio, that is, images
have a signal-to-noise ratio (SNR) of around 40 dB,
but audio signals have an SNR of around 120 dB(lower SNR indicates greater noise). Video that contains a large amount of noise is coded as it was at thetime of capture. Therefore, to obtain a “clear” image,it is necessary to remove the noise, and since removing noise improves the efficiency of encoding, noise
removal has been extensively investigated.
Technology that exploits properties of noise has
also been investigated and enabled us, for example, todetect falsified areas in images. One effective use ofsuch noise is what we call “limit-break sensing,”
which makes it possible to infer the “true brightness”
of an image beyond the theoretical limit of the imagedisplay system.
Each pixel in an image captured with a camera isdigitized as a numerical value (pixel value) that
ranges from 0 to 4095 in the case of 12-bit digitization. The highest (brightest) pixel value is 4095, but
if the actual brightness of a pixel exceeds 4095, allpixels would be thought displayed at 4095 (saturation
value). However, since the image contains random
noise, after multiple shots, the pixel value will fall
below 4095 at a rate determined by the actual brightness.
In an experiment to verify our limit-break sensing,
the row of pixels in the green box on a piece of blank
paper in the photo in Fig. 3 was plotted as a graphwith horizontal pixel position on the horizontal axis
and pixel values on the vertical axis, and the profile
shown in the graph was obtained. When the brightness of the piece of the paper was adjusted to cause
partial overexposure (saturated value) and 10,000
images were captured with a separate 12-bit monochrome camera, the average pixel values were plotted
and the profile shown in Fig. 4(a) was obtained. The
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Vol. 22 No. 3 Mar. 2024

Camera forexperiments

Blank paper

Blank
paper

Fig. 3. Experimental scene.

overexposed area is indicated with the red line. By
comparing the profile plotted in Fig. 4(a) with thatplotted in Fig. 3, it can be estimated that the pixel
values of the red-line area would be as shown as thedashed purple line in Fig. 4(a). When the ideal pixel
values (true brightness) without clipping or quantization are plotted on the horizontal axis and the expected values of the actual output pixel values with clipping and quantization are plotted on the vertical axis,
the relationship shown in Fig. 4(b) was obtained as
the purple curve. If the average pixels value near thesaturation value in Fig. 4(a) are applied to recover the
pixel values of true brightness (namely, average pixel
value A is converted to B in line with the purple curvein Fig. 4(b)), the values in the green points encircled
by the ovals in Fig. 4(c), which exceed the maximum
camera output pixel value (4095), are obtained. This
indicates that the pixel values of true brightness canbe estimated. Note that the fully saturated area (thearea in which the pixel value never falls below 4095
in 10,000 shots) cannot be recovered, so the pixel
value is determined as 4300.
—You have received many awards for these achievements in a short period, haven’t you?
I am grateful that I have received or will receive thefollowing 11 awards and have given six invited lectures since May 2022:•	Standardization Achievement Award from Information Processing Society of Japan (IPSJ)/Information Technology Standards Commission of8

Front-line ResearchersA

St

Blank paperraig
slo ht lpe ineof wit
1 h

Dmax

Dmax

(a)

(b)

B
E (Xd )

(c)Fig. 4. Average pixel values of captured image and results of recovering pixel values of true brightness.

Japan (May 2022)•	IPSJ Fellow (June 2022)•	FY2022 Excellent Patent Award (1st Class) fromNTT Corporation (November 2022)•	Best Paper Award at Picture Coding Symposiumof Japan and Image Media Processing Symposium (PCSJ/IMPS) (jointly won by S. Kudo, Y.
Bando, S. Takamura, and M. Kitahara) (December 2022)•	Best Poster Award at PCSJ/IMPS (December
2022)•	IE Award from the Institute of Electronics, Information and Communication Engineers (IEICE)Technical Committee on Image Engineering(jointly won by S. Kudo, Y. Bando, S. Takamura,and M. Kitahara) (December 2022)•	Certificate of Appreciation from IEEE Region
10 (December 2022)•	IE Award from the IEICE Technical Committee
on Image Engineering (March 2023)•	Fellow from Asia-Pacific Artificial Intelligence
Association (AAIA) (July 2023)•	Certificate of Appreciation from Asia-PacificSignal and Information Processing Association(APSIPA) (November 2023)•	Achievement Award from IEICE (jointly won by
S. Matsuo, Y. Bando, and S. Takamura) (June2024, to be awarded)
Researchers usually receive awards after several
years of research, so ten awards within a year and ahalf of changing my job seems like a lot to me, so mytiming must have been good. However, among thoseawards, the PCSJ/IMPS Best Poster Award in
December 2022 and the IE Award in March 2023
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Vol. 22 No. 3 Mar. 2024

were awarded for research I started after April 2022,
and I am surprised that they were awarded in the firstyear of that research. These two cases are good
examples of how world-first findings can be obtained
without spending a lot of money; for example, theexperiment for estimating true brightness that I mentioned used a camera costing no more than 100,000
yen. Because I did not spend much money, I devised
experimental methods and conducted experimentswith a certain idea of what kind of results I would get,and those experiments turned out exactly as I had
presumed. Therefore, I feel a great sense of accomplishment.
Acquiring research opportunities at universities,
conducting research in a wide range of fields, andcontributing to the increase in the number ofIEEE Fellows from Japan—What kind of research activities will you be focusing on in the future?
I have been researching at a university for a year
and a half now, and I have had two things that I could
not have experienced at NTT laboratories, namely,
obtaining research funds, such as Grants-in-Aid for
Scientific Research and other competitive researchfunds, and giving student guidance, including setting
research themes. As well as applying for researchfunds myself, I also collaborate with researchers outside the university to apply for them. Although it isvery difficult to obtain funding, I finally obtained a
research fund in 2023. The number of students who I
am mentoring has increased from 2 in 2022 to 16 in
9Front-line Researchers

2023, and the weight of research guidance on me has
increased considerably.
At NTT, I have been delving into research themes
within the framework of my laboratory or research
projects; in contrast, at the university, research
themes are not subjected to such a framework, so I
can freely set my themes. However, funds are scarce,
so in addition to continuing the research I have been
doing, I want to gain knowledge of things that no one
else has done in a wide range of fields through experimenting (i.e., desktop theoretical research andthought experiments) while spending as little moneyas possible. The students I give guidance are not professional researchers like those at NTT laboratories,
but apprentice researchers. The number of such students is increasing, and a good environment for
expanding the scope of their research has been created. I also want to increase joint research with companies.
I recently attended the Fellow Committee of theInstitute of Electrical and Electronics Engineers(IEEE), which is a meeting of 50 members selectedfrom IEEE Fellows around the world to make thefinal selection of new IEEE Fellows who will become
Fellows on January 1 of the following year. I was
greatly inspired by the committee members andapplicants who had made outstanding achievements.
IEEE Fellow is a prestigious honor; however, I
noticed recently that the number of Fellows selectedfrom Japan has been significantly decreasing. As I am
fortunate to be one of them, I want to contribute—even to a small extent—to increasing the number ofFellows selected from Japan.
Give it a try, let it lie, and think it from adifferent perspective—Please tell us what you keep in mind as a researcher.
I keep in mind four maxims that form my stance asa researcher: “question everything,” “don’t be content,” “never say no,” and “let it lie.”
Many researchers are aware of the importance ofquestioning everything. Questioning experimental
results and phenomena, rather than accepting them onface value, can lead to the truth or falsehood of theresults, further results, and new discoveries. Questioning is truly an attitude of pursuit.
The “don’t be content” maxim has its origins in myfather’s greeting speech at my wedding reception,
when he said, “My son has done too much (things
have gone too well).” I took his words to mean that I
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had to be careful because I never knew when I might
fail, get sick, or lose my footing. For example, when
you received an award, if you are complacent about
it, you will stop there. The moment you receive anaward, it is a thing of the past. The next step has
already begun. If you follow a predetermined route,
you can only see the road ahead, but if you look aside
a little, you will see a different view.
As I mentioned in the previous interview, “neversay no” means to give without expecting anything in
return. By continuing to give, you will be not only
helped by many people but also able to make important contacts. Since you will be able to understand the
feelings of those who ask you to do something, youwill be able to make a request while considering theother person when you are in the position of the one
who is asking. I have served as a committee member,officer, chairperson, and seminar organizer for several academic societies, and through these activities,
I have come to realize that experience is the bestteacher. I believe that taking on a variety of positions
will lead to one’s growth.
I will give you two examples of “let it lie.” When I
applied for the IEICE 100-Year Memorial Paper
Award Competition, I first gathered a lot of information, continued gathering information without writing
even though I wanted to, and only wrote the paper
after “letting it lie” (leaving it as is and giving ittime), and I received the Best Paper Award. In my
research on uniform color space, I had been trying
and failing to come up with a variety of methods tosolve a problem. While relaxing at the beach on holiday, it suddenly occurred to me to apply a method
used in structural analysis, and by applying thatmethod, I was able to find a way to solve the problem
which led to receiving the Niwa-Takayanagi Award(Best Paper Award) from the Institute of Image Information and Television Engineers. I think both ofthese awards were the result of having a distancefrom the research and being able to look at it fromdifferent perspectives.
—Please give a message to future researchers.
Some researchers carry out research in accordancewith their rigid plans, and other researchers do in amore flexible way, but I think it is good to have bothtypes of researchers. Although I tend more toward theflexible type, I still managed to proceed with myresearch. In other words, since research is often subject to direction changes due to unexpected results, I
think that it has been better to be flexible and repeat
10Front-line Researchers

trial and error. That may seem contradictory to theabove-mentioned “let it lie” maxim, but what I do isgive it a try, let it lie, then change my perspective andthink about it, and sometimes that kind of “give it atry” attitude is necessary. Being young has two
advantages: you have relatively more free time, andyou don’t have to be afraid of losing something since
you don’t have many achievements. I believe thatthese advantages lead to freedom of ideas; therefore,
I think it is good to think freely and give things a try.

NTT Technical Review

Vol. 22 No. 3 Mar. 2024

Interviewee profile
Seishi Takamura received a B.E., M.E., andPh.D. from the Department of Electronic
Engineering, Faculty of Engineering, theUniversity of Tokyo, in 1991, 1993, and 1996.
His current research interests include efficient
video coding and ultrahigh-quality video processing. He has served as associate editor of IEEE
Transactions on Circuits and Systems for Video
Technology (2006–2014), editor-in-chief of theInstitute of Image Information and Television
Engineers (ITE), executive committee member of
the IEEE Region 10 and Japan Council, anddirector-general of ITE affairs. He has also served
as chair of ISO/IEC Joint Technical Committee(JTC) 1/Subcommittee (SC) 29 Japan National
Body, Japan head of delegation of ISO/IEC JTC
1/SC 29, and as an international steering committee member of the Picture Coding Symposium.
From 2005 to 2006, he was a visiting scientist at
Stanford University, CA, USA.
He has received numerous academic awards
including ITE Niwa-Takayanagi Awards (BestPaper in 2002, Achievement in 2017), the IPSJ
Nagao Special Researcher Award in 2006, PCSJ
Frontier Awards in 2004, 2008, 2015, and 2018,
the ITE Fujio Frontier Award in 2014, and theTelecommunications Advancement Foundation(TAF) Telecom System Technology Awards in
2004, 2008, and in 2015 with highest honors, theIEICE 100-Year Memorial Best Paper Award in2017, the Kenjiro Takayanagi Achievement
Award in 2019, Industrial Standardization MeritAward from Ministry of Economy, Trade andIndustry of Japan in 2019 (as an individual) andin 2020 (as NTT team), PCSJ/IMPS Best Paper
Award and Best Poster Award in 2022, Certificate
of Appreciation from IEEE Region 10 in 2022, IE
Award in 2022 and 2023, and Certificate ofAppreciation from APSIPA in 2023.
He is an IEEE Fellow, IEICE Fellow, ITE
Fellow, IPSJ Fellow, AAIA Fellow, and memberof Japan Mensa, the Society for Information
Display, and APSIPA.

11

Rising Researchers

High-performance Optical Devices
with Integration of HeterogeneousMaterials Accelerating the Future of
Photonics-electronics Convergence
Technologies
Tatsurou Hiraki
Distinguished Researcher, NTT Device
Technology Laboratories; NTT Device
Innovation Center; NTT Nanophotonics
Center, NTT Basic ResearchLaboratories
Abstract

The transmission capacity of electrical wiring has come to beviewed as a bottleneck in system processing performance in conjunction with increases in datacenter traffic and the developmentof high-performance large-scale integration (LSI) by transistor
miniaturization. To solve this problem, there is a strong demand for photonics-electronics convergence
technologies for applying optical transmission that can easily increase capacity to wiring positioned
close to electronic circuits. In this article, we talk with NTT Distinguished Researcher Tatsurou Hiraki
to learn about his research and development of “high-performance optical devices with integration ofheterogeneous materials” as a rising researcher opening up a new future.
Keywords: photonics-electronics convergence, integration of heterogeneous materials, optical device

Achieving high-performance optical devices
using the best features of different materials—Dr. Hiraki, please explain “high-performance optical devices with integration of heterogeneous materials” that you are currently researching.
In high-performance optical devices with integraNTT Technical Review

Vol. 22 No. 3 Mar. 2024

tion of heterogeneous materials, I am researching anddeveloping means of drawing out high performanceby combining two or more materials in an optimalarrangement in contrast to past optical devices fabricated with a single-material system. As backgroundto this research, I can point out dramatic increases indatacenter traffic and ongoing improvements inlarge-scale integration (LSI) performance. Because
12Rising Researchers

Transmission by photonics
Processing by electronics

tance

dis
ening

t

Shor

Processing by using photonicselectronics convergence technologies

of o

n

nectio

ercon

l int
ptica

Optical core-to-core transmission
In-chip optical-information processing
LSI

Long-distance
optical transmission

Ultra-low-powerconsumption
optical link

OpticalBoardinterconnection

Ultra-large-capacity
information processing

Optical transmission
within datacenter

Fig. 1. Changes in application areas of photonics-electronics convergence technologies [1].

of these developments, transmission capacity of electrical wiring is becoming a bottleneck in system processing performance, and as a result, increasing thecapacity and reducing the power consumption of
optical wiring at datacenters and in computers is
becoming increasingly important (Fig. 1).
Immediately after entering NTT, I took up theresearch and development of devices for optical communication using silicon. At that time, however, I had
to face the fact that these devices were inherently
limited in performance due to the material propertiesof silicon, something that I was not pleased about.
Then, after several years had passed and worrying
every day about what I should research, a reorganization of NTT laboratories combined the group I was inwith a department working on the integration of compound semiconductor lasers on silicon substrates. At
first, I was a bit confused about the change in research
themes, but thinking that “well, we are all one groupnow,” I actively took up the study of compound semiconductor technology that I had not been very familiar with up to then. As a result, since there were manythings that I had so far given up on due to the material limitations of silicon, I came to think that maybe
I could solve some of those problems by using compound semiconductor materials. But then, focusing
on the fact that both silicon and compound semiconductors have advantages and disadvantages, I alsocame to wonder whether an optical device structurethat combines only the best parts of both types ofmaterials could be used to fabricate various types of
optical devices superior to those of the past without
NTT Technical Review

Vol. 22 No. 3 Mar. 2024

being limited to lasers. This research that I began inthis way is now my current research theme that aims
to achieve high-performance optical devices thatcombine two or more materials.
—What are the issues surrounding conventional optical devices using only a single material?
In the past, optical devices were fabricated separately using silicon, compound semiconductor material, or amorphous material, for example. Each typeof material has its advantages and disadvantages. For
example, indium phosphide (InP)-based compound
semiconductors widely used in the fabrication oflasers feature excellent emission efficiency. Additionally, the advantage of a diode structure having
n-type (negatively charged) and p-type (positively
charged) regions is low electrical resistance, low
optical loss, and high phase modulation efficiency inthe n-type region. The disadvantage here, though, isthat optical loss in the p-type region is extremely
large. As a result, p-type semiconductors havebecome a limiting factor in the structure and performance of lasers and optical modulators. Silicon,
however, which is widely used in the fabrication ofelectronic circuits, features optical loss in p-type
regions less than that of InP-based materials and has
properties conducive to low-cost, mass production.
The emission efficiency of silicon, however, isextremely low, and it is inferior to InP-based materials in terms of electrical resistance, optical loss, andphase modulation efficiency in the n-type region, so
13

Rising Researchers

10000(Gbit/s/mm) / (pJ/bit)

1000

Ele

ctr

ica
l
Parallel bus
High-speed
100bus

TargetResearch field

10
1

On-board bus

0.1

Commercial product

0.01
0.001

0.01

0.1

NTT
(2019) Optical
Transceiver chip

Mid-board optics
100G pluggable transceivers

1
10
100
Distance (m)100010000 100000

Fig. 2. Products and research and development trends related to interconnection [1].

those weak points of silicon material can limit theperformance of optical devices and target applications. Additionally, while many types of materials
exist for configuring optical devices, it is extremely
difficult to find a material system that can satisfy all
requirements by itself, so performance limitations
governed by the properties of each type of material
have been a major hurdle.
Moreover, given that each material has its strong
points and weak points, the general approach today inthe field of optical devices is to first fabricate each
optical component with optimal materials and to thenmount each in a single module. In this type of process, however, integration density is limited by thesize of each component, mounting precision, etc. It istherefore very difficult to use this conventional technique in achieving photonics-electronics convergence that aims to achieve high-density integration of
optical transceivers at positions near electronic circuits (Fig. 2).
With these problems in mind, I have undertaken the
integration of heterogeneous materials—mainlycompound semiconductors and silicon—with the aimof achieving both high performance and high integration in optical devices like optical modulators andsemiconductor lasers by combining the strengths ofboth types of materials.
—Please tell us about some of the achievements you
have already made in this research.
For example, a silicon Mach-Zehnder modulator
fabricated by conventional silicon-photonics technology suffered from performance limitations due to a
NTT Technical Review

Vol. 22 No. 3 Mar. 2024

tradeoff between modulation efficiency and opticalloss. In my research, I overcame this performance
limitation by combining low-loss p-type silicon andhigh-efficiency n-type InP-based material andachieved approximately four times or greater modulation efficiency (0.09 Vcm) with low optical loss
compared with conventional technology. Additionally, by fabricating a laser that combines a membrane
InP-based laser structure and a compact and low-loss
Si optical waveguide, I reduced the optical loss
caused by p-type InP-based material and achieved acompact wavelength-tunable laser. Recently, moreover, by developing an electro-absorption modulator(EAM) that can be integrated together with such amembrane laser on a low-loss Si waveguide, I succeeded in integrating an O-band EAM and opticalsource, which had been difficult to achieve by silicon
optical circuits, and demonstrated 100 Gbit/s highspeed modulation operation (Fig. 3). These researchachievements combine the respective strong points ofsilicon and compound semiconductor materials
thereby drawing out a level of performance beyond
conventional levels. They can be viewed as examples
of successfully achieving high-density integration
using compact Si optical circuits.
Furthermore, to integrate a high-performance
wavelength filter with such a laser or optical modulator, I am working on technology for fabricating a silicon-nitride (SiN) waveguide having optical propagation loss about one order of magnitude smaller thanthat of conventional optical waveguides using silicon. This technology opens up the possibility of fabricating low-loss waveguides in a low-temperatureprocess that inflicts no thermal damage on compound
14

Rising Researchers

Si optical filter

InP-based gain region

High-performance III-V/Si Mach-Zehnder
modulator

Wavelength-tunable, narrow-line-width
III-V/Si laser

n-type InP-based materials having high opticalmodulation efficiency×
Low-loss p-type Si

InP-based material for light source
×Compact and low-loss Si optical waveguide

III-V/Si laser

300 µm

Si waveguideInP-based
modulator

100 µm

100-Gbaud-class EADFB laser
III-V/Si distributed feedback (DFB) laser and high-speed
InP-based electro-absorption modulator (EAM) integrated
on a Si circuit

Fig. 3. Research achievements to date.

semiconductors.
—What hardships have you had to face in yourresearch?
Looking at my research up to now, perhaps there
are some people who would think, “It makes sensethat combining materials with different features
would improve performance.” It certainly would begreat if combining materials could immediately
improve performance, but in actuality, attempting to
do so often ends in failure. The true difficulty lies in“fabrication technology” that aims to achieve integration without losing the good features of each of thematerials being used. For example, the technology
required for fine processing differs between the two
types of materials of silicon and compound semiconductors, and how to fabricate a device without negatively affecting the material properties of both is amajor research issue. Even if the performance thatcan be drawn out by combining materials can beunderstood theoretically by calculations, there aremany problems that must be faced at the fabrication
stage, and if working with new materials or structures, there is nothing but failure at first. The researchof such fabrication technology is a trial-and-error
NTT Technical Review

Vol. 22 No. 3 Mar. 2024

process from one day to the next, and most of that
research period is kept private and hardly talked
about in research papers or elsewhere. Indeed, it may
take several years until a paper can be presented, andin this sense, research can be mentally challenging.
Believing in your research with all your heart isimportant to prevent yourself from becoming totally
depressed during research, but it is also true thatsometimes the direction of your research must bechanged along the way. In actuality, there are manyfatal problems that come to light when starting a fabrication project, and it may be necessary to remain
calm and decide “staying on this course any longer is
not going to work!” It is important that you do notcling to any one matter and that you retreat as needed.
In addition, I believe that it is important within sucha process of failing to actively search out the cause of
failures and to increase the ratio of meaningful failures that can create a path to subsequent research. It
is exactly an increase in meaningful failures that canbe a major turning point in whether you eventually
produce good research results.

15

Rising Researchers

Aiming for core technologies inphotonics-electronics convergence while
exploring new research for the future without
clinging to the past
—Dr. Hiraki, what is your research vision going forward?
At NTT, I belong to three research laboratories:
NTT Nanophotonics Center within NTT Basic
Research Laboratories, NTT Device Technology
Laboratories, and NTT Device Innovation Center.
NTT Basic Research Laboratories is engaged in basic
research covering a wide range of fields from theoretical research to device fabrication technology.
Here, you get the impression that each of its researchers is academically taking on the challenge of newthings. NTT Device Technology Laboratories is
engaged in research that pursues academic novelty
while also being conscious of social needs with aview to practical application in the future. While
themes that reflect the mission of the organization
advance steadily among all the research groups here,
individual researchers also adopt original approaches. Finally, NTT Device Innovation Center is theorganization that, among all the organizations that I
belong to, is the most practical in its orientation. It isinvolved in the commercialization of devices whileworking in cooperation with NTT Group companies
and other companies that actually produce the devices.
In this way, I am involved in research and development spanning a wide range of phases. This kind ofenvironment where a researcher can undertake a wide
variety of technical fields all at once from communication infrastructures to basic research is truly a greatstrength of NTT laboratories. In addition, it is anespecially beneficial environment where I myself asa researcher can grow. Although I knew practically

NTT Technical Review

Vol. 22 No. 3 Mar. 2024

nothing about optical communications and opticaldevices before entering the company, I was able tostart learning from the very beginning thanks to thegracious support I received from many top-classexperts residing at NTT. There were also many times
when I noticed the good points and bad points of myown technology through the discussions I had withresearchers in other fields, so being able to come up
with fresh ideas at any time in this way is likewise agreat strength of NTT.
When taking up a new challenge, I am fortunate inhaving opportunities to receive the cooperation ofexperts having technology that I lack, which gives me
many chances to produce research achievements having a speedy impact or to establish new technologythat might give rise to a paradigm shift. Among thereaders of this article, there might be many whose
current field of specialization differs from theresearch themes at NTT laboratories, but I think thatviewpoints from other fields have the potential of
making great changes to existing research. To any
readers who are looking for an opportunity to change
fields and pursue new research, I would say, “Let’s
work together in accelerating the coming of a new
future in optical communications.”
Reference[1]

T. Sakamoto, N. Sato, and T. Segawa, “Photonics-electronics Convergence Technologies for Disaggregated Computing,” NTT Technical
Review, Vol. 19, No. 7, pp. 58–64, July 2021. https://doi.org/10.53829/
ntr202107fa8

Interviewee profile
Tatsurou Hiraki received his M.E. degree fromTohoku University in 2011 and entered NTT in
the same year. He is a member of NTT Device
Technology Laboratories, NTT Device Innovation
Center, and NTT Nanophotonics Center within
NTT Basic Research Laboratories. He received
his Ph.D. degree in engineering from Tohoku
University in 2017. Since 2022, he has been a
Distinguished Researcher at NTT Device
Technology Laboratories. He is engaged in the
research and development of photonic integrated
circuit technologies using silicon, compound
semiconductors, and amorphous-material opticalwaveguides and optical devices for communications applying those technologies.

16Feature Articles: Keynote Speeches at NTT R&D
FORUM 2023 — IOWN ACCELERATION
Innovating a Sustainable Future for People and Planet
NTT R&D Initiatives
Akira Shimada
President and Chief Executive Officer,
NTT Corporation
Abstract

This article presents the research and development (R&D) activities of
NTT as it continues to innovate a sustainable future for people and theplanet. It is based on the keynote speech given by Akira Shimada, president and chief executive officer of NTT Corporation, at the “NTT R&D
FORUM 2023 ― IOWN ACCELERATION” held from November 14th
to 17th, 2023.
Keywords: IOWN, All-Photonics Network, large language model

1. Major challenges facing society
I would like to point out three of the major challenges facing society today.
The first challenge is the severe labor shortage. In
addition to the decline in workforce, we in Japan are
also facing the so-called “Year 2024 Problem” resulting from the enforcement of new overtime regulations, which has become a major issue in the construction and transportation industries.
The second challenge is the environmental impact
of energy consumption that has become a global
issue. The dramatic increase in data volume has led toa surge in electricity consumption, and energy
demand, especially in urban areas, is growing. We
need to harmonize the addressing of environmental
and energy issues without stopping the progress oftechnological innovation.
The third challenge is that, with the advent of anaging society, rising healthcare costs have become amajor factor contributing to the strain in Japan’s fiscal situation. It is also necessary to create a wellbeing society that enables various people to live ahealthy and fulfilling life.
We aim to address these challenges through NTT’s
research and development (R&D) centered on the
Innovative Optical and Wireless Network (IOWN), a
next-generation communication and computing
NTT Technical Review

Vol. 22 No. 3 Mar. 2024

infrastructure that achieves high capacity, low latency, and low power consumption, and NTT’s large
language model (LLM) “tsuzumi,” a compact andpower-saving large-scale language model withworld-class language-processing capabilities.
2. IOWN
Our ultimate goal for IOWN is to increase power
efficiency by 100 times and transmission capacity by
125 times and to reduce end-to-end delay by 1/200th.
As a roadmap for IOWN, we started the commercial launch of IOWN1.0 at the end of fiscal year (FY)2022 (Fig. 1). I will explain some use cases of
IOWN1.0 later. We plan to develop photonics-electronics convergence (PEC) devices for inter-board
connection by FY2025 as IOWN2.0. Subsequently,
we will develop a device for inter-chip connection as
IOWN3.0 by FY2028 and aim to achieve intra-chipconnectivity with PEC as IOWN4.0 by FY2032.
The important point of IOWN2.0 is to apply PEC
devices to computing (Fig. 2). A high-capacity, lowpower, and compact optical engine is key to achieving this goal. Using this optical engine and a switchboard equipped with the optical engine, the xPU (xprocessing unit) and memory can be connected with
optics instead of electricity to achieve ultra-low power
consumption IOWN computing. IOWN computing
17

Feature Articles

Improving IOWN with photonics-electronics convergence (PEC) devices for All-Photonics Network (APN)
services and servers

IOWN1.0(Optical inter-chip connection)(Optical intra-chip connection)

IOWN4.0

FY2025–

FY2029–After FY2030–

Ultra-low-latency services

Ultra-low-latency, highcapacity, low power
consumption services

Ultra-low-latency, ultra-highcapacity, ultra-low power
consumption services

Further low power
consumption
services

Compact/low-powerdevices for networks

Inter-board
connection devices

Inter-chipconnection devices

Optical Intrachip connection

Ultra-low power
consumption servers

Further low power
consumption
servers

services

PEC
devices

IOWN3.0(Optical inter-board connection)

FY2023–

FY2022APN

IOWN2.0

Servers(SWB)

Low power
consumption servers

SWB: super white box

Fig. 1. Roadmap for IOWN.

Developing a high-capacity, low-power-consumption compact optical engine that will open up new possibilities
in computing
Connecting xPU and memory optically instead of electrically to achieve ultra-low-power computing
In process of conducting tests for commercial implementation with the launch of a switching device equipped with opticalengines scheduled for FY2025
Illustration
ustration of Optical Engine/Switchboard
Under Development

Energyeefficiency
Acce

lerat

Acce

8x

Optic
Engin al
e

or

lerat

100x*

or

Current
ASIC: application-specific integrated circuit
CPU: central processing unit

IOWN2.0

IOWN4.0* Energy efficiency rate across the entire photonics application area, including APN and servers

Fig. 2. IOWN2.0 – Optical-based computing.

can increase power efficiency by up to eight times
compared with conventional computing.
The development of the optical engine is basicallycomplete, and tests are being conducted for its commercial use. In FY2025, we plan to start providing
switchboards equipped with optical engines. We are
NTT Technical Review

Vol. 22 No. 3 Mar. 2024

planning to let you experience such service using
IOWN2.0 at EXPO 2025 Osaka, Kansai, Japan. The
theme of NTT Pavilion is “Architecture with Emotion” (Fig. 3). The “living pavilion” will be represented by “cloth” covering the pavilion that moves
according to the excitement of the visitors and18

Feature Articles

Will showcase IOWN APN as the network for the Expo venue
IOWN computing will create the NTT “Architecture with Emotion” Pavilion
NTT Pavilion“Architecture with Emotion”©Expo 2025

IOWN APN

Expo Venue

IOWN
Computing

IOWN APN

NTT datacenter

Provided by Japan Association for the 2025 World Exposition

Fig. 3. IOWN at Expo 2025 Osaka, Kansai, Japan.

changes expression according to natural light andwind. These are achieved through remote artificial
intelligence (AI) analysis using the All-Photonics
Network (APN) and IOWN computing.
3. NTT’s LLM “tsuzumi”
Next, I would like to introduce NTT’s LLM, “tsuzumi,” the result of over 40 years of research andexpertise on natural-language-processing technology.
This LLM has four key features.
The first key feature is its linguistic capabilities. It
supports Japanese as well as English and a variety ofother languages. We are very proud of its world-classperformance in a variety of Japanese benchmarks.
The second key feature is its high level of cost performance. Demonstrating low power consumption
and high graphics processing unit (GPU) performance while having the same high performance as
OpenAI’s Generative Pre-trained Transformer 3(GPT-3) results in its sustainability.
The third key feature is its low cost of tuning. It iscapable of frequent information updates and customization based on industry- and organization-specificdata.
The fourth key feature is its functionality with various input formats such as diagrams, charts, andtables. It is the first Japanese model that can read
contracts and invoices containing tables.
We compared tsuzumiʼs Japanese language capabilities with LLMs of other companies. It has worldNTT Technical Review

Vol. 22 No. 3 Mar. 2024

class performance in Japanese, which is better than
OpenAIʼs GPT-3.5 and significantly exceeds otherdomestic LLMs of the same class. It even shows English capabilities equivalent to Metaʼs world-class
LLM and is capable of handling other languages.
A comparison of cost performance, a key feature
mentioned earlier, with GPT-3-scale LLMs is shownin Fig. 4. Because it requires fewer GPUs, tsuzumi isable to achieve similar performance as GPT-3-scale
LLMs with 1/25th the hardware costs for training. It
also requires only 1/20th the cost for use. It uses lesspower because it requires fewer GPUs.
LLM tsuzumi will be launched in March 2024. We
began expansive internal and external trials in October 2023 and are already starting to see the results.
Beginning in April 2024, it will not only be able toread documents and graphics but will also be able torecognize voices and tones, such as children’s voices,and will have successive releases in other languages
in addition to Japanese and English.
4. Addressing social challenges using NTT’s
R&D technologies and services
I will now introduce our efforts to address social
challenges using NTT’s R&D technologies and services such as IOWN and tsuzumi.
4.1 Addressing the severe labor shortage
In the construction industry, labor shortages, long
working hours, and the aging of engineers are19

Feature Articles

Achieves high capability while reducing hardware costs necessary for the implementationand operation of generative AI
Main cost components necessary
for generative AI
Operation cost
(Operators, etc.)

Software(the LLM, etc. )Electricalpower

Hardware/Datacenter

AI’s Customizability

Use(Knowledge updates, etc.)

GPU cost
GPU cost
Compared to GPT-3-scale
LLM
Approximately

1/25

Compared to GPT-3-scale
LLM
Approximately

1/20(Based on NTT estimates*1)(Based on NTT estimates*2)*1 Calculated from the parameter ratio
from the same training dataset*2 Calculated from expected costs ofutilized GPU models

Fig. 4. High level of cost performance.

becoming more serious. Since the upper limit on
overtime work will be enforced from 2024 in Japan,
work-style reforms such as operational streamlining
and employment diversification are required. In
response, NTT, in cooperation with EARTHBRAIN,JIZAIE, and Takenaka Corporation, is promoting
remote control of construction equipment for efficient and safe construction. Specifically, by using the
IOWN APN—which has high-capacity, low-latency,
and no lag fluctuations—in remote operations, it will
become possible to operate construction equipment
as if they were being operated onsite.
I will present a case study on remote content andbroadcast production, which we are currently pursuing with Sony. Whenever there had been a match or
event held at a stadium anywhere in the country,
large-scale production spaces, personnel, equipment,
broadcast vehicles, and other production items havealways been needed. By using the APN to connect
broadcast stations to stadiums around the country, it
will become possible to achieve remote content production instead, which would reduce the amount of
space, personnel, equipment, broadcast vehicles, andother production items needed at the time of theevent. On November 13, we entered into an agreement with Sony to collaborate further on this.
I will now present another case study involving collaboration with Tokio Marine & Nichido Fire Insurance. We are aiming to improve the productivity ofcontact centers by using tsuzumi. Tokio Marine &Nichido Fire Insurance has more than 10,000 operaNTT Technical Review

Vol. 22 No. 3 Mar. 2024

tors in the accident-response department nationwide
who provide daily support for non-life insurance.
Operators listen carefully to the circumstances of theaccident and injuries on the phone, and after the call,they organize their responses and input necessary
information into the system. This after-call worktakes about 800,000 hours per year. We have alreadymade small reductions through voice mining, etc., but
by combining tsuzumi with voice mining, we canmake progress in summarizing and organizing thecontent of the correspondence and expect to reduce
the operation of after-call work by more than 50%.
I will talk about autonomous driving systems.
Regarding public transportation, such as local buses
and taxis, the shortage of drivers in the regions has
become apparent. Autonomous driving technology is
expected to address various social issues. NTT has
invested in May Mobility, a U.S.-based company thathas strengths in autonomous driving technology, andhave acquired exclusive rights to sell their autonomous driving solutions in Japan. Through cooperation with several local governments facing transportation issues, we will first provide services throughcommunity buses then expand to many other types ofautonomous vehicles to address various social issues,
including driver shortages.
4.2 A ddressing the environmental impact ofenergy consumption
In a data-driven society, huge amounts of power are
required to process rapidly increasing amounts of20

Feature Articles

In order to promote distributed datacenters, we plan to conduct APN connection tests in the U.S., U.K., and Japan
It will be possible to operate datacenters approx. 100 kilometers apart as if they were a single datacenterIn the future, we will also begin testing in other areas beyond the U.S. and U.K.
[UK]

Hemel – Dagenham[USA]

Ashburn

IOWN APNIOWN APN

100 km

10 km

Hemel Hempstead 4 Data Center

London 1 Data Center

Scheduled to complete test implementationin the U.S. and U.K.
(within FY2023)

Map data ©2023 Google

Fig. 5. Creating distributed datacenters – Implementing the APN between datacenters in overseas markets.

data. For example, the power consumption of datacenters is expected to increase by approximately 6times in Japan and 13 times in the world from 2018 to2030 as the volume of data handled increases. AI willcontinue to grow and expand, but LLMs such as
ChatGPT require as much as 1300 MWh of power for
one training session. This is equal or greater than theamount of electricity generated by operating one
nuclear power plant for one hour. In this data-driven
society, the need for datacenter computing will continue to grow and consume more power than everbefore. NTT is addressing this expanding powerconsumption problem with distributed datacenters
using the APN. I introduce three use cases of how
distributed datacenters can be used.
The first case study is using the APN to connect
datacenters in Japan for use in training LLMs. To
train tsuzumi, we used the APN to build a collaborative cloud and on-premises environment. We have alarge volume of training data at our Yokosuka laboratory, but due to power issues, we found that it wasdifficult to install GPU equipment in that area. We
therefore used the APN to connect the GPU cloud inour datacenter in Mitaka with our training data storage in Yokosuka to conduct the training. Therefore,
we were able to create an environment that was completely comparable with the local environment.
The second case study is in collaboration with
Oracle. We are currently conducting testing to use the
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APN to connect Oracleʼs cloud with NTTʼs datacenters. This will be possible to keep important data at
hand while linking only the data necessary for analysis to the cloud in real time.
The third case study is an example of implementing
the APN between NTT datacenters overseas. To
achieve distributed datacenters, we are advancing
APN-connectivity test preparations between datacenters, not only in Japan but also overseas, initially in
the United Kingdom and United States. In the U.K.
for example, it will be possible to operate a datacenterin London and another approximately 100 kilometers
outside the city through transmission lines as if they
were a single datacenter (Fig. 5). We plan to complete
this testing during FY2023. We also plan to expand
this to other regions of Asia and other areas beyond
the U.S. and the U.K.
4.3 Addressing rising healthcare costs due to an
aging society and the pursuit of a society withgreater well-being
I would like to talk about the challenges in the
medical field. While the introduction of digitalpatient records has been advancing in Japan, patient
record-keeping methods for even the same symptoms, for example, differ among hospitals and doctors, making it extremely difficult to collect and use
patient record data. As tsuzumi is lightweight, flexible, and capable of learning patient data securely, it
21

Feature Articles

can interpret medical data recorded by doctors andarrange them in appropriate expressions and a uniform format to make data more suitable for analysis.
At Kyoto University Hospital, tsuzumi is alreadybeing used to structure the data from digital patient
records. Dr. Manabu Muto from Kyoto University
said, “As digital patient record structuring and analysis advances by utilizing tsuzumi, it becomes possible
to deliver effective personalized medical treatment
for each individual, or what is called precision medicine.” This will lead to the optimization of medical
expenses across society as a whole. With structured
digital patient record data, it will also be easier toanalyze medical data relating to the effects and side
effects of medication. We believe this will lead to theeffective development of pharmaceuticals by reducing development time and costs.
Finally, I introduce our efforts to achieve a wellbeing society. DJ MASA, or Mr. Masatane Muto, is aformer employee of the advertising firm Hakuhodo
and has been active in music as a DJ. In 2014, at theage of 27, he was diagnosed with amyotrophic lateralsclerosis (ALS), an incurable disease in which the
motor nerves that enable the body to move begin to
break down, leading to gradual loss of movement.
One can hear but is unable to respond. His firstthought was, “Is this it, is my life over, why me?”Then he thought, “Even if my body is disabled, there
has to be a way that I can express myself with technology.” He now participates in many events as a DJ

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by playing music with gaze-control. NTT wanted tocollaborate with him, so we asked, “What would you
like to do if you could move your body?” To which heresponded, “I would like to party with the audience.”
To make this a reality, we combined the virtual andreal worlds to enable him to engage the audience
using an avatar. At the Ars Electronica Festival, aworld-renowned media art festival, DJ MASA communicated with the audience in English using his
voice and performed live through an avatar. The audience responded enthusiastically when the avatar’s
hands were raised by him; thus, the performance wasa great success.
NTT is researching and developing technologies
that will give people with even serious disabilities,
such as ALS, the ability to communicate. For people
with serious disabilities, physical expressions can bedifficult, but by using motor-skill-transfer technologythat can respond to even small amounts of muscle
movements and brainwaves, an avatar can be used to
produce physical expressions. For people who havelost their ability to speak, we are working on crosslingual speech-synthesis technology that can synthesize the voice they lost and make it possible for themto not only converse with their voice in Japanese but
also in English and other languages.
Going forward, NTT will continue to take on challenges to innovate a sustainable future for people andthe planet.

22

Feature Articles: Keynote Speeches at NTT R&D
FORUM 2023 — IOWN ACCELERATIONIOWN ACCELERATION―Imagination and Creation―
Sachiko Oonishi
Executive Vice President, Head of
Research and Development Market
Strategy, NTT Corporation
Abstract

This article introduces NTT research and development (R&D) efforts
from two perspectives: the “product-out” approach and the “market-in”
approach. It is based on the keynote speech given by Sachiko Oonishi,
executive vice president, head of Research and Development Market
Strategy of NTT Corporation, at the “NTT R&D FORUM 2023 ― IOWNACCELERATION” held from November 14th to 17th, 2023.
Keywords: IOWN, R&D, food, health, humanity

1. Introduction

2. NTT’s R&D from the product-out perspective

The Research and Development Market Strategy
Division in NTT Corporation was inaugurated inJune 2023. Our mission is to create new value by fusing our traditional “product-out” research and development (R&D) approach with marketing. This article
introduces our R&D work from two perspectives: theproduct-out approach and the “market-in” approach.
The Innovative Optical and Wireless Network(IOWN) has grown out of exploring and exploiting
technologies that connect people, which originatedfrom the telephone. It is the result of the product-out
approach to R&D. There is also the market-in
approach, in which we create a vision of people, society, and the planet and of how we can create a futurethat is sustainable yet also exciting to live in thenpush forward the kind of R&D we need to make thisvision a reality.
A technology truly takes its first breath when it is
implemented as part of society. Four years since theannouncement of IOWN, I hope that you can now
feel this idea coming to life and can create in yourminds a mental picture of the exciting future that will
ultimately make it possible.

2.1 T
 he starting point of technologies that connect people
Figure 1 shows the very first telephone (in Japan)
back in 1890, 133 years ago. This is the starting pointof technologies that “connect people.” When you
telephoned someone in those days, how long did ittake before you could actually start talking? You
couldn’t dial these early phones; after lifting thereceiver, you had to connect to an operator. It worked
as follows: in the morning, say, you’d tell the operator“Can I speak to Ms. A, please?” and in the evening, 6hours and 7 minutes later, you’d finally get to talk to
Ms. A. You could also pay double the fee for an“urgent” connection, which took only 2 hours and 26
minutes.
Following this first phase of telephone development, the Electrical Communication Laboratory
under the Ministry of Communications was inaugurated 75 years ago. In 1966, our research into opticaltechnology and optical fibers began. These technologies that connected people have ultimately made it
possible to connect people and information, people
and objects, and the real and virtual domains, and to

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Directory ofsubscribers

December 16,
1890

No. of subscribers: 197 households (Tokyo/Yokohama)Monthly fee: 40 yen(Equivalent to 150,000 yen in today’s money)

Fig. 1. The very first telephone in Japan.

(Power consumption in mW)
Electrical wiring

Electrical wiring
Electrical wiring

Optical wiring

Optical wiring

Optical wiring(Circuit board transmission distance (cm))
Source: NEDO, Material of International Symposium on Photonics and Electronics Convergence (2015.6.16).

Fig. 2. Difference between electrical and optical technologies.

transmit not just sounds but images, data, skills,
experience, and spaces.
Our 50 years of research into optical technology
have now culminated in the concept of IOWN. This
concept is about using light not just for conveying
information but also in processing layers. Let us lookat the differences between electronics and optical technology. As Fig. 2 shows, with electronics, power
consumption increases dramatically as transmission
distance over circuits grows [1]. Moreover, as proNTT Technical Review

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cessing speeds increase, higher operating frequencies
are also required, further increasing power consumption. However, with optical technology, even as thetransmission distance grows longer and operating
frequency increases, power consumption does notincrease. This feature means power consumption canbe reduced further by using optical technology notjust for transmitting information but also in theinformation-processing layer.
By bringing optical technology into all layers from24

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the network to data-terminal processing, IOWN not
only lets us reduce power consumption but also
improve transmission capacity, quality, and latency.
For example, the All-Photonics Network (APN) features optical technology end-to-end without the traditional switching between electronic and optical technologies, enabling latency-free speed and streamlined power usage. Let us use transport as an analogy.
If you have to change trains several times to get toyour destination, you are certain to arrive later. The
APN works like taking the bullet train all the way toyour destination, with no changes required.
At the Japan World Exposition, Osaka, 1970, thefirst cordless phone was exhibited, connecting peopleby transmitting sound. At this time, fixed landline
phones were still the norm. Following the first-everexhibition of cordless phones, pagers then cordlessphones and smartphones quickly came into widespread use. At the Expo 2025 Osaka, Kansai, Japan,
the IOWN APN will be used to transmit spaces in realtime, by connecting NTT’s datacenter (DC) with the
NTT Pavilion venue. Using artificial intelligence(AI) to analyze the NTT Pavilion at the DC, we
intend to virtually recreate the Pavilion, letting users
experience the dynamically changing and exciting
atmosphere of the real live venue.
2.2 Start of IOWN1.0
From the development of the first telephone, it tookaround 90 years for landline phones to become nearuniversal in Japan. With cars, it took 30 years for the
penetration rate to exceed 80%, shrinking to 15 years
for the Internet, and just 5 years for smartphones [2].
The household-penetration rate for services that havegrown out of technological innovations is increasing
faster and faster.
The growth of IOWN is also gathering speed. Our
IOWN APN1.0 service was launched in March 2023,
four years after the initial vision. As new services
permeate people’s lifestyles at an accelerating rate
due to technological innovation, the power volume
required for this is also growing faster and faster.
Once generative AI is added as well, it is anticipatedthat by 2030 data volumes will have increased 16
times and power consumption 13 times from 2018
levels [3].
With demand for DCs continuing to grow as aresult of this, demand forecasts at DCs already anticipate supply shortages [4]. Power consumption at
DCs in the Netherlands and Singapore now accountfor a large proportion of the total power consumption,
creating a very difficult environment. There are even
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moves to block or limit construction of new DCs[5–8].
The IOWN APN is a way to break through this barrier. By creating distributed networks of DCs linked
through low-latency connections using the APN, we
can operate the networks like a single large DC. We
believe that by creating distributed networks ofsmall/medium DCs in available spaces, putting DCs
in places where there is slack in the power demand or
where local-energy-for-local-consumption is possible, and connecting these DCs using APN technology, we can reduce power shortages at DCs.
Whereas the maximum distance between DCs to
avoid latency was previously limited to 60 km, theAPN allows DCs to be placed up to 100 km apart. In
the UK, verification testing of DCs in London andDagenham (around 100 km away) connected by the
APN is underway. As shown on the left of Fig. 3,
there is a lack of space for establishing DCs within a
60-km range of London due to high land prices; thus,
expanding the range to a 100-km radius should bringin lower land prices, enabling potential sites to befound.
IOWN, which has grown out of the exploration ofconnection technologies and product-out researchoutcomes, uses technological innovation to make thenew digital information society more energy-efficientand sustainable, enabling a 100-fold increase inenergy efficiency and 125-fold increase in transmission capacity.
3. NTT’s R&D from the market-in perspective
I would like to talk about NTT’s R&D from themarket-in perspective. As the communication domain
has grown to include not only sound but images, data,
the sense of touch, and spaces, R&D’s job is to discuss how these concepts can function in our lifestyles, in society, and across the planet, and how
R&D can use these to resolve social challenges andbuild an exciting future. How will these concepts
change our lifestyles regarding a specific sense; thefood, clothing and shelter we use; our health; entertainment; energy; and ultimately humanity itself? I’mgoing to talk about three of these areas below.
3.1 Food
As we are all aware, we face growing risks to thestability of our food supply. Effects on our diet are
already becoming apparent. With prices of processed
foods and condiments increasing by 20% on averageand grocery bills by 150 or 200% in one year, people
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Land prices in London
suburbs
Land prices: 500,000 - 1 million within 60 km radius
Prices fall to under 300,000 if expanding to a 96 km
radiusTrial introduction completed
UK

Hemel – Dagenham
IOWN APN

96 km radius
60 km radius

https://www.findahood.com/articles/property/london-house-price-heat-map/23

100 kmHemel Hempstead 4 Data
Center

Googl Maps

London 1
Data Center(within FY2023)

Fig. 3. Connecting DCs in London and Dagenham (around 100 km away) using the APN.

are now really feeling the pinch [9–12]. As you may
know, Japan’s food self-sufficiency rate is just 38%,
12th among the 13 major economies [13].
Japan’s agricultural workforce has fallen to justover 70% of the number in 2000. The average age has
increased to 68 [14]. Abandoned land has increased
to 420,000 hectares, twice the size of Tokyo and 1.7
times the 1995 figure [15]. Yet in spite of population
decline and challenging land and climate conditions,some countries are boosting their food self-sufficiency through innovation. The Netherlands is an agricultural superpower, yet 20% of its land is below sea
level, and its agricultural land is just 40% that ofJapan. Nevertheless, through widespread deploymentof large-scale protected horticulture enabled throughtechnological innovation, it has become the world’s
second-largest agricultural exporter. Although the
UK’s agricultural workforce has also declined, it hasbrought its food self-sufficiency rate up to 70% by
developing agricultural science.
On the basis of technologies and solutions delivered by our R&D, NTT Group aims to create innovations in the food-value chain including breeding,agricultural production, livestock, fisheries, and distribution to create a stable supply of food. I will talkabout three of these areas today.
3.1.1 Agricultural production and protected horticulture
NTT AgriTechnology has set up Japan’s largest lettuce greenhouse, the size of 1.5 soccer fields, forprotected horticulture. We have succeeded in increasing yields more than 10-fold with half the traditional
workforce. The expertise we have demonstrated has
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brought in inquiries from inside and outside Japan.
The right photo in Fig. 4 shows a farm we designed
and constructed on contract after inquiries from acustomer. This capsicum farm is the size of three soccer fields. The customer tells us that yields haveincreased four-fold with half the traditional labor. We
are enabling both larger-scale agriculture and reduced
labor needs and combining higher yields with areduced environmental footprint.
We are also providing remote business support
from our automation labs using high-definition video
transmission and robotics, enabling those even withno cultivation experience to get started. By delivering
agricultural support remotely, this system enables asingle expert to provide assistance to several producers.
3.1.2 Produce distribution
With prices undetermined, producers ship all produce to large markets where it is likely to be sold forhigh prices. Such produce is often taken a long way
on all-day truck journeys, rather than going to markets closer to the places it was produced. Produce
gathered together which remains unsold may then be
sent on to another place, or in the last few years may
even be thrown away because of failure to findenough trucks for distribution.
Using IOWN to enable more environmentallyfriendly produce distribution by analyzing and forecasting demand information for produce gathered inmarkets, we hope to ensure that produce will be sent
to consumers in a higher state of freshness and onlyin the necessary amounts, reducing food losses andcarbon dioxide (CO2) emission. In our vision for the26

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Japan’s largest lettuce
greenhouse

Japan’s largest red pepper
greenhouse

Area: Size of 1.5 soccer fields

Area: Size of 3 soccer fields
Contract work for design and construction ofcustomer’s farm based on our own company
knowhow and ICT skills built up on farms

Vegetables (sunny lettuces) grown at the farmare being delivered to cities and local
supermarkets

Farm designed and constructed by NTT
AgriTechnology Corporation

Yamanashi plant

10x increase in outdoor Yield
prediction
cultivation
1/2 of traditional level

4x increase inoutdoor cultivation

Workforce 1/2 of traditional level

Fully-automatedcultivation/environ- Technology
mental control
100% water recycling
Environment
systemGreenhouse/
environmental
controlHeat storage tank

*Requests to conduct tours of facilities are not currently being accepted, due to the needto prevent pests.

Fig. 4. Reduced environmental footprint due to 100% water recycling system.

Impact of ocean acidification
Example: A decline in ocean areas habitable bysea life results in reduced catches of salmon,
and long-term declines in homing rate

Impact of rising CO2 levels on ecosystems

Source: Fisheries Agency, “Summary of inspections
concerning the issue of low catches”

Impact of ocean warming

Decline in phytoplankton and zooplankton
that fish feed upon
Large fish
Small fish

CO2 causes ocean acidification and breaks down
to create hydrogen ions.

Zooplankton
Phytoplankton

Fig. 5. Impact of rising CO2 levels on ecosystems.

near future, we will help people enjoy better-tastingfood with peace of mind by connecting experts withproducers, operators with the actual places where
produce is produced and sold, and producers with
virtual markets, using IOWN to bring consumers
fresh produce they will want to eat and which is betterfor the planet while also improving Japanʼs self-sufficiency rate in food.
3.1.3 Fisheries
Rising levels of CO2 are causing the warming and
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acidification of the oceans [16]. With ocean warming
reducing areas that are habitable by sea life, we areseeing long-term declines in, for example, catches of
salmon, as shown in the graph on the upper right ofFig. 5 [17]. The acidification of the ocean is causing
declines in numbers of the phytoplankton and zooplankton that fish feed upon. In spite of this, the production volumes from fisheries worldwide havedoubled since 2000. While catches of fish haveremained more or less flat, aquaculture has been27

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making up the shortfall. As we can see from the center graph, while global aquaculture production has
doubled, Japanʼs production is actually on the
decline. Therefore, having been ranked No. 1 worldwide for aquaculture in 1980, Japan has now fallen to
No. 11 as of 2021 [18, 19]. In July 2023, NTT Green& Food was established as a joint venture between
NTT and Regional Fish Institute to resolve issues offishing industry decline, food, and the environment.
One aspect that we are working on is qualityimprovement technology for the creation of sustainable foods. One example of sustainable foods is sea
bream with an edible portion that is 1.6 times that ofregular sea bream, while the algae it feeds upon is
given extra-activated photosynthesis, resulting infaster growth, and the ability to fix higher-than-normal levels of CO2 inside its cells.
Another aspect is sustainable land-based aquaculture plants. Atmospheric CO2 is absorbed by theocean, and the modified algae absorb larger-thannormal amounts of it within their cells; the fish eat thealgae, absorbing and fixing this CO2 in their bones
and other parts, creating a sustainable production
mechanism. We are currently constructing Japanʼslargest land-based aquaculture plant in terms of production scale in Iwata (Shizuoka Prefecture), as of
October 2023. The plan for the plant is to produce
whiteleg shrimp as a fully domestic production system using a rare variety of Japanese seedling.
3.2 Health, healthcare, and medical care
Which raises blood sugar levels more: a banana ora cookie? The glycemic index (GI) for food gives
relative values for how high blood sugar rises after
eating certain foods, with glucose given a baseline
value of 100. According to this index, a cookie has ahigher GI value at 77 compared with 58 for a banana.
The correct answer is not straightforward. The correct answer varies from individual to individual.
Among a group of people with pre-diabetes, ‘patients’blood sugar values were measured after they had
consumed bananas or cookies. For 445 patients,
blood sugar rose after eating bananas and remainedlargely unchanged after eating cookies. For 644
patients, however, the exact opposite was the case[20].
We can see from this that changes in blood sugar
are different for different individuals. The number ofpeople with diabetes worldwide has increased 3.6fold over the last 20 years [21]. Rapid rises and fallsin blood-sugar levels increase the risk of cardiovascular disease as well as diabetes. Chronically highNTT Technical Review

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blood sugar damages blood vessels throughout thebody, causing various health issues. Stabilizing blood
sugar after meals is believed to reduce heart diseaseand cancer risks. In other words, blood sugar has amajor impact on bodily health [22].
NTTʼs “wearable blood glucose sensor” is a technology that enables the user to measure their bloodsugar levels at any time, helping them understandwhat foods raise their blood-sugar levels. Blood
glucose has traditionally been measured by drawing
blood or using pinpricks, as shown in the lower left
photo of Fig. 6. The round object attached to the person’s arm contains a needle that is piercing the skinand measuring the blood glucose level. This meansthat continuous, real-time measurement is very difficult. Now, the user can measure their level simply by
wearing NTTʼs wearable blood glucose sensor next
to their skin. The version presented at R&D Forum2022 was quite large, as shown in the central photograph of Fig. 6. However, its size was reduced in
2023 to that of a watch, as shown on the right. The
watch-sized sensor directs electrical waves under theskinʼs surface. These are then bounced back to thesensor, creating signals that are analyzed using thetechnology measuring changes in the concentrationof glucose under the skin (which enters the skin fromthe blood vessels). Therefore, the user wearing thedevice is able to obtain their blood-sugar levels in realtime. By enabling users to measure their blood-sugar
levels easily and in real time, this technology canensure that patients classified as pre-diabetic can eat
many of their favorite foods while keeping an eye on
their levels to ensure they do not go up. Cases arebeing reported of patients who were able to bring
their blood-sugar levels from pre-diabetic to normal
within one week by sticking to a diet suited to themwhile monitoring their levels [23]. This enables people to control their blood-sugar levels on their own.
NTTʼs wearable blood glucose sensor provides a way
for patients to enjoy their food rather than having toendure a diet they do not like by thinking about the
foods they enjoy and selecting those items that do notaffect their blood-sugar level.
Does drinking coffee contract your blood vessels?
Or could it actually rejuvenate them? The antioxidants found in coffee are said to rejuvenate the bloodvessels, helping to maintain a healthy heart. However, it is also said that caffeine may cause constrictionof the blood vessels. Research by Dr. Ahmed ElSohemy, Toronto University suggests that while coffee-drinking may reduce the risk of myocardial
infarction in people with a genotype that rapidly
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This wearable device monitors blood-sugar values by being worn against the skin.
Commercially available bloodglucose monitoring device

Exhibited at R&D Forum 2022

R&D Forum 2023

This device only needs to be worn against the skin, with no needles required

https://medicommi.jp/24620

This monitors blood sugarby blood draw/pinprickhttps://brain-gr.com/tokinaika_clinic/blog/diabetes/a-tool-that-realizes-visualization-of-blood-glucose-level-has-appeared/

Fig. 6. Blood-sugar monitoring using a biodigital twin.

breaks down caffeine, drinking coffee may put stresson the heart in those whose genes cause them to break
down caffeine slowly [24].
The ability to metabolize the components found in
medications may also vary among individuals, aswith caffeine. Take as an example warfarin, which
dissolves clots in blood vessels. For Japanese, therequired daily dose of this drug can vary by a factorof 20 from patient to patient, depending on genetic
type. In other words, while some individuals can take asingle pill daily, others must take 20 pills a day [24].
Analysis of genes and electronic medical records interms of the ideal dosage of various medications fordifferent people can open up the possibility of tailormade dosage regimens and preventive medicine
adapted to each individual. NTT Life Science is issuing reports analyzing disease risk and individual
makeup in terms of alcohol metabolism as part ofNTTʼs big data analysis and its genetic testing services, which use AI.
We are also using NTTʼs large language model(LLM) “tsuzumi” to automatically construct data,
including electronic medical records, and use thesedata for analyzing individual differences. We believethat by using tsuzumi to analyze peopleʼs individual
makeup, characteristics, environments, and medical
histories, and developing sensors that can obtainvarious types of vital information through non-stressful sensing methods, it should be possible to personalize in many areas, including diet, medications, andoptimized exercise levels. By enabling optimization
NTT Technical Review

Vol. 22 No. 3 Mar. 2024of care and minimizing losses, this can also create
more sustainable, socially responsible, and environmentally friendly healthcare.
3.3 Humanity, excitement, and the five senses
3.3.1 Hearing
It was through sound that NTT first brought people
together with our first telephones, so this is an area
representing over 90 years of NTT research. With
certain sound waves, laying two sound waves overeach other with a 180-degree offset (antiphase) cancancel out interference. Since the 2020 R&D Forumwhen we first exhibited our Personalized Sound Zone
technology, which uses this principle to deliver highsound quality exclusively to the user’s ears while
minimizing leakage into the surrounding environment, we have continued to evolve this technology,
culminating in the commercialization of our earphones in 2022. We will offer an extensive lineup
under the Sonority nwm Earphones brand. As these
open earphones do not block the ears or leak sound,they are ideal for use when running, cycling, and inconstruction environments. In fact, Sonority nwm
Earphones transceivers were used by the R&D
Forum 2023 Secretariat to run the event.
3.3.2 Touch
In addition to hearing and sight, we can also use
touch to create sensations that feel a step closer to thereal world. When the stethoscope shown in Fig. 7 isplaced on someone’s chest, the heartbeat that you canhear is communicated via electric waves to the ball,29

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We created a connection between the United Nations (UN) Headquarters in New York (the venue)
and NTT headquarters in Tokyo 6800 miles away, to bring the sound of the heartbeats of childrenin Tokyo to children listening at the venue.
Children’s Conference of the Future in support of the UN:
A project announcement event in New YorkThe heartbeats sound as though
they were close by, despite being
on the other side of the world

Control circuit

Stethoscope©Masahiro Noguchi©Masahiro Noguchi

July 19, 2023: Disarmament, Demobilization and Reintegration (DDR)
at the UN Headquarters

Fig. 7. The sensation of a heartbeat transmitted from Japan to the UN.

making it vibrate. At the Children’s Conference of the
Future held in July 2023, we connected Tokyo and theUnited Nation’s New York headquarters in this way.
A boy in Tokyo (shown on the projector displayed in
the central photograph) had his heartbeat detectedwith a stethoscope. It was relayed via the Internet tothe ball set up in New York, which vibrated in synchrony with the real heartbeat. “It feels like it’s rightthere in front of me!” exclaimed the girl touching thevibrating ball.
We believe that conveying something through thesense of touch like this delivers not only instrumental
value, such as “what we can do through this,” in thesame manner as communication through screensusing the senses of sight and hearing but also intrinsic
value—the value of feeling as though a person or
object is right there in front of you. Although society
has been returning to real-life experiences following
the COVID-19 pandemic, we hope to develop technologies that can convey the sense of touch in thisway, making the real world feel close by in a way we
all want to experience.
Next, I’d like to talk about technology that makes
the user feel as though they have been sent thoughspace and time to a completely different location. By
recording the vibration sounds of a real-world bikerace and the bumps and depressions of the race track
surface and converting all this into data, we can recreate these sensations for a user riding a bike in the
metaverse, including the way the vibrations change
NTT Technical Review

Vol. 22 No. 3 Mar. 2024with the different road surfaces and speeds.
3.3.3 Human augmentation
Moving beyond hearing, sight, and touch, the worldof human augmentation enables us to experienceabilities that go beyond our natural capacity. As wehave explored and exploited the technologies thatconnect people together, the scope of what we areable to communicate to other people has grown overtime. By digitalizing various phenomena, convertingthem into information and data, and using AI to analyze them efficiently and at low cost thanks to IOWN,
we can deliver not only visualization, optimization,and energy-saving but also personalization as values.
Our hope is to bring these values back to the notionsof humanity and the five human senses in the context
of social activities including food, shelter, and clothing; healthcare; and entertainment, while using thesevalues to build a future centered on individual wellbeing and social well-being that cares for the planet.
AI can set out information systematically and present us with options; however, deciding how we feel
about these options and what kind of future we wantto have are tasks that require the powers of imagination and conceptualization using the five senses thathumans possess.
We want our R&D to be about imagining and creating the sustainable yet exciting future that is coming
together in our minds as we use our imaginations tocreate a vision of people, society, and the planet.

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4. Concluding remarks
Four years since the announcement of IOWN, I
truly hope that you can now feel this idea coming tolife and imagine the exciting future that will ultimately make it possible.
References
[1]
[2]
[3]
[4]
[5]

[6]

[7]
[8]
[9]

New Energy and Industrial Technology Development Organization(NEDO), “Material of International Symposium on Photonics andElectronics Convergence,” June 2015.
Cabinet Office of Japan, “Monthly Economic Report,” Dec. 2018 (inJapanese).
Center for Low Carbon Society Strategy, Japan Science and Technology Agency, “Impact of Progress of Information Society on Energy
Consumption,” Vol. 2 (Feb. 2021) and Vol. 4 (Feb. 2022).
Fuji Chimera Research Institute, “Datacenter Business Market Survey
2022 (Market Edition),” 2022.
Data Centre Dynamics, “Digital Realty Acquires 9 Acres for 20MW
Data Center in Amsterdam, the Netherlands,” June 2023. https://www.datacenterdynamics.com/en/news/digital-realty-acquires9-acres-for-20mw-data-center-in-amsterdam-the-netherlands/
T. Sadaka, “Datacenter Market Trends 2022—Market Growth andElectricity Problem,” InfoCom T&S World Trend Report, June 2022
(in Japanese). https://www.icr.co.jp/newsletter/wtr398-20220613sadaka.html
W.Media, “New Conditions for Data Centres in Singapore to Kick infrom Q2-2022,” Jan. 2022. https://w.media/new-conditions-for-datacentres-in-singapore-to-kick-in-from-q2-2022/
OPTAGE, “A Cause of Electricity Shortage in the Near Future!?—Forefront of Electricity Problem Concerning Datacenters,” Aug. 2022
(in Japanese). https://biz.optage.co.jp/article/20220817/p2/
Teikoku Databank, “Survey of Price Change in Major 105 Food Com-NTT Technical Review

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panies (Jan. 2023),” 2023.
[10] Energy Information Center, “Unit Price of Electricity and Gas (Oct.
2022),” 2022.
[11] Japan Institute of Logistics Systems, “Ratio of Logistics Costs toSales (FY2021),” 2021.
[12] GD Freak, “Price Index of Packaging Materials (Dec. 2022),” 2022.
[13] Ministry of Agriculture, Forestry and Fisheries (MAFF), “Food Selfsufficiency Rate,” aff, Feb. 2023 (in Japanese). https://www.maff.
go.jp/j/pr/aff/2302/spe1_02.html[14] MAFF, “An Analysis of Agricultural Labor Force,” 2022.
[15] MAFF, “Census of Agriculture and Forestry,” 2022.
[16] Ocean and Climate Platform, “The Interactions between Ocean andClimate—6 fact sheets for the general public,” 2016. https://www.
ocean-climate.org/wp-content/uploads/2016/10/161011_FactSheets_
EN.pdf[17] Fisheries Agency, “Summary of Inspections Concerning the Issue of
Low Catches,” 2021.
[18] MAFF, “White Paper on Fisheries,” 2022.
[19] Food and Agriculture Organization of the United Nations (FAO),“The State of World Fisheries and Aquaculture,” 2022.
[20] D. Zeevi, D. Zeevi, T. Korem, N. Zmora, D. Israeli, D. Rothschild, A.
Weinberger, O. Ben-Yacov, D. Lador, T. Avnit-Sagi, M. Lotan-Pompan, J. Suez, J. Ali Mahdi, E. Matot, G. Malka, N. Kosower, M. Rein,
G. Zilberman-Schapira, L. Dohnalova, M. Pevsner-Fischer, R.
Bikovsky, Z. Halpern, E. Elinav, and E. Segal, “Personalized Nutrition by Prediction of Glycemic Responses,” Cell, Vol. 163, No. 5, pp.
1079–1094, 2015.
[21] International Diabetes Federation, “IDF Diabetes Atlas,” 10th Edition, 2021.
[22] Press release issued by Juntendo University and Japan Agency for
Medical Research and Development, Jan. 2021 (in Japanese). https://www.amed.go.jp/news/seika/kenkyu/20210115-02.html[23] NHK, “Today’s Close-up,” Aug. 30, 2012 (in Japanese). https://www.
nhk.or.jp/gendai/articles/3239/[24] NHK, “Special Program on The Human Body (Jintai),” May 5, 2021
(in Japanese). https://www.nhk.or.jp/kenko/atc_969.html

31

Feature Articles: Keynote Speeches at NTT R&D
FORUM 2023 — IOWN ACCELERATION

LLM+×IOWN —The Advancementof IOWN, the Launch of NTT’s LLM,
and Their Synergy—
Shingo Kinoshita
Senior Vice President, Head of Researchand Development Planning,
NTT Corporation
Abstract

This article presents tsuzumi, NTT’s large language model (LLM), andthe advancement of the Innovative Optical and Wireless Network(IOWN). It is based on the keynote speech given by Shingo Kinoshita,senior vice president, head of Research and Development Planning of
NTT Corporation, at the “NTT R&D FORUM 2023 ― IOWN ACCELERATION” held from November 14th to 17th, 2023.
Keywords: large language model, IOWN, photonics-electronics convergence, AI

1. Launch of NTT’s large language model
We announced at a press conference on November
1 that we have developed tsuzumi, NTT’s large language model (LLM). This LLM has four main features.
1.1 LightweightIts first feature is that it is lightweight. Today’s
LLMs are in competition for the number of parameters, thus becoming very large in scale. As such, thechallenge now is achieving sustainability. For example, OpenAI’s Generative Pre-trained Transformer 3(GPT-3) has 175B parameters and requires about
1300 MWh of electricity for one training session.
This is equivalent to an hour’s worth of electricity
produced by one nuclear power plant. In contrast, wehave adopted the following strategy.
In terms of direction being pursued, we do not aim
to build one massive LLM that knows everything but
small LLMs with specialized knowledge. Our
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Vol. 22 No. 3 Mar. 2024

approach to this is not simply to increase the parameter size but to make the LLM smarter by improving
the quality and quantity of training data added to it.
Therefore, we developed and announced two types of
tsuzumi. The ultralight version, tsuzumi-0.6B, is0.6B in parameter size, which is about 1/300th that of
GPT-3. The light version, tsuzumi-7B, is 1/25th thatof GPT-3.
What are the benefits of reducing size? The first isthat training can be carried out at very low cost. For
example, GPT-3-scale training is said to cost about
470 million yen per session. In contrast, tsuzumi-7B
and tsuzumi-0.6B cost 19 and 1.6 million yen,respectively, enabling reduction in costs by 1/25 and1/300. The second benefit is the cost of inference, i.e.,the cost of using the LLM. For example, GPT-3
would need about 5 high-end graphics processing
units (GPUs), which cost about 15 million yen. The
7B and 0.6B versions, however, would cost about 0.7
and 0.2 million yen, respectively. In terms of thenumber of GPUs, cost is reduced with the use of only32

Feature Articles

tsuzumi

GPT-3.5

Fig. 1. Comparison of tsuzumi and GPT-3.5.

one low-end GPU and only one central processing
unit (CPU), respectively.
1.2 Proficiency in Japanese
Its second feature is its high linguistic proficiency,
especially in the Japanese language. Figure 1 shows
example answers of tsuzumi on the left and GPT-3.5
on the right to a question about the current situationand possible improvement measures for attaining abalance between Japan’s energy policies and environmental protection. The left answer presents a wellanalyzed response in Japanese. Comparisons of tsuzumi with GPT-3 and other LLMs were made using
the Rakuda benchmarks. For example, tsuzumi wascompared against GPT-3.5. They were asked thesame questions, and their answers were input to
GPT-4 to determine which gave the better answer andwhich is superior or inferior. As a result, tsuzumi beatGPT-3.5 at 52.5% probability. Comparisons with thefour top-class LLMs in Japan revealed that tsuzumi
had an overwhelming win rate of 71.3 to 97.5%.
Furthermore, tsuzumi can not only give answers inJapanese to questions in Japanese. For example,
when tsuzumi was asked to extract four data items,
namely, device name, achievement, exhibition event,and future plans in JSON format from a text of a
recent press release about an artificial photosynthesis
device developed by NTT, it gave a properly structured response as requested. Its performance in English is in fact on par with the world’s top-level language models. In comparison to Llama 2, an English
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language model developed by Meta, tsuzumi produced almost the same English benchmark results.
For example, tsuzumi gave a smooth and quick
response when asked to translate the Japanese text
into English. It is also proficient in programming
language. When asked to write code in a specific format, it gave a proper response in the requested format. It is currently being trained in Chinese, Korean,
Italian, and German, so it will also eventually be able
to give answers in those languages.
1.3 Flexible customization
Its third feature is flexible customization. Language
models have a base model, which can give fairly
adequate answers to general questions. However, toconstruct models that can give specific answers in thefield of finance or the public sector, for example, tuning must be executed. There are three tuning methods
available (Fig. 2). On the left of Fig. 2 is a method
called prompt engineering. With this method, prompt
inputs to the base model are added with financial
information to enable the model to give a morefinance-specific response. In the middle is a method
called full fine-tuning, which creates a model specialized in finance by re-training the base model withfinancial data and changing the entire set of parameters. On the right is a method called adapter tuning,with which the base model is used as is, and theseblue adapter components on finance-specific knowledge are added on top of the base model like a hat.
They have different advantages and disadvantages in33

Feature Articles• Three tuning methods for flexibly responding to different requirements such as accuracy and cost
Prompt engineering

Full fine-tuning

Adapter tuning

Cost

Very good

NeutralGood

Accuracy

NeutralVery goodGood

Add financial
information to prompts

Finance

Ba

se

mo

FinancedelFig. 2. Different tuning methods.

After fine-tuning

Before tuning

Answer the oldmarket segments

Correctly answer the new market segments of the Tokyo
Stock Exchange, which changed on April 4, 2022

Fig. 3. Example of fine-tuning in financial industry.

terms of cost and accuracy. As an example of theadvantage of tuning, the base model can be mademore specific to a particular industry, company, ororganization or can be updated with the latest information. One can also add functions by training themodel with new tasks, such as summarization andtranslation, to make it more task specific.
Figure 3 shows an example of fine-tuning in thefinancial industry. On the right is the response using
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Vol. 22 No. 3 Mar. 2024

data before tuning, and on the left is the response afterfine-tuning the data for the financial industry. LLM
tsuzumi was asked to explain the market segments of
the Tokyo Stock Exchange (TSE). The right responseshows the old segments, such as 1st section, 2nd section, JASDAQ, and Mothers. The left response shows
the new segments established by TSE on April 4,2022. The LLM properly learned and gave the correct
segments, i.e., Prime, Standard, and Growth.
34

Feature Articles

What percentage of power
consumption is expected tobe reduced by IOWN in
2040?

Call

Clear

Exe.

−45%

Fig. 4. Modality extension: Language + Visual.

1.4 Multimodality
Its fourth feature is multimodality. Language models in general have received language inputs andproduced language outputs. Multimodality refers to
the ability to handle modals other than language. For
example, one can now add visual and audio capabilities. For example, when tsuzumi was shown a receipt
and asked, “What is the total amount excluding the
10% consumption tax?” It then calculated the total bylooking at the unit price and quantity columns on thereceipt and correctly replied that the total is 9500 yen.
Figure 4 shows another example. This is a graphfrom NTT’s Green Vision. While being shown thiscomplicated graph, tsuzumi was asked “What percentage of power consumption is expected to be
reduced by IOWN in 2040?” It correctly analyzed thegraph and replied 45%. Thus, it is capable of providing answers by analyzing the question in combination
with figures.
2. Technological capabilities ofNTT laboratories
Next, I would like to talk about the technologicalcapabilities of NTT laboratories that enabled us toachieve these four excellent features.
Figure 5 shows a table listing the ranking of companies based on the number of publications in thefield of artificial intelligence (AI). NTT is ranked
12th in the world and 1st in Japan in this report published annually by a U.S. venture capital firm. In the
top 1 to 11 are GAFA (Google, Apple, Facebook, andAmazon) and other major information technology
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Vol. 22 No. 3 Mar. 2024

(IT) vendors in the U.S. and China. Compared with
NTT, they probably have ten times more researchfunding and have many times more researchers. Nevertheless, NTT has been able to conduct researchquite efficiently, enabling us to achieve these rankings. In AI, natural language processing is a very
important area in the development of language models. NTT is number one in Japan in terms of the number of publications in this particular area. It is also
number one in the number of awards for excellence
given by the Japanese Association for Natural Language Processing. The development of tsuzumi isbacked by a long history and solid track record inresearch. We used excellent data for training tsuzumi,
which is its distinguishing feature. We used morethan 1T tokens, which can be thought of as the number of words, for pre-training. We used not only Japanese and English but also 21 other languages as wellas programming languages to train tsuzumi. These
data cover a very wide range of domains, from specialized fields to entertainment. For instruction tuning, which makes the pre-trained data more humanlike in response and behavior, we used Japanese corpora created from NTT’s over more than 40 years of
research. We also used new tuning data we createdspecifically for generative AI.
In this R&D forum, we presented 11 exhibits on
tsuzumi. I will briefly introduce representative exhibits in the following sections.
2.1 L
 LM tsuzumi comprehensively understands
the real world
A supervisor and junior member are having a
35

Feature Articles

Rank
1
2
3
4
5
6
7
8
9
10
11

Company nameGoogle (USA)
Microsoft (USA)
Facebook (USA)Amazon (USA)IBM (USA)
Huawei (China)
Alibaba (China)
NVIDIA (USA)
Tencent (China)
Samsung (South Korea)
Baidu (China)

12

NTT (Japan)

13
14
15
16
17
18

Apple (USA)
OpenAI (USA)Intel (USA)
Adobe (USA)
Salesforce (USA)
Yandex (Russia)

19

NEC (Japan)

20

VinAI (Vietnam)

Top 100 Global Companies Leading in AI Research in 2022*1*1 https://thundermark.medium.com/ai-research-rankings-2022-sputnik-moment-for-china-64b693386a4

Fig. 5. Number of AI publications: 12th in the world & 1st in Japan.

• Multimodal comprehension of communication between supervisors and junior members to address powerharassment by supervisors
Facial expressions

SpeechLevel ofLevel ofharassment interruption

Fig. 6. LLM tsuzumi comprehensively understands the real world.

conversation via online communication, during
which the supervisor displays power-harassment
behavior. LLM tsuzumi detects the power-harassment behavior and calls it to the supervisor’s attention. “I’m sorry. I’m a little busy with other jobs so I
couldn’t reply immediately.” “If you’re busy withother work, isn’t it your basic responsibility as aworking adult to report that, too?” The person on the
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left of Fig. 6 is the supervisor making power-harassment statements. The LLM then analyzes the emotions on the basis of the supervisor’s facial expressions and speech. It determines to what degree theperson is laughing or angry as percentages. The blue
area on the left in the below column shows what thesupervisor said. The middle shows that the level ofharassment is about 71%. It also shows a 73% level36Feature Articles• Creation of specific travel plans on the basis of user attributes and preferences, taking into account road-congestion
conditions and other factors

Tomorrow, after themining experience at the
Ashio Copper Mines, I
plan to try Utsunomiya’s
famous gyoza. My son isinterested in geology andis excited about ore
mining. The whole family
also loves gyoza and islooking forward to
Utsunomiya’s specialty.

Departure time

Nov. 25 (Thu)
7:00 am

Departure point

Shibuya City

Final destination
Travel destination 1

Hotel in Utsunomiya
City
Mining experience at
Ashio Copper Mine

Travel destination 2

Eat gyoza in
Utsunomiya

User attributes

Male, 40s

Passengers

Wife, son (junior highschool student)

Directions

Hotelreservation

Restaurant
reservation

Fig. 7. LLM tsuzumi understands the user situation.

of interruption while the other person is speaking.
These percentages show a relatively high level ofharassment. In response, as shown in the pink area,
tsuzumi gives advice to encourage behavioral change
in the supervisor. It says, “While it is important toproperly report on their work, it is also important toencourage junior members to do so. An effective way
to encourage them is for the supervisor to create
opportunities to check on junior members on a regular basis and adjust their workload as necessary. It isalso important to listen patiently to junior members tocreate an environment in which they can work withpeace of mind.” Thus, tsuzumi can give appropriate
advice to supervisors to address their behavior.
2.2 LLM tsuzumi understands user situations
LLM tsuzumi can create specific travel plans on thebasis of user attributes and preferences, taking into
account road-congestion conditions and other factors.
The gray text on the left of Fig. 7 shows the user’s
requests. It says, “Tomorrow, after the mining experience at the Ashio Copper Mines, I plan to try Utsunomiya’s famous gyoza. My son is interested in geology and is excited about ore mining. The wholefamily also loves gyoza and is looking forward to
Utsunomiya’s specialty.” Once the car-navigation
system with tsuzumi hears this, it structures and analyzes the inputs into specific information such as
departure time and departure point, as shown in the
middle. It then searches the web to gather informaNTT Technical Review

Vol. 22 No. 3 Mar. 2024

tion on directions, hotel reservations, and restaurant
reservations. Finally, it creates an action or travel
plan to propose to the user.
2.3 L
 LM tsuzumi with physical senses and arobot body
A robot equipped with tsuzumi can create a menu
and set a table according to the user’s request. In thisexample, the user says, “Prepare a dinner table thatwill warm the body up on a cold winter’s day. Make
considerations for left-handedness.” The robot thenanalyzes the request and actually serves the food
while explaining the arrangement. For example, itsays, “Curry is good for warming the body up, andsalad. They pair well with spring rolls for a seasonalfeel. Tea warms the body, too. In consideration ofleft-handers, the chopstick and spoon are placed in
the opposite direction.” The robot servs food while
giving such explanations.
2.4 Ultra-high-speed software development
How to add a new function, i.e., a review function,
to a shopping site with tsuzumi was demonstrated.
The website on the left of Fig. 8 only gives the usual
introduction of a product, without a review function.
One can then instruct tsuzumi to add a product review
function. In response, it analyzes the source code andcarries out these actions. The demonstration showed
how tsuzumi can write a new source code to create areview section on a website.
37

Feature Articles• Demonstration of adding a new function (review function) to a shopping site using tsuzumi
A review function is added.

Instruct what you develop.
Add a product review function.

BeforeAfter

OK. Review functions will be implemented in eachproduct page. Product pages are implemented with“item.html” and “ItemController.java”. These files will berevised. Please wait for a while.

Fig. 8. Ultra-high-speed software development.

2.5 Next-generation security operations
LLM tsuzumi can handle incident responses onbehalf of security experts in a dialogue format. For
example, if a virus is detected on a user’s computer,tsuzumi analyzes the virus, informs the user, asks theuser whether they have accessed the malicious site,
and instructs the user to respond as soon as possible
via chat. The demonstration showed how tsuzumi
interacts with the user step by step to urge users to
respond to security issues.
2.6 Phishing-site detection
LLM tsuzumi analyzes the input website and determines whether it is a phishing site. It’s accuracy indetecting phishing sites is more than 98%, which ismuch more accurate than checking by humans.
3. Advancement of IOWN
Next, I would like to move on to the advancementof the Innovative Optical and Wireless Network(IOWN). First, I would like to explain the IOWN
roadmap (Fig. 9). IOWN1.0 is a networking technology that connects datacenters (DCs) using opticalfiber. IOWN2.0 optically links the boards inside theserver in the DC. Evolving further, IOWN3.0 will
optically connect the chips, while IOWN4.0 will
enable optical connection inside the chip. Now, let’slook at the roadmap by generation. There are a numNTT Technical Review

Vol. 22 No. 3 Mar. 2024

ber of elemental technologies that make up IOWN foreach generation. An example is a device called thephotonics-electronics convergence (PEC) device.
Along with the evolution of IOWN generations 1.0 to
4.0, PEC will also continue to evolve from the 2nd to
the 3rd, 4th, and 5th generations. The All-Photonics
Network (APN) will evolve within IOWN1.0 throughthe addition of functions and increasing performance.
The super white box of the data-centric infrastructure(DCI) will evolve from IOWN1.0, to 2.0, and to 3.0,
along with the evolution of PEC devices, as Steps 0,
1, and 2. This roadmap shows how we will be moving
forward with the advancement of these technologies.
I’ll now introduce what we achieved for IOWN1.0
in 2023. One achievement is the significant progressin the commercialization of the APN. The APN consists of APN-I for the core network, APN-G for theedge network, APN-T installed in the user base, andOTN (Optical Transport Network) Anywhere in theuser terminals. Different companies have launchedspecific products for the APN. In March 2023, NTT
EAST and NTT WEST began providing specific network services using these products. This 100-gigabyte leased-line service enables users exclusive useof optical wavelengths from end to end. Using OTN
Anywhere enables visualizing latency and provides
functions for adjusting and aligning different delay
times. Using this service, we have conducted various
proofs of concept (PoCs), and many PoCs were in the38

Feature Articles

2023

2025

2027

2029

and onward

IOWN4.0

PEC 5th Gen

Computing

Inside Chip

DCI step2

IOWN3.0
Chip to Chip

PEC 4th Gen
DCI step1

IOWN2.0

PEC 3rd Gen

Networking

Board to Board

DCI step0

IOWN1.0

APN step1

APN step2

APN step3

DC to DCPEC 2nd Gen
Photonics-electronics convergence technology application areas
DCI: data-centric infrastructure

APN: All-Photonics Network

PEC: photonics-electronics convergence device

Fig. 9. Progress of IOWN.

entertainment field such as for concerts, e-sports,
comedy, and dance.
Other than entertainment, we plan to use the APN
to construct DCs of the future. Thus far, the range ofDC-to-DC connections has been limited because ofsignificant delays in conventional networks. The
limit is about 60 km, but there is not enough land
within this range, making it difficult to add more
DCs. If the connection distance between DCs can beincreased from 60 to 100 km by using the APN, thenthere will be more land available for constructing
connected DCs. We believe that the APN is highly
suitable for such expansion of connected DCs. We are
currently conducting demonstration experiments at
various locations to achieve this. By expanding
beyond the Tokyo metropolitan area to major cities
throughout Japan and even to other parts of the world,
we believe that it will be possible to build a global
APN network.
Next, I will report on the status of IOWN2.0 and
3.0. The first is concerning DCI. DCI is a next-generation computing architecture for achieving high performance with low power consumption by allocating
optimally subdivided computer resources centered ondata (Fig. 10).
In Step 0, the units for computer-resource subdivision are the server and storage, and the APN is used
for connecting them. In Step 1, the unit of subdivision
is the board inside the server. By connecting boards
with a 3rd-generation PEC device, we aim to achieve
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ultra-low power consumption and ultra-high-speed
switching. In Step 2, computing resources are subdivided by chip units, which will be connected with a
4th-generation PEC device. This will enable achieving even lower power consumption and higher performance. The key device to achieve Step 1 is the
3rd-generation PEC device called the optical engine.
The yellow areas of Step 2 in Fig. 10 correspond toeach optical engine. We have been conducting experiments with Broadcom on this chip in the middle,
which has a switching capacity of about 5 Tbit/s, witheach optical engine having a transmission capacity of
3.2 Tbit/s. It is therefore possible to configure a single
device with 5 Tbit/s of switching capacity. The 4thgeneration PEC device will optically connect chips at
an implementation efficiency six times higher and apower efficiency two times higher than the 3rd generation. This will enable further improved performance and lowering power consumption.
4. Synergy between LLMs and IOWN
The third topic is about the synergy between LLMs
and IOWN. For IOWN, we are conducting experiments combining DCI Step 0, the APN, and LLMs.
We have this amount of training data in Yokosuka andwanted to install GPUs nearby, but there was notenough power or space. Therefore, we used a GPU
cloud in Mitaka and connected it with the database in
Yokosuka by the APN for remote access. At this39

Feature Articles• An architecture that subdivides computing resources and optimally combines them in accordance with the
purpose of data processing• The APN and PEC technologies are used to connect subdivided computing resources
Step

0

Step

1

Step

NIC

3rd Gen.

2

4th Gen.

APN
Optical switch

Computing-resource subdivision unit

Server/storage unit

Board unit

Chip unit

3rd-generation PEC
device connection

4th-generation PEC
device connection

Subdivided-resource-connection method

APN connection
ASIC: application-specific integrated circuit
FPGA: field-programmable gate array
NIC: network interface card

Fig. 10. DCI.

distance, the network file system would be quite slow
and there would be considerable performance degradation. With the APN, however, we were able toachieve connection with almost zero performancedegradation even at 100-km distance. Specifically,
the performance degraded only by about 0.5%. By
optically connecting each CPU and GPU directly
using an optical switch, we can carry out LLM training and inference with the minimal and optimized
combination of computing resources. We currently
use many GPUs to train LLMs, but many of theseGPUs are sometimes idle. We aim to implement
training with as few computer resources as possible
while making all devices work at full capacity.
NTT’s future vision for the world of AI is to create
an AI constellation. We envision a next-generation AI
architecture to more smartly and efficiently addresssocial issues by combining multiple, small, specialized LLMs, instead of creating a single monolithic
massive LLM. For example, AI with personas representing a human resources manager, clinical psychologist, truck driver, and elementary school teacher
talk about “what is needed to revitalize our shrinking
community.” They offer their opinions and come up
with a consensus on what to do, with the involvementof humans when necessary. We believe we can createa mechanism for building consensus through theseinteractions.
We formed a business partnership with sakana.ai to
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Vol. 22 No. 3 Mar. 2024

conduct joint research to build the AI constellation
mentioned above. The venture company sakana.ai isin the spotlight right now. It was founded by wellknown AI experts. David Ha was lead researcher at
Google Brain and at Stability AI, the company thatcreated Stable Diffusion image generation AI. While
Llion Jones was one of the Google developers whocreated the basic algorithm for transformers, now
being used in ChatGPT and other AIs. They established sakana.ai with a base in Japan to conduct R&Dof new LLMs and AI constellations. We have enteredinto a business partnership to work together withthem in these areas.
5. Three resolutions of NTT laboratories
Finally, I would like to conclude by talking about
the three resolutions of NTT laboratories (Fig. 11).
“Do research by drawing from the fountain of knowledge and provide specific benefits to society throughcommercial development.” These words, proclaimed
in 1950 by Goro Yoshida, the first director of theElectrical Communication Laboratory, embody thevision of NTT laboratories. They point to three elements built on top of each other. “Doing research by
drawing from the fountain of knowledge” is the foundation. On top of this is the phase of “commercial
development,” and, on the topmost is “providing
specific benefits to society.”40Feature Articles

Provide specific benefits
to society
Through commercial development
Do research by drawing from the fountain ofknowledge

Fig. 11. Three resolutions of NTT laboratories.

Rank

CompanyCountry/Region

No. ofpapers

1

IBM

USA

8096

2

Microsoft

USA

7050

3

Siemens

GERMANY

6628

4

Samsung

SOUTH KOREA

6353

5

Google

USA

5926

6

Huawei Technologies

CHINA

5392

7

Intel Corporation

USA

4982

8

SINTEFNORWAY

4602

9

General Electric

USA

4309

10

Philips

NETHERLANDS

3822

11

NTT

JAPAN

3439

12

Nokia Corporation

FINLAND

3352

13

Bosch

GERMANY

2821

14

Samsung Electronics

SOUTH KOREA

2782

15

China Electronics Technology

CHINA

2727

Source: Survey by NTT using Web of Science, InCites Benchmarking

Fig. 12. Research publications ranking: 11th in the world & 1st in Japan (ICT and engineering companies, 2017–2021).

The most important is the research at the bottom,
done “by drawing from the fountain of knowledge.”
Not only in AI, as mentioned earlier, but also in allengineering fields, NTT is ranked 11th in the world in
the number of publications (Fig. 12). In world-classresearch areas, such as speech recognition, information security, optical communications, and quantum
computing, NTT boasts the world’s highest numberof publications, beating Google and IBM. We would
like to build on these accomplishments and solidify
our position as a world leader in research by further
aiming for the top and expanding our world-classresearch areas. This is our first resolution.
Next is the phase of “commercial development” inthe middle. IOWN and LLMs are the two key technologies that we would like to robustly develop and
put into commercial use as an embodiment of our

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Vol. 22 No. 3 Mar. 2024

second resolution.
Last is the social implementation phase of “providing specific benefits to society.” In this regard, wenewly established the Research and Development
Market Strategy Division in June 2023. Thus far, thelaboratories and the Research and Development Planning Department, to which I belong, have been working together in various ways with customers, partnercompanies, and business companies. Under the neworganization, we established the Marketing Planningand Analysis Department, wherein the Research andDevelopment Planning Department will work together with both the Marketing Planning and Analysis
Department and Alliance Department to enhance andbroaden the scope of our activities. Thus, our third
resolution is to implement research and development
results into society going forward.

41

Feature Articles: Efforts in the Environmental and Energy
Sector to Create a Sustainable and Resilient Society

Forefront Initiatives of NTT Space
Environment and Energy
Laboratories
Yuji Maeda
Abstract

Having established unconventional research themes that had not been targeted at NTT laboratories,
NTT Space Environment and Energy Laboratories is taking on various challenges to change the futureof the global environment. By looking at the Earth from the perspective of space, we are aiming toregenerate the global environment and create an inclusive and sustainable society. In this article, the latest activities and future prospects of NTT Space Environment and Energy Laboratories, which has
existed for three and a half years, are introduced.
Keywords: space, environment, energy

1. Introduction
NTT Space Environment and Energy Laboratories
was established in July 2020 to contribute to the revitalization and reform of the global environment. We
will achieve this by reviewing the Earth and social
environment we live in from the broad perspective of
space above the Earth in a manner that is not boundedby the conventional framework of environment andenergy. Three and a half years after our establishment, we have revised our vision as follows: “Withthe ultimate goal of regenerating the global environment and creating an inclusive and sustainable society, we aim to create innovative next-generationenergy technology and resilient environmental adaptation technology and contribute to achieving zeroenvironmental impact.”
The specific image of society that we hope to create
through this new vision is the “sustainable and resilient society” described in the title of the Feature
Articles. This is a society in which the impact of thesociety we live in on the global environment isreduced to zero and the varying impact that global
environment changes have on society can be mitigated flexibly. This society will be based on the following innovations (i) next-generation energy techNTT Technical Review

Vol. 22 No. 3 Mar. 2024

nologies such as nuclear fusion and space power
generation; (ii) zero power outages through local
production and local consumption of clean energy,
and autonomous, decentralized, and coordinatedenergy networks; (iii) reduction of carbon dioxide(CO2) in the atmosphere and oceans through circular
agriculture, forestry, and fisheries; and (iv) the use ofhighly accurate future prediction to not only prevent
damage caused by natural disasters but also extractenergy from typhoons and lightning (“disaster green
energy”).
We have been working hard to establish researchsystems, increase the number of researchers, collaborate with many research institutions, and quickly
generate research results. We have frequently updated our owned media “Beyond Our Planet” [1] to raiseawareness of the Laboratories and strengthen ouracquisition of external human resources. The numberof page views of articles on linear rainbands, in conjunction with sudden rainstorms and typhoon strikes,
has increased significantly to about 18,000 per month(out of about 81,500 per month in June 2023 for theentire owned media), and our organization and activities have been highly ranked by search engines in amanner that shows we are gaining social recognition.
To accelerate the digital twinning of the global
42

Feature Articles

Zero environmental
impactNext-generationenergy technology

Contribute to zero environmental
impact and mitigate the impact ofclimate change
Energy network
technology

Adapt to the impact ofclimate change with
forecasting

Main areas
Agriculture,affected byclimate change forestry &fisheries
Society

Energy• Virtual energy demand/supply
control technology• Next-generation energy supply
technology

Environmental
adaptation• Optimized nuclear fusion operation technology• Space solar power generation technology

Creationof Resilient
Society

Infrastructure

Proactive
environmental
adaptation technology• Lightning attracting/lightning
charging technology• Cosmic-ray
electromagnetic-barrier
technology

PeopleIndustry

Corporate
strategy

ESG management
science andtechnology• ESG futures forecasting methodology• ESG intelligence scientific methodology

Sustainable systemtechnology• Atmospheric CO2 conversion technology• Ocean CO2 conversion technology• Soil CO2 emission control technology• Asbestos detoxification and removal technology

Biodiversity

Globalenvironment
Geopoliticalrisk

Global environmental futures
forecasting technology• Super-wide atmosphere and ocean observation technology• Weather and climate recovery modeling technology• Ecosystem recovery modeling technology• Global environment recovery simulation technology

Water

Environment andsocioeconomic nexus
forecasting technology• Collaboration of models in different fields• Evaluation indicators for environment and socioeconomic cycles

Fig. 1. Overall view of research themes.

environment and establishment of highly accurate
future-forecasting technology, the Environment andSocioeconomic Nexus Forecasting Technology
Group was established in October 2023. The numberof researchers has increased 1.8 times since the establishment of the Laboratories, and more than 40 collaborations with external organizations and universities, including startups, have begun to produce avariety of results.
The research themes we are currently focusing on
are shown in Fig. 1. NTT Space Environment andEnergy Laboratories has separated these themes into
two projects: the Zero Environmental Impact
Research Project (at the top of the figure) and the
Resilient Environmental Adaptation Research Project (at the bottom of the figure). Three researchgroups are involved in the Zero Environmental
Impact Research Project, and four groups (including
the newly established Environment and Socioeconomic Nexus Forecasting Technology Group) are
involved in the Resilient Environmental Adaptation
Research Project, and each group is pursuing researchin collaboration with the others.
As shown in the center of Fig. 1, we aim to apply
the results of our research to eight areas affected byclimate change. Therefore, we hope to reach our goalof creating a sustainable and resilient society byregenerating the global environment and reducing theeffects of climate change while maintaining a balance
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Vol. 22 No. 3 Mar. 2024

among the global environment, society, and people.
Each project and its current status are described hereafter.
2. Forefront initiatives of Zero Environmental
Impact Research Project
To contribute to NTT Group’s vision of zero environmental impact, this project is focused on researching the following three technologies: (i) next-generation energy technology that is overwhelmingly clean
and innovative, (ii) energy network technology that
efficiently handles supply and demand of renewableenergy, and (iii) sustainable system technology that
reduces atmospheric and marine CO2 through circular agriculture, forestry, and fisheries.
We are currently working on two themes regarding
next-generation energy technology. The first is “optimum fusion reactor operation technology” for fusion
power generation, a dream energy source. Fusion
power generation is a safe and clean energy sourcethat reproduces—on the Earth—the physical phenomenon occurring on the Sun, and it is being
researched worldwide with the aim of commercialization by 2050. In collaboration with the National
Institutes of Quantum Science and Technology(QST) and the ITER Organization, we are pursuingresearch on using NTT’s Innovative Optical andWireless Network (IOWN) to control the stability of43

Feature Articles

Residual CO2 in the atmosphere
2.2%

Emission Absorption
from theby theoceansoceans2845.3
2915

34.2%

35.1%

Emissionby humanactivities
403.3

4.9%

Human
Hu
activities
acti

Ocean
O
n
(Unit: 100-million
100-m
million tons CO2/year)%%

Absorption by land
Emission fromland (including Emission (including living
by otherthings)living things)
factors5206.75012.3
47.7

60.3%

0.6%

62.7%

Land
*Prepared on the basis of IPCC Sixth Assessment Report (AR6)Percentage of thet amountamoun
nt of a given CO2 emi
emission to the total amount of CO2 emission into the atmosphere
Percentage of the amount of a given CO2 absorption and residue to the total amount of CO2 emission into the atmosphere

Fig. 2. Overall picture of global CO2 flux.

plasma in fusion reactors. Venture companies are currently playing a prominent role in this field, and while
exploring global trends, we are looking to form newpartnerships with ventures and institutions that canuse our technology. As the first step of such collaborations, we have started a joint experiment on anomaly prediction with the ITER Organization [2].
The other is “space solar power technology,” whichenables large amounts of energy obtained in space tobe transmitted wirelessly to the ground in an efficientmanner. As a grand research theme, space solar
power generated from sunlight captured by geostationary satellites (about 36,000 km above the Earth)is wirelessly transmitted to the ground day and night
via laser beams and microwaves. This theme is
explained in detail in an article in this issue titled“Long-distance Laser-energy Transmission for Space
Solar Power Systems and Their Application on
Earth” [3].
To maximize the use of renewable energy regarding
energy network technology, we are researching two
technologies: (i) virtual energy-demand/supply control technology that absorbs fluctuations in renewableenergy output through integrated control of information processing by information and communication
technology (ICT) devices in NTT’s datacenters, storage batteries, and electric vehicles (ii) and next-generation energy supply technology that enables local
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Vol. 22 No. 3 Mar. 2024

production for local consumption and ultra-resilient
supply of renewable energy by using safe and highly
reliable direct-current power supply.
Virtual energy-demand/supply control technology
is beginning to attract attention as a new concept
called “power to data”, namely, surplus power fromrenewable energy is replaced with data (information
processing) for efficient consumption. In collaboration with NTT operating companies, we have started
to experimentally demonstrate this technology byconnecting our laboratory to an actual datacenter. We
plan to increase the number of connection sites andproceed with verification of this technology for practical use.
Regarding sustainable system technology, we areresearching CO2-conversion technology to reduce
CO2 in the atmosphere and oceans through circular
agriculture, forestry, and fisheries. Carbon neutrality
is often thought of as the reduction of CO2 emitted
from human activities, mainly from energy sources;
however, the amount of CO2 emitted from humanactivities account for only 4.9% of the global CO2
emissions.
The latest data on the global CO2 cycle is shown in
Fig. 2. We have previously referred to the figures inthe draft version of the Sixth Assessment Report of
the Intergovernmental Panel on Climate Change(IPCC), but Fig. 2 shows the figures prepared with44

Feature Articles

Proactive environmental
adaptation technology

Human-activity model and predictions
Politics

Cosmic-ray
Lightningelectromagnetic-barrier attracting/charging
technology
technology

Society

Environment and socioeconomic nexus
simulation platform

ESG management scienceand technology

Ecosystem

Model integration and circulation-evaluation index
Society

Collaborating models
in different fields(coupling/lightening)

Environment

EconomyCirculation simulation

Ocean

Implementation

Implementation

EconomyGlobal environmental modeland predictions
ClimateEarth-future prediction
Implementation

Environment

ESG strategicadaptation
technology

Applications

Technology
Company selection

Weather-control
technology

Atmosphere

Global environmental
futures forecasting technology

Evaluation indicatorsfor environmental andsocioeconomic cycles

Environment and socioeconomic
nexus forecasting technology

Fig. 3. Resilient Environmental Adaptation Research Project.

reference to the final version. The land (including living things) emits the largest amount of CO2 (60.3% of
the total annual amount of CO2 emission into theatmosphere), and the oceans emit 34.2% of the totalof CO2 emission. The land (including living things)
absorbs 62.7% of the total amount of CO2 emission
into the atmosphere, and the oceans absorb 35.1%. In
other words, it is, of course, important to reduce
emissions from human activities to virtually zero;
however, in consideration of the balance and cycle ofthe entire planet, it is important to approach the landand oceans at the same time as reducing emissions
from human activities. We need to reduce CO2 emissions from human activities while simultaneously
stopping or tackling deforestation, soil pollution, andocean destruction and pollution. Given those needs,
we are researching technologies to reduce CO2 emissions through circular agriculture, forestry, and fisheries.
We are researching ways to increase the amount of
CO2 fixed in the long term in the ground as well as inliving things and organic matter. We are applying
genome editing to plants and algae to increase theamount of CO2 that they absorb during photosynthesis. These genome-edited plants and algae are thenfed to seafood and livestock. Thus, the amount of
CO2 in the atmosphere and oceans can be reduced by
fixing it in the food chain and cycle.
Although we call this process “genome editing,”
we are not involved in genetic modification but rather
selective breeding, which is safe. As an outcome ofthis research, we have succeeded in identifying a
NTT Technical Review

Vol. 22 No. 3 Mar. 2024

gene that dramatically improves the CO2 absorptionof algae [4]. As a regional revitalization businessbased on land-based aquaculture, NTT Green &Food, Inc., which uses the gene-edited algae thatabsorbs a large amount of CO2 as feed, started business in July 2023 [5]. Producing new results andexpanding our business has therefore become urgent.
From now onwards, we will promote the use ofmarine and terrestrial plants with dramaticallyincreased CO2 absorption and extend their use to carbon credits.
These technologies are introduced in the article
titled “Zero Environmental Impact Technology to
Achieve a Clean and Sustainable Society” [6].
3. Forefront initiatives of Resilient
Environmental Adaptation Research Project
An overall picture of the Resilient Environmental
Adaptation Research Project is shown in Fig. 3. This
project is researching environmental adaptation,
namely, predicting the future by taking into accountthe mutual influences of human activities and theglobal environment, supporting proactive management decisions on the basis of the prediction results
and avoiding or taking advantage of damage caused
by natural phenomena. We are working on establishing four technologies: (i) ESG (environmental,social, and governance) management science andtechnology that predicts future scenarios (such as
climate change) that will affect corporate managementfrom a wide range of publicly available information;45

Feature Articles(ii) global environmental futures forecasting technology that predicts the future of the global environment
through observation and modeling of physical, biological, and chemical processes in the global environment; (iii) environment and socioeconomic nexus
forecasting technology that predicts social and environmental cycles by integrating models from a variety of fields and creating new cycle-evaluation indicators; and (iv) proactive environmental adaptation
technology that combines these three technologies
and uses the results of future prediction to proactively
adapt to the social environment.
With the ESG management science and technology,
we aim to establish a future forecasting technologythat contributes to the formulation of management
strategies by combining two methods: ESG intelligence scientific methodology and ESG futures forecasting methodology. The ESG intelligence scientificmethodology collects and analyzes global public
information (such as government documents, academic conferences, and news) worldwide by using
artificial intelligence (AI), text-mining techniques,
and other methods. Information is analyzed by firstremoving human-thinking biases then generating
multiple possible scenarios by extracting causal relationships between events and plans. The ESG futures
forecasting methodology quantitatively predicts
social and environmental changes on the basis ofmultiple scenarios. For this quantitative forecasting,
we use a macroeconomic model called the computable general equilibrium (CGE) model. The CGE
model is used for mathematically predicting changes
in an overall market on the basis of production andconsumption by industry and the interactions amongindustries. For example, fluctuations in energy prices
can affect the sales volume and CO2 emissions inindustries that use a large amount of energy (e.g.,steel manufacturing and transportation). By calculating these effects by using the CGE model, we canquantitatively predict future economic and environmental impacts while taking into account the interactions between industries. Using these methods, we
can continuously forecast the combined impact ofenvironmental and social changes on management
over the short and long terms. With the ESG futures
forecasting methodology, in collaboration withresearch organizations such as the National Institutefor Environmental Studies since 2020, we have been
conducting assessments regarding the impact of ICTdevelopment on society * and disseminating theresults at international conferences. We will focus on
the ESG intelligence scientific methodology and colNTT Technical Review

Vol. 22 No. 3 Mar. 2024

laborate with the management divisions of operatingcompanies with the aim of achieving more practicalresults.
To create a flexible society that can adapt to change,
it is necessary to establish technologies for predicting
the future of the global environment. These technologies involve observation of the atmosphere andoceans over an ultra-wide area to model weather andclimate on the basis of the Earth’s physical processes
and model ecosystems on the basis of the Earth’s
biological and chemical processes. Meteorologicaland environmental observations are currently limited
to land and near-shore waters, that is, real-time observation in the distant parts of the oceans from land has
not been established. Therefore, satellite observationis the main method of such observations. However, it
is difficult for satellites to measure water vapor, theenergy source of extreme weather events, such as
typhoons and linear rainbands, as well as environmental information about the ocean. With these difficulties in mind, we are attempting real-time observations in these unexplored areas by using satellite
Internet of Things (IoT) [7] while upgrading weather
and climate models. Since it is difficult for us toestablish such sophisticated ocean observations andmodels on our own, we are also working with a variety of organizations to study this issue. Some of ourrecent accomplishments include (i) the world’s-firstsuccessful simultaneous observation of the atmosphere and ocean under a Category 5 typhoon in thenorthwest Pacific Ocean in collaboration with the
Okinawa Institute of Science and Technology Graduate University (OIST) [8] and (ii) the world’s-firstdevelopment of millimeter-wave radio frequency
identification (RFID) tags to improve drone-navigation accuracy for advanced weather observation incollaboration with the University of Tokyo [9].
The aforementioned newly established Environment and Socioeconomic Nexus Forecasting Technology Group is working on technology for forecasting environmental and socioeconomic nexuses. To
achieve inclusive sustainability, we are (i) constructing a global-scale simulation environment that reproduces the interaction between environmental andeconomic activities related to the global water cycleand (ii) researching large-scale coupled simulation
technology to link simulation systems in different
fields of expertise. These activities are described indetail in the article titled “Forecasting Technologies*

This research was funded by the Environmental Research andTechnology Development Fund of the Environmental Restoration
and Conservation Agency of Japan (JPMEERF20201002).

46

Feature Articles

Fig. 4. Experimental demonstration of a lightning-resistant drone flight on a beach in a snowstorm.

for Environmental and Socioeconomic Cycles for
Attaining Inclusive Sustainability” [10].
The proactive environmental adaptation technology predicts the future by coupling the three abovementioned technologies (ESG management scienceand technology, global environmental futures forecasting, and environment and socioeconomic nexus
forecasting) and adapts business practices to theenvironment in accordance with the prediction
results. However, it will take time to establish thesethree technologies. Therefore, we have started
research on lightning and cosmic rays, which can bepredicted to some extent even now. We are researching technology for preventing lightning-induced
damage to important equipment by capturing lightning by drones equipped with lightning rods, guiding
it to the desired location, and using lightning energy.
We are researching lightning-resistant drone technology, lightning induction technology, lightning prediction technology, and lightning charging technology.
We have completed verification of lightning-resistant drones using artificial lightning and natural lightning in the winter of 2022/2023 on the coast of Uchinada Town, Ishikawa Prefecture, which is an areawith the most winter lightning in Japan. Unfortunately, we were unable to capture natural lightning.
However, we gained much knowledge during thedemonstration in the extreme cold and quite-hazardous winter storms (Fig. 4). For example, we developed technology for predicting lightning-induction
areas by combining information on thunderclouds
and lightning strikes with information from our
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Vol. 22 No. 3 Mar. 2024

observations and technology for operating drones
under extremely bad weather conditions. Our challenge is not over yet, and to be the first in the world
to capture natural lightning with a lightning-resistantdrone, we will continue to refine this technology inwinter 2023/2024.
We have been working to improve the technology
for evaluating soft errors, namely, malfunctions ofsemiconductors in communication equipment due tocosmic rays. To further develop this technology, we
are researching cosmic-ray electromagnetic-barrier
technology for evaluating the effects of cosmic rays
on space equipment and the human body and reducing the effects of strong electromagnetic fields. This
topic is explained in detail in the article titled “Forefront Research Initiatives on Environmental Adaptation to Enhance Societal Resilience to Environmental
Changes” [11].
4. Conclusion
The latest information on the efforts of NTT Space
Environment and Energy Laboratories were explainedin this article. The Feature Articles in this issue will
discuss some of the themes that have achieved success. We hope you will keep abreast of the growth of
the Laboratories as it takes on the challenge of creating innovative technologies in the environment andenergy field from a space perspective.

47

Feature Articles

References
[1]
[2]
[3]

[4]
[5]

[6]

Beyond Our Planet (in Japanese), https://www.rd.ntt/se/media/
Press release issued by NTT on Nov. 21, 2023 (in Japanese). https://group.ntt/jp/newsrelease/2023/11/21/231121b.html
N. Ochiai, Y. Suzuki, K. Kashiwakura, and Y. Toriumi, “Long-distance Laser-energy Transmission for Space Solar Power Systems andTheir Application on Earth,” NTT Technical Review, Vol. 22, No. 3,
pp. 56–63, Mar. 2024. https://ntt-review.jp/archive/ntttechnical.
php?contents=ntr202403fa6.html
Press release issued by NTT, “Identification of genes that dramatically improve carbon dioxide absorption in algae,” Feb. 9, 2023.
https://group.ntt/en/newsrelease/2023/02/09/230209c.html
Press release issued by NTT Green & Food, “Establishment of NTT
Green & Food, Inc.—A Joint Venture between NTT and Regional
Fish: Aiming to Create New Industries with Local Communities,”
June 27, 2023. https://www.ntt-green-and-food.com/en/information/
news/20230627/334/
M. Kozai, N. Hanaoka, H. Hasegawa, H. Takebe, S. Imamura, and T.
Tanaka, “Zero Environmental Impact Technology to Achieve a Clean
and Sustainable Society,” NTT Technical Review, Vol. 22, No. 3, pp.
49–55, Mar. 2024. https://ntt-review.jp/archive/ntttechnical.
php?contents=ntr202403fa5.html[7]

Press release issued by NTT on May 29, 2020 (in Japanese). https://group.ntt/jp/newsrelease/2020/05/29/200529a.html[8] Press release issued by NTT and OIST, “NTT and OIST Make theFirst Simultaneous Atmospheric and Marine Observations Directly
Beneath a Violent, Category 5 Typhoon in the North-West Pacific,”
May 23, 2023. https://group.ntt/en/newsrelease/2023/05/23/230523a.
html[9] Press release issued by NTT, “World’s first millimeter-wave RFID tag
to improve drone navigation accuracy—Aerial sensor network that
continues to operate even in poor visibility conditions such as night,
fog, and rain,” Oct. 2, 2023. https://group.ntt/en/newsrelease/2023/10/
02/231002a.html[10] H. Kawata, D. Tokunaga, and Y. Muto, “Forecasting Technologies forEnvironmental and Socioeconomic Cycles for Attaining Inclusive
Sustainability,” NTT Technical Review, Vol. 22, No. 3, pp. 70–74,
Mar. 2024. https://ntt-review.jp/archive/ntttechnical.php?
contents=ntr202403fa8.html[11] H. Iwashita, M. Hisada, M. Takahashi, and A. Miyajima, “Forefront
Research Initiatives on Environmental Adaptation to Enhance Societal Resilience to Environmental Changes,” NTT Technical Review,Vol. 22, No. 3, pp. 64–69, Mar. 2024. https://ntt-review.jp/archive/
ntttechnical.php?contents=ntr202403fa7.html

Yuji Maeda

Vice President, Head of NTT Space Environment and Energy Laboratories.
He received a Ph.D. in systems information
science from Future University Hakodate, Hokkaido, in 2013. He joined NTT Telecommunication Networks Laboratories in 1991. He has been
engaged in managing projects related to generalemergency management such as those concerning natural disaster response and cybersecurity.
He received the Scholarship Encouragement
Award from the Institute of Electronics, Information and Communication Engineers (IEICE) in1998. He is a senior member of IEICE and amember of the Institute of Electrical and Electronics Engineers (IEEE).

NTT Technical Review

Vol. 22 No. 3 Mar. 2024

48

Feature Articles: Efforts in the Environmental and Energy
Sector to Create a Sustainable and Resilient Society

Zero Environmental Impact
Technology to Achieve a Clean andSustainable Society
Masaki Kozai, Naoki Hanaoka, Hazuki Hasegawa,
Hiroaki Takebe, Sousuke Imamura, and Toru Tanaka
Abstract

To contribute to achieving zero environmental impact, NTT Space Environment and Energy Laboratories is engaged in research and development of new forms of energy, efficient and resilient energy
transport, and effective absorption and conversion of carbon dioxide (CO2). This article introduces virtual energy demand/supply control technology that makes the most effective use of renewable energy,
next-generation energy supply technology that uses a direct current (DC) grid using reliable DC power
supply, and oceanic CO2 reduction technology that uses the ocean food chain, which will all contributeto achieving carbon neutrality.
Keywords: zero environmental impact, sustainable, carbon neutral

1. Virtual energy demand/supply
control technology
Virtual energy demand/supply control technology(Fig. 1) is used to enable local production and consumption of renewable energy by adjusting power
consumption through appropriately arranging workloads to be processed using information and communication technology (ICT) equipment installed in
NTT telecommunications buildings distributed
throughout Japan across time and space. In cooperation with NTT Network Service Systems Laboratories and the NTT Network Innovation Center, thistechnology is being established and tested [1].This
technology consists of many elemental technologies,
such as forecast of renewable energy generation,
electricity-demand forecasts per building and per
workload, and various forecasts related to ICT
resources, optimization of energy demand and workload deployment based on the forecasts, and workload control technology to obtain the optimization
result. We have verified the functionality of newly
developed elemental technologies at a single site. To
NTT Technical Review

Vol. 22 No. 3 Mar. 2024

verify the effectiveness of this technology, we constructed a verification environment in fiscal year
2022 in which two sites approximately 1 km apart areconnected by a 10-Gbit/s line.
We defined the workload as the central processing
unit (CPU) and memory load applied to nine virtual
machines (VMs) that provide a virtual desktop service. These workloads were moved between sites
while service was running (live migration), and theevaluation was carried out in terms of energy, services, and operations.
Through experiments, we quantitatively determined the relationship between load conditions, thetime taken to move workloads, and adjustable power
consumption. For example, when all VMs are underheavy load (CPU usage 85%, memory usage 80%),
107 W of power consumption can be adjusted, which
is about 35% of the server power consumption (270
W). Note that it took approximately 90 seconds fromthe start of the VM move to its completion, and during that time, there was almost no effect on the virtual desktop service from the user’s perspective(Fig. 2).
49

Feature Articles

Fig. 1. Virtual energy demand/supply control and DC grid.

Fig. 2. Example of how power consumption changes over time when moving workloads.

This verification was conducted on two servers. By
applying this technology to a large number of servers,
power consumption may be adjustable on a large
scale by moving workloads. In the future, we will
examine feasibility by moving workloads over longer
distances and at multiple sites. We will also examine
the scalability of each elemental technology in parallel.

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Vol. 22 No. 3 Mar. 2024

2. Next-generation energy supply technology
Next-generation energy supply technology uses
safe and reliable direct current (DC) power feeding
technology to enable effective use of renewableenergy and flexible power interchange without power
failure even in times of disaster.
The severity of natural disasters has been increasing, and the resilience of new forms of power interchange urgently needs to be improved for preserving
50

Feature Articles(a) When using fuses to protect against short circuits(overcurrent protection cannot be coordinated)(b) When providing short circuit protection with a bidirectional
SCCB (overcurrent coordination can be achieved)

Fig. 3. System configuration and short-circuit protection of bus-wired outdoor DC power supply system.

the global environment and improving energy selfsufficiency.
To solve this problem, we are researching anddeveloping an outdoor DC power feeding system for
DC microgrids (Fig. 1). A feature of this system is its
reliability because the storage battery is directly connected to the power line and the power feeding system does not require electronic components that may
fail. By taking advantage of its reliability, we are
studying a system that connects a telecommunications building with storage batteries and multiple
customers with renewable energy via power lines andthat uses 380 VDC to provide power in both directions, focusing on electrical safety. In the first step inthis study, we verified the basic characteristics andsafety of electric power supply in a star wiring systemthat connects a telecommunications building to eachcustomer on a one-to-one basis [1]. For the next step,
we are studying a bus wiring system.
While bus wiring is more economical than star wiring in terms of the cost of laying power lines, if ashort circuit (the positive and negative power lines
come into contact) occurs at a certain point, a large
current may flow through the entire system, causing
power failure. For example, if a fuse is simply inserted to protect a short circuit in the bus wiring shown in
Fig. 3(a), a power failure will occur in the bus wiring.
Because the direction of the short-circuit current
through the bus wiring changes depending on the
short-circuit point, the current at short-circuit point B(green arrow) can be blocked by the nearest fuse (ii)to the short-circuit point, but the current at short-circuit point A (red arrow) can be blocked due to themalfunction of a fuse other than the nearest fuse (i) to
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Vol. 22 No. 3 Mar. 2024

the short-circuit point. Therefore, overcurrent protection coordination*1 between fuses cannot be achieved,
and multiple fuses may operate simultaneously,
resulting in the system shutting down. Even if thedirection of the short-circuit current changes, the circuit breakers need to cooperate to protect against theovercurrent and maintain the power supply of theusers other than the short-circuit point.
To solve this problem, we installed one bidirectional semiconductor circuit breaker (SCCB) at eachtrunk line and branch line of the bus wiring, which
can set the overcurrent-cutoff threshold for eachdirection of current, and clarified the conditions forthis threshold.
As shown in Fig. 3(b), a bidirectional SCCB is
installed in the bus wiring, and the overcurrent-cutoff
threshold is set to gradually decrease in the directionof power supply from one customer to another. Eachbidirectional SCCB consists of unidirectional SCCBs
connected in series in the opposite direction and features an overcurrent-cutoff threshold for each current
direction. As shown in Fig. 3(b), when there is a shortcircuit at point B, only SCCB (ii) operates quickly
and disconnects the short-circuit point. This isbecause SCCB (ii) has the smallest overcurrent-cutoff threshold in the direction of the short-circuit current and is the SCCB closest to the short-circuit point.
*1 Overcurrent protection coordination: Mutual adjustment (coordination) by intentionally creating differences in operating values​​
and times of multiple protection devices. This makes it possible
to detect fault currents such as short circuits and disconnect only
the fault section, thus avoiding power outages in other healthy
circuits. Regarding fuses, the operating value (fusing characteristics) cannot be changed depending on the direction of current, so
fuses can only coordinate for current in one direction.

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Fig. 4. Overview of CO2 reduction in the ocean using the marine food chain.

Similarly, when a short circuit occurs at point A,
SCCB (i), the closest to the short circuit, disconnects
it. In this case, only the SCCB close to the short-circuit point operates at the other points C, D, E, X, Y,
and Z as well, and the short-circuit point is disconnected. Therefore, when a short circuit occurs at any
point in the bus wiring, only the SCCB immediately
adjacent to the short-circuit point is shut off. This
minimizes the area affected by the power failure during the short circuit and improves the reliability of thebus-wiring power feeding system.
In the future, we will research and develop a systemthat does not lose power during a short circuit evenwhen the trunk line is a loop-wiring type. We will
also contribute to enabling flexible, safe, and secure
power feeding by further improving the reliability ofthe power feeding system.
3. Marine-food-chain-based CO2 reduction
technology in the ocean and its applications
Global warming has become a serious international
issue. Since carbon dioxide (CO2) in the atmosphereis considered to cause global warming, the need toreduce CO2 in the atmosphere is urgent. According to
the 6th Assessment Report by the Intergovernmental
Panel on Climate Change (IPCC), the ocean accounts
for 35.1% of CO2 absorption. The amount of CO2
absorbed by the ocean mainly depends on the concenNTT Technical Review

Vol. 22 No. 3 Mar. 2024

tration of CO2 dissolved in seawater. Therefore, it isexpected that if CO2 in the ocean is decreased, theamount of CO2 absorbed from the atmosphere to theocean will increase, which will lead to a decrease in
CO2 in the atmosphere.
In the ocean, algae*2 fix CO2 through photosynthesis*3. Fixing refers to the process of converting CO2
into organic compounds and incorporating it into living organisms. These algae are then directly or indirectly preyed upon by fish and shellfish in the foodchain, eventually leading to the fixation of carbon
within the bodies of the fish and shellfish. NTT is
currently focusing on this carbon fixation process
through the marine food chain to decrease CO2 inoceans (Fig. 4). Specifically, NTT aims to enhanceboth the carbon fixation ability of algae and the feeding/growth abilities of fish and shellfish by using
gene modification technologies such as genome editing*4. NTT also aims to optimize cultivation conditions to maximize and prolong the total amount ofcarbon fixed throughout the marine food chain. It isbelieved this research targeting algae as well as fishand shellfish can solve the problem of short-term*2 Algae: Organisms that photosynthesize, excluding land plants.
*3 Photosynthesis: In plants and algae, a reaction system that synthesizes organic matter from CO2 using light energy.
*4 Genome editing: A technology that specifically modifies any
base sequence on the genome. Unlike genetic recombination
technology, foreign genes do not remain within the cell.

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Fig. 5. T he schematic model of evaluation method of gene function and the evaluation results of 12 single-gene-modified
strains.

carbon fixation faced by traditional algae-related
studies. NTT, in collaboration with Regional Fish
Institute (RFI), a pioneer in fish-species improvement using genome editing technology, is advancing
research towards synergistically reducing CO2 inoceans by using the marine food chain. NTT is striving to improve the carbon fixation capability of algae;
working on selecting target genes, and developing
and evaluating productive strains by applying
genome editing technologies.
While the carbon fixation mechanism of algae haslong been studied, the genes involved in carbon fixation have not been fully clarified. Therefore, we first
selected genes expected to enhance carbon fixation
capacity. One method for evaluating gene function is
to observe the proliferation of a single-gene-modified
strain under specific conditions. For instance, since
the activity of photosynthesis generally decreases in
low CO2 environments, the growth of algae slows
when cultured under such conditions. If an algal
strain, modified by removing a certain gene A, proliferates significantly more under low CO2 conditions
than the unmodified strain, gene A may function to
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Vol. 22 No. 3 Mar. 2024

inhibit carbon fixation under low CO2 conditions (topof Fig. 5). If genome editing technology is applied togene A, a resultant algal strain will likely show
improved carbon fixation ability under low CO2 conditions.
At NTT, we applied the aforementioned gene function evaluation method and narrowed down the genes
involved in carbon fixation by varying the CO2 concentration during cultivation. We first obtained
genetically modified strains for each of the 12 candidate target genes then evaluated the proliferation ofthese strains. We found that genetically modified
strains related to two types of genes (genes 4 and 8)
proliferated significantly more than the unmodified
strains (bottom of Fig. 5). This greater proliferationsuggests that more CO2 is being absorbed and fixed
per unit time. In other words, the application of
genome editing to genes 4 and 8 may dramaticallyincrease the amount of CO2 absorbed by algae. On
the basis of the discovery of genes 4 and 8, we aim tobreed algae strains with improved carbon fixation
capabilities. Moreover, by identifying more target
genes and applying genome editing technology, we
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are committed to not only breeding strains with highcarbon fixation abilities, such as photosynthetic
activity, but also breeding strains that have industrial
benefits, such as the accumulation of useful substances.
To implement this research in the real world, NTT
Group, using useful algae breeding technology andtelecommunication technology, along with RFI’s
state-of-the-art shellfish-species-improvement andaquaculture technologies, established a joint venturecompany, NTT Green & Food (G&F) on July 1, 2023[2]. In accordance with the philosophy of “Making
the most of nature’s bounty with technology anddesigning the future of the earth and food,” G&F
aims to develop the Green & Food business composed of three axes: (i) production and sale of environmentally friendly algae, (ii) production and sale of

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environmentally friendly fish and shellfish that feedon these algae, and (iii) provision of a circular landbased aquaculture platform using these algae andshellfish. NTT will continue to advance technology
for breeding and producing useful algae toward theestablishment of the Green & Food business.
References
[1]

[2]

T. Tanaka, H. Minami, T. Tanaka, N. Nakamura, T. Hayashi, M.
Kozai, Y. Higuchi, N. Hanaoka, and M. Iwamoto, “Energy-distribution Platform Technologies toward Zero Environmental Impact,”
NTT Technical Review, Vol. 19, No. 6, pp. 22–29, June 2021. https://doi.org/10.53829/ntr202106fa3
Press release issued by NTT Green & Food, “Establishment of NTT
Green & Food, Inc. – A Joint Venture between NTT and Regional
Fish: Aiming to Create New Industries with Local Communities,”
June 27, 2023. https://www.ntt-green-and-food.com/en/information/
news/20230627/334/

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Feature Articles

Masaki Kozai

Hiroaki Takebe

Senior Research Engineer, Energy Network
Technology Group, Zero Environmental Impact
Research Project, NTT Space Environment andEnergy Laboratories.
He received a Ph.D. in engineering from Tokyo
Institute of Technology in 2010 and joined NTT
the same year. His research interests are energy
demand forecast and energy control technologies.

Researcher, Sustainable System Group, Zero
Environmental Impact Research Project, NTT
Space Environment and Energy Laboratories.
He received a Ph.D. from Kyoto University in
2023 and joined NTT Space Environment andEnergy Laboratories in April that year.

Naoki Hanaoka

Sousuke Imamura

Senior Research Engineer, Energy Network
Technology Group, Zero Environmental Impact
Research Project, NTT Space Environment andEnergy Laboratories.
He received an M.S. in particle and astrophysical science from Nagoya University, Aichi, in
2012. He joined NTT the same year, where hestudied 380 VDC power feeding systems. From2015 to 2019, he was a researcher at NTT
FACILITIES, where he studied oscillations in
power feeding systems and developed 380 VDCequipment. He is currently researching the electrical safety of DC micro grid. He is a member of
the Institute of Electronics, Information andCommunication Engineers (IEICE), the Instituteof Electrical Engineers of Japan (IEEJ), and theInstitution of Professional Engineers, Japan(IPEJ).

Hazuki Hasegawa

Researcher, Sustainable System Group, Zero
Environmental Impact Research Project, NTT
Space Environment and Energy Laboratories.
She was a Japan Society of Promotion of Science (JSPS) Research Fellow (Doctoral Course
1) from 2020 to 2023. She received a Ph.D. from
Tokyo Institute of Technology in 2023 and joined
NTT Space Environment and Energy Laboratories in April that year.

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Vol. 22 No. 3 Mar. 2024

Distinguished Researcher, Sustainable System
Group, Zero Environmental Impact Research
Project, NTT Space Environment and Energy
Laboratories.
He received a Ph.D. from Tokyo University ofAgriculture and Technology in 2005, was a JSPS
Research Fellow at the University of Tokyo from2005 to 2009, and joined Chuo University as an
assistant professor in 2009. In 2012, he wasappointed as an associate professor at Tokyo
Institute of Technology and was a visiting professor at Institute for Plant Biochemistry, HeinrichHeine-University Düsseldorf in 2019. In March
2021, he joined NTT Space Environment andEnergy Laboratories as a distinguished researcher. He has received prestigious awards from theSociety of Genome Microbiology, Japan, in 2010
and Nagase Science and Technology Foundationin 2017. He is a member of the Japan Society for
Bioscience, Biotechnology, and Agrochemistry,
the Japanese Society of Plant Physiologists, theSociety of Genome Microbiology, Japan, and theJapanese Society of Photosynthesis Research.
His research interests include regeneration of the
global environment using photosynthetic organisms, especially algae, with molecular biology
approaches.

Toru Tanaka

Senior Research Engineer, Supervisor, Zero
Environment Impact Research Project, NTT
Space Environment and Energy Laboratories.
He received a B.E. and M.E. in quantum science and energy engineering from Tohoku University, Miyagi, in 1996 and 1998. He joined
NTT Integrated Information and Energy Systems
Laboratories in 1998, where he developed
HVDC power supply systems for telecommunication buildings and datacenters. From 2009 to
2012, he was a manager at NTT FACILITIES,
where he developed power supply systems andsmart community. He received the 2003 and2009 Shibusawa Award of the Japan Electric
Association (JEA). He is Professional Engineer,
Japan (Electrical & Electronics Engineering). He
is a member of IEICE.

55

Feature Articles: Efforts in the Environmental and Energy
Sector to Create a Sustainable and Resilient SocietyLong-distance Laser-energy
Transmission for Space Solar Power
Systems and Their Application on
Earth
Natsuha Ochiai, Yukiko Suzuki, Kazuto Kashiwakura,
and Yohei Toriumi
Abstract

NTT Space Environment and Energy Laboratories is researching space solar power systems (SSPSs)
to enable clean and sustainable next-generation energy. In this article, we explain what an SSPS is andintroduce the issues and efforts regarding energy-transmission technology involving lasers, technology
to convert sunlight into laser light, and technology to efficiently convert laser light into electric power.
Keywords: space solar power system, optical wireless power transmission, laser

1. What is a space solar power system?
A space solar power system (SSPS) is a next-generation energy technology that converts solar energy
into laser light or microwaves on a geostationary
satellite orbiting the Earth, transmits it to the ground,and uses it as power. Since the orbit of a geostationary
satellite is 36,000 km above the Earth’s surface, thesatellite rarely enters the Earth’s shadow, and unlike
conventional solar-power generation, it can generate
electricity day and night. Because there is no scattering or absorption by clouds or the atmosphere inspace, the energy per unit area of sunlight is expected
to be about 10 times that of the ground per year. An
SSPS has been attracting attention as a clean andlarge-scale energy technology using solar energy,
regarded as inexhaustible in unobstructed space.
Microwave and laser have been proposed as media
for transmitting energy from space to the ground.
NTT is researching SSPSs using lasers, which have asmaller beam divergence than microwaves andexpected to enable system-size reduction. A schematic of this SSPS is shown in Fig. 1. First, solar
energy is converted to laser light on a geostationary
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satellite and transmitted to the ground for 36,000 km.
The laser light is then converted to electric power byusing photovoltaic devices*1 such as solar cells at alight-receiving facility on the ground. Chemical raw
materials such as hydrogen can also conceivably begenerated using the energy of laser light on the
ground.
We present the challenges and initiatives of thelaser-energy-transmission technology necessary for
SSPSs. We also describe the research status of technology for solar-pumped lasers and high-intensity
beam-energy conversion and introduce examples ofthese technologies being deployed on the ground.
2. Laser-energy-transmission technology
2.1 Diffraction and atmospheric turbulence
In an SSPS, laser light is propagated from a*1 Photovoltaic device: A semiconductor device that converts lightinto electricity. Semiconductors generate electromotive force
when light is shone on them due to the photoelectric effect. Bychanging the composition of the semiconductor, the wavelengthof light that can efficiently generate electromotive force can bechanged. Solar cells are also a type of photovoltaic cell.

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Atmosphere

Sunlight  Laser light

wavefront

Laser

eddy
Spatial transmission
36,000 km(Geostationary satellite)

Fig. 2. C onceptual diagram of beam propagation in theatmosphere.

1st plane(Input)i th plane

i +1th planen th plane(Output)

Laser light Electricity, hydrogen, etc.

Fig. 1. Schematic of laser-SSPS.

geostationary satellite to the ground over a distanceof 36,000 km. Laser light diffracts, causing beam
divergence as it propagates. Since a typical Gaussian
beam*2 tends to diverge more the thinner it is, thebeam needs to be widened to reduce the beam-divergence angle for long-distance transmission. For
example, a beam with a diameter of 1 cm will spread
to about 1 km when propagated over 36,000 km,
which would require a massive ground-based receiving facility. To suppress beam divergence, the beam
diameter of the transmitting side needs to be widened
to several meters.
The atmosphere from the surface of the Earth up to
about 100 km above contains eddies of various sizes,
as shown in Fig. 2, causing the refractive index of theatmosphere to change randomly in space and time.
When laser light propagates through the atmosphere,
the wavefront is disturbed by air eddies, resulting influctuations in the intensity distribution of the beam.
This is called atmospheric turbulence. If the intensity
distribution of the beam fluctuates, there will be a
reduction in power generation when converting laser
light into electricity with a light-receiving panel consisting of multiple photovoltaic cells, as the light is
not evenly projected on the panel [1]. Therefore, it isimportant to design a beam that is less affected byatmospheric turbulence and an optical system for thelight-receiving panel that matches the shape of the
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Fig. 3. S chematic of the model of split-step beampropagation method.

beam.
2.2 S
 imulation of beam propagation throughatmosphere
To predict the effect of diffraction and atmosphericturbulence on beam propagation, we conducted beam
propagation simulation in the atmosphere. The splitstep beam-propagation method effectively reproduces the propagation in a random medium such asatmospheric turbulence. With this method, the propagation is calculated by dividing the propagation optical path into multiple sections by using multiple
phase screens, as shown in Fig. 3. By reflecting therefractive-index distribution of the atmosphere inthese phase screens, the effect of atmospheric turbulence can be reproduced together with diffraction bynormal propagation. To generate a phase screen, we
need a spectrum model of the atmosphere. Commonly used models include the Kolmogorov spectrum, von Karman spectrum, and modified von Karman spectrum [2]. The Kolmogorov spectrum iswidely used as a basic model, but it lacks accuracy
because it does not take into account the size of air
eddies that affect the spatial frequency of atmospheric*2 Gaussian beam: One of the propagation modes of optical beams
in which the intensity distribution follows a Gaussian function.
The intensity decreases in accordance with a Gaussian function
as the position moves away from the center of the beam.

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Feature Articles(a) Propagation in vacuum(b) Propagation in atmosphere

Fig. 4. Gaussian-beam pattern after propagation.

fluctuations. The von Karman spectrum and modified
von Karman spectrum, however, can take into
account the minimum and maximum size of the air
vortex, respectively. In this simulation, the modified
von Karman spectrum was used as a spectrum model.
This spectrum uses the minimum (called inner scale)and maximum (called outer scale) magnitudes of air
eddies as well as a parameter called the atmosphericrefractive index structure constant, which represents
the strength of the refractive-index change. Typicalvalues of the inner scale are on the order of 1 to 10
mm near the ground surface, and the outer scale usually decreases in proportion to the altitude in the area
up to 100 m from the ground [2]. The atmosphericrefractive index structure constant usually ranges
from 10–17 to 10–13 m–2/3, depending on the season
and time. These parameters are assigned to the modified von Karman spectrum, and a phase screen is
generated using Fourier transform [3]. Figure 4
shows the beam pattern after atmospheric propagation of the Gaussian beam obtained through simulation (the parameters used in the calculation are listed
in Table 1). By propagating through the atmosphere,
the intensity distribution of the beam is finely disturbed.
2.3 Experiment
In an SSPS, laser light is irradiated from a geostationary satellite to the ground to transmit energy, so
the transmission direction is vertical to the ground.
However, in the vertical direction, it is difficult toensure the safety of laser light and arrange appropriate test sites. Therefore, we first conducted an energytransmission experiment in the horizontal direction
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Table 1. Calculation parameters.
Wavelength1064 nmBeam width (full width at
1/e2 maximum)

60 mm

Wavefront curvature radius

250 m

Propagation distance

1 km

Inner scale

1 mm

Outer scale

1m

Atmospheric refractive
index structure constant
Number of phase screens
Number of pixels
Pixel pitch

10−13 m−2/3
214084 × 4084
0.1 mmon the ground in collaboration with Mitsubishi Heavy
Industries, Ltd to verify the beam-propagation simulation in the atmosphere and examine the energyconversion efficiency [4, 5]. In addition to the Gaussian beam with a laser wavelength of 1064 nm, a special beam called the Laguerre-Gaussian (LG) beam*3
was prepared to transmit 1 km in free space and irradiate a 400 mm × 400 mm light-receiving panel (Fig. 5).
For long-distance and high-power beam propagation,
the effect of aberration*4 of optical elements, such as
lenses, and thermal lens effect*5 become problematic.
In this experiment, the optical system of both Gaussian and LG beams was designed and adjusted to be*3 LG beam: A beam with a different intensity distribution from a
Gaussian one, forming a ring shape. As a beam with orbital angular momentum, it is attracting attention in various fields such as
light communication.

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Transmitter side
PV panelBeam width:
60 mm
M4

1-km
propagation

BE

BB1
BS

M3
DOE

er

M2

M1

Las

m
Bea :
h
widt m
BB2 15 m

M1-M3: mirrors M4: direction-control mirror BB1, BB2: beam blocks
BS: beam splitter BE: beam expander DOE: diffraction optical element
PV: photovoltaic

Fig. 5. Schematic of optical system of energy transmission [5].

(a)

(b)

(a) Gaussian beam and (b) LG beam captured during the experiment
(c)

(d)

(c) Gaussian beam and (d) LG beam calculated through the simulation
Scale bar (yellow line): 100 mm

Fig. 6. Beam pattern after 1-km propagation [5].

about 300 mm when irradiated to the light-receiving
panel [3], and a large-diameter lens and low-aberration expander were prepared to prevent aberration. To
verify the atmospheric-turbulence simulation, thebeam pattern was captured with an infrared camera
for 1 min and the intensity distribution was obtained.
To examine the transmission efficiency, the power
extracted from the light-receiving panel was measured through current-voltage (IV) measurement*6.
Figure 6 shows the experimental and simulation
results of the beam pattern after 1-km transmission.
In the simulation, the atmospheric structure constantmeasured during the experiment is used, but thephase screen that reproduces the effect of the turbulence was randomly generated, so the results of theexperiment and simulation do not completely match.
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However, the beam’s shape is generally consistent,such as the size of the beam and disturbance of the*4 Aberration: Deviation from the ideal wavefront caused by distortions in optical components such as lenses and mirrors. In longdistance beam propagation, as in this article, the problem is thatthe beam divergence deviates from the ideal due to aberration,
especially spherical aberration, which shifts the focal position inaccordance with the distance from the optical axis.
*5 Thermal lens effect: A phenomenon in which the refractive index
of optical components, such as a lens, changes when strong laser
light is irradiated and that part is heated. Similar to aberration, it
poses a problem because it affects the beam divergence and intensity distribution.
*6 IV measurement: A method for evaluating the IV characteristics
of semiconductors, such as photovoltaic cells or diodes. By plotting current on the vertical axis and voltage on the horizontal
axis, one obtains an IV curve showing the power generation capability of the solar cell.

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ParabolicmirrorEquatorial
mount(a) Image of laser single-crystal rod

Laser rod/Resonator
mirrorOscillation
light(b) Solar incidence oscillation
evaluation system

Fig. 7. Solar-pumped laser-oscillation experiment.

intensity caused by the turbulence. When the beam
diameter was calculated from the integrated value ofthe acquired intensity distribution, the error between
the experiment and simulation was within 5% forboth Gaussian and LG beams [5]. The average valueof the center of gravity deviation of the beam calculated in each frame of the video showed an error of
2% between the experiment and simulation [5], indicating that the simulation could accurately reproduce
the disturbance in the experiment.
Next, IV measurements were conducted to calculate the energy conversion efficiency. The conversion
efficiency of the Gaussian beam and the LG beam
was as low as 3% [5]. As can be seen from Fig. 6, thisis thought to be due to the intensity distribution of thebeam being made non-uniform by atmospheric turbulence, and the light-receiving panel could not be
irradiated with uniform laser light. Therefore, a turbulence-robust transmission system is required, suchas a beam that can be uniformly irradiated even underatmospheric turbulences and a light-receiving panelthat is less affected by variations in the amount of
irradiation.
3. Other initiatives at NTT related to SSPSs
In addition to laser-energy transmission, we will
introduce the technologies that NTT is researching toenable an SSPS.
3.1 Solar-pumped laser
If a laser device is used as a light source for an
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SSPS, it is necessary to receive sunlight with a lightreceiving panel, convert it into electric power, andgenerate laser light using the electric power. However, this method involves many energy-conversion
processes, which may complicate the system. Therefore, NTT laboratories are studying solar-pumped
laser technology, in which solar light is directly irradiated to a laser medium for laser excitation. This
technology is expected to reduce the size and weightof the system. Codoped media, such as neodymium
and chromium-codoped yttrium aluminum garnet(Nd:Cr:YAG) and neodymium and cerium-codoped
YAG (Nd:Ce:YAG), which absorb the energy of sunlight in a wide wavelength spectrum and capable oflasing at a wavelength of 1064 nm, have been investigated as solar-pumped laser media. However, mostare made of ceramics, and high-quality single-crystal
media have not been reported. In consideration of thepossibility of application in space, where heat dissipation is difficult, NTT laboratories are researching
single-crystal laser media in collaboration with the
Graduate School for the Creation of New Photonics
Industries. Thus far, Nd:Cr:YAG single crystals and
Nd:Cr:Ce:YAG single crystals have been grown andprocessed into rod types for lasing (Fig. 7(a)). The
authors constructed a system for measuring laseroscillation intensity by concentrating sunlight onthese laser rods with a parabolic mirror and conducted an oscillation experiment outdoors [6] (Fig. 7(b)).
As a result of the oscillation experiment, laser
oscillation by solar-light injection was confirmed for
Nd:Cr:YAG and Nd:Cr:Ce:YAG single crystals.
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Power-conversion efficiency (%)

Feature Articles

Outer-ring electrodeMesh-shaped electrode

Incident laser power (mW)(a) Image of outer-ringelectrode device(b) Image of PV device
evaluation(c) Laser-power dependence ofpower-conversion efficiency

Fig. 8. Measurement-evaluation experiment of a prototype PV device [7].

However, compared with the ceramic medium of thesame material, both single crystals were below thecharacteristics of ceramics at the oscillation threshold*7 and slope efficiency*8. In the future, we will
analyze the mechanism of laser excitation occurringin a single-crystal medium and investigate a laser
medium that has higher oscillation efficiency andsuitable for an SSPS.
3.2 High-intensity beam-energy conversion
We are also researching photovoltaic devices thatcan convert high-intensity laser light from space into
electric power on the ground. As mentioned above, inan SSPS, energy of megawatt class is transmitted to
the ground with a beam diameter of several meters.
To use this energy as much as possible without waste,
we are developing a photovoltaic device with highefficiency and high output in collaboration with University of Miyazaki. An indium gallium arsenide
phosphide (InGaAsP) photovoltaic device with ahigh photoelectric conversion efficiency at a wavelength of 1064 nm, which is the assumed wavelengthof the laser, has been prototyped, and studies areunderway to improve the characteristics of photoelectric conversion and increase the device area.
Figure 8(a) shows a device for reducing electricalresistance with an outer-ring electrode. The device
was irradiated with 1064-nm laser light using themeasuring jig shown in Fig. 8(b), and the powerconversion efficiency was measured. The results areshown in Fig. 8(c). For comparison, the characteristics of a photovoltaic device with mesh-shaped electrodes without outer-ring electrodes are also plotted.
The power-conversion efficiency with outer-ringelectrodes is up to 27%, indicating that the resistance
NTT Technical Review

Vol. 22 No. 3 Mar. 2024of the conductor is reduced and the efficiency isimproved by using outer-ring electrodes [7]. We willfurther improve conversion efficiency by improving
the anti-reflection coating and electrode design.
When such a semiconductor photovoltaic device isused, however, the photoelectric-conversion efficiency is limited to about 50–60%, and the remainder
becomes heat. Therefore, we are also studying ways
to use laser energy efficiently in forms other thanelectricity, for example, by using laser energy as aheat source at extremely high temperatures to generate hydrogen and reduce carbon dioxide to produce
fuels and chemical raw materials.
4. Ground use
Although SSPSs are expected to be commercialized after 2050, we aim to make early contributions
to society by applying these elemental technologies
on the ground before SSPSs are fully implemented.
We believe that power can be supplied to areas suchas remote islands where cables are difficult to lay, ordisaster-stricken areas where the power grid has been
cut off. We are also considering the potential for
application to power supplies for mobile bodies such
*7 Oscillation threshold: The minimum incident light power atwhich oscillation occurs in an optically pumped solid-state laser.
If the injected current is small, the amplification of light falls
below the attenuation, and oscillation does not occur. As the current is increased, the amplification increases and oscillation is
initiated. The lower the oscillation threshold, the higher the performance of the laser.
*8 Slope efficiency: Beyond the lasing threshold, the laser output
increases proportionally to the incident light power. This rate ofincrease is called the slope efficiency. The higher the slope efficiency, the higher the performance of the laser.

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as drones and high altitude platform stations(HAPSs)*9, where miniaturization and weight reduction are key issues. Flight-time limitations and hassle
involved in power supply are also factors that restrict
applications. Therefore, if energy supply to mobile
bodies during flight is made possible with laserenergy-transmission technology, we will be able tominimize the amount of batteries that need to beinstalled and extend flight time, which suggests a
widening of application possibilities.
5. Future work
Toward developing and implementing SSPSs, wewill continue to advance the laser-energy-transmission technology, solar-pumped laser technology, andhigh-intensity beam-energy conversion technology
introduced in this article. Various other technologies
are also needed to develop SSPSs, including technology for controlling the attitude of geostationary satellites and accurately beam to ground receiving facilities, and heat-dissipation technology in the vacuumof space. While cooperating with other institutions,
we aim to mature these technologies and achieve asustainable society through SSPSs. We will also promote the early deployment of ground applications

such as wireless power-supply systems using laserenergy-transmission technology.
References
[1]
[2]
[3]
[4]

[5]

[6]

[7]

K. Jin and W. Zhou, “Wireless Laser Power Transmission: A Review
of Recent Progress,” IEEE Trans. Power Electron., Vol. 34, No. 4, pp.
3842–3859, 2019. https://doi.org/10.1109/TPEL.2018.2853156
L. C. Andrews and R. L. Phillips, “Laser Beam Propagation throughRandom Media, Second Edition,” SPIE Press Book, 2005.
J. D. Schmidt, “Numerical Simulation of Optical Wave Propagation
with Examples in MATLAB,” SPIE Press Book, 2010.
N. Ochiai, Y. Toriumi, Y. Suzuki, K. Kashiwakura, T. Tanaka, K.
Onda, K. Kawazoe, Y. Takeuchi, and Y. Tsumura, “Ground Experiments of Laser Energy Transmission Technology for Space Solar
Power Systems,” 67th Japan Society for Aeronautical and Space Sciences Symposium, Toyama, Japan, Oct. 2023 (in Japanese).
N. Ochiai, Y. Toriumi, Y. Suzuki, K. Kashiwakura, and T. Tanaka,“Optical Wireless Power Transmission for Space Solar Power Systems,” The 44th Annual Meeting of The Laser Society of Japan, Jan.
2024 (in Japanese).
Y. Suzuki, Y. Toriumi, N. Ochiai, T. Tanaka, K. Hasegawa, and T.
Motohiro, “Fabrication and Characterization System of Single-crystal
Solar-pumped Lasers for Space Solar Power Systems,” Reports on
Topical Meeting of the Laser Society of Japan RTM23, pp. 1–6, July
2023 (in Japanese).
M. Arai, A. Kushiyama, Y. Motomura, Y. Suzuki, N. Ochiai, Y. Toriumi, and K. Nishioka, “InGaAsP Photovoltaic Device with CircularOuter Electrode for 1.06-µm-range Optical Wireless and Fiber Power
Transmission,” Compound Semiconductor Week 2023 (CSW 2023),
FrA1-5, Jeju, Korea, May/June 2023.

*9 HAPS: A system that mounts communication equipment on aircraft or balloons flying at an altitude of more than 20 km above
the ground to provide communication infrastructure and otherservices.

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62

Feature Articles

Natsuha Ochiai

Kazuto Kashiwakura

Researcher, Next-Generation Energy Technology Group, NTT Space Environment and Energy
Laboratories.
She received a B.E. and M.E. in electricalengineering from The University of Tokyo in2019 and 2021. She joined NTT in 2021 and has
been studying laser-energy transmission todevelop an SSPS. She is a member of the Japan
Society of Applied Physics.

Research Engineer, Next-Generation Energy
Technology Group, NTT Space Environment andEnergy Laboratories.
He received a B.E. and M.E. in astrophysics
from Nagoya University, Aichi, in 2021 and 2023
and joined NTT in 2023. His research interests
include space exploration and satellite development.

Yukiko Suzuki

Yohei Toriumi

Research Engineer, Next-Generation Energy
Technology Group, NTT Space Environment andEnergy Laboratories.
She received a B.E. and M.E. in electrical andelectronics engineering from Waseda University,
Tokyo, in 2020 and 2022 and joined NTT in
2022. Her research interests include energy systems and laser applications. She has been
researching and developing solar-pumped lasers.

NTT Technical Review

Vol. 22 No. 3 Mar. 2024

Senior Research Engineer, Next-Generation
Energy Technology Group, NTT Space Environment and Energy Laboratories.
He received a B.E. and M.E. in electrical andelectronics engineering from Tokyo Institute ofTechnology in 2003 and 2005 and joined NTT in
2005. His research interests include energy systems and laser applications.

63

Feature Articles: Efforts in the Environmental and Energy
Sector to Create a Sustainable and Resilient Society

Forefront Research Initiatives on
Environmental Adaptation to
Enhance Societal Resilience toEnvironmental Changes
Hidenori Iwashita, Masaki Hisada, Madoka Takahashi,and Asami Miyajima
Abstract

NTT Space Environment and Energy Laboratories aims to create a resilient society that can respondflexibly to environmental changes by predicting patterns in the environment and human activities anddeveloping technologies for environmental adaptation. In this article, we introduce the latest topics ofresearch in cosmic-ray barrier technology and global environmental futures forecasting technology.
Keywords: cosmic ray, typhoon forecast, ocean ecosystem

1. Introduction
The Resilient Environmental Adaptation Research
Project at NTT Space Environment and Energy Laboratories has been promoting research toward a resilient society that can respond flexibly to future environmental changes. The resilient society we aim foris a world in which we can adapt to environmental
changes. We will not only be able to avoid or forestallthe damage to human society caused by natural phenomena but will also be able to take advantage ofnatural phenomena that have been regarded asscourges. In October 2023, our project welcomed a
new research group, the Environment and Socioeconomic Nexus Forecasting Technology Group.
Together with this research group, we are working toaccelerate research aimed at sustainable prosperity
for people and the global environment (comprehensive sustainability), which requires anticipating more
long-term and complex events and taking early
action.
The technological themes we are working on toachieve these goals can be roughly categorized into
the following two phases. The first is adapting to
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Vol. 22 No. 3 Mar. 2024

environmental changes to enable more proactive
measures in advance to be taken in response to
extreme natural phenomenon, and the second is predicting future environmental changes for the adaptation by taking into account the mutual effects of the
global environment and human activities. With
respect to these themes, we introduce the latest
research topics in cosmic-ray barrier technology andglobal environmental futures forecasting technology,
respectively.
2. Forefront research initiatives of cosmic-ray
barrier technology
This section introduces findings in cosmic-ray
research (solar flares and radiation from galaxies),
which is part of our ongoing research aimed at environmental adaptation to avoid or lessen damage
caused by natural phenomena. Sophisticated electronic devices support our lives in numerous ways,
but they increasingly fall victim to soft errors causedby cosmic rays. When cosmic rays, which rain downfrom space, collide with oxygen or nitrogen atoms in
the atmosphere, neutrons are generated. When64

Feature Articles

Fig. 1. Mechanism of soft error occurrence.

neutrons collide with a semiconductor in an electronic device, they can cause soft errors, a phenomenon in which the data stored in a semiconductor arechanged. Soft errors have the potential to negatively
impact social infrastructures, such as telecommunication failures (Fig. 1). In considering measures against
soft errors in electronic devices, it is important thatthe system design takes into account the frequency ofthe soft-error-induced failures of each device. The
frequency of soft-error-induced failures varies greatly depending on the energy of neutrons reaching thedevice. Therefore, it is critical to clarify the energy
dependence of the soft-error rate (SER)*1 (SER at different neutron energies).
NTT Space Environment and Energy Laboratories
and Hokkaido University have joined forces and successfully measured the semiconductor SER at continuously varying neutron energies in the low energy
range of 10 meV (milli-electron volt) to 1 MeV(mega-electron volt), a range which has not beenpreviously measured [1]. The findings revealed acomplete picture of the neutron energy dependence ofsemiconductor soft errors in conjunction with ourmeasurements in the high-energy region, which weresuccessful in 2020 (joint research between Hokkaido
University, Nagoya University, and NTT) (Fig. 2).
Taking countermeasures against soft errors is essential for electronic devices that support our current
social infrastructure. Clarifying the SER for different
neutron energies is of utmost importance for studying
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such countermeasures since the SER varies greatly
depending on neutron energy.
We measured soft errors caused by low-energy neutrons below 1 MeV using the time-of-flight methodwith a high-speed soft-error detector developed in2020. The time-of-flight method is a means of calculating the neutron speed and converting it to kinetic
energy by measuring the time taken for the neutron to
travel a certain distance. The experiment was conducted by connecting a high-speed soft-error detector
developed by NTT to the instrument for neutron
source characterization (neutron beamline for observation and research use (NOBORU)) installed at theMaterials and Life Science Experimental Facility of
the Japan Proton Accelerator Research Complex(J-PARC) (J-PARC Proposal No. 2022A0249). The
intensity of neutrons used for irradiation at this facility was evaluated by Hokkaido University using thegold foil activation method*2. The SER in a fieldprogrammable gate array (FPGA)*3 was measured forcontinuously varying energies with high resolution.
*1 SER: The probability at which one neutron causes a soft error ina unit area. In more technical terms, it is defined as a single-event
upset (SEU) cross section or sometimes as the probability at
which a soft error occurs within a unit time.
*2 Gold foil activation method: A method of calculating the numberof neutrons used for irradiation by measuring gamma rays fromradioactive Au-198 produced when gold foil is irradiated withneutrons.
*3 FPGA: A logic device with which the user can program a logic
circuit in the field.

65

Feature Articles

SER
SEU Cross Section [cm2 / Mbit]

10−7
10−8
10−9
10−10
10−11
10−12
10−13
10−14

10−8

10−7

10−6

10−5

10−4
10−3
10−2
Neutron energy [MeV]

10−1

100

101

102

103

Fig. 2. SER at different neutron energies measured in this study.

Condition that increases number of low-energy neutrons
High-energy neutrons(generated in the atmosphere by cosmic rays)
Water

Plastic

Neutrons are slowed(losing energy).
Low-energy neutrons

An acurate number of failures can be calculated.

Fig. 3. Process of thermal-neutron generation.

The data show that the SER tends to be lowest
around 0.1 MeV but increases as the energy decreases.
We assume that this is due to boron (boron 10), which
is present in trace amounts in semiconductors.
Among the low-energy neutrons, we determined that
the SER is higher with neutrons in the energy bandaround 25 meV (2.5 x 10–8 MeV), known as thermal
neutrons*4. These thermal neutrons are produced
when high-energy neutrons enter hydrogen-containing materials, such as water, plastics, and electronic
substrates, and lose their speed. Therefore, their number varies greatly depending on the surrounding environment (Fig. 3). For example, if semiconductors arecooled by water, the thermal neutron count is expected to increase significantly. Thus, the data obtained inthis study will make it possible to simulate the number of failures caused by soft errors, taking into
account the surrounding environments of electronic
devices, and to take measures appropriate for thisenergy region.
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With the data obtained in this study, we have clarified the characteristics of the occurrence rates of soft
errors caused by low-energy neutrons in cosmic rays.
The findings make it possible to more accurately calculate the rate of failures caused by soft errors, whichis the key to evaluating soft errors and studying countermeasures. Soft errors have the potential to cause
malfunctions in all electronic devices that containsemiconductors. Evaluating soft errors and countermeasures against them is crucial to a variety of industries and business fields, from current informationand communication technology equipment and transportation infrastructure to artificial intelligencebased automatic control and smart factories, which
are expected to become more ubiquitous.
Going forward, we hope to contribute to the*4 Thermal neutrons: Neutrons with an energy around 25 meV.
When neutrons are repeatedly scattered in a material, they arecalled thermal neutrons because, on average, they equal the thermal kinetic energy possessed by the atoms of that material.

66Feature Articles

construction of a safer and more secure social infrastructure by simulating the number of failures causedby soft errors, taking into account the surrounding
environments of electronic devices, and by studying
soft-error countermeasures appropriate for low-energy regions. In due course, we will apply the results ofour research to countermeasures in space against cosmic rays, thereby contributing to constructing theSpace Integrated Computing Network [2], and theadvancement of humankind in space.
3. Recent trends in global environmental futures
forecasting technology
To improve societal resilience, global environmental futures forecasting technology is needed to predict
and adapt to the changing environment as well as torestore the environment, which has been impacted byhuman activities [3]. Such technology is used tomodel and simulate physical phenomena, such as
climate and weather, as well as biological and chemical phenomena, such as ecosystems and carbon
cycles, on the basis of global-scale observations.
Through highly accurate prediction of extreme
weather events, such as typhoons and linear precipitation zones, as well as changes in marine ecosystems
caused by human activities in conjunction with climate change, more proactive response measures canbe taken. The following sections introduce the progress in typhoon observation toward improving theaccuracy of typhoon forecasting and marine ecosystem circulation forecasting technology toward clarifying the path to restore the environment.
4. Progress in typhoon observation forimproving forecasting accuracy
Typhoons, which can have a major impact on society, have been intensifying in strength and causing
more damage as a result of global warming and otherconsequences of climate change. To prepare fortyphoons more effectively, it is important to accurately predict the strength of typhoons at landfall as
early as possible. However, typhoon forecasts basedon the analysis of satellite images are limited in accuracy.
In 2021, in collaboration with the Okinawa Instituteof Science and Technology (OIST), NTT beganobserving the area directly beneath typhoons, whichcannot be observed by satellite, using a wave glider.
In the summer of 2022, we successfully conducted
the world’s first simultaneous marine and atmospherNTT Technical Review

Vol. 22 No. 3 Mar. 2024

OISTER

Seiuchi-san
11 kmfrom center

Fig. 4. Observation of No. 11, Hinnamnor/Henry.

ic measurements at multiple locations in the northwest Pacific Ocean directly beneath a Category 5
typhoon, which is the strongest class typhoon, before
it reached land [4]. In this experiment, Seiuchi-san,NTT’s autonomous wave glider for atmospheric andocean observations, came as close as 11 km from thecenter of the typhoon (Fig. 4) and was able to capture
rapid changes in pressure in the storm area (top of
Fig. 5). Compared with OIST’s OISTER, Seiuchi-sanmeasured a rapid decrease in sea-water temperature(approx. 2°C) closer to the center of the typhoon(middle of Fig. 5). Seiuchi-san also measured amaximum wave height of approximately 9 m (bottomof Fig. 5), providing information on the interaction
between the atmosphere and ocean directly under thetyphoon, which had not been available from satellite
observations.
In 2022, we started a joint research project with the
Typhoon Science and Technology Research Center(TRC) of Yokohama National University, a research
institute in Japan specializing in typhoon research, toimprove the accuracy of typhoon forecasting [5]. We
will continue to progress typhoon observation forreal-time typhoon data collection and aim to improve
the accuracy of typhoon forecasting by using theacquired atmospheric and oceanographic observation
data and incorporating them into the TRC’s typhoon
forecasting model.
5. Progress of marine ecosystem circulation
forecasting technology
The marine ecosystem circulation forecasting technology models the food chain and material cycle
processes of marine ecosystems and predicts theimpact of human activities on marine ecosystems in
67

Feature Articles

Seiuchi-san
OISTER

1040
1020
1000
980
960
940
920
33

Seiuchi-san
OISTER

32
31
30
29
28
27
10
9
8
7
6
5
4
3
2
1
0

Seiuchi-san

Significant wave
height [m]Water temperature [°C]

Air pressure [hPa]

1060

0:00

12:00
Aug. 31

0:00

12:00

0:00

Sept. 1

Fig. 5. Observation data: air pressure (top), water temperature (middle), significant wave height (bottom).

addition to the effects of climate change [2]. This
technology contributes to the maintenance of ecosystem services such as the protection of fisheries
resources and carbon dioxide fixation.
As a first step, we developed an ecosystem model
for closed-cycle land-based aquaculture to predictchanges in the ecosystem. We first hypothesized theimpact of human activities on marine ecosystems on
the effluent from closed-cycle land-based oyster
aquaculture. We then developed a material circulation process model for oyster aquaculture, considering the simple food chain between oysters and phytoplankton, which is their diet.
Closed-cycle land-based aquaculture is a method of
aquaculture carried out in a closed space on land
without contact with rivers or the ocean. The water
quality is maintained by removing food and excreted
waste while circulating the water. In addition to oysters, phytoplankton (algae) are produced in the landbased oyster farm targeted in this study, and wastewater from the oyster tank is used to cultivate the algae,
thus achieving completely closed land-based aqua-

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Vol. 22 No. 3 Mar. 2024

culture without wastewater. Oyster cultivation is not
simply a matter of increasing the amount of phytoplankton. Undigested feed left by oysters can lead towater contamination, which affects oyster growth.
For efficient recirculation in land-based aquaculture,
it is important to determine the balance of circulation,
including the optimal amount of oyster excreta andfeed, which can be done by predictive simulation. We
developed a model for predicting changes in phytoplankton levels in recirculating land-based oyster
aquaculture (Fig. 6). The model was also used to
predict phytoplankton production from wastewater
discharged from oyster aquaculture.
In the future, we will extend the model and theknowledge obtained and apply it to modeling ecosystems in coastal areas where human activities have alarge and complex impact as well as in open ocean
areas that are expected to be increasingly used in the
future. We aim to develop a forecasting technology
for marine-ecosystem cycles that will help to restore
the ecosystems.

68Feature Articles

Algae

Feeding

Algal culture

Land-based oyster culture
CarbonBiogeochemical
cycle

Phosphorus

NitrogenAquaculture effluent

Feedback(residual feed and excreta)

Fig. 6. Biogeochemical cycle in land-based oyster farm.

References
[1]

[2]

[3]

H. Iwashita, R. Kiuchi, Y. Hiroshima, Y. Okugawa, T. Sebe, M.
Takeda, H. Sato, T. Kamiyama, M. Furusaka, and Y. Kiyanagi,“Energy-resolved SEU Cross Section from 10-meV to 800-MeV
Neutrons by Time-of-flight Measurement,” IEEE Trans. Nucl. Sci.,
Vol. 70, No. 3, pp. 216–221, 2023. https://doi.org/10.1109/
TNS.2023.3245142
Press release issued by NTT and SKY Perfect JSAT, “NTT and SKY
Perfect JSAT conclude collaboration agreement on new space enterprise to aid realization of a sustainable society,” May 20, 2021. https://group.ntt/en/newsrelease/2021/05/20/210520a.html
A. Koyama, X. Zhang, M. Hisada, and M. Hara, “Technology for

Hidenori Iwashita

[4]

[5]

Forecasting the Global Environment and Human Society,” NTT Technical Review, Vol. 21, No. 2, pp. 33–38, Feb. 2023. https://doi.
org/10.53829/ntr202302fa4
Press release issued by NTT and OIST, “NTT and OIST make theFirst Simultaneous Atmospheric and Marine Observations Directly
beneath a violent, Category 5 Typhoon in the North-West Pacific,”
May 23, 2023. https://group.ntt/en/newsrelease/2023/05/23/230523a.
html
Press release issued by NTT and Yokohama National University,“NTT and Yokohama National University Begin Joint Research
Aimed at Improving the Accuracy of Typhoon Forecasting—Helping
to mitigate the damage caused by typhoons to build a safer and moresecure society—, Jan. 25, 2023. https://group.ntt/en/newsrelease/2023/01/25/230125a.html

Madoka Takahashi

Senior Research Engineer, NTT Space Environment and Energy Laboratories.
He received a B.S. and M.S. in nuclear engineering from Hokkaido University in 2006 and2008. He has been researching soft errors since2012 at NTT Network Service Systems Laboratories and been engaged in research on techniques for mitigating soft errors in space at NTT
Space Environment and Energy Laboratories
since 2020.

Senior Manager of Planning Department andSenior Research Engineer of Global Environmental Futures Forecasting Technology Group,
NTT Space Environment and Energy Laboratories.
She received a B.S. and M.S. from Tokyo University of Science and MBA from Bond University, Australia. She has had a long career at thecentral research laboratory of a heavy industry
manufacturer and specializes in the space industry. She joined NTT in 2023 and has been
engaged in the Planning Department and Global
Environmental Futures Forecasting Technology
Group.

Masaki Hisada

Asami Miyajima

Senior Research Engineer, Supervisor, Global
Environmental Futures Forecasting Technology
Group, NTT Space Environment and Energy
Laboratories.
He received a B.A. from International Christian University, Tokyo, in 1999, and M.S. in
information science from Nara Institute of Science and Technology in 2001. Since joining NTT
in 2001, he led research on highly available inmemory database management systems andopen-source software development. In 2010, hejoined NTT Com Asia in Hong Kong as directorof the business development team. Since 2021,
he has been leading the Global Environmental
Futures Forecasting Technology Group.

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Vol. 22 No. 3 Mar. 2024

Executive Research Engineer, Resilient Environmental Adaptation Research Project, NTT
Space Environment and Energy Laboratories.
She received a B.E. and M.E. in science andtechnology from Keio University, Kanagawa, in1998 and 2000. She joined NTT in 2000, where
she was engaged in the development of medical
collaboration systems and research on cyberphysical security and behavior-change support.
Since 2023, she has been leading the Resilient
Environmental Adaptation Research Project.

69

Feature Articles: Efforts in the Environmental and Energy
Sector to Create a Sustainable and Resilient Society

Forecasting Technologies forEnvironmental and Socioeconomic
Cycles for Attaining Inclusive
Sustainability
Hiroaki Kawata, Daisuke Tokunaga, and Yuichi Muto
Abstract

The Environmental and Socioeconomic Nexus Forecasting Technology Group has been in the processof developing a computer-based circulation system consisting of several models (e.g. natural environment, economic, and social). We aim to forecast changes in global-scale inclusive cycles for inclusive
sustainability, in which the environment, economy, and society are interrelated and more stable. In thisarticle, we describe our developments for forecasting environmental impact considering the interplay
between the environment and economy and introduce a new index of affluence in the beyond GDP (grossdomestic product) era.
Keywords: climate and economic society, coupled simulation, inclusive wealth

1. Toward inclusive sustainability
The Environmental and Socioeconomic Nexus
Forecasting Technology Group has been researching
inclusive sustainability, which it defines as the sustainability made possible by the inclusive harmony
between the autonomy of the Earth’s environment
and the autonomy of economic and social systems
that are part of that environment [1].
The Earth’s environment has autonomy, and problematic environmental changes are a result of theinfluence of human economic and social activities on
this autonomy. This complex chain-reaction system
can be viewed as an inclusive cyclical system that
includes the environment, economy, and society on a
global scale. However, it is difficult to understand allof these interactions through observation and measurement in the real world. It is also difficult to evaluate their impact on the environment, economic
activities, and social activities due to implementation
costs, time delays in the occurrence of impact, andirreversibility of mutual influence.
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Vol. 22 No. 3 Mar. 2024

The goal of our group is to contribute to achieving
inclusive sustainability by reproducing the environment model, economic model, and social model as acyclical system on a computer, and making it possible
to calculate changes in inclusive cycles on a global
scale [2]. By being able to forecast changes in inclusive cycles using a computer, we hope to contributeto the global discussion on what social systems
should be and the transformations they need to undergo to get there. Toward this end, we have been developing a proof of concept of the cyclical system torealistically evaluate the relationship between thewater cycle and food production under the effects ofclimate change.
We introduce our research on forecasting the global
environmental impact considering the interplay
between the environment and the economy withregards to the global water cycle, as well as a newindex of affluence in the beyond gross domestic product (GDP) era using a new market-evaluation modelthat emphasizes human social activities.

70Feature Articles

2. Forecasting global environmental impact
considering the interplay between theenvironment and economy
2.1 C oupled simulation technology for inclusive
sustainability
To reproduce the complex systems of the environment, economy, and society on a computer more
precisely, we combine simulators developed by specialists in each of these fields.
Toward this end, it is necessary to exchange data
following the causal relationship between variables
in multiple simulators, and a method is needed tocontrol execution while exchanging data at the appropriate timing by managing the internal time of eachsimulator in a unified manner. Such coupling technology is called coupled simulation. We developed acoupled simulation technology [3] that requires minimal modification to existing simulators and can beapplied to various use cases.
2.2 G
 lobal-scale simulation considering the interaction between environmental and economic
activities with a focus on the water cycle
We conducted an experiment to determine if inclusive sustainability could be investigated in moredetail using the coupled simulation technology wedeveloped, observe the difference with and without
this technology, and verify its effectiveness. In thisexperiment, we focused on water, which is strongly
related to both environmental and economic activities, and constructed a global-scale simulation thattakes into account the interaction between environmental and economic activities, focusing on the
global water cycle [4].
To reproduce the global hydrological cycle, we use
the Integrated Land Simulator (ILS) developed by
Prof. Kei Yoshimura’s research team at the Instituteof Industrial Science of the University of Tokyo [5],which reproduces the surface-water-cycle process,and the Global Change Analysis Model (GCAM) [6],an integrated assessment model for economic activities developed by the Joint Global Change ResearchInstitute (JGCRI).
We hypothesized that changes in land-use patterns
due to economic activity would affect the hydrologic
cycle, which would then affect economic activity. To
verify this, the ILS and GCAM were coupled using
the coupled simulation technology to create a processthat takes into account the annual land-use patterns
due to changes in economic activity. The amount ofwater runoff calculated using the ILS and the amount
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Vol. 22 No. 3 Mar. 2024

of water consumption calculated using the GCAM
were then compared. Through this comparison andobservation of water-related changes in the environmental load (water stress*1) caused by changes in
economic activities over time, we showed that large
environmental loads can occur at times and places
that could not have been predicted with conventional
methods (Fig. 1).
We used one of the five Shared Socioeconomic
Pathways (SSPs)*2 (SSP126) and implemented a system in which two different simulators are linked toeach other to conduct global-scale calculations. For
the Niger River basin, for example, where many areas
are projected to change from grassland to cultivatedland between 2020 and 2044, it was found that water
stress tends to increase due to climate change.
Increased water stress is somewhat mitigated as landis converted to cropland. The results of this experiment indicate that the water stress of the Niger Riverbasin tends to increase with climate change [7] andthat linking different simulators is effective for calculating large-scale environmental changes.
2.3 Future developments
There are two major challenges in reproducing theinteractive effects of the environment and economic
activities while considering various policies. First,
simulating the environment requires excessive computations, so the amount of calculations needs to be
reduced (lightened) and the process should be coupled with other simulations. Second, current scientific calculations are based on scenarios of socioeconomic factors that assume changes in population,
economic growth, rate of technological development,
etc., making simulations based on other various
socioeconomic scenarios difficult. Therefore, we aim
to improve the accuracy of global-scale simulations
and increase the number of trials while reducing theamount of calculations for efficiency. Furthermore,
the combination of new models will enable a moredetailed analysis of the challenges of limiting temperature increase to within 1.5°C, as discussed by theIntergovernmental Panel on Climate Change (IPCC),
contributing to society’s continued sustainable economic development on a scientific basis.
*1 Water stress: An indicator for evaluating the degree of water demand-related stress. In our experiment, water stress was determined to have occurred when it exceeded 20%, calculatedmonthly and yearly as the water consumption/runoff (water
availability).
*2 SSPs: Five scenarios depicting how socioeconomic factors (population, economic growth, education, urbanization, rate of technological development, etc.) will change over the next 100 years.

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Feature Articles

AssumedclimateFuture climate
projections

Assumed economic activities

Shared Socio-economic Pathways (SSPs)

NTT• Coupled simulation
technology• Land use conversion
technology

UTokyoNTT & UTokyo
Global Change Analysis
Model (GCAM)

Integrated Land Simulator (ILS)

Water stress assessment

Fig. 1. Diagram of coupled simulation between the environment simulator and the economic activity simulator.

3. A new index of affluence in the beyond
GDP era3.1 BackgroundDue to the growing importance of environmental
measures for reducing carbon emissions, carbonemission trading measures such as carbon credits arebeing promoted at the national, regional, and local
levels. For such measures to be continuously operated and effective, they need to contribute to achieving
environmental goals and enrich society as a whole
while balancing environmental measures, the economy, and our daily lives. Our challenge is to develop
technologies to dynamically predict how the wealthof the world will change as a result of environmental
measures in the long term and evaluate the inclusive
sustainability of the environment, society, and economy.

are trying to measure is not limited to economic
wealth, such as material wealth, but also the wealth of
the natural environment and resources as well as
health and education. Indicators are needed to evaluate the overall wealth of the environment, people, andgoods.
The environment and society interact and behave as
a complex system. Therefore, social changes causedby one of the environmental measures may result in achain of unintended consequences, such as improved
forest conservation but accelerated consumption ofother resources, or slower-than-expected economic
growth. When considering environmental measures,
it is more important to determine the overall movement of a measure’s various implementations andpredict the general outlook than to reproduce andpredict the precise movements of the environmentand society over time.

3.2 C hallenges with dynamic long-term forecasting and assessment of the world’s overall
wealthIt is necessary to take a holistic view of the world’s
overall wealth, environment, and social trends to replicate general behavior that will take place in theenvironment and society of the future. The wealth we

3.3 Research approach
We focus on the inclusive wealth index (IWI) andsystem dynamics (SD) to address these challenges.
The IWI is for conducting a comprehensive wealthassessment. GDP is the most widely known indicatorof economic wealth. However, there is a growing
awareness of the importance of measuring the overall

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Feature Articles

Natural capital

Human capital

Product capital

Environment

WealthIndices for comprehensive capital assets
Inclusive Wealth Index (IWI)

Dynamic model forcomprehensive
wealth projection

Environmental
protection scenarios

Modeling with inclusive wealthPrimary projection models
Projection
modelsIncrease in IWI
by investment
Decrease in IWI
by production

IWI

Projecting the futureenvironment and society

Modeling technology suitable forcomplex systems
System Dynamics (SD)Climate change

Economic
activities

Investment
Influence
model

SD

Water

Sales
Production

Mutual interactions incomplex systems
HealthForestFig. 2. A conceptual model for projection of affluence in environmental social cycles combining IWI and SD.

wealth of the world, including the wealth of the environment and people. Since it is difficult to measure
wealth in terms of GDP, we have entered what is
known as the Beyond GDP era. Therefore, we focus
on the IWI, which is attracting attention internationally as an indicator for analyzing the comprehensive
wealth of a country or region and measuring andevaluating natural wealth (environment, resources,etc.), people (education, health, etc.), and artifacts(products, facilities, etc.) in the region. Whereas GDP
cannot assess resource depletion or health hazards,
the IWI directly assesses the value of nature andpeople, thus can be used to assess such impact.
Predictive models for the environment and society
are constructed using SD, a systems-thinking andmodeling method for complex systems. SD generates
numerical models by representing causal relationships among known elements in a graphical form. It
is suited for simple description and trend forecastingof complex systems, making it suitable for predicting
environmental policies.
Combining the IWI and SD, we examined the common structures between environmental social cycles
and affluence and modeled the impact of environmental measures on affluence (Fig. 2).

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3.4 Future developments
We are developing an IWI-based environment andsociety forecasting model to predict environmental
goals and affluence. We are currently in the processof validating the dynamic predictions made in thisresearch by creating a simulation model on emissions
trading in the carbon-credit market and evaluating its
contribution to improving the wealth of society as awhole.
References
[1]
[2]

[3]

[4]

[5]

NTT press release, “NTT announces new R&D projects of Digital
Twin Computing,” Nov. 13, 2020. https://group.ntt/en/
newsrelease/2020/11/13/201113c.html
M. Maruyoshi, Y. Muto, and D. Tokunaga, “Coupled Simulation
Technology for Visualizing Environmental and Economic Social
Cycles,” NTT Technical Review, Vol. 20, No. 3, pp. 31–35, Mar.
2022. https://doi.org/10.53829/ntr202203fa5
T. Fukuda and M. Maruyoshi, “Research and Development of Cosimulation Technology for Attaining Inclusive Sustainability,” NTT
Technical Review, Vol. 21, No. 4, pp. 38–42, Apr. 2023. https://doi.
org/10.53829/ntr202304fa5
Press release issued by NTT and the University of Tokyo, “A study on
long-term environmental impacts with global scale simulation considering the interaction between the natural environment and economic
activity—Aiming to achieve a global scale inclusive sustainability,”
May 25, 2023. https://group.ntt/en/newsrelease/2023/05/25/230525a.
html
T. Nitta, T. Arakawa, M. Hatono, A. Takeshima, and K. Yoshimura,“Development of Integrated Land Simulator,” Prog. Planet. Sci., Vol.
7, No. 68, 2020. https://doi.org/10.1186/s40645-020-00383-7

73

Feature Articles[6]

K. Calvin, P. Patel, L. Clarke, G. Asrar, B. Bond-Lamberty, R. Y. Cui,
A. Di Vittorio, K. Dorheim, J. Edmonds, C. Hartin, M. Hejazi, R.
Horowitz, G. Iyer, P. Kyle, S. Kim, R. Link, H. McJeon, S. J. Smith,
A. Snyder, S. Waldhoff, and M. Wise, “GCAM v5.1: Representing the
Linkages between Energy, Water, Land, Climate, and Economic Systems,” Geosci. Model Dev., Vol. 12, No. 2, pp. 677–698, 2019. https://Hiroaki Kawata

Senior Research Engineer, Supervisor, Resilient Environmental Adaptation Research Project,
NTT Space Environment and Energy Laboratories.
He received a B.E. and M.E. in electrical engineering from Hokkaido University in 2001 and2003 and joined NTT in 2003. Since 2023, he has
been leading the Environmental and Socioeconomic Nexus Forecasting Technology Group.
His research interests include remote collaboration system, user interfaces, and telepresencetechnologies. He is a member of the Institute ofElectronics, Information and Communication
Engineers (IEICE).

[7]

doi.org/10.5194/gmd-12-677-2019
K. Fushio, Y. Muto, T. Fukuda, Y. Tsukada, T. Nitta, T. Yoshikane, D.
Yamazaki, K. Yoshimura, and M. Maruyoshi, “Water Stress Evaluation by Coupled Simulation of Integrated Land Simulator (ILS) and
Integrated Assessment Model (IAM),” Production Research, Vol. 75,
No. 2, pp. 135–140, 2023.

Yuichi Muto

Senior Research Engineer, NTT Space Environment and Energy Laboratories.
He received a B.E. and M.S. in information
science from Tohoku University, Miyagi, in 1998
and 2000. He joined NTT in 2000 and wasengaged in research and development concerning
the Communication Traffic and Service Quality
Project at NTT Service Integration Laboratories.
He also researched and developed human flow
measurement and prediction technology using
Wi-Fi communication logs, which he worked on
as a business at a group company. Since 2023, hehas been researching coupled simulation between
environmental and economic activities at NTT
Space Environment and Energy Laboratories.

Daisuke Tokunaga

Senior Research Engineer, NTT Space Environment and Energy Laboratories.
He received an M.S. in information sciencefrom Kyushu Institute of Technology, Fukuoka,
in 1999 and joined NTT the same year. His
research interests include large-scale application
system technologies. Since 2023, he has been
researching coupled simulation between environmental and economic activities at NTT Space
Environment and Energy Laboratories.

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Vol. 22 No. 3 Mar. 2024

74

Regular Articles

Long-distance RDMA-acceleration
Frameworks
Hitoshi Masutani, Junki Ichikawa, Kiwami Inoue,
Tomoya Hibi, Kazuaki Obana, Takeshi Kugimoto,
Tsuyoshi Ogura, Koki Yube, Hirokazu Takahashi,
and Koichi Takasugi
Abstract

Most datacenter networks have adopted remote direct memory access (RDMA) as the basis of thetransport network to their infrastructure because modern RDMA network interface cards can provide
high-performance and energy-efficient capabilities to transfer data. Standard RDMA has been developed
for short-distance transmission such as internal datacenters for achieving high-performance computing.
We are currently developing the Innovative Optical and Wireless Network All-Photonics Network(IOWN APN) to achieve flexible, long-distance and low-latency optical-based networking for newgeneration use cases such as a cyber-physical system. By taking advantage of high-performance andlow-latency data transfer in RDMA over long-distance communication such as inter-datacenter networks
based on the APN, application-level networking should be accelerated over the IOWN APN. We propose
two long-distance RDMA-acceleration frameworks. We first present the RDMA over Open APN
framework to increase throughput of RDMA beyond 100 km by using the appropriate queue-pairconfiguration. This is easy to use without additional components. We then present the RDMA wide area
network (WAN) accelerator to build a new long-distance RDMA-transmission framework without
resource limitation of SmartNIC in the RDMA over Open APN framework. We also evaluate theperformance improvement of the RDMA WAN accelerator compared with standard RDMA. For
example, for data transfer of 512-byte messages, the RDMA WAN accelerator has about 35 times
performance improvement compared with standard RDMA.
Keywords: IOWN, RDMA, RoCEv2

1. Introduction
Datacenter applications have required high-performance and low-latency networks in addition to low
energy consumption. Although Transmission Control
Protocol/Internet Protocol (TCP/IP) technologies
have been developed for achieving high-performance
networking, it is well-known that TCP/IP stack suffers from high central processing unit (CPU) utilization [1] especially in high-bandwidth networks for
protocol processing, which leads to decreased CPU
cycles for application workloads. Packet processing
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on one CPU core also cannot fill 100-Gbit/s or more
network bandwidth [1]. InfiniBand/remote direct
memory access (RDMA) was originally developed forhigh-speed network interconnect for high-performancecomputing (HPC) to connect computers [2]. Since
most RDMA network interface cards (NICs) have an
RDMA hardware accelerator to offload packet processing functionality into them, they can save CPU
cycles for networking and achieve both low-latency
and high-performance networking [3]. RDMA overConverged Ethernet version 2 (RoCEv2) is currently
available in the Ethernet to achieve RDMA [2].
75Regular Articles

Today’s datacenter accommodates compute- anddata-intensive workloads such as artificial intelligence (AI) inferences. However, there is limitation of
space to deploy commercial off-the-shelf servers in
one datacenter. To run many compute- and dataintensive workloads, multiple heterogeneous computing resources deployed in geographically different
datacenters are necessary. Therefore, high-performance and low-latency data transmission for datacenter interconnect (DCI) is inevitable. We are currently developing the Innovative Optical and Wireless Network All-Photonics Network (IOWN APN)
[4] to achieve layer-1 transmission based on opticalfiber for high-bandwidth and ultra-low latency. In
addition to this infrastructure, we are aware of thenecessity for network acceleration in terms of application. Though RDMA is one candidate for this, it
can suffer from performance degradation caused bylong fat-pipe networks. A reliable connection (RC)transport mode in RDMA is the most common transmission mechanism. However, it contains an
acknowledgement (ACK) scheme without data loss.
With long-distance communication such as DCI, theACK scheme degrades performance.
This article proposes two RDMA-acceleration
frameworks for long-distance transmission. We firstpresent the RDMA over Open APN framework toincrease throughput of RDMA beyond 100 km byusing the appropriate DCI queue-pair (QP) configuration. This is easy to use without any additional
components. We suggested this framework to the
IOWN Global Forum [5, 6]. We then present the
RDMA wide area network (WAN) accelerator tobuild a new long-distance RDMA transmission
framework without resource limitation of SmartNICin the RDMA over Open APN framework. We also
evaluate the performance improvement of the RDMA
WAN accelerator by comparing it to standard RDMA.
For data transfer of 512-byte messages, the RDMA
WAN accelerator has about 35 times performance
improvement compared with standard RDMA.
2. RDMA
RDMA is a network-communication feature thatallows direct memory access (DMA) to a remote
server. RoCEv2 provides RDMA-capable networks
on the Ethernet infrastructure. For low-latency andhigh-performance data transmission, the RoCEv2
function is usually offloaded into a SmartNIC, which
has several acceleration hardware components forprimitive processing such as RoCEv2 protocol proNTT Technical Review

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cessing and cryptographic processing.
2.1 RDMA transports and verbs
When an RDMA local host (Local) communicateswith an RDMA remote host (Remote), there are threetransport modes including RC, unreliable connection(UC), and unreliable datagram (UD). Since RDMA
was originally developed for HPC and storage acceleration, which require reliability, RC is a common
transport mode. Almost all vendors implement RC in
SmartNICs as a default transport mode. In RC, QP is
an essential component to establish a connection
between Local and Remote and consists of sendqueue (SQ) and receive queue (RQ), each of which isa simple first-in-first-out queue. Since this QP is one
way, bi-directional communication requires at least
two QPs. Each SQ or RQ can accommodate as many
requests as an application can post into a SmartNIC
at once, which means sending memory data to
Remote or receive memory data from Remote. Such
requests are called work requests (WRs) and managed in each queue as a work queue element (WQE).
If an application posts one request as a WR into the
SQ, the WQE matching the WR is processed in the
SmartNIC to retrieve memory data from dynamic
random access memory on Local over the Peripheral
Component Interconnect (PCI) Express bus and build
one or more RoCEv2 packets by adding an RoCEv2
header to the memory data. After Remote receives the
RoCEv2 packet, the memory data conveyed in it aretransferred via the PCI Express bus to the memoryarea in Remote.
When Remote has successfully received the packet,
an ACK message is sent to Local. After receiving the
ACK message, Local releases the WQE to makeroom for the next WR. This is a basic operation in RC
and illustrated in Fig. 1.
2.2 Performance degradation in long-distancecommunication
When a long-distance network, such as DCI, isfrom several dozens to hundreds of kilometers, communication latency in an optical network reaches a
few milliseconds, as shown in Table 1. As the time
taken for the ACK message to arrive at Local is much
longer than the time taken for an application to post a
WR into a SmartNIC, the total available queue depth(QD) is easily exhausted. Therefore, WR posting isstalled, and the overall performance of RDMA in RC
may degrade. This is well-known in TCP as long fatpipe networks [7]. In TCP/IP communication, there
have been many proposals to address this issue
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Local

Remote
SQ

MemoryWQE

region

RQ

RDMA
Write

WQE

MemoryregionACK

WQE
Completion

Fig. 1. The basic operation flow in RC of RDMA.

Table 1. Network latency configuration for network emulation.
Communication
distance

One-way latency

Bi-directional latency(RTT)
100 µs

10 km

50 µs

100 km500 µs1 ms1000 km

5 ms

10 ms

[7–11]. We evaluated this impact of RDMA as a baseline performance in our experimental system inwhich the maximum line speed is 100 Gbit/s, as
shown in Fig. 2. Figure 3 shows our evaluation
results. In this evaluation, we ran the widely usedbenchmark tool perftest [12] to conduct basic
throughput tests. For 10-km communication, network
throughput dropped to 25.0 Gbit/s, and the throughput decreased to 3.0 Gbit/s at 100 km. We also
observed performance degradation to 0.3 Gbit/s for
1000-km communication.
3. Related work
The performance issue inherent in RDMA is close
to that of TCP. In long fat-pipe networks of TCP, thenetwork throughput depends on network latency
because a TCP client cannot send the next packet to a
TCP server until the TCP client finishes receiving the
ACK message. There are many types of algorithms toaddress this issue. In the loss-based algorithm, theamount of lost packets can start adjusting the congestion window (cwnd) to reduce network congestion
and improve network throughput [8–11]. In the
delay-based algorithm, round trip time (RTT) in a
TCP connection is used to change the cwnd on the
TCP client side to prevent network congestion. When
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Vol. 22 No. 3 Mar. 2024

RTT is small, the cwnd increases. However, the cwnd
decreases when RTT becomes larger.
Another approach to accelerate a TCP network is toput additional accelerators on both sides between the
TCP client and server. This is generally called TCP
WAN acceleration. In fact, the accelerator near the
TCP server monitors the status of a TCP connection,then the other accelerator on the TCP client produces
a pseudo-ACK message to immediately release the
TCP client waiting for the original ACK message.
4. RDMA over Open APN framework
4.1 Design
In the previous section, we described that adjusting
the TCP cwnd is a key factor of network performancefor sending packets continuously at once. In RDMA,
the amount of QD is related to the TCP cwnd. The QD
is configurable in certain SmartNICs such as NVIDIA
ConnectX series. To send packets without stalling
packet processing, we suggest the following formulafor QD configuration.
QD =RTT * Line Speed
Total Frame Size

Our experimental assumption is that the communication distance is from 10 to 1000 km, i.e., the RTT is77

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Server typeHardwarex86 server(Local, Remote)Network emulator

Specifications

CPUIntel Xeon Gold 6138 CPU 2.00GHz x 20 Core

MemoryDDR4 2666MHz 64GB ( 8 x 1GiB Hugepages )NIC (RDMA over Open APN)NVIDIA ConnectX-5 VPI

NIC (RDMA WAN accelerator)

NVIDIA ConnextX-6 DX

ChassisSpirent Attero-100G

Local

Network

100GbE RNIC
port0

Remoteemulator

port1

port0

100GbE RNIC

port1

port0

port1

RNIC: RDMA network interface card

Bit rate (Gbit/s)

Fig. 2. The experimental setup for evaluating RDMA throughput.

Transmission distance (km)Fig. 3. Impact of RDMA throughput based on communication distance.

from 100 μs to 10 ms. The line speed of the network
is 100 Gbit/s. For 100 km, an ideal QD is about 2991
when the total frame size is 4178. However, sincememory resources on a SmartNIC are limited, it isassumed that there should be an upper bound in theamount of configurable QD.
4.2 Performance evaluation
With our QD’s formula, we measure the network
throughput of RC in RDMA with 100-Gbit/s line
speed. Our experimental system in Fig. 2 has two
types of NICs. One is ConnextX-5 VPI and the otheris ConnectX-6 DX. In this measurement, we used
ConnectX-6 NIC. The QD of ConnectX-6 DX was
set to 16,384 and the Tx depth of perftest “ib_write_bw” was configured as 2048. The network emulator
between Local and Remote adds 500 μs latency one
way to each RoCEv2 packet. Figure 4 shows the
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Vol. 22 No. 3 Mar. 2024

performance improvement in WRITE operation
mode. With this QD configuration, the overall performance of RDMA for long-distance communication
can be increased more than with standard RDMA.
However, this framework requires a large amount ofmemory resources on the SmartNIC; thus, other metrics, except network bandwidth, may deteriorate.
5. RDMA WAN accelerator
5.1 Design
The RDMA over Open APN framework performs
better than standard RDMA because it can consume
many memory resources on SmartNICs. In addition,a large QD might cause long queuing latency or
unstable behavior of network processing. Therefore,
another approach is needed such as accelerating the
network performance of RDMA for long-distance78

Bit rate (Gbit/s)

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RDMA message size (byte)

Fig. 4. RDMA throughput comparison between standard RDMA and the RDMA over APN framework.

Local

RDMA WAN
Accelerator Software

100GbE RNIC

100GbE RNIC

port0

port0

port1

port1

Network

Remoteemulator
100GbE RNIC
port0

port1

port0

port1

Fig. 5. The experimental setup for evaluating throughput of RDMA WAN accelerator.

communication to quickly return an ACK message toreduce its waiting time. Thus, we also developed an
RDMA WAN accelerator that creates pseudo-ACK
messages. Our RDMA WAN accelerator transparently works and monitors RDMA messages, which
are exchanged between Local and Remote, to produce pseudo-ACK messages.
5.2 RDMA pseudo-ACK
To emulate the original ACK message, threeparameters have to be accurately reproduced, i.e.,
packet sequence number (PSN), destination QP number (dstQPN), and message sequence number (MSN).
As PSN is embedded in each RDMA message, our
RDMA WAN accelerator can trace it with RoCEv2
packets. Since dstQPN and MSN are not incorporated
in an RDMA message, they need to be obtained fromthe QP configuration in both Local and Remote.
Therefore, to acquire dstQPN and MSN, our RDMANTT Technical Review

Vol. 22 No. 3 Mar. 2024

WAN accelerator traces and estimates them byanalyzing the setup messages of RDMA CM (communication management) before RDMA message
transmission.
5.3 Performance evaluation
We evaluated the performance of the WRITE
operation in RC of RDMA using our RDMA WAN
accelerator. Our experimental system is the same asthat used to evaluate the RDMA over Open APN
framework but without NVIDIA ConnectX5-VPI
NIC and RDMA WAN accelerator, as shown in Fig. 5.
Our RDMA WAN accelerator is a software instanceand implemented using Data Plane Development Kit(DPDK) 20.11.1 [13]. Figure 6 shows our measurement results. Compared with the RDMA over OpenAPN framework, the RDMA WAN accelerator starts
to improve network throughput for smaller message
sizes, i.e., 256 bytes, and in almost all message sizes
79

Bit rate (Gbit/s)

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RDMA message size (byte)

Fig. 6. R
 DMA throughput comparison between standard RDMA, the RDMA over APN framework, and RDMA WAN
accelerator.

except 8192 bytes, the RDMA WAN accelerator performed better. In this measurement, as the QD configuration is the default setting with the RDMA WAN
accelerator, we expect more stable behavior of
RDMA and other network processing than with the
RDMA over Open APN framework.
6. Conclusion
We proposed two long-distance RDMA-acceleration frameworks, i.e., RDMA over Open APN and
RDMA WAN accelerator. For more network throughput, the RDMA WAN accelerator is more applicablethan the RDMA over Open APN framework. However, the RDMA over Open APN is easy to use
because no additional components are required. With
these RDMA-acceleration frameworks, we canachieve high-performance data transfer over longdistance networks.
References
[1]

[2]

Q. Cai, S. Chaudhary, M. Vuppalapati, J. Hwang, and R. Agarwal,“Understanding Host Network Stack Overheads,” Proc. of the ACM
Special Interest Group on Data Communication (SIGCOMM) 2021
Conference (SIGCOMM ’21), pp. 65–77, Virtual, Aug. 2021. https://doi.org/10.1145/3452296.3472888
InfiniBandTM Architecture Specification, https://www.infinibandta.

NTT Technical Review

Vol. 22 No. 3 Mar. 2024

org/ibta-specification/
D. Géhberger, D. Balla, M. Maliosz, and C. Simon, “Performance
Evaluation of Low Latency Communication Alternatives in a
Containerized Cloud Environment,” 2018 IEEE 11th International
Conference on Cloud Computing (CLOUD), pp. 9–16, San Francisco,
CA, USA, 2018. https://doi.org/10.1109/CLOUD.2018.00009[4] Website of NTT, What is IOWN concept, https://group.ntt/en/csr/
group/iown.html[5] IOWN Global Forum, “Data-Centric Infrastructure Functional
Architecture,” Ver. 2.0, Mar. 2023. https://iowngf.org/wp-content/
uploads/2023/04/IOWN-GF-RD-DCI_Functional_Architecture2.0.pdf[6] IOWN Global Forum, “RDMA over Open APN PoC Reference,” Ver.
1.0, July 2022. https://iowngf.org/wp-content/uploads/formidable/21/
IOWN-GF-RD-RDMA_over_Open_APN_PoC_Reference_1.0.pdf[7] Y. Sugawara, T. Yoshino, H. Tezuka, M. Inaba, and K. Hiraki, “Effectof Parallel TCP Stream Equalizer on Real Long Fat-pipe Network,”
Proc. of 2008 Seventh IEEE International Symposium on Network
Computing and Applications, pp. 279–282, Cambridge, MA, USA,
July 2008. https://doi.org/10.1109/NCA.2008.50[8] S. Floyd, “HighSpeed TCP for Large Congestion Windows,”
RFC3649, Dec. 2003.
[9] T. Kelly, “Scalable TCP: Improving Performance in Highspeed WideArea Networks,” ACM SIGCOMM Computer Communication
Review, Vol. 33, No. 2, pp. 83–91, Apr. 2003. https://doi.
org/10.1145/956981.956989[10] L. Xu, K. Harfoush, and I. Rhee, “Binary Increase Congestion Control(BIC) for Fast Long-distance Networks,” Proc. of IEEE INFOCOM
2004, Vol. 4, pp. 2514–2524, Hong Kong, China, Mar. 2004. https://doi.org/10.1109/INFCOM.2004.1354672[11] S. Ha, I. Rhee, and L. Xu, “CUBIC: A New TCP-friendly High-speed
TCP Variant,” ACM SIGOPS Oper. Syst. Rev., Vol. 42, No. 5, pp.
64–74, July 2008. https://doi.org/10.1145/1400097.1400105[12] perftest on GitHub, https://github.com/linux-rdma/perftest[13] DPDK, https://www.dpdk.org/[3]80

Regular Articles

Hitoshi Masutani

Tomoya Hibi

Senior Research Engineer, Advanced Networking Research Group, Frontier Communication Laboratory, NTT Network Innovation Laboratories.
He received a B.E. in communication engineering, and M.E in electrical, electronic andinformation engineering from Osaka University
in 1999 and 2001 After joining NTT Network
Innovation Laboratories in 2001, he studied
multicast networking and SIP (session initiation
protocol)-based home networking. In 2005, hejoined the Visual Communication Division of
NTTBizlink, where he was responsible for developing and introducing visual communication
services, including an IP-based high-quality
large-scale video conferencing system and realtime content delivery system on IPv6 multicast.
He also worked on developing their service ordermanagement system and network management
system for video conference services.
When he returned to NTT Network Innovation
Laboratories in 2012, he has been engaged inresearch and development (R&D) of programmable network nodes, including softwaredefined networking (SDN) and network function
virtualization (NFV), e.g., high-performance
software openflow switch “Lagopus”. When hejoined NTT Network Technology Laboratories in
2019, he has been engaged in R&D of deterministic communication services’ technologies,
including time sensitive networking. He has beendeveloping high-performance and low-latency
network technologies since 2023.

Research Engineer, NTT Network Innovation
Laboratories.
He received a B.E. and M.E. in computer science and engineering from Toyohashi Universityof Technology, Aichi, in 2010 and 2012. He
joined NTT Network Innovation Laboratories in2012 and studied software networking andpacket processing techniques. From 2021 to2023, he was with the New Business Development Headquarters of NTT EAST, where he wastasked with developing private cloud services.
His current research focuses is on fast, long-distance data transfer over the IOWN APN.

Junki Ichikawa

Research Engineer, Frontier Communication
Laboratory, NTT Network Innovation Laboratories.
He received a B.E. and M.E. in electronics andinformation engineering from Yokohama
National University, Kanagawa, in 1990 and
1992. In 1992, he joined NTT Software Laboratories and studied network management andhigh-speed Internet. He is currently studying
network architectures and protocols in optical
networks. He is a member of IEICE, the Information Processing Society of Japan (IPSJ), and the
Association for Computing Machinery.

Research Engineer, Advanced Networking
Research Group, Frontier Communication Laboratory, NTT Network Innovation Laboratories.
He received a B.E. and M.E. from Chiba University in 2012 and 2014. He joined NTT Network Innovation Laboratories in 2014 and studied SDN and NFV technologies. From 2017 to
2019, he was a member of the Lagopus project,which is an open source project for developing asoftware openflow switch and software multifunction router called “Lagopus”. He demonstrated Lagopus switch and router for ShowNet,
which is a project to build a network within avenue at Interop Tokyo in 2017, 2018, and 2019.
He is currently studying RDMA-acceleration
technologies for long-distance optical networks
such as the IOWN APN. He is a member of theInstitute of Electronics, Information and Communication Engineers (IEICE) of Japan.

Kiwami Inoue

Advanced Networking Research Group, Frontier Communication Laboratory, NTT Network
Innovation Laboratories.
She received an M.S. from Graduate School of
Science and Technology, Doshisha University,
Kyoto, in 2020 and joined NTT Network Innovation Laboratories the same year. She is studying
multi-terminal and large capacity memory-tomemory transfer technology.

NTT Technical Review

Vol. 22 No. 3 Mar. 2024

Kazuaki Obana

Senior Research Engineer, Supervisor, NTT
Network Innovation Laboratories.
He received a B.E. and M.E. in electrical engineering from Waseda University, Tokyo, in 1995
and 1997. After joining NTT in 1997, he wasengaged in R&D for more than 25 years on priority queuing by time and place information, proxydesign with shaping functions, a fast transmission system with multilane aggregation, home
information and communication system on customer premises equipment, programmablenodes, SDN, NFV and smart data science. Since
2021, he has been active in autonomous optical
path control at NTT Network Innovation Laboratories.

Takeshi Kugimoto

Tsuyoshi Ogura

Senior Research Engineer, NTT Network Innovation Laboratories.
He received a B.E. and M.E. in system engineering from the Kobe University, Japan, in 1992
and 1994. He joined NTT Laboratories in 1994
and investigated high-speed network protocols
and video transmission systems. He is currently
with NTT Network Innovation Laboratories,
where he is studying applications of network
virtualization systems. He is a member of IEICE
and IPSJ.

81

Regular Articles

Koki Yube

Advanced Networking Group, Frontier Communication Laboratory, NTT Network Innovation Laboratories.
He received a master’s degree in engineeringfrom Keio University, Kanagawa, in 2022 andjoined NTT the same year.

Hirokazu Takahashi

Senior Research Engineer, Supervisor, NTT
Network Innovation Laboratories.
He received a B.E. and M.E. in electrical engineering from Nagaoka University of Technology,
Niigata, in 2000 and 2002. He joined NTT Network Innovation Laboratories in 2002, where hestudied multicast technologies and high-performance software packet processing technologies.
He then joined NTT Communications in 2010
where he developed network services such as
IPv6 access and DDoS (distributed denial ofservice) protection. He returned to NTT Network
Innovation Laboratories in 2013. His current
research is on high-performance and low-latency
communication technologies.

NTT Technical Review

Vol. 22 No. 3 Mar. 2024

Koichi Takasugi

Executive Research Engineer, Director of
Frontier Communication Laboratory, NTT Network Innovation Laboratories and Guest Professor of Graduated School of Information Scienceand Technology at Osaka University.
He received a B.E. in computer science from
Tokyo Institute of Technology, M.E. from Japan
Advanced Institute of Science and Technology,
Ishikawa, and Ph.D. in engineering from Waseda
University, Tokyo, in 1995, 1998, and 2004. He
was involved in the design and standardization of
the Next-Generation Network (NGN) architecture. He has implemented and installed superhigh-density Wi-Fi systems in several footballstadiums. He is currently leading research on the
network architecture and protocols in optical andwireless transport networks.

82

Global Standardization Activities

Activity Report of TTC Bridging theStandardization Gap Working GroupJiro Nagao
Abstract

The Bridging the Standardization Gap (BSG) Working Group of the Telecommunication Technology
Committee (TTC) held a meeting in October 2023 in Tokyo and Kitakyushu, Japan. The meeting wasattended by university professors and government officers from the Asia-Pacific region who work in thefields of information and communication technology (ICT) deployment and promotion of standardization. The topics of the meeting were introduction to the use of ICT in Japan (in fields such as agriculture,
aquaculture, education, environment, medical care and disaster response), and discussion between theparticipants.
Keywords: TTC, BSG, ICT

1. What is BSG?
The Bridging the Standardization Gap (BSG) activity in general aims to support developing countries
and rural areas in using information and communication technology (ICT), deploying standardized technologies, and promoting standardization. BSG isessential to maximize the benefit of global standardization and improve people’s lives. BSG is also oneof the five strategic objectives of International Telecommunication Union (ITU)’s standardization sector(ITU-T) [1]. Global standards show their full potential when deployed worldwide because global standards aim to connect the world with the same interfaces, give everyone the same benefit with the same
look-and-feel, and reduce cost by the economy ofscale. At first glance, BSG seems like a support activity only beneficial to developing countries and rural
areas, but it is also beneficial to developed countries
because of cost reduction, market expansion, andimprovement in convenience, as described above.
2. BSG activities in TTC
The Telecommunication Technology Committee(TTC), the Japanese standards developing organization (SDO) for discussing the contributions fromNTT Technical Review

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Japan to ITU-T, has been active in BSG in the AsiaPacific region for over 10 years through its BSG
Working Group (WG), with “SHARE” (Success &Happiness by Activating Regional Economy) as its
slogan. The BSG WG has collaborated with the AsiaPacific Telecommunity (APT), the ITU correspondent in the Asia-Pacific region, and developed trusting relations with government organizations andSDOs in the region. On the basis of such relations, it
has held several workshops and training sessions
every year along with the annual SHARE Meetings.
Its activities in 2023 are listed in Table 1. NTT considers BSG activity important and has sent members
to the BSG WG since its establishment. The author
currently acts as the vice chair of the WG. This article
reports the 19th SHARE Meeting held on 16–18
October 2023.
3. The 19th SHARE Meeting
Table 2 shows the summary of the 19th SHARE
Meeting. In the morning of the first day, after the
opening ceremony and summarizing report of theprevious meeting, the recent activities were reported
from the participants. Their recent major activities
were shared, and active discussion was held. Figure 1
shows a photo of the first day. The joint online TTC
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Global Standardization Activities

Table 1. List of events by TTC BSG WG in FY2023.
Date

Event

19 Apr. 2023

Presentation to add the result of “Behavioural Analytics and Real-time Tracking of Patients Using IoT and RFID” to
APT report at EG-BSG in 35th ASTAP

18–19 Sept. 2023

Workshop for IoT human resources development, Bangkok, Thailand

16–18 Oct. 2023

19th SHARE Meeting in Tokyo and Kitakyushu, Japan

13–17 Nov. 2023

Workshop for bridging the gender gap and training mobile solution architects for local issues, Japan

27 Nov.–1 Dec. 2023

APT Training Course: Training Experts and Foster Managements in Standardization of ASTAP and related
Organizations -- Sharing trends of emerging technologies in standardization --, online

ASTAP: APT Standardization Program
EG-BSG: Expert Group BSG
RFID: radio frequency identification

Table 2. Summary of 19th SHARE Meeting.
Dates

16–18 October 2023

Venue

Days 1, 2: Tokyo (TTC)
Day 3: Kitakyushu (Hibikinada Farm, Kyushu Institute of Technology)

Participants

TTC

Dr. Iwata, President, TTC
Dr. Inoue, Advisor, TTC
TTC BSG WG members

6 personsPhilippines

Professor

1 person

Malaysia

Professors

2 personsThailandProfessor, faculty member

2 personsIndonesia

Professor, faculty member

2 personsVietnam

Faculty member, government officers

3 persons16 October

Activity report from participants

Schedule

Joint online TTC seminar with IoT Smart City WG on Recent Technology
for Smart Agriculture and International Standardization Activity
17 October

Summary and discussion
Report drafting

18 October

Visit Hibikinada Farm
Visit Kyushu Institute of Technology

Fig. 1. Discussion (first day).

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Global Standardization Activities

Fig. 2. Site visit at Hibikinada Farm (second day).

seminar with TTC’s Internet of Things (IoT) Smart
City WG on Recent Technology for Smart Agriculture and International Standardization Activity washeld in the afternoon. National activities related tosmart cities in Japan, and some advanced enterprise
activities in agriculture and aquaculture with ICT
were reported. Activities of the ITU-T Focus Groupon Artificial Intelligence (AI) and IoT for Digital
Agriculture (FG-AI4A), which studies application of
AI in agriculture, and activities of the ITU-T Study
Group 20 (IoT and smart cities and communities(SC&C)), which studies IoT and smart cities, werealso reported. The use of ICT in disaster resilience in
the ASEAN (Association of Southeast Asian Nations)community was also reported by one of the SHARE
members and opinions were exchanged. On the second day, the summary and report of the first day were
produced in the morning, and the participants travelled to the next venue for the third day, Kitakyushu,
Fukuoka Prefecture, in the afternoon.
The morning of the third day was the site visit to thelarge-scale high-tech farm, Hibikinada Farm, as a
cutting-edge example of agriculture using ICT in
Japan. Figure 2 shows a photo of the site visit. Theview of 200,000 tomato plants more than twice thehuman height in 8.5 ha of land was astonishing.
Questioning and discussion with the staff were enthusiastic because there were participants such as professors who study the use of ICT in agriculture andaquaculture in the Asia-Pacific region. Details of ICT
usage at the farm was presented after the observation.
Computerized monitoring, management and controlof the temperature, moisture, carbon dioxide, andculture fluid was presented. The discussion was
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Fig. 3. P
 resentation and discussion at Kyushu Institute ofTechnology.

active between the farm and the participants. For
example, when the farm presented that they usedcoco peat as a nutriculture medium, one of the participants contributed information that coco peat isuseful because it has no nutrients and low risk of
diseases. The topic went beyond cultivation management to social systems to research budgeting, as theparticipants included university professors and government officers. It was the moment the full significance of the BSG activity was felt where common
issues are shared, and solutions are discussed amongpeople from many countries.
In the afternoon, they visited Kyushu Institute ofTechnology. Topics such as underwater robot control
and aquafarming were presented (Fig. 3). Questions
from the participants went deep into the research,such as why a camera was used and not sound, which
is used in fish sonar.
4. Conclusions
The 19th SHARE Meeting, an activity by the BSG
WG of the TTC, held in October 2023 was reported.
University professors and government officers fromthe Asia-Pacific region who work in the field of ICT
utilization participated in the Meeting. Example practices in Japan were introduced and discussions were
held to support and promote deployment of ICT indeveloping countries and rural areas. Although it was
not the focus of this Meeting, the BSG WG also holds
standardization-skill-training courses (Table 1). The
BSG WG will strive to bridge the standardization gap
in the Asia-Pacific region by supporting and promoting deployment of ICT and standardization-skill
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training.

[2]

References
[1]

[3]

www.itu.int/en/ITU-T/gap/Pages/default.aspx
Website of TTC, BSG WG (in Japanese), https://www.ttc.or.jp/
activities/wg/bsg/asia_promotion
Website of TTC, SHARE, https://www.ttc.or.jp/e/globalactivity/share

Website of ITU-T, Bridging the Standardization Gap (BSG), https://Jiro Nagao

Senior Manager, Standardization Office,Research and Development Planning Department, Research and Development Market Strategy Division, NTT Corporation.
He received a Ph.D. in information sciencefrom Nagoya University, Aichi, in 2007 andjoined NTT the same year. From 2007 to 2011, he
was engaged in research and development ofimage-processing and content-distribution technology. From 2012 to 2017, he worked for NTT
Communications, serving as the technical leaderof commercial video-streaming services. From2017 to 2021, he was engaged in research anddevelopment of immersive media and presentation technology at NTT Service Evolution Laboratories. Since 2022, his mission has been promoting standardization activities for global
deployment of NTT research and development(R&D) technologies and services at Standardization Office, R&D Planning Department, NTT
Corp. He is currently an associate rapporteur of
ITU-T Study Group 16 Question 8 (Immersive
Live Experience since 2022).

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Report on the NTT R&D FORUM
2023 — IOWN ACCELERATIONNTT R&D Forum Secretariat
Abstract

NTT R&D FORUM 2023 ― IOWN ACCELERATION was held from November 14th to 17th, 2023.
The following is an overview of the Forum.
Keywords: R&D Forum, IOWN, latest technology

1. NTT R&D FORUM 2023 Overview
The Innovative Optical and Wireless Network(IOWN), which began service in March 2023, issteadily advancing. The NTT R&D FORUM 2023,
with the title, “IOWN ACCELERATION,” introduced some of the latest developments in IOWN,
such as NTT’s large-language model (LLM), called“tsuzumi” (announced in November 2023), which
has been attracting attention in various domains.
On the preview day, November 13, only pressrelated guests were invited, so that various TV programs and other media could broadcast an overview
of the event. This resulted in several articles posted innewspapers and on the web. The main event from
November 14 to November 17 was also a great success, with approximately 12,000 visitors invited fromJapan and overseas attending at the physical venue,
the NTT Musashino R&D Center. The online venue
was also a great success, receiving approximately
19,000 visitors from around the world.
A total of nine speeches were presented at thephysical venue, namely Keynote Speeches with NTT
management speaking about NTT business and technology strategies, followed by Special Sessions withNTT and external experts introducing hot global
technology themes, and MIRAI Seminars (Outlook)in which other well-known presenters from various
domains discussing their future vision for the world.
These same lectures were also presented online at the
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virtual venue.
2. Keynote Speeches
Three keynote speeches were given. The first wasby Akira Shimada, NTT President and CEO, on
NTT’s approach contributing to society and a vision
for the future involving the new research themes of
IOWN and NTT’s LLM tsuzumi. The second was by
Sachiko Oonishi, NTT Executive Vice President,
Head of Research and Development and Market
Strategy, on NTT’s research and development (R&D)
efforts from both “product-out” and “market-in”
approaches, and the third was by Shingo Kinoshita,
NTT Senior Vice President and Head of Research andDevelopment Planning, providing technical descriptions of IOWN and NTT’s LLM, and interoperations
between these technologies.
2.1 K
 eynote Speech 1: Innovating a Sustainable
Future for People and Planet
NTT R&D Initiatives
NTT President and CEO Akira Shimada opened his
speech by introducing NTT’s new R&D theme of“Innovation for a sustainable future for people andplanet,” with the major goals of resolving issues
faced by society and enhancing the well-being ofpeople in society. He then went on to describe IOWN
and tsuzumi, NTT’s LLM, as key technologies forachieving these goals. He then discussed how IOWN
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Photo 1. Keynote Speech 1: Akira Shimada.

Photo 2. Keynote Speech 2: Sachiko Oonishi.

and tsuzumi can solve difficult issues faced by societies around the world, such as labor shortages, environment and energy issues, aging populations andincreasing medical costs. He introduced some concrete examples of how NTT technologies have solved
issues to improve well-being in society and a vision
for the future that NTT and its partners have created
together (Photo 1).
He introduced “IOWN1.0” as the All-Photonics
Network (APN) that was launched commercially inMarch 2023 and described plans for “IOWN2.0” andbeyond, with a roadmap to advance optical technologies from the network into the computing environment. He also drew attention to a pavilion planned for
Expo 2025 in Osaka, which will enable visitors toexperience services using IOWN technologies.
He also discussed efforts making steady progress
toward the commercial release of tsuzumi that is
causing a stir in the field of generative artificial intelligence (AI) and has been attracting attention aroundthe world. He then stressed the great potential of having these two technologies, to solve social issues andmake great contributions to realizing well-being insociety.
He concluded the speech with a message of “innovating a sustainable future for people and planet,”stating that NTT will continue working and creating
innovation for people and the planet.

spoke about IOWN, with concrete examples of commercial application for full implementation in society. With the theme and title, “IOWN ACCELERATION —Imagination and Creation—,” she presented
a new vision for the future created through the accelerating plan and implementation of IOWN, from both“product-out” and “market-in” R&D perspectives(Photo 2).
In her opening she said, “I hope that you can now
feel this idea (of IOWN) coming to life,” and presented a roadmap to telecommunications breakthroughs for IOWN2.0, brought by progress in elemental technologies in various fields such as optoelectric integration. With key points in the speech,
she also identified historical milestones developed by
NTT in the form of a quiz, giving background on how
NTT was able to achieve those breakthroughs.
She also introduced solutions to issues that NTT
has promoted in a wide range of fields; touching on
areas considered basic to human life such as clothing,food, and shelter and presenting a new “market-in”
R&D perspective that NTT is adopting, which focuses on technologies and solutions needed to improve
people’s well-being in society.
Finally, she described NTT’s goal of creating value
for the social well-being of people and the planet,
toward an exciting future realized by NTT.

2.2 K
 eynote Speech 2: IOWN ACCELERATION—Imagination and Creation—
NTT Executive Vice President, Head of Researchand Development Market Strategy Sachiko Oonishi
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2.3 K
 eynote Speech 3: LLM+×IOWN —The
advancement of IOWN, the launch of NTTʼs
LLM, and their synergy—
NTT Senior Vice President and Head of Researchand Development Planning Shingo Kinoshita spoke
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Finally, he also reflected on the “fountain of knowledge” mindset inherited from NTT R&D. He
described three elements comprising this mindset,
which are to promote R&D, to implement research
results practically, and to implement them in society
together with partner enterprises.
3. Special Sessions
The Special Sessions were speeches given by NTT
and external experts on the key topics for the R&D
FORUM 2023, IOWN and NTT’s LLM tsuzumi,
examining future prospects along three trending
themes in society.
Photo 3. Keynote Speech 3: Shingo Kinoshita.

about progress regarding NTT’s LLM tsuzumi,
which was announced in November 2023, and also
IOWN and the synergies between these two technologies. Using “LLM+×IOWN” as a theme and providing much technical explanation, he described the
far-reaching potential of combining these technologies in various ways (Photo 3).
LLM tsuzumi, which is bringing new perspectives
to the LLM field, has four major features: (1) It islightweight and has low power consumption, (2) It
has strong linguistic capability (especially Japanese),(3) It is flexible for customization, and (4) It is multimodal. These were each introduced in detail, including the underlying technologies that make them possible, and showing the resulting high-performance.
Regarding synergies with IOWN, he describedpractical experiments related to the dramatic developments in LLMs. This included experiments that
overcame physical distance, combining computing
resources to perform LLM training and inference
efficiently, using graphics processing units (GPUs) ina datacenter roughly 100 km away to process training
data held locally, and treating datacenters that are farapart as though they were a single datacenter. He also
described plans to expand experiments in the field
globally in the future.
He also announced a joint R&D initiative with
Sakana AI, a Tokyo-based startup that is attracting
attention globally. He suggested that cooperation
between these companies in the field of AI, for which
they both have great affinity, will have great influence on how generative AI should advance and how
architectures are considered in the future.
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3.1 S
 pecial Session 1: IOWN opens up a datadriven era
Hiroaki Nagashii, VP, Strategic Client Group,
Oracle Corporation Japan, and Yoshisato Fukatsu,
Enterprise Architect, Industry, Value and Architecture, Oracle Corporation Japan, were invited to givea lecture on the roles IOWN and Oracle play in realizing a data-driven society and their vision for thatsociety (Photos 4, 5).
Mr. Nagashii introduced his vision for the future,
based on the vision of the founder of Oracle Corporation. He expressed his desire for Oracle to contributeto realizing a data-driven society and how that desire
is reflected in their efforts and achievements utilizing
data in various domains, including fields that require
critical elements such as renewable energy.
He also indicated they have high expectations forthe paradigm shift in implementing a data-driven
society due to the IOWN features of high-security,
high-capacity, and low latency. Mr. Fukatsu thenintroduced some concrete “IOWN × Oracle” solutions from the perspectives of potential and feasibility. He described concepts for future solutions createdutilizing the high-capacity, low-latency communications infrastructure implemented by NTT with
IOWN, together with the best data-management
technology in the world from Oracle Corp. He
expressed particularly high expectations for NTT
regarding the high security technology in IOWN.
Finally, Mr. Nagashii talked about his strong desire
to create a society in which “no one is left behind” inthe future, after further collaboration between NTT
and Oracle results in dramatic progress in technology.
It was a captivating speech regarding co-creation by
NTT and Oracle in the future.

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Photo 4. Special Session 1: Hiroaki Nagashii.

Photo 6. Special Session 2: Kyosuke Nishida.

their well-being in any environment. In the speech hedemonstrated a conversation with tsuzumi using concrete questions. LLM tsuzumi even answered questions that are unavoidable when discussing AI, suchas “How can AI be trained to follow rules?”The session gave an impression of the high performance of tsuzumi through the responses and sense of
the issues it presented, toward a world in which thetsuzumi AI and people can coexist.

Photo 5. Special Session 1: Yoshisato Fukatsu.

3.2 S
 pecial Session 2: Does AGI dream of livingwith Humans? —R&D of LLM “tsuzumi”—
In the first part of Special Session 2, NTT Human
Informatics Laboratories’ Senior Distinguished
Researcher Kyosuke Nishida presented a detailed
introduction to R&D on NTT’s LLM tsuzumi, and its
features (Photo 6).
Mr. Nishida, who drove R&D on tsuzumi, included
a conversation with tsuzumi as the first section of his
speech, showing the astonishing achievement andhigh performance of tsuzumi from the beginning.
He then presented his research vision of creating an
artificial general intelligence (AGI) thinking engine
that can naturally coexist with people and support
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3.3 S
 pecial Session 2: Natured Inspired Intelligence and a New Paradigm for LLM
For the second half of Special Session 2, we invited
David Ha, Co-Founder CEO, Sakana AI, and Llion
Jones, Co-Founder CTO, Sakana AI (Photo 7).
David Ha and Llion Jones spoke about future directions for language models, focusing on LLMs. DavidHa surprised the audience by indicating that, although
he is among a minority in the current LLM community, he thinks that “even if the extremely large models become even larger, they will not be possible tohandle the complexity of the real world.” He went on
to say that based on ideas from nature, “human intelligence is largely a collective intelligence,” and fromthat perspective, rather than having a single, gigantic
LLM, LLMs must evolve to cooperate and adapt
dynamically to conditions, so that multiple LLMs
with various features cooperate to produce intelligence.
He also talked about his expectations for the potential of Japan itself. He believes that Japan can makeits presence known globally in AI, and spoke passionately about this as one of the reasons Sakana AI
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Photo 7. Special Session 2: David Ha (left) and Llion Jones (right).

Photo 8. Special Session 3: Timothy McKenna (left), Bob Byer (right).

established its base in Japan.
Llion Jones, also from Sakana AI, then described“character-level modeling” in detail as one of thestrengths of tsuzumi. He explained that current
LLMs, which mainly focus on English, use bothcharacter-level and word-level models, but heemphasized that they would need to transition tocharacter-level models. He also pointed out the surprising fact that there is redundancy in AI learning
between different languages, so there is still potential
yet to be identified in AI.
In their speeches, both speakers showed the affinityof both NTT and Sakana AI for the forms and ideal
architectures of LLMs in the future, so the session
raised expectations for the commercialization andlater development of tsuzumi, with its particular
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strengths in the Japanese language.
3.4 S
 pecial Session 3: Lithium Niobate Photonics
In The Era of AI
In this session, Bob Byer, the William R. Kenan, Jr.
Professor Emeritus of Applied Physics, Stanford University, and Timothy McKenna, Principal Scientist,
Physics & Informatics Laboratories, NTT Research,
expanded on the topic, including episodes involving
breakthroughs from their long history and tradition(Photo 8).
This session introduced the history and backgroundof photonics using lithium niobate (LN), which is oneof the most widely used functional optical materials.
Bob Byer, an LN pioneer, described the “1st-generation” history in the 1960s and 1970s, and Timothy91

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McKenna, who led an NTT Research team in recent
years driving technical innovation and commercialization, described the “2nd-generation” since the1980s, and the following “3rd-generation.”
A surprising revelation was that during his research
Mr. Byer once dropped and damaged a photonic crystal, but this later led to a technical breakthrough. His
answer to what to do with the damaged crystal isrelated to recent rapid advances in fabrication technologies. Now that fabrication of LN devices withnanometer precision has been achieved, LN is
expected to play an important role in implementing
high-speed, efficient communication in datacenters.
The importance of thin-film LN (TFLN) photonics is
also predicted to increase even more due to the rapidly increasing size and bandwidth requirements of
AI clusters, an expanding photonics market, and the
expanding scale and requirements of datacenters.
Incredibly, the size of the TFLN market has exceeded
two billion dollars in 2023, just five years since it
appeared as a market. Overall, the session was very
entertaining from two individuals who have been
instrumental in the field of LN.
Finally, Timothy McKenna and Bob Byer expressed
their hopes to make further great contributions tosolving hardware issues, unlocking the fascinationand hidden potential of TFLN, and building excitement for a bright future.
4. MIRAI Seminars (Outlook)
Well-known experts from various fields wereinvited to discuss visions for the future from theirown perspectives. These future visions were given
substance by discussing them in light of NTT’s technologies and initiatives. A common theme in the threeseminars could be stated as “Bringing to light what
could not be seen before.”
4.1 M
 IRAI Seminar 1: How the Technology Innovation Brings “Space within Your Reach”
President & CEO of Axelspace Corporation Yuya
Nakamura spoke about technical innovation in satellite development and use, the importance of observations from space, and the relationship between
humans and space in the future (Photo 9).
Space business is seen as a rapidly maturing industry around the world, with a market expected to
exceed one trillion dollars by 2040. Mr. Nakamura
spoke about how “observations from space” are an
important element resulting from use of satellites. He
emphasized that satellite imagery is used for more
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Photo 9. MIRAI Seminar 1: Yuya Nakamura.

than just smart agriculture; that conditions on earth
and in space observed from satellites are importantdata for understanding the world accurately and making improvements in all fields, and can also be usedas evidence.
He also introduced a new, small satellite businessthat provides one-stop satellite use in a short periodof time, incorporating setting objectives, development, manufacturing, launch and operations, and hediscussed how this initiative expands the potential forsatellite use in fields and industries more removed
from conventional space business and “brings
democracy to space.”
Mr. Nakamura also expressed strong expectations
for the impact of optical communications being
advanced by NTT’s IOWN initiative, as a gamechanger for space business. Space Compass Corp.
and Axel Space Corp. are already collaborating withNTT and SKY Perfect JSAT Corporation to expand
optical communications into space. Mr. Nakamura
concluded his speech by emphasizing that he willcontribute to the next-generation communications
infrastructure to be built by Space Compass and further expand cooperation.
4.2 M
 IRAI Seminar 2: Future Health with Digital
Technology —Autonomic Nervous System
and Intestinal Environment
Hiroyuki Kobayashi, Professor, Department ofResearch and Development for Elderly Physical
Function, Juntendo University Graduate School of
Medicine, was invited and gave an eye-opening
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Photo 10. MIRAI Seminar 2: Hiroyuki Kobayashi.

Photo 11. MIRAI Seminar 3: Hiroaki Miyata.

new solutions available through advances in technology (Photo 10).
Prof. Kobayashi spoke about how we assume thatdata science basically “makes the invisible visible”
by luck, but actually these facts are established byscience. He described to a surprised audience how
this does not just apply to illness and infection, butthat sports are also explained by science using a golf
example. From the perspective of “reproducibility,”
which is an important element of medicine and sports
science, the level of R&D and technology that NTT isadvancing is highly regarded, such as the “motorskill transfer technology” which brings potential to
the world of medicine for applications such as remotesurgery. He gave the impression that we have reached
an age where even surgical skills can be transferredfrom experienced doctors to trainees.
He then expanded his topic to “What is health?”,talking about how our intestinal environment is an
important element for living a healthy lifestyle, andwhy yoghurt has a positive effect on this environment. He explained the importance of the intestinal
environment for a healthy lifestyle, adding a humorous metaphor of yogurt being a “transfer student” inthat yogurt stimulates its environment like a transfer
student stimulates unfamiliar students.
To end the seminar, he explained how various
obstacles to a healthy lifestyle can lead to a negative
spiral in behavior and thinking, while also taking
questions from the audience.

4.3 M
 IRAI Seminar 3: The Vision of a Future
Society Beyond DX (Digital Transformation)
Hiroaki Miyata, Professor and Chair, Department
of Health Policy Management, School of Medicine,
Keio University, spoke mainly on the theme of whatkind of future can be created in a world focused on
digital transformation (DX) and after the IOWN concept is implemented (Photo 11).
Prof. Miyata reflected on how work-life haschanged greatly as application of IT has progressed
and information gathering with technologies likesearch engines has spread, and the large impact thatgenerative AI, which is now poised to permeate society, is having on a wide range of fields. He talked
about how generative AI is organizing issues, butwhat people need is to look at the future and to position technology accordingly. He said that a perspective of realizing our ideals rather than optimizing ourcurrent work with technologies like generative AI
and DX is important and has not been achieved yet.
He also emphasized the value in the ability to “connect”—overcoming physical distances and recognize
and sympathize with each other—by consolidating
communication infrastructure and expanding social
networking services, and expressed hope that suchconnections will be strengthened by NTT’s IOWN
initiatives.
On the other hand, he also spoke of the “Great
reset” being advocated by the World Economic Forum(WEF) and further changes coming to values and thepositioning of the economy. From that important
aspect, he closed his speech by indicating the importance of an approach that emphasizes “maximum

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Fig. 1. The “tsuzumi” Large Language Model.

well-being with maximum diversity,” rather than the
traditional values of “maximizing happiness for the
many,” and “creating a future living together” with
IOWN-based data sharing.
5. Technical Exhibits
The “IOWN Pick UP” technical exhibits presented
NTT’s LLM tsuzumi as a key technology and also
introduced the latest developments and presented
demonstrations of IOWN related technologies divided into three timelines, according to level of maturity,
as “IOWN Now,” “IOWN Evolution,” and “IOWN
Future.” There were also exhibits on 18 other wideranging themes categorized on timelines, such as
next-generation computing infrastructure, sustainable technology, APN, and next-generation wirelesstechnology. These showed how progress in various
domains is related to the implementation of IOWN.
5.1 IOWN Pick Up
The spotlight was placed on NTT’s LLM tsuzumi,
which was announced in November 2023. It brings
together R&D results that NTT has been cultivatingin natural language processing and other technologies, and has demonstrated a range of communication
possibilities with language and beyond.
(1) The “tsuzumi” Large Language Model
The ‘“tsuzumi” Large Language Model’ exhibit
presented to the world NTT’s long-awaited tsuzumi
technology, which has been attracting much attention. It described the technology and introduced its
main features as “lightweight and proficient in Japanese,” and “flexible customization.” Worth noting
was that tsuzumi is lightweight enough to operate ona single GPU in a local environment. By increasing
the quality and quantity of language-training data, it
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has achieved the highest performance in Japan while
also greatly reducing power consumption and operating costs. The exhibit also showed that tsuzumi wasable to derive correct responses by having smaller,
specialized LLMs cooperate rather than having asingle large LLM, as with earlier LLMs. Anothermajor feature is that tsuzumi has a generalized LLM
as a base, and “adapters” can be applied to it, enablingflexible customization for a customer’s requirementsor characteristics of an industry. We can anticipate
these features being utilized in a wide range of applications (Fig. 1).
(2) “tsuzumi” for understanding graphic documents
LLM tsuzumi has also been expanded to communication beyond language. In “tsuzumi for understanding graphic documents,” tsuzumi demonstrated abilities as though the LLM could actually “see.” In contrast to earlier LLMs based on text data, tsuzumi isable to understand a wide range of graphical andhand-written materials and derive correct responses.
A world in which LLM’s can communicate withpeople using language, even in non-digital environments and conditions, is within sight (Fig. 2).
(3) “tsuzumi” with hearing and speaking abilities
LLM tsuzumi has also been expanded to utilize
communication with sound. In “tsuzumi with hearing
and speaking abilities,” it is able to obtain information by “hearing” voices and other sounds (Fig. 3).
By capturing non-linguistic information that is not
represented in text, such as tone, physical condition,or emotion, it demonstrated the ability to communicate more intimately with people. It introduced how
tsuzumi is not limited to vision and has expanded tocommunication using the five senses and to othermeans beyond language as shown in other exhibits as
well.

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Fig. 2. “tsuzumi” for understanding graphic documents.

Fig. 3. “tsuzumi” with hearing and speaking abilities.

Fig. 4. Photonic and electronic device technology for All-Photonics Networks.

5.2 IOWN Now
In “IOWN Now,” the current state of IOWN was
exhibited, as it advances from networks into computing. NTT research results and elemental technologies
that are starting to be used in various fields were
described, showing the major impacts they are havingon society.
(1)	Photonic and electronic device technology for
All-Photonics Networks
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“Photonic and electronic device technology for AllPhotonics Networks,” presented various advanced
devices that support APN and IOWN 2.0. Various
NTT Laboratories technologies were gathered, suchas multi-core fiber, wavelength modulation devices,
1-Tbps-class devices, and ultra-wide-band opticalswitches, and these research results are behind implementation of high capacity, low latency and lowpower in APN (Fig. 4).
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Fig. 5. Photonics-Electronics Convergence devices.

Fig. 6. IOWN APN for remote control and grasp of the on-site environment.

(2) Photonics-Electronics Convergence devices
The “Photonics-Electronics Convergence devices”
exhibit presented R&D utilizing optics in even smaller components of networks, introducing compact
photo-electric devices that can be placed in largescale integrated (LSI) circuits. As IOWN progresses
from networks to computing, this technology will be
used to apply mechanisms for converting electricalsignals to optical signals connecting progressively
smaller components, from between boards to between
semiconductor packages and then within semiconductor packages. It will contribute greatly to progresswith IOWN high-capacity, low-latency and low
power on the roadmap for the future (Fig. 5).
(3)	IOWN APN for remote control and grasp of theon-site environment
The “IOWN APN for remote control and grasp of
the on-site environment” exhibit presented anddynamically demonstrated the potential for the
IOWN features of high capacity, low latency, and low
power to be utilized to solve social issues in a moretangible way. Fine remote operation was made possible by using the APN to transmit high-definition
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video with low latency from a site, and to provide
real-time control feedback from a human operator. It
demonstrated the usefulness of APN in contributing
to addressing various issues in the constructionindustry, such as personnel shortages and ensuring
safe work environments for technicians (Fig. 6).
5.3 IOWN Evolution“IOWN Evolution” introduced everyone to a future
vision of what is close to becoming reality, opened up
through advances in IOWN occurring daily. It
showed NTT R&D to create solutions for various
social issues and to realize well-being through application of IOWN.
(1) On-demand APN and In-network video processing
The “On-demand APN and In-network video processing” exhibit displayed implementation of a nearreal-time broadcasting and distribution service andinteractive video experience. This redefines video
distribution utilizing two technology elements: atechnology providing on-demand optical paths and atechnology that can process video in its transmitted
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Fig. 7. On-demand APN and In-network video processing.

Fig. 8. Environment monitoring with optical fiber.

venue using news and video introducing culturalproperties (Fig. 7), and showed how the camera video
was delivered to the viewer without loss of time orinformation, but also that the viewer was now able toselect which of the cameras’ video to view. The factthat it can be controlled from the communications
side using a Super White Box rather than a specialized
broadcaster device also made a strong impression.
(2) Environment monitoring with optical fiber
IOWN is also being developed to utilize existing
equipment, creating new value. The “Environment
monitoring with optical fiber” exhibit introduced
technology that uses optical cable installed underground as a sensor to analyze vibration. It demonstrated the world’s first example of making decisions
from a distant location regarding snow removal in aheavy snowfall area. It showed the prospects forusing optical fiber installed in many areas around theworld for more than just communication and to contribute to solutions for various regional issues byusing it as infrastructure for environment maintenance (Fig. 8).
(3)	Hyperspectral analysis technology for different
views of reality
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To understand the world beyond the human perception, the “Hyperspectral analysis technology for different views of reality” exhibit introduced a technology that changes coloring and makes predictions
from images captured with a hyperspectral camera.
The exhibit showed the potential for giving additional value to earlier images and video by visualizing information that cannot be captured by the humaneye. The live demo also showed the case of using it in
the entertainment field, by shining light over a wide
area on the clothing at the 2023 Paris Collection tochange the appearance of color in the clothing(Fig. 9). The neighboring exhibit, “Hyperspectral
imaging with a metalens and AI,” displayed an example of visualizing the sweet parts of fruit by overlaying visual information on sugar content over imagesof the fruit (Fig. 10), and introduced many application examples. By accurately visualizing various
colors captured in hyperspectral images, various
visual representations and communication of information should be possible using color.
(4)	XR Sports space generation to reproduce thereal world’s experience“XR Sports space generation to reproduce the real97

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Fig. 9. Hyperspectral analysis technology for different views of reality.

Fig. 10. Hyperspectral imaging with a metalens and AI.

Fig. 11. XR Sports space generation to reproduce the real world’s experience.

world’s experience” exhibited technologies to perceive virtual space with all five senses, and not justvision. It presented “XR Sports Space” technology,
which is an ultra-realistic meta-based space that provides a realistic virtual sports experience using timechange, sound, vibration, and other information(Fig. 11). Also presented was a dynamic demonstration that attracted much attention, introducing thefeeling of participating in a bicycle race using technology that reproduces video, audio, and tactile sensation just like actually being there (Fig. 12). ThisNTT Technical Review

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brings us closer to a world in which viewers canparticipate in an international tournament being held
in a far-away place and “race” with the contestants inreal time.
5.4 IOWN Future
Exhibits in “IOWN Future” introduced initiatives
related to improving well-being for people in society
and developing new solutions to large scale social
issues at a global level with NTT technologies.
(1) Artificial photosynthesis
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Fig. 12. Bicycle race demo exhibit using space reproduction technology.

Fig. 13. Artificial photosynthesis.

Fig. 14. Artificial photosynthesis presentation demo.

Achieving carbon neutrality has become a global
issue and “Artificial Photosynthesis” exhibits someR&D focusing on the workings of plants as theygrow. It exhibited a technology being developed toreduce CO2 using “high-quality semiconductor photocatalysts,” one of NTT’s strengths, by adding aprotective layer to suppress deterioration (Fig. 13).
This technology has enabled NTT to achieve worldclass performance, with “continuous operation of
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more than several hundred hours.” The exhibit introduced conditions producing real photosynthesis andgenerated much excitement and anticipation for
implementation (Fig. 14).
(2) IOWN and future car
There is a range of initiatives and R&D being conducted around the world on automobiles and some ofthis R&D is looking to the future. The “IOWN andfuture car” exhibit featured applications of IOWN
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Fig. 15. IOWN and future car.

optical transmission technology, opto-electric integration technology, and computing. These will beessential in realizing “future cars” as they are being
discussed at the IOWN Global Forum, to solve social
issues and also to increase well-being. Of course they
will realize a safer, more-enjoyable in-car space
while fully utilizing information from cameras andsensors in all directions to ensure safe and secure
driving, but they will also be equipped with moreadvanced features using generative AI and low-energy computing, so that vehicles will evolve from being
just a means of transport into a “lifestyle support
partner” for a comfortable and sustainable future.
This exhibit also attracted much attention (Fig. 15).

6. Conclusion
During this Forum, we have introduced R&D being
promoted by NTT, highlighting the steady progress
toward implementation of IOWN, and new potential
created by technologies such as IOWN and tsuzumi,
NTT’s LLM. We hope that our many visitors havegained a real sense of NTT’s latest technologies andfuture prospects, as well as the vision for the futurethat we are co-creating with our various partners.
NTT will continue working to create a rich future forpeople and the planet, meeting new challenges andcontinuously innovating. We hope you will continue
to look forward to IOWN and other NTT R&D as it
accelerates in the future.

Members of NTT R&D Forum Secretariat: (from left in theback row) Atsushi Ikeda, Masakatsu Fujiwara, Tetsuya
Ooishi, Hiroyuki Shiba, Kei Karasawa; (from left in the frontrow) Yoshifumi Shiraki, Masaki Hyodo, Shunsuke Mori,
Tokinobu Mitasaki, Tomoki Baba, Hironari Yokoi, Takanori
Watanabe, Keita Takahashi

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External Awards
IPSJ Contribution Award
Winner: Katsumi Takahashi, NTT Social Informatics Laboratories
Date: June 1, 2023
Organization: Information Processing Society of Japan (IPSJ)For contribution to the technology and legal system of data security and privacy.
3rd place at iPWS Cup 2023
Winners: Takayuki Miura, NTT Social Informatics Laboratories;
Masanobu Kii, NTT Social Informatics Laboratories; Atsunori
Ichikawa, NTT Social Informatics Laboratories; Juko Yamamoto,
NTT Social Informatics Laboratories
Date: August 28, 2023
Organization: iPWS Cup Committee, International Workshop on
Security (IWSEC) 2023
Won 3rd place overall at iPWS Cup 2023, a data anonymizationcompetition held at IWSEC 2023.
Outstanding Paper Award
Winners: Naoki Azuma, Nihon University; Toshiki Onishi, Nihon
University; Shunichi Kinoshita, Nihon University; Ryo Ishii, NTT
Human Informatics Laboratories; Atsushi Fukayama, NTT Human
Informatics Laboratories; Takao Nakamura, NTT Human Informatics Laboratories; Akihiro Miyata, Nihon University
Date: September 19, 2023
Organization: IPSJ/Multimedia, Distributed, Cooperative, andMobile Symposium (DICOMO) 2023
For “A Study on Prediction of Listener’s Various Backchannels
Based on Multimodal Information.”
Published as: N. Azuma, T. Onishi, S. Kinoshita, R. Ishii, A. Fukayama,
T. Nakamura, and A. Miyata, “A Study on Prediction of Listener’s
Various Backchannels Based on Multimodal Information,” Proc. of
DICOMO 2023, 3A-2, Toyama, Japan, July 2023.
2nd place at PWS Cup 2023
Winners: Tomoya Matsumoto, Osaka University; Yumeki Goto,
Osaka University; Hiroki Tejima, Osaka University; Takayuki Miura,
NTT Social Informatics Laboratories; Issa Sugiura, Osaka University
Date: November 1, 2023
Organization: 9th Privacy Workshop (PWS 2023)
Won 2nd place overall (3rd place in anonymization and 2nd place
in attribute estimation) at PWS Cup 2023, a data anonymization andattribute estimation competition held at PWS 2023.
ACC Finalist in Creative Innovation Category, ACC TOKYOCREATIVITY AWARDS
Winners: Tatsuya Kako, NTT Computer and Data Science Laboratories; Hironobu Chiba, NTT Computer and Data Science Laboratories; Akira Nakayama, NTT Computer and Data Science Laboratories; Kenichi Noguchi, NTT Computer and Data Science Laboratories; Shoichiro Saito, NTT Computer and Data Science Laboratories;
Hiroshi Sakai, NTT Sonority, Inc.; Jun Iwase, NTT Sonority, Inc.;
Hiroaki Sato, NTT Sonority, Inc.; Yoichiro Kakiyama, NTT Sonority,
Inc.; Kenta Yamada, NTT Sonority, Inc.; Chihiro Sasaki, NTT Sonor-

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Vol. 22 No. 3 Mar. 2024

ity, Inc.; Yoshiaki Kozaki, NTT Sonority, Inc.; Tsukasa Kumagai,
NTT Sonority, Inc.; Koichi Sugiura, NTT Sonority, Inc.; Itaru Sugita,
NTT Sonority, Inc.; Kazunori Kobayashi, NTT Sonority, Inc.; Shintaro
Takeuchi, NTT Sonority, Inc.
Date: November 2, 2023
Organization: All Japan Confederation of Creativity (ACC)
For research and development of nwm MWE001 open ear earphone that reduces sound leakage.
ICETC 2023 Best Poster Award
Winner: Jumpei Hayakawa, NTT Access Network Service Systems
Laboratories
Date: November 30, 2023
Organization: The Institute of Electronics, Information and Communication Engineers (IEICE) Communications Society
For “Simple Method for Measuring Spatial Mode Dispersion in
Coupled Multi-Core Fibers without Accessing Both Ends.”
Published as: J. Hayakawa, A. Nakamura, M. Nakamori, and Y.
Koshikiya, “Simple Method for Measuring Spatial Mode Dispersion
in Coupled Multi-Core Fibers without Accessing Both Ends,” International Conference on Emerging Technologies for Communications(ICETC) 2023, P1-10, Sapporo, Japan, Nov./Dec. 2023.
Fellow
Winner: Yoji Yamato, NTT Network Service Systems Laboratories
Date: December 11, 2023
Organization: IEICE
For research and practical application of the advanced open source
cloud.
Honorable mention
Winner: Team NTT-EASE (Yuki Kubo, NTT Social Informatics
Laboratories; Tomoya Yamashita, NTT Social Informatics Laboratories; Masanori Yamada, NTT Social Informatics Laboratories)
Date: December 23, 2023
Organization: Dialogue Robot Competition (DRC) 2023
For “Dialogue System of Team NTT-EASE for DRC2023.”
Published as: Y. Kubo, T. Yamashita, and M. Yamada, “Dialogue
System of Team NTT-EASE for DRC2023,” arXiv:2312.13734,
2023.
OFT Young Researcher’s Award
Winner: Ryota Imada, NTT Access Network Service Systems Laboratories
Date: January 11, 2024
Organization: IEICE Technical Committee on Optical Fiber Technologies (OFT)For “A Study on Bending Loss Property of Coupled Multicore
Fiber.”
Published as: R. Imada, T. Sakamoto, T. Mori, Y. Yamada, and K.
Nakajima, “A Study on Bending Loss Property of Coupled Multicore
Fiber,” OFT2022-58, 2023.

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Papers Published in Technical Journals andConference Proceedings
Catalytic Transformation from Computationally-universal
to Strictly-universal Measurement-based Quantum Computation
Y. Takeuchi
arXiv:2312.16433, December 2023.
There exist two types of universality in measurement-based quantum computation (MBQC): strict and computational universalities. It
is well known that the former is stronger than the latter. In this paper,
we give a method of transforming from a certain type of computationally-universal MBQC to the strictly-universal one. Our method
simply replaces a single qubit in a resource state with a Pauli-Y
eigenstate. We apply our method to show that hypergraph states canbe made strictly universal with only Pauli measurements, while only
computationally-universal hypergraph states were known so far.

Blind and Spatially-regularized Online Joint Optimizationof Source Separation, Dereverberation, and Noise Reduction
T. Ueda, T. Nakatani, R. Ikeshita, K. Kinoshita, S. Araki, and S.
MakinoIEEE ACM Trans. Audio Speech Lang. Process., Vol. 32, pp.
1157–1172, January 2024.
This paper proposes a computationally efficient joint optimization

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Vol. 22 No. 3 Mar. 2024

algorithm that performs online source separation, dereverberation,and noise reduction based on blind and spatially-regularized processing. When applying such online Blind Source Separation (BSS) as
online Independent Vector Extraction (IVE) to a speech application,
we must focus on the trade-off between the algorithmic delay andseparation accuracy, both of which depend on the analysis frame
length. In addition, to separate the sources with specified source
permutation, researchers introduced spatial regularization based on
the Directions-of-Arrival (DOAs) of the sources into IVE. However,the scale ambiguity of IVE often makes the spatial regularization
work inappropriately. To solve these problems, we first propose ablind online joint optimization algorithm of IVE and weighted prediction error dereverberation (WPE). This online algorithm canachieve accurate separation even using short analysis frames because
reverberation can be reduced using WPE. We then extend the online
joint optimization with robust spatial regularization. We reveal that
regularizing the scale of the separated signals is very effective inmaking the DOA-based spatial regularization work reliably. Our
experiments confirm that our blind online joint optimization algorithm can significantly improve the separation accuracy with analgorithmic delay of 8 ms. In addition, we confirm that the proposed
spatially-regularized online joint optimization algorithm reduces therate of the source permutation error to zero percent.

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