NTT Technical Review

August 2020 Vol. 18 No. 8

Front-line Researchers

Masaya Notomi, Senior Distinguished Scientist, Nanophotonics Center, NTT Basic ResearchLaboratories

NTT Technology Report for Smart World

Publication of NTT Technology Report for Smart World 2020

Global Standardization Activities
Standardization Activities for Optical Fiber and Cable Technology in International
Electrotechnical Commission

Practical Field Information about Telecommunication TechnologiesSnow-accretion-prevention Sheet for Outdoor Aerial Closure

External Awards/Papers Published in Technical Journals and Conference Proceedings

Front-line Researchers

Exploring New Fields and the World
Masaya Notomi
Senior Distinguished Scientist,
Nanophotonics Center, NTT Basic
Research Laboratories
Overview
In April 2020, NTT formulated a technology roadmap for
implementing the Innovative Optical and Wireless Network(IOWN). Photonic disaggregated computing, one of the key technologies that make up IOWN, is generating great interest as a newarchitecture that shifts from the conventional physical-server-oriented computing platform to a serverless computing platform
based on photonic data planes. We asked Masaya Notomi, a seniordistinguished scientist at the Nanophotonics Center of NTT Basic
Research Laboratories conducting basic research on enabling photonic disaggregated computing, about
his current research efforts and attitude as a researcher.
Keywords: nanophotonics, photonic crystals, all-optical switch

Announcement of research results that attract
attention from around the world—Could you tell us about the research you are currently working on?
Currently, I am working on two themes. One isdeveloping opto-electronic integrated processors
using integrated nanophotonics*1 by further advancing research on photonic crystal devices that operatewith the world’s lowest energy consumption, which
we achieved about 10 years ago. By constructing aphotonic network on a chip, we are trying to breakthrough the limits of conventional integrated-circuit
technology in terms of processing capacity, delay,
and power consumption.
By fully using the nanophotonics technology wedeveloped thus far, we have devised the following
three devices: (i) a nano-photodetector that has thepotential to convert optical signals to electrical signals with zero electric energy consumption; (ii) nanoNTT Technical Review

Vol. 18 No. 8 Aug. 2020

electro-optic modulator that performs electro-opticalconversion with only 6% the energy consumption ofa previously reported modulator; and (iii) opticaltransistor that combines these devices [1] (Fig. 1).
A processor is generally composed of a combination of many logic-operation circuits, each of whichis composed of a combination of logic gates, and eachgate is composed of a combination of transistors.
After developing the optical transistor, we successfully demonstrated the world’s first low-loss, highspeed operation of a small optical logic gate called“Ψ (psi) gate” that operates by optical interference
only. We published a paper about this in March 2020[2] (Fig. 2). With this technology, typical logic operations (AND, XNOR, NOR, etc.) can be carried out
with ultralow delay in a wavelength-independent*1 Nanophotonics: The movement of light and the interaction between objects and light on the nanometer scale. It is a new research field in optics and deals with controlling lightwaves andlight-matter interactions with artificial nanometer-scale structures.

1

Front-line Researchers

Light output

Nano-photodetector

n

p
Au
n
p
Nano-electro-optic modulator

Light input
Load resistance: 24 kΩ

Small footprint(10 × 15 mm2)Light
output2 µm

Fabricated by integrating a photodetector and electro-optic modulator withcapacitance of 1 femtofarad or less.

Fig. 1. Structural diagram of optical transistor using ultralow-capacitance opto-electronic conversion technology.

Silicon wire Ψ gate
Sign
Sign

Bias
al ligal lig

ht A

ligh

t

ht B

Silic

Silic

on

<3

µm

a

Outp

ut

Various Boolean operations (such as AND and NOR) can be executed
simultaneously using the same device.

Fig. 2. Optical logic gate operations using optical interference.

manner by using only a single Ψ gate. By this gate
integrating with a high-speed optical modulator, it ispossible to simultaneously carry out different operations to each wavelength channel (wavelength-division multiplexed parallel computation). Coordinating
various devices, such as operation circuits, will makeit possible to devise the first opto-electronic integrated processor with low latency and low power
consumption that has specific functions.
The second theme, which is a more fundamental
research, is on novel optical phenomena. Part of thisresearch is being conducted jointly with a laboratoryof the Tokyo Institute of Technology, at which I also
hold a post. New nanoscale materials (nanomateriNTT Technical Review

Vol. 18 No. 8 Aug. 2020als), such as carbon nanotubes, have recently been
discovered and have been shown to have various
functions. By applying nanophotonics technology tothese nanomaterials and generating interactions
between nanomaterials and light, it has become possible to discover various new phenomena. For example, simply placing an InAs/InP (indium arsenide/indium phosphide) nanowire on a silicon photonic
crystal*2 will create an optical nano-resonator at thatpoint. We have also succeeded in demonstrating laser*2 Photonic crystal: A structure in which the refractive index is artificially modulated at a period similar to the wavelength of lightin a substance. It can generate various novel properties andstrongly confine light.

2

Front-line Researchers

Plasmonic waveguide(30 × 20 nm) λ2/4000

Confine light to avery small area

Au
Silicon waveguide(400 × 200 nm2)

Graphene
100-fs response speed

Ultrafast nonlinear optical materials
Interaction is enhanced using a miniaturized optical waveguide witha cross-section of 30 × 20 nm. A switch operates in less than one
picosecond with the lowest energy consumption ever reported.

Fig. 3. All-optical switch with graphene-loaded plasmonic waveguide.

oscillation by using nanowires with a size less than
the wavelength of the laser. Moreover, by combining
graphene*3, which has excellent nonlinear opticalcharacteristics, with an extremely small nano-opticalwaveguide (plasmonic*4 waveguide), we have demonstrated an all-optical switch that operates in theultrafast range (less than one picosecond) with low
energy consumption [3] (Fig. 3). What’s more, topological photonics, which applies topological-field
theory*5 in solid-state physics to optics, is a new fieldof optics and expected to produce novel physicalproperties that we do not know what to do with yet.
In this field, we theoretically discovered that a photonic topological insulator can be formed by current
injection. This last topic is a more or less basic
research, in which we cannot anticipate what will be
discovered; thus, it is very exciting.
Our research is one of the technical directions outlined in the “Technology Development Roadmap for
Realizing the IOWN (Innovative Optical and Wireless Network) Concept” announced in April 2020 [4].
To develop a cloud-computing infrastructure thatseamlessly spans multiple datacenters, thereby contributing to achieving computing scaling acrossdevice, edge, and center cloud, we are engaged inbasic research related to high-speed distributedcomputing methods that use the ultrabroadband andlow-latency communication on the All-Photonics
Network.

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Vol. 18 No. 8 Aug. 2020

Find interesting seeds, have fun, andcommunicate how interesting your research iswith other people—Could you tell us what you value when you do
research?
What I value most when doing research is whether
a theme is interesting. For example, we could not see
any outcome when we started researching nanophotonics, but future applications were in sight after
thoroughly investigating them. We are working onthemes as a team, so if we find an interesting seed,someone on the team will substantiate it. All our
research activities may seem successful because wehave published the results of what we succeeded inpursuing, but, of course, some of our activities were
failures. Sometimes we are more likely to fail. That’s
why research activities cannot continue unless theresearchers themselves find them interesting. Also,
unless other people think our activities are interesting, it may be difficult for the value of our research to*3 Graphene: Carbon atoms arranged in a hexagonal lattice withthickness of one atom. Possessing high strength and hardness, italso has the property by which electrons flow faster than any
other substance at room temperature.
*4 Plasmonics: A plasmon is a quantum of plasma oscillation. By
controlling surface plasmons, which have states in which freeelectrons in the metal collectively oscillate and behave as pseudoparticles, light can be propagated into nanocircuits and confinedin a space much smaller than the wavelength of the light.
*5 Topological-field theory: A study of physical properties brought
about by topology and symmetry.

3Front-line Researchers

be socially recognized. I sometimes talk withresearchers in Europe and the United States at academic conferences. If I can’t tell them what’s interesting about my research and share my enthusiasm withthem, I don’t think they will become interested in it.
Moreover, research activities will change according
to phases and levels. It has been more than 10 years
since my last interview. Last time, on finding new
phenomenon, I first thought of combining nanophotonics and devices. The research phase and level thenchanged to applying nanophtonics to circuits then toprocessors. It took us about five years to ensure that
nanophotonics could be useful, and since we knew
what we could use, I discovered another interesting
aspect of the phenomenon. It is said that matters
progress like a spiral, but once certain research iscomplete, the process of rethinking and setting up isrepeated. The interestingness is scattered throughoutthat process. When you are young, your research
theme covers a narrow range; however, after doggedly doing your best, you gradually become able tohandle several themes in parallel. Through close
inquiry, targets of interest will appear one after another. However, I think that we should not let our
research diverge according to our interests only. I also
think that the number of things that we can handle
will increase because we are working as a team.
Therefore, we must be able to communicate how fascinating and interesting our research is. The more
people you have on your team, the more ideas you
will have.
—Is there anything you have done to improve yourself
as a researcher?
I’ve been deliberately working on a new theme.
Large and complex themes, especially, will not be
pursued if we do not consciously work on them,which I think is an essential attitude a researcher
should have. Researchers at NTT, especially those
involved in basic research, may have a medium- tolong-term perspective, and they can continue theirresearch at their own pace and focus on the same
subject throughout their time at NTT without any
short-term pressure on producing results. However, if
a researcher continues to study the same subject for along time, he/she may get bogged down. At suchtimes, I think we must have the courage to change thetheme. I also think if we don’t have the initiative tosearch for new themes, cross fields, or change departments, our feelings about and sensibilities of what isinteresting will fade.
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Now, the research that I am currently working on is
aimed at fabricating an opto-electronic processor
using integrated nanophotonics. We have been able togenerate original results by collaborating withresearchers in other fields. In the past, I didn’t think I
would collaborate with people in the electrical andcircuit fields during my research; however, I haverecently been working with researchers who originally had no experience in my research field.
Such a situation is somehow strange but very interesting. For example, different fields use different
language. So, we first desperately speak in our own
language, thus we cannot understand each other at all.
After we talk many times, however, we start to understand each other. We learn the language of the otherfield and use it to talk about our own field. I find thisprocess of gradually developing common words very
interesting. I think it is important to continue ourresearch while receiving this stimulus. If we don’t
pay attention to that stimulus, it will disappear, andwe will not be able to produce original results.
—What does it mean to be a researcher? What isrequired for researchers today?
I think a researcher can be quite different fromother professions. In most other professions, wages
are paid for the results of the work; however,researchers are paid for what they are doing. Even if
a researcher does not produce results; for example,
even if they don’t achieve anything for 10 years, it isdifficult to evaluate their research work as meaningless. In addition, I think that if rewards are paid only
for achievements, it will be difficult to maintain motivation, especially in the case of basic research with along research span, which wouldn’t allow us to eventalk about interesting research. Given this consideration, it is necessary for researchers to engage in
research every day with the awareness that they are
rewarded for their research activities. Even if we do
not know whether our research results will contributeto society, it is important to take up the challenge withthe spirit and belief that we will contribute, and thatis why I think being interested is an essential elementof research activities.
Then, as I mentioned above, we will be asked to
explain more about our research. It is important that
our research be known as useful to society; it is evenbetter if that research is reported in the mass media.
Moreover, it would be great if we could share theinterestingness of our research and the excitement
about our daily research with the general public, but
4

Front-line Researchersthat is probably too much to ask.
Let’s venture into other fields and the world—Please give a word to all our young researchers.
The number of research topics and fields has
increased considerably, so it is difficult to follow
them all; even so, I think it is very important to consciously attempt to understand other fields. It’s easy
to access information online, and young people,
namely, “digital natives,” are more accustomed tousing the Internet than my “digital immigrant” generation, so I think they work in a good research environment. Unfortunately, I feel that over the past five
years, young Japanese researchers have not as aggressively entered new research fields. Around the world,
new fields and research themes are emerging one
after another, and information about them is undoubtedly available, but young Japanese researchers havenot ventured into these fields. I think that there aremany excellent Japanese researchers, but in this situation, they will not able to obtain original results, andthey will just rehash old ones. Therefore, I’d like ouryoung researchers to watch out for new trends, besensitive to information, and work hard.
So how do we take up a new research theme or
field? One way is to knock on the gates of overseas
research institutes. When I was in my mid-thirties,
about 10 years after I started research, my boss toldme, “Find your own research theme no matter what
you do.” So, I went to study in Sweden for a year,
which was a very good experience. I think it’s beneficial to take the opportunity to go abroad when you areyoung. In the past, being in academia in Japan
enabled us to understand worldwide research trends,
but the situation for giving research presentations ischanging and includes online conferences. That’s
why I think it is necessary to go to international conferences held overseas and research institutes todirectly communicate with many researchers.
It is also important to write papers and publish
research results. Needless to say, peer review in theprocess of publication gives us a new perspective
since the readers are also researchers. Ambiguousness may be allowed when reporting your achievements in your laboratory. When writing a paper,
however, you must make the points of your arguments clear, so it helps to clarify your thoughts in theprocess of writing.
Moreover, considering various items through thatargument may lead to new discoveries. You are probNTT Technical Review

Vol. 18 No. 8 Aug. 2020

ably curious about the number of citations your paper
gets, but you should also be interested in how yourpaper was cited. When the paper is published, it is theresult of what you thought of, but it then can be further developed, changed, and expanded through theinterpretation of the other researchers who cite it. My
paper titled “Theory of Light Propagation in Strongly-modulated Photonic Crystals: Refraction-like
Behavior in the Vicinity of the Photonic Band
Gap”—published in 2000 [5]—was cited in manyother papers, and it became clear that antimatter
affects certain physical phenomena. After that, theinterpretation of my results spread further.
The number of papers you write each year depends
on your research topic and environment, so you may
not need to set a standard. In some institutes, likeuniversities, the number of papers is significant, inothers, such as in-house research institutes, the focus
is on business promotion rather than papers. However, you won’t necessarily finish your research life at
the place you are now. Therefore, it is better to write
papers so that you can be a researcher who can go
anywhere and can clarify your research work and purpose.
—How will you proceed with your research activities
in the future?
There were many prestigious research institutes but
most do not exist today; for example, Bell Labs in theUSA. NTT laboratories, in contrast, uniquely focus
on everything from basic research to applied research.
One can take up large research challenges because he/she has basic research and applied research in one
institute. I want NTT to be a role model for otherresearch laboratories as the number of laboratories
that are firmly engaged in basic research decreases.
However, I don’t think we should be satisfied withdoing research that general universities can do. I also
have a laboratory at the Tokyo Institute of Technology, so I’d like to focus on nurturing the next generation of researchers. I think that the fields I’m working
on will be enriched if I convey the knowledge I haveaccumulated and nurture those researchers. I can’t
accomplish everything myself, so I want new people
to take the lead.
References[1]

Press release issued by NTT, “Realization of an Ultra-energy-saving
Electro-optic Modulator and Highly-efficient Optical Transistor,”
Apr. 16, 2019.
http://www.brl.ntt.co.jp/E/2019/04/latest_topics_201904161802.
html

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Front-line Researchers

[2]

[3]

[4]
[5]

S. Kita, K. Nozaki, K. Takata, A. Shinya, and M. Notomi, “Ultrashort
Low-loss Ψ Gates for Linear Optical Logic on Si Photonics Platform,”
Commun. Phys., Vol. 3, 33, Mar. 2020.
https://www.nature.com/articles/s42005-020-0298-2
Press release issued by NTT, “Demonstration of Ultrafast and Energyefficient All-optical Switching with Graphene and Plasmonic Waveguides,” Nov. 26, 2019.
https://www.ntt.co.jp/news2019/1911e/191126a.html
Press release issued by NTT, “Technology Development Roadmap for
Realizing the IOWN Concept,” Apr. 16, 2020.
https://www.ntt.co.jp/news2020/2004e/200416a.html
M. Notomi, “Theory of Light Propagation in Strongly-modulated
Photonic Crystals: Refraction-like Behavior in the Vicinity of the
Photonic Band Gap,” Phys. Rev. B, Vol. 62, No. 16, pp. 10696–10705,
2000.

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Vol. 18 No. 8 Aug. 2020

Interviewee profile
Masaya Notomi
Senior Distinguished Scientist, Nanophotonics
Center, NTT Basic Research Laboratories.
He received a B.E., M.E., and Ph.D. in applied
physics from the University of Tokyo in 1986,
1988, and 1997. He joined NTT in 1988 where
his research has focused on controlling the optical properties of materials/devices using artificial
nanostructures (quantum wires/dots and photonic
crystals). In addition to his work at NTT, he has
also been a professor at the Department of
Physics, Tokyo Institute of Technology since2017. He received the IEEE/LEOS Distinguished
Lecturer Award (2006) from the Institute ofElectrical and Electronics Engineers/Lasers &Electro-Optics Society, the JSPS prize (2009)
from the Japan Society for the Promotion of
Science, a Japan Academy Medal (2009), and theCommendation for Science and Technology by
the Japanese Minister of Education, Culture,
Sports, Science and Technology (2010). Dr.
Notomi is an IEEE Fellow and a member of theJapan Society of Applied Physics (JSAP), theAmerican Physical Society (APS), and the
Optical Society (OSA).

6

NTT Technology Report for Smart World

Publication of NTT Technology
Report for Smart World 2020
Yuji Maeda, Takayuki Onishi, and Atsuyuki Muramoto
Abstract

NTT Research and Development Planning Department annually releases NTT Technology Report for
Smart World, which presents 11 technologies that will transform technology into a natural presence andmake the world smarter, and other leading-edge activities of NTT. It has now published the 2020 edition
with new information added. This article presents an overview and the main updated points of the report.
Keywords: technology trend, social trend, smart world

1. For Smart World and Natural Technologies
The first edition of NTT Technology Report for
Smart World was released in May 2019. It has been
widely distributed both in hard-copy and as a download. It introduced 11 technologies that will make theworld smarter and more natural. We have updated thetechnology report for the edition 2020 to reflectchanges in technology trends and the progress inNTT’s research and development (R&D) activities
over the last year.
Artificial intelligence is now in practical use inmany services. Such new technologies are bringing
about dramatic changes in our living environment,such as the emergence of unmanned stores and automated driving, and digital transformation of business
operations. The novel coronavirus, which has spreadaround the world in the last several months, is posing
a great challenge to long-established economic andsocial systems and to connections between people. As
exemplified by remote working and distance learning, information and communication technology(ICT) and communication networks are playing asignificant role in supporting humanity’s resilience.
Looking to the future, it is essential to achieve breakthroughs in solving energy problems and developing
innovative medical, materials, and manufacturing
technologies. However, we cannot discuss using suchtechnologies without considering their implication
for cyber security and privacy protection.
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Vol. 18 No. 8 Aug. 2020

The new edition of the technical report reviews the
11 technologies presented in last year’s edition andintroduces the latest technical trends and progress inNTT’s R&D activities. It also explains the specificconfiguration and research roadmap of the Innovative
Optical and Wireless Network (IOWN) and touches
on the establishment of a global forum for IOWN.
2. Eleven Technologies to Update theSmart WorldWe are focusing our R&D efforts on 11 technologies that will transform technology into a naturalpresence and make the world smarter. From technologies that are already being implemented to promisingtechnologies that are still in their infancy, we introduce how these 11 technologies will help to build the
Smart World.
1. Artificial Intelligence
Progress in deep learning has made artificial intelligence (AI) the hottest topic of recent years. Its performance is already higher than that of humans whenit comes to making classifications or judgements
based on learning a large volume of data. What isrequired in the future is technology that operates
based on an understanding of what is deep insidehumans, such as emotion. In using AI, it will be necessary to consider people’s worldviews and ethics.
We are exploring the humanities in collaboration with
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NTT Technology Report for Smart World

Kyoto University with an aim of developing AI thatdeeply understands and coexists with humans.
2. Virtual Reality / Augmented Reality
Virtual reality (VR) has long been used in games.
Attention is now focused on new applications such as
elderly care that uses VR to simulate excursions. In
the future, VR and augmented reality (AR) will makeits way into every facet of human life. Once the realworld and cyberspace are integrated and people canseamlessly move back and forth between the two,
VR/AR technology will play an even more importantrole. In the future, it will be necessary to provide
people with feedback by reproducing the five senses
and by digitizing and modelling people, objects, andenvironments in real time through more advanced
sensing and information gathering in the real world.
Achieving this in a natural way that does not burden
people is a significant research challenge.
3. Human-Machine Interface
The range of uses for human-machine interface(HMI) will expand dramatically in environments
where the real world and cyberspace are closely intertwined. The concept of “ambience” will be importantas this field evolves. We are focusing on technologythat unobtrusively presents information, and technology that uses information imperceptible to humans toprovide natural support from the surrounding environment without hindering people’s activities. To
expand human activities in the real world, we willaddress challenges including how to maximize
human motor function.
4. Cyber Security
The risks to network security from threats such as
cybercrime and cyberterrorism are dramaticallyincreasing. As the real world connects more closelywith cyberspace, attacks on cyberspace are likely toresult in substantial real-world impacts. To addressthese risks, we are developing technology that minimizes security damage while solving the issue ofgrowing security-related operational costs. Furthermore, we are pushing forward on research to create
better systems and norms by encouraging the inclusion of language consistent with technology in laws,
and on a wide range of activities for building communities and developing human resources in the
cybersecurity field.
5. Information Processing Infrastructure
We anticipate system control based on information
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from video and a variety of other sensors to enableoptimal behavior selection and future prediction thatexceeds human capabilities in a range of fields. However, as we work to establish a sustainable society, weare confronted with a number of issues, such as
abrupt changes in the requirements for data processing and high levels of power consumption. Using
data-centric information processing infrastructure
and optical technology, we are striving to exceed thelimits of existing infrastructure and create technologythat can process enormous amounts of data from thereal world at low latency. We are calling this approach“phygital data-centric computing.”
6. Networks
It goes without saying that networks form the foundation of the Smart World. While attention has
focused in recent years on network virtualization anddecentralized networks, conventional networks basedon electronic processing technology are approaching
their limits. To address this problem, we are shifting
to photonics-based technology to create networks
that can address current challenges and achieve low
energy consumption, high quality, large capacity, andlow latency. Moreover, we are rapidly expanding thescope of network connections, including via satellite
communication utilizing MIMO (multiple-input andmultiple-output) and conducted in collaboration with
JAXA, as well as undersea communications.
7. Energy
In an era when companies around the world are
striving to achieve sustainable development goals andpeople’s environmental awareness is rapidly changing, major breakthroughs are needed in research anddevelopment in the energy field. We are developing
technology for using renewable energy efficiently
and reliably by merging our power system and network technologies. We are also working to develop
communication equipment that can operate withmicro-energy. In addition, we are embarking on harnessing innovative energy sources, including fusion
power, space solar power, and lightning charging, allof which are long-cherished dreams of humankind.
8. Quantum Computing
Quantum computing technology, known for its
vastly greater power than conventional computers, isanticipated to be introduced in nearly every industry.
Companies in the U.S., Europe, China, and elsewhereare pushing ahead with development of their own
computers. To develop innovative computing
8

NTT Technology Report for Smart World

technologies, we are taking a number of approaches
to next-generation information processing: from vonNeumann-type post-Moore computing, and non-vonNeumann-type post-Moore computing to rapid andefficient quantum information processing based on
new principles, looking beyond even post-Moore
technology.
9. Biotechnology / Medical Care
Biomedical technology is no longer developed
solely within biology, chemistry, or medicine. As thereal world and cyberspace increasingly merge together, the scope of biomedical technology will also
expand. An example is precision medicine and personalized medicine that is realized through the integration of ICT and AI. We are aiming to realize natural, data-driven medicine and healthcare. For thispurpose, we are using AI to predict potential diseaserisks and to elucidate the mechanisms of disease, anddeveloping high-precision, real-time biomonitoring
technologies and new materials that blend naturally
into the living body. Through such a multi-faceted
approach, we will open a promising path toward aprosperous future for biotechnology and medicalcare.
10. Advanced Materials
Companies around the world are pouring resources
into the pursuit of advanced materials. Examples
include ultrafine materials, nanomaterials, multifunctional materials, and environment-adjustablematerials, all of which are key to next-generation
biotechnology and memory technology. We haveestablished three overall strategic directions: (1)devices that help reduce power consumption andlatency in optical communication, (2) materials thatmake people feel natural and creative, and (3) materials and devices with emergent novel functions. The
development of advanced materials will continue intandem with other technologies.
11. Additive Manufacturing
The term additive manufacturing likely brings 3D
printers to mind, but today the meaning of manufacturing is broader than ever before. We believe that the
future will bring three changes: the personalization of

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biomedical devices, the maturation of photonicselectronics convergence devices, and the realizationof unrivaled manufacturing technology at the nanoscale. We will push ahead with the creation of artificial body systems, the manufacturing of advanced,
complex photonics-electronics convergence devices,and the development of nano-level manufacturing
technologies, including those that will make it possible to control arrays of atoms in three dimensions andthose that will enable direct manipulation of atoms.
3. IOWN is the Platform for Our Future
Last year, we announced our vision for a new communication infrastructure known as IOWN to shift
from electronics to photonics and develop “natural”
technologies that go beyond the limit of today’s digital technology. IOWN is composed of three mainelements: (1) the All-Photonics Network (APN),
which employs photonics-based technology foreverything from networks to terminals; (2) Cognitive
Foundation ® (CF), which connects and controls
everything; and (3) Digital Twin Computing (DTC),
which enables future prediction by integrating thereal and digital worlds.
In October 2019, we joined with partners Intel andSony to announce the establishment of the IOWN
Global Forum. Through this framework, we arepressing ahead with R&D with global partners. We
also released our IOWN technology development
roadmap in April 2020. This roadmap is also
explained in the technology report.
4. Conclusion
NTT Research and Development Planning Department will continue to annually release a summary oftechnology trends, and the strategies and activities of
NTT R&D. The document released and summarized
above is presented on the NTT R&D website [1].
Reference[1]

NTT Technology Report for Smart World 2020, https://www.rd.ntt/e/techreport/

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NTT Technology Report for Smart World

Yuji Maeda

Vice President of R&D Vision Group, Researchand Development Planning Department, NTT*.
He received a Ph.D. in systems information
science from Future University Hakodate, Hokkaido, in 2013. He joined NTT Telecommunication Networks Laboratories in 1991. He is currently managing projects related to generalemergency management such as those concerning natural disaster response and cybersecurity
involving NTT-CERT. He received the Scholarship Encouragement Award from the Institute ofElectronics, Information and Communication
Engineers (IEICE) in 1998. He is a senior member of IEICE and a member of the Institute ofElectrical and Electronics Engineers (IEEE) andthe Japanese Telemedicine and Tele­care Association.
*He became vice president of NTT Space Environment and Energy Laboratories on July 1,
2020.

Atsuyuki Muramoto

Manager, Research and Development Planning
Department, NTT.
He received an M.E. in information scienceand computing engineering from the Universityof Tokyo in 2004. He joined NTT EAST thesame year and has been engaged in corporate
sales, network planning, and research and development in digital signage. He assumed his current position in 2018.

Takayuki Onishi

Senior Manager, Research and Development
Planning Department, NTT.
He received a B.E. and M.E. in information andcommunication engineering and a Ph.D. in engineering from the University of Tokyo in 1997,
1999 and 2019. In 1999, he joined NTT CyberSpace Laboratories and has been engaged inresearch and development on high-quality image
coding and transmission. He is a member of
IEICE.

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10

Global Standardization Activities

Standardization Activities for OpticalFiber and Cable Technology inInternational ElectrotechnicalCommission
Takashi Matsui, Yusuke Yamada, and Noriyuki Araki
Abstract

The International Electrotechnical Commission Technical Committee 86 (IEC TC 86) is a standards
development organization that prepares and decides on international standards in relation to products
used for optical fiber communication. In this article, we provide an overview of standardization activities, introduce topics discussed at meetings in 2019 and 2020, and describe the Japanese standardization
strategy in IEC TC 86.
Keywords: IEC, optical fiber, international standard

1. Introduction
The International Electrotechnical Commission(IEC) is a standards development organization thatsets all of the required standards for electrical andelectronics technologies. In IEC, a Technical Committee (TC) is established for each technical field andholds detailed discussions on the contents, publication, and revision of international standards. TC 86
handles specifications and test methods of opticalproducts in optical communication systems. NTT is
researching and developing technologies and requirements for optical communication systems and actively participating in IEC TC 86 standardization activities since international standards are closely related
to equipment procurement and interconnection.
NTT’s activity involves making proposals for international standardization and discussing documents toguarantee the quality and interoperability of telecommunication networks and product specifications usedin Japan. The International Telecommunication
Union - Telecommunication Standardization Sector(ITU-T) Study Group (SG) 15 is also discussing
international standardization for optical fibers and
NTT Technical Review

Vol. 18 No. 8 Aug. 2020

cables from the viewpoint of requirements for public
communication network systems, and NTT is also
actively participating in this. In IEC, standardization
is mainly conducted from the viewpoint of consistency between procurement specifications for opticalproducts and international standards, and in ITU-T,
standardization is being discussed from the viewpointof securing interoperability of communication systems and requirements. Standardization activities of
IEC and ITU-T are being promoted in close cooperation with each other.
In IEC, TC 86 is in charge of fiber optics technology and its main objective is to establish standards
such as optical, environmental, and mechanicalrequirements of fiber optics products for optical fiber
systems, such as optical modules and devices usedwith optical fiber cables, connectors, and communication equipment. The technical fields of TC 86 areshown in Fig. 1, and its organizational structure isshown in Fig. 2. TC 86 has three Subcommittees(SCs) and makes decisions in each technical field. SC
86A is in charge of optical fibers and cables, SC 86B
is in charge of optical connecting and passive devices,and SC 86C is in charge of optical subsystems and11

Global Standardization Activities

SC 86C
Fiber optic systems
and active devices

Submarine network

Core network
SC 86A
Fibers and cables

Metro network

Access network

SC 86B
Fiber optic interconnecting
devices and passive components
SC: Subcommittee

SC 86A

Fig. 1. Technical fields of IEC TC 86.

Fibers and cables
WG 1 Product specifications & test procedures of optical fibers
WG 3 Product specifications & test procedures of optical cables

SC 86BWG 4 Standard tests and measurement methods
WG 6 Specifications for interconnecting devices and related components
WG 7 Specifications for fiber optic passive components
JWG 8 Product specifications of optical patch cords
Fiber optic systems and active devices
WG 1 Test methods and design of fiber optic communications systems

SC 86CTC 86 (Fiber optics)

Fiber optic interconnecting devices and passive components

WG 2 Sensing method using fiber optic products
WG 3 Product specifications & test methods of amplifiers and dynamic modules
WG 4 Product specifications & test procedures of fiber optic active devices
WG 4 Calibration procedure for optic test instruments
JWG 9 Optical functionality for electronic assemblies

JWG: Joint Working Group

Fig. 2. SCs and Working Groups (WGs) of IEC TC 86.

active devices. It also has 12 Working Groups (WGs)
to discuss specific standards documents. Each WG
proposes new or revised standards for the technicalfield it is in charge of and prepares documents, which
are then issued and reviewed by each SC. This article
describes recent trends in optical fiber and cable stanNTT Technical Review

Vol. 18 No. 8 Aug. 2020

dards being discussed in IEC.
2. Recent trends in standardization for opticalfiber and cable technology
In the field of fiber optics, which IEC TC 86 is
12

Global Standardization Activities

Coating
Optical fiber(a) Conventional optical fiber ribbon

Bonded area
Optical fiber(b) Partially bonded optical fiber ribbon

Fig. 3. Structure of optical fiber ribbon.

responsible for, discussions on the standardization of
optical cables and connecting devices for access systems have been active, especially against the background of the rapid increase in demand for opticalfiber cables in datacenters and the rapid spread of
FTTH (fiber to the home) in Europe and emerging
countries. In SC 86A, which handles optical fiber
cable standards, revisions are being made to opticalfiber and optical fiber ribbon standards in line with
the increasing fiber count and high density of opticalcables, and proposals and discussions are being madeon various testing methods for optical cables in consideration of the usage environment in each country.
A new standardization of the partially bonded optical fiber ribbon, which was developed using ultrahigh-density optical cables, and new test methods forthe friction coefficient and freezing characteristics of
optical cables were proposed by Japan and agreed
upon in SC 86A.
Figure 3 shows an example of the structure of an
optical fiber ribbon. Conventional optical fiber ribbons have restricted flexibility in handling because
they cover multiple optical fibers in a unified manner.
A partially bonded optical fiber ribbon has greatly
improved flexibility, such as being able to be roundedor bent in any direction, by being bonded discretely
in the longitudinal direction. Since the size and test
method were specified on the assumption that theconventional optical fiber ribbon would not deform,
the standard was revised to allow consideration of thepartially bonded optical fiber ribbon, and a new standard document was published as IEC 60794-1-31.
The partially bonded optical fiber ribbon enables theincrease in the mounting density of optical fiber in
optical cables to the upper-most limit, has been used
for ultra-high-density optical cables in Japan, and has
recently begun to be used for densifying high-count
optical cables in other countries.
Standards for optical cable testing methods are alsoessential to objectively guarantee optical cable charNTT Technical Review

Vol. 18 No. 8 Aug. 2020

Fixed load

Movable cablesampleWire

Fixed cable sample

TensionFig. 4. T est procedure of friction coefficient for opticalindoor cable.

acteristics. In Japan, low-friction indoor cables havebeen developed and introduced for indoor wiring, but
because there is no standard test method for the friction coefficient of optical cables, it is difficult toobjectively judge the performance of similar products. Figure 4 shows the friction coefficient test
method for optical cables proposed by Japan. Thismethod is based on the method of testing the coefficient of friction between plastic films and was developed by NTT. As the number of optical cables to beinstalled overseas has increased, the friction between
optical cables has attracted a great deal of attention,
and an agreement was reached to establish a new
standard as one of the methods for testing themechanical properties of optical cables.
In addition, Japan proposed a new test method toevaluate the freezing characteristics of an opticalcable considering its installation in a cold region. The
proposed test method, shown in Fig. 5, was designed
to test the characteristics of an optical cable byinstalling the optical cable in a water-filled conduit,
cooling it, and simulating the freezing environment in
the conduit where the optical cable is actually
installed. NTT is installing and operating optical
13

Global Standardization Activities

Cable

Conduit

Water

Light source

Temperatureinsulator

L2: 1 mPower meter

L1: 5 mFig. 5. New frozen test procedure of optical cable.

cable facilities in various environments in Japan. The
optical cables used in these facilities are evaluatedusing this test method, and the necessary conditions
for countermeasures are specified. There are few
examples of knowledge and proposals concerning thefrozen environment, and it has attracted a great dealof interest from the participating countries.
These new optical fiber cable standards enable us toexpand Japanese technology worldwide, eliminate
inferior products, and objectively guarantee the characteristics of optical cables in the user’s environment.
3. Further activities

deployment of optical fiber and cable technology andhas a strong presence as one of the major countries in
IEC TC 86. Based on NTT’s extensive experienceand knowledge in the introduction and operation of
optical fiber and cable technology, NTT will contribute to the development of international standards that
contribute to the development of optical communication networks by closely cooperating with ITU-T.
NTT will also promote the establishment of nextgeneration optical fiber and cable technology, which
will be indispensable for the implementation of theInnovative Optical and Wireless Network (IOWN)
through both research and development and standardization activities.

Japan has aggressively promoted the domestic

Takashi Matsui

Senior Research Engineer, Access Media Project, NTT Access Network Service Systems Laboratories.
He received a B.E., M.E., and Ph.D. in electronic engineering from Hokkaido University in
2001, 2003, and 2008. He attained the status ofProfessional Engineer (P.E.Jp) in electrical andelectronic engineering in 2009. In 2003, hejoined NTT Access Network Service Systems
Laboratories and has been researching opticalfiber design techniques. He has been contributing
to the activities of IEC TC86 (fiber optic systems) as an expert of SC 86A/WG 1 and WG 3
since 2009. Dr. Matsui is a member of the Institute of Electronics, Information and Communication Engineers (IEICE).

Yusuke Yamada

Senior Research Engineer, Access Media Project, NTT Access Network Service Systems Laboratories.
He received a B.E. and M.E. in environmental
system engineering from Nagaoka University,
Niigata, in 2003 and 2005. In 2005, he joined
NTT Access Network Service Systems Laboratories and has been researching optical fiber cable.
He contributed to the activities of IEC TC 86 as
an expert of SC 86B/WG 4 and WG 6 from 2013
to 2014. He also has been contributing to theactivities of IEC TC 86 as an expert of SC 86A/
WG 1 and WG 3 since 2017.

NTT Technical Review

Vol. 18 No. 8 Aug. 2020

Noriyuki Araki

Senior Research Engineer, Access Media Project, NTT Access Network Service Systems Laboratories.
He received a B.E. and M.E. in electrical andelectronic engineering from Sophia University,
Tokyo, in 1993 and 1995. He joined NTT AccessNetwork Service Systems Laboratories in 1995,
where he researched and developed operationand maintenance systems for optical fiber cable
networks. He has been contributing to standardization efforts in ITU-T SG6 since 2006. He was
the rapporteur of Question 6 of ITU-T SG6 from2006 to 2008 and the rapporteur of Question 17
of ITU-T SG15 from 2008 to 2012. He also
served as the chairman of the ITU-T Focus
Group on Disaster Relief Systems and Network
Resilience and Recovery. He has been the vicechairman of ITU-T SG15 since 2013. He also
contributes to the activities of IEC TC 86 (fiber
optic systems). He received the ITU-AJ award
from the ITU Association of Japan in 2012. He isa member of IEICE.

14

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

Snow-accretion-prevention Sheet for
Outdoor Aerial Closure
Technical Assistance and Support Center, NTT EAST
Abstract

When snow accumulates on closures, it will repeatedly melt and freeze, gradually changing into solid
blocks of ice. These ice blocks may fall from closures and damage vehicles below. This article introduces a snow-accretion-prevention sheet that enables snow to fall off closures before it forms ice blocks.
This is the fifty-ninth article in a series on telecommunication technologies.
Keywords: snow accretion, closure, snow-accretion-prevention sheet

1. Introduction
Snow accretion frequently occurs on overheadequipment during winter in Japan. When snow continues to accumulate on the upper surface of the housing (sleeve) of closures, it will repeatedly melt andfreeze, gradually changing into dense hard blocks ofice. These ice blocks may fall from closures and damage vehicles, as shown in Fig. 1. Consequently, inregions with heavy snowfall, maintenance workers
have to regularly remove snow from closures to prevent such problems. In such heavy-snowfall regions,

measures against snow accretion on closures havetherefore become urgent.
With the above issue in mind, the Technical Assistance and Support Center (TASC), NTT EAST, introduced a countermeasure to prevent snow from accumulating on closures in a previous article [1]. This
article presents outline of the technology for preventing snow accretion and the results of a performanceverification of the technology involving an outdoor
exposure test and describes the procedure for implementing the technology on site.

A car’s windscreen damagedby falling frozen snow

Fig. 1. Snow accretion on a closure and property damage.

NTT Technical Review

Vol. 18 No. 8 Aug. 202015

AttachPractical Field Information about Telecommunication Technologies

No. 3 aerial optical closure sleeve

Completed closure with sheets

Snow-accretion-prevention
sheet (one set of two sheets)

Fig. 2. Closure with the snow-accretion-prevention sheet.

Snow

Snow

Snow

Snow-acSnowcretion-p(1) Snow accumulates on top of closuren sheetClosure

Snow

Snow

reventio

Snow

Snow

Snow

Snow
Water layer
Snow-accretion-p
revention sheetClosure(2) Water layer forms between snow and sheet

SnSnow-acow

cretion-p

reventio

Closuren sheet(3) Snow slides off (due to the lubrication effectof the water layer) before it becomes a blockof ice

Sn

ow
Sn

ow
Sn

ow
Sn

ow

Fig. 3. Process of preventing snow accretion using the sheet.

2. Outline of technology for preventing
snow accretion
To prevent snow from accumulating on a closure, aspecial adhesive sheet with a hydrophilic surface—called a snow-accretion-prevention sheet NichibanCo., Ltd.—is used, as shown in Fig. 2. When wet
snow falls, i.e., snowfall that contains a large amount
NTT Technical Review

Vol. 18 No. 8 Aug. 2020of moisture, accumulates on the sheet, a water layer
forms between the sheet and snow. The lubrication
effect of the water layer makes it possible to prevent
accidents by making the snow fall from the closure
before it becomes a solid block of ice, as shown in
Fig. 3. As often seen in regions along the Sea of Japansuch as Yamagata and Niigata prefectures, such wet
snowfall mentioned above easily attaches to objects [2].
16Practical Field Information about Telecommunication Technologies

Contact angle
Low: hydrophilic surface

High: hydrophobic surface
Water
drop

Water
drop

Surface roughness
Low

High

Fig. 4. Performance parameters of the snow-accretion-prevention sheet.

3. Performance verification of thesnow-accretion-prevention sheet

to observe the difference in snow accretion due to thepresence or absence of the sheet.

3.1 Exposure test
To confirm that the performance of the snow-accretion-prevention sheet is maintained even after it issubjected to exposure of natural phenomena such as
ultraviolet rays in the summer or wind and rain,including typhoons, an outdoor-exposure test was
carried out. The test was conducted in Yonezawa City,
Yamagata Prefecture, where heavy wet snowfall
often occurs. The verification period of the exposure
test was three years, which is the expected qualityassurance period of the sheet. Two verification items
were selected: (i) performance parameters (Fig. 4) of
the sheet after exposure for three years and (ii) snowaccretion condition based on video images. The contact angle with water, which is one of the indices forevaluating the wettability of a substance’s surface,
represents the swelling of a water droplet (i.e., angleof water droplet) that occurs when it is dropped on asubstance. A high and a low value indicate a hydrophobic and a hydrophilic surface, respectively. A
hydrophilic surface is suitable for the sheet because
its hydrophilicity makes it easy to form a water layer
between accumulated snow and the sheet. Moreover,
low surface roughness reduces the friction between
the snow and sheet, making it easier for the snow toslide. During the exposure test, videos of the closuresinstalled at the test site, two with the snow-accretionprevention sheet and the other without, were recorded

3.2 Test results
The rate of change in the performance parameters(contact angle and surface roughness) after the threeyear exposure test are plotted in Fig. 5. Under theassumption that the initial values are 1, the performance of the snow-accretion-prevention sheet ismaintained when the rate of change of the contact
angle is 1.6 times or less and that of surface roughness is 5.0 times or less. Figure 5 indicates that thecontact angle and surface roughness remained in therange in which snow-accretion-prevention performance was maintained, even after exposure for three
years. In the left photograph of Fig. 6, the sameamount of snow accretion was observed on both typesof closures (two with and one without the snowaccretion-prevention sheet); however, in the rightphotograph taken two hours after the left photograph,only the closures with the sheet lost their snow. This
result suggests that a closure with the snow-accretion-prevention sheet is more likely to make accumulated snow slide off (thus less likely to cause snow
clumping into ice blocks) compared to a closure withno sheet. The above results confirm that the physicalproperties of the surface of the snow-accretion-prevention sheet (such as contact angle) did not significantly change, and snow falling from the closures wasregularly observed during the test period; therefore,
the performance of the snow-accretion-prevention

NTT Technical Review

Vol. 18 No. 8 Aug. 202017

Practical Field Information about Telecommunication Technologies

Surface roughness

1.75
1.5

Area of good performance

1.25
1
0.75
0.5
0.25
0

0

1

2

3

Change ratio of surface roughness

Change ratio of contact angle

Contact angle
2

2
Area of good performance

1.5
1
0.5
0

0

Years passed

1

2

3

Years passed

Initial value was set as 1 for contact angle and surface roughness

Fig. 5. Transition in performance parameters.

Prevents snow
from accumulating
and forming
blocks of ice

With sheets

Without sheets

Fig. 6. Exposure field test.

sheet was maintained for three years.
4. Sheet-attachment procedure
One of the advantages of implementing the snowaccretion-prevention sheet is that it can be attachedquickly without requiring any particular skill. The
procedure for attaching the sheet to a closure is
described as follows (see Fig. 7).
(1)	Prepare the closure sleeve, snow-accretionprevention sheet (one set of two sheets), and acloth for cleaning the upper surface of thesleeve to remove dirt before applying the
sheet. Peel off the release sheet along the center line of the back of one snow-accretionprevention sheet and attach the adhesive side
NTT Technical Review

Vol. 18 No. 8 Aug. 2020of the sheet to the sleeve (so it will be temporarily fixed).
(2)	Peel off half of the release sheet from the backside of the snow-accretion-prevention sheet
and attach the sheet to the sleeve. Take care
not to create irregularities or bubbles when
applying the sheet. Repeat for the other half ofthe surface on the closure sleeve.
(3)	Attach the other snow-accretion-prevention
sheet in the same manner as in steps (1) to (3).
(4)	Finally, peel off the protective film (blue) on
the surface of each sheet (completed closure isshown in Fig. 2). Take care not to directly
touch the sheet surface after peeling off theprotective film (doing so will reduce thesnow-accretion-prevention performance of18

Practical Field Information about Telecommunication Technologies

The release sheet of back-side
(2)

(1)

Protective film

(3)

(4)

Fig. 7. Procedure for attaching the snow-accretion-prevention sheet.

the sheet).
5. Conclusion
The snow-accretion-prevention sheet can be
attached to a closure to allow snow to fall off the closure before it forms an ice block. Thus, it preventsequipment problems and accidents due to snow falling off the closure. An outdoor exposure test confirmed that the performance of the snow-accretionprevention sheet can be maintained for three years.
This sheet can be installed by simply attaching it to
the closure.
The TASC will continue to promote technical coop-

NTT Technical Review

Vol. 18 No. 8 Aug. 2020

eration activities aimed at solving on-site issues andcontribute to improving the quality and reliability oftelecommunication facilities.
References
[1]

[2]

Technical Assistance and Support Center, NTT EAST, “Initiatives
Targeting Snow Damage to Communication Facilities,” NTT Technical Review, Vol. 16, No. 12, pp. 42–46, 2018.
https://www.ntt-review.jp/archive/ntttechnical.php?contents=
ntr201812pf1.html
Y. Matsushita and F. Nishio, “Climatological Characteristics Corresponding to the Occurrence of Precipitation Resulting in Snow Accretion in Japan,” Journal of the Japanese Society of Snow and Ice, Vol.
68, No. 5, pp. 425–426, 2006.

19

External Awards
CSS2019 Encouragement Award
Winner: Taishi Nishiyama and Atsutoshi Kumagai, NTT Secure
Platform Laboratories; Akinori Fujino, NTT Communication Sci­
ence Laboratories; Kazunori Kamiya, NTT Secure Platform Labora­
toriesDate: October 23, 2019
Organization: Information Processing Society of Japan (IPSJ)
For “pAUC Maximization Method for Malware Detection.”
Published as: T. Nishiyama, A. Kumagai, A. Fujino, and K. Kamiya,“pAUC Maximization Method for Malware Detection,” Computer
Security Symposium 2019, Nagasaki, Japan, Oct. 2019.
SCIS Paper Award
Winner: Ibuki Mishina, NTT Secure Platform Laboratories
Date: January 28, 2020
Organization: The Institute of Electronics, Information and Com­
munication Engineers (IEICE) Technical Committee on Information
Security (ISEC)For “Can the Logistic Regression in Secure Computation Really
Be Used?”.
Published as: I. Mishina, “Can the Logistic Regression in Secure
Computation Really Be Used?”, 2019 Symposium on Cryptography
and Information Security, Shiga, Japan, Jan. 2019.
NDSS 2020 Distinguished Paper Award
Winner: Takuya Watanabe, NTT Secure Platform Laboratories/
Waseda University; Eitaro Shioji and Mitsuaki Akiyama, NTT
Secure Platform Laboratories; Tatsuya Mori, Waseda University
Date: February 26, 2020
Organization: Internet Society (ISOC)
For “Melting Pot of Origins: Compromising the Intermediary Web
Services that Rehost Websites.”
Published as: T. Watanabe, E. Shioji, M. Akiyama, and T. Mori,“Melting Pot of Origins: Compromising the Intermediary Web Ser­
vices that Rehost Websites,” Proc. of the 27th Annual Network andDistributed System Security Symposium (NDSS 2020), San Diego,
CA, USA, Feb. 2020.
Young Researcher’s Award
Winner: Asuka Matsushita, NTT Network Innovation Laboratories
Date: March 19, 2020
Organization: IEICE
For “Nonlinear Response Compensation for Digital Coherent
Optical Receiver.”Published as: A. Matsushita, M. Nakamura, S. Kuwahara, K. Hori­
koshi, S. Okamoto, and H. Nishizawa, “Nonlinear Response Com­pensation for Digital Coherent Optical Receiver,” Proc. of the 2019
IEICE Society Conference, B-10-28, Osaka, Japan, Sept. 2019.
The Young Scientists’ Prize, the Commendation for Science and Technology by the Minister of Education, Culture, Sports, Science and Technology
Winner: Dai Ikarashi, NTT Secure Platform Laboratories
Date: April 7, 2020
Organization: Ministry of Education, Culture, Sports, Science andTechnology, JapanNTT Technical Review

Vol. 18 No. 8 Aug. 2020

For his research on privacy protection technology that balances
data utilization and protection.
Distinguished Service Award
Winner: Haruka Eitoku, NTT Network Service Systems Laborato­ries
Date: May 14, 2020
Organization: The Telecommunication Technology Committee(TTC)
For his contribution to the formulation of the common intercon­
nection interface for SIP (Session Initiation Protocol) domain nameresolution using the domain name system in TTC and the correspond­
ing standardization work in 3GPP.
Distinguished Service Award
Winner: Takeshi Seki, NTT Network Service Systems Laboratories
Date: May 14, 2020
Organization: TTC
For his contribution to the international standardization concerning
equipment functions and protection/restoration of transport net­
works.
Distinguished Service Award
Winner: Kaoru Arai, NTT Network Service Systems Laboratories
Date: May 14, 2020
Organization: TTC
For his contribution to the international standardization concerning
time- and frequency-synchronization technology for packet transport
networks.
Best Paper Award
Winner: Daisuke Sato, Tatsushi Matsubayashi, Masato Fukuda,
Kyota Tsutsumida, NTT Service Evolution Laboratories; Akira
Nakayama, NTT Research and Development Planning Department;
Hiroyuki Toda, NTT Service Evolution Laboratories
Date: May 23, 2020
Organization: The 12th Forum on Data Engineering and Informa­tion Management (DEIM2020)
For “Composite Spatio-temporal Prediction Model Using Residual
Regression.”
Published as: D. Sato, T. Matsubayashi, M. Fukuda, K. Tsutsumida,
A. Nakayama, and H. Toda, “Composite Spatio-temporal Prediction
Model Using Residual Regression,” DEIM2020, Fukushima, Japan,
Mar. 2020.
Award from Chairman of the Council for Info-communications Promotion Month
Winner: Yoshinori Goto, NTT Network Technology Laboratories
Date: May 29, 2020
Organization: The Council for Info-communications Promotion
Month, Ministry of Internal Affairs and Communications
For his contribution to the promotion of international standardizationin the International Telecommunication Union - Telecommunication
Standardization Sector (ITU-T).

20

Papers Published in Technical Journals and Conference Proceedings

12th Special Activity Award
Winner: Katsuhiro Ajito, NTT Device Technology Laboratories
Date: June 4, 2020
Organization: The Institute of Electrical Engineers of Japan (IEEJ)
For his contribution to the activation of research activities throughthe SENSOR SYMPOSIUM on Sensors, Micromachines andApplied Systems and the improvement of IEEJ’s business presence
through collaboration with other academic societies and the local
host communities. This award was given to the executive committeeof the SENSOR SYMPOSIUM on Sensors, Micromachines andApplied Systems.
Best Late-Breaking Report Honorable Mention Video
Award
Winner: Mitsuhiro Goto, Masanori Yokoyama, and Yumiko Matsuu­
ra, NTT Service Evolution Laboratories
Date: June 9, 2020
Organization: 15th Annual IEEE/ACM International Conference on
Human-Robot Interaction (HRI 2020)

For “Impression Evaluation of Presentation by a Communication
Robot in an Actual Exhibition.”
Published as: M. Goto, M. Yokoyama, and Y. Matsuura, “Impression
Evaluation of Presentation by a Communication Robot in an Actual
Exhibition,” Proc. of HRI 2020, pp. 218–220, Mar. 2020.
Technical Committee on Communication Quality Research
Encouragement Award
Winner: Yuichiro Urata, Masanori Koike, and Kazuhisa Yamagishi,
NTT Network Technology Laboratories
Date: July 16, 2020
Organization: IEICE Technical Committee on Communication
Quality
For “An Applicability of ITU-T Recommendation P.1203 Model to
VR Video Streaming.”
Published as: Y. Urata, M. Koike, and K. Yamagishi, “An Applicabil­
ity of ITU-T Recommendation P.1203 Model to VR Video Stream­ing,” IEICE Tech. Rep., Vol. 119, No. 125, CQ2019-52, pp. 79–83,
July 2019.

Papers Published in Technical Journals andConference Proceedings
Effects of Rosin-powder Application on the Frictional
Behavior Between a Finger Pad and BaseballT. Yamaguchi, N. Yamakura, S. Murata, T. Fukuda, and D. Nasu
Frontiers in Sports and Active Living, Vol. 2, 30, April 2020.
Rosin powder, which is composed of magnesium carbonate pow­
der and pine resin, is often used as a grip-enhancing agent in baseballpitching. However, the effect of rosin powder on friction at the base­ball–human finger interface remains unclear. This study aimed toinvestigate the effect of rosin powder on the friction coefficient
between a baseball and finger using sliding friction tests. Ten young
adult males participated in this studyand were asked to slide the index
finger of their dominant hand over the leather skin of a baseballadhered to the force sensor, which was not a real baseball pitchingsituation. Our findings suggest that rosin-powder application stabi­lizes friction under both dry and wet conditions, that is, there was lessdependence of the friction coefficient on the normal force and lessvariation in the friction coefficient among individuals. For most par­ticipants, the friction coefficient was not necessarily increased by thepresence of rosin powder at the finger pad–leather sheet interface
under dry conditions. However, under wet conditions, rosin-powder
application increased the friction coefficient compared with under the
non-powdered condition in the large normal force condition, indicat­
ing the efficacy of rosin powder as a grip-enhancing agent.

NTT Technical Review

Vol. 18 No. 8 Aug. 2020

Behavioral Measures in a Cognitive-motor Batting Task
Explain Real Game Performance of Top Athletes
D. Nasu, M. Yamaguchi, A. Kobayashi, N. Saijo, M. Kashino, andT. Kimura
Frontiers in Sports and Active Living, Vol. 2, 55, May 2020.
Excellent athletic performance in baseball and softball batting isachieved through the momentary cognitive-motor processes. How­ever, in previous studies, cognitive and motor processes were investi­
gated separately. In this study, we focused on the difference in thetime of swing onset (a delta onset) during a batting task where 17 elite
female softball batters hit balls randomly thrown at two different
speeds by pitchers. The delta onset included both cognitive and motor
processes because the batters needed to anticipate the ball speed anddiscriminate their swing motion according to the time-to-contact.
Then, we investigated the relationship between the delta onset andbatting outcomes of the batting task and the relationship between theexperimental outcomes and actual batting performance (batting aver­age) over a season.We used path analysis to clarify the structure of thecognitive-motor processes and consequent performance. We foundthat the batters who had a larger delta onset attained superior batting
outcomes (i.e., higher exit velocity and lower miss ratio) in the bat­ting task, and these experimental outcomes explained 67% of thebatting average in real games. On the other hand, the cognitive scores(judgement accuracy and rapidity) obtained from a button pressingtask, where batters responded to a ball by pressing a button instead of
actually swinging, explained only 34% of the batting average.

21

Papers Published in Technical Journals and Conference Proceedings

Therefore, our model quantitatively describes the key cognitivemotor structure for athletes and can partially predict a batter’s perfor­
mance in real games. These findings suggest that it is important toemploy both cognitive and motor processes in performing tasks, suchas this batting task, to properly evaluate a batter’s actual ability.

Classification of Viewing Abandonment Reasons for
Adaptive Bitrate Streaming
S. Takahashi, K. Yamagishi, P. Lebreton, and J. Okamoto
The 12th International Conference on Quality of Multimedia
Experience (QoMEX), May 2020 (online).
As adaptive bitrate streaming services have spread, it has become
more important for video streaming providers to control video qual­
ity and prevent viewing abandonments. However, since viewing
abandonments are caused not only by quality degradations but also
by a lack of users’ interest in contents, it will first be necessary to
clarify how quality and/or content affect viewing abandonments. To
investigate this, we conducted an adaptive bitrate streaming experi­
ment and developed a viewing-abandonment-reason-classification
model that classifies abandonment reasons into quality or content.
Using training data, we developed four models (logistic regression,classification tree, random forests, and support vector machine)where feature variables related to application quality, users’ operation
behaviors, and the attributes of viewed contents were used as explan­
atory variables. These four models were validated by using validation
data. From the results, the support vector machine model was consid­
ered to be the best since it obtained relatively good validation results
and did not appear to be overtrained.

Discontinuous and Smooth Depth Completion with Binary
Anisotropic Diffusion Tensor
Y. Yao, M. Roxas, R. Ishikawa, S. Ando, J. Shimamura, and T.
Oishi
arXiv:2006.14374 [cs.CV], June 2020.
We propose an unsupervised real-time dense depth completionfrom a sparse depth map guided by a single image. Our method gen­erates a smooth depth map while preserving discontinuity between
different objects. Our key idea is a Binary Anisotropic Diffusion
Tensor (B-ADT), which can completely eliminate the smoothness
constraint at intended positions and directions by applying it to varia­
tional regularization. We also propose an Image-guided Nearest
Neighbor Search (IGNNS) to derive a piecewise constant depth map,
which is used for B-ADT derivation and in the data term of the varia­
tional energy. Our experiments show that our method can outperform
previous unsupervised and semi-supervised depth completion meth­ods in terms of accuracy. Moreover, since our resulting depth map
preserves the discontinuity between objects, the result can be con­verted to a visually plausible point cloud. This is remarkable sinceprevious methods generate unnatural surface-like artifacts between
discontinuous objects.

User Evaluation of Expression and Representation of Privacy Policy’s Content
S. Shinoda, F. Magata, A. Fujimura, S. Kubota, and N. Chiba
IPSJ Journal, Vol. 61, No. 6, pp, 1146–1174, June 2020.
Recently, many online services are being provided for digital
devices. Service providers collect a lot of users’ personal data throughthese online services and process them for various purposes. TheyNTT Technical Review

Vol. 18 No. 8 Aug. 2020

provide a privacy policy to give users opportunities to access theinformation about their data processing. However, in most cases, theprivacy policy is too long and contains too many legal terms for the
average user to understand. As the best way to express and represent
a privacy policy’s content remains unclear, some service providers
have trouble designing one, and some intend to hide their privacy
policies. For both protecting user privacy and promoting service
providers’ business, it is important to reveal how users react toexpression and representation of privacy policy. To investigate this,we conducted a focus group interview and web survey then evaluatedsome privacy policy expressions and representations.

Polylog-overhead Highly Fault-tolerant Measurementbased Quantum Computation: All-Gaussian Implementation with Gottesman-Kitaev-Preskill Code
H. Yamasaki, K. Fukui, Y. Takeuchi, S. Tani, and M. Koashi
arXiv:2006.05416 [quant-ph], June 2020.
Scalability of flying photonic quantum systems in generating
quantum entanglement offers a potential for implementing largescale fault-tolerant quantum computation, especially by means ofmeasurement-based quantum computation (MBQC). However, exist­
ing protocols for MBQC inevitably impose a polynomial overhead
cost in implementing quantum computation due to geometrical con­straints of entanglement structures used in the protocols, and thepolynomial overhead potentially cancels out useful polynomial
speedups in quantum computation. To implement quantum computa­tion without this cancellation, we construct a protocol for photonic
MBQC that achieves as low as poly-logarithmic overhead, by intro­
ducing an entanglement structure for low-overhead qubit permuta­tion. Based on this protocol, we design a fault-tolerant photonic
MBQC protocol that can be performed by experimentally tractablehomodyne detection and Gaussian entangling operations combinedwith the Gottesman-Kitaev-Preskill (GKP) quantum error-correcting
code, which we concatenate with the 7-qubit code. Our fault-tolerant
protocol achieves the threshold 7.8 dB in terms of the squeezing levelof the GKP code, outperforming 8.3 dB of the best existing protocol
for fault-tolerant quantum computation with the GKP surface code.
Thus, bridging a gap between theoretical progress on MBQC andphotonic experiments towards implementing MBQC, our results
open a new way towards realization of a large class of quantum
speedups including those polynomial.

Efficiently Generating Ground States Is Hard for Postselected Quantum Computation
Y. Takeuchi, Y. Takahashi, and S. TaniarXiv:2006.12125 [quant-ph], June 2020.
Although quantum computing is expected to outperform universal
classical computing, an unconditional proof of this assertion seems tobe hard because an unconditional separation between BQP and BPP
implies P≠PSPACE. Because of this, the quantum-computationalsupremacy approach has been actively studied; it shows that if theoutput probability distributions from a family of quantum circuits canbe efficiently simulated in classical polynomial time, then the poly­
nomial hierarchy collapses to its second or third level. Since it is
widely believed that the polynomial hierarchy does not collapse, thisapproach shows one kind of quantum advantage under a plausible
assumption. On the other hand, the limitations of universal quantum
computing are also actively studied. For example, it is believed to be
impossible to generate ground states of any local Hamiltonians inquantum polynomial time. In this paper, we give evidence for this22Papers Published in Technical Journals and Conference Proceedings

impossibility by applying an argument used in the quantum-compu­
tational-supremacy approach. More precisely, we show that if groundstates of any 3-local Hamiltonians can be approximately generated inquantum polynomial time with postselection, then the counting hier­archy collapses to its first level. Our evidence is superior to the exist­
ing findings in the sense that we reduce the impossibility to an
unlikely relation between classical complexity classes. Furthermore,
our argument can be used to give evidence that at least one 3-local
Hamiltonian exists such that its ground state cannot be represented bya polynomial number of bits, which may be related to a gap between
QMA and QCMA.

NTT Technical Review

Vol. 18 No. 8 Aug. 2020

Polylog-overhead Fault-tolerant Measurement-based
Quantum Computation by Homodyne Detection
H. Yamasaki, K. Fukui, Y. Takeuchi, S. Tani, and M. Koashi
15th Conference on the Theory of Quantum Computation, Com­
munication and Cryptography (TQC2020), June 2020 (online).
We have proposed a novel quantum state that can be used as auniversal resource of measurement-based quantum computat ion(MBQC). By utilizing this state, we can perform quantum computing
more efficiently than before. We have also analyzed the fault-toler­ance of our MBQC method and confirmed that our method has ahigher error-correcting threshold value than existing ones by numeri­
cal calculations.

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