NTT Technical Review

February 2022 Vol. 20 No. 2

Front-line Researchers Akira Fujiwara, Senior Distinguished Researcher, NTT Basic Research Laboratories
Rising Researchers Kim Sangyuep, Distinguished Researcher, NTT Access Network Service Systems Laboratories
Feature Articles: Keynote Speeches at NTT R&D Forum—Road to IOWN 2021
 Jun Sawada, President and Chief Executive Officer, NTT Katsuhiko Kawazoe, Executive Vice President, Head of Research and Development Planning
Department, NTT
Feature Articles: 2021 International Sporting Event and NTT R&D—Technologies for
Supporting Athletes Women’s Softball × Sports Brain Science Cycling × hitoeTM: Dialogue with the Body via Surface Myoelectric Potentials
 Swimming × Online Coaching: Online Conditioning of Competitive Swimmers—Focusing on
the Thorax—via Smartphones and Wearable Sensors
Feature Articles: 2021 International Sporting Event and NTT R&D—Technologies for
Preparing the Event Network Construction × Wearable Heat Countermeasures Venue-management Staff × CUzo
Feature Articles: 2021 International Sporting Event and NTT R&D—Technologies for
Making the Event Inclusive
 Barrier-free Route Guidance × MaPiece®
 Goalball × Ultra-realistic Communication Technology Kirari!
Global Standardization Activities
 Recent Activities of ITU-R Study Group 5 on Terrestrial Radiocommunication Systems
Practical Field Information about Telecommunication Technologies
 Impact of Wildlife on Access Network Facilities—Problems Caused by Monkeys andCountermeasures against Them
Information
 Report on NTT R&D Forum—Road to IOWN 2021
External Awards/Papers Published in Technical Journals and Conference Proceedings

Front-line Researchers

Even If Facing Difficulties, Create
New Value While Building on the
Achievements of Your Predecessors
Akira Fujiwara
Senior Distinguished Researcher,
NTT Basic Research Laboratories
Abstract
The missions of NTT Basic Research Laboratories are to promote advances in science that will ultimately benefit humankind
and contribute to NTT’s business. Researchers at the laboratories
have published numerous achievements in the fields of materials
science, physical science, and optical science. Akira Fujiwara, asenior distinguished researcher, is researching silicon singleelectron devices to enable accurate operation and detection of
single electrons, which are expected to be applied to quantum
electrical standards, high-sensitivity sensors, and quantum qubits.
We asked him about the progress of his research activities andattitude as a leading researcher.
Keywords: silicon single-electron device, electric-current standard, quantum metrology triangle

Taking the challenge of applying silicon
single-electron devices to high-accuracy
electric-current standards—Could you give an overview of your current
research for the readers?
My current research is focused on (i) developing
ultimate electronics on the basis of high-precisionand high-speed charge manipulation, detection, andcontrol of electrons using silicon-based semiconductor nanodevices and (ii) applying this technology tohigh-accuracy electric-current standards, ultra-lowenergy information processing, ultra-sensitive sensing, and quantum technology (Fig. 1).
Computers and smartphones, which have become
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Vol. 20 No. 2 Feb. 2022

everyday tools, use semiconductor circuits made ofsilicon. By passing an electric current through a semiconductor circuit or applying a voltage across it, thecurrent can be amplified or switched on/off. The current flowing through the semiconductor circuit consists of moving electrons, which are tiny particles
with a negative charge. In my research, I am testing
the limits of how far we can control and manipulate
each electron in a silicon semiconductor. Such control and manipulation of single electrons will beapplicable to ultra-low-energy information processing and ultra-sensitive sensing. Units such as themeter (m) for length and kilogram (kg) for mass aredefined as basic international standards for weights
and measures. Regarding the ampere (A), which is
the unit for electric current, we are aiming to establish
1

Front-line Researchers

Quantum electrical standards
Electric-current standards
Quantum metrology triangle

High-sensitivity sensor
Single-electron detection
Ion and molecule detection

Silicon nanowire
Low-energy
information
processing

Quantum information processing
and quantum sensing
Quantum bit
Electron quantum optics

Fig. 1. Ultimate electronics using silicon nanodevices.

a quantum electrical standard on the basis of an accurate current generated by a silicon single-electron
device.
—What triggered you to target a new international
standard for electric current?
In 2003, when I was a visiting researcher at the
National Institute of Standards and Technology(NIST, Gaithersburg, USA) and evaluating the characteristics of a silicon single-electron device developed by NTT, I realized that the field of standards—
which pursues extreme accuracy—is the most suitable application of the device. After ten years of persistent research, I began to receive interest from
Europe as well.
The technology I am pursuing was not adopted
when the International System of Units (SI) was
revised in 2019 as well as the definition of theampere. However, believing that it will be adopted in
the future, I am continuing my research while working hard with researchers around the world. Being
recognized for such efforts, I was honored to be elevated to an IEEE (Institute of Electrical and Electronics Engineers) Fellow in 2018 and JSAP (Japan
Society of Applied Physics) Fellow in 2020. I am gladthat I did not give up on my research.
I am currently working on establishing high-accuracy single-electron current standards and achieving
the quantum metrology triangle, which is an experiment to verify the consistency of quantum electricalstandards. Specifically, I am working on (i) the charNTT Technical Review

Vol. 20 No. 2 Feb. 2022

acteristic evaluation of devices fabricated at NTT
using a semiconductor-manufacturing line forresearch purposes and (ii) computational analysis ofsuch devices using a device simulator, which wedeveloped when we were teleworking during thenovel coronavirus pandemic (Fig. 2). Following therevision of the definition of the ampere in 2019, electric current is now defined as the number of electrons
that constitute the current carried per second, and weare currently focusing on how to transfer one electron
accurately and quickly while minimizing as mucherror as possible. Silicon single-electron devices also
have the potential to be applied to quantum computers, which is a hot topic of research; however, it isvery difficult to produce many identical devices
because of their extremely small size. Therefore, I
believe that it is important for us to focus on applying
such a device in electric-current standards in which
one device will be good enough to demonstrate its
usefulness.
Collaboration is a vital part of this research. Aboutfive years ago, we issued a press release about theresults of our joint research with the National Physical Laboratory (NPL) in the UK, announcing that we
could generate accurate currents at the world’s fastest
operating speed [1]. We have also begun joint
research with the National Institute of Advanced
Industrial Science and Technology (AIST), which
manages Japan’s national standards.
For practical use of a high-accuracy current standard that will enable the revised “new ampere,” wewill have to further improve the accuracy of the26

Radial distance from centerof silicon nanowire (nm)

Front-line Researchers

e: elementary charge
f : clock frequency

4

−200

−100

0

100

200

100

200

3.0

3
2
1
0
−1000

−800

−600

Gate voltage (mV)

Potential energy (eV)Electric current (ef )

5

140
120
100
80
60
40
20
0

2.5
2.0
1.5
1.0

Electron

0.5
0.0
−0.5
−200

−100

0

Axial position of silicon nanowire (nm)Fig. 2. C haracteristics of silicon single-electron current standards (experimental results) and potential analysis using adevice simulator.

currents generated by a silicon single-electron device.
To break the world record and take the global lead, we
are working with AIST and other teams to complete
the quantum metrology triangle using single-electron
current standards.
Verify your research fairly—Is it important for researchers to take up the challenge of being the best in the world?
Research, whether basic or applied, is carried out asa community, and in each community, many competitors aim to be the best in the world. I believe that
this situation is good for all because by competing
together, even if one of us loses, we can all learn.
Such friendly rivalry will lead to contributions to thefield as well as society. The development of theresearch community may lead to not only the commercialization and implementation of our products insociety but also the creation of new research themes
and business.
I sometimes naturally feel disappointed when I am
competing with overseas researchers. Although Japanis excellent in the field of science, the United Statesand Europe, the birthplace of modern science, areeven better and have more resources, including a
deeper pool of researchers. I even have moments
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when I feel that Japan is losing and accept that factwith humility, but I am also sometimes frustrated
with my lack of ability.
Under these circumstances, I try to evaluate andverify my own research fairly. For example, you canjudge the quality of your research results, their significance, and their contribution to the community by
the response from the community and leading
researchers. Of course, it is important to have yourown beliefs, but I try not to be complacent and evaluate myself objectively so that I can grow further.
I have been active as a researcher for a long timeand feel that the environment surrounding research is
becoming more difficult every year. In Europe andthe United States, the competition is very fierce, and
it is a tough environment in which you have to keep
producing outstanding results to survive under severe
competition for acquiring research funds and humanresources. In quite a few cases, people leave theirhome countries in search of a research environment
and place in which they can be themselves and live
their lives as researchers. China is producing goodresults with its large organizations and resources;even so, I have heard that in some cases, young
researchers are only allowed to work as research
assistants. Compared with those countries, Japan is agood environment for creating new ideas in a harmonious relationship among researchers but lacks the3Front-line Researchers

intensity as in other countries. Still, it is difficult toobtain employment as a researcher in Japan, and, as
has been reported in the media, it is also difficult foryoung researchers to find an academic post at a university.
Under these circumstances, the choice of a research
theme can be a fork in the road for researchers. For
example, research in a popular field is, in a sense,
secured by the fact that it is needed by society, so a
certain number of posts are available. Working on
research in such a field that is currently needed or
popular is one meaningful choice; however, you run
the risk of being carried away by superficial trends
and your research not becoming significant enough.
In the case of basic research, it is important to take amore long-term perspective and read the trends. If
you find a field in which you can use your strengths
or a theme that only you can tackle and has the potential to make you a leading researcher, you shouldcompete in that field, even if it is a narrow one.
I am conducting research on electric-current standards with this mindset, and striving to make the mostof my skills, one step at a time. For the rest of myresearch life, I want to pursue what only I can dowhile evaluating my research fairly from time to timeso that I do not become complacent.
—You have been pursuing the issues that will impact
future society rather than the issues facing us today,right?
Science is a process of knowledge accumulation, so
even if my research is not useful right now, I want to
conduct research that prompts people to say things
like, “This is really new.” and “This is one step forward.” I believe that it is very important to aim forresearch that is valued by the research community.
I think that my research has been successful tosome extent by having this attitude, therefore I cherish the research community and colleagues. If you
understand what has been done in the community by
your predecessors, you will come to respect them. If
you focus on adding something new to the community, the community will grow and the researchers
who belong to the community will be able to continue
their research, creating a virtuous cycle. It is important to build up the community and become a valued
member so that you can exchange useful informationand obtain the cooperation of other researchers. To
that end, I want to continue to engage in friendly
rivalry with world-class researchers. It is vital to havepeople around you with whom you can have serious
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discussions about your research and continue learning from the results of those discussions, and I am
happy to have such a community around me now. I
work in an environment in which I can form collaborative teams with my colleagues and have come torealize the importance of collaborative research.
I think that the culture of Japanese companies andthe mindset of researchers still have a strong tendency
to do everything on their own. Japanese researchers
have a strong respect for craftsmanship and are willing to do work with their hands in every aspect,
including everyday maintenance of experimental
equipment. Although I think that mindset is commendable, in Europe, the work of technicians is separate from that of researchers, and many companies
seem to think that what they don’t have in-house, they
can obtain from outside. Partly due to cultural differences, international companies are probably moreaccustomed to doing things collaboratively. Bothdomestic and international companies have advantages and disadvantages, but if you can produce goodresults and new value by complementing what you
don’t have with what others do have, I think joint
research is essential.
I used to be less than enthusiastic about collaborating. It was the advice from Tetsuomi Sogawa, head of
the NTT Science and Core Technology Laboratory
Group (who was then head of NTT Basic ResearchLaboratories), that changed my mind. Regarding thejoint research with NPL on electric-current standards
I mentioned earlier, he encouraged me to, “Not only
work within our lab but also collaborate with outside
parties to give your research a visible presence.” I am
also encouraging mid-career and young researchers
to follow that advice. Joint research involves a lot oftasks due to intellectual property issues and piles of
paperwork, but I transfer the necessary skills to theseresearchers and assure them that they can go ahead
and form collaborations without hesitation if theyneed to. That said, I try not to say too much or be tooforceful so as not to put too much pressure on our
young researchers; in other words, I just try to makesure that my advice is one of their options.
Research mottos: “friendly rivalry,” “takeadvantage of every opportunity,” and “dig deep”—What has been important to you in your research
activities?
I believe that basic research is not immediately useful or helpful to anyone; however, even if you face4

Front-line Researchersdifficulties, create something new and valuable whilebuilding on the achievements of your predecessors.
With that belief in mind, I continue my research
activities with the mottos of “friendly rivalry,” which
I have mentioned several times already, as well as“take advantage of every opportunity,” and “digdeep.” I believe that research is about learning fromyour failures, and even though I have had many failures, I have tried to learn from them. When I wasyoung, sometimes the devices I created did not work
as expected, but as I searched for the cause of the
problem, I discovered new phenomena. At that time,
I remember how happy I was when one of my seniorcolleagues said to me, “Mr. Fujiwara, even if you fall,
you get up and learn from your failure.”
Research is often described as “digging deep andwide.” It is important to dig deeper and deeper into
your topic. You need to understand more about the
topic than anyone else to come up with new ideas. It
is also very important to dig horizontally and cultivate the area surrounding your research topic. Doingso will help you understand the position of theresearch you are working on, and you will learn thatit actually has a close relationship with unknown
fields. That’s why I often tell young researchers totake both approaches. If you only dig deep, you will
become complacent, and if you only dig horizontally,
you will end up with research without depth. I’m also
trying to find a good balance between digging deep
and digging horizontally.

is try to get people to remember your face. It is also
important to ask questions and make impactful presentations at international conferences. When you get
the opportunity to make a presentation, I hope you
will practice hard and impress the audience in such amanner that they will think, “What an impressive
young person!”If you feel uncomfortable asking a leading researcher a question, ask a talented person of your generation
first or someone who is more approachable. In thatsense, coffee breaks at a conference are valuable
times to meet and ask questions. In fact, quite important information about research is exchanged at suchmeetings, so don’t drink coffee alone because you are
tired; instead, listen to the detailed stories that you
couldn’t hear at the presentations and the stories
about the presenters’ difficulties. All top researchers
have such lively exchanges of information during
coffee breaks.
At times, I feel that I am not yet part of that circle,
even though I am saying things that sound great. At
other times, I find it difficult having conversations
with native speakers of English and feel that I am stillin the process of learning. Therefore, let’s take thechallenge and get into such conversations without
hesitation. You tend to be hesitant if you think you’re
not good enough or don’t understand what’s being
said. Well, that’s just the way I am. Instead of hesitating, it’s okay to say, “I don’t really understand the
topic, but may I join the conversation anyway?” You
don’t have to pretend to know more than you do.

—Finally, do you have any advice for young researchers on how to interact with leading researchers?
I think it is quite intimidating for a young researcher to suddenly meet a “big name” in their field. It may
sound like a cliché, but the first thing you should do

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Reference[1]

Press release issued by NTT, “World-record accuracy of gigahertz
high-speed single-electron transfer – An important step toward a highaccuracy current standard –,” July 5, 2016.
https://group.ntt/en/newsrelease/2016/07/05/160705a.html

5Front-line Researchers

Interviewee profile
Akira Fujiwara received a B.E., M.E., andPh.D. in applied physics from The University ofTokyo in 1989, 1991, and 1994. He joined NTT
LSI Laboratories in 1994 and moved to NTT
Basic Research Laboratories in 1996. Since 1994,
he has been engaged in research on silicon nanostructures and their application to single-electron
devices. He was a guest researcher at the National
Institute of Standards and Technology (NIST),
Gaithersburg, MD, USA from 2003 to 2004. He
was a director of the Japanese Society of Applied
Physics (JSAP) in 2010 and 2011 and a visiting
professor of Hokkaido University in 2013. He
was appointed as a distinguished scientist of NTT
in 2007 and senior distinguished scientist of NTT
in 2015. He received the International Conference
on Solid State Devices and Materials (SSDM)
Young Researcher Award in 1998, SSDM Paper
Award in 1999, and Japanese Journal of Applied
Physics (JJAP) Paper Awards in 2003, 2006, and2013. He was awarded the Young Scientist Awardin 2006 and Prizes for Science and Technology in2017 from the Minister of the Ministry of
Education, Culture, Sports, Science, andTechnology. He was supported by the funding
program for Next Generation World-Leading
Researchers (NEXT Program), Japan Society for
the Promotion of Science (JSPS) from 2011 to
2014. He is now a principal investigator of the
2018–2022 JSPS KAKENHI S (Quantum
Standards and Ultimate Precision Measurements
Based on Single Electrons). He is a JSAP Fellow,
a member of Science Council of Japan, and an
IEEE Fellow.

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6

Rising Researchers

Research into Ultra-high-speed
Full Software Access Networks
that Virtualize the Physical Layer
Functionality of Communications
Networks
Kim Sangyuep
Distinguished Researcher, NTT AccessNetwork Service Systems Laboratories
Abstract
Virtualization is progressing in a variety of areas, including
networking, servers, and storage. In this issue, we speak with
Distinguished Researcher Kim Sangyuep about the virtualizationof the physical functionality (high-speed transmission interfaces)of communications networks, something which is very difficult to
do with conventional technologies.
Keywords: virtualization, softwarization, logic algorithms

Aiming to provide flexible services without beingtied to dedicated hardware—What exactly does research into ultra-high-speed
full software access networks entail?
The optical access lines we have today need to provide services to user devices that each has different
requirements when it comes to communications
speed, latency, security, and so forth. What’s more,communications traffic rapidly increases as thoseservices become more sophisticated and complex. In
order to meet these requirements, each service provider uses access devices that consist of dedicateddevices such as large-scale integration (LSI) andapplication-specific integrated circuits (ASICs) thatNTT Technical Review

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are customized to the service’s specifications.
However, there are also some drawbacks to using
hardware based on these dedicated devices (i.e.,
dedicated hardware). First of all, the nature of dedicated hardware is such that once it has been manufactured and implemented, its functionality cannot bechanged. This makes it difficult to respond flexibly toadditions or changes to the service, and tends to make
operation and maintenance tasks awkward.
We therefore expect to see software-based networks become a reality. These are networks where
the functions of all the constituent devices are softwarized and can be freely combined on servers andoffered as services. This would allow quick responses
to security emergencies, as hardware changes would
not be required when new services are needed, and7

Rising Researchers

The future

Current situation

Softwarization of conventional hardware access devices,
including physical layer functions• Deliver services by combining compartment-based functions.
• Latest functions are always available for use.

Use of specialized hardware such as LSIs, ASICs, etc.
• Functionality is difficult to change.
• Operation and maintenance are often awkward.
OLT

Physical Bandwidth
functions control

OAM

MulticastLatest functions
are always
available
for use.

Newfunctions

General-purpose
hardware• Functional block
configuration
based on vendor’s
proprietaryarchitecture

ONU
ONU

ONU

Service-specificimplementation

Softwarization of
conventional hardware
access devices,
including physicalfunctions

External
hardwaremoduleDelivering services bycombining componentbased functional blocks
ONU
ONU

ONU

OAM: operations, administration, maintenance
ONU: optical network unit

Fig. 1. Research into ultra-high-speed full software access networks.

the latest functionality would always be available. If
software-based networks become a reality, they will
enable support for a variety of services, such as services for next-generation mobile devices, edge computing, and the Internet of Things.
To achieve this, I have been focusing on the softwarization of the physical layer functionality of communications networks—something that has typicallyposed a challenge. I am currently working on research
into the full softwarization of the physical layer—inother words, the transmission interface—that performs the lower-layer processing in optical accessequipment that has so far been handled by hardware
such as optical line terminals (OLTs). To put it more
technically, I am working on the softwarization ofdigital coherent modulation and demodulation systems.
I am planning to use general-purpose server central
processing units (CPUs), graphics processing units(GPUs), and other processors to handle these processes using programming, coding, and other techniques (Fig. 1).
—What are the challenges of softwarization?
When you take into account 6G (sixth-generation
mobile communications system), the mobile communications standard that will succeed 5G (fifth-generation mobile communications system), and future
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communications between datacenters, we will eventually end up needing overwhelming speeds of 100
Gbit/s. However, increasing speeds using generalpurpose processors is very challenging due to fundamental limitations, such as constraints in the semiconductor manufacturing process.
There are already fully softwarized networks, but
their speeds are still only at about 100 Mbit/s at present. That’s a mere 1/1000th of the 100 Gbit/s I am
aiming for—quite an astounding difference in speeds.
Therefore, in this research I am trying to overcome
this problem by focusing on devising logic algorithms optimized for general-purpose processors
such as CPUs, coprocessors, GPUs, and field programmable gate arrays (FPGAs). Increasing the
speed is potentially the biggest challenge in making
software-based networks a reality in the future.
—What progress has been made to date?
In 2018, a proof of concept of a software-coherent
platform using differential phase shift keying
achieved a world-first 5 Gbit/s, and was accepted as a
top-scoring paper at the Optical Fiber Communication (OFC) Conference, a prestigious international
conference in the field of optical communications.
In 2021, another world-first speed of 10 Gbit/s wasachieved—double that achieved in 2018—using aproprietary carrier phase-locking algorithm. This
8

Rising Researchers

ServerCPU

OS (CentOS) / Application (GPU kernel: coherent receiver DSP algorithm)

I
Analogcoherent
optic (ACO)
coherent Rx

FMC+
ADC
80
Gbit/sQ

GPU

General-purpose hardware
FireFly

I/O(master)

40 Gbit/s

ADC: analog-to-digital converter
DSP: digital signal processor
FMC: FPGA Mezzanine Card

I/O
(slave)I/O(output)

GPU

CPU

I/O
(10 Gbit/s)

40 Gbit/s

90 Gbit/s

Direct data transfer

Transfer control

I/O(80 Gbit/s)

10 Gbit/s

ADC
PCle bus

I/O: input and output
OS: operating system
Rx: receiverFig. 2. 10-Gbit/s software-coherent platform.

accomplishment was also presented in a paper at theEuropean Conference on Optical Communication, asimilarly prestigious international conference in thefield of optical communications.
This increase in communications speed from 5
Gbit/s to 10 Gbit/s is mainly due to improvements inlogic algorithms. Increasing the bit rate, or communications speed, naturally increases the amount of datatransmitted per unit of time. For example, the amountof data per unit of time doubles with an increase from
5 Gbit/s to 10 Gbit/s. First, that doubled data have to
be input to the server and processed by the CPU,
GPU, and other processors. There are already established logic algorithms for data processing, but as thevolume of data increases, real-time processing is nolonger able to keep up. This is why logic algorithms
have so far been optimized for CPUs and GPUs inorder to increase speed. If we express the target of
100 Gbit/s as 100%, then we can say that at this point
we have achieved about 10% of this target (Fig. 2).
Aiming to develop software-based accessnetworks in the future—What outcomes could this research produce?
Communications services have evolved from Integrated Services Digital Network to asymmetric digital subscriber lines, and then to optical access (fiber
to the home). Communications speeds have also
evolved—from 100 Mbit/s to 1 Gbit/s, and then toservices reaching 10 Gbit/s in 2020. In the mobile
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field in particular, the focus of the discussion is shifting from 5G to 6G, and I feel that the role of accesssegment communications—the foundation that supports these technologies—is growing. This research
will likely prove beneficial in creating mechanismsthat adapt flexibly to and provide support in this area.
In addition, relatively inexpensive general-purpose
hardware will become able to support a variety of
future service requirements, such as for high-speed
wired optical communications and next-generation
mobile communications. This will dramatically
expand the diversity and flexibility of optical accessand is anticipated to reduce equipment installation,
operation, and maintenance costs. There are still
many hurdles to overcome in terms of practical use,
but I believe this will contribute to the Innovative
Optical and Wireless Network (IOWN) vision, which
I expect to see implemented in society in the future.
—Can you tell us about future developments in thisresearch?
The approach of this research is to optimize software algorithms to increase speeds. However, the key
focus of this is creating new algorithms to improve
speeds, rather than improving current algorithms. I
hope to make new breakthroughs and achieve ourtarget speed of 100 Gbit/s or faster. Furthermore, byintegrating the softwarized physical layer with theapplication layer, I intend to build a new ecosystemthat will increase the number of my fellow collaborators from different fields and industries.
9

Rising Researchers—What kind of initiatives will be needed to further
advance this research?
I hope to advance this research effectively throughthe establishment of strategic collaboration frameworks with advanced research organizations in relevant fields. General-purpose processors, of course,
have inferior performance compared to that of processors customized for a specific function. However,they do offer advantages such as flexibility, so there
will surely be a need for algorithms that are tailoredto suit them. For this reason, it would certainly bebeneficial to work with people who have a goodknowledge of general-purpose processors.
In addition, this research requires not only digitalprogramming skills, but also knowledge of electricalcircuits, server hardware, and a variety of otherthings, so I also envision establishing strategic collaboration frameworks with companies that develop
server hardware. I know Japanese companies havebeen developing server-related hardware for years
with an extremely high level of focus, so I hope to beof use in that area, as well as accelerating myresearch. For example, I can envision working together with businesses that develop hardware, software,and other solutions for datacenters. It will also be
possible to integrate applications into the softwarized

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physical layer, which could be beneficial for connecting with businesses that develop and provide services.
Furthermore, as data transfer speeds increase, so too
does the need for large volumes of data to be sent
within the server. That being the case, it would begood if I could establish collaboration frameworks
with anyone familiar with data transfer, i.e., speeding
up interfaces such as Peripheral Component Interconnect and transferring data to the server’s memory.

Interviewee profile
Kim Sangyuep joined NTT in January 2008,
where he has been engaged in research into ultrahigh-speed full software access networks at NTT
Access Network Service Systems Laboratories.
He received the Best Paper Award in Selected
Areas in the Communications Access Networks
and Systems Track at the 2016 IEEE Global
Communications Conference (GLOBECOM).
He was a subcommittee member of the
Optoelectronics and Communications Conference(OECC) 2018 and has been a subcommittee
member of the OFC Conference and Exhibition
for 2020–2022.

10

Feature Articles: Keynote Speeches at NTT R&D
Forum—Road to IOWN 2021

What is IOWN?
Jun Sawada
President and Chief Executive Officer,
NTT
Abstract

This article introduces initiatives to expand the use of the Innovative
Optical and Wireless Network (IOWN) called the “Road to IOWN.” It isbased on the keynote speech given by Jun Sawada, president and chief
executive officer of NTT, at the “NTT R&D Forum—Road to IOWN
2021” held from November 16th to 19th, 2021.
Keywords: IOWN, All-Photonics Network, bio digital twin

1. Road to IOWN
Let me today introduce our initiatives to expand theuse of the Innovative Optical and Wireless Network(IOWN) called the “Road to IOWN.” Before that, I
would like to reflect on recent natural disasters,
which have become much more severe than in thepast. In the summer of 2021, a disastrous landslide
occurred in Atami City, Shizuoka Prefecture in Japan,
and in Germany, about 200 people died in torrential
rains and floods. There were also the earthquake in
Haiti and wildfires in California. On top of all that,the threat of the novel coronavirus (COVID-19) pandemic has changed our lives dramatically over thelast two years.
The pandemic has made remote work (work fromhome) more widespread and has made it difficult forpeople to meet in person. Along with the world
becoming more connected through the Internet, problems such as crimes related to the Internet and overflow of information with varying quality called “infodemic” have been increasing. From a different viewpoint, a lesson learned from natural disasters andpandemics is, “Nature is full of unexpected things.”
We should be aware that unexpected things are happening all the time and are out of our control. Therefore, what conclusions can be reached when the situation is so unexpected and uncontrollable? The
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means of trying to explain the world using naturalscience is called “naturalism.” As the idea of naturalism alone cannot deal with natural disasters, it isnecessary to take a broader view of preparation that
goes beyond what is scientifically understood.
The world cannot be explained by logic alone.
Jakob von Uexküll, a German biologist and philosopher, thought about this problem in a different way
and came up with the concept of the “umwelt” (“environment” or “self-centered world” in English)(Fig. 1). Umwelt may not have received much attention in current academic circles. However, we mayneed to apply this concept of umwelt when we think
about unexpected things as the scale of natural

HumanumweltNonhumanumwelten: Area of information processing
For a more natural state(creation of a more natural world)

Fig. 1. H uman umwelt—Enlarge areas of information
processing.

11

Feature Articles

Hemodynamics
model(electrical representation)

Simulation ofcardiopulmonary state

3D modeling (future image)Fig. 2. Bio digital twin.

disasters is increasing and people tend to be more easily divided due to the development of social networking services (SNSs), etc. By applying this concept tothe direction in which technology should advance, we
aim to expand the area in the human umwelt occupied
by information processing, which is currently verysmall. In other words, the goal is to achieve a situation closer to nature. For example, broadband enables
high-speed, high-capacity data transmission. This
technology is based on the idea of recreating a situation close to nature. Meanwhile, our communication
devices have evolved from fixed-line telephones tosmartphones, and at each evolution, we need to learn
how to use new devices, which results in putting loadon humans. This situation is far from natural. Technology, which can naturally support the human desire
to communicate and convey our thoughts, will leadour world to greater happiness.
2. Bio digital twin
Researchers at NTT Research, Inc. in the UnitedStates are working on reproducing the physical andpsychological states of humans in cyberspace(Fig. 2). They are currently focusing on modeling theheart. This research will support treatment based on
predictions by modeling and simulating hemodynamics from blood-flow data and visualizing the cardiopulmonary state. They have also started contributing
to preventive medicine for illnesses such as heartdisease and failure. Bio digital twin is another example for making information processing closer tonature.

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2.1 Using non-human umwelten
The world perceived by humans with our fivesenses, or six senses, differs from that perceived by
insects, fish, animals, and other organisms. As I mentioned in the previous NTT R&D Forum, birds andbees see things in ultraviolet light, while humans do
so in visible light. If we could see things in ultraviolet
light, a whole new world would be opened up. That is
to say, we would make our world closer to nature.
For example, dolphins emit ultrasonic waves (at afrequency of about 150 kHz) by shaking folds at theback of their throat near their vocal cords, while
humans can only hear sounds up to about 20 kHz.
This means that dolphins can communicate via veryhigh-frequency sounds compared with humans. Dolphins also have a bump on their forehead called the“melon organ,” which has a mechanism for effectively transmitting and receiving ultrasonic waves inthe targeted direction. While humans do not havesuch a mechanism, NTT laboratories developed amethod of listening to music and other sounds called
the “personalized sound zone” by using the mechanisms, technologies, and principles inspired fromdolphins. We established a company called NTT
sonority, Inc. in September 2021 and are currently
developing new products. Turning space into information to make people more comfortable will
improve well-being and bring information from adifferent umwelt to that of humans.
While the umwelt is traditionally characterized by
species, human communities are more than ever characterized by only information they are comfortablewith as we now live in a divided world. That is, we are12Feature Articles

Digital Twin
Computing
Cloud

Ctrl

API

Ctrl Operator A

API

Ctrl

API

API

Ctrl

Edge

Mobile network

Fixed network
Ctrl

Operator B

Ctrl

Operator C

Ctrl

Operator D

API

Multi-orchestrator

Cognitive
Foundation®

All-Photonics Network

API: application programming interface
Ctrl: controller

Fig. 3. IOWN framework.

entering an era of fragmentation, in which several
umwelten are created in human communities. We
need to figure out how to connect them, and I believethat the Innovative Optical and Wireless Network(IOWN) will be the medium to connect each umwelt
to make information processing in the human umwelt
closer to nature, apply the mechanisms of non-humanumwelten to the human umwelt, and close the communication gap between people.
3. All-Photonics Network
The framework of IOWN consists of three major
layers and four functions. The first layer is the AllPhotonics Network (Fig. 3). The idea behind the AllPhotonics Network is to use optical fiber across theentire network, replace the semiconductors that process information with optical technology, and use
optical computers. The All-Photonics Network will
support high-capacity, low-latency, and low-powerconsumption communication. A data-driven society
generates huge amounts of packets and information
data. The datacenters that store, transform, and process such data generate heat like a toaster and are
currently cooled inefficiently by using fans. Opticaltechnology will change this situation by reducing
heat generation drastically. Such technological revolution should bring about breakthrough innovations.
On top of the All-Photonics Network are the fixed
and mobile networks as the second layer, in which
many companies provide services around the world.
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Fifth-generation mobile communication networks(5G) are now being offered, and after that comes theera of 6G. The third layer is Digital Twin Computing.
In this layer, objects in real space are reproduced incyberspace such as a bio digital twin as described
previously. These three layers are connected via a
multi-orchestrator, and the entire structure is called
Cognitive Foundation®. We will live in a world inwhich various businesses will compete and cooperatewith each other, and Cognitive Foundation® will be
the key to promoting such competition. IOWN isformed by the elements of interconnection and interoperation. Several use cases of the All-Photonics
Network have started in 2021.
3.1 Avatar robot café DAWN Ver.β
I’ll introduce the comment by Yoshifumi Shiiba,
director and chief technology officer of OryLab Inc.
“DAWN is a café where people with physical disabilities can use the power of the Internet and technology to work in the same manner as able-bodied
people (Fig. 4). We are conducting a series of experiments to determine how moving an avatar robot[OriHime-D] in a low-latency network condition
affects actual tasks. Thanks to the high-speed communication provided by IOWN, the robot can movesmoothly along narrow routes and get to its desired
destination reliably even if that location is not predetermined, which was not possible when using theordinary Internet.
It is not human-like to move along a predetermined
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Feature Articles

Demonstration experiment of remote control of avatar
robot (press release published on Nov. 2)

Avatar robot
OriHime-D

Fig. 4. Case 1 : Avatar robot café “DAWN” Ver.β.

route, in a predetermined form, and in a predeterminedorder. Unfortunately, OriHime-D operating over theordinary Internet cannot act exactly the same as ablebodied people such as flexibly handling unplannedtasks and oral requests on the spot.
If high-speed networks could be expanded, all fivesenses could be transmitted to the customer’s location, and people with disabilities could work as if
they were at that location. As a result, they would
have a wider range of tasks they could handle, andmany things would become feasible for them. I also
believe that the differences between disabled andnon-disabled people would become less. I would bepleased if we could create such an environment.”
I had talked about this avatar robot café with Kentaro Yoshifuji, CEO of OryLab Inc. six or seven years
ago. People like us, who work in communicationindustry, thought that “interactivity” was the basis ofcommunication. For example, when we develop communication services, we assume that they will be able
to communicate in both directions, but OriHime canonly communicate one-way. It uses unidirectional
video to communicate, so only the pilot—a personwith disabilities—can see a customer but the customer cannot see the pilot. Therefore, it does notconvey information in two directions; rather, it conveys its presence in one direction. Such two-way andone-way communication systems will probably exist
naturally in the future. When such systems are controlled remotely, latency often becomes a problem. In
this demonstration experiment with OriHime, wewere able to connect NTT Musashino R&D Center inwestern Tokyo to Nihonbashi in central Tokyo andmove the robot with a delay of less than 20 ms. Sincesuch remote control is normally operated in about a
400-ms delay, we were able to achieve remote control
with 1/20 the normal delay.
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3.2 Cloud-based e-sports events
One of the most effective use cases of the All-Photonics Network is in cloud-based fighting games. In
such games, it is important to stream 8K video with adelay of less than 20 ms. When we compare the environment of a few milliseconds delay and 20–30-ms
delay, we can clearly recognize the timing gap of two
game characters’ actions. In an environment where
the timing of kicks does not match due to the delay, it
is difficult to play. While the delay is still 20 ms in thecase of OriHime mentioned above, we are now working to reduce it to a few milliseconds. We are also
currently researching and developing a system thatcan synchronize actions of game characters by controlling the delay in the order of microseconds.
3.3 Security in the age of quantum computing
Another use case of the All-Photonics Network issecurity. We developed an encryption method by
combining conventional methods (e.g. RSA (Rivest–
Shamir–Adleman) cryptography) with a cipher
method called NTRU (Nth Degree Truncated Polynomial Ring Unit) (Fig. 5) on the basis of the computational difficulty of the lattice problem. Commercialization of this encryption method is currently underway. The information processed with this encryption
method cannot be deciphered even with quantum
computers.
In the All-Photonics Network, the delay time can beevaluated in advance. As the delay time changes
when somebody eavesdrops or accesses withoutauthorization, it is possible to instantly detect whether there was an external access. Even though NTRU
prevents the information from being deciphered
whenever the network is eavesdropped, we aim to
make the network capable of detecting eavesdropping
as well.
4. Advances in photonics-electronicsconverged devices
Current semiconductors generate a large amount ofheat as they are operated by electrons (Fig. 6). To
address this issue, we are researching and developinga photonics-electronics-converged device that will
enable inter-chip optical transmission and plan toannounce it at Expo 2025 in Osaka, Japan. By 2030,
we aim to make a photonics-electronics-converged
device that enables both inter-chip and intra-chip
optical transmission.
In the era of IOWN, various elements will be combined to form a single system. For example, in the late14

Feature Articles<New encryption method>
Basic encryption
Conventional method(RSA encryption etc.)

Prime factor
decomposition

Post-quantum
cryptography
proposed by NTT(NTRU encryption)

Lattice problem

Tolerance forTolerance fortraditional computer quantum computer<New monitoring method>• Delay time is almost constant on the All-Photonics Network due to end-to-end
optical connection• Detect attacks or anomalies by detecting fluctuation of delay time triggered by
wiretapping

Fig. 5. Case 3: Security for quantum computing.

2021

2025

2030

Inter-chip

Electrical

Optical

OpticalIntra-chip

ElectricalElectrical

OpticalFig. 6. Evolution of photonics-electronics-converged devices.

2020s, photonics-electronics-converged chips will beapplied to mobile communication facilities. In addition, a new optical interconnect device (called superwhite box) that transcends the traditional concept of
the server is planned to be introduced.
5. Toward achieving carbon neutrality
In 2013, NTT Group emitted about 1% of Japan’s
greenhouse gas emissions, which was about 4.65 million tons per year (Fig. 7). To reduce greenhouse gas
emissions, we will promote energy conservation anduse renewable energy. However, the amount of greenhouse gas emissions will still increase if we only takethese measures without any other solutions since theamount of electricity usage increases in conjunction
with the increase in information processing. To
achieve carbon neutrality, we need to leverage thepower of IOWN.
We aim to achieve carbon neutrality in the datacenter and mobile sectors by 2030 and throughout the
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entire NTT Group by 2040. We must solve environmental problems through innovation and drive economic growth simultaneously. While these goals arecontradictory, we will tackle them with a paraconsistent approach. We believe that we can contribute to
reducing the environmental impact of the entire society through the introduction and expansion of IOWN.
6. How to transform NTT GroupWe are currently focusing on three pillars to transform NTT Group (Fig. 8). The first pillar aims tostrengthen our domestic and global businesses asdigitalization and digital transformation (DX)spreads around the world. Regarding the second pillar, in both “corona” and “post corona” societies, weneed to introduce a new management style to copewith the transition as we move toward a decentralizedsociety. The third pillar is to increase our corporate
value through ESG (environmental, social, and corporate governance) and other initiatives to maximize
15

Feature Articles(8.6 million tons)
Outcome(Millions of tons)

Reduce10%

Energysavings

Greenhouse gas emissions

Reduce 55%
IOWN

Reductionof energy
consumption

Reduce45%4.65 million tons
4.00 million tons

Reduce 80%
Greenhouse gas
emissions

RenewableenergyReduce 45%
Introductionof renewableenergy, etc.

0.95 million tons
Offsets

2022
2013

2020
Introduction of internalcarbon pricing system

2030

2040

Mobile, datacenters
to be carbon neutral

NTT Group to becarbon neutral(FY)

Social/economic directionality

NTT Group’s directionality

Advancement ofdigitalization/DX

Enhance domestic andglobal businessSociety during COVID-19
and post-COVID-19

A new management stylesuitable for a decentralized
network society

Realization of awell-being society

Enhancement of corporate
value through ESG initiatives

Contribution to the achievementof a sustainable society

Fig. 7. Activities for achieving carbon neutrality.

Fig. 8. Directionality of NTT Group’s transformation.

the well-being of our society. Through the initiativesof these three pillars, we aim to contribute to creatinga sustainable society.

to the future, we would like to further promote a“work-in-life” (health management) approach(Fig. 9).

7. Transformation to a new management style

8. Sustainable societyWith regard to the reform of our management style,we have continued and strengthened remote working
during the COVID-19 pandemic. As a result, employee satisfaction, especially among those raising children, has improved. This fact shows that remote
working can mitigate some of the issues brought bychildcare and both parents working. Looking ahead

Let us think about what kind of sustainable society
we aim for. First, it is a society that cannot be understood by dualism. Next, as the word “diversity”
implies, it is a society that simultaneously embraces
and puts into practice various viewpoints and ideas.
To achieve this sustainable society, the concept of“Self as We” becomes the basic philosophy (Fig. 10).

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Transformation to a new style premised on remote work
Transformationof business/DX

Re-examination ofsystems/general
improvements

Promotion of
remote work

Promotion of “work-in-life” (health management)
Open, global, and innovative business operations

Support of customers’ DX
Improvement of resiliency

Promotion of regional revitalization
Contribution to a decentralized society etc.

Fig. 9. Transformation to a new management style.

Simultaneous existence of
conflicting things that are
not defined as dualism

Fact interpretation differs
Different realities exist
depending on viewpoints
Paraconsistent“Sustainable Society”“Self as We” philosophy
to achieve that goal

Fig. 10. Sustainable society.

Our society has generally been operating under theconcept of “Self as I”—which is about valuing theindividual. According to biologist Dr. Shinichi
Fukuoka, no organism can transcend its species.
However, humans have overcome the idea that only
they and their offspring are important. In other words,
humans have developed as individuals who are notlimited to genetics.
For example, only humans can have the concept ofinclusion of members of the LGBTQ (lesbian, gay,bisexual, transgender, queer) community. If we lookfurther into the next era, our alter egos will extend to
cyberspace. In cyberspace, you will also be able tohave your own family, friends, and community. This
world is also based on “Self as We,” rather than “Self
as I.” I believe we should adopt such a philosophy.
The concept of “Self as We” is that;i)	nature is an altruistic force and we are a part ofit,
NTT Technical Review

Vol. 20 No. 2 Feb. 2022ii)	culture and society are secured by connecting
us through ethics, andiii)	one’s happiness and other peoples’ happinesscoexist (altruistic coexistence).
Accepting the concept of “Self as We,” we set thefollowing three themes to achieve a sustainable society;1) ensure the coexistence of nature and humanity,2)	improve prosperity for all people and cultures,and3) maximize well-being for all (Fig. 11).
We established NTT Group Global Sustainability
Charter on the basis of the above-mentioned “Self as
We” concept and three themes. Along with this charter, we specified our Environment and Energy Vision,
New Management Style, and Human Rights Policy,
which were shared within entire NTT Group globally
[1].

17

Feature Articles“Self as We” concept

Three themes

Nature is an altruistic force, and“We” is a part of that

Ensuring the coexistenceof nature and humanity

Culture and society are secured
by connecting “We”
with the thread of ethics

Improving prosperity for
all people and cultures

Altruistic co-existence(Co-existence of one’s
happiness and others’ happiness)

Maximizing well-being
for allFig. 11. Three themes for a sustainable society.

9. Concluding remarks
I have talked a lot today, and my book, “Paraconsistent World,” which is about to be published, covers
more details through discussion with various experts.
I hope you will find an opportunity to read it.

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Reference[1]

Press release issued by NTT, “Establishment of NTT Group Global
Sustainability Charter - Towards a Sustainable Society -,” Nov. 10,2021. https://group.ntt/en/newsrelease/2021/11/10/211110d.html

18Feature Articles: Keynote Speeches at NTT R&D
Forum—Road to IOWN 2021

Road to IOWN 2021
Katsuhiko Kawazoe
Executive Vice President, Head of
Research and Development Planning
Department, NTT
Abstract

This article presents a lecture given by Dr. Katsuhiko Kawazoe, NTT
Executive Vice President, Head of Research and Development Planning
Department, at NTT R&D Forum 2021—Road to IOWN 2021 held from
November 16th to 19th, 2021.
Keywords: IOWN, connection of Umwelten, concatenated loop topology,
photonic disaggregated computing, Cradio®, 4D digital platformTM, infinite clustering, NTT Green Innovation toward2040

1. Introduction
We announced the concept of the Innovative Optical and Wireless Network (IOWN) in May 2019. At
NTT R&D Forum in 2019 and 2020, I spoke about its
goals, objectives, and base technologies. This is thethird year of the IOWN initiative, so I would like tofocus on its progress and expansion. Since some ofyou may be hearing about IOWN for the first time, letme start with the concept.
2. Negative aspects of human development
The concept of IOWN stems from the current situation of humanity and technology. Humanity has
made various technological innovations that havebrought about a more affluent world. However, thenovel coronavirus (COVID-19) has made all of us
realize that we are now faced with unprecedented
challenges and that our current technology is not sufficient to solve them. We need to improve ourapproach to innovation drastically. However, the current approach to technological innovation has hadserious negative effects, i.e., the depletion of resources, biodiversity loss, environmental destruction, and
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global warming (Fig. 1). I feel that if this trend continues, the Earth and all living beings on it will beoverburdened, and both humanity and all other living
beings may perish. It is believed that the environmental destruction of Easter Island, famous for its Moaistatues, was caused by deforestation stemming froma population explosion. This caused the soil to drain
into the sea, depleting resources and causing conflicts
over resources. Our current technological infrastructure is surrounded by these contradictions and paraconsistencies; economic development and environmental protection, industrial production and resource
conservation, and information and communication
technology (ICT) development and power consumption.
3. What kind of innovation do we need?
What kind of innovation do we need to create asustainable society? The answer is innovation that
achieves a significant performance improvement of
the technological infrastructure without placing aburden on the Earth. Our conclusion is that we should
not focus only on humans, but also recognize andimplement innovations for all living beings and the19

Feature Articles

Power consumption

Fig. 1. Negative aspects of human development.

Photonic transmission
Electric transmission

Transmission distanceFig. 2. T he “connection of Umwelten” to use the wisdomand value of all Umwelten.

entire Earth as a whole system. We should do our best
to widely adopt the technologies that will have theleast impact on Earth.
4. How to do it?
What we have been proposing as an effective strategy for recognizing and using the total system is the“connection of Umwelten” (Fig. 2). The world as wehumans perceive it is not all there is. Various
Umwelten exist around us, for example, the Umweltenof insects, reptiles, and fish. Perhaps even non-living
things, such as viruses, have their own Umwelten. To
understand the world made up of various Umwelten,
we need to use the wisdom and value of each of them.
This is the “connection of Umwelten.” To do this, weneed to overcome two barriers.
5. Barriers
The first barrier is the understanding all Umwelten.
In the past, humankind has learned from nature toenhance wisdom and promote innovation. However,this is very limited. There are still many Umweltenthat have yet to be approached. Bioengineering and
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Fig. 3. Advantage of photonic transmission.

biotechnology are truly academic disciplines that
discover the characteristics of various living beings
and apply them to our society. It will be necessary tolearn not only from the Umwelten of living beings but
also from those of non-living things such as viruses.
As you all know, viruses are not living organisms, butthey have a great impact on humanity. If we canunderstand the mutation process of viruses, we canbring a ray of hope to many people.
The second barrier is the technological infrastructure for connecting Umwelten. We need to go beyond
humanity’s Umwelt and choose those that are usefulfor improving well-being and create a connection that
does not place a burden on the Earth. This requires
information processing more complex and extensive
than ever before. We believe that the expansion of
optical technology can help solve this problem.
Optical technology has been mainly applied to thetransmission of information via optical fiber. This hascreated a significant increase in transmission speed
and capacity. Compared with electricity, light has
great potential in terms of energy consumption(Fig. 3). Therefore, we need to overcome technology
barriers and extend optical technology from transmission to information processing.
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Cognitive
Foundation®

Cloud

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End-to-end coordination of ICT resources

Network services
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Agile allocation of ICT resources
Optimization of structure

API

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All-Photonics Network

PublicPrivateProcessor using
photonics-electronics
convergence
technologies
API: application programming interface
Ctrl: controller

Fig. 4. IOWN concept.

6. Concept of IOWN
NTT has been conducting extensive research anddevelopment of optical technology since the 1960s.
This is extending from information transmission to
information processing. In information transmission,
optical technology has progressed mainly through theevolution of optical fibers and technological innovations in transmission processing technology, such as
digital signal processors. In information processing,
we have been unable to create a breakthrough technology that surpasses electronics technology. In April
2019, however, NTT succeeded in inventing theworld’s first optical transistor [1]. This is the origin of
the concept of IOWN (Fig. 4). Since then, we havesucceeded in inventing a variety of optical devices
and found a means of extending optical technology to
information processing.
In artificial intelligence (AI), for example, research
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and development is currently underway worldwide to
improve its capabilities. We believe that we can makeprogress with a completely different approach. Current AI research is believed to be a technology toachieve the goals set by humanity. However, as I
mentioned, we need to find yet unknown Umwelten
and understand them. The increase or decrease in thenumber of people infected with COVID-19 may be
one such subject. A future AI needs to know theunknown. As I have said repeatedly, this AI must notburden planet Earth but should instead lead to thewell-being of the whole planet. To create such aworld, the NTT Group is focused on the concept of“Self as We.”
Self as We refers to the concept of “I” as “we.” It is
the idea that my existence is supported by connections with all types of entities, including people,
things, and technologies. Therefore, we need tomaximize the well-being of “us” through altruistic
21

Feature Articles

Cognitive
Foundation®

4D digitalplatformTM

Zeroenvironmental
impactEdge
Digital Twin Computing

Cloud

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Well-being

Security

DTC grandchallenge

Digital Twin Computing

rdination of ICT
IC resources
End-to-end coordination
Data-centric computing infrastructures

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Providerd C Ctrl
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World

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Device Computing
Network

Extreme NaaS

All-Photonics
All Photonics
A
onics
o
cs Network
Netwo
Netw
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All-Photonics Network (APN)

PublicProcessor using
photonics-electronics
convergence
technologies

Photonicselectronics
convergence
technology

PrivateDisaggregated computing

IOWN
UI/UX

Fig. 5. Research areas under the IOWN initiative.

coexistence. Since nature is altruistic and we are apart of it, we need to live in harmony with nature.
Through the concept of IOWN, we will promote initiatives to achieve a sustainable society by simultaneously achieving growth and solving social issues.
7. Latest progress in the IOWN initiative
I will now discuss the latest progress in the IOWN
initiative. This started with the invention of the optical transistor by one of NTT’s research laboratories
and has now spread to the entire NTT Group andbeyond—to a global level. I will explain the progressin the technologies that have already been announced,
as well as 15 new technologies that will be announced
for the first time (Fig. 5).
7.1 All-Photonics Network (optical access network design based on concatenated loop
topology)
The first technology is our new access network, theNTT Technical Review

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optical access network design based on concatenatedloop topology, which is a component of the All-Photonics Network (APN) introduced in 2021 [2]. To
create a smart society in areas such as telemedicine
and automated driving, the APN will provide a reliable and flexible infrastructure-of-infrastructure.
The new IOWN optical access network will evolve
significantly in three areas, i.e., reliability, tolerance
for fluctuation of service demand (flexibility), andoptical-path selectivity (scalability).
To achieve these goals, we established the opticalaccess network design based on concatenated loop
topology (Fig. 6). Circular optical fiber primary loops
spread from the NTT building (central office), andsecondary loops are connected to them via fiber crossconnections. Mobile base stations are connected tosecondary loops. This configuration improves reliability because there are multiple routes between the
NTT building and mobile base station. The number ofcore lines can also be flexibly allocated according to
demand, and unexpected increases in demand can be
22

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Scalable

Fiber cross connection
Secondaryloop
DistributionsectionPrimaryloop

Scalable pathselectivity

Overlaid

ReliableHighly reliable
path duplexing

Newly designed
access network

Flexible

Flexible fiber
reassigning

Conventional
access network
Existing civilengineering
infrastructure

Fig. 6. Optical access network design based on concatenated loop topology.

quickly accommodated. Neighboring mobile basestations can also be connected to each other without
having to go through the NTT building.
We also clarified the appropriate value of designindicators for this new network through theoretical
calculations based on reliability engineering andprobability theory. We developed a remote opticalpath-switching node that does not require commercial power supply and confirmed the principle of thevariable optical branching ratio.
We will continue to promote research and development of this technology for practical use.
7.2 Distance Zero
The second technology is Distance Zero, a technology to overcome the physical distance brought about
by the APN. We succeeded in reducing networklatency fluctuation to the microsecond level, which is
close to the physical limit between locations, forcommunication of more than 100 Gbit/s per wavelength [3]. By installing an IOWN adapter at theuser’s location, we can provide a 100-Gbit/s communication path to a user’s device with no latency fluctuation. IOWN adapters enable overheadless 1000km long-distance transmission by transporting
uncompressed or slightly-compressed HDMI (highdefinition multimedia interface)/DisplayPort andUSB (universal serial bus) signals through over-100Gbit/s optical paths of the APN. Even with the APN,
which can provide overwhelmingly low latency compared with conventional Internet Protocol (IP) networks, there are physical limitations such as the
speed of light and occurrence of network latency
depending on the communication distance. We develNTT Technical Review

Vol. 20 No. 2 Feb. 2022

oped a technology that enables the APN to automatically compensate for the delay difference.
Distance Zero will enable e-sports events to be heldin various cities under fair conditions, i.e., the same
delay difference among various cities. We will continue to improve this technology by taking advantageof the APN’s high-capacity, low-latency, and zerofluctuation performance. Our aim is to create a future
where users can easily participate in e-sports without
a game console.
7.3 B
 idirectional wireless transmission using a
Van Atta array in Beyond 5G
I’ll now talk about new innovations in IOWN’s W,
i.e., wireless, which is connected to the APN. Manyof the technologies related to IOWN are based on
simple principles. The wireless technology I am
about to talk about is also simple but greatly effective.
There is no need for complex processing. We focusedon the principle of the Van Atta array antenna, which
is based on retroreflection, a method of engineering
radio waves so that they are reflected directly back tothe source no matter from what direction they hit. By
adopting the Van Atta array, it is possible to constructantennas with retroreflective properties in the mostcompact and simple way possible. For drastic performance improvement of wireless systems, we, with
the Tokyo Institute of Technology, successfully demonstrated the world’s first bidirectional wirelesstransmission using a Van Atta array [4].
In wireless communication using high-frequency
bands, such as millimeter or terahertz waves, which
will be used in beyond fifth-generation mobile communication systems (Beyond 5G), it is necessary to23

Feature Articles

form a sharp directivity by controlling the phase ofeach element of the arrayed multi-element antennas
and always direct the antenna towards the communication partner because the propagation loss of thesignal is large. This requires complex signal processing and directivity control mechanisms to track themoving communication partner.
The Van Atta reflector array antenna we demonstrated can be applied to telecommunication, reflect
radio waves in the direction of incidence withoutcomplicated signal processing and control, and further reduce power consumption by eliminating thecomplicated functions of beam selection and antenna
directivity control that conventional wireless basestations and terminals have.
We will promote the practical application of thistechnology in a wide range of wireless systems.
7.4 W ired-and-Wireless Convergence Network
technology
In preparation for Beyond 5G, the NTT Group has
begun considering the Wired-and-Wireless Convergence Network. In the next generation after 5G, features of mobile and fixed networks are expected to bemerged to create unprecedented services, and you
will not notice the difference.
The Wired-and-Wireless Convergence Network
consists of function dedicated networks (FDNs) for
each virtual endpoint function. By placing virtual
endpoints as communication endpoints on the computing infrastructure, and connecting them with an
FDN for each function, seamless communication canbe provided at the end of the network without users
noticing the access or terminal. With this networkfusion technology, the fusion of cyberspace and real
space, as well as computers and networks, will befurther developed. Not only humans, but also a wide
variety of objects will be able to communicate without being restricted by communication environment,
location, or terminal type, enabling the creation of a
new generation of services that require high stability
and reliability.
7.5 D isaggregated computing: memory-centricarchitecture
I will now talk about the progress in disaggregatedcomputing in which distributed computing devices
are connected by light. The computational efficiencyof accelerators, such as graphics processing units(GPUs) and field-programmable gate arrays (FPGAs),
has dramatically improved compared with that ofcentral processing units (CPUs), which are generalNTT Technical Review

Vol. 20 No. 2 Feb. 2022

purpose processors. However, when sharing andpassing data between accelerators, the CPU isinvolved, which reduces efficiency in terms of processing speed and power consumption. To solve thisproblem, NTT has devised a computer architecture inwhich the accelerators are equipped with opticalcommunication functions, allowing them to communicate directly with the memory using light (Fig. 7(a)).
This dramatically improves the processing performance of the computer and reduces the CPU load andpower consumption. The architecture consists of ascalable pool of accelerators that can be combined ala carte in accordance with the application, enablinga highly scalable and efficient computing infrastructure (Fig. 7(b)). We call this new computing architecture the memory-centric architecture.
We developed a prototype of the memory-centricarchitecture using a conventional device and verified
its effectiveness using video-based AI inference as atest case. We confirmed that it reduces power consumption by about half compared with the conventional architecture. We estimate that power consumption will eventually be reduced to about 1/20 that of
the conventional architecture through the evolution ofphotonics-electronics convergence technology andfurther development of this architecture using thistechnology.
7.6 Security-transparency-assurance technology
The next technology I will discuss is the securitytransparency-assurance technology, which uses
IOWN’s photonics-electronics convergence technology to solve the security problems of decentralized
computer devices. Decentralization increases the riskof malicious software and hardware. Therefore, visibility and inspection of the hardware and software isnecessary to improve security transparency. NTT isdeveloping this technology in collaboration with
NEC Corporation [5].
I will now introduce the elemental technologies ofthe security-transparency-assurance technology, i.e.,a technology for analyzing the software configurationof telecommunication equipment and a backdoor
inspection technology for detecting illegal functions
in software. To externally inspect communicationequipment, we match device-specification data with
device-operation data to detect out-of-specification
behavior. We achieved the detection of out-of-specification code that does not normally run by directly
analyzing the binary code inside a device. This technology will allow for versatile, high-performance andsecure white boxes consisting of software and24

CPU
MemoryCPU
MemoryAccelerator

Accelerator

Accelerator

Accelerator

Accelerator

Accelerator

Accelerator

Accelerator

Accelerator

Accelerator

Accelerator

Shared Memory

CPU
MemoryShared Memory

CPU
MemoryShared Memory

CPU load: Low

Shared Memory

Feature Articles

Accelerator

Accelerator

Accelerator

Accelerator

Accelerator

Storage

Storage

Storage

Storage

NIC

NIC

NIC

NIC

(a) To reduce CPU load and power consumption by directly
communicating with a memory using light(b) A scalable pool of accelerators that can be combineda la carte in accordance with the application

NIC: network interface cards

Fig. 7. Progress in disaggregated computing (memory-centric architecture).

hardware devices supplied by multiple vendors to
become the next generation of communication devices. NTT calls such super high-performance generalpurpose devices super white boxes, which will beapplied to various IOWN communication-infrastructure devices.
7.7 Post-quantum cryptography
I’ll talk about cryptography for the IOWN era, theera of quantum computers. Quantum computers are
expected to be applied to various fields, but if they are
put to practical use, there is a possibility that existing
cryptography, which ensures a secure communication
infrastructure, will be broken. Research on the next
generation cryptography post-quantum cryptography(PQC), which cannot be broken even by quantum
computers, is being conducted worldwide. The
NTRU (Nth Degree Truncated Polynomial Ring
Unit) cryptography developed by NTT includes
security-enhancement technology that can be applied
to PQC. It is one of the last remaining candidates in
the PQC standardization activity at the U.S. National
Institute of Standards and Technology and is highly
evaluated by cryptographers around the world [6]. We
would like to combine this cryptography to constructa robust communication system.
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Vol. 20 No. 2 Feb. 2022

7.8 C
 radio® multi-radio proactive control technologies
I will now talk about the progress in the Cognitive
Foundation® that enables rapid deployment and configuration optimization of ICT resources. Beyond 5G
requires extreme coverage that can connect and stayconnected across land, air, underwater, space,indoors, as well as outdoors. A promising method forachieving extreme coverage is the moving base station. Drones equipped with base-station functions
could be flown to locations where there is a sudden
increase in users. To meet this new need, NTT developed multi-radio proactive control technologies
called Cradio®. This group of technologies estimatesconnection strength, derives station locational
designs, and organizes wireless resources.
The logistics industry has been using automatedrobots at unmanned warehouses. For automatedrobots to operate accurately, it is necessary to createa network that remains connected and uninterrupted,
even when the location of the robots or the environment in the warehouse changes. By applying Cradio®, we were able to combine information from thewireless environment with business information suchas the increase in, decrease in, or arrangement ofcargo, to enable the wireless network change
25

Feature Articles

Fig. 8. Application example of Cradio®. The position of the moving base station in advance based on theamount of cargo.

autonomously in accordance with changes in theenvironment and stay connected (Fig. 8). By dynamically changing the position of the moving base station in advance on the basis of the amount of cargo,
we can maintain an optimal wireless environment.
We aim to enable self-evolving lifecycle management of ICT resources in a multi-domain, multi-layer,
and multi-service vendor environment with automatic design and autonomous operation of all types of
ICT resources.
7.9 L
 arge-scale three-dimensional spatial information processing technology
I would like to talk about the progress in the 4D
digital platformTM. This platform was designed tosolve social issues and create new value by integrating various sensing data on a three-dimensional (3D)
map database with high accuracy and rich semantic
information, processing the data with high accuracy
reflecting the time axis with for example real-time
analysis, and providing the data to various industrial
fields.
I will specifically talk about large-scale 3D-spatialinformation processing technology, which is one of
the technologies that make the 4D digital platformTM
possible. Point-cloud data representing a space areusually acquired piecemeal by using, for example,
measuring vehicles, but there are various challenges
in integrating and using these data for an entire city.
Figure 9 shows point-cloud data for one corner of
NTT Technical Review

Vol. 20 No. 2 Feb. 2022

a city. The point clouds of different colors were collected on different dates, and only some of the data
are overlapping. This makes it difficult to extract anduse only some of the data due to the large quantity. In
contrast, by applying new technology that compresses point-cloud data by dividing them into multiple
blocks, it becomes possible to handle such data. It isalso possible to handle blocks in a hierarchical manner, which makes it possible to efficiently handle dataof large cities that are difficult to handle with conventional point-cloud-data processing.
There is also an ingenious means of comparing
point clouds that have changed over time. The yellow
area in Fig. 9 represents the point-cloud data collected in the past, and the pink area represents the pointcloud data currently being collected. Even if the two
are displayed at the same time, it is difficult to notice
the amount of change. Therefore, by visualizing theareas of change in small blocks instead of points, we
can efficiently find only the areas of the city that havechanged.
NTT is also developing a technology that uses deepneural networks to estimate structures from pointcloud data and automatically recognize 3D objects
such as subway entrances and exits, manholes, andsidewalk edges.
Using these technologies as a foundation, we willfurther integrate environmental sensing data, GPS(Global Positioning System) positioning data, andexisting map information to create an advanced
26

Feature Articles

The point-cloud data provided by Asia Air Survey Co., Ltd.

Fig. 9. Application example of 4D-point-cloud coding technology.

geospatial database. This database can be used as adigital twin of urban assets for the coordinated conservation of social infrastructure.
7.10 Infinite clustering technology
In the introduction, I talked about the world viewthat IOWN aims to achieve, and I would like to talkabout an important technology that will help us
understand the unknown world. Considering infinite
possibilities and unknown events, we have devised
the world’s first infinite clustering technology thatcreates an infinite search space by flexibly grasping
the concept of the analysis target [7]. This is a breakthrough in clustering technology, which reorders data
to create clusters with common features. Clustering iseasy to understand if you think of it as a technology
for sorting and aligning data, such as a Rubik’s Cube
(Fig. 10(a), left). By clustering, we can discover hidden patterns in seemingly disordered data.
With normal clustering techniques, it is necessary
to know in advance what kind of clusters exist. In thecase of a Rubik’s Cube, six different colored clusters
are given in advance. Imagine that you never heard of
Rubik’s Cube. You can imagine that it would be very
difficult to know what to aim for when you are playing with the cube (Fig. 10(a), right). Our infinite
clustering technology can generate an infinite number of combinations with an unknown number ofchunks and features and create optimal clusters(Fig. 10(b)).
Since this technology allows us to explore infinite
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Vol. 20 No. 2 Feb. 2022

possibilities, we can add more factors than before andexplore the relationships between the factors, which
can be organized in clusters. For example, when aperson visits a hospital because he or she is feelingunwell, but no lesion or disease is found that would
lead to physical discomfort, in other words, anunidentified complaint, various factors can be added
to find the cause. We search for infinite possibilities
by adding various factors such as “at what time, atwhat temperature, in what climate, and how was thepatient feeling.” We may be able to find a cause wenever thought of. We have already started this type ofstudy. By having a variety of perspectives, this technology can get us out of the world of looking at thetrees and not seeing the forest. We have also been able
to guarantee that the technology will work without
failure even when the input data becomes infinitely
large.
This infinite search technology requires an enormous amount of processing time, but we believe thisproblem will be solved with the advancement in
IOWN computers. We also believe that the coherent
Ising machine LASOLV, which is being developed byNTT, can be used to speed up the processing.
LASOLV has evolved since it was first announced
and is now able to achieve 100,000 spins. It can findsolutions to a 100,000-node combinatorial optimization problem 1000 times faster than simulated
annealing used by CPUs and still with the same accuracy.
This technology has the potential to create AI
27

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1110

Perplexity

9
8
7
6
5
4

0

10

20

30

40

Iterations(a) Infinite clustering technology will help us understandthe unknown world(b) Example of complicated clustering with infinite
clustering technology

Fig. 10. Infinite clustering technology.

unlike anything seen before, enabling us to pursue
well-being from various perspectives. We hope to
improve this technology to promote well-being witha global perspective.

value that we never thought possible.
To promote the research and development of new
UIs for the IOWN era, we have started a collaboration
with ACCESS Inc.

7.11 Terminal user interfaces in the IOWN era
I would like to talk about how terminal user interfaces (UIs) will change in the IOWN era. Terminal
UIs will connect to ultra-high-speed, low-powerconsumption, low-latency network infrastructuresthat current IP networks cannot provide. They will be
freed from various restrictions and what is now considered common knowledge. For example, it is common knowledge that content has to accept the intentions of the producer uniformly, and information suchas video and audio is always compressed to reduce
the load on networks and terminals. However, in the
IOWN era, this sometimes changes depending on the
purpose.
The point with the new UIs is that the information
received will change depending on the values andenvironment of the recipients of the information, andthat new discoveries will be made by the recipients.
Even if the information is the same, you can understand it from the viewpoint of others who have different values from yours and become inspired or feel
empathy. For example, you can discover problems bylooking at a city from the perspective of a disabled
person, or try to see and feel a creative work from theperspective of the opposite sex. Exposure to a varietyof Umwelten can draw inspiration and create new

7.12 N TT Group’s new environmental and energy vision
I have thus far talked about the progress in certain
IOWN technologies. I will now talk about how
IOWN can reduce environmental impact. The NTT
Group’s new environmental and energy vision wasannounced at the end of September 2021 [8] (Fig. 11).
If the current situation continues, the amount of carbon dioxide (CO2) emitted by the NTT Group per
year will be approximately 8.6 million tons in 2040.
By introducing energy conservation and renewableenergy, we will be able to reduce CO2 emissions by
55%, and by introducing IOWN, we will be able toreduce electricity consumption by 45% and achievecarbon neutrality by 2040. We assume that IOWN
will be used worldwide by 2030. NTT will complete
the development of IOWN devices by 2024, IOWN
systems by 2025, and commercial launch in 2026.

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7.13 IOWN space-computing concept
IOWN makes innovative new energy measures possible. I will now talk about the progress in the IOWN
space-computing concept announced in 2020 to build
a new space ICT infrastructure independent fromplanet Earth.
In May 2021, we began a partnership with SKY
28

Feature Articles(8.6 million tons)
Outcome(Millions of tons)

Reduce10%

Energysavings

Greenhouse gas emissions

Reduce 55%
IOWN

Reductionof energy
consumption

4.65 million tons

Reduce45%
by IOWN

4.00 million tons

Reduce 80%
Greenhouse gas
emissions

RenewableenergyReduce 45%
Introductionof renewableenergy, etc.

0.95 million tons
Offsets

2022
2013

2020
Introduction of internalcarbon pricing system

2030

2040

Mobile, datacenters
to be carbon neutral

NTT Group to becarbon neutral(FY)

Fig. 11. NTT Group’s new environmental and energy vision: NTT Green Innovation toward 2040.

Perfect JSAT to materialize this concept [9]. We areintegrating the IOWN technology with SKY Perfect
JSAT’s space assets and business for commercialization and currently working together to solve a variety
of issues. For example, with a single observation
satellite, the timing of data transmission to groundstations is limited, and in some cases delays of several days occur. Therefore, high altitude platform
stations flying in the stratosphere and satellites in low
to geostationary orbits are integrated via optical radio
communication, and the data acquired by the observation satellites are immediately transmitted to theintegrated satellite system for distributed processing.
Only the required processing information is transmitted from satellites that are close to the ground station,
which greatly reduces delay time. This is the Space
Integrated Computing Network presented by bothcompanies. By creating this infrastructure, we willcontribute to the dramatic improvement in real-time
space-data utilization and user convenience and work
to solve global-scale social issues.
We are developing this infrastructure with the aimof starting operations in 2025. As a part of this development, we are planning to conduct a demonstration
experiment on one of the Japan Aerospace Exploration Agency’s satellites in orbit in 2022. The Space
Integrated Computing Network, which connects thevastness of space using light, will be the ultimate ecoNTT Technical Review

Vol. 20 No. 2 Feb. 2022

friendly infrastructure and break away from terrestrial energy.
7.14 Space solar-power generation
The next environmental initiative I would like totalk about is space solar-power generation. This is anext-generation energy source that generates solar
power in space and transmits that energy to Earth.
NTT laboratories are conducting research and development on three technologies.
The first is a technology that collects sunlight ingeostationary orbit 36,000 km above the ground andirradiates the collected light directly onto a special
crystal we developed installed on a satellite to excite
a laser with high efficiency.
The second is a technology to transmit lasers fromspace to the ground. When lasers pass through theatmosphere, atmospheric turbulence causes misalignment of the path and performance degradation.
Therefore, we are researching technology to avoid
such atmospheric effects and deliver lasers accurately
over a long distance. When energy sent from the universe is visible light, because of the attenuation
caused by atmospheric absorption and scattering andthe fact that the human eye can detect it, an infraredlaser is a good candidate.
The third technology is a photoelectric conversion
system that can withstand the high intensity of29

Feature Articles

Sponsor

84

GeneralAcademic research

32

3Jan. 2020

Oct. 2020

Dec. 2021
As of Dec. 31, 2021

Fig. 12. Changes in the number of IOWN Global Forum members.

infrared lasers coming from space and generate electricity with high efficiency. We are also looking into
technologies to convert electric power into storable
forms, such as hydrogen and ammonium, using thermochemical reactions and catalysts. By linking thisspace solar-power generation system with the Space
Integrated Computing Network I mentioned earlier,
we aim to use energy obtained in this manner for local
production and consumption.
7.15 Lightning-strike control technology
I would like to talk about the progress in the lightning-strike control technology that we announced in2020. It prevents lightning strikes on importantfacilities and creates electricity from the lightning.
From the observation of thunderclouds from theSpace Integrated Computing Network, drones can bebrought close to clouds that are likely to cause lightning strikes to form a route to guide lightning andprevent it from striking the city. The current fromlightning strikes can be sent to lightning-charging
vehicles as electricity. We are developing the world’s
first drone that can withstand lightning. The drone isequipped with a metal shield called a Faraday Cage toprotect it from lightning strikes. We tested the lightning resistance of the drone by striking it with artificial lightning. It flew without malfunction or failure
even after being struck by lightning. We also verified
that lightning can be induced through wires.

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8. The IOWN Global Forum and new
NTT organizations
I will now talk about the IOWN Global Forum,
which is promoting IOWN and new NTT organizations.
8.1 IOWN Global ForumThe IOWN Global Forum, founded in January 2020
by NTT, Intel, and Sony, has grown to 80 members inless than two years, including the world’s leading ICT
companies that support IOWN’s vision and innovation [10] (Fig. 12).
In addition to ICT companies such as Microsoft,
Dell, Ericsson, and Nvidia, and companies such as
Ajinomoto, Shin-Etsu Chemical, Yazaki Corporation,
and AGC that possess device technologies, companies and organizations such as Mitsubishi Chemical,
JGC, and NIED have joined as users of the IOWN
technology. The forum aims to develop the technology and discuss use cases. Due to the pandemic, wehave been conducting our activities online but are
actively promoting global activities, including therelease of three use-case documents and technicaldocuments, starting with the white paper released in
April 2020.
8.2 The IOWN Integrated Innovation Center
The IOWN Integrated Innovation Center was established on July 1, 2021 to strengthen research anddevelopment capabilities to develop IOWN and 6G.
We will accelerate research and development toward30Feature Articles

the implementation of IOWN by promoting flexible
and integrated research and development that transcends the boundaries of technological fields andcollaborating with many companies in Japan andoverseas.
8.3 The NTT R&D Authority TeamI am pleased to announce the formation of the NTT
R&D Authority Team. The purpose of this team is tolead our research and development on IOWN andbeyond with renowned authorities in various fields.
The team plays a leading role in each research area
through implementation, guidance, and advice on
research themes [11].
8.4 Basic mathematics research
To further strengthen research and development
over the long-term, we established an organization topromote basic mathematics research [12]. In addition
to working on the development of a basic theoreticalsystem for modern mathematics, this organization
will take an unprecedented approach to research anddevelopment using modern mathematical methods toaddress various research issues to promote IOWN,
such as the identification of unknown diseases anddiscovery of new drugs. We will attempt to establish
a theory of super quantum computation, consciousness for the post-quantum era, and construct a braintype computational model. It is overseen by Research
Professor and Fundamental Mathematics Research
Principal Masato Wakayama, a leading expert inbasic mathematics in Japan.
9. Conclusion
I talked about the progress in IOWN, an innovativetechnology that does not burden the Earth, by seeing
the world as it is instead of a human-centered digitalization. IOWN contributes to “The Great Reset,” thetheme of the 2021 Davos Forum, for reviewing all
aspects of society and the economy.
The NTT Group will make every effort to develop
IOWN by launching IOWN devices in 2024, IOWN
systems in 2025, and commercial deployment in

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2026.
Through IOWN, we would like to contribute tosociety by collaborating with people in various industrial fields beyond the NTT Group and explore new
possibilities together. We will continue to take on thechallenge of breakthrough innovation to ensure thecontinued happiness of humans, animals, and theEarth. Thank you very much for your kind attention
today.
References[1]

Press release issued by NTT Basic Research Laboratories, “Realization of an Ultra-energy-saving Electro-optic Modulator and Highlyefficient Optical Transistor,” Apr. 16, 2019.
http://www.brl.ntt.co.jp/E/2019/04/latest_topics_201904161802.
html[2] Press release issued by NTT, “Optical Access Network Design Theory
Based on Concatenated Loop Topology Was Established for Supporting IOWN,” June 18, 2021.
https://group.ntt/en/newsrelease/2021/06/18/210618a.html[3] Press release issued by NTT, “Unprecedented Optical Network Technologies to Support Esports Achieving Breathtaking Gaming UX in
Remote Esports Events,” Nov. 2, 2021.
https://group.ntt/en/newsrelease/2021/11/02/211102b.html[4] Press release issued by NTT, “For the First Time in the World, aBeamforming Antenna that Reflects Radio Communication Waves
Back to Source without Control Is Demonstrated,” Oct. 18, 2021.
https://group.ntt/en/newsrelease/2021/10/18/211018a.html[5] Press release issued by NTT, “NTT and NEC Have Developed Supply
Chain Security Risk Reduction Technology for ICT Infrastructure,”
Oct. 27, 2021.
https://group.ntt/en/newsrelease/2021/10/27/211027b.html[6] Press release issued by NTT on Nov. 5, 2021 (in Japanese).
https://group.ntt/jp/newsrelease/2021/11/05/211105b.html[7] NTT Communication Science Laboratories, “Permuton-induced Chinese Restaurant Process,” on GitHub.
https://github.com/nttcslab/permuton-induced-crp[8] Press release issued by NTT, “NTT Group’s New Environment andEnergy Vision, ‘NTT Green Innovation toward 2040’,” Sept. 28, 2021.
https://group.ntt/en/newsrelease/2021/09/28/210928a.html[9] Press release issued by NTT, “NTT and SKY Perfect JSAT Conclude
Collaboration Agreement on New Space Enterprise to Aid Realizationof a Sustainable Society,” May 20, 2021.
https://group.ntt/en/newsrelease/2021/05/20/210520a.html[10] IOWN Global Forum, Members,
https://iowngf.org/members/[11] NTT R&D Authority Team (in Japanese),https://www.rd.ntt/organization/authority/[12] Press release issued by NTT, “NTT Has Established the Institute for
Fundamental Mathematics Advancing the Pace of Exploration into
the Unexplored Principles of Quantum Computing,” Oct. 1, 2021.
https://group.ntt/en/newsrelease/2021/10/01/211001a.html

31

Feature Articles: 2021 International Sporting Event and
NTT R&D—Technologies for Supporting Athletes

Women’s Softball × Sports Brain
Science
Masumi Yamaguchi, Daiki Nasu, Dan Mikami,
Toshitaka Kimura, Takehiro Fukuda, and Makio Kashino
Abstract

In the world of sports, the key to success is often the ability to make snap decisions and act instinctively faster than making conscious decisions. The Kashino Diverse Brain Research Laboratory at NTT
Communication Science Laboratories is researching the implicit brain functions that are exhibited byathletes under these special conditions. Together with the Japan women’s national softball team, which
won the gold medal at the 2021 international sporting event held in Tokyo, NTT has been working onpractical initiatives in parallel with academic research to apply the findings of this research to improving
the team’s chances of winning.
Keywords: sports brain science, softball, pitching machine

1. Background of the initiative
The key to success in sports matches is the implicit
brain functions that even the athlete himself or herself
is unaware of, such as the instantaneous decisions
that must be made when batting in a game of softball.
The Sports Brain Science Project was launched at
NTT Communication Science Laboratories in January 2017 (in July 2019 it changed its name to the
Kashino Diverse Brain Research Laboratory). Its
mission is to push forward with research that
improves the performance of athletes on the basis ofclarification of the superior implicit brain functionsof top athletes and identification of the factors that
help them win [1] (Fig. 1). We have received thecooperation of US and Japanese professional baseballteams, Japanese semi-professional baseball teams,
university baseball teams, the Japan Softball Association (Japan women’s national softball team), andcorporate teams belonging to the Japan Women’s
Softball League. Therefore, we were able to clarify
the special abilities and characteristics of athletes
who compete at the topmost levels.
In October 2017, we signed a joint experimental
agreement with the Japan Softball Association tocarry out experimental and practical measurements of
NTT Technical Review

Vol. 20 No. 2 Feb. 2022

top and up-and-coming softball players. On August 3,
2016, before we entered into this agreement, the decision was made to reintroduce women’s softball to theinternational sporting event to be held three years
later in Tokyo. Alongside our academic research, wewere engaged in practical initiatives with the Japanese national team to devise a strategy for turning
brain training into success at softball with the aim ofwinning the gold medal at the event [2]. This article
focuses on the efforts we made with the Japan women’s national softball team to achieve this goal.
2. Working with the Japanese national
softball teamIn August 2016, Shinsuke Yabata, the then deputy
training manager at the Japan Softball Association,
paid his first visit to the Sports Brain Science Laboratory at the NTT Atsugi Research and Development(R&D) Center. The first time we met him, he told usthat Japan’s biggest challenge in winning the gold
medal would be dealing with fast and changing balls
thrown by US pitchers.
In September 2016, the Japan Cup was held in
Takasaki City, Gunma Prefecture. This provided us
with the opportunity to watch international matches
32

Feature Articles

Japan women’snational softball team

Improving theperformance of
top athletes
Actual match

Softball corporate teams
Major League Baseball(MLB)

Test match

Nippon Professional
Baseball (NPB)

Smart bullpen

Semi-professional
baseball
University baseball, etc.

Turning brain
training into
success at softball

Virtual reality
Basic experiment

Capture andcontrol implicit
brain functions

Clarifying the superior
implicit brain functionsof top athletesFig. 1. Sports Brain Science Project.

Line-of-sightmeasurement

SpatialmemoryBall-quality
measurement

Upper limb
movement
2019 NTT Atsugi R&D Center2017 Gunma

2017 Okinawa

2018 United States

2019 Kochi

2020 Guam, United States

Fig. 2. International matches and training camps.

among four national teams, including those of the US
and Japan. We then attended most of Japan’s international matches and obtained video footage of theteams as a member of the national team’s informationsquad (Fig. 2). Our main purpose in obtaining thismaterial was to understand the characteristics of thepitchers on opposing teams. We took videos of theirpitching styles from various angles to analyze pitchers’ habits. We also used a high-speed camera behind
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Vol. 20 No. 2 Feb. 2022

the back net to identify the characteristics of the balls
thrown by pitchers and conducted ball-quality analysis to extract the ball’s rotation axis and number ofrotations.
While we were analyzing the other teams in thismanner, we also attended the Japanese team’s training camps to take videos and assess the players. To
help the players improve their performance, we provided them with video feedback showing their
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Feature Articles

pitching and batting actions after a delay of a few
seconds and analyzed the performance of the pitcherswith the same high-speed camera technology that weused in the international matches. While providing
this support, we also conducted measurements forresearch purposes with the help of the players. At the
Okinawa training camp in December 2017, the top
national team who would compete at the target international sporting event and the national teams inother age groups (under-19, under-16, and under-14)
got together. We measured the hitting decisions ofplayers of each team during actual gameplay by using
virtual reality (VR). In June 2019, just before entering a long-term training camp, nineteen players fromthe top national team spent two days at the NTT
Atsugi R&D Center, where we conducted various
measurements including batting gaze, movement,
and cognitive tasks. We analyzed the measured
results as research data and provided feedback to theplayers.
3. Special abilities of top players
In women’s softball, the pitcher delivers the ball tothe batter from a distance of 13.11 m, which is about
two thirds the pitching distance in baseball. US pitchers pitch the ball at speeds ranging from 72 to 118
km/h with various pitch types, such as riseball,
dropball, curveball, and screwball, and the timing of
the ball to reach the batter can also be adjusted using
techniques such as change-up pitches. For some
pitchers, the difference between a riseball anddropball can be as much as 80 cm. However, the time
taken for a pitched ball to reach the batter is only
about 0.4 seconds. This only gives the batter a shortwindow of opportunity in which to respond by striking the ball. No matter how fast the batter can swing,
there is a limit to the batter’s ability to respond. It has
been found that good batters can adapt to this particular environment [3, 4].
There are several measures that batters can take todeal with these fast and varied balls. The first is toread the pitch sequencing. Although it varies fromperson to person, batters are generally able to read
pitch sequencing and narrow down the possible pitch
types to some extent before the pitcher throws theball. The second is to determine the pitcher’s habits.
For example, if a batter knows in advance that thepitcher sets the ball with the wrist in a different position when delivering a riseball, then she will be better
able to focus the strike on the position of this ball.
These pitching habits can be shared with the rest of
NTT Technical Review

Vol. 20 No. 2 Feb. 2022

the team through speaking and video.
However, not all pitchers are quite so easy to read.
We heard an interesting story about Eri Yamada, thecaptain of the Japan women’s national softball team.
She is widely recognized as a batter with the ability
to read a pitcher’s pitch sequencing, and unlike otherplayers, she seems to have the ability to identify different pitch types while sitting on the bench. However, it is not clear how she manages to do this.
Apparently, there are many things that she somehow
manages to understand. Even if she does not know
where or what the difference is, she can somehow
guess what type of pitch is coming and adjust her
striking accordingly.
Even more interestingly, experiments with VR suggest that even if she does not aware of what type ofpitch is coming, she can still sometimes react to it.
The VR experiments incorporated motion captured
from real pitches, and the batters were tasked withswinging a bat to strike randomly thrown change-up
and fastball deliveries. A sensor was attached to thebatter’s waist to measure the timing of the swing.
Using VR makes it possible to switch the correspondence between fastball and change-up of pitchingstyles and ball deliveries. As a result of carrying out
switches in this manner, we found that the batters
could swing their bats with the correct timing when
the correspondence between the pitching style andball delivery was correct, but could not with the correct timing more often when the correspondence wasswitched [5]. What is interesting is that the batters
said they could not tell the difference between different pitching styles and did not know what type ofpitch was coming from these pitching styles. Even
after the experiment, they were completely unawarethat the pitching styles had been switched. Thismeans that even if a batter is not aware of what she isdoing, she may be unknowingly using informationfrom the pitcher’s pitching style when striking a ball.
These types of predictions cannot be shared withthe team because they cannot be explained to others,
even when using video or data. However, if more
players can acquire these abilities, the team’s hitting
ability will improve.
4. Honing skills
As a member of the Japanese team at the 2000
international sporting event in Sydney, Reika Utsugi,head coach of the current Japanese team, conducted
image training by watching videos of opposing pitchers hundreds of times. Since visiting the NTT Atsugi
34

Feature Articles

R&D Center in May 2017 and experiencing VR batting simulations, she became very interested in theuse of this technology to defeat US pitchers.
At subsequent training camps, we brought in several times a VR system using footage and ball trajectories of pitchers from other countries that had beenacquired thus far. However, there were issues withthis system. At the level of a VR video game, it is possible to link the VR images with the swinging of a realbat, but there are still temporal and spatial discrepancies between the throwing of the ball in VR space andswinging of the real bat. It was therefore of limited
value for player training because it was not possible
to correctly assess whether the swings done by theplayers were actually appropriate. If we had pursued
greater accuracy, we would have had to install many
sensors and make the equipment much larger. This
would have made it difficult to find a location to set
up the equipment and placed more burden on theplayers; thus, making it difficult to use this approach
for actual training. In 2017, most VR headsets had tobe connected to a personal computer, but in 2019
stand-alone headsets became more widespread. With
such equipment, it became possible for players totrain individually in their hotel rooms. We began
preparations to bring this system to the athletes’ village during the international sporting event to be heldin 2020. Although allowing players to access thissystem in their rooms removes constraints related tolocation, it reduces its interactivity to the point where
the players can only watch footage and ball trajectories of pitchers. Being able to see ball trajectories inthree dimensions is better than watching the video,
but we were not sure how much this would benefit theplayers (Fig. 3).
5. The team’s secret weapon:
the “Nasu Machine”
In addition to the VR system, we also provided theplayers with a pitching machine for use in batting
practice. We called this the “Nasu Machine,” after Dr.
Daiki Nasu, one of the authors of this article. Besides
being able to deliver various types of breaking balls,
this pitching machine also displays images of apitcher, giving it the same appearance as a pitchingmachine at a batting cage that shows an image of apitcher. At the Kashino Diverse Brain Research Laboratory, we are using this machine to experimentallyinvestigate the perceptions of baseball batters underconditions that cannot be achieved with actual pitchers, such as switching them between left- and rightNTT Technical Review

Vol. 20 No. 2 Feb. 2022

June 2019

February 2020

Fig. 3. Our VR system.

handedness [6]. To conduct similar experiments with
softball batters, we had a pitching machine that could
reproduce various pitching speeds and ball rotation
speeds with softballs as well as baseballs. We decided
to try combining this softball-pitching machine with
the images of pitchers used in the VR system to createa practice machine with which players can actually
hit balls. At the end of the 2019 Atsugi visits, we
showed the players a prototype of this softball-pitching machine we had built in the laboratory andobserved that it could be useful in practice (Fig. 4).
However, we had a few issues with this machine
when it was used for actual training. Our biggest concern was that the equipment would be much larger
than the VR-only equipment, so it could be difficult
to find somewhere to install it. Since the pitcher’s
image is displayed using a projector, it had to be very
bright for outdoor use. Furthermore, steps had to betaken to protect the machine from rain if used outdoors. Since the team’s training involved other activities besides practicing with the pitching machine, it
was important to ensure access from the groundwhere all the rest of training is conducted. If we set
up the machine at our laboratory in Atsugi, it would
be of no use because it is far from the training camp,
and the players would not have time to visit us before
the start of the target event.
In 2019, the Utsugi Stadium was built in Takasaki
City as a dedicated softball venue, and it was decided
that the Japanese team would hold a training camp
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Feature Articles

June 2019
The Japanese team checking out the prototype

November 2020

June 2021

Survey of pitching machine installation location

Pre-event training camp

Fig. 4. Pitching machine.

there just before the target event. A covered practicearea for use in rainy weather was set up in one cornerof this facility. This was our preferred location for
installing the pitching machine, but since the sides ofthis area are just covered by netting and semi-exposedto the outside, we were concerned that daylight coming in from the sides might make it hard to see thepitcher images. On a more practical note, we fearedthat this machine might not be allowed to occupy apart of the training area that plays an important rolein wet weather. At the time, we had no idea how useful this machine would be.
Due to the novel coronavirus (COVID-19), the2020 international sporting event was postponed for ayear. As a result, we adjusted our schedule and moved
the preview of our machine from April 2020 toNovember 2020 when we finally loaded the projector
into a car and took it out for a field test. On this occasion, the machine was trialed by head coach Reika
Utsugi and some players, Yutaka Miyake (presidentof the Japan Softball Association), Taeko Utsugi (vicepresident of the Japan Softball Association), Shinsuke Yabata (training manager), and Noriko Yamaji(coach), who were able to see how the video images
looked, and were confident that the machine would
work fine in this location.
For the pitcher images, we were able to use thesame images that we had prepared for the VR system.
Unlike the VR system, we were not able to perfectly
reproduce the ball trajectories with the pitching
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machine. Specifically, the three-roller mechanism
used in this pitching machine is physically unable toreproduce gyro spin components. It also varies the
trajectory and rotation from one pitch to the next.
Bearing in mind the performance limits of this pitching machine and how it would be used in actual training, we decided to label pitching styles with different
pitch types and associate these labels with the ball
trajectories set in accordance with each pitch type.
As mentioned above, the characteristics of thepitching machine made it impossible to impart gyro
spin to the ball, so it was not possible to exactly reproduce the rotation of balls thrown by actual pitchers.
Therefore, under the guidance of team analyst Minori Ota, we adjusted the pitching machine to produce
the trajectories closer to those of deliveries made bya real pitcher by using the vertical and horizontal
rotations that the pitching machine was capable ofproducing. Ms. Ota watches every game from behindthe back net and is familiar with the data that havebeen gathered in relation to individual characteristicsof pitchers. This enabled her to provide us with very
detailed instructions on the variation of each pitcher.
We installed the pitching machine at the indoor
training ground in Takasaki City on May 17, 2021,
which was the first day of the team’s first training
camp just before the target event. When we did so, we
found that the players (including head coach Reika
Utsugi) were more interested in it than we had imagined. Our initial plan was to spend about a week36

Feature Articles

setting up the pitching trajectories, but on the following day, the players decided to start practicing with itstraight away. The first training camp was followedby the second training camp after a one-week break,and the machine stayed in place until the end of thissecond camp on July 14. Throughout both camps, theplayers took turns on the machine on visits from themain training ground. During this period, we also
added video footage of other pitchers, thus were able
to prepare content for six pitchers from three different
countries.
When the players came to the practice field where
the machine was installed, they told the operators
which pitchers and pitch types they were going topractice and practiced not only striking the ball but
also bunts and hit and run. One team member (YuYamamoto) said that when facing an actual pitcher,she experiences various emotions such as a desire to
strike the ball, but practicing on the machine was better because she could observe the pitcher’s pitchingstyles and ball trajectory more calmly. The players
also seemed to enjoy playing against virtual pitchers
and were keen to try out new video images and pitch
types as soon as we added them.
Since the team’s policy was not to disclose any
information about practicing with this machine until
after the finals at the target event, it was described as
the team’s “secret weapon” in newspapers and television reports until after they had won the gold medal.

about the combination of ball trajectories and pitching styles of opposing pitchers but helped them getused to the timing and the trajectories of balls thrownby opposing pitchers. It could also have positive psychological effects by making players better prepared.
Although it is impossible to identify exactly how ourmachine benefited the players and to what extent, weare confident that it did have a positive effect. At thevery least, it seemed that the players enjoyed using
this machine and had a positive attitude toward using
it as a practice tool. As mentioned by training manager Shinsuke Yabata in the October 2021 issue ofSoftball Magazine, a player called Saki Yamazaki,
who had thrown no-hitters in previous games, hit a
double in the final with a dropball thrown by Cat
Osterman of the US team. He commented that thepractice sessions with our machine may have contributed to this achievement.
It is not easy to pursue academic research and theimprovement of sporting performance at the sametime. In the initiatives introduced in this article, wewere probably more focused on improving performance than on conducting research. However, thefact that our research tools played a role in this successful bid for the gold medal proves that our experimental environment is properly connected to actual
matches. We will continue conducting research toelucidate and train the special abilities that athletesdemonstrate in actual matches.

6. Japan brings home the gold medal

References

Throughout the tournament, the Japanese team batted well. We cannot tell how much they were helpedin this achievement by being able to practice with
their secret weapon. In addition to coaching eachplayer in preparation for the event, the top pitchers
from the Japanese men’s softball team acted as batting pitchers to prepare the players for fastball deliveries from the US team. The team was also assisted
by analysts, but since they were unable to work onsite due to the COVID-19 pandemic, they instead
used the Internet and other sources to obtain information about opposing pitchers and analyzed their habits, pitch types, and pitch sequencing. The team also
took part in other efforts, initiatives, and actions thatcannot be described here, and the team won the gold
medal through the combined effect of all these
efforts.
Our pitching machine not only helped players learn

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Vol. 20 No. 2 Feb. 2022

[1]
[2]

[3]

[4]

[5]

[6]

“Feature Articles: Research and Development in Sports Brain Science,” NTT Technical Review, Vol. 16, No. 3, 2018.
https://www.ntt-review.jp/archive/2018/201803.html“Focus on the News: Japan Softball Association × NTT Collaboration
Results,” NTT Technical Journal, Vol. 30, No. 3, pp. 55–57, 2018 (inJapanese).
https://journal.ntt.co.jp/backnumber2/1803/files/JN20180355.pdf
D. Nasu, M. Yamaguchi, A. Kobayashi, N. Saijo, M. Kashino, and T.
Kimura, “Behavioral Measures in a Cognitive-motor Batting Task
Explain Real Game Performance of Top Athletes,” Front. Sports Act.
Living, pp. 1–9, 2020.
D. Nasu, “Timing Adjustment of Baseball Batters Determined from
Motion Analysis of Batting,” NTT Technical Review, Vol. 16, No. 3,
2018.
https://www.ntt-review.jp/archive/ntttechnical.php?contents=
ntr201803fa3.html
T. Kimura, D. Nasu, and M. Kashino, “Utilizing Virtual Reality to
Understand Athletic Performance and Underlying Sensorimotor Processing,” Proceedings, Vol. 2, No. 6, 299, 2018. https://doi.
org/10.3390/proceedings2060299
D. Nasu, T. Kimura, and M. Kashino, “Do Baseball Batters Perceive
Straight Ball Trajectory as Straight?”, 2020 NASPSPA (North American Society for the Psychology of Sport and Physical Activity) Virtual Conference, June 2020.

37

Feature Articles

Masumi Yamaguchi

Senior Research Scientist, Supervisor, Group
Leader of Molecular and Bio Science ResearchGroup of NTT Basic Research Laboratories, BioMedical Informatics Research Center and Kashi­no Diverse Brain Research Laboratory of NTT
Communication Science Laboratories.
He received a B.S. in physics from Kanazawa
University in 1998 and M.S. and Ph.D. in physics
from Kyoto University in 2000 and 2003. He
joined NTT Basic Research Laboratories in
2003. His research interest is in the means ofusing technology and data for improving humanperformance. He is a member of the PhysicalSociety of Japan, the Japan Society of Applied
Physics, and the Institute of Electronics, Information and Communication Engineers (IEICE).

Toshitaka Kimura

Senior Research Scientist, Kashino Diverse
Brain Research Laboratory, NTT Communication Science Laboratories.
He received a Ph.D. in human neurosciencefrom the Graduate School of Arts and Sciences,
the University of Tokyo, in 2003 and joined NTT
Communication Science Laboratories the same
year. He has been engaged in research on sensorimotor control and action-perception interaction
in humans. He has recently been focusing on
brain functions in athletes and the use of ICT in
sports. He is a member of the Society for Neuroscience, the Japan Neuroscience Society, and
IEICE.

Takehiro Fukuda

Daiki Nasu

Research Scientist, Kashino Diverse Brain
Research Laboratory, NTT Communication Science Laboratories.
He received a Ph.D. in medicine from the
Graduate School of Medicine, Osaka University,
in 2014 and joined NTT Communication Science
Laboratories in 2016. He has been engaged inresearch on human motor control and biomechanics in sports. He has recently been focusing
on the relationship between sports performanceand brain function in athletes. He is a member of
the Society for Neuroscience, the Japan Societyof Physical Education, Health and Sport Sciences, the Japanese Society of Biomechanics, andthe Japan Society of Baseball Science.

Dan Mikami

Associate Professor, Kogakuin University.
He received a B.E. and M.E. from Keio University, Kanagawa, in 2000 and 2002 and Ph.D. inengineering from the University of Tsukuba,
Ibaraki, in 2012. He worked for NTT from 2002
to 2021. He has been his current position sinceApril 2021. He is a visiting researcher at Kashino
Diverse Brain Research Laboratory of NTT
Communication Science Laboratories and visiting associate professor at Keio University. His
research interest includes computer vision andinformation and communication technology(ICT)-based assistance of motor-learning. He is amember of IEICE, the Information Processing
Society of Japan, and the Institute of Electricaland Electronics Engineers.

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Vol. 20 No. 2 Feb. 2022

Project Researcher, The University of Tokyo.
He received an M.A. in sports science fromWaseda University, Tokyo, in 2016. He worked
for NTT from 2017 to 2021. He has been his current position since January 2022. He is a visiting
researcher at Kashino Diverse Brain ResearchLaboratory of NTT Communication Science
Laboratories. He has recently been focusing on
the relationship between physiological states andperformance in sports. He is a member of theNorth American Society for the Psychology ofSport and Physical Activity and the Japan Society of Baseball Science.

Makio Kashino

Director of Kashino Diverse Brain ResearchLaboratory, NTT Communication Science Laboratories.
He received a B.A., M.A., and Ph.D. in psychophysics from the University of Tokyo in 1987,
1989, and 2000 and joined NTT in 1989. He iscurrently a visiting professor at the Graduate
School of Education, the University of Tokyo. He
has been investigating functional and neuralmechanisms of human cognition, especially
auditory perception, cross-modal and sensorimotor interaction, and interpersonal communication.

38

Feature Articles: 2021 International Sporting Event and
NTT R&D—Technologies for Supporting Athletes

Cycling × hitoeTM: Dialogue with the
Body via Surface Myoelectric
Potentials
Kentaro Tanaka, Shingo Tsukada,and Masumi Yamaguchi
Abstract

For athletes, knowing the state of their muscle activity is key to improving their performance andmaintaining peak performance. Using the surface myoelectric potential, which can be measured from thesurface of the body, is an effective method for understanding muscle activity with little physical burden.
Technology using hitoeTM, a functional fabric for collecting biosignals (jointly developed by NTT and
Toray Industries, Inc.), for measuring, visualizing, and analyzing surface myoelectric potentials of top
cyclists is introduced in this article. This technology is expected to be used for not only top athletes but
also for self-analysis by ordinary people participating in daily sporting activities.
Keywords: wearable devices, biometric signals, visualization of muscle activity

1. Introduction
Sensor information captured using power meters,
heart-rate monitors, and other devices is actively used
for training cyclists. Objective data showing physicalinformation and training progress of top athletes areimportant clues for not only improving performancebut also checking fatigue and injuries to maintainpeak performance. Our goal is to evaluate the dexterity of movement and state of fatigue of an athlete
from surface myoelectric potentials obtained fromthe skin covering the muscles and use the evaluation
results for data-driven training concerning sports andrehabilitation. Surface myoelectric potentials, which
can be measured from the surface of the body, provide athletes with data that are easy to acquire. We areresearching and developing a usability-aware systemthat integrates wearable sensors and applications
under the assumption that the system will be used fordaily training and in daily life.

NTT Technical Review

Vol. 20 No. 2 Feb. 2022

2. Measuring surface myoelectric potentials byusing hitoeTM
To measure the surface myoelectric potentials,
hitoeTM, a functional fabric for collecting biosignals(jointly developed by NTT and Toray Industries,Inc.), is used as a bioelectrode. One of the advantagesof hitoeTM is the ease of movement and placement of
the electrode. Conventional myoelectric sensors
encounter problems such as detachment of electrodes
due to sweat, long preparation time for affixing individual electrodes, and interference with the movement of the athlete in question. For myoelectricmeasurement using hitoeTM, since hitoeTM is attachedin advance to the lining of the training wear, the electrode simply contacts the skin when the clothing is
put on and will not detach. In sports such as cycling,
the cyclist usually wears training clothing thatadheres to the skin, and the compression necessary
for fixing the electrode to the skin can be secured.
Therefore, hitoeTM does not interfere with the normal
sensations and movements of the cyclist.

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Feature Articles

Photo 1. Eiya Hashimoto, a member of Team Bridgestone Cycling.

Lateral vastus lateralis
muscle (right leg)

Frequency (Hz)

140
120

a=−0.04, b=85.97, r=−0.55

Decrease in mean frequency of surface
myoelectric signals (= fatigue)

100
80
60
0

50

100

150
Time (s)

200

250

300

Fig. 1. Example of analysis of hitoeTM surface myoelectric potential data obtained during a time trial.

3. Evaluation of differences in pedaling styles on
the basis of muscle fatigue and muscle activity
of cyclists
To measure surface myoelectric potentials during
cycling by using hitoeTM, we evaluated the pedalingof cyclists on the basis of the muscle fatigue andmuscle activity of top cyclists in Japan, including
Eiya Hashimoto (Photo 1), a member of Team
Bridgestone Cycling, during a joint experiment withNTT DATA. In the experiment, cyclists pedaledunder various conditions, and from the collected pedNTT Technical Review

Vol. 20 No. 2 Feb. 2022

aling data, we identified points to be enhanced incompetition, provided feedback on the basis of differences in the way each cyclist pedaled, and held discussions that included the subjective feedback of thecyclists.
Surface-myoelectric-potential data obtained during
a time trial at the Izu Velodrome, which was used as
the venue for the international sporting event in 2021,
is shown in Fig. 1. The temporal variation of the meanfrequency component of the surface myoelectric signals is shown. The frequency component changes asmuscle fatigue progresses. It is clear from the figure40Low intensity

Vastus lateralis muscles
EMG voltage (µV)

High intensity

Vastus lateralis muscles
EMG voltage (µV)

Feature Articles

400
300
200
100
10

11

12

13

14

15

16

350
300
250
200
150
100
50
10

11

12

13

14

15

Seconds
EMG: electromyogram

Fig. 2. D ifferences in timing of muscle activity of the right and left vastus lateralis muscles during high- and low-intensity
pedaling.

that the mean frequency of the surface myoelectric
potential of the vastus lateralis muscle (the muscle of
the anterolateral thigh), which is a main muscle
group, decreases over time. Since multiple muscles
contribute to pedaling, the muscle areas that show
this tendency and the degree of change vary according to race strategy, difference between the left andright legs of the cyclist, and difference in pedalingstyle. When the interpretation of the objective data
matches the challenge facing the cyclist, such as identifying the muscles that tend to fatigue in the second
half of the race, we can provide new insights for thecyclist.
A case study involving Eiya Hashimoto, whoreceived feedback through insights, is described asfollows. Inconsistency was observed in the timing
and duration of muscle activity when pedaling undera higher load than normal. As shown in Fig. 2, themuscle-activity time of the vastus lateralis muscle of
the right foot was longer than that of the left foot, andthat time difference resulted in a delay in pedal
strokes. When he was given feedback on this point, hefelt that this muscle was prone to fatigue during races
and was surprised that the difference in his muscleactivity pattern could be read from the objective data.

NTT Technical Review

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This led to specific feedback such as being aware of
the timing of the activity of the vastus lateralis muscle
and the length of the pedal strokes during daily training.
We also analyzed how much muscle activity
changed on the basis of the difference between indoor
and outdoor environments, pedaling speed, and load,and verified the validity of the data through discussions with the cyclists. For meaningful discussion
and self-feedback between coach and cyclist, it isimportant to visualize the data and provide the analysis results promptly after training. Accordingly, forthis experiment, we developed a hitoeTM-based system for measuring surface myoelectric potentials instages and shortened the feedback cycle to the cyclist
after the measurement (Fig. 3).
To establish this system in the field of sports, wemust address the practical issues of finding moreeasy-to-understand indicators that allow the user tounderstand their issues and the effects of training aswell as making it even easier to use than it is now. We
are addressing these issues and will continue ourresearch and development with the aim of creating atool that can be used in everyday sports.

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Feature Articles

Measurement tool

hitoe™

Dashboard

Smartphone app

Analytical technology
Noise removal & feature calculation

Analysis + visualization
Myoelectric potential
waveforms

Output reportComparison with other sensor data

Muscle site 1

PowerGPS data
Speed

Muscle site 2

Elevationetc.

GPS: Global Positioning System

Fig. 3. System using hitoeTM for measuring surface myoelectric potential.

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42

Feature Articles

Kentaro Tanaka

Research Engineer, Bio-Medical Informatics
Research Center, NTT Basic Research Laboratories.
He received a B.E. and M.E. from the University of Tsukuba, Ibaraki, in 2010 and 2012. Sincejoining NTT in 2012, he worked as a member of
NTT Software Innovation Center and engaged inresearch and development of cloud computing
and distributed computing systems. Since 2019,he has been with NTT Basic Research Laboratories and Bio-Medical Informatics Research Center, where he is engaged in biosignal processing
and medical big data analysis.

Shingo Tsukada

Masumi Yamaguchi

Senior Research Scientist, Supervisor, Group
Leader of Molecular and Bio Science ResearchGroup of NTT Basic Research Laboratories, BioMedical Informatics Research Center and Kashino Diverse Brain Research Laboratory of NTT
Communication Science Laboratories.
He received a B.S. in physics from Kanazawa
University in 1998 and M.S. and Ph.D. in physics
from Kyoto University in 2000 and 2003. He
joined NTT Basic Research Laboratories in
2003. His research interest is in the means ofusing technology and data for improving humanperformance. He is a member of the PhysicalSociety of Japan, the Japan Society of Applied
Physics, and the Institute of Electronics, Information and Communication Engineers.

NTT Fellow, NTT Basic Research Laboratories, Bio-Medical Informatics Research Center.
He graduated from Toyama University Schoolof Medicine and received a medical license in1990 and Ph.D. in medicine from the Universityof Tsukuba, Ibaraki, in 2003. He was a visiting
researcher at the University of California San
Diego from 2003 to 2005. He joined NTT Basic
Research Laboratories in 2010 as a research
specialist. He has been studying cardio vascularfunction and neuronal regulation. His current
interests include the detection of biomedical
signals and functional modification using novel
wearable-type and implant-type bioelectrodes
based on the composites of conductive polymers
with various fibers and textiles. He is an inventorof the textile-based bioelectrode called hitoeTM.
He is a member of the Physiological Society ofJapan, the Japan Society of Applied Physics, theJapanese Circulation Society, the Japanese
Orthopedic Association, and the Japanese Association of Rehabilitation Medicine.

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43

Feature Articles: 2021 International Sporting Event and
NTT R&D—Technologies for Supporting Athletes

Swimming × Online Coaching:
Online Conditioning of Competitive
Swimmers—Focusing on theThorax—via Smartphones andWearable Sensors
Shingo Tsukada and Yumiko Hamaguchi
Abstract

In response to the decline in motor function (centered on the thorax) caused by chronic muscle tension
associated with strengthening exercises for competitive swimmers, we devised a training program that
promotes awareness of the functional coordination of the thorax; spine, ribs, and core muscles, andrestores natural and efficient body movement. This article presents the results of supporting athlete training during the novel coronavirus pandemic by providing regular coaching remotely using a web-conference system with smartphones, video recording, and a multi-sensor belt equipped with hitoe TM formeasuring myoelectricity, respiration, and motion.
Keywords: online core training, wearable sensor, hitoeTM

1. Background and target
For Japanese athletes to achieve success in international competitions, it is necessary to strengthen theiroverall physical fitness, including sufficient muscle
strength and energy metabolism to compensate forthe difference in body size compared with non-Japanese athletes. Satisfying this requirement requires
long-term, high-intensity training.
Athletes who have undergone long-term strengthening exercises have suffered from joint pain, stiffening of developed muscle groups, and limited range of
motion—all caused by accumulated fatigue and damage—that have resulted in poor performance anddisappointing results.
Regardless of the athletic discipline, pain and limited range of motion are not limited to the major
joints of the extremities and their regions; they canalso be found in the thoracic spine, thoracolumbar
junction, costovertebral joints, intercostal muscles,
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and around the shoulder girdle (Fig. 1). These parts
are remote from the major muscles and joints, so they
are easily overlooked. However, for swimmers, theeffects of limited range of motion and pain due tochronic muscle tension in these parts can lead toincreased water resistance in the streamline position
due to poor posture, such as the compensatory lumber
hyperextension. It has also been a concern that such
pain and limited motion could affect overall performance because they could limit the expansion of thethorax (ribs), which is associated with breathing. To
address this issue, we have been supporting competitive swimmers through regular conditioning to alleviate functional limitations and distortions of the joints
and muscles around the thorax, evaluation using biometric sensors and video, and online coaching via asmartphone.
The target swimmers, whose training base is at theswimming club of Chukyo University (head coach:
Yuichiro Sasaki), were Takeshi Kawamoto (Toyota
44Feature Articles

Around the shoulder girdle
Costovertebral joint
Thoracicspine

Intercostal muscles

Thoracolumbar junction

Fig. 1. F avorite sites of pain, muscle stiffness, andlimitation of movement (the back in red).

Motor) and Ai Soma (MIKI HOUSE) who have both
won top prizes in domestic competitions and participated in international competitions (butterfly sprint).
The pre-intervention subjective symptoms werechronic back muscle tension (Fig. 2(a)), middle backpain, and hardness of the thorax during breathing.
The objective symptoms were restrictions in all directions throughout the thorax, excessive contraction ofmuscles around the scapula and erector spinae muscles, and a tendency of lumber hyperextension. In
terms of whole-body coordination, the limited extension range of motion of the thoracic spine and hyperextension of the cervical spine and lumbar-sacral
junction during whole spine extension in the prone
position were observed (Fig. 2(a)). Limited range of
motion of spine extension was also confirmed in theback line (side view) in the streamline position (Figs.
2(c) and (d)). Similar symptoms re-occurred due tointensive strengthening practice.
2. Concept of coaching
The thorax is a three-dimensional structure consisting of stacked vertebrates of the thoracic spine, eachof which is connected to a pair of ribs on the left andright sides, which are joined by many joints and act
like a suspension. The thorax is an important part ofthe body that fine-tunes the movements of the wholebody. Accordingly, instead of focusing on simply
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gaining flexibility, we thus focused on how toenhance its function in coordinating the whole body.
First, the whole body is prepared to work as one byco-contracting the components of the inner unit (i.e.,
diaphragm, multifidus, transversus abdominis muscles, and pelvic-floor muscles). The swimmers weretrained to move their ribs and the linkage of the rib
cage voluntarily when moving the whole body. By
the swimmers self-checking the movement of theirribs by watching a video during the movement andrepeating self-correction with attention (Fig. 3), it
became possible to move involuntarily in the correctmanner.
3. Actual coaching
Following the step-by-step exercise plan listed
below, individualized hands-on and online coaching,lasting approximately 45 minutes once every 1 to 2
weeks, was provided to the swimmers. The basic
movements were first limited to those around one
axis, and only one part of the body was moved tomake it easier for the swimmers to become aware ofit. After the movements that separate the stabilizing
part (lumbar pelvis) from the ribs (thorax) werelearnt, the number of moving parts was gradually
increased to two or more. The number of planes andaxes of movement were then increased. The swimmers increased their endurance by changing their
posture while applying their body weight, performing
the movements under unstable conditions, and changing the speed at which they moved.
(1) Awareness of inner unit (i.e., body axis)
The swimmers were coached to correctly understand their inner unit (i.e., pelvic-floor muscles,
transversus abdominis muscles, multifidus muscles,
and linked diaphragm). While maintaining the stability of the lumbar pelvis and checking their awarenessof breathing and the contraction of the transversus
abdominis muscles, the swimmers slowly repeatedsmooth movement of the hip joints. This procedure isdone in supine, sitting, all-fours, and standing positions.
(2)	Relationship between rib movement and innerunit
The swimmers were coached to understand thebasic movements of their ribs (associated with thoracic-spine flexion, extension, lateral flexion, androtation) by placing their hands on their ribs and performing self-tactile movements (i.e., self-correcting
and guiding body movements). While keeping the
lumbar pelvis stable, the swimmers moved their ribs
45

Feature Articles

(a)

(c)

(d)

(e)

(b)

(a) Restriction of extension range of motion of the thoracic spine (yellow arrow, dotted line) and hyperextension of the cervicalspine and lumbar-sacral junction (white arrow) in whole spine extension in prone (push up)(b) Condition improved by regular conditioning(c), (d) Limited range of motion of spine extension in streamline position(e) Improved state
Red arrows in (d) and (e) indicate measurement of chest girth with the multi-sensor belt.

Fig. 2. Deterioration and improvement in functionality of the thorax.

(a) Linkage structure between thoracic
spine and pair of ribs. Movement of thethoracic spine and rib rings during
rotation of spinal column. Rib rings
rotate in the opposite direction.

(b) In the sitting position, the swimmer
fixes the pelvis and lumbar spine andplaces fingers on the ribs on both sides
to feel the movement of the rib rings
during rotation of the spinal column.

Fig. 3. Concept of coaching.

while maintaining awareness of their breathing andunderstanding the relationship of that movement tothe area of the rib cage into which the thorax expands(Fig. 4).
NTT Technical Review

Vol. 20 No. 2 Feb. 2022(3)	Consciously move the spine, shoulder joints, hipjoints, and other parts of the body in a state ofwhole body connection
The swimmers were instructed to maintain a state46

Feature Articles

Fig. 4. In the supine position, the swimmer fixes the pelvis, places fingers on the ribs on both sides, and moves the thoracic
spine to feel the movement of the ribs while consciously breathing.

Fig. 5. T he swimmer moves the rib cage (ribs and thoracic spine) while maintaining a state of “whole body connection” on
the mat.

of whole body connection (a state in which awarenessof the inner unit, hip-joint stability, shoulder-bladestability, abdominal and back muscles, etc. are allconnected and controlled) and to link the whole bodywhile maintaining awareness of rib movement(Figs. 5 and 6).

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4. Video evaluation of thorax function andbiometric measurement using wearable sensors
We created a multi-sensor belt (for research)equipped with hitoeTM electrodes for myoelectricmeasurement, 9-axis motion sensors (i.e., 3-axis
acceleration, 3-axis gyro, and 3-axis orientation measurements), and a stretch sensor for measuring expansion and contraction of the chest girth during
47

Feature Articles(a) Extension of thoracic spine
The pelvis is stabilized, centrifugal contractionof the psoas major muscle and rib movement
are induced, and the swimmer is made awareof thoracic extension. Blue arrows indicate thedirections of “eccentric contraction” of muscles.

(b) Application of extension + rotation
The lumbar spine is not extended, but theintervertebral space is widened. Blue arrows
indicate the directions of “eccentric contraction”
of longitudinal muscles. Red arrow represents
the direction of thoracic rotation (upward twisting).

Fig. 6. Lunge with non-stretch straps.

respiration for measuring the swimmers’ bodies. The
data were transferred to the smartphone via BLE(Bluetooth Low Energy) and stored in the internal
memory of the smartphone (Fig. 7). A dedicatedhitoeTM belt (waterproof and multi-sensor type; forresearch) was used for underwater measurement ofelectromyograms, heart rate, and motion (Fig. 7(e)).
5. Evaluation of thorax function with swimmers
in streamline position
Ease of breathing and arm raising were evaluatedon a five-point self-assessment scale before and after
the above-stated exercise plan. The degree of thorax
expansion during respiration in the streamline position was also measured (i.e., continuous measurement of chest girth) by using the stretch sensor of themulti-sensor belt. The changes in the streamline position before and after the exercise were photographedfrom three directions and evaluated. The results indicate that the ease of breathing and arm raising
increased by one to two levels (on a five-point selfassessment scale) after the planned exercise. Over thecourse of the postural changes, we found that initially,
the swimmers had a tendency toward lumber hyperextension and extension of the thoracolumbar junc-

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tion; however, this tendency also gradually improved(Figs. 2(b) and (e)).
6. Online coaching using video conferencing
via smartphones
Due to the novel coronavirus (COVID-19) pandemic, the international sporting event due to be heldin 2020 was postponed for one year. Accordingly, toprevent the spread of COVID-19 infections, access to
Chukyo University, the main training site, and swimming facilities where training camps were held wasrestricted. To continue regular conditioning of theswimmers, we switched from on-site hands-on
instruction to online coaching via a smartphone video-conferencing system. Since the swimmers had
already mastered the basic movements throughhands-on coaching, we gradually upgraded theadjustments and techniques used in the online
instruction by (i) determining the current state of theswimmers through dialogue and the above-mentioned
evaluation indicators as well as their body movements from the video images and (ii) adjusting thecoaching content accordingly. Conditioning throughonline coaching was helped by the motivation of theswimmers and continued until the main competition48

Feature Articles(c) Example measurement of
motion of the rib cage (earlystage of chest training)(a) Multi-sensor belt: back
(Dotted-line box indicatessensor housing)(d) Example measurement of
motion of the rib cage(after training)(b) Multi-sensor belt: front(Stretch sensor for measuring
central chest circumference)(e) Example of electromyogram of the quadriceps muscle acquired withthe hitoeTM belt for underwater measurement

Fig. 7. Example measurements with a sensor for measuring multifunctional motion (for chest).

in 2021 over a period that included overseas expeditions and training camps.
7. Discussion
Swimmers must maintain a streamline position toensure lower resistance while moving through thewater. As well as achieving sufficient range of motionof the shoulder joint, they must satisfy two requirements: (i) coordination of many muscles involved inthoracic extension, especially control of the small
muscle groups (local muscles) at the deep segmental
level of the spinal column (such as multifidus androtator muscles) and (ii) sufficient elongation of theperi-scapula muscles, erector spinae muscles, breathing-related muscles, latissimus-dorsi muscles,
abdominal oblique muscles, etc. (collectively known
as the global muscles).
It has been suggested that as a result of high-intensity training, stress concentrates on relatively fragile

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structures and tissues through fatigue or injury. This
concentration of stress then triggers local inflammation and pain, which creates a vicious cycle throughthe neuromuscular and vascular control systems,
resulting in chronic pain and impaired functions.
Regular conditioning focused on the rib cage caneffectively bring out the natural functions of this area
while making the swimmer aware of the connectionof the whole body and their overall condition.
Takeshi Kawamoto set a new personal best in the
50-m butterfly at the Japan Championships and competed as a member of the 100-m-butterfly team at thetarget international sporting event in 2021. Ai Soma
won the 50-m and 100-m butterfly at the Japan Short
Course Championships. Knowing that athletes needto strengthen their physical, technical, and mental
strength while coping with fatigue and potential dysfunction associated with rigorous training, we willcontinue to support them by enhancing recovery andconditioning techniques.

49

Feature Articles

Shingo Tsukada

NTT Fellow, NTT Basic Research Laboratories, Bio-Medical Informatics Research Center.
He graduated from Toyama University Schoolof Medicine and received a medical license in1990. He also received a Ph.D. in medicine fromthe University of Tsukuba in 2003. He was avisiting researcher at the University of California
San Diego from 2003 to 2005. He joined NTT
Basic Research Laboratories in 2010 as a
research specialist. He has been studying cardio
vascular function and neuronal regulation. His
current interests include the detection of biomedical signals and functional modification
using novel wearable-type and implant-typebioelectrodes based on the composites of conductive polymers with various fibers and textiles.
He is an inventor of the textile bioelectrodehitoeTM. He is a member of the PhysiologicalSociety of Japan, the Japan Society of Applied
Physics, the Japanese Circulation Society, theJapanese Orthopedic Association, and the Japanese Association of Rehabilitation Medicine.

NTT Technical Review

Vol. 20 No. 2 Feb. 2022

Yumiko Hamaguchi

Director of Springs Pilates Inc.
She has more than 25 years experience as aphysiotherapist and has a certificate in the
National Certified Pilates Teacher and Polestar
Pilates Rehabilitation, GYROTONIC ® and
GYROKINESIS® method. She has been particularly interested in this whole-body integrated
approach to help clients deal with chronic pain,
trauma, and repetitive strain injuries. She has also
been responsible for conditioning training ofelite competitive swimmers since 2018.

50

Feature Articles: 2021 International Sporting Event and
NTT R&D—Technologies for Preparing the Event

Network Construction × Wearable
Heat Countermeasures
Kazuhiko Takagahara, Hiroyoshi Togo, and Naomi Nagai
Abstract

One of NTT’s key roles in the 2021 international sporting event held in Japan was the construction ofa large-scale network during the hot and humid Tokyo summer to provide a stable and secure communication environment. We built and installed a health-management system that involves wearable biological/environmental sensors to prevent heat-related health issues and enable construction work to be carried out more safely.
Keywords: heat countermeasures, wearable sensors, health management

1. Background and objectives
The numbers of deaths and emergency room visitscaused by heat stroke have been increasing due toclimate change and other factors, and this has becomea major issue for society in general. According to asurvey by the Fire and Disaster Management Agencyof the Ministry of Internal Affairs and Communications of Japan, 46,299 people required emergency
hospital treatment for heat stroke between June 1 andOctober 3, 2021, and according to the Ministry of
Health, Labour and Welfare of Japan, there were 829
cases of heat stroke at the workplace in 2020 resulting
in an absence of four days or more, of which 22 cases
resulted in fatalities. The Ministry of Health, Labourand Welfare and other organizations published guidelines and manuals on how to prevent heat stroke in theworkplace.
At NTT, we developed a method for implementing
heat-related health issue prevention measures forindividual workers by estimating health risks on thebasis of vital-sign data and issuing alerts when necessary. To verify the effectiveness of this method, we
conducted a demonstration experiment with thecooperation of NTT EAST. We monitored 49 construction workers in the Tokyo, Kanagawa, and Hokkaido areas for a total of 834 person-days in Augustand September 2020. We asked the construction
workers to fill out questionnaires about how hot or
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cool they felt while working, and we were able toconfirm the relationship between their estimatedinternal-body-temperature fluctuations and whether
they felt hot or cool.
2. Method for estimating health risks andissuing alerts
Our method estimates the risk of heat-related healthissues by means of logic for estimating changes ininternal body temperature,*1 which was created in a
new joint research project with Nagoya Institute ofTechnology (NIT). This logic is based on an original
program developed by NIT that combines electromagnetic field analysis and thermal analysis by taking into account factors such as a person’s internalbody-temperature regulation, clothing, and level ofactivity. In a joint experiment among NTT, Yokohama
National University, Shigakkan University, and NIT,
we conducted clinical experiments in the artificial
weather room at Shigakkan University that confirmed
the applicability of the logic for estimating internalbody-temperature fluctuations.*2 On the basis of thetheory of thermal and exercise physiology, we also
*1 Since the method described here is not a medical procedure, theexpression “internal body temperature” is used instead of “coretemperature.”*2 Shigakkan University Research Ethics Review Committee: Accession number 124.

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Feature Articles

Heart rate

Outdoor work

°C Temperature

Estimate internal-bodytemperature fluctuations

Humidity

Determine health risks

Physical condition ofeach worker

Sato

KoizumiKanekoKawanoIto

Kuno

Matsuoka

Remote monitoring

Alert
Indoor work
Tell worker to take a break

Fig. 1. Flow of our health-risk estimation method.

hitoeTM transmitter(TX02)

hitoeTM smart clothing

C3fit IN-pulse

hitoeTM shirt

hitoeTM belt
*Workers wear one of the above items

Fig. 2. Wearable biological/environmental sensors.

3. Wearable biological/environmental sensors

oped by NTT Device Innovation Center, we use
either a piece of C3fit IN-pulse clothing made by
GOLDWIN Inc. or a hitoeTM shirt or belt developedby Toray Industries, Inc. [1] (Fig. 2) to monitor various parameters including the wearer’s heart rate, R-R
interval, step count, and upper-body tilt.

Wearable biological/environmental sensors*3 areused to acquire an individual’s heart rate, temperatureinside clothing, and humidity. In addition to a TX02
transmitter marketed by NTT TechnoCross based on
wearable biological/environmental sensors devel-*3 This sensor is not a medical device. hitoeTM is a functional fabricdeveloped by Toray Industries, Inc. and NTT to collect biomedical
signals, which are weak electrical signals emitted from the body,with little burden on the wearer. The functional fabric hitoeTM
is a trademark of both companies.

created criteria for using internal-body-temperaturefluctuations and other factors to trigger alerts (Fig. 1).
Together, the estimation logic and alert criteria constitute our method for estimating health risks.

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52

Feature Articles

4. Operation support for the 2021 international
sporting event

health issues, such as heat stroke, among the construction workers.

By applying this method to construction work at
venues used for the international sporting event in
2021, we were able to prevent heat-related healthissues among construction workers, enabling theevent to be held safely and securely. From May 24 to
September 30, 2021, the health-management systemapplying this method was used by a total of twelve
construction workers at two sites [2]. In addition toremotely monitoring health risks, the system also
issued appropriate alerts to the construction workers
and their site managers based on the above-mentioned alert criteria. A total of ten alerts were issued
during this period. In each case, the site manager wasable to check the physical condition of the affected
construction worker and take measures such asencouraging them to take a break if necessary. As aresult, we were able to prevent the occurrence of

5. Summary

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At NTT, we will continue to deepen our knowledge
by introducing this method to more sites with the aimof ensuring that large-scale events around the world
can be held safely and securely.
References
[1]

[2]

K. Takagahara, Y. Hashimoto, K. Matsunaga, Y. Higuchi, N. Matsuura, K. Kuwabara, H. Togo, T. Kawahara, A. Hirata, H. Tanaka, and T.
Miyazawa, “Physical-condition Management Technology for Creating More Comfortable Work Sites,” NTT Technical Review, Vol. 19,
No. 6, pp. 48–54, 2021.
https://www.ntt-review.jp/archive/ntttechnical.php?contents=
ntr202106fa7.html
Press release issued by NTT TechnoCross, June 15, 2021 (in Japanese).
https://www.ntt-tx.co.jp/whatsnew/2021/210615.html

53Feature Articles

Kazuhiko Takagahara

Senior Research Engineer, NTT Device Innovation Center.
He received a B.S. in mechanical engineeringand M.S. in information science and technology
from the University of Tokyo in 2006 and 2008.
He joined NTT Microsystem Integration Laboratories in 2008, where he was engaged in researchand development (R&D) of optical and wirelesstelecommunication devices and vital sensing
devices. He is a member of the Japan Society ofApplied Physics.

Naomi Nagai

Senior Manager, Produce Group, Research andDevelopment Planning Department, NTT.

Hiroyoshi Togo

Senior Research Engineer, Supervisor, NTT
Device Innovation Center.
He received an M.Sc. and Ph.D. in applied
physics and electronic engineering from the
University of Tsukuba, Ibaraki, in 1996 and2010. He joined NTT Musashino Opto-electronics Laboratories in 1996. Until 2001, he wasinvolved in the development of the thermo-capillary waveguide-based optical switch and from2001 to 2002 endeavored to commercialize it for
NTT Electronics. From 2003 to 2015, he developed ultrawideband impulse radio systems using
photonic techniques and millimeter-wave tomography with electro-optic probing at NTT Device
Technology Laboratories. Since 2016, he has
been leading a wearable-device development
project to contribute to smart healthcare at NTT
Device Innovation Center. He is a senior memberof the Institute of Electrical and Electronics
Engineers (IEEE) Photonics, Antenna and Propagation, and Microwave Theory and Techniques
Society, and the Institute of Electronics, Information and Communication Engineers (IEICE) of
Japan. He was a finance director of the Councilof Technical Committee Representatives anddirector of the Technical Committee on Photonics-applied Electromagnetic Measurement in the
IEICE Communications Society. He is also anexpert member of the Technical Committee on
Microwave Photonics in the IEICE Electronics
Society and expert member of the Japan Electronics and Information Technology Industries
Association wearable electronics standardization. He received the 2006 Asia Pacific Microwave Photonics Conference AP-MWP Award,
the 2010 European Conference on Antenna andPropagation Award, and the Japan Wood
Research Society Best Paper Award 2013.

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54

Feature Articles: 2021 International Sporting Event and
NTT R&D—Technologies for Preparing the Event

Venue-management Staff × CUzo
Takahiro Kusabuka, Yuichi Maki, Takuya Gouda,
Akira Suzuki, Masaya Tamaru, and Takuya Indo
Abstract

For the 2021 international sporting event in Tokyo, NTT brought out a feature-distribution communication technology called CUzo and a mobile device with a transparent display called CUzo Card. This
article describes our work on this project, which sought to enhance the hospitality afforded at venues by
providing venue staff with information and communication technology tools to support the guidance
they provide to visitors, and the technology used in this project.
Keywords: CUzo, transparent displays, AR

1. Overview
The purpose of this project was to improve the hospitality provided at venues by using information andcommunication technology (ICT) to support theefforts of venue-management staff who provide guidance to visitors including athletes and spectators. It is
commonplace for people to use smartphones andtablets when dealing with inquiries, but they tend to
do so while constantly looking at the screen of theirdevice. This makes it difficult to properly engage incommunication with other people while understanding their intentions based on non-verbal cues such as
facial expressions and gestures. For this project, weused a system consisting of a feature-distribution
communication technology called CUzo and hand-

held device called CUzo Card with a transparent
display based on this technology (Fig. 1, Table 1)with which we implemented a communication stylewhereby venue-management staff could provide visitors with guidance while observing visitor expressions.
In 2021, this system was used at the international
sporting event in Tokyo and was provided with applications to support face-to-face translation (Fig. 2)
and facility guidance (Fig. 3). In face-to-face translation, the CUzo Card displays the translated content of
a conversation in a manner similar to subtitles, allowing two people to have a conversation while watching
the other person’s facial expressions and gestures atthe same time. When guiding visitors at a facility, thissystem can also be used to add visual annotations to

Front

Back

Fig. 1. A CUzo Card.

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Feature Articles

Table 1. CUzo Card specifications.
Item

Specifications

Remarks

Size

82×157×20 mm

Thinnest part: 8 mm, thickest part 22 mm

Weight198 g

Including battery

Fig. 2. Using the face-to-face translation app.

Fig. 3. Using the facility guidance app.

the user’s actual surroundings. However, the event
had to be held without spectators due to the COVID19 pandemic, but the system was nevertheless usedby approximately 250 venue-management staff tosupport attendees including event officials and athletes at three venues in Tokyo and the surrounding
regions for a total of 28 days.

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2. Applications
2.1 Facility guidance
When venue-management staff are showing visitors the way to their seats and on-site facilities, they
can provide clear guidance by holding up the CUzo
Card to provide annotations on the visitor’s actual
surroundings, including the location of the facility
and the route to their destination.
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Feature Articles(a) Face-to-face translation(b) Side-by-side translation

Fig. 4. Screenshot of the face-to-face translation app.

Previously, it would have been necessary to go
through the complicated procedure of searching forthe target facility on the basis of the information confirmed from a flat map while comparing this information with the actual scenery then rebuilding a mental
picture of the route. Some venues do not have signs
or facilities that can serve as landmarks, and even if
explanations are attempted using descriptive words
such as “the white sign,” this can still lead to difficulties where smooth guidance is not possible when bothparties understand these words as referring to different landmarks.
CUzo can solve this problem by superimposing
annotations on the user’s actual surroundings so thatthey can be seamlessly guided through the facility. In
this project, we prepared guides to show people totheir seats at sports events, and to other facilities suchas restaurants, stores, toilets, multi-purpose (barrierfree) toilets, prayer rooms, lounges, medical offices,
and automated external defibrillators.
2.2 Face-to-face translation
Although smartphone translation functions can beused to handle multiple languages, these functions
are not geared toward face-to-face conversations, but
it is assumed that both parties in a conversation are
speaking while checking their smartphones for thetranslated results. As a result, they end up being glued
their phones and more likely overlook the other person’s facial expressions and gestures, which are
regarded in conventional customer service as being
important for understanding what someone is reallytrying to say. To address this issue, we designed aninteractive system that allows users to view informaNTT Technical Review

Vol. 20 No. 2 Feb. 2022

tion while looking at the other person’s facial expressions through a transparent display. This system isused by holding up the display between the two participants in a conversation. When one of them speaks,
their words are translated into subtitles that are displayed where the other person can see the speaker’s
facial expressions and gestures together with thecontent of their speech (Fig. 4(a)). This system supported eight languages: Japanese, English, Spanish,French, Portuguese, Chinese (traditional and simplified), and Korean.
Due to the COVID-19 pandemic, it was felt thatpeople might be unwilling to engage in face-to-faceconversations, so we prepared the screen design
shown in Fig. 4(b) to enable people to converse in aside-to-side manner without having to flip the screen
around. Users can switch between the two screen
designs at the press of a button, allowing the system
to respond flexibly.
3. CUzo feature-distribution communication
technology and the CUzo Card
The CUzo feature-distribution communication
technology allows high-performance services to beaccessed through simple devices by using communication to link up with distributed functions deployedon a network. By keeping the devices simple, wewere able to address issues that can degrade the user
experience, such as lack of responsivity when thedevice is subject to increased processing loads, andwe were also able to improve the device’s battery
lifetime and reduce initial deployment cost. The
CUzo Card is a compact and lightweight device
57Feature Articles

Cloud
App server(facility guidance)

App server(face-to-facetranslation)

Maintenance &operation server
Maintenance &operation base
Maintenance &operation terminal

Network
System operator

Venue-management staff
Venue A

Venue-management staff
Venue B

Fig. 5. System configuration.

based on CUzo, incorporating the latest transparent
display technology. Since the CUzo Card has a transparent display, users can view information from bothsides of the display while looking through it at theiractual surroundings.
4. System
The system we provided for this project is shown in
Fig. 5. Venue-management staff carry CUzo Cards onneck straps and can assist visitors by communicatingwith them via facility guidance and face-to-facetranslation apps. The app server runs on the cloud,and the CUzo Card connects to this server via asmartphone over a Bluetooth® connection.
5. Results
Since the international sporting event went ahead in
2021 without any spectators, only the face-to-facetranslation function was used. However, the CUzo
Card was widely used for guiding foreign athletes
and staff. Over a 28-day period, approximately 3500
translations were carried out by approximately 250
venue-management staff members at three venues.
The system received favorable responses from users,
who not only thought it looked cool but also appreciated being able to see who they were speaking to.
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This was due to the attractive and convenient designof the device based around a transparent display, providing users with a tool that allowed them to converse
more naturally with other people while observing
their expressions.
Users also found the device easy to operate and use,confirming the utility of our user-experience designof enabling people to use the system without disrupting actual work situations. However, some venuemanagement staff members who used the system in
direct sunlight said that it was sometimes difficult to
see the screen, so we will need to consider the characteristics of the display when used outdoors.
Regarding the translation function, some users said
they were glad to be able to access other language
pairs besides Japanese and English, and the system
was welcomed by users who had few staff members
capable of speaking languages such as French or
Spanish. It was also pointed out that the speech-recognition results were sometimes inaccurate, and thatthe translated results sometimes took quite a while toappear, highlighting the need for improvements to the
speech-recognition/translation engine performanceand the bandwidth of the local network throughwhich the devices were connected.

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6. Summary
By applying our CUzo feature-distribution communication technology and our CUzo Card device
with a transparent display for providing guidance forvisitors to venues used during the 2021 international
sporting event, we were able to provide a system thatallows this sort of work to be performed moresmoothly. This system is expected to be useful in awide variety of customer-facing scenarios. Examples
include public transport facilities such as train sta-

Takahiro Kusabukations and airports, public amenities, and tourist facilities. Although in this case we asked the venue-management staff to use the system, the fact that theyfound it so easy to use suggests that CUzo Card could
also be carried by visitors and tourists while travelling or when visiting places such as art galleries andmuseums.
In the future, we intend to continue with our ICT
research and development to explore new experiences at places where people and information come into
contact.

Akira Suzuki

Research Engineer, NTT Human Informatics
Laboratories.
He received an M.S. in engineering from Ritsumeikan University, Shiga, in 2012 and joined
NTT in the same year. His research interests
include mainly user interface and human-computer interaction. In this project, he engaged inlaunching the project and is currently the techlead for the development of CUzo Card. He is amember of the Association for Computing
Machinery (ACM).

Senior Research Engineer, NTT Human Informatics Laboratories.
He received a B.E. from Gunma University in
1989. Since joining NTT in 1989, he has been
involved in R&D of facsimile communication,system development of communication terminals, and development of communication services. He participated in the Epoch-Making
Project from 2019 to 2021 and was responsible
for the application development and operation of
CUzo for the international sporting event held inTokyo in 2021.

Yuichi Maki

Masaya Tamaru

Research Engineer, NTT Human Informatics
Laboratories.
He received a Bachelor of Engineering and
Master’s of Information Sciences from Tohoku
University, Miyagi, in 2009 and 2011. He joined
NTT in 2011 and has been engaging in researchand development (R&D) of human-computerinteraction, mobile computing, and consumer
electronics. In 2019, he joined the 2020 EpocMaking Project, where he engaged in the application development of the CUzo mobile transparent display for event venue staffs.

Senior Research Engineer, NTT Human Informatics Laboratories.
He received a B.E. from Nihon University,
Tokyo, in 1997 and joined NTT the same year,
where he has been engaging in R&D of home
gateway, system development of home appliance
control, Internet of Things services development
for agriculture, etc. He participated in the EpochMaking Project from 2019 to 2021 and was thedevelopment leader of CUzo for the international
sporting event held in Tokyo in 2021. He is currently working for NTT EAST as an associatemanager, Office of Network Security Network
Business Headquarters.

Takuya Gouda

Takuya Indo

Research Engineer, NTT Human Informatics
Laboratories.
He joined NTT DATA in 2009 and has been
engaged in system development for the financial
industry. He was in charge of using CUzo for
staff of the 2021 international sporting event heldin Tokyo.

NTT Technical Review

Vol. 20 No. 2 Feb. 2022

Senior Research Engineer, Supervisor, NTT
Human Informatics Laboratories.
He received a B.S. in physics from Kyoto University in 1993. In the same year, he joined NTT.
His research interests include media processing
and human-computer interaction. He is a member of the Information Processing Society ofJapan, and ACM.

59

Feature Articles: 2021 International Sporting Event and
NTT R&D—Technologies for Making the Event Inclusive

Barrier-free Route Guidance ×
MaPiece®
Yusuke Ichikawa, Hirofumi Abe, Tatsuaki Ito,
Shunsuke Konagai, Satoshi Sakuma, Satoshi Fukada,and Shingo Kinoshita
Abstract

NTT developed Japan Walk Guide, a barrier-free route-guidance application for wheelchair users andother people with limited mobility. Japan Walk Guide provides one-stop barrier-free route information,
ranging from public transportation to walking routes, mainly based on barrier-free information collectedby volunteers. This article discusses an evaluation by wheelchair users of Japan Walk Guide launchedduring the international sporting event held in Japan in 2021.
Keywords: barrier-free, mobility support, walking-space network

1. Overview
We want wheelchair users to be able to movearound freely and enjoy watching sports. About 1900
volunteers gathered under the auspices of the All
Japan Business Committee to collect barrier-free
information with the aim of creating a society inwhich everyone can live comfortably without barriers. The information was collected over a wide areaof Japan, from Sapporo, Hokkaido Prefecture in
northern Japan, to Izu, Shizuoka Prefecture in central
Japan, and covered 41 sports stadiums, including theJapan National Stadium (Fig. 1), and 98 stations
nearest those venues. NTT has been supporting thecollection of barrier-free information not only fromvolunteers but also from a technical standpoint by
providing MaPiece®, a barrier-free information andcommunication technology developed by NTT laboratories.
The 2021 international sporting event held in Japandrew worldwide attention to barrier-free initiatives.
Through this event, NTT aimed to further expand theculture of a cooperative society through citizen participation by promoting the efforts of volunteers tocollect barrier-free information. To aid our efforts, wedeveloped a barrier-free route-guidance service for
NTT Technical Review

Vol. 20 No. 2 Feb. 2022

wheelchair users, called Japan Walk Guide, covering
the Japan National Stadium and other sports venues.
Barrier-free information used in this service was collected by the All Japan Business Committee andMinistry of Land, Infrastructure, Transport and Tourism. Japan Walk Guide was released by the All Japan
Business Committee for spectators and officials
watching the event from July 13, 2021 until September 5, 2021, when the target event ended. A photograph of a wheelchair user using the app is shown in
Fig. 2.
2. Japan Walk Guide
2.1 Service design of Japan Walk Guide
When we interviewed wheelchair users when wewere designing Japan Walk Guide, we found that they
all felt anxious about whether they could get to event
sites by public transportation and had to looked up a
great deal of information before going out.
Responding to concerns such as “Is there an elevator at the station I use?”, “Is the road from the station
to the venue flat?”, and “Is there a wheelchair-accessible restroom at the station or along the walking
route?”, wheelchair users must meticulously checkvarious services, such as websites of event organizers
60

Feature Articles

Map Data ©NTT InfraNet

Fig. 1. Map of the venues where information about the surrounding area was collected.

Fig. 2. A wheelchair user using Japan Walk Guide.

and transportation companies, map apps, and streetphoto provision sites, which has been a barrier towheelchair users.
Accordingly, Japan Walk Guide was designed as aservice providing necessary information—such as
public transport-transfer information from the station
closest to the departure point to the station closest to
the venue, information on barrier-free walking routes
from the station closest to the venue to the venue, andinformation on surrounding facilities that can be usedby wheelchair users such as multi-functional toilets
and rest areas, in a one-stop manner.
Considering the concept that we want people toenjoy going out without anxiety, we adopted a graphical design that creates a sense of enjoyment while
being creative in the use of colors and illustrations in
NTT Technical Review

Vol. 20 No. 2 Feb. 2022

the design of the screen (see Fig. 3 “(1) Start page”
for a screenshot of the key design).
Following the postponement of the target sporting
event due to the novel coronavirus (COVID-19) pandemic, we conducted more interviews with wheelchair users to investigate any change in their sense ofvalues concerning their mobility as a result of thepandemic. We learned that wheelchair users havealways tried to avoid congestion; however, during the
pandemic, their need to avoid congestion has become
even stronger. With that result in mind, we added afunction to Japan Walk Guide that provides information on station congestion so that wheelchair users
can move around with peace of mind by using stations when they are less crowded.

61

Feature Articles(1) Start page(2) Entire-route
search(3) Walking-route
guidance(4) Surrounding
information(5) Station-congestion
information

Fig. 3. Japan Walk Guide.

2.2 Details of Japan Walk Guide
Implemented as a web application, Japan Walk
Guide can be used instantly by following a URL (uniform resource locator) link that is read via a QR code
without the need to install a native application. It was
implemented in this manner because attendees at
sporting events would probably not use a dedicatedapp because of the high psychological barrier of
installing it just for a short-lived event. As a responsive service, the app can be used to either gather
information in advance on a personal computer athome or check information on a smartphone while on
the move. The details of each function of the app,
along with screen transitions when using the app, aredescribed below.
(1)	Entire-route search considering barrier-freewalking routes
Clicking the Start button on the start screen takes
the user to the search screen that includes public
transportation for the entire route. The search fortransfers on public transportation is linked with the“RakuRaku Odekake-net” (supported by the Nippon
Foundation) provided by the Foundation for Promoting Personal Mobility and Ecological Transportation(Eco-Mo Foundation). The RakuRaku Odekake-net
is a service that provides barrier-free information(such as barrier-free facilities in stations and transfer
information) for the elderly and disabled in an integrated manner. It is operated by the Eco-Mo Foundation and uses information about barrier-free transportation collected from transportation operators andfacility managers throughout Japan [1].
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Vol. 20 No. 2 Feb. 2022

(2) Walking-route guidance
In addition to the public-transportation route search
described in (1) above, the app also displays barrierfree route information covering the walking section
from the station to the target stadium. This function
allows the user to (i) specify the target stadium as thedestination or departure point and (ii) search theentire route in consideration of barrier-free information for the walking route (Fig. 3(2)). The barrier-freeroute is based on the “Transportation Plan V2” [2](published by the Bureau of Olympic and Paralympic
Games Tokyo 2020 Preparation of the Tokyo Metropolitan Government) combined with barrier-free
information collected by volunteers from the All
Japan Business Committee. As well as showing thebarrier-free route, it provides information about theroute (such as slopes and steps) along with photos of
the area collected by volunteers from the Committee.
With this information, users can confirm in advancewhether the route is passable in accordance with thedegree of their disability (Fig. 3(3)).
(3) Information about the surroundings
Clicking the Surroundings map button on thewalking-route guidance screen switches to the surrounding information screen. In addition to viewing
information about the route between the venue andnearest station, the user can also refer to information
about nearby wheelchair-friendly facilities such as
multi-functional toilets, information centers, and rest
areas. At the same time, the surrounding walkways
are displayed in three different colors (green, yellow,
and red) in ascending degree of barrier to mobility.
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Feature Articles

AWS
Entire route (transit.2020.ntt)Content DB1
Service user

Cloud Front

LB

Web server 1
Web server 2

S3

Eco-Mo Foundation
segment

Cloud
WAF

Amazon VPCHearing
Content DB2 connection

RakuRaku
Odekake-net

XFARM (Laboratory Cloud)Minna de MaPiece server

Walking map (walkmap.2020.ntt)

Map service(ZENRIN
DataCom)

Firewall

Stationcongestioninformation
estimation server(DOCOMO)

LB

RP

Web/AP server 1

LB

RP

Web/AP server 2FP

DB: database
FP: forward proxy
LB: load balancer

Station-congestioninformationacquisition server

MaPiece DB1
MaPiece DB2
Production system
MaPiece DB
Update system

RP: reverse proxy
WAF: web application firewall

Minna deMaPiececlientFig. 4. Schematic of Japan Walk Guide system (omitting staging environment).

By clicking on a particular walkway, the user then canconfirm its slope and width displayed in conjunction
with photographs of the walkway. If the user wants to
go to a facility that is in the vicinity but off the route
between the venue and nearest station, they can checkthe best route that matches their particular disability
characteristics. The app also has a function thatallows users to correct errors in the barrier-free information. If the user finds an error in the barrier-free
information, they can report it using the “ ” or “×”button and request a volunteer to correct the information (Fig. 3(4)). Thanks to the cooperation of users
and volunteers, it became possible to update theinformation during the service period, thereby creating a more-accurate barrier-free map.
(4) Information about congestion at stations
Wheelchair users find it difficult to move around a
station and board a train when the station is crowded.
As mentioned above, the COVID-19 pandemic has
further strengthened the need to avoid congestion.
For wheelchair users to be able to go out withoutanxiety, we added a function that displays information about expected congestion at the station nearest
the venue so that wheelchair users can avoid congested areas (Fig. 3(5)).
The station-congestion information is provided
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Vol. 20 No. 2 Feb. 2022

through cooperation with railway companies (namely, Tokyo Metro, East Japan Railway, and Tokyo
Waterfront Area Rapid Transit) by linking with station-congestion prediction technology (developed by
NTT DOCOMO), which uses artificial intelligenceand demographic information based on cell-phonebase-station operation information. By modeling therelationship among the estimated number of passengers at a station during past events and the population-distribution data and weather data at that time,
this technology can predict the number of passengers
at a station at 10-minute intervals into the future (forup to 90 minutes) from the most-recent population
distribution, weather, and event-schedule data. The
population-distribution data are estimated using aservice called Mobile Spatial Statistics® Domestic
Population Distribution Statistics (real-time version)[3]. Since this service can obtain past (one hour ago
at latest) population-distribution data, it is possible toreflect the latest congestion situation and predict congestion with high accuracy [4].
2.3 System configuration
The system configuration of Japan Walk Guide isshown in Fig. 4. The app is composed of two units: (i)an entire route unit that provides public-transportation
63

Feature Articles

transfer information and (ii) a walking map unit thatprovides barrier-free information for walking routes.
The transfer information is generated using the application programming interface (API) of RakuRaku
Odekake-net [1]. Due to the security requirements of
RakuRaku Odekake-net, it is necessary to use an
Amazon Virtual Private Cloud (VPC) peering connection, so we built the entire-route unit on an Amazon Web Services (AWS) platform.
The walking routes were provided by combining
the official accessible routes (official routes for people with limited mobility) to the venues described in
the Transportation Plan V2 (published by the Bureauof Olympic and Paralympic Games Tokyo 2020
Preparation of the Tokyo Metropolitan Government)
and barrier-free information collected by the All
Japan Business Committee. The barrier-free information was created using Minna de MaPiece as a base/platform engine and superimposing it on the map
service.
ZENRIN DataCom’s “Itsumo NAVI API/SDK” [5]was used as the map service. The walking-map unit
was built on XFARM, a cloud environment of NTT
laboratories.
3. Barrier-free information and communication
technology MaPiece®
To support people with limited mobility, such as thedisabled and elderly, it is important to prepare barrierfree information for navigation that provides users
with routes that can be taken without fail, in addition
to the development of hardware such as barrier-freefacilities.
In the past, municipalities commissioned experts
with surveying skills to create barrier-free information on the basis of their standards. Due to the highcost of surveying, however, it was difficult to create
and update the survey data frequently. Moreover, thestandards differed from municipality to municipality,
so it was difficult to use data across the board.
To address these issues, MaPiece® was developed
to enable volunteers who do not have map-making
expertise to collect barrier-free information for highly accurate navigation in accordance with the Specification for Spatial Network Model for Pedestrians
formulated by the Ministry of Land, Infrastructure,
Transport and Tourism [6].
To enable sustainable collection and update of barrier-free information, MaPiece ® is configured as
three sub-technologies: (i) Hakatte MaPiece, a fieldsurvey tool for collecting initial information; (ii)
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Vol. 20 No. 2 Feb. 2022

Minna de MaPiece, which collects corrected andupdated information from users when they use theservice and updates the information in a social-networking manner; and (iii) Aruite MaPiece, which
automatically collects road-surface information frompedestrians’ smartphone sensor data by using cloudsensing technology (Fig. 5).
The barrier-free information collected by volunteers using Hakatte MaPiece and Aruite MaPiece isimported for Minna de MaPiece, and through the APIof Minna de MaPiece, the information from users is
retrieved and reflected in the latest posted information. The updated data are compliant with the Specification for Spatial Network Model for Pedestrians
and can be used for other barrier-free information
services even after the Japan Walk Guide service
ends.
4. Results
Table 1 lists the number of users of Japan Walk
Guide from July 13, 2021 to September 5, 2021. In
2021, the international sporting event was held inJapan without spectators, and Japan Walk Guide wasused by volunteer staff with impaired mobility.
Through a questionnaire and interviews, we also
evaluated the experiences of five wheelchair users
during the event. All five respondents answered thatthey would use Japan Walk Guide for finding out how
to get to event sites compared with current guiding
current services. Each user gave a different reason.
Comments such as “road conditions to the venue aredisplayed accurately,” “the train-information function is convenient,” “various barrier information suchas the slope of the walkway is posted,” and “information on wheelchair-accessible toilets is useful” demonstrated the usefulness of providing information via
Japan Walk Guide in conjunction with the abovementioned information on slopes and steps based onstandards provided by the Ministry of Land, Infrastructure, Transport and Tourism in a one-stop manner.
The majority of the respondents felt that the congestion information was necessary; in particular, fourout of five answered that it was “necessary” or “betterto have than not,” indicating that the information was
generally useful. Regarding a comparison of theusage rates by function, the usage rate of stationcongestion information was the highest among theusers who referred to the walking-route guidance
screen (Table 1). However, because the target event
was held without spectators, cases of congestion at64

Feature Articles

Development period: 2016–2017

Developed in 2018

Development period: 2018–2019

Hakatte MaPiece

Minna de MaPiece

Aruite MaPiece

Technology for collecting
accessibility information

Social-networking-typeattribute-information
generation technology

Pedestrian-sensing technology

Can be investigated without
detailed knowledge

Collect information while
using it on a daily basis

Collect road-surface
information by just“walking”

Flat

Road surface(steps, etc.)

Facilities (elevators, toilets, etc.)
and road surfaces (steps, etc.)

Collection
targetSemi-automatic
Extracts updated information
about facilities and roadsurfaces from residents’ posts

ManualSurveyor enters initial
information on tablet

Collection
methodStairs/slope

Automatic
Collects road-surface conditions
over a wide area when moving
along a sidewalk.

Fig. 5. Overview of three technologies comprising MaPiece®.

Table 1. Total number of users during the service-provision period.
(xx%) indicates usage ratio in relation to total number of users
Number of users by function on the walking-route-guidance screen

Total number ofusers

Number of users
referring towalking-route
guidance

Number of users
referring to surrounding
information

Number ofphoto-reference
users

Number of users
referring to roadinformation

Number of users referringto station-congestion
information

1895

982 (51.8%)

128 (6.8%)

94 (5.0%)71 (3.7%)

210 (11.1%)

stations did not occur, so we were unable to evaluate
the actual effect of the station-congestion information.
5. Concluding remarks
Due to the fact that many of the venues were notopen to the public, only those involved in the event
were able to use our service, and the general public
was not able to experience it. Even so, the release ofJapan Walk Guide at a sporting event that drew
worldwide attention to barrier-free initiatives in thedomestic and international press. For example, it wasfeatured in Taiwanese web media as one of ten friendly actions that supported athletes in the “spirit ofinclusion.” We believe that our efforts were significant from two aspects: (i) raising awareness of thefact that ordinary people can collect barrier-free
NTT Technical Review

Vol. 20 No. 2 Feb. 2022

information and create barrier-free maps themselvesand (ii) fostering a culture of continuously updating
barrier-free maps.
The barrier-free information collected by the All
Japan Business Committee will be released as open
data by the Geospatial Information Center (operated
by the Association for Promotion of Infrastructure
Geospatial Information Distribution). We hope thatthe above-described recognition will be an opportunity for the barrier-free information created by thevolunteers to be used in various applications andservices. In the future, we will use our efforts for the
event as a first step to promote research and development of new inclusive services on the basis of theevaluation results through the provision of applications. We will also contribute to the creation of an
inclusive society where people with disabilities canlive independently with peace of mind.
65

Feature Articles

Acknowledgments
We thank the Public Relations Bureau, Transportation Bureau, Technology Services Bureau, and Paralympic Management Office of the Tokyo Organising
Committee of the Olympic and Paralympic Gamesand the Ministry of Land, Infrastructure, Transport
and Tourism for their cooperation and advice in thedevelopment of this application. We also thank the
Barrier-Free Promotion Department of the Foundation for Promoting Personal Mobility and EcologicalTransportation for their coordination of the Raku­
Raku Odekake-net project and the All Japan BusinessCommittee, its participating companies, and volunteers who worked together to collect the barrier-free
information and provide the application.

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Vol. 20 No. 2 Feb. 2022

References
[1]
[2]
[3]
[4]
[5]
[6]

RakuRaku Odekake-net, https://www.ecomo-rakuraku.jp/en
Transportation Plan V2 (in Japanese), https://www.2020games.metro.
tokyo.lg.jp/taikaijyunbi/torikumi/yusou/yusou_v2_koushin/
Mobile Spatial Statistics ® Domestic Population Distribution
Statistics (real-time version) (in Japanese), https://mobaku.jp/service/rt_distribution/
Press release issued by NTT DOCOMO on Aug. 19, 2021 (in Japanese), https://www.nttdocomo.co.jp/binary/pdf/info/news_release/
topics_210819_01.pdf
Itsumo NAVI API/SDK (in Japanese), https://www.zenrin-datacom.
net/solution/api
C. Yamamoto, K. Funakoshi, H. Konishi, K. Ochiai, and A. Kawanobe, “Technology for Social Development of Accessibility Maps,”
NTT Technical Review, Vol. 14, No. 7, July 2016.
https://www.ntt-review.jp/archive/ntttechnical.php?contents=
ntr201607fa5.html

66Feature Articles

Yusuke Ichikawa

Senior Research Engineer, Cyber-World Laboratory, NTT Human Informatics Laboratories.
He received a B.E. and M.E. in measurement
engineering from Keio University, Kanagawa, in
1995 and 1997, and Ph.D. in informatics from
Shizuoka University in 2020. He joined NTT
Multimedia Network Laboratories in 1997. Since
1998, he has been researching and developing
recommendation systems. He is a senior memberof the Information Processing Society of Japan(IPSJ) and received the 2005 and 2019 IPSJ
Yamashita SIG Research Award.

Hirofumi Abe

Senior Research Engineer, Cyber-World Laboratory, NTT Human Informatics Laboratories.
He received a B.E. and M.E. in measurement
engineering from Keio University, Kanagawa, in
1995 and 1997 and joined NTT Network Systems Laboratories in 1997. Since 1998, he has
been researching and developing multimedia
applications, and since 2016, he has been
researching and developing an easily accessible
environment using geographic information systems.

Tatsuaki Ito

Researcher, Cyber-World Laboratory, NTT
Human Informatics Laboratories.
He received a B.E. and M.E. in informationengineering from Shizuoka University in 1993
and 1995 and joined NTT Human Interface
Laboratories in 1995. He has been researchingand developing information systems for medical
and welfare fields. He received the 2017 LOIS
Research Award from the Institute of Electronics,
Information and Communication Engineers(IEICE).

Shunsuke Konagai

Senior Research Engineer, Cyber-World Laboratory, NTT Human Informatics Laboratories.
He received a B.E. in computer science fromThe University of Electro-Communications,Tokyo, in 1991 and joined NTT Human Interface
Laboratories the same year. He has been
researching and developing multi-media communication systems, web search engines, anddigital map systems.

NTT Technical Review

Vol. 20 No. 2 Feb. 2022

Satoshi Sakuma

Senior Research Engineer, Supervisor, CyberWorld Laboratory, NTT Human Informatics
Laboratories.
He received a B.E. and M.E. in engineeringfrom Keio University, Kanagawa, in 1993 and1995 and joined NTT in 1995. His research interests are image processing and object recognition.
He is a member of IEICE.

Satoshi Fukada

Senior Manager, Mobility and Smart City
Business Producer, Strategic Business Creation
Team, Research and Development Planning
Department, NTT.

Shingo Kinoshita

Vice President, Head of NTT Human Informatics Laboratories.
He received a B.E. from Osaka University in1991 and M.Sc. with Distinction in technology
management from University College London,
UK, in 2007. He joined NTT in 1991 and was asenior manager of the R&D planning section of
the NTT holding company from 2012 to 2015.
He is currently a visiting professor at the Art Science Department, Osaka University of Arts, andvisiting executive researcher at Dentsu Lab
Tokyo. He has served as a member of the Japan
Science and Technology Agency (JST) JSTMirai Program Steering Committee, member ofthe All Japan Confederation of Creativity (ACC)TOKYO CREATIVITY AWARDS 2021 Judging
Committee, and member of the Broadband Wireless Forum Steering Committee. He has been
engaged in R&D of a media-processing technology, user interface/user experience, communication protocols, information security, machinelearning, service design, and technology management. Until recently, he had been in charge ofNTT’s Tokyo2020 initiatives, including sportswatching video technology, inclusive design forsocial issues, and promoting the use of ICT in
kabuki, entertainment, and media arts such as live
music.
He has been in his current position since 2021,
where he manages R&D on information andcommunication processing of humans based onhuman-centered principles.

67

Feature Articles: 2021 International Sporting Event and
NTT R&D—Technologies for Making the Event Inclusive

Goalball × Ultra-realistic
Communication Technology Kirari!
Kazu Miyakawa, Takuya Gouda, Yuki Yoshida,
Kimitaka Tsutsumi, Kentaro Shimizu, and Takuya Indo
Abstract

NTT is promoting research and development to enable people with various physical conditions,
including disabilities, to enjoy watching sports. Focusing on goalball, which is a type of parasport, thisarticle introduces a new experience of sports watching that provides a sense of realism as if the spectators
were watching the game at the competition venue. This experience is possible by using ultra-realistic
communication technology called Kirari! (particularly, highly realistic sound-image localization technology) for producing stereophonic sound.
Keywords: sports viewing, ultra-realistic communication, sound-image localization

1. Overview
To create a symbiotic society through sports, we at
NTT laboratories have been researching viewing
methods that allow the visually impaired to enjoy
sports events. The main method for the visually
impaired to watch sports has been through live radio
and television broadcasts. However, verbal explanations cannot effectively convey the details of anaction (for example, the rhythm of a rally or impact ofhitting the ball) or feeling the intensity of play [1].
The visually impaired use sensory information otherthan sight to watch sports. One such example is using
sound. In the system described in this article (called“goalball experienced through sound”), we reproduced the acoustic space of a game of goalball, in
which sound plays a leading role, through 100 speakers (Fig. 1) by using our ultra-realistic communication technology called Kirari!. This system enables
the visually impaired to enjoy watching goalball byfollowing the movement of the ball via sound only.
This provides them with a realistic experience as if
they were on the playing court.

created a spectator area that simulates a full-scale
tournament court and enables visually impaired spectators to experience the acoustics where the players
are located in front of the goal (team area) (Fig. 2).
Two rows of 50 speakers (speaker arrays), one placedin front of and one placed behind the spectator seats,
sequentially synthesize the sound of the ball bouncing and the sound of the players’ movements in amanner that reflects the position of the ball on the

2. Spectating experience
With “goalball experienced through sound,” we
NTT Technical Review

Vol. 20 No. 2 Feb. 2022

Fig. 1. R eproduction of an acoustic space with 100
speakers.

68Feature Articles

18.0 m

9.0 m

Spectator
7.5 m

Spectator area

4.5 m

Speaker array (front)

Speaker array (rear)Fig. 2. Spectator area that simulates a tournament court.

Competition venue +broadcasting station
Systemconfiguration

HD camera
2ch
microphone

Remote venue
Video-display
deviceBroadcastfacility

Broadcastreceiver

Real-time ballinformation
input device

Real-time highly
realistic soundimage-localization
deviceSpeaker array
Speaker array

Fig. 3. Configuration of the entire system.

playing court. This setup allows the spectators to follow the movements of the players and ball by soundalone in such a way that they can experience the powerful sound of the ball as if the ball were flying
towards them.
3. Technology
3.1 H ighly realistic sound-image localization
technology: Kirari!
Kirari! is a communication technology that enables
spectators to experience watching a game as if they
were in the competition venue, even if they are far
from the venue [2]. With “goalball experienced
through sound,” we created an acoustic experience byusing highly realistic sound-image localization technology, one of the technical elements of Kirari!. This
technology reproduces the spatial and physical wavefronts of sound on the basis of a physical model [3].
It separates the sound collected with a single microphone at the tournament venue and reproduces it as if
a specific sound were generated at an arbitrary posiNTT Technical Review

Vol. 20 No. 2 Feb. 2022

tion. A key point of this technology is a group of
speakers (speaker array) closely arranged in a straightline. By adjusting the playback timing and power ofthe sound radiated from each speaker to focus thesound at an arbitrary position, a sound field is reproduced as if a sound source existed there.
The configuration of “goalball experienced throughsound” is shown in Fig. 3. Due to operational constraints, we could not set up our own cameras totransmit the event, so we decided to use broadcast
video. Video images of the game shot at the venue ofa goalball tournament are transmitted to a remote site
as broadcast waves via the broadcasting equipment of
the broadcasting station. At the remote site, the position of the ball and players as well as the information
about the type of ball thrown (acquired from thereceived broadcast-wave images) are input in realtime, and an acoustic space is created on the basis ofthat spatio-temporal information (Fig. 4).
We aimed to extract the locations of the ball andplayers, as well as information about the type of ballthrown, from the broadcast video. However, the69

Feature Articles

Watching live video of the game

Inputting ball position,etc. in real time

Experiencing live gameswith sound at a remote venue

Fig. 4. Real-time acoustic-space reproduction.

Team A
Start throwing
ball

Reset

With
run-upWith
run-upWith
run-upNo
run-upNo
run-upNo
run-upGroundingthe ballBouncing
the ballDefenseDefense

Send

DefenseTeam B

Fig. 5. Real-time input UI for ball-throwing information.

cameras and angle of view change frequently during
broadcast video, so we adopted a user interface (UI)
through which the ball position is input manually(Fig. 5). Two people, one in charge of team A and one
in charge of B, each used a tablet with the UI installed
to watch the broadcast video and enter the starting
position and time of each team’s attack, type of throw(bouncing ball or ball along the ground), and resultof the throw (blocked, goal, or out of bounds) with thepush of a button. From the input result, sound information is generated from a sound-source file of thethrowing sound prepared in advance. That information is then processed using Kirari! via the network to
reproduce the ball-throwing situation in real time.
3.2 Acoustic production with inclusive design(1) Selecting sounds to localize as the sound image
To reproduce the acoustic space that the players
hear on the court and allow non-players to fully experience the players’ excellent sense of hearing, weused an inclusive design method, which involved
NTT Technical Review

Vol. 20 No. 2 Feb. 2022

goalball players and the visually impaired in the
upstream design process. Specifically, we definedand created the requirements for the sound through aprocess of interviews, observation of ball-throwing
situations, and acoustic evaluation (Fig. 6). This process enabled us to understand the various sounds
heard on the goalball court, but distracting sounds
made by the opposing team (such as the sounds madeto obscure the throwing position by hitting the floor)
were included but are ignored by the players. In otherwords, the players always search for the ball by following a series of throwing sounds such as the run-up
sound of the player holding the ball and that of theball hitting the floor in the manner of a single stroke.
Accordingly, we decided to focus on the throwing
sounds (run-up sound, ball sound, and result sound ofball throwing such as blocked shot or goal) and reproduce those sounds. That is to say, instead of trying to
reproduce the acoustic space of the physical tournament venue as is, we attempted to reproduce thesounds that the players selectively perceive from the70

Feature Articles

Fig. 6. Players experiencing “goalball experienced throughsound”.

various sounds that they hear. By doing so, we aimed
to allow non-players to experience the simulated
exceptional auditory sense of the players.
(2) Simplification of sound-image localization
For the path of the thrown ball, the players distinguish the distance from one end of the goal to theother (9 m) in nine segments (each with width of 1m). However, the spatial resolution of sound of nonplayers is not as good as that of players, so it is difficult for non-players to determine the route of thethrown ball when the sound image is localized as is.
By reducing the spatial resolution in the goal direction from nine segments to three (left, center, andright), we improved the non-players’ recognition rateof the ball position by sound.
We also created an introductory content to give alecture on sound localization to the non-playing spectators so they could get used to sound localization. In
preparation for experiencing a game, the sound ofthrowing the ball along various paths was localized.
Non-players commented that they could gradually
determine the path of the thrown ball just by listening
to the sound. This suggests that listening the introductory content before the game was useful to understand the game. Therefore, by simplifying the path of
the thrown ball and creating the introductory content,
we were able to create a system that allows nonplayers to experience the sounds that the players hear
during a game.
4. Results
Initially, “goalball experienced through sound” wassupposed to be a spectator event at the international
sporting event in 2021 for people with disabilities,
but the event was cancelled to prevent the spread of
COVID-19 infections. However, during a hands-on
evaluation of the experience to prepare the actual
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Vol. 20 No. 2 Feb. 2022

event, we received high evaluations from non-playerswith visual impairments.
The evaluation was based on three questions: “Canyou understand the state of the play,” “Can you feelthe texture of the goalball-like sound,” and “Can you
feel the power of a ball and realism.” In response tothese questions, the evaluators commented, “Thesound texture is realistic. Reproduction of the soundof the ball going back and forth is excellent. It’s likea real game!”, “Unlike listening to television, I could
see where the ball was coming from and going to,”and “In a stadium, you hear the sound from outside
the court, but this system gave me a more realistic
feeling as if I was inside the court.”
We also received comments such as, “It would beeasier to follow the path of the ball if we could also
hear the sound of the players moving with the ball”
and “It would be better if we could hear the players
talking so we could understand their strategies.” In
general, by focusing on the goalball-like sound players hear through the inclusive design method mentioned above, we were able to create an acoustic system that enables non-players to understand the stateof play of a goalball game.
5. Concluding remarks
We developed a system called “goalball experienced through sound,” which allows people to enjoy
goalball through only sound and evaluated it in a
hands-on manner with real spectators (including
those with visual impairments). Initially, we planned
to reproduce the sound of the ball moving on the
court by using Kirari!; however, from the results ofthe evaluation, we realized that not only the sound of
the ball moving but also the sound of the players’
movements and the connection of a series of sounds
are important in creating the spectator experience.
Although the spectator event at which we wereplanning to provide this technology was cancelled
due to the COVID-19 pandemic, we plan to enable
many people to experience the results of “goalballexperienced through sound” in conjunction withgoalball tournaments and efforts to promote parasports. We will also continue our research and development from an inclusive perspective that allows
people with various physical conditions to learn thevalue of information and communication technology.
Acknowledgments
The authors thank Akiko Adachi (Leifras Co., Ltd.),
71

Feature Articles

the players, and visually impaired participants who
cooperated with the acoustic evaluation, the teachersof Yokohama City and Yokohama Municipal Special
Needs School for the Blind, the Japan Goalball Association, and the Japanese Para Sports Association for
their comments and cooperation in the design of the“goalball experienced through sound” experience.

Kazu Miyakawa

Senior Research Engineer, NTT Human Informatics Laboratories.
He joined NTT in 1998, and is engaged inresearch of media processing and Kirari!.

Takuya Gouda

Research Engineer, NTT Human Informatics
Laboratories.
He joined NTT DATA in 2009 and has been
engaged in system development for the financial
industry. He was in charge of using NTT’s communication technology for the 2021 international
sporting event in Tokyo.

References
[1]

[2]
[3]

A. Hayashi, A. Ito, and J. Watanabe, “Sports Social View: A Generative Sports Viewing Method that Physically Translates the Game andShares It with the Visually Impaired,” Transactions of the Virtual
Reality Society of Japan, Vol. 25, No. 3, pp. 216–227, 2020.
Kirari!, https://group.ntt/en/magazine/blog/kirari/
K. Tsutsumi and H. Takada, “Powerful Sound Effects at Audience
Seats by Wave Field Synthesis,” NTT Technical Review, Vol. 15, No.
12, 2017.
https://www.ntt-review.jp/archive/ntttechnical.php?contents=
ntr201712fa5.html

Kimitaka Tsutsumi

Senior Research Engineer, Natural Communication Project, NTT Human Informatics Laboratories.
He received a B.E. and M.E. in informatics
from Kyoto University in 2004, 2006, and Ph.D.
from The University of Electro-Communications, Tokyo, in 2020. He joined NTT CyberSpace Laboratories (now, NTT Media Intelligence Laboratories) in 2006. He has participatedin standardization efforts in International Telecommunication Union Telecommunication
Standardization Sector (ITU-T). He joined NTT
DOCOMO Research Laboratories in 2010,
where he was involved in standardization activities of 3GPP (3rd Generation Partnership Project) on enhanced voice services. He has beenwith NTT Human Informatics Laboratories since2015. His current research interests include
speech coding and signal processing for spatial
reproduction. He received the Technical Development Award from the Acoustical Society ofJapan (ASJ) in 2016. He is a member of ASJ, the
Audio Engineering Society, and the Institute ofElectrical and Electronics Engineers (IEEE).

Kentaro Shimizu

Yuki Yoshida

Research Engineer, NTT Human Informatics
Laboratories.
She received a B.Sc. and M.Sc. from the University of Tsukuba. She joined NTT and engaged
in research and development of human interfaces. In 2019, she joined the 2020 Epoc-Making
Project, where she has been engaged in service
promotion to celebrate Tokyo 2020.

Senior Research Engineer, Supervisor, NTT
Human Informatics Laboratories.
He received an M.S. in electronics and information engineering from Yokohama National
University, Kanagawa, in 1999 and Ph.D. inmedical research from Tokyo Women’s Medical
University in 2009. He joined NTT in 1999. He
is a member of the Institute of Electronics, Information and Communication Engineers (IEICE),
the Information Processing Society of Japan(IPSJ), the Japanese Society for Artificial Intelligence, the Japan Society for Health Management, and the Japan Society of Computer Aided
Surgery.

Takuya Indo

Senior Research Engineer, Supervisor, NTT
Human Informatics Laboratories.
He received a B.S. in physics from Kyoto University in 1993 and joined NTT the same year.
His research interests include media processing
and human-computer interaction. He is a member of IPSJ and the Association for Computing
Machinery (ACM).

NTT Technical Review

Vol. 20 No. 2 Feb. 2022

72

Global Standardization Activities

Recent Activities of ITU-R Study
Group 5 on Terrestrial
Radiocommunication Systems
Shinya Otsuki, Junichi Iwatani, and Nobuki Sakamoto
Abstract

Radiocommunication systems, such as mobile communication systems, which are represented bysmartphones, wireless local area network systems, which are commonly used at home and office, andfixed wireless systems, which provide flexible and resilient communication in times of disasters, play
important roles in telecommunication networks. The International Telecommunication Union - Radiocommunication Sector (ITU-R), an international standardization organization, is responsible for standardization of radiocommunication systems and the frequencies they use. Recent activities of the ITUR’s Study Group 5 and its Working Parties, which deal with terrestrial radiocommunication systems, andthe contributions of NTT laboratories and NTT DOCOMO to those activities, are outlined in this article.
Keywords: ITU-R, wireless LAN, IMT

1. Structure of ITU-R and jurisdiction of
Study Group 5
The International Telecommunication Union Radiocommunication Sector (ITU-R) is a sector of
the ITU responsible for establishing regulations andstandards for radiocommunication systems. The
structure of ITU-R is illustrated in Fig. 1. The Study
Groups (SGs) work on developing technical, operational, and procedural bases for efficient use of theradio spectrum and the geostationary-satellite orbit
and develop ITU-R Recommendations and Reports.
One of the missions of SGs is to conduct researchnecessary for discussions at the World Radiocommunication Conference (WRC), which revises the Radio
Regulations (RR) providing international rules andregulations for spectrum allocation to radio services,use of satellite orbits, and administrative and operational procedures for radio stations, all of which areneeded for the use of radio waves. Six SGs have been
established at the ITU-R, and their compositions areshown in Table 1 [1].
As shown in the table, SG 5 is in charge of systems
and networks for fixed, mobile, radiodetermination,
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Vol. 20 No. 2 Feb. 2022

amateur, and amateur-satellite services, and Dr.
Hiroyuki Atarashi (NTT DOCOMO) from Japan was
appointed as the vice chair for the current study cycle(2019–2023) as well as the previous study cycle(2015–2019). Under SG 5, there are four Working
Parties (WPs), as shown in Table 2, and these WPs
conduct discussions on ITU-R Recommendations. As
delegations of part of Japan led by an official of the
Ministry of Internal Affairs and Communications,
NTT laboratories have been participating in WP 5A,
which is in charge of land mobile services excludingInternational Mobile Telecommunications (IMT)*1,
and WP 5C, which is in charge of fixed services. NTT
DOCOMO has been participating in WP 5D, which isin charge of IMT.

*1 IMT: Includes 3rd-generation mobile communication systems
and beyond, such as IMT-2000, IMT-Advanced, and IMT-2020
systems. IMT-2000 includes W-CDMA (Wideband Code Division Multiple Access), HSPA (High-Speed Packet Access), andLTE (Long Term Evolution) as radio interfaces. IMT-Advanced
includes LTE-Advanced as a radio interface.

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Global Standardization Activities

World Radiocommunication
Conference (WRC)
Revises the Radio Regulations

Radiocommunication
Assembly (RA)Radio Regulations Board(RRB)

Approves Resolutions andRecommendations

Study Groups (SGs)
Carry out studies

Approves procedural rules andresolves disputes

Conference
Preparatory Meeting(CPM)

Radiocommunication
Advisory Group (RAG)
Submits advice to thedirectorMakes WRC preparations

Director
Radiocommunication
BureauFig. 1. Structure of ITU-R.

Table 1. Structure of ITU-R SGs.
Scope of work
SG 1: Spectrum management

Spectrum management principles and techniques, general principles of sharing, and spectrum monitoring

SG 3: Radiowave propagation

Propagation of radio waves in ionized and non-ionized media, and the characteristics of radio noise

SG 4: Satellite services

Systems and networks for fixed-satellite, mobile-satellite, broadcasting-satellite, andradiodetermination-satellite services

SG 5: Terrestrial services

Systems and networks for fixed, mobile, radiodetermination, amateur, and amateur-satellite services

SG 6: Broadcasting service

Radiocommunication broadcasting, including vision, sound, multimedia, and data services principallyintended for delivery to the general public

SG 7: Science services

Systems for space operation, space research, earth exploration and meteorology; systems for remotesensing, including passive and active sensing systems; radio astronomy; and standard frequency andtime signals

Table 2. Structure of WPs in SG 5.

2. Recent status of SG 5-related meetings

Scope of work

2.1 WP 5A
WP 5A is mainly responsible for land mobile services (excluding IMT). Wireless access systems
including wireless local area networks (LANs), public protection and disaster relief wireless systems,
railway wireless systems, intelligent transport systems (ITS), amateur radio, and new technologies forland mobile services in general are being discussed as
the main target systems, and Recommendations andReports are being developed. In this section, the status of discussions at WP 5A, focusing on the topic of
NTT Technical Review

Vol. 20 No. 2 Feb. 2022

WP 5A

Land mobile service above 30 MHz (excluding IMT);
wireless access in fixed services; amateur andamateur-satellite services

WP 5B

Maritime mobile service including Global Maritime
Distress and Safety System (GMDSS); aeronauticalmobile service; and radiodetermination service

WP 5C

Fixed wireless systems; HF and other systems below
30 MHz in fixed and land mobile services

WP 5D

IMT Systems

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Global Standardization Activities

5925 MHz 5945 MHz
Frequency band

6425 MHzThe Radio
Regulations(International)

Fixed, Satellite

Wireless LAN use(National
regulations)

7075 MHz 7125 MHz

Fixed“Mobile”
USA, South Korea, etc.
UK
EU

Fig. 2. International regulations regarding the use of the 6-GHz band of wireless LANs and domestic services of several
countries.

wireless LANs, which is strongly related to the NTT
Group’s business, is explained.
2.1.1 Discussions on wireless LANs
At the 2019 World Radiocommunication Conference (WRC-19), the revision of the RR [2] wasagreed to ease the restrictions on 5-GHz-band wireless LANs that allows outdoor use and higher transmission power in the 5.2-GHz band. Since WRC-19,
discussions on wireless LANs have continued, andthe revision of ITU-R Recommendations M.1450 and
M.1801, which contain technical guidelines for wireless LANs, are being discussed. Two points for therevision are under discussion. The first is that Recommendation M.1450 includes the conditions of wireless LANs described in the RR and the national regulations of major countries; however, it does not reflect
the latest modification of them, and its current version is being discussed for revision. Japan proposed
to revise the texts on the basis of the recent revisionsof the RR that include relaxed conditions for the 5.2GHz band decided at WRC-19 and relevant national
regulations in Japan, which were reflected in theworking document for the revision of the Recommendation. It is expected that the Recommendation will
be discussed further for revision. The second point of
discussion is revision of the Recommendations on thebasis of the recent status of wireless LANs including
updates to the Institute of Electrical and Electronics
Engineers (IEEE) 802.11 standard. IEEE is proposing to update the summary section of the wireless
LAN standards in Recommendations M.1450 and
M.1801 to reflect the extension of the frequency band
specified in IEEE 802.11ax that uses the 6-GHz band.
Although this proposal is supported by the US, theUK, and other countries, China and Russia do notsupport it because they are concerned about interferNTT Technical Review

Vol. 20 No. 2 Feb. 2022

ence with fixed satellites that may be caused byincreased use of wireless LANs in the 6-GHz band.
With regard to the frequency allocation in the RR, as
shown in Fig. 2, the 6-GHz band is allocated to multiple services (such as fixed satellite services andother fixed services) in addition to mobile services
such as wireless LANs and IMT. In several countries,
wireless LANs are used in the 6-GHz band. The useof the 6-GHz band for wireless LANs is also being
discussed in Japan.
2.1.2 Discussions on other systems
With regard to railway wireless systems, developing a new ITU-R Recommendation for global orregional harmonization of radio frequency between
trains and trackside is being discussed. In regard to
ITS, the preparation of an ITU-R Report that clarifies
the requirements for wireless communications forconnected automated vehicles, which are expected tobe put into practical use in the future, is being discussed. Regarding the terahertz band (275 to 450GHz), which is expected to be used for future sixthgeneration mobile communication systems (6G),
technologies for the coexistence of multiple different
systems are being discussed.
2.2 WP 5B
The scope of WP 5B is the maritime mobile service,aeronautical mobile service, and radiodetermination
service (e.g., radar), and this WP deals with many
topics discussed at WRCs such as unmanned aircraft
systems and sub-orbital vehicle communication systems. Although telecom operators have made few
contributions to this WP, the NTT Group addresses
these topics via liaison statements from other WPs
that reflect the Group’s opinions.

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Global Standardization Activities

Table 3. WRC-23 Agenda Item 1.2: Candidate frequency bands for additional identification for IMT.
Frequency band

Region 1(Europe, Russia, Arabcountries, Africa)

Region 2(North and SouthAmerica)

Region 3(Asia-Pacific region)

3300–3400 MHz

Subject of study

Subject of study–

3600–3800 MHz–

Subject of study–6425–7025 MHz

Subject of study––7025–7125 MHz

Subject of study

Subject of study

Subject of study

10,000–10,500 MHz–

Subject of study–

2.3 WP 5C
The scope of WP 5C is mainly fixed wireless systems (FWSs). This WP is developing ITU-R Recommendations and Reports on transport/trunking wireless network systems, fixed wireless access systems,
mobile backhaul for land mobile radiocommunication, electronic news-gathering systems in the fixed
service, and systems for temporary use in disaster
relief.
One of the discussions in WP 5C is on the use of thehigh-frequency band above 92 GHz, which is expected to be used for communication systems in accordance with recent technical developments. Radiofrequency channel arrangements for FWSs (between
92 and 174.8 GHz) and the technical conditions toprotect the Earth-exploration satellite service (EESS)
are being studied. As a result of WRC-19, the 275-to450-GHz band discussed at WRC-19 is now available
for FWSs, and technologies for protecting EESS thatare required for some of these frequency bands arebeing evaluated and studied. The completion of thesestudies is expected to facilitate high-capacity FWSs
for the mobile backhaul and fronthaul in mobile networks. In addition, WP 5C has completed a revision
work on Recommendations relating to parameters for
FWSs for ultra-high-definition-television signaltransmission used for broadcast auxiliary services.
2.4 WP 5D
At the ITU, cell-phone systems are collectively
referred to as IMT, and WP 5D is responsible for this.
WP 5D is responsible for developing Recommendations and Reports on the IMT radio interface, futuretechnologies and concepts (vision) of IMT, usage of
frequency bands identified for IMT (radio frequency
arrangement), and frequency-sharing studies between
IMT and other services. The standards for fifth-generation mobile communication systems (5G) arecalled IMT-2020*2 in ITU-R, and the first version of
Recommendation ITU-R M.2150, “Detailed specifiNTT Technical Review

Vol. 20 No. 2 Feb. 2022

cations of the terrestrial radio interfaces of International Mobile Telecommunications-2020 (IMT2020)” was published in February 2021. After publication of this Recommendation, development of an
ITU-R Report on the trends regarding future technologies of IMT has started and aiming for completion in 2022. This ITU-R Report contains a compilation of technologies that can be applied to IMT in the
future. Development of an ITU-R Recommendationon the future IMT vision for 2030 and beyond has
also started and is scheduled for completion in 2023.
This Recommendation is aimed to serve as a guidefor the further development of IMT and will includeuse-case scenarios, required capabilities, and a specific development schedule for IMT in the 2030s.
In preparation for WRC-23, studies on utilizationof frequencies for IMT are proceeding at full speed.
In WRC-23 Agenda Item 1.2, which covers identification of additional frequencies for IMT, the frequencies listed in Table 3 are considered for each region.
In Region 3 (Asia-Pacific region), including Japan,
100-MHz bandwidth from 7025 to 7125 MHz isunder consideration. At WRC-19, it was decided to
identify additional frequencies above the millimeterwave band for IMT [3], and at WRC-23, the frequencies to be considered are being selected in the expectation that the demand for IMT frequencies below the
millimeter-wave band will increase in the future.
WRC-23 Agenda Item 1.4 discusses issues concerning the use of frequencies for high-altitude platform stations (HAPS) as IMT base stations (HIBS).
As of 2021, as shown in Fig. 3(a), 1885 to 1980 MHz,2010 to 2025 MHz, and 2110 to 2170 MHz are available
as HIBS frequencies in Region 3, including Japan. In
addition to considering those frequencies, WRC-23
Agenda Item 1.4 considers further identifications of
the frequencies used by HIBS in terms of several*2 IMT-2020: The 3rd Generation Partnership Project (3GPP) 5GSRIT and 3GPP 5G-RIT are included as radio interfaces.

76

Global Standardization Activities

Region 1: Europe, Russian Federation, Arab countries, Africa
Region 2: North and South America
Region 3: Asia PacificUE  HIBS direction
only

Only in Regions 1
and 3

Frequency (MHz)1885 1980

2110

2010

2025

2170
2160

(a) Current HIBS frequencies

In Region 3, UE HIBS
direction only

In Region 3, UE HIBS
direction only

Regions 1 and 2 only

Frequency (MHz)
694

960

1710

1815

1885

2500 2535

2655

2690

(b) Frequency candidates for WRC-23 Agenda Item 1.4
UE: user equipment

Fig. 3. Frequencies for HIBS.

candidate frequencies below 2.7 GHz, as shown in
Fig. 3(b).
WP 5D is conducting preliminary technical studies
to determine (i) whether these candidate frequencies
will harmfully interfere with other wireless systems ifthey are used for IMT or HIBS and (ii) what conditions are necessary to avoid such interference.
Experts on other wireless systems, such as satellite
systems, are also participating in detailed discussions
as well as experts on IMT. On the basis of the resultsof these studies, WRC-23 will make the final decisions on whether to identify additional frequencies
for IMT (Agenda Item 1.2), and whether to identify
additional frequencies for HIBS (Agenda Item 1.4).

future deployment of 5G and Beyond 5G, such as 5G
Evolution and 6G [4], are important from the viewpoint of Japan as a whole. Regarding discussions
other than the WRC-23 agenda, for example, discussions on a wireless LAN, which is an important
access method along with 5G, will have a significant
impact on future wireless access. As the demand forthe wireless spectrum is increasing yearly, in addition
to the above discussions, various discussions on awider range of frequency bands are expected. We
would therefore like to continue to promote ITU-R
activities with an awareness of international coexistence.
References

3. Future prospects[1]

The year 2022 is important in regard to studies forthe 2023 Radiocommunication Assembly (RA-23)
and WRC-23 to be held in 2023. The draft texts fordiscussions at the Second Session of the 2023 Conference Preparatory Meeting (CPM*323-2), which isthe preparatory meeting for WRC-23, will be completed in 2022.
Among the agenda items at WRC-23, such as additional identification for IMT, some discussions on the
NTT Technical Review

Vol. 20 No. 2 Feb. 2022

[2]

A. Hashimoto, “International Standardization of Wireless Communications,” Japan ITU Association, Sept. 2014 (in Japanese).
J. Iwatani, S. Otsuki, Y. Asai, and H. Imanaka, “Activities to Revise
the Radio Regulations on 5-GHz-band Wireless LANs at WRC-19
and ITU-R,” NTT Technical Review, Vol. 18, No. 6, pp. 51–57, June

*3 CPM: Preparatory meeting for the WRC. The 1st session of the
CPM is usually held immediately after the previous WRC, andthe 2nd session of the CPM is usually held about six months before the WRC. At the 2nd session of the CPM, the CPM Reportwill be prepared. The CPM Report is submitted to the WRC andcontains technical studies, solutions based on the studies, and examples of RR revisions.

77

Global Standardization Activities

[3]

2020.
https://www.ntt-review.jp/archive/ntttechnical.php?contents=
ntr202006gls.html
Y. Ito, N. Sakamoto, and H. Shin, “2019 ITU Radiocommunication
Assembly 2019 (RA-19), World Radiocommunication Conference

Shinya Otsuki

Senior Research Engineer, Wireless Access
Systems Project, NTT Access Network Service
Systems Laboratories.
He received a B.E., M.E., and Ph.D. in communication engineering from Osaka University
in 1993, 1995, and 1997. He joined NTT in 1997.
From 1997 to 2008, he studied wireless accesssystems, wireless LAN systems, and wirelesssystems for Internet services in trains. From 2008
to 2011, he was involved in international standardization efforts in evolved packet core andservices using Internet Protocol multimedia subsystems at NTT Service Integration Laboratories. He has been with NTT Access Network
Service Systems Laboratories since 2011 andbeen contributing to the activities of Working
Parties 5A and 5C in Study Group 5 of ITURadiocommunication Sector. He received the
ITU-AJ International Activity Encouragement
Award from the ITU Association of Japan in
2014. He is a member of IEEE and the Instituteof Electronics, Information and Communication
Engineers (IEICE).

[4](WRC-19) Report,” NTT DOCOMO Technical Journal, Vol. 22, No.
1, pp. 45–51, July 2020.
DOCOMO 6G White Paper,https://www.nttdocomo.co.jp/english/corporate/technology/
whitepaper_6g/

Nobuki Sakamoto

Manager, Spectrum Planning Office, NTT
DOCOMO, INC.
He received a B.E. and M.E. from the University of Tokyo in 1998 and 2000 and joined NTT
DOCOMO in 2000. He is currently responsible
for spectrum planning and coordination issues
for IMT systems and ITU-R activities.

Junichi Iwatani

Research Engineer, Wireless Access Systems
Project, NTT Access Network Service Systems
Laboratories.
He received a B.E. and M.E. in electronics
engineering from the University of Tokyo in
1994 and 1996. Since joining NTT Wireless
Systems Laboratories in 1996, he has been
engaged in R&D of wireless access systems.
From 2006 to 2008, he researched the NextGeneration Network in NTT Service Integration
Laboratories. In 2010, he joined NTT Communications, where he was involved in developing
global network services. Since 2013, he has beenwith NTT Access Network Service Systems
Laboratories, where he has been engaged inresearch and standardization of wireless LAN
systems. From 2017 to 2019, he was involved in
activities to revise the Radio Regulations of
5-GHz-band wireless LAN systems for WRC-19
at ITU-R meetings. He received the ITU-AJ
Encouragement Award from the ITU Associationof Japan in 2018. He is a member of IEICE.

NTT Technical Review

Vol. 20 No. 2 Feb. 2022

78

Practical Field Information about
Telecommunication Technologies
Practical Field Information about Telecommunication Technologies

Impact of Wildlife on Access Network
Facilities—Problems Caused by
Monkeys and Countermeasuresagainst Them
Technical Assistance and Support Center, NTT EAST
Abstract

Telecommunication network facilities are exposed to a variety of indoor and outdoor environments inwhich they can be affected by the activities of wildlife. This article introduces problems caused by monkeys on access network facilities and countermeasures against these problems. This is the sixty-eighth
article in a series on telecommunication technologies.
Keywords: aerial cable, cosine curve hanger (CCH), monkey

1. Introduction
Telecommunication network facilities are exposed
to a variety of indoor and outdoor environments inwhich they can be affected by the activities of wildlife. Various problems caused by wildlife on accessnetwork facilities (such as telecommunication cables)
have been reported (Fig. 1). Technical Assistance andSupport Center (TASC) has investigated the problems caused by wildlife on telecommunication network facilities and has taken countermeasures against
these problems [1]. In this article, we focus on the
problems caused by monkeys and our countermeasures against these problems.
2. Problems caused by monkeys regarding
telecommunication network facilities andcountermeasures against themCases of monkeys entering residential areas havebecome more common due to factors such as the
depopulation of villages [2]. Consequently, monkeys
NTT Technical Review

Vol. 20 No. 2 Feb. 2022

have directly affected telecommunication network
facilities, and through behavior such as crossing aerial cables, they have also affected the lives of residents in the neighborhood. Two such cases and thecountermeasures taken are introduced in the following sections.
2.1 D irect impact on NTT’s telecommunication
network facilities
2.1.1 Background
Along an aerial cable route crossing a national
highway, a sagging optical fiber cable was broken bya passing vehicle snagging it (Fig. 2). At the initial
deployment, this aerial optical-fiber cable was bundled together with other cables by using a cosine
curve hanger (CCH). However, from the footage
captured from the dashcam of the vehicle involved in
the incident, it was clear that the cable in question
was unbundled from the CCH even though othercables remained bundled at the time of contact withthe vehicle.

79Practical Field Information about Telecommunication Technologies

A: Birds
B: Rodents
C: Insects
D: Other
wildlife

A: Woodpeckers
C: Swift-moth(Hepialidae spp., esp.
Endoclita excrescens)
larva
C: Ants

A: Woodpeckers
B: Squirrels, Japanese
giant flying squirrels, mice
C: Swift-moth (Hepialidae
spp., esp. Endoclita
excrescens) larva
D: Monkeys

B: Mice
C: Termites

C: Cockroaches
A: Crows
C: Black
cicadasNTT’s telecommunicationbuilding

Underground cables
Underground section

Aerial section

Drop-cablesectionCustomerpremisesFig. 1. Impact of wildlife on telecommunication network facilities.

Aerial opticalfiber cable

Vehicletravelling
direction

Fig. 2. Sagging cable.

Fig. 3. Monkeys crossing cables.

2.1.2 Investigation and analysis of the cause
To investigate the cause of the problem, we set up a
fixed-point camera at the site to monitor the cablestatus for approximately a month. From the captured
video, we observed more than a dozen monkeys per
day crossing the cable in the incident section.
Although the monkeys did not deliberately unbundle
the cable, they strongly grabbed the cable for runningand sometimes pulled the cable when losing their balance (Fig. 3).
After observing the monkeys’ actions, we conducted an experiment to verify the possibility that the
behavior of the monkeys caused the sagging of thecable. At an experimental site, we deployed opticalcables bundled using a CCH, as shown in (1) in
Fig. 4, and locally applied a pulling force to a part ofthe cable (Fig. 4(2)) to simulate a monkey applying apulling (down) force on a cable at that part. When thelocally applied pulling force was gradually increased
and reached about 3 kg, the cable was unbundledfrom the CCH (Fig. 4(3)) and sagged (Fig. 4(4)). The
monkeys captured on video were Japanese macaques,
which were estimated to weigh about 7 to 15 kg. We
therefore considered that they were capable of applying a force exceeding 3 kg when they pulled thecable. There was also no occurrence of severe weather conditions or natural disasters, such as typhoons or
heavy rainfall, that could have caused the cable to sag
before the incident; therefore, we determined that thesagging of the cable was due to the behavior of monkeys crossing the cable.

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80

Practical Field Information about Telecommunication Technologies(1)

Cable position
under normal
conditions(2)

Tensiongauge(3)

Cable is unbundledfrom CCH

Cable ispulled(4)

Cable ispulled in thisdirection

Cable issagging

Fig. 4. How a cable sags.

Secure with tying band

Reinforce with quick holder(a) Securing a cable(b) Reinforcing SH

Fig. 5. Countermeasures against cables sagging.

2.1.3 Countermeasures
We took the following countermeasures to preventthe cable from sagging due to the above-describedbehavior of monkeys.
(1)	The CCH was replaced with a spiral hanger(SH), which is mainly used in high-windareas, and the cable was secured to the suspension wire with tying bands (Fig. 5(a)).
(2)	To prevent the SH from falling, “quick holders,” which are fixtures that prevent damage tothe connectors of the SH and stop them from
dislodging, were installed (Fig. 5(b)).
After these countermeasures were implemented,
cable sagging did not recur. We thus believe thatsimilar countermeasures will be effective at otherlocations in similar environments.
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2.2 E
 xample of impact on the neighboring community
2.2.1 Background
In an area, a large number of monkeys were seencrossing telecommunication cables and became a hot
topic of conversation on social networking services.
Neighboring residents requested that the monkeys be
prevented from crossing NTT’s telecommunication
cables because they were invading nearby fields anddestroying crops. From the results of interviews witha person monitoring monkeys commissioned by local
governments, we learned that the monkeys formedgroups of about 40 and traversed the cables daily insearch of food.
2.2.2 Countermeasures
Since the above problem was already affecting the81Practical Field Information about Telecommunication Technologies

Fig. 6. Bird-damage-prevention device

4m

Utility-poleside

Anti-slip rubber

Fig. 7. Appearance of countermeasure device.

lives of nearby residents and immediate countermeasures were needed, we examined countermeasuresusing currently available products. From the perspective of biodiversity protection, we focused on devising a countermeasure that would not significantly
affect the behavior of the monkeys but would prevent
them invading the living areas of nearby residents bytraversing the cables.
We devised a countermeasure using a commerciallyavailable bird-damage-prevention device to make itharder for monkeys to cross the cable (Fig. 6). This
device has a spiked surface for preventing birds fromperching on cables, and when attached to the cable, it
rotates and makes it difficult for a monkey to grab thecable.
We installed the device on an optical fiber cable
deployed in high monkey traffic area. Initially, thedevice was effective in preventing monkeys fromcrossing the cable. However, we found that monkeys
have very high motor skills, i.e., can leap two to threemeters horizontally and have an excellent sense ofbalance, so they can easily avoid the device and crossthe cable, even from a precarious position. After
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repeated trials while studying the structure and installation method of the device, we determined that thefollowing installation method to be effective (Fig. 7).
(1)	To make the countermeasure device rotate
more easily (i.e., more unstable), cut thedevice into two pieces of 250 mm in length(half the original length) and install the pieces.
(2)	To stop the monkeys jumping over the device,attach multiple pieces (16 in total) with a total
length of 4 m to the cable.
After adopting this installation method, we confirmed that any monkeys that tried crossing the section of the cable in question gave up and turned back(Fig. 8).
3. Concluding remarks
Examples of problems with telecommunication
network facilities caused by monkeys and countermeasures against them were introduced. The surrounding environments of telecommunication network facilities vary considerably, and even if the
problem is the same at each site (in this example,
82

Practical Field Information about Telecommunication Technologies(a) Monkey places its hand on
the countermeasure device(b) The device spins(c) The monkey turns backand runs away

Fig. 8. A monkey trying to cross the countermeasure device, failing, and turning back.

monkeys crossing telecommunication cables), it isnecessary to consider countermeasures that areappropriate for each site.
TASC, including its predecessor, the TechnicalCooperation Department, has been supporting thefield through technical cooperation activities formore than 50 years. Using the knowledge and experience accumulated to date, as well as new technologies, we will continue our efforts to improve thereliability of telecommunication network facilities

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and reduce failures.
References[1][2]“Case Studies on Biological Damage to Telecommunication AccessFacilities and Countermeasures,” NTT Technical Journal, Vol. 27, No.
10, pp. 67–70, 2015 (in Japanese).
Y. Muroyama, “How to Get Along with Monkeys in the Village: Damage Control Concerning Wild Animals,” Kyoto University Press, 2003
(in Japanese).

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Report on NTT R&D Forum—
Road to IOWN 2021
NTT R&D Forum Office
Abstract

NTT R&D Forum—Road to IOWN 2021 was held online over a four-day period from November 16th
to 19th, 2021. This article is an introductory overview of the Forum.
Keywords: R&D forum, IOWN, technical seminar

1. Forum overview
The NTT R&D Forum introduces the latest efforts
by NTT laboratories every year. This year, 97 exhibits
were held in six categories based on the concept of“Road to IOWN 2021,” and 10 lectures/seminars
were streamed as an accessible introduction to thepresent status of the Innovative Optical and Wireless
Network (IOWN) initiative in which the NTT Group
as a whole is engaged.
2. Keynote speeches/special sessions
2.1 Keynote Speech 1
Jun Sawada, President and CEO of NTT, spoke on
the theme “What is IOWN?” (Photo 1). First, President Sawada presented the importance of “Umwelt”(environment or surroundings) in the midst of natural
disasters and a pandemic unexpected in traditional
naturalism, and the significance of IOWN as a “media
connecting different Umwelten.” President Sawada
introduced three demonstration experiments as
IOWN use cases, including the “Avatar Robot Café
DAWN,” which provides a place for people with disabilities to work via the Internet and technology. In
addition, the roadmap for IOWN introduction andresearch and development (R&D) through 2030 forphotonics-electronics converged devices was presented, with the aim of implementing optical materials between chips by 2025, and both between chips
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and within chips by 2030. The new NTT Group Environment and Energy Vision of “NTT Green Innovation toward 2040” was also introduced, simultaneously working to achieve the contradictory aims of“solving environmental problems” and “economic
growth” through reducing environmental impact andcreating innovation that breaks limits through business activities. Under the NTT Group philosophy of“Self as We,” which aims for altruistic coexistence,the company has declared that it will continue towork on three themes: “Ensuring the coexistence of
nature and humanity,” “Improving prosperity for all
people and cultures” and “Maximizing well-being forall,” aiming for the realization of a sustainable society.

Photo 1. Keynote Speech 1: President Sawada.

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Photo 2. K eynote Speech 2: Executive Vice President
Kawazoe.

For more information, see the article entitled “Whatis IOWN?” in this issue.
2.2 Keynote Speech 2
Katsuhiko Kawazoe, Executive Vice President,
Head of Research and Development Planning, NTT,
gave a lecture on the theme of “Road to IOWN 2021”(Photo 2). The IOWN concept, which began with theinvention of optical transistors at one NTT researchlaboratory, now extends beyond the entire NTT
Group to operations worldwide. In his speech, Executive Vice President Kawazoe reported on the progressof the technological developments that make up the
IOWN concept, which was announced in May 2019and is now in its third year, and introduced 15 leading
innovative technologies. In addition, he reported thatthe number of members of the IOWN Global Forumhas increased to approximately 80 in less than two
years. He also noted the establishment of the NTT
IOWN Integrated Innovation Center on July 1, 2021
to accelerate R&D toward realizing IOWN, and the
NTT R&D Authority Team, which includes prominent executives and researchers in each field. For
more information, see the article entitled “Road to
IOWN 2021” in this issue.
2.3 Special Session 1
Masahisa Kawashima, Vice President, Head of
IOWN Development Office, moderated a discussion
between the new leaders of the organization, titled“New R&D leaders talk about steps toward the realization of IOWN” (Photo 3). Hidehiro Tsukano,
Senior Vice President, Head of IOWN Integrated
Innovation Center, which was established in July
2021 in order to realize the core technologies of
IOWN, is from Fujitsu, the supplier side. In addition,
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Photo 3. S pecial Session 1: (from left) Vice President
Kawashima, Senior Vice President Tsukano,and Senior Vice President Oono.

Tomoyoshi Oono, Senior Vice President, Head ofService Innovation Laboratory Group, which aims tocreate a society in which all people can live in a stateof well-being by utilizing Digital Twin Computing(DTC), was involved with service creation in the
R&D department of NTT DOCOMO. In this session,
opinions were exchanged on issues such as how
IOWN will be used to create markets and what activities to proceed with in the future. In response to thequestion, “What is necessary for global vendors toparticipate in IOWN?” Senior Vice President Tsukano pointed out the importance of standardization
through the IOWN Global Forum, and Senior Vice
President Oono pointed out the importance of partners who create services together.
2.4 Special Session 2
This IOWN Global Forum members’ session washeld on the theme of “IOWN Global Forum and its
Initiatives Toward 2030” (Photo 4). The four participants were Gonzalo Camarillo, Vice Chair of theMarketing Steering Committee, who served as themoderator; Clara Li, member of the IOWN Global
Forum and chair of the Technology Steering Committee; Philippe Chanclou, contributor to IOWN Global
Forum activities related to the All-Photonics Network; Katsutoshi Itoh, Chair of the Use Case Working Group; and Masahisa Kawashima, Vice President, Head of IOWN Development Office and Chairof the Technology Working Group. Each panelist
spoke about the current situation and challenges intheir own field of expertise, on themes such as “therelationship between the IOWN Global Forum andother standards organizations” and “the social benefits of IOWN.” Regarding the social benefits of85

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Photo 4. Special Session 2.

IOWN, Vice President Kawashima pointed out thecontribution to energy efficiency, Dr. Itoh spoke on
improved operational efficiency through modeling,
and Dr. Li noted the contribution of building a Data
Centric Infrastructure (DCI) to energy efficiency andsustainability.
3. Technical seminars
The streaming technical seminars provided an
introduction to the latest results from research that
NTT is currently engaged in, as well as a discussion
with guests. This year, seminars were streamed on six
themes: “Application of ICT technology to agriculture and prospects for the future,” “Trusted dataspace:
To overcome the barrier of cross-domain data sharing,” “New era in AI: Think and grow like humans Next generation media processing AI ‘MediaGnosisTM’,” “New user experiences through the interplayof the real and cyber space,” “New relationshipbetween humans and the earth pioneered by blue carbon technology” and “The future pioneered by networking optical lattice clocks.” Here we present an
overview of each seminar.
3.1 Technical Seminar 1
The seminar was held by Hiroshi Yamamoto,
Senior Research Engineer, Supervisor at NTT Network Service Systems Laboratories, under the title“Application of ICT technology to agriculture andprospects for the future.” Television personality
Harry Sugiyama served as MC and Kei Kawana,founder of Neighbor’s Farm, was invited as a guest(Photo 5). “Smart Agri,” one of the six priority areas
for NTT Group efforts to resolve social issues, wasdiscussed in this session under the theme of “Networks and the Agricultural Environment.” The semiNTT Technical Review

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Photo 5. T echnical Seminar 1: (from left) Mr. Sugiyama,
Dr. Yamamoto, and Ms. Kawana.

nar introduced level 3 robotic agricultural machinery
currently being jointly researched with Hokkaido
University, and topics concerning improving availability, multi-layered safety measures and generalpurpose platform development. Ms. Kawana, whoruns a farm founded in Tokyo in 2018 as the first new
farmer under the Act on Urban Farmland Lease
Facilitation, expressed her hope that “significant levels of automation will be implemented while I am
still working in this field, and that agriculture willgrow into an attractive industry for the following generations.”
3.2 Technical Seminar 2
The seminar, titled “Trusted dataspace: To overcome the barrier of cross-domain data sharing,” washeld by Daigoro Yokozeki, Executive Research Engineer at NTT Social Informatics Laboratories. Television personality Harry Sugiyama served as MC andNoboru Koshizuka, Professor, Interfaculty Initiativein Information Studies, The University of Tokyo, wasinvited as a guest (Photo 6). Prof. Koshizuka established the Data Society Alliance (DSA), and is working with governments, industry associations, andNTT with the aim of “creating an environment for thefree distribution of data.” The seminar introduced theconcept of a “trusted data space for cross-domain
information distribution” that can be used to provide
and share the minimum amount of information to theminimum number of parties while remaining
encrypted. In addition, the three elemental technologies of “high-performance encryption,” “secure computation AI” and “next-generation data hubs” wereexplained by engineers having expert knowledge ineach field.

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Photo 6. T echnical Seminar 2: (from left) Mr. Sugiyama,
Executive Research Engineer Yokozeki, andProf. Koshizuka.

Photo 8. T echnical Seminar 4: (from left) Mr. Sugiyama,
Senior Research Engineer Fukatsu, Director
Yagi, CEO Fujii, and Senior Executive Officer
Uematsu.

tion into “Gnosis” in the style of human knowledge,
and then to make a “Diagnosis” based on it.

Photo 7. T echnical Seminar 3: Ms. Nakamura experiencing“MOTESSENSETM”.

3.3 Technical Seminar 3
The seminar, on the topic of “New era in AI: Thinkand grow like humans - Next generation media processing AI ‘MediaGnosisTM’,” was held by SeniorResearch Engineer and Supervisor Yoshinori Kusachi
and Distinguished Researcher Ryou Masumura, bothfrom NTT Computer and Data Science Laboratories.
Television personality Harry Sugiyama served as
MC, and the actress Shizuka Nakamura was invited
as a guest. At the seminar, Ms. Nakamura experienced “MOTESSENSETM,” which helps everyone
discover their own charming individuality, as an
example of an artificial intelligence (AI) that thinks
and is capable of growth like a human. It pointed outthat her “charm factor” or personal appeal was “emotion,” and she was surprised at the detailed diagnosis(Photo 7). Afterward, there was an introductory overview of “MediaGnosisTM,” which is used in MOTESSENSETM. This aims to integrate all media informaNTT Technical Review

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3.4 Technical Seminar 4This seminar featured television personality Harry
Sugiyama as MC, with Naotaka Fujii, CEO of Hacosco Inc., and Michimasa Uematsu, Senior Executive
Officer, CTO, ACCESS Co., LTD. as guests. The
seminar was conducted under the title of “New user
experiences through the interplay of the real andcyber space,” by Takeshi Yagi, Director, Research andDevelopment Planning Department, NTT, and Shinji
Fukatsu, Senior Research Engineer and Supervisor at
NTT Human Informatics Laboratories (Photo 8).
When low power consumption, broadband bandwidth, and low latency are realized, users can receive
all information and choose from it freely dependingon their intentions. During the seminar, user interface(UI) and user experience (UX) experts discussed
what UI and UX should be like in the IOWN era, andwhat the UX should be if real and cyber space areintertwined through the 4D digital platformTM.
3.5 Technical Seminar 5
Television personality Harry Sugiyama served as
MC at this seminar, with guests Kouji Kinjyo, CEOof Sea Seed Co., Ltd., a company working on coral
cultivation and transplantation, and Karibu Suzuki,
CEO of Karibu Collaboration Co., Ltd. and collector
and researcher of juvenile fish. The seminar was conducted on the theme of “New relationship between
humans and the earth pioneered by blue carbon technology” by Katsuhiko Okazaki, Senior ResearchEngineer and Supervisor at NTT Space Environment
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Photo 9. T echnical Seminar 5: (from left) Mr. Sugiyama
and Senior Research Engineer Okazaki.

Photo 10. T echnical Seminar 6: (from left) Mr. Sugiyama,
Dr. Akatsuka, and Research Engineer Arai.

and Energy Laboratories (Photo 9). The focus of thisyear was NTT Space Environment and Energy Laboratories, which tackles environmental and energy
issues from a space perspective. This time, the focus
was on carbon dioxide (CO2) issues with the keyword“blue carbon.” Among the carbon absorbed by the
global ecosystem, the carbon absorbed into themarine ecosystem is known as blue carbon, and carbon absorbed by shallow seas accounts for 35% of
CO2 absorbed on the Earth. At the seminar, a lively
discussion was held, with the introduction of joint
research between Regional Fish Institute, Ltd., a venture company originating from Kyoto University, andNTT.

fiber optic network, was also introduced. The seminar
explained the principle of optical lattice clocks andpointed out the range of applications such as timesynchronization and altitude difference measurement
based on the theory of relativity.

3.6 Technical Seminar 6
Television personality Harry Sugiyama served as
MC for this seminar, with guests Hidetoshi Katori,
Professor, Department of Applied Physics, Graduate
School of Engineering, The University of Tokyo, andTetsuya Ido, Director, Space-Time Standards Laboratory, Radio Research Institute, National Institute ofInformation and Communications Technology. The
seminar was held by Tomoya Akatsuka, SeniorResearch Scientist, NTT Basic Research Laboratories, and Kaoru Arai, Research Engineer, NTT Network Service Systems Laboratories, under the title“The future pioneered by networking optical latticeclocks” (Photo 10). NTT is currently working on
miniaturization of the optical lattice clock invented
by guest Prof. Katori in 2001 through using a chipcalled a planar lightwave circuit for the path the cooling laser follows to an atom. The concept of an “Optical Lattice Clock Network,” a time-space information
infrastructure in which optical lattice clocks areplaced throughout Japan and connected with NTT’s
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4. Exhibits of research results
NTT’s latest technology and research results weredivided into six categories and presented in a virtualexhibit booth. Of these, particularly noteworthy
research is reported below.
4.1 Networks
In the “Networks” category, IOWN’s optical andwireless network technologies and their advanced
control and operational technologies were introduced. At the exhibit “Extreme NaaS for comfortable
quality of end-end communication,” technologies
that optimize performance by using method-independent radio technologies depending on the changing
radio environment, such as analog radio over fiber(RoF) and reconfigurable intelligent surface (RIS),
and also to optimize performance across non-wirelesssystems such as optical networks and application layers were presented (Fig. 1). In addition, the “Allphotonics network transport technology with a variety of optical paths” exhibit featured technologies
such as direct on-demand access between any two
points, including customer sites, and low-latency service linking terminals across domains with end-toend optical paths.
4.2 UX/UI Devices
In the “UX/UI Devices” category, technologies thatseamlessly connect the real world with the cyber88

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Covered with RIS

Terminal camera

Continue video
With RIS control
Blocked by obstruction

Without RIS control

Terminal camera

Stop video

Fig. 1. Control technology for terminal tracking using RIS.

Fig. 2. New UI/UX created by IOWN.

world and maximize human ability through physical,
psychological and social interactions were introduced. In the “Personalized Sound Zone” exhibit,
research on creating sound spaces suitable for users
through advanced control of the surrounding soundspace was exhibited, including noise control technology to block out ambient sounds, and event detection
and localization technology to allow listening torequired sounds. In addition, the exhibit “New UI/UX
created by IOWN” introduced technology for realizing experiences that meet the needs of diverse recipients (able-bodied individuals, people with disabilities, living things and machines) through a fusion of
the real world and cyber space (Fig. 2). Use cases
were demonstrated, such as constructing and experiencing past times and spaces, and visualizing thesounds of daily life to make life easier for people whoare hard of hearing.

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4.3 Security
In the “Security” category, various technologies
were introduced that enable new security by taking
advantage of the unique features of IOWN in order torealize a Smart World and create varied social values.
In the “Secure optical transport network for quantum
computer era” exhibit, cryptographic techniques that
support the security of IOWN, which prevent information from being decrypted even with quantum
computers, were introduced (Fig. 3). In the exhibit, it
was demonstrated that uncompressed 8K images canbe transmitted after encryption and displayed with
virtually no delay using actual hardware. In addition,
the exhibit “Security transparency assurance technology to make trusted networks” presented technology
for providing accurate, leak-free security management through visualization of the configuration andrisks to equipment throughout the supply chain. It
was announced that the goal is to create a world thateveryone can use information and communication
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Fig. 3. Secure optical transport network for quantum computer era.

Fig. 4. Calculating efficient scenario of air-conditioning system.

technology with peace of mind in the IOWN era.
4.4 Computing
In the “Computing” category, the computing technologies and DTC that underpin IOWN, as well as thelatest AI and digital transformation-related technologies and initiatives, were introduced. In the exhibit“Calculating efficient scenario of air-conditioning
system,” technology was introduced that recreates theinterior comfort indicator (predicted mean vote(PMV)) for temperature, humidity and momentum,
and optimizes energy consumption and comfort
simultaneously, all using climate control scenarios
calculated with deep reinforcement learning (Fig. 4).
In the “Initiatives to implement the 4D digital platformTM” exhibit, the 4D digital platformTM, a technology providing high-precision, real-time integration ofdiverse sensor data into the Advanced Geospatial
Information Database with rich semantic information
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was introduced as a foundation supporting DTC,
resolving social issues and creating new value.
4.5 Z
 ero Environmental Impact (Environment
and Energy)
In the category “Zero Environmental Impact (Environment and Energy),” environment and energy technologies were introduced that innovate for the futureof the global environment from a space perspective,
based on the concept of “the Earth, from space.” Theexhibit “Environmental regeneration and adaptation
technologies,” provided an introduction to biologicalconversion technology for oceanic CO2 using genome
editing, and ultra-wide air/ocean observation
technology utilizing satellite Internet of Things (IoT)
sensors (Fig. 5). Based on these technologies, we aim
to reduce environmental impact in the future and torealize an ultra-resilient society that can adapt to global
environmental changes. In the “Space photovoltaic
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Low-earthorbit satellite

Ocean sensors

Establish new sensing technique by developing an IoT sensor that can be
deployed in the oceans with ultra-low-power consumption

Fig. 5. Ultra-wide air and ocean observation technology utilizing satellite IoT sensors.

Fig. 6. Realization of a bio digital twin based on the IOWN concept.

power generation technology” exhibit, technology
was introduced to use solar energy by installing animmense light collector in a geostationary satellite
orbit at an altitude 36,000 km, convert it into lasers
and microwaves, transmit it, receive it in a receiverinstalled on the ground and convert it into energy,
such as electricity.
4.6 Basic Research
In the “Basic Research” category, basic research invarious fields that contribute to the IOWN concept
was exhibited, including R&D on information technology, advanced device and photonics technology,
and medical and bio-technology. In the exhibit “Optical lattice clock (OLC) network technology,” thetechnology of the Optical Lattice Clock Network was
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introduced. Using a network of optical lattice clocks
that can achieve an accuracy more than 100,000 times
higher than that of conventional frequency standards
for communication, we aim to achieve long-term,
stable time synchronization for the fifth-generation
mobile communication system (5G) and 6G, andachieve accurate altitude differential measurements
for disaster prevention. In addition, the exhibit “Medical and healthcare vision: Realization of Bio Digital
Twin” exhibited the efforts to create a bio digital twin
(BDT), a detailed picture of the individual’s body andmind (Fig. 6). The realization of BDTs is expected tocontribute to a brighter future for medical care, in theform of predictions on the mental and physical condition, and hopes for a healthy future.

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5. After the Forum
This year marks the third year of the IOWN initiative. The device is expected to be completed in 2024,
the completion of development of the system in 2025,
and the commercial introduction of IOWN in 2026.
We hope you can feel through this forum that steadyprogress has been made toward the full-scale deploy-ment of IOWN, which is scheduled for 2030. NTT
will continue to make further efforts in R&D in order
to meet your expectations.
Keynote speeches (videos), exhibits, etc. are posted
on our special website “Report on NTT R&D Forum—
Road to IOWN 2021” (https://www.rd.ntt/e/
forum/2021/).

Members of NTT R&D Forum Office: (from left) Takafumi
Mukochi, NTT Service Innovation Laboratory Group; Taeko
Tamada, Research and Development Planning Department,
NTT; Takayuki Onzuka, Research and Development
Planning Department, NTT; Tomohisa Hosoda, Researchand Development Planning Department, NTT; Takayoshi
Mochizuki, Research and Development Planning
Department, NTT; Keita Takahashi, NTT Information
Network Laborator y Group/NTT IOWN Integrated
Innovation Center; Kenichi Hitachi, NTT Science and CoreTechnology Laboratory Group; and Shunsuke Mori,
Research and Development Planning Department, NTT.

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92

External Awards
Medal with Purple Ribbon
Winner: Yutaka Miyamoto, NTT Network Innovation Laboratories
Date: April 29, 2021
Organization: JapanFor development of high-capacity optical transmission scheme
using coherent-multicarrier multilevel modulation.
Optica Fellow
Winner: Shinji Matsuo, NTT Device Technology Laboratories
Date: November 3, 2021
Organization: Optica (formerly OSA)For pioneering contributions to ultra-high-speed and low-powerconsumption membrane lasers.
Visual Movie Award
Winner: Riku Takahashi, NTT Basic Research Laboratories
Date: November 11, 2021
Organization: The Society for Chemistry and Micro-Nano Systems(CHEMINAS)
For “Construction of Vessel-like Tissue Using Fluidic Device
Based on Hydrogel Film.”
Published as: R. Takahashi, A. Tanaka, and M. Yamaguchi, “Construction of Vessel-like Tissue Using Fluidic Device Based on Hydrogel Film,” CHEMINAS 44, IR-01, Nov. 2021.
Highly Commended Paper Award
Winners: Kei Fujimoto, Ko Natori, Masashi Kaneko, Akinori Shiraga, NTT Network Innovation Center
Date: November 25, 2021
Organization: The 31st International Telecommunication Networks
and Applications Conference 2021 (IEEE ITNAC 2021)

For “NIDP: Low-latency Networking without Application Customization in Virtual Machine.”
Published as: K. Fujimoto, K. Natori, M. Kaneko, and A. Shiraga,“NIDP: Low-latency Networking without Application Customizationin Virtual Machine,” IEEE ITNAC 2021, Nov. 2021.
APSEC 2021 Best ERA Paper
Winners: Hiroto Watanabe, Shinsuke Matsumoto, Yoshiki Higo,
Shinji Kusumoto, Osaka University; Toshiyuki Kurabayashi, Hiroyuki Kirinuki, Haruto Tanno, NTT Software Innovation Center
Date: December 8, 2021
Organization: The 28th Asia-Pacific Software Engineering Conference (APSEC 2021)
For “Applying Multi-objective Genetic Algorithm for Efficient
Selection on Program Generation.”
Published as: H. Watanabe, S. Matsumoto, Y. Higo, S. Kusumoto, T.
Kurabayashi, H. Kirinuki, and H. Tanno, “Applying Multi-objective
Genetic Algorithm for Efficient Selection on Program Generation,”
APSEC 2021, Dec. 2021.
2021 IEICE Communications Society OCS Young
Researchers Award
Winner: Takeo Sasai, NTT Network Innovation Laboratories
Date: December 14, 2021
Organization: The Institute of Electronics, Information and Communication Engineers (IEICE) Technical Committee on OpticalCommunication Systems (OCS)
For “Digital Backpropagation for Optical Path Monitoring—Loss
and Dispersion Profile Estimation—.”Published as: T. Sasai, M. Nakamura, S. Yamamoto, E. Yamazaki, H.
Nishizawa, and Y. Kisaka, “Digital Backpropagation for Optical Path
Monitoring—Loss and Dispersion Profile Estimation—,” IEICE
Tech. Rep., Vol. 120, No. 309, OCS2020-39, pp. 61–64, Jan. 2021.

Papers Published in Technical Journals andConference Proceedings
Quantum Remote Sensing under the Effect of Dephasing
H. Okane, H. Hakoshima, Y. Takeuchi, Y. Seki, and Y. Matsuzaki
Physical Review A, Vol. 104, No. 6, 062610, December 2021.
The quantum remote sensing (QRS) is a scheme to add security
about the measurement results of a qubit-based sensor. A client delegates a measurement task to a remote server that has a quantum
sensor, and eavesdropper (Eve) steals every classical information

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Vol. 20 No. 2 Feb. 2022

stored in the server side. By using quantum properties, the QRS provides an asymmetricity about the information gain where the client
gets more information about the sensing results than Eve. However,quantum states are fragile against decoherence, and so it is not clear
whether such a QRS is practically useful under the effect of realistic
noise. Here, we investigate the performance of the QRS with dephasing during the interaction with the target fields. In the QRS, the client

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Papers Published in Technical Journals and Conference Proceedings

and server need to share a Bell pair, and an imperfection of the Bellpair leads to a state preparation error in a systematic way on theserver side for the sensing. We consider the effect of both dephasing
and state preparation error. The uncertainty of the client side decreases with the square root of the repetition number M for small M, whichis the same scaling as the standard quantum metrology. On the other
hand, for large M, the state preparation error becomes as relevant as
the dephasing, and the uncertainty decreases logarithmically with M.
We compare the information gain between the client and Eve. This
leads us to obtain the conditions for the asymmetric gain to be maintained even under the effect of dephasing. Then, we can quantify how
much information the client can gain while preserving the information asymmetricity.

Suppression of Intensity Noises in Forward-pumped
Raman Amplifier Utilizing Depolarizer for Multiple Pump
Laser Sources
H. Kawakami, S. Kuwahara, and Y. Kisaka
Journal of Lightwave Technology, Vol. 39, No. 23, pp. 7417–7426,
December 2021.
We investigate the random intensity noises that occur in forwardpumped distributed Raman amplifier systems. First, we show pump-

NTT Technical Review

Vol. 20 No. 2 Feb. 2022

to-signal intensity noise transfer characteristics, which strongly
depend on the group velocities of pump light and signal light in
optical fiber used as a gain medium. When signal light is in the
C-band, dispersion shifted fiber (DSF) transfers much larger noisecompared with standard single mode fiber. Next, we discuss the origin of the noise induced in pump light. We define the concept of“synthesized polarization” and show that fluctuation in the state ofsynthesized polarization (SOSP) can induce a large gain instability
even if the relative intensity noise (RIN) of each pump laser source isnegligible experimentally. Next, we propose a novel optical depolarizer for pump light. It can simultaneously depolarize pump light
generated by multiple laser sources. Moreover, it can manage opticalphases precisely to suppress the gain instability induced by the fluctuation in SOSP. Finally, we present a measurement of the Q factor ofa 16-QAM signal (32 Gbaud) after 35-km transmission, with andwithout a forward-pumped Raman amplifier. Two pump laser sources
with RINs of –134 to –126 dB/Hz were depolarized by the proposed
depolarizer, and the generated on-off gain was 7 dB. Though amplified signal light was in the C-band and the gain medium was DSF,
16-QAM transmission specifications were successfully improved,
and acceptable noise was observed for 5 hours operation.

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