NTT Technical Review

September 2023 Vol. 21 No. 9
View from the TopTeruyuki Kishimoto, President & CEO, NTT Anode Energy

Front-line ResearchersNoboru Harada, Senior Distinguished Researcher, NTT Communication Science Laboratories

Rising ResearchersTakashi Matsui, Distinguished Researcher, NTT Access Network Service Systems Laboratories

Feature Articles: Launch of APN IOWN1.0 Service

APN Service-provision Activities

Road to IOWN at NTT EASTNTT WEST’s Efforts in Providing APN Services

Delay Managed Network for APN IOWN1.0

Feature Articles: Keynote Speeches and Workshop Lectures at Tsukuba Forum 2023
NTT as a Creator of New Value and Accelerator of a Global Sustainable Society

Past and Future Prospects for Advanced Operation of Access Network Facilities



Low-latency and Energy Efficient Technologies for New Optical Access Networks

Wireless Technologies for Accelerating High-capacity Transmission, Low Energy, andApplication-area Expansion

Global Standardization Activities
A Report on ASTAP and WTSA-24 Regional Preparatory Meeting

External Awards

View from the Top

NTT Anode Energy Aims to Become a
Leading Company in Smart Energy
Business to Help Society Achieve
Carbon Neutrality
Teruyuki Kishimoto
President & CEO, NTT Anode Energy
Abstract

Under thorough environmental, social, and corporate governance management, NTT Anode Energy maximizes the potential of renewable energy
and promotes Earth-friendly economic activities. As a new player in theenergy field, the company is driving the NTT Group’s efforts to reduce its
environmental impact. We interviewed Teruyuki Kishimoto, president &CEO, NTT Anode Energy, about the company’s core businesses and his
mindset as a top executive.
Keywords: renewable energy, carbon neutrality, local production for local
consumption of energy

Connecting the ICT and electric
power businesses—It has been a little more than a year since you took
office as president and CEO of NTT Anode Energy.
Looking back over the past year, could you tell us
about your feelings and the current status of NTT
Anode Energy?
I left NTT WEST, where I spent 23 years, tobecome president & CEO of NTT Anode Energy inJune 2022. The business I oversee has shifted significantly from telecommunications to electric power,
and the speed of change, scale of investment, andnature of capital investment differ from the factors in
the telecommunications industry where I worked formany years, so I do feel like I’ve changed jobs. While
making the most of my knowledge and experience inthe telecommunications facility business that I had
been in charge of at NTT WEST, I am keeping my ear
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Vol. 21 No. 9 Sept. 2023

to the ground and studying trends in the electric
power business and society as a whole.
The environment surrounding the energy and electric power business is changing dramatically as
exemplified by the global trend toward decarbonization, unstable energy-resource prices, and reforms topower systems owing to the increased introduction ofrenewable energy and the decline in thermal-power
generation. In Japan, a law for promoting the smoothtransition to a decarbonized growth-oriented economic structure, called the Green Transformation(GX) Promotion Law, came into effect in June 2023
to accelerate GX initiatives aimed at both achieving astable energy supply and decarbonization, includingthat of the power system.
Under these circumstances, NTT Anode Energy, as
an expert group in the field of energy and electric
power in the NTT Group, intends to play a role inbridging between the information and communication technology (ICT) and electric power businesses.
1View from the Top

Focusing on our four core businesses (explainedlater), we are promoting decarbonization and local
production for local consumption of energy in cooperation with NTT Group companies and partners.
This initiative takes into account the creation of acircular-economy society, as stated in NTT’s new
medium-term management strategy announced in
May 2023, and aims to help achieve carbon neutrality
in Japan by 2050. We are expected to contribute to the
NTT Group and society as a whole by achieving the
NTT Group’s environment and energy vision andcreating a smart energy business in Japan and overseas. Although we are under a lot of pressure, I find itvery rewarding.
—What is the current situation of the energy and electric power industry? And how is NTT Anode Energy
approaching this situation?
Over the last 10 to 20 years, the energy and electric
power industry has faced many challenges.
Telecommunications is evolving not day by day, but
minute by minute. The energy and electric powerbusiness too has undergone major changes. In preparation for power shortages in summer and winter inJapan, electric power companies are requested toensure stable power supplies; in fact, some experts
are calling for planned power outages. The form of
power generation has been required to change torenewable energy, and deregulation, including theseparation of power generation, transmission, and
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Vol. 21 No. 9 Sept. 2023

distribution and the liberalization of the retail markets for electricity and city gas, has progressed. The
electric power industry needs to address these challenges and create new businesses that are environmentally responsible.
To address these situations, about 3000 energy andelectric power experts within the NTT Group joined
NTT Anode Energy. In addition, specialists from outside the Group around the world were hired midcareer. NTT Anode Energy is truly an organizationthat embodies diversity and inclusion, and as a compass that guides all employees in the direction inwhich they can work together, we have set up ourcompany’s purpose as the “Anode Way,” namely,“Creating a new common sense in energy throughtechnology and inquisitiveness.” Created by our
employees, the Anode Way is written in simple
Japanese with easy-to-understand explanations.
We also compiled “Our Story,” which is our history
to be shared with all employees. Tracing the footstepsof our predecessors, we discovered the fact that in
1962, they installed a small solar-power generator ona public telephone box and tested it for practical use.
After the Great East Japan Earthquake in 2011, they
supplied electricity through large-scale solar-power
generation, which we later launched as a business.
These examples gave us the opportunity to realizethat what our predecessors have endeavored and built
have become our great assets.

2

View from the Top

Developing a smart energy business with a value
chain consisting of four core businesses—It has been four years since the foundation of NTT
Anode Energy, and its identity has been steadily
established. Could you tell us about the businesses
you are focusing on?
We are currently operating four businesses: GreenPower Generation Business, Local Grid Business,
Consumer Energy Business, and Construction/
Maintenance Operation Business. We have built avalue chain through these businesses and are developing it as a smart energy business.
In the Green Power Generation Business, we aredeveloping renewable-energy power plants, such as
solar, wind, geothermal, biomass, and hydropower, tomeet the green power needs of customers and NTT
Group companies. We intend to build power plants
without causing large-scale deforestation and otherissues to protect ecosystems and living environments.
In August 2023, we acquired shares in Green PowerInvestment Corporation in collaboration with JERA

Co., Inc.
In the Local Grid Business, we promote energy
independence and local production for local consumption of energy by using stable, local renewableenergy sources. Since each region faces different
challenges, we will address these challenges in a waythat matches local circumstances and contribute to
the circulation and revitalization of local economies
while achieving the goal of carbon neutrality. Seven
municipalities supported by NTT Anode Energy havebeen selected as leading decarbonization regions by
the Ministry of the Environment.
In the Consumer Energy Business, we supply corporate customers with green power generated by ourpower plants. We are particularly interested in corporate power purchase agreements (PPAs) and believethat off-site PPAs, which are not subject to physicalconstraints of the customer’s location and equipment
and are able to flexibly meet increases or decreases in
power usage, will prove even more valuable in the
future.
In the Construction/Maintenance Operation
Business, we provide construction, maintenance, andmonitoring services of electric power equipment forvarious facilities such as solar-power plants andlarge-scale datacenters. With highly skilled technicians who monitor and control equipment at two
operation centers located in eastern and westernJapan, and technicians at maintenance stations
throughout Japan, we provide design, monitoring,and maintenance of NTT Group’s telecommunications power-supply equipment and our leading-edge
technical capabilities.
—So these four businesses will make decarbonizationand local production for local consumption of energy
a reality, right?
We have begun specific efforts in collaboration
with various local governments and partner companies. In 2023, we have been working with NEC
Corporation to achieve a decarbonized society. NTT,
with its environment and energy vision (NTT Green
Innovation toward 2040), and NEC, with its NEC
Environmental Policy and the Course of Action for
Climate Change Toward 2050, have joined forces inthis new initiative to reduce environmental impact. In
addition to reducing NEC Group’s Scope-2 greenhouse-gas emissions as NEC purchases green powerfrom the NTT Group, we aim to reduce NTT Group’s
Scope-3 emissions as NEC manufactures and supplies its products to the NTT Group by using green

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3

View from the Top

power, thereby promoting environmental management for both companies.
In collaboration with NTT DOCOMO and NTT
Smile Energy, since May 2023, we have been conducting field experiments on household solar-power
generation and storage batteries to build a decarbonized society. NTT DOCOMO, which aims to achievecarbon neutrality by providing the docomo Denki
Green retail electricity service, and NTT Smile
Energy, which has knowledge of solar-power generation and storage batteries, are collaborating to provide home energy services using solar-power generation and storage batteries for limited areas. Customers
can install solar panels and storage batteries in theirhomes at a fixed monthly fee and no initial cost. NTT
DOCOMO is supporting sales of this service andinvestigating future collaboration with the docomo
Denki Green service through data analysis while
NTT Smile Energy is conducting usage analysis as aprovider of this service. NTT Anode Energy is investigating the expansion of its services as an electricity
retailer and the future possibility of cooperation in thefield of supply-and-demand adjustment.

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Vol. 21 No. 9 Sept. 2023

Inspiring myself and colleagues toward goals andsharing the joy of achieving them
—In the previous “View from the Top” interview(2020), you told us about the importance of passing
on tacit knowledge. How do you pass on tacit knowledge in an organization employing diverse people as
NTT Anode Energy does?
For example, different industries use different systems and terminology. Since we bring together
employees from a variety of backgrounds, mutual
understanding of terminology and contexts is one
type of passing on tacit knowledge. After COVID-19
was downgraded to a Class 5 infectious disease inJapan in May 2023, the office-attendance rateincreased to about 50%, and hybrid communication
combining remote and face-to-face communication
has become crucial. Verbal communication between
people in face-to-face meetings accounts for 20 to
30% of communicated information, and non-verbal
communication, such as the shared atmosphere,accounts for the majority of the communicated information. Therefore, I would like employees to try tounderstand such atmosphere in communicating with
one another.
We have employees in their 60s, who have been
active on the front lines for many years, and young
employees in their 20s and 30s; thus, this age difference of 30 to 40 years represents a huge experiencegap. Under these circumstances, to pass on tacit
4View from the Top

knowledge of senior employees, we have created asystem through which senior employees can teachyoung employees in an easy-to-understand mannerby simplifying the language. Young employees ask
questions of senior employees who have been
responsible for maintenance and inspection of equipment and facilities so that tacit knowledge can bepassed on in their daily work. In fact, today (the dayof the interview), our senior employees were being
bombarded with questions from our young employees over lunch. Through these efforts, we hope tocreate a virtuous cycle in which young employees
become aware of the knowledge and qualifications
they must acquire, voluntarily improve their skills,
and pass these skills on to ones junior to them. When
this cycle is created, tacit knowledge becomes explicit knowledge. Toward the upcoming Innovative
Optical and Wireless Network (IOWN) era, I want tocommunicate the areas in which NTT Anode Energy
should focus on and the work we should engage in. In
addition to the cycle of knowledge, I want to create a
grand design of new electric-power equipment andfacilities by making full use of ICT.
—What do you value as a top executive? And what isyour message to everyone?
As in the past, I value decision making and execution. I also value communication and action formyself to become the source of such execution. I
designated the following statement as my purpose, “Iwill become an ‘energy source’ that provides vitality
to the NTT Group and local communities.” To
achieve this purpose, I declared, “I will play a role asa guiding light in creating a safe and secure culture inwhich people can look ahead and keep moving forward, inspire myself and colleagues toward goals,
and share the joy of achieving them. I will also keep
communicating with my colleagues, who are boundby bonds, respect each other’s goals, and embody andput into practice those goals to grow together.” I havealso asked executives of NTT Anode Energy to set
their purpose as well.
I try to keep inspiring employees and bringing them

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together, even if it is little by little every day. To that
end, I want to overcome the physical distance
between our head office in Tamachi, Tokyo and thefield to minimize the disparity in feelings and information as much as possible. Therefore, I visit eachprefecture to listen to the voices of our employees andenergize them.
I also want to communicate with people other thanemployees and send the following messages.
To researchers and engineers. As a global leader inthe development of IOWN, I hope that you will carry
your marketing ideas with you as you move towardpractical application. I also expect you to value diversity and create innovation through contact with others
outside the NTT Group. We cannot advance a smart
energy business alone. We will continue to be incharge of operations of such business, and I would
like you to conduct research and development that
contributes to those operations.
To customers. We want to faithfully meet yourexpectations for the brand image of NTT. In this eraof rapid technological progress in areas such as storage batteries and hydrogen power generation, let’s
work together to create something new. To that end,
we welcome requests from the viewpoint of customers and will leverage the knowledge that NTT has
cultivated to provide services in the energy field.

Interviewee profile
Career highlights
Teruyuki Kishimoto joined NTT in 1986 andbecame president and CEO of NTT Field Technoin 2014. In 2017, he became a member of theboard of NTT WEST, senior executive manager
of Kansai Regional Headquarters, and generalmanager of the Osaka Branch. In 2019, hebecame executive vice president and concurrently executive manager of Network Department,
Plant Headquarters, NTT WEST. He assumed his
current position in June 2022.

5

Front-line Researchers

Pursuing Both Basic Research andInternational-standardization
Activities to Make Technology Usefulto Society
Noboru Harada
Senior Distinguished Researcher,
NTT Communication Science
Laboratories
Abstract

As remote conferencing is becoming commonplace and theterm “metaverse” is frequently appearing in the media, society’s
attention is increasingly focused on communication using video
and audio. Although the role of video in such communication
tends to gain greater interest, the role of audio—for example, increating a sense of immersion—is also significant. Noboru Harada, a senior distinguished researcher at NTT Communication Science Laboratories, has been researching speech and acoustic
communication for more than 20 years and is currently focusing on research and standardization ofnatural and highly functional speech and acoustic communication technology to achieve, for example,
selective transmission of sounds you want to convey and sounds you want to hear. We interviewed him
about his research accomplishments, standardization activities, and attitude as a researcher.
Keywords: speech/audio coding, immersive communication, semantic segmentation

Contributing to society through basic researchand international standardization of speech andacoustic communication—Would you tell us about the research you are currently conducting?
In 2022, I set a new research theme “research andstandardization of natural and highly functional
speech/acoustic communication technology,” andI’m researching technologies to (i) achieve highly
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Vol. 21 No. 9 Sept. 2023

functional immersive communication that supports
multipoint conferences that are natural to people andselectively conveys only the sounds people want tohear or convey to others and (ii) create a speech andacoustic communication environment in which thequality of experience (QoE) is naturally and automatically improved according to individuals and situations.
When people are having a face-to-face conversation, even in the presence of ambient noise, they
selectively hear the voice of the person they are6Front-line Researchers

Processing within the sending device (smartphone/3D glasses)
Semantic segmentation and context analysis

Context specified by the virtual space server
For conference calls- Size of virtual conference room
- Virtual placement of conference participants(over-ridable by receiver)

Processing within the receiving device
Context-dependent rendering

Separates semantic chunks of sound and generates metadata, such as
sound class, direction, and location in space, that describe therelationship between those chunks.

C = adult male

Key-note
separation

Mic. input

C = petSound
pickupC = child

Separatedsound and 3GPP IVAS
metadata
codec(sound class,direction,
Encoding
spatial extent,of soundsourcematerial andmovement
metadata
information,etc.)
Selection
Context specified by sender
For conference calls- Only my voice is to be heard- Do not send background noiseSound-space
Businessreconstruction
using 3GPP IVAS communication
Reconstruction
and playback of
the required
sounds(metadataassisted spatial
audio rendering)

Familycommunication

Context specified by the receiver
For conference calls- The voice of the president of the client company is placed in
the center at high volume.
- The voices of the president’s entourage are placed to theleft and right, and those of colleagues are placed at the rear.

C = sound class

Fig. 1. Example applications of semantic-segmentation technology to immersive communication.

talking to. When people are participating in remote
conferences at home, however, the microphone faithfully picks up ambient sounds that the speakers do notwant to be heard, and those sounds are played throughthe loudspeakers of the other participants. Conversely, when family members (such as parents and grandchildren) who live far apart are remotely communicating, these ambient sounds enhance the intimacy ofthe communication. In other words, in communication, we want to convey and hear certain sounds.
Certain communication methods are used forremote environments, and others are used for “real”(i.e., face-to-face) environments. The use of remoteenvironments was accelerated by the COVID-19 pandemic, but with the end of the pandemic, many situations that mix remote and real environments haveemerged. Therefore, developing communication
methods for such a hybrid environment is an issue.
We can address the above issues by selectively
communicating only the sounds we want to convey orhear in accordance with the purpose and situation. To
achieve such highly functional immersive communication, it is necessary to understand the semantic
structure of input acoustic signals and extract acoustic objects (i.e., semantic chunks of sound, including
metadata) by applying technologies for understanding the sound environment such as acoustic-event
detection and sound-source-direction estimation. The
key technology to meet this requirement is to automatically acquire representations for executing such
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extraction from data.
Reconstructing the extracted acoustic objects andapplying them to, for example, transmission and virtual-reality (VR) and augmented-reality (AR) playback is being investigated. For VR/AR communication, “semantic segmentation” is an important technology to separate acoustic objects from multiple
mixed sound inputs and output them with class andspatial information (Fig. 1). Since some use cases do
not necessarily require high quality or the extractionof all acoustic objects, highly functional immersive
communication is implemented by (i) estimating
QoE in accordance with the use case (by modelingthe sound-quality-evaluation criterion on the basis ofhuman-auditory perception) and (ii) automatically
improving and tuning the sound quality and acoustic
objects to be extracted to meet the criterion.
I believe that these technologies for highly functional immersive communication can be used for not
only conference calls but also remote medical care,monitoring the elderly, remote control of heavymachinery, and other use cases where sound is heard
remotely. With these use cases in mind, I’m aiming
for practical application of these technologies
through international standardization and othermeans.

7

Front-line Researchers—Before setting this new theme, what type of research
have you conducted thus far?
Since joining NTT in 1997, with the exception of aperiod of development work at an operating company
and research management, I have worked on speech/
acoustic signal processing, coding, and its international standardization. Recently, I have specialized inself-supervised learning and other representation
learning techniques and in applying these techniques
to understand sound environments such as acousticevent detection and anomalous-sound detection.
An achievement representing that work includes
the technical proposal and standardization of MPEG4 Audio Lossless Coding (ALS)*, a lossless coding
method for acoustic signals. MPEG-4 ALS is implemented in encoder equipment manufactured by NTT
Electronics and used for high-resolution music distribution and other applications. In 2018, in cooperation
with NTT DATA and other operating companies, we
practically applied our technology to detect anomalies from sounds made by machines and other equipment. This technology is being used to (i) monitor
vehicle abnormalities by analyzing train-runningsounds recorded on the ground and (ii) identify anddetect damage and deterioration of equipment infacilities such as power plants.
I have contributed to international standardization
through the following activities. At MPEG in ISO/
IEC, I helped standardize the MPEG archive format
in audio coding as a chair of the MPEG-Audio Ad
Hoc Group and helped standardize MPEG-4 ALS as
an editor. At IEC, I helped establish the IEC61937-10transmission standard as a project leader and editor,
and at the International Telecommunications Union Telecommunication Standardization Sector (ITU-T),
I served as an editor on the audio coding standard,
ITU-T Recommendation G.711.0. At the Internet
Engineering Task Force, I served as an editor on RFC
7655, which specifies payload formats in the Realtime Transport Protocol.
At the 3rd Generation Partnership Project (3GPP),an international standardization body for mobile
communications, I also contributed to the international standardization of Enhanced Voice Services(EVS), a high-quality audio-coding technology thatis now implemented in all smartphones and adopted
by NTT DOCOMO’s VoLTE HD+ (Voice over LongTerm Evolution High Definition+) service. I’m currently working on the international standardization of
IVAS (Codec for Immersive Voice and Audio Services), which aims to achieve high-quality multiNTT Technical Review

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point telephone services using audio-object codingthat enables immersive two-way communication(Fig. 2).
In 2020, I served as general chair of Detection andClassification of Acoustic Scenes and Events(DCASE), a major international conference onunderstanding sound environments, where our teamproposed a model for describing the sound on thebasis of the distance between language and sound andwon first place in the DCASE Challenge Task 6:
Automated Audio Captioning task.
Practical application of basic research results
through international standardization—You have been involved in a wide range of activities
from basic research to international standardization.
In this context, could you tell us what you value as a
researcher?
In my research, I find a research topic (technology)
with real-world applications in mind, carefully
observe the constraints and requirements, and createa reasonable hypothetical model by comprehensively
examining the observation results from physical, psychological, mathematical, and informational perspectives. By using this model, I devise the functions
necessary for practical use and the methods to implement them and make proposals to international standardization conferences and organizations toward thegoal of our technology being used in society. Thismodel can be created as a precise and complex modelor as simple and easy model in accordance with thesituation, so I find the appropriate model representation in consideration of accuracy and other requirements for practical use cases.
When considering the requirements from a practical standpoint, for example, in noise detection, I also
tried to change my way of thinking. In general, musicor voice is a target signal and background noise is an
unwanted noise. In anomalous-sound detection, however, it is necessary to construct a model by treating
strange noise made by machines as a target signal andnormal machine sounds as noise. In terms of how tomodel the phenomenon of interest, the basic idea is*

MPEG-4 ALS: A lossless compression method standardized aspart of MPEG-4 Audio by the Moving Picture Experts Group(MPEG) in International Organization for Standardization/International Electrotechnical Commission (ISO/IEC). It is a datacompression method with which the volume of data before compression and the volume of data that are compressed then decompressed can be completely equal.

8Front-line Researchers

Legend:Priority control

Best effort

Enables OTT and operators to collaborate to provide
immersive communication services

Mobile/fixed networks

Web conferencing

IOWN

Voi
ce

Transform
coding, mixing,
Voice depends on OTT.
re-encoding- Best effort- Inconsistent speech coding- Quality degradation due to re-encoding

Additional functions are provided
by each company.
- Video/documents- Sense of immersion

Extension
to IOWN
communication

Unified coding
protocol

Vo ic
e

IVAS*
(including
EVS)

Optical-fiber
phone

ce

- Total priority control withmobile-fixed coordination- High sound quality with noneed for re-encoding- Multipoint and multichannel
parallel-transmission coding

Voi

Priority
control but
independent

Voice

Voice uses priority control.
VoLTE*IVAS international standard + related protocols

IOWN: Innovative Optical and Wireless Network
OTT: over the top
VoLTE: voice over Long-Term Evolution

Fig. 2. Aim of 3GPP IVAS standardization at NTT.

the same as the technology used in lossless coding
and EVS.
As a corporate research institute, NTT Communication Science Laboratories is engaged in everythingfrom basic research to practical applications, and ourdesire is to advance research that is useful to society
and ultimately contribute to humanity in some formor another. We have therefore set themes that are at
the intersection of needs and new technologies or
seek to find that intersection. As basic researchers,
however, we must also be aware of competition withother researchers. Therefore, there is only so muchone person can do, so I believe it is important to focus
on what only we can do, rather than trying to do
everything by oneself. It is therefore important towork as a team with organic cooperation and divisionof roles or collaborate with outside parties.
—Is the world of international standardization established through the consensus of participants different
from that of basic research?
In the world of international standardization, being
useful to society is of paramount importance. Otherwise, there would be no point in establishing an international standard. Therefore, participants in international standardization will make proposals toward
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sions. In discussions, conflicts of opinion sometimes
arise; even so, the roles of the chairperson, rapporteur, and others, who are basically elected, are to
bring those in conflict together and increase the number of supporters to reach a consensus. To fulfill theseroles, they need to be trusted by the participants andhave broad and deep technical expertise in the field.
My subject technology is only a small part of theinternational standardization arena, but I still find it
frustrating when our technology is not adopted, so I
will make every effort to get it adopted. Even if ourtechnology is not adopted directly, I believe that demonstrating it as a competing technology leads to theadoption of easier-to-use and more valuable technology, thereby contributing to humankind.
As for research, each researcher has their own areaof expertise and phase of expertise within phasesfrom theme setting to practical application. Even if
the themes and goals of different researchers areclose, different approaches will result in different
time frames. I believe this time-frame difference is
one element of the competitiveness in research.
I have a position as both a researcher and contributor to international standardization; however, I am
engaged in research with the aim of making practicaluse of technology, so I am not conscious of each role
being a separate entity. As I mentioned earlier, I am
always aware of the intersection of needs and new9Front-line Researchers

technologies, so issues and requirements discussed ininternational standardization become needs, which inturn become research themes in terms of pursuing
new and basic technologies for satisfying thoseneeds. On the contrary, we may propose the new technology resulting from our research to internationalstandardization bodies, where discussions can lead tothe formation of new methods for applying that technology.
To cite a recent activity, I’ve been fostering a community at DCASE through the anomalous-sounddetection challenge that I am organizing with otherresearchers. Through this challenge, we haveincreased the number of researchers in the field of
anomalous-sound detection and have created a platform that enables us to refer to new technologies thatemerge from this challenge and eventually gain
insights that we can use in our business. Participantsin the community are also using this platform toadvance their research. Although this challenge differs from international standardization, I believe it
will greatly accelerate the process of making a technology useful to society.
Effectively communicating the value of research—Could you give a message for younger researchers?
In many cases, researchers research a topic that isof interest to them, which can be fun. Such research
can be undertaken by convincing those around you—sponsors, customers, partners, operating companies,
supervisors, colleagues, and rival researchers—of its
value. To get people to understand that value, youneed to show them evidence. It is necessary to explain
what you aim for, what you want to do, why it isimportant, and how you will solve the problem thenprovide evidence to support these elements. However,

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the people to whom this evidence should be presented—sponsors, customers, partners, operating companies, supervisors, colleagues, and rival researchers—
are not all experts, and some are not researchers orengineers. You should effectively communicate thevalue of your research so that people from various
walks of life will understand it. To this end, I believe
it is necessary to be aware of the environment surrounding your research.
In the field of basic research, however, disruptive
technology that is too advanced to keep up with cansuddenly emerge. In such cases, you should not be
distracted by what others say; instead, strive forward
on the path you believe in. If, as a result of yourresearch, you can demonstrate strong evidence thatno one can refute, those around you will eventually
be forced to understand. Of course, I think everyone
should make an effort to be understood whateveramazing technology you have developed.

Interviewee profile
Noboru Harada received a B.S. and M.S. fromthe Department of Computer Science andSystems Engineering from Kyushu Institute ofTechnology, Fukuoka, in 1995 and 1997 and later
received a Ph.D. from University of Tsukuba,
Ibaraki. Since joining NTT in 1997, he has been
researching lossless audio coding, high-efficiency coding of speech and audio, and their applications. He is an editor of ISO/ IEC 23000-6:2009Professional Archival Application Format, ISO/IEC 14496-5:2001/ Amd.10:2007 reference software MPEG-4 ALS and ITU-T G.711.0 and has
contributed to 3GPP EVS.

10

Rising Researchers

Transmission Technology for Spacedivision Multiplexing Supporting
Next-generation High-speed, Largecapacity Communications beyond
Existing Limits
Takashi Matsui
Distinguished Researcher, NTT AccessNetwork Service Systems Laboratories
Abstract

Recent years have seen remarkable developments in information and communications technology and a dramatic increase incommunications traffic. The capacity limit in existing opticalfiber supporting such communications is about 100 Tbit/s per
optical fiber, and it is predicted that transmission systems using
this optical fiber will reach this limit in due time. In this interview,
we talked with NTT Distinguished Researcher Takashi Matsui
about his research on solving this transmission capacity problem
by greatly expanding optical transmission capacity using “opticalfiber transmission line technology for space-division multiplexing.”
Keywords: optical fiber, space-division multiplexing, multi-petabit class

Optical fiber transmission line technology forspace-division multiplexing for achieving a
multi-petabit-class transmission infrastructure—Dr. Matsui, what exactly is “optical fiber transmission line technology for space-division multiplexing”
for solving the transmission capacity problem?
Optical fiber transmission line technology forspace-division multiplexing (SDM) prepares multiple light paths within optical fiber to perform communications and achieves far more transmission
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Vol. 21 No. 9 Sept. 2023

capacity than existing technologies. In recent years,
the usage scenarios of information and communications technology (ICT) have become quite diverse
producing a sharp rise in the demand for transmission
capacity. For example, the core network that bundles
and transmits communications signals over long distances between prefectures in Japan currently implements an optical transmission system having a transmission capacity of 16 Tbit/s per optical fiber, which
represents an increase of about 1000 times over thelast 20 years. The capacity limit of optical fiber now
in common use is predicted to be about 100 Tbit/s per
11

Rising Researchers

Current optical fiber(single-mode single-core)Multi-mode multi-coreSingle-mode multi-core

Extends the number of spatial channels
by number of cores × number of modes
Each core can be used independently
enabling bidirectional, point-to-multipoint,
and other types of operation within one
fiberStandard-cladding-diameter multi-core fiber technology

250±
15 µm

Number of
spatialchannels

Manufacturability equivalent
to current optical fiber
Excellent upgradability due tocompatibility with standard
technology

125±
0.7 µm1~4

10 or more

Fig. 1. Evolution of optical fiber technology.

optical fiber, so we can expect the current opticaltransmission system to reach its limit around 2030
due to the rapidly rising demand for communications.
The solution to this problem in next-generationtransmission capacity is SDM optical fiber transmission line technology. The mainstream form of opticalfiber used in today’s optical transmission system issingle-mode fiber that transmits signals through only
one path per optical fiber. In contrast, SDM opticalfiber transmission line technology transmits signals
through multiple, independent paths per optical fiber.
Since increasing the number of paths by n times
increases transmission capacity by approximately ntimes, it becomes possible to dramatically expand
transmission capacity beyond comparison with existing technology.
To increase the number of optical paths in a single
optical fiber, we research SDM optical fiber transmission line technology mainly from two perspectives:
the part of the fiber that passes light called a “core”
and the way in which light propagates through a corecalled a “mode.” There are three specific approaches
here: multi-core fiber that incorporates multiple
cores, multi-mode fiber that sets multiple modes in asingle core, and multi-mode multi-core fiber thatcombines the above two technologies. In the case ofmulti-core fiber that is as thin as current optical fiber,
the maximum number of single-mode cores is four.
On the other hand, multi-mode multi-core fiber
enables light to propagate in multiple spatial modes
per core, which makes for excellent extendibility. As
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an example, establishing three modes within each offour cores means that light can propagate through 3 ×
4 = 12 paths (spatial channels), which opens up the
possibility of expanding transmission capacity by asignificant amount. In addition, combining this feature with technology for expanding wavelength
bands in optical fiber is expected to greatly expand
transmission capacity beyond what ever could beachieved by conventional technologies (Fig. 1).
—What are some of the difficulties that have to be
overcome in SDM optical fiber transmission line
technology?
In multi-core fiber having multiple cores in a single
optical fiber, a phenomenon called “crosstalk” arises
in which light leaking into a neighboring core createsinterference. This crosstalk can significantly reducetransmission capacity to an extent that prevents transmission capacity to be increased by n times by
increasing the number of paths by n times. At NTT,
we are working to solve this problem by attempting
to fit as many cores as possible into a single opticalfiber while making the inter-core distance large
enough to prevent the generation of crosstalk. Of
course, making the diameter of the optical fiber larger
would enable the number of cores to be increased.
However, thicker optical fiber creates problems in
relation to physical properties such as making it hard
to bend the fiber when laying and making it difficult
to handle the fiber cable overall. On top of this,12

Rising Researchers

making the diameter of optical fiber larger meansincreasing the amount of glass material used, which
can greatly degrade the manufacturability of opticalfiber. When setting out to deploy optical fiber in
actual facilities, these problems in physical properties
and ease-of-handling and in manufacturing cost takeon great importance. So researching without taking
these problems into consideration can lead to a resultin which no one would be able to use the optical fiber.
It is for this reason that searching for an optimal number of cores while maintaining the conventional
diameter of optical fiber has become a key researchissue.
In parallel with this research, we are also researching the expansion of wavelength bands in opticalfiber. At present, systems are configured with opticalfiber in which signals are packed into a region limited
to a bandwidth of about 35 nm called the C-band in
the 1.5-μm range. If this wavelength band can be
expanded so that a wide range of wavelengths can beused, a quantum leap in transmission capacity should
become possible. We are therefore conducting
research with the aim of expanding the wavelengthband to the 1.6-μm band, for example, to support theneed for greater transmission capacity with NTT’svision of the Innovative Optical and Wireless Network (IOWN) in mind. In the design of optical fiber,
the task is to find a wavelength band in which sufficient transmission quality can be obtained by controlling changes in the refractive index and optical characteristics of optical fiber. However, two key technical problems in SDM optical fiber are “crosstalkincreases when expanding the upper wavelength limit(to longer wavelengths)” and “light can easily leakwhen expanding the lower wavelength limit (toshorter wavelengths).” In optical-fiber structures up
to now, shortening the lower wavelength limit andlengthening the upper wavelength limit have had
tradeoffs, so we are exploring new optical-fiber structures and manufacturing methods that can significantly increase transmission capacity while searchingout wavelength bands that can be used.
—What have been some of the achievements of SDM
optical fiber transmission line technology to date?
As one achievement of SDM optical fiber transmission line technology, our research group successfully
performed a relay transmission experiment exceeding a transmission capacity of 100 Tbit/s per opticalfiber in cooperation with industry, academia, andgovernment in 2017. We did this by using a transmisNTT Technical Review

Vol. 21 No. 9 Sept. 2023

sion line that interconnected 4-core multi-core fibers
fabricated by multiple vendors. We have also been
researching the number of cores and modes that can
fit within a certain fiber thickness for which the optical fiber breakage rate can be sufficiently tolerated. In
2018, we demonstrated a 10-mode, 12-core multimode multi-core fiber thereby achieving the world’s
highest number of spatial channels at 120.
In research reports on SDM optical fiber up to now,
extremely diversified structures have been proposedin terms of the number of cores, thickness of the optical fiber, and other parameters. However, when actually making optical fiber into a product and using it incommunications facilities, connectivity between
optical fibers and compatibility with other devices
and facilities must be ensured. For this reason, NTT
took the worldwide lead in proposing that the thickness of optical fiber be maintained at 0.125 mm asused by existing single/multi-mode fiber and thatfour cores are optimal in transmission by multi-core
fiber.
These research efforts have progressed through collaboration with many experts and individuals fromthe NTT Group. When arriving at the stage of installing optical fiber, a variety of technologies that areneeded to configure a total optical communications
system must be studied in addition to connectivity,
such as input/output methods, transmission-equipment and system configuration, and operation methods. Our research has been making good progress byreceiving feedback from many people.
In view of a 125-fold increase in transmission
capacity as a target of the All-Photonics Network inNTT’s IOWN vision, we are aiming for a transmission capacity potential of more than 10 times in an
optical fiber transmission line as our research target
going forward. To achieve this target, the first step inour research plan for SDM optical fiber transmission
line technology is to focus our attention on establishing technology for 4-core multi-core fiber having
high affinity with existing optical technology. Additionally, while using this 4-core multi-core fiber technology as a basis to work from, we will explore
methods of establishing technology that can extend
the number of spatial channels in one direction to 10
or more and thereby achieve a transmission capacity
potential of more than 10 times in an optical fibertransmission line.
Moreover, taking into account present capacity
demands, it is predicted that the demand for transmission capacity will increase to the multi-petabit
class from 2040 on. We therefore want to work on
13

Rising Researchers

Transmission capacity (bit/s per fiber)

10P
Terrestrial
Submarine
1P

100T

Multi-petabit
class
Target of IOWN

Existing system(single-mode fiber)
125±
0.7 µm

10T

SDM technology

1T

0.1T
2000

2010

2020

2030

2040

2050

Fig. 2. Research targets toward a new transmission infrastructure.

establishing technology that can also support the
future beyond IOWN. Furthermore, in addition tohigh-density SDM optical fiber starting with multimode multi-core fiber, we will also work on technology for controlling wavelength characteristics. Our
aim here is to establish new optical fiber transmission
technology that can achieve transmission capacity 50
times that of current levels and support transmission
capacity of the multi-petabit class (Fig. 2).
Placing importance on the user’s point ofview—flexible thinking builds a new future—What way of thinking should be valued in research?
In my many years of research, I have often witnessed the appearance of optical fiber and devices
based on totally new concepts different from those of

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the past. At the research stage, this can be quite exciting, but a pitfall here is that a new fiber or device may
turn out to be useless when it comes time for actual
implementation. Of course, when you are pursuing
only the research immediately in front of you, novalue is being created. To some extent, I think it’svery important to strike a balance between an awareness of how research is to be used in the future andtaking up the challenge of new, cutting-edge research,and then set and prioritize themes. No matter how
interesting a certain research theme may be, I believe
it is meaningless if it comes to be used nowhere in theend. I myself have experienced such a failure any
number of times, and to avoid making the same mistake again, I conduct my research while listening todiverse viewpoints and exchanging opinions withexperts in other organizations and fields and manufacturers too. In this way, I can expand my field ofvision.
In fact, NTT Access Network Service Systems
Laboratories that I belong to is in charge of all sortsof technologies that are needed in the network to connect customers with central offices. It deals with avery broad range of technical fields from civil-engineering facilities, optical facilities, and wirelessfacilities to operations and services. Because it has
facilities throughout Japan, it has high technical competence and a great ability to make judgments on thespecifications, construction, and operation of thosefacilities all the way from research and development
to implementation and operation. I believe that this isa major strength of NTT Access Network Service
14

Rising Researchers

Systems Laboratories. In addition, I feel that the ability to develop and implement technologies while
fortifying our ties with NTT Group companies anddiscussing their needs is very reassuring for researchers. The achievements that have come about throughthe efforts of senior researchers are also encouraging.
Moreover, I have many opportunities to hear what
people in standardization organizations and academic
societies outside of NTT have to say, and I can conduct my research while exchanging opinions with awide range of people. Interacting with people in avariety of situations is truly a blessing. I believe that
this sort of environment is very important for achieving success in research.
—Dr. Matsui, could you leave us with a message forresearchers, students, and business partners?
Today, technology is progressing, and we are entering an era in which many people, myself included,
can feel its benefits. Technology will continue to
evolve: communications in our daily lives will
become even more convenient through wireless technologies, and cutting-edge services and social innovations will be driven by virtual reality, artificial
intelligence, and other types of advanced software.
From here on, however, optical transmission facilities will become indispensable to support such highspeed communications and new social developments.
Yet, in recent years, it has become difficult to focus
on technologies related to the communications infrastructure as they tend to be hidden by software-based
technical fields in the digital space. So the communications infrastructure is perhaps a low-profile field,
but if new technologies in this field can be released to
the world, I think they would have great potential indriving dramatic changes in existing industries andtoday’s society. Going forward, I myself would liketo promote top-level research results throughout theworld and contribute to the development of new optical communications facilities including the standard-

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ization of these results in a form that can provide forpractical deployment. In this endeavor, I look forward to everyone’s support.
Additionally, while I hope that this will be thedesire of people involved in the research of opticalcommunications from here on, there is still muchroom left for discussion in how this field should continue to develop and in what way new technologies
should be pursued. If a flexible way of thinking canbe adopted as in the merging of our technologies withtechnologies in other fields, I believe that the entire
optical communications field can be energized andthat the future of the communications infrastructure
can be made bright indeed. To those who can sow theseeds of such flexible thinking and to readers who
find this article interesting, I would say, “Let’s work
together to build a new future for optical communications.”

Interviewee profile
Takashi Matsui received his M.E. in electronicengineering from Hokkaido University in 2003
and entered NTT in the same year. He received
his Ph.D. in electronic engineering from Hokkaido
University in 2008. He has been an NTT distinguished researcher since 2022. He is engaged in
the research of optical fiber transmission line
technology for space-division multiplexing
toward a dramatic expansion of space and wavelength resources. He is a recipient of the Japanese
Ministry of Economy, Trade and Industry (METI)International Standardization Contributor Awardin 2021, SPIE Photonics West 2021 Best TechnicalPaper Award, and OECC/PS 2019 Best Paper
Award among other awards. He has been a visiting professor at the College of Engineering,
Ibaraki University since 2022.

15

Feature Articles: Launch of APN IOWN1.0 Service

APN Service-provision Activities
Junichiro Saito and Yukiko Chaki
Abstract

In March 2023, NTT EAST and NTT WEST launched APN IOWN1.0, the first-version service of the
All-Photonics Network (APN), which is one of the major technology areas that comprise the Innovative
Optical and Wireless Network (IOWN). APN IOWN1.0 provides ultra-low latency and enables the visualization and adjustment of latency with microsecond granularity. This article describes the position of
the newly introduced APN service within the IOWN concept and the value the service provides. It alsopresents typical use cases and an overview of the service.
Keywords: APN IOWN1.0, ultra-low latency, visualization and adjustment of latency

1. Introduction
On March 16, 2023, NTT EAST and NTT WEST
launched APN IOWN1.0, the first-version service of
the All-Photonics Network (APN) of the Innovative
Optical and Wireless Network (IOWN) [1].
The APN is one of the major technology areas comprising IOWN. It implements photonics-based technology everywhere from terminals to the network,
thereby providing end-to-end optical wavelength
paths. Its aim is to achieve unparalleled low-powerconsumption, high-quality, high-capacity, and lowlatency transmission.
With this capability, the APN will address network
issues, such as ever-growing traffic volume, network
complexity, and latency due to congestion. It will also
address energy-consumption issues, such as increases
in power consumption at datacenters. The APN will
make it possible to provide customers with new experiences and value, such as the fusion of real andonline activities that will be required in response tochanging lifestyles.
Although the target year for implementing IOWN
is 2030, we decided that the value of ultra-low latency can be provided by combining technologies andproducts currently available. Thus, we studied thepossibility of launching the APN service in March
2023, ahead of 2030. The intention was that the early
introduction of the APN service would enable us towork with customers to accelerate the creation of newuse cases and new value.
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The efforts to implement APN IOWN1.0 were led
by NTT EAST and NTT WEST in collaboration with
the Innovative Technology Office under the NTT
Technology Planning Department, whose mission is
to commercialize IOWN-related technologies, theIOWN Development Office under the NTT Researchand Development Planning Department, which is
responsible for promoting research and developmentof IOWN-related technologies, and NTT laboratories(NTT IOWN Product Design Center, NTT Network
Innovation Laboratories, and NTT Network Innovation Center), which are researching and developing
APN-related technologies and products (see Table 1).
2. APN IOWN1.0 provides ultra-low latency
Of the three performance targets of the APN [2],APN IOWN1.0 offers the value of ultra-low latency
with end-to-end latency being 1/200*1 that of the conventional network. It also features a commercial
implementation of “OTN Anywhere,” an opticaltransport network (OTN) terminal device developed
by NTT laboratories that visualizes and adjusts
latency with microsecond granularity.
The performance targets of the APN for 2030 are as
follows.
(1)	100-times higher power efficiency: We aim toachieve low power consumption by implementing technology that transmits signals all*1 End-to-end latency being 1/200: Target latency for intra-prefecture video traffic that does not require compression.

16

Feature Articles

Table 1. Organizations involved in the implementation of APN IOWN1.0.
Organization

Role

NTT EAST/NTT WEST

Install equipment and provide service

NTT Technology Planning Department

Promote commercialization of IOWN technology

NTT Research and Development Planning Department

Promote research and development of IOWN technology

NTT IOWN Product Design Center

Promote the implementation of products that adopt IOWN technology

NTT Network Innovation Laboratories

Undertake APN-related research and development

NTT Network Innovation Center

Develop APN-related products

the way through the network to the terminal in
optical form as well as by implementing technology of photonics-electronics convergence.
(2)	125-times higher transmission capacity: This
will be achieved through the use of new multicore optical fibers, implementation of highcapacity transceivers, and adoption of highcapacity optical-transmission-system technology.
(3)	End-to-end latency being 1/200 that of theconventional network: We seek to achieveultra-low latency by transmitting informationin units of wavelengths, eliminating the needfor encoding and compression.
Take video transmission as an example. In a current
mainstream Internet protocol (IP) network, it is general practice for a video captured with a camera to be
encoded and compressed for transmission over the IP
network with the data being decompressed anddecoded at the destination before the video is displayed on a monitor. In the APN, however, the OTN*2
protocol is used for high-speed layer 1 communication paths, making optical-wavelength spans end-toend paths. This eliminates packet queuing at routersand switches in the paths, enabling jitter-free communication with ultra-low latency. Since the APN has
high capacity, video can be transmitted without
encoding or compression. Thus, the APN reduces
latency currently caused by encoding and compression and eliminates jitter that is currently produced byfluctuations in packet forwarding. By using lowlatency cameras and monitors, we can minimize
latency throughout the entire system.
We provide the capability to visualize and adjust
latency with microsecond granularity by connecting
OTN Anywhere (Fig. 1). This device makes it possible to equalize delays across different locations. This
capability is effective and valuable for use cases that
require fair timing between different locations, suchas e-sports.
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3. APN IOWN1.0 use cases
The ultra-low latency provided by APN IOWN1.0
is beneficial not only for e-sports but also for a variety of use cases not achievable with conventional
networks, such as the remote operation of surgicalrobots in areas where doctors are in short supply,
remote operation of devices in vast factories and offacilities located high above ground, and remote production in the broadcasting industry through realtime video transmission.
The availability of a network with high performance means that applications in various businessfields that have been conventionally processed onpremises can be processed over the network. This
will help produce solutions that overturn the conventional way of business (Fig. 2).
A typical benefit of ultra-low latency is the ability
to perform precise operations and tasks even from a
distance (Fig. 3). Typical use cases that demonstrate
this ability are described below.
3.1 Telemedicine using surgical-support robots
There are concerns over the shortage of surgeons inrural areas and too great a concentration of medical
specialists and supervising doctors in urban areas.
These concerns have given rise to expectations fortelemedicine. Connecting a surgical robot with aremote operator via the APN makes informationtransmission between them fast and jitter free, facilitating high-quality remote surgical support throughstable robot teleoperation. It is also important to provide an environment in which medical personnel at aremote location can feel as if they are in the sameroom as the patient. Bi-directional communication
over the APN enables medical personnel to conduct*2 OTN: A communication standard for optical transmission networks specified by ITU-T (International Telecommunication
Union - Telecommunication Standardization Sector), an international standardization organization.

17

Feature Articles

User site A

Local office A

Transit office

Local office B

User site B

User site A

Local office A

Transit office

Local office B

User site B

Statusquo

APN

Electrical signal
Optical signal

Optical wavelength path

Bandwidth*

Fig. 1. APN provides ultra-low latency.

Real-time video distribution
Improved visual recognition at stadiums, etc.
of images from surveillance
RAN-aware content optimization
camerasMulti-access management
Surveillance camera video
analysis
Distributed
caching ofSurveillance using network cameras
content and DNS
Fast download for AR/VR
devicesSmart cities/buildings
Fast upload of large files

Video
Efficient high-capacity communication
Transportation
M2M
VR/AR
Efficient communication

Improvement of user experience in games using AR and VR

AR applications
Local breakout
AR content distribution
Video delivery throughput optimization Application-aware
performance optimization
Remote rendering using GPU server
Abnormal sound detection
Stream optimization for video analysis
Remote operation support
Presentation of products based on customer
attributes in retail stores
Closed-loop control
Video analysis
Virtual network services
Smart
Formation and coordinated control
Automatic roadmuseum Videoconferencing usingof robots/drones/vehicles
telecombuildingEC
surface map creation
Edge computing
Smart factory
Robot control
Multipoint
accessdeviceinside aircraft
through a holo-lensLocation tracking ofTraffic flow control and automated driving
Performance improvement of
Tactilemobile devices, etc.
Preventive maintenance IT services in the retail industry communication
Support for collision avoidanceof facilities and equipment
for vehicles and robots
Connected car (safety support)
Ultra-large data storage service utilizing
Rendering ofConnected car (data analysis)
Ship
IoT
Streamoptimization
regional dispersion of telecom buildings**
VR imagesfor video analysis
Operational support and maintenanceservices for railroad

Cloud
A few s*The bandwidth of each application is determined on the basis of the physicalcommunication speeds required for the terminal and access network and thebackhaul bandwidth, and is calculated by adding up the communication speedof each terminal multiplied by the number of terminals accessing the edge site.
**The required bandwidth is narrow because storage units are physically delivered.
AR: augmented reality
DNS: domain name system
EC: edge computing
GPU: graphics processing unit

Edge
A few 10 ms

On-premiseLess thana few ms

Low latency

IT: information technology
M2M: machine to machine
RAN: radio access network
VR: virtual reality

Fig. 2. Areas that are expected to benefit from low latency.

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18

Feature Articles

Conventional IP/Ethernet

IOWN APN

Remote operation is difficult due tothe levels of latency and jitterin communication.

Precise remote operation is possible
because latency and jittercan be minimized.

Fig. 3. Image of a use case that takes advantage of ultra-low latency.

surgery while viewing high-resolution images, suchas 8K video, of the patient’s condition, operating
room, and other operational conditions. By supporting telemedicine, we are aiming for further development of regional medical care.

ing*3 and applying the APN to mobile fronthaul torapidly expand the service area of Beyond fifth-generation mobile-communication system (5G)/6G.

3.2 Smart factories
The low-latency, jitter-free APN makes remote
operation possible for a wide range of tasks and maintenance work in vast environments, such as chemicalplants and precision-equipment manufacturing
plants. Remote fine operations, such as checking
equipment and fine-tuning valves located high above
ground or in explosion-proof areas, enable skilled
personnel to gather in a room in factories and safely
perform high-risk tasks. Implementing Internet ofThings (IoT) in machines and systems at multiple
locations and connecting them via the APN makes it
possible to automate manufacturing lines and enables
automated remote inspection of products before shipment.

The APN IOWN1.0 service achieves high-speed,
high-capacity, low-latency, and jitter-free communication by providing dedicated optical wavelength inall sections of the network and using the optical transport unit 4 (OTU4)*2, which accommodates multiple
optical transmission networks, at APN interfaces.
The combined use of OTN Anywhere, which is an
APN terminal device, makes it possible to visualize
and adjust latency (Fig. 4).
(1) Features of APN IOWN1.0•	High speed, high capacity: Dedicated point-topoint 100-Gbit/s paths.
•	Low latency, jitter free: Latency 1/200 that ofconventional networks, no jitter*4, and no impact
from other users’ traffic thanks to the use of a
dedicated optical wavelength for each path.
(2) Features of terminal device, OTN Anywhere•	Conversion of information format: The device
receives 10-GbE or 100-GbE signals from customer devices, converts them to OTU4, andoutputs them.
•	Visualization and adjustment of latency: The
device visualizes latency by outputting the resultsof measurements at certain points as an OTN Anywhere log, which can be used to adjust latency
with microsecond granularity (8 μs to 20 ms).

3.3 Remote television production
The broadcasting industry is focusing on remotetelevision (TV) production, a new method of live
program production, by which video captured at an
event site is transmitted to a program-production site
in real time. The high-capacity, low-latency APN
enables uncompressed transmission of video between
an event site and program-production site. Conventionally, production equipment needs to be brought tothe event site, and a program is produced on-site anddistributed to broadcast stations. Remote TV production reduces the need to bring equipment and personnel to the event site.
Beyond the examples introduced above, we will
endeavor to expand applicable use cases by combining the APN with other IOWN technologies and further evolving the APN. Such attempts include connecting datacenters with the high-capacity and lowlatency APN to enable optical disaggregated computNTT Technical Review

Vol. 21 No. 9 Sept. 2023

4. Overview of APN IOWN1.0*3 Optical disaggregated computing: In contrast to the conventional
server-oriented concept in which computers are connected via a
network, this concept takes advantage of the transmission characteristics of light by using optical fibers to directly connect computer resources, such as central processing units and memory
units, and treats them as a single computer on a datacenter scale.
*4 Latency 1/200 that of conventional networks, no jitter: Time division multiplexing (distinguishing multiple traffic by fixing thetime of transmission) is used to reduce traffic-dependent latency
and packet loss.

19

Event site, etc.

Customer devices

High-speed,
broadband-accessservicecomplying with OTU4standard

Terminal device (OTN Anywhere)

APN IOWN1.0

Terminating device

Terminating device

Remote production
site, etc.

Customer devices

Satellite site

Terminal device (OTN Anywhere)

Feature Articles

Fig. 4. Overview of APN IOWN1.0 service.

5. Conclusion
We launched APN IOWN1.0 as the first service
offering of IOWN. We expect that this early provisionof the APN will accelerate the creation of new services in collaboration with external partners as wellas the creation of new use cases and value for customers. We will continue to enhance the unique featuresof the APN, such as low power consumption enabledby photonics-electronics convergence technology
and high-quality, high-capacity transmission that

Junichiro Saito

Senior Manager, Innovative Technology
Office, Technology Planning, NTT Corporation.
Joining NTT EAST in 2005, he worked as a
network planner for regional networks. He wasinvolved in Next Generation Network (NGN)
operations from 2007. He was then engaged in
the launch of an NGN security task and enhancement in-house systems security until 2021. In his
current position, he has been promoting theimplementation of services actualizing the
IOWN concept.

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Vol. 21 No. 9 Sept. 2023

uses high-capacity optical-transmission-system technology on the basis of new optical fibers such as
multi-core fibers.
References
[1]

[2]

Press releases issued by NTT EAST and NTT WEST on Mar. 2, 2023
(in Japanese),https://www.ntt-east.co.jp/release/detail/20230302_01.html
https://www.ntt-west.co.jp/news/2303/230302a.html
Website of NTT R&D, IOWN, https://www.rd.ntt/e/iown/0002.html

Yukiko Chaki

Senior Manager, Innovative Technology
Office, Technology Planning, NTT Corporation.
Joining NTT WEST in 2007, she worked as a
network engineer, mainly formulating the strategy for network enhancement and performing
network operations and maintenance. In her current position, which she has held since 2022, she
has been promoting the commercial implementation of IOWN aimed at creating new businesses
that take advantage of IOWN technologies.

20Feature Articles: Launch of APN IOWN1.0 Service

Road to IOWN at NTT EAST
Takahiro Igarashi and Yuta Takino
Abstract

As the first commercial service of the Innovative Optical and Wireless Network (IOWN), NTT EAST
launched the All-Photonics Network (APN) IOWN1.0 service on March 16, 2023. In this article, we
introduce our demonstration efforts in taking advantage of low latency, use cases, and future prospectsof APN IOWN1.0.
Keywords: IOWN, All-Photonics Network, low latency

1. Significance of NTT EAST’s IOWN initiative
The NTT EAST Group aims to become a social
innovation company that supports the future of
regional communities for building a regional circularsociety. A regional circular society means expanding
the distinctive culture and diversity of the region
through information and communication technology
and digital technology, completing transportation
within the region, producing and consuming energy
locally, and distributing data regionally. By promoting such a society, the population, economic activities, and data that are concentrated in urban cities
would be dispersed across the region. As a result, we
can create new industries and employment locally.
The NTT EAST Group promotes the REIWA Project[1] to achieve this society. This is a project thatmaximizes the use of assets (buildings, equipment,etc.) owned by the NTT EAST Group in the region tosolve the problems of regional customers.
We believe that the Innovative Optical and Wireless
Network (IOWN) will drive our REIWA Project further. Interconnecting the regional edge clouds withthe low-latency and high-capacity All-Photonics Network (APN) enables a seamless ecosystem. By
implementing this system in society, we aim to build
a sustainable community.
2. Demonstration efforts
The NTT EAST Group conducted a demonstrationof a remote concert that used the low latency andlarge capacity of the APN, which is a technical comNTT Technical Review

Vol. 21 No. 9 Sept. 2023

ponent of IOWN. Due to the changes in society by the
spread of COVID-19, our psychological hurdles toremote communication have been lowered, and newstyles of co-creation and appreciation of music, suchas online streaming of concerts and remote lessons,are expanding. However, low-latency interactive
communication, which has been considered difficult
with conventional Internet-based networks, is necessary for remote concerts (Fig. 1). We aimed to resolve
this problem by incorporating low-latency videoprocessing technology and low-latency transmission
technology, which are elemental technologies of theAPN.
We first held a remote concert in March 2022 [2] byconnecting Bunkamura Orchard Hall (Shibuya-ku,
Tokyo) and NTT Inter Communication Center (Shinjuku-ku, Tokyo). This was the first case of a remoteconcert with APN-related technology in Japan.
Through the concert, we verified that even professional musicians could perform a remote concert
stress-free by reducing communication delay with theuse of the low-latency video-processing and the lowlatency transmission technologies.
We then held another remote concert that createdmore unity between two venues by connecting Tokyo
Opera City (Shinjuku-ku, Tokyo) and Dalton Tokyo
Junior & Senior High School (Chofu-shi, Tokyo) in
November 2022 [3]. The performances of the encore
program “Radetzky March” by the orchestra inTokyo Opera City and by the snare drum player in
Dalton Tokyo Junior & Senior High School weretransmitted bi-directionally to establish a remote performance. By bi-directionally transmitting the21

Feature Articles

Low-latency
video-processing
technology
Low-latencytransmission technology

Venue A

Venue B
Music/
Video

Music/
Video

Music/
Video

Music/
Video

Fig. 1. Remote concert (two venues).

clapping of the audience at both venues along withthe music with low latency, we achieved a new musicco-creation and appreciation experience in which theaudience felt as if they were in the same place eventhough these venues were about 10 km away.
The third demonstration was a multipoint andlong-distance concert [4] held in February 2023 byconnecting four locations, Tokyo, Osaka, Kanagawa,and Chiba. The Tokyo and Osaka venues had performers and audiences, the Kanagawa venue had
performers, and the Chiba venue had an audience. We
could provide an interactive musical experienceamong these locations. We also verified the feasibility of the network configuration for interconnecting
multi-vendor devices in accordance with the standard
specifications (Fig. 2).
Through these demonstrations, we confirmed thepossibility of holding a new style of remote concert
with a sense of unity among distant venues. In the
future, we will use the data and knowledge obtained
through these demonstrations to create new businesses for music performances, events, education,etc. as one of the new co-creation and appreciation
models in the field of culture and art.
3. Efforts to create use cases of APN IOWN1.0
NTT EAST launched the APN IOWN1.0 service on
March 16, 2023 as the first service of IOWN initiaNTT Technical Review

Vol. 21 No. 9 Sept. 2023

tive. APN IOWN1.0 can provide low-latency communication without fluctuations. In addition, APN
IOWN1.0 enables unprecedented delay visualization
and adjustment functions by being combined withterminal device called “OTN (optical transport network) Anywhere.”
Since these functions are effective for e-sports andreal-time communication with music and video, an
event sponsored by NTTe-Sports was held as a service release event for APN IOWN1.0 [5]. Response
speed has a large impact on winning or losing in
e-sports. Therefore, the play environment must be
precisely prepared. In fact, there are many players
who have postponed or hesitated to participate inonline tournaments due to concerns about the playenvironment such as transmission delays. In thisevent, APN IOWN1.0 was used to connect Miyashita
Park (Shibuya-ku, Tokyo: Miyashita) and eXeFelid
Akiba (Chiyoda-ku, Tokyo: Akiba) to hold an
e-sports exhibition match. No personal computer(PC) was installed on the Miyashita side, and players
remotely controlled the Akiba side PC via APN
IOWN1.0. The PC on the Akiba side was configured
to add the same amount of delay as the transmission
delay between Miyashita and Akiba (Fig. 3). As aresult, we achieved a play environment with no difference in delay between the Miyashita-side andAkiba-side players.
In terms of real-time communication with music
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Feature Articles

Osaka

Tokyo
Music/
Video

Music/
Video

Music/
Video

Music/
Video

Chiba

Kanagawa

Low-latency
video-processing
technology
Low-latencytransmission technology

Video of performers
at 3 venues

Tokyo

Tokyo-Osaka-Kanagawa session (Osaka venue)

Fig. 2. Remote concert connecting four venues.

and video, we demonstrated remote dance lessons.
NTTe-Sports is focusing on these activities because
they believe the demand of these remote lessons ishigh in regional revitalization and the Japanese government policy on transferring the operation ofschool club activities from schools to the local communities. A dance coach in Akiba instructed students
in Miyashita remotely with the background music
played at Akiba studio. We confirmed whether the
students in Miyashita could perform the lesson without any problems.
The e-sports players, dance coach, and students
who participated in these events said that they felt no
discomfort and could play and dance as if they werein the same place. We will use APN IOWN1.0 for
NTT Technical Review

Vol. 21 No. 9 Sept. 2023

e-sports competitions at multiple sites in urban andrural areas and for remote instruction such as arts andsports.
4. Efforts toward expansion of use cases andfuture prospects
We will promote the IOWN initiative through further expansion of use cases of APN IOWN1.0. For
example, the APN can be used in remote productions,in which operators in a remote location can switch oredit video sources when sending real-time video datafrom a venue such as a stadium (Fig. 4). The dataamount of the video source is generally so huge that
it is necessary to compress and convert the video data
23

Feature Articles

Latency measurement

IOWN
APN

OTN
DP AnywhereUSB

PC (1)

OTN
AnywhereUSB

PC (2)

Player (3)Miyashita

Akiba

DP

Latency measurement

PC (3)DP
OTN
Anywhere

Player (1)USB
DP
Player (2)USB

DP: DisplayPort
USB: Universal Serial Bus

Fig. 3. Structure between Miyashita and Akiba.

Stadium

Video-editing baseVideo signal

No compression/
decoding
Real-time
high-definition
video transmission

Fig. 4. APN utilization for remote production.

at the venue for transmission and decode them at thevideo-editing base. However, since the APN canresolve such a problem, we can transmit high-quality
images in real time without compressing or decoding
the data.
By connecting small and medium-sized datacenterswith the APN, they can be operated like one datacenNTT Technical Review

Vol. 21 No. 9 Sept. 2023

ter. With the APN, we can contribute to the decentralization of datacenters by reducing land use and electricity. Furthermore, the APN has the potential to be
applied to remote precision-machine operations bytaking advantage of the APN’s low-latency andzero-fluctuation characteristics, which also leads tolocal energy production and consumption.
24

Feature Articles

These are just a few examples, and we believe that
there are still more value of APN IOWN1.0 that weare not yet aware of. With this service release as anopportunity, we will expand the use cases with ourcustomers.
References[1]

REIWA Project (in Japanese), https://business.ntt-east.co.jp/content/
reiwa/

Takahiro Igarashi

Chief, Corporate Strategy Planning Department, NTT EAST Corporation.
He received a B.E. in mechanical engineeringfrom Keio University, Kanagawa, in 2013 andjoined NTT EAST the same year. He worked asa system engineer for 7 years. From 2020 to2022, he belonged to the General Affairs andHuman Resources Department.

NTT Technical Review

Vol. 21 No. 9 Sept. 2023

[2]
[3]
[4]
[5]

Press release issued by NTT EAST and NTT ArtTechnology on Mar.
24, 2022 (in Japanese), https://www.ntt-east.co.jp/release/detail/20220324_02.html
Press release issued by NTT EAST and NTT ArtTechnology on Nov.
7, 2022 (in Japanese), https://www.ntt-east.co.jp/release/detail/20221107_01.html
Press release issued by NTT EAST and NTT ArtTechnology on Dec.
22, 2022 (in Japanese), https://www.ntt-east.co.jp/release/detail/20221222_01.html
Press release issued by NTTe-Sports on Mar. 2, 2023 (in Japanese),https://www.ntte-sports.co.jp/newsrelease_20230302.html

Yuta Takino

Associate Manager, Corporate Strategy Planning Department, NTT EAST Corporation.
He received a B.E. and M.E. from the Tokyo
Institute of Technology in 2009 and 2011. In
2011, he joined NTT EAST and has been working as a network engineer.

25

Feature Articles: Launch of APN IOWN1.0 Service

NTT WEST’s Efforts in Providing
APN Services
Atsushi Ota, Masayuki Nishiki, Hideaki Kimura,
Kenji Matsumoto, Katsuhiro Tanabe,and Shinji Yonesaka
Abstract

With the declared purpose of “‘Connecting’ then ‘opening’ the door to the new world,” NTT WEST
seeks to contribute to the further development of communities and address a variety of challenges posedby changes in society by refining its technologies and wisdom and co-create new value. The entire NTT
Group has been working to actualize the Innovative Optical and Wireless Network (IOWN) concept. In
this article, we introduce NTT WEST’s efforts toward this end, especially related to the development of
the All-Photonics Network (APN) in creating use cases and providing the APN commercial service inthe form of IOWN1.0.
Keywords: optical transport network (OTN), real-time remote control, remote live

1. Introduction
As society changes drastically, NTT WEST aims tocontribute to the revitalization of communities andcreation of new value through co-creation with local
customers and partners. To address a variety of challenges affecting communities, NTT WEST is using
its networks, services, and solutions.
Challenges in a community are becoming more
complex. They include the lack of workers in local
industries due to declining birthrate and an aging
population and the need to maintain transportation
systems for the community. To achieve both economic development and solutions to social challenges, lifestyles will need to change drastically. Thesechanges will include the incorporation of informationand communication technology systems and otherdigital technologies that use data, artificial intelligence, and Internet of Things into many aspects ofdaily life.
The NTT Group has been studying the Innovative
Optical and Wireless Network (IOWN) as a technological platform that supports such social transformation and developing specific IOWN solutions and
NTT Technical Review

Vol. 21 No. 9 Sept. 2023

services. An example of such efforts is that NTT
WEST is engaged in conducting demonstrations ofuse cases to connect IOWN’s innovative technologies
to solutions for various social issues. We are also
developing commercial services using IOWN technologies. Some of these services are being rolled out
as the first applications of IOWN.
In the following sections, we introduce NTT
WEST’s co-creation efforts with a variety of partners
using the All-Photonics Network (APN) as examples
of applying the IOWN concept to solutions for communities. The APN is an element of IOWN andachieves low-power consumption and high-capacity
and low-latency communication. We also introduce
the features of the APN service in IOWN1.0,
launched in March 2023, as the first social implementation of the IOWN concept as well as examples ofcollaborative enterprises with partners using thisservice.
2. Remote live event using
APN-related technologies
The live-entertainment field is exploring new types
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Feature Articles

QUINTBRIDGE (Osaka)Musicians

Chorus(Main)

Chorus(Remote 1)

Chorus(Remote 2)

Conductor

Osaka-jo Hall (Osaka)

Transmission
equipment

Chorus(Remote 1)(Remote 2)

Cameras
Chorus(Remote 1)

Microphones

About 100
peopleVideoprocessing
equipment

Speakers

IOWN
APN

OPEN HUB Park (Tokyo)
Musicians

Chorus(Main)

Chorus(Remote 1)

Chorus(Remote 2)

Conductor

Conductor

CamerasTransmission
equipment
CamerasTransmission
equipment

Musicians

Microphones
Chorus(Main)

Speakers
Cameras

Chorus(Remote 2)

2000 people

Microphones

About 50
peopleMain venue

Speakers

Remote venues

Audio signal

Video signal

Fig. 1. Demonstration of real-time remote choral performance.

of events that integrate the real world and cyberworld, such as audience-less live shows and virtual
festivals. Through the development of IOWN APNrelated technologies for achieving high-capacity andlow-latency communication, the NTT Group is also
seeking to create such integration in a variety offields, including live entertainment. The NTT
Group’s technologies make it possible to connect
multiple locations and enable users to experience
them as one space.
With such background, NTT WEST conducted afield demonstration of a real-time remote choral performance connecting Tokyo and Osaka using technologies related to the APN (Fig. 1). For the 40th
anniversary of the choral concert “SUNTORY Presents Beethoven’s 9th with a Cast of 10,000,” held in
the Osaka-jo Hall and broadcast annually by Mainichi
Broadcasting System (MBS) since 1983, NTT WEST
connected three locations: Osaka-jo Hall, QUINTBRIDGE (Kyobashi district in Osaka), and OPEN
HUB Park (Tokyo), all separated by a total of 700 kmof optical fiber. APN-related technologies connected
the three different locations, each with a conductor,
orchestra musicians, and choral performers. Videolatency was kept to 15 ms one way (propagation timeof less than 1 video frame at 60 fps), resulting in an
NTT Technical Review

Vol. 21 No. 9 Sept. 2023

experience where video delay was not felt. Audiolatency was approximately 4 ms one way. This is thesame it takes for sound to travel 3 m in the same
space, meaning that this is the same latency musicians experience if they are 3 m apart on the samestage. Thus, with NTT’s APN technology, audio fromremote locations and audio from 3 m apart at thesame space could be received simultaneously, creating a new experience that transcends distance.
Latencies are not just due to data transmission but
also internal processing of data in equipment such as
cameras and displays. Because the latter has a major
impact on latencies, it is important to choose equipment with the shortest internal-processing time possible to achieve low latency. To share the excitement
and sensation of you-are-there realism, it is necessary
to enhance the experience in remote locations so theaudience there can have the same experience as theywould at the main venue. There is thus still muchresearch to be done in providing a richer experience.
The benefits of the APN are not just limited to thistype of field demonstration. Because there are manycases in which it can contribute to addressing social
challenges by bringing people together so they feelthey are side-by-side even when separated, we will
use the knowledge gained from remote live event to27

Feature Articles

Workplace
QUINTBRIDGE

Remote baseeSPARKLe KOBE

IOWN
(WiGig + APN)
Robot

Control

Field where different tasks are
performed by the robot

Remote control of service robot while
viewing remote videos via monitor

Fig. 2. Real-time remote robot control.

develop applications for the APN.
3. Remote robot control using the APN andhigh-frequency band radio
In regions with a growing aging population anddeclining birthrate, the decrease in the working population is a major issue to sustain the local economy.
The development of remotely operated robots thatcan perform necessary tasks anywhere without being
limited by physical location or physical characteristics of the operator can be effective for addressing
such an issue. However, such development faces thechallenge of ensuring sufficient communication
bandwidth and low-latency communication, which
are necessary for high-resolution video communication and real-time signal exchanges during remote
operation. With this background, NTT WEST collaborated with ADAWARP, which provides a platform for remote operation of robots, in a demonstration of real-time remote robot control (Fig. 2).
In the demonstration, a service robot in QUINTBRIDGE was controlled remotely from eSPARKLe
KOBE, a facility within the NTT WEST’s Hyogo
branch office, via an APN line. By viewing videofrom multiple cameras attached to the robot, therobot’s operator remotely performed tasks that
required detailed operations, such as pressing buttons
and opening and closing doors.
Because QUINTBRIDGE is where many workers
constantly carry out digital communication exchanges, using a 2.4- or 5-GHz wireless local area network
to connect to the robot may lead to operational issues
such as throughput degradation due to network-traffic congestion in the facility. Wireless Gigabit(WiGig), which uses the 60-GHz band was thus used
to avoid interference with the 2.4- and 5-GHz bands.
High-frequency radio bands, such as the 60-GHz
NTT Technical Review

Vol. 21 No. 9 Sept. 2023

band, cannot penetrate physical objects such as people, walls, and columns, so it is necessary to designbase stations that ensure line-of-sight propagation
within an area and develop technology to switch
between different base stations instantly when a robot
moves or rotates to maintain line-of-sight communication propagation with the robot. The first requirement was fulfilled using a direction-diversity scheme,
which places multiple base stations along the edgesof an area. The second requirement was achieved
using NTT Access Network Service Systems Laboratories’ site diversity control technology. Specifically,
the robot was equipped with two WiGig wirelessterminals, each connected to different base stations toensure communication on two different wirelesstransmission channels at all times.
By selecting the wireless terminal providing thebest wireless quality for each data packet for transmission, the robot could switch between communication channels on the basis of dynamic monitoring ofradio quality, resulting in lack of communicationinterruption even in an environment with obstructions. Therefore, the robot could transmit 4K-quality
video and control signals without interruption causedby radio interference or base-station switching, evenwhen moving within the facility. The robot’s operator
could thus successfully perform the demonstration’stasks. Even though the 4K video was compressedusing the AV1 codec, end-to-end transmission andreceiving took about 56 ms. This was less than 100
ms, which is considered the threshold above which
latency can be perceived [1]. The demonstration also
showed that an APN line can achieve sufficient communication capacity with a trivial amount of latency,
even in an environment in which multiple cameras
and robot sensors intermingle.

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Feature Articles

OTU4

ODU4 header is retained.

Latency-control information
is embedded.

OTU4

Terminal
equipment

Terminating
equipment

ODU4

OTU4

ODU4

Terminating
equipment

ODU4

Terminal
equipment

Latency-control information
is extracted.

Fig. 3. Optical network service.

4. Launch of APN IOWN1.0 service
NTT is providing the commercial APN IOWN1.0
service with a network service (high-speed broadband access service powered by IOWN) and terminal
equipment (“OTN Anywhere” powered by IOWN).
4.1 Network service
APN IOWN1.0’s network service achieves low
latency and zero signal fluctuations by eliminating
data queuing and signal conversion. By using theoptical transport unit 4 (OTU4) interface, a networkthat transparently transports Ethernet signals equivalent to 100 Gbit/s can be achieved (Fig. 3).
APN IOWN1.0’s network uses the optical transport
network (OTN) entirely for segments between user–
network interfaces. The OTN provides an encapsulated optical path and transmits and receives data inunits with maintenance overhead and error-correction
codes assigned for each client signal. By supporting
the OTN in all network-service segments, monitoring
and control signals for path monitoring and performance monitoring can be propagated end-to-end.
4.2 Terminal equipment
For APN IOWN1.0, OTN Anywhere [2] is used as
the terminal device equipped with latency visualization and adjustment functions. A distinctive functionof OTN Anywhere is its assignment of latencyadjustment-related control signals to the maintenance-overhead domain, thus achieving end-to-end
latency adjustment without network-communicationinterruption.
NTT Technical Review

Vol. 21 No. 9 Sept. 2023

5. Creating use cases with partners throughsocial implementation
As the first use case of NTT’s commercial APN
service (APN IOWN1.0) in western Japan, NTT
WEST and Yoshimoto Kogyo carried out a remoteentertainment event titled “Mirai no Owaraibu”(Future Comedy Live) on March 20, 2023 by connecting three locations in Osaka City—in Kyobashi(QUINTBRIDGE), Umeda (LINKSPARK), andNamba (Yoshimoto Manzai Theater) (Fig. 4).
By connecting the venues using APN IOWN1.0,
not only was low-latency video transmission
achieved, but the use of large, life-size video displays
at two locations, QUINTBRIDGE and the Yoshimoto
Manzai Theater, were made possible for this event.
Audiences at the two locations could watch real performers at each location and virtual performers fromthe remote locations via the low-latency life-size
video displays as if the performers were all in thesame space at the same time.
Thanks to the technological achievements of APN
IOWN1.0 in providing a realistic experience of
remote performances, 97.3% of the audience at
QUINTBRIDGE and the Yoshimoto Manzai Theatre
said they “did not feel any latency at all,” and 94.5%
said they were “satisfied with the event.” Throughthis effort, NTT WEST and Yoshimoto Kogyo succeeded in presenting a new form of entertainment.
6. Summary
We introduced NTT WEST’s efforts in carrying out
29

Feature Articles

LINKSPARK (Umeda)

QUINTBRIDGE (Kyobashi)
RemoteMicrophones

CamerasAudience

Wavelengths

APN
terminal
equipment

RemotePerformers

Uncompressedaudio

RemoteUncompressedUncompre
press
sse
ed
HDMII
HDM

Wavelengths

Uncompressedaudio

RemoteMicrophones

APN
terminal
equipment

APN
IOWN1.0

UncompressedUncompre
press
sse
ed
HDMI
HDMI

Low-latency transmission

Performers

CamerasMonitors

Monitors

RemoteAudience

RemoteUncompressed
HDMI

Uncompressed
HDMI

Yoshimoto Manzai Theater (Namba)
Wavelengths

Uncompressedaudio

RemoteAPNterminal equipment
Uncompressed
Uncompre
press
sse
ed
HDMI
HDMI

RemoteMicrophones

Performers
CamerasMonitors

Audience

RemoteUncompressed
HDMI

HDMI: high-definition multimedia interface

Fig. 4. First use case of commercial APN (APN IOWN1.0) in western Japan.

a remote live event and remote robot control as casesof using the APN to connect IOWN’s innovativetechnologies to solutions for various social challenges. We also presented a summary of the APN service
that NTT launched in March 2023 as the first offeringof IOWN services along with examples of co-creation with partners using the APN service.
Beginning with the launch of this commercial service, we are also seeking to stimulate the creation ofuse cases with a variety of partners and apply IOWN
to a variety of fields. For example, we expect the
APN service to be applied to mobile fronthaul, whichis planned as a social infrastructure in a wider rangeof fields, and to inter-datacenter connectivity. We areengaged in the development of services and technologies with the near-future goal of enabling visitors to

NTT Technical Review

Vol. 21 No. 9 Sept. 2023

the World Expo Osaka, Kansai, Japan to be held in
2025 to experience the value of IOWN through joint
ventures with more customers and partners.
References
[1]

[2]

K. Takeshita, K. Watanabe, K. Sato, K. Minamizawa, and S. Tachi,“Study on Telexistence LXIII –Study of Tolerance of Network Delay
for TELESAR3–,” The 15th Annual Conference of the Virtual Reality
Society of Japan, Sept. 2010 (in Japanese).
https://tachilab.org/content/files/publication/study_on_telexistence/
te063.pdf
T. Ohara, T. Oda, F. Inuzuka, K. Shintaku, H. Takechi, S. Usui, D.
Shimazaki, and H. Ohnishi, “Delay Managed Network for APN
IOWN1.0,” NTT Technical Review, Vol. 21, No. 9, pp. 32–36, Sept.
2023.
h ttp s ://n tt- r e v ie w. jp /a r c h iv e /n ttte c h n ic a l. p h p ? c ontents=
ntr202309fa4.html

30

Feature Articles

Atsushi Ota

Kenji Matsumoto

Engineer, IOWN Promotion Office, NTT
WEST Corporation.
He received a B.S. in industrial engineeringfrom Setsunan University, Osaka and joined
NTT WEST in 2009. He is engaged in researchand development of transmission systems andoptical communications.

Service Developer, Value Design Department,
NTT WEST Corporation.
He received an M.S. in informatics from
Kyushu Institute of Technology, Fukuoka, andjoined NTT in 2017. His is engaged in developing network services.

Masayuki Nishiki

Katsuhiro Tanabe

Senior Manager, IOWN Promotion Office,NTT WEST Corporation.
He received a B.E. in architectural engineeringin 1998 and M.E. in engineering from Osaka
University in 2000. He joined NTT WEST in
2000, where he is engaged in research and development of transmission systems and opticalcommunications.

Service Developer, Value Design Department,
NTT WEST Corporation.
He received a B.S. in engineering from Shimane University and joined NTT in 2010. His isengaged in developing network services.

Hideaki Kimura

Shinji Yonesaka

Senior Manager, R&D Center, NTT WEST
Corporation.
He received a B.E. in information engineeringand M.E. and Ph.D. in engineering from University of Tsukuba, Ibaraki, in 2006, 2008, and 2011.
He joined NTT Access Network Service Systems
Laboratories in 2011 then moved to NTT WEST
in 2020. He is engaged in research and development of transmission systems and optical communications. He is a member of the Institute ofElectronics, Information and Communication
Engineers (IEICE) and Information Processing
Society of Japan (IPSJ).

NTT Technical Review

Vol. 21 No. 9 Sept. 2023

Engineer, IOWN Promotion Office, NTT
WEST Corporation.
He received an M.E. in engineering from
Osaka University and joined NTT WEST in
2011. He is engaged in research and developmentof transmission systems and optical communications.

31

Feature Articles: Launch of APN IOWN1.0 Service

Delay Managed Network for
APN IOWN1.0
Takuya Ohara, Takuya Oda, Fumikazu Inuzuka,
Kengo Shintaku, Hiroto Takechi, Soichiroh Usui,
Daisaku Shimazaki, and Hiroyuki Ohnishi
Abstract

This article introduces the concept of the Delay Managed Network to control communication latency
and the optical transport network (OTN) equipment, called OTN Anywhere, which has delay-measurement and delay-adjustment functionalities. NTT operating companies, NTT EAST and NTT WEST,
released the first-version service of the All-Photonics Network (APN) of the Innovative Optical andWireless Network (IOWN), APN IOWN1.0, in March 2023 that is based on OTN Anywhere. In addition
to the benefit of low latency approaching the physical limit, this service provides end-to-end layer-1
paths without latency fluctuation and offers delay measurement and delay adjustment of each end-to-end
layer-1 path. The Delay Managed Network can enhance user experience of various remote activities.
Keywords: IOWN, All-Photonics Network (APN), Delay Managed Network

1. Importance of low-latency communication
With the rapid advances in communication technologies, the number of remote activities based on
sophisticated communication services is increasing.
This trend has been accelerated due to the drastic
lifestyle change caused by the COVID-19 pandemic.
Such remote activities include conventional video
streaming based on one-way communication as wellas interactive video and voice streaming based on bidirectional communication.
Figure 1 shows a nation-wide remote e-sports competition across multiple cities as an example of such
remote activities. Communication latency is extremely important because instantaneous response is a
critical component of players’ user experience (UX)
while playing games. Communication latency differs
depending on players’ location and can fluctuate due
to network congestion. This unfair communication
environment is a critical problem in supporting
remote e-sports competitions across multiple cities,
especially professional e-sports games. Therefore,
very low latency and fair communication environNTT Technical Review

Vol. 21 No. 9 Sept. 2023

ments are critical for use cases such as e-sports.
A next-generation communication service with low
latency and latency manageability will play a key rolein e-sports as well as live-entertainment, remote collaboration, and up-and-coming XR (cross reality) andthe metaverse. Given this situation, we have investigated networking technologies that can enable theflexible control of communication latency.
2. Concept of Delay Managed Network
We have created a new networking concept, theDelay Managed Network, to drive the UX revolution
on the basis of advanced layer-1 networking technologies. It has the following three major features(also illustrated in Fig. 2).
(1) Providing end-to-end layer-1 paths
The Internet is an indispensable part of daily life,
and its importance will continue to increase. However, its best-effort nature sometimes causes undesirable situations, for example, sudden increases incommunication latency, capacity loss, and possible
loss of packets due to network congestion. These32

Feature Articles

SapporoFukuoka

Tokyo
Osaka

Fig. 1. Nation-wide remote e-sports competition (example of a remote activity).

problems significantly degrade UX in many use
cases. Given these considerations, we want to makeit possible to provide communication services that
do not have such a limitation. In other words, wewant to offer end-to-end layer-1 paths, which feature low absolute latency, zero-latency fluctuation,and predetermined capacity, even in the face of
network congestion.
(2)	Measuring and adjusting communication latency
Given the increased importance of low-latency
communication, we want to create paths that offer
latency that is as low as possible as well as delaymeasurement and delay-adjustment functionalities
to provide unprecedented UX. From the viewpointof end users, delay measurements of only the links
the communication path uses might be meaningless, so we have to provide the means to measure
and adjust end-to-end latency along the path. If weuse a communication protocol that inherently haslatency fluctuation, delay measurements will beineffective because latency constantly changes.
Given this consideration, it is important to use acommunication protocol that has no latency fluctuation.
(3) Accommodating various client signals
The Delay Managed Network has to accommodate various client signals from end users to support
various use cases. In addition to Ethernet, which is
widely used, the Delay Managed Network should
support various client signals such as video andvoice.
3. Enabling technologies for IOWN1.0
We developed an optical transport network (OTN)
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Vol. 21 No. 9 Sept. 2023

End-to-end
layer-1 path

Delay
ManagedNetworkDelaymeasurement&
Delayadjustment

Accommodationof various
client signals

Fig. 2. Concept of Delay Managed Network.

equipment called OTN Anywhere to enable the features of the Delay Managed Network (Fig. 3).
OTN Anywhere is basically connected to the edgeof the All-Photonics Network (APN) and used in
combination with metro/long-haul transport equipment such as dense wavelength division multiplexing(DWDM) transmission systems. OTN Anywhere canbe connected to various transmission systems worldwide via the standard interface of the optical transport
unit 4 (OTU4), which is specified in the OTN (Optical Transport Network) standards of International
Telecommunication Union - Telecommunication
Standardization Sector (ITU-T). A layer-1 communication path, called the optical data unit (ODU) path,33

Feature Articles

What is OTN Anywhere?
1. Connected to the edge of APN
2. Installed at customer premises
3. Provide new functionality

client signal

OTN
Anywhere--- connected to various DWDM equipment--- accomodate client signals at customer premises--- provide delay measurement and delay adjustment

DWDM
transport system

DWDM
transport system

OTN
Anywhereclient signal

APN

layer-1 path for user ODUk
layer-1 path for multiplexing ODU4
short reach signal OTU4

metro/long haul OTU4 / OTUCn

short reach signal OTU4

Fig. 3. Features of OTN Anywhere and network configuration.

Table 1. Outline specifications of OTN Anywhere.
Specification
Network interface

OTU4

Client interface

10GbE
100GbEODU delay measurement
ODU delay adjustment

ODU

ODU4

Accuracy

1.2 µsODU

ODU4Maximum

20 ms

Fig. 4. Appearance of OTN Anywhere.

between OTN Anywhere is transparently transported
by DWDM transmission systems, so OTN Anywhere
can be implemented regardless of the type of DWDM
transmission system used. OTN Anywhere can beinstalled at customer premises and directly transfer
user signals into the OTN. OTN Anywhere also has
our newly developed delay-measurement and delayadjustment functionalities. Table 1 lists the specifications, and Figure 4 shows the appearance of OTN
Anywhere.
OTN Anywhere has the following technologies inregard to the three features described in Section 2.
(1) Providing end-to-end layer-1 paths
We use the OTN protocol for OTN Anywhere.
The OTN is widely used as a backbone infrastructure in metro/long-haul networks worldwide. The
OTN protocol offers 100% capacity guarantee, lowlatency approaching the physical limit, and no
NTT Technical Review

Vol. 21 No. 9 Sept. 2023

latency fluctuation. While end users merely see theprotocol, we have developed OTN Anywhere as a
one-rack-unit equipment, which can be installed atcustomer premises to provide genuine end-to-end
layer-1 communication paths. OTN Anywhere candedicate an end-to-end ODU path to the user, as
shown in Fig. 3. ODU paths can be multiplexed intohigher-rate ODUs without affecting other users’
traffic. This enables the efficient use of lambda
capacity when one user does not use the full capacity of a wavelength.
(2)	Measuring and adjusting communication
latencyOTN Anywhere provides delay-measurementand delay-adjustment functionalities for end-to-end
ODU paths.
34

Feature Articles

TX/RX
TX/RX

TX/RX

DM

MAP/DEMAP
MAP/DEMAP

DA

TX/RX

TX/RX

MUX/
DEMUX

DA

DM

2. Delay adjustment
intensional
adjustment

delay

MAP/DEMAP

MUX/
DEMUX

MAP/DEMAP

TX/RX

MAP/DEMAP

TX/RX

MAP/DEMAP

TX/RX

unavoidable
transmission delay

1. Delay measurement

beforeafter

non-intrusive round-trip delay measurement

DA: delay adjustment
DM: delay measurement
MUX/DEMUX: multiplexer/demultiplexer
Tx/Rx: transmitter/receiverFig. 5. Function block of OTN Anywhere with delay functionalities.

The delay-measurement function is for measuring round-trip delay in micro-second accuracy. At
one end of the ODU path, OTN Anywhere adds
delay-measurement bits, which then traverse theODU path, to be loop-backed at the other end of the
ODU path and reach the original end point (Fig. 5).
This function is compliant with the delay measurement specified in ITU-T Recommendation G.709.
It is still difficult to measure end-to-end round-trip
delay from the viewpoint of the end user because
the OTN protocol is used only in the backbone network, not end-to-end. As OTN Anywhere measures
the round-trip delay, it enables end-to-end measurement.
In addition to delay measurement, OTN Anywhere can offer delay adjustment if needed (Fig. 5).
The delay-adjustment function has two operation
modes: instantaneous delay adjustment and hitlessdelay adjustment. The instantaneous-delay-adjustment mode adjusts the delay of the ODU path via
short-hit, which means that bit errors are observed
during adjustment. This mode is useful, for example, for drastic delay adjustment before ODU-path
activation. The hitless-delay-adjustment mode
adjusts the delay of the ODU path without short-hit,
which means that no bit errors are observed during
adjustment. This function is useful for fine-tuning
delay under the in-service condition.
These two functionalities, delay measurementand delay adjustment, enable the flexible control ofcommunication latency. They are implemented inlayer 1 and independent from upper-layer protocols, so they support many use cases.

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(3) Accommodating various client signals
OTN Anywhere currently supports one of themost major client signals, Ethernet (10GbE/
100GbE). This means that it is possible to transport
Ethernet as well as various video and voice signals
by combining off-the-shelf products. These video
and voice signals are mapped into the OTN via
Ethernet, but as there is no Ethernet switch along
the ODU path, no significant latency increase or
fluctuation increase occurs.
OTN Anywhere can measure and adjust the latencyof the ODU path. Measured latency values can bepassed, for example, to other systems, servers, or
operators. These measured delay values support realtime processing, server processing, or latency-sensitive operation. In remote e-sports competition among
multiple cities, the communication latency of eachvenue is first measured, then the delay of each venue
is set to be the same to create fair competition.
4. Perspectives on OTN Anywhere evolution
We have just taken the first step of APN IOWN1.0
by developing OTN Anywhere. We plan to evolve the
APN by continuously creating new functionalities
and technical innovations. The direction of OTN
Anywhere evolution includes supporting various
consumer and legacy signals, adding new functionalities such as path protection, and providing economical connections to the APN. We are making efforts tocreate innovations on the basis of potential customer
needs and plan to offer unprecedented UX to eachcustomer in the near future.

35

Feature Articles

Takuya Ohara

Group Leader, Transport Innovation Laboratory, NTT Network Innovation Laboratories.
He received a B.E. and M.E. in electronicengineering from the University of Tokyo in
1998 and 2000. He joined NTT Network Innovation Laboratories in 2000. His research interests
include optical fiber communication, specifically, optical networking, OTN evolution, and highspeed and large-capacity optical transmission
systems. As a group leader, he leads the Transport Network Design Research Group targetingthe creation of new optical network concepts,
new functionalities, and network equipment
architectures. He has extensive experience withOTN standardization activities having engaged
in ITU-T Study Group 15 (SG15) for more than
10 years. He was a visiting researcher at AT&T
Labs Research, Middletown, New Jersey, from2007 to 2008, where he was involved in research
on an optical path tracing technique. He is amember of the Institute of Electronics, Information and Communication Engineers (IEICE) of
Japan and the Institute of Electrical and Electronics Engineers (IEEE).

Takuya Oda

Senior Research Engineer, Transport Innovation Laboratory, NTT Network Innovation Laboratories.
He received a B.E. in electrical engineeringand M.E. in informatics from Hokkaido University in 2010 and 2012. He joined NTT Network
Innovation Laboratories in 2012 and studied
maintenance and operation of optical network.
He is currently studying the Delay Managed
Network that improves the end-to-end user experience, especially in latency-sensitive services.
He is a member of IEICE.

Fumikazu Inuzuka

Senior Research Engineer, Supervisor, Transport Innovation Laboratory, NTT Network Innovation Laboratories
He received a B.E. and M.E. in applied physics
from the Tokyo University of Agriculture andTechnology in 2002 and 2004. He joined NTT
Network Innovation Laboratories in 2004, where
he is researching photonic transport and processing systems and photonic networking systems.
He is a member of IEICE.

Kengo Shintaku

Research Engineer, Transport Innovation Laboratory, NTT Network Innovation Laboratories.
Since joining NTT Network Innovation Laboratories in 2013, he has been researching OTNs.
He is currently engaged in ITU-T SG15 activities
addressing OTN technologies.

NTT Technical Review

Vol. 21 No. 9 Sept. 2023

Hiroto Takechi

Senior Research Engineer, Photonic Transport
Network Systems Project, NTT Network Innovation Center.
He received a B.E. and M.E. from Tokyo Institute of Technology in 2004 and 2006. He joined
NTT Network Service Systems Laboratories in2006, where he was involved in developing
Multi-Service Protocol Platform (MSPP) systems. He is currently engaged in the research anddevelopment (R&D) of a delay-adjustment transmission system that equalizes delay times
between multiple distributed locations to achieve
the Delay Managed Network that transforms theuser experience in delay-sensitive services.

Soichiroh Usui

Senior Research Engineer, Transport System
Project, NTT Network Innovation Center.
He received a B.S. and M.S. in fundamental
physics from Kyoto University in 2003 and2005. He joined NTT Network Service Systems
Laboratories in 2005, where he was engaged in
the R&D of optical transmission systems. From2013 to 2017, he was in charge of deploying new
optical transport network systems and developing a new optical line service at NTT EAST. He
has now back to researching and developing
optical transmission systems. He is a member ofIEEE Communications Society.

Daisaku ShimazakiGroup Leader, Transport System Project, NTT
Network Innovation Center.
He received a B.S. in applied chemistry and
M.S. in materials science from Keio University,
Kanagawa, in 1999 and 2001. He joined NTT
Network Service Systems Laboratories in 2001,
where he researched and developed multi-layer
network virtualization as a research engineer. He
has been in his current position since January
2014 and engaged in the development project for
Beyond 100G Optical Cross Connect Systems at
NTT Network Innovation Center. He is a member of IEICE. He was the recipient of the TELECOM System Technology Award from the Telecommunication Advancement Foundation in2016 and Maejima Hisoka Award from Tsushinbunka Association in 2022.

Hiroyuki Ohnishi

Director, Photonic Transport Network Systems
Project, NTT Network Innovation Center.
He received a B.E. and M.E. from Waseda
University, Tokyo, in 1996 and 1998. He joined
NTT Network Service Systems Laboratories in1998 and has been engaged in research on thenext-generation mobile IP network architecture.
He is currently engaged in the R&D of All-Photonic Network architecture and systems.

36

Feature Articles: Keynote Speeches and Workshop
Lectures at Tsukuba Forum 2023

NTT as a Creator of New Value andAccelerator of a Global Sustainable
Society
Katsuhiko Kawazoe
Abstract

The first commercial service of the Innovative Optical and Wireless Network (IOWN), IOWN1.0, waslaunched in March 2023. This article introduces its accomplishments as well as the future that will bepossible with its successors IOWN2.0, 3.0, and beyond. This article is based on the keynote speech given
by Katsuhiko Kawazoe, NTT senior executive vice president, at Tsukuba Forum 2023, held on May 17
and 18, 2023.
Keywords: IOWN, photonics-electronics convergence, APN

1. New medium-term management strategy:
IOWN-driven creation of new value(from concept to reality)
The Innovative Optical and Wireless Network(IOWN) * has gained recognition since it wasannounced four years ago in May 2019. It is now thecenterpiece of NTT’s new medium-term management strategy.
“Innovating a Sustainable Future for People andPlanet” is the fundamental principle of this strategy.
One of its key points is being conscious of our planet.
The NTT Group is not just concerned about itself; wemust develop sustainable business together witheveryone on Earth. When IOWN was announced, we
had planned to begin service in 2030. However, after
Osaka was chosen as the host city of Expo 2025, we
decided to move up the schedule by five years. Nevertheless, there were still some who considered thislaunch as being too late, so we decided to start the
IOWN commercial service this March.
2. Seeking to change the gameIn the past, Japan played a major role on the worldstage when the “logic of quality” was central to business success. Quality was a key factor in creating
NTT Technical Review

Vol. 21 No. 9 Sept. 2023

things that provided value in the real world.
The era of the “logic of numbers” then arose. This
paradigm is exemplified by the Internet. Voluminous
data are collected and converted to marketing data,
which leads to even larger markets and spurs morecollection of data. This is the world we live in, aworld in which the logic of numbers is dominant.
I believe what will follow next from the logic ofnumbers is the “logic of value.” I think it will be atime when we look back to how we as humans lived
happily by mutually recognizing our diverse values
and views of happiness around the world and truly
respecting them. We should make it an era that is notjust about numbers but our well-being. Whenever weconsider what is needed technologically to achievethis, we see that photonics is its technological foundation.
What we need to do is forget for the time being that
all approaches are created intentionally by us humans,such as the Internet, and return once again to thebasics. This is precisely the role of IOWN. We areusing IOWN to achieve the next generation of communications from the fifth generation (5G) to 6G*

IOWN: A new communication infrastructure that can provide
high-speed broadband communications and enormous computing
resources by using innovative technologies including opticaltechnologies.

37

Feature Articles

Fig. 1. Seeking a game-change.

(Fig. 1).
3. From digitization for efficiency to digitization
to create value
It is often said that digitization is important. However, there are two types of digitization, digitization
to improve efficiency and to create new value. Innovation that solves the problems we face and breaks
through limits is difficult to achieve with digitization
to improve efficiency alone. Therefore, we must also
aim to achieve digitization that creates new value.
The datacenter business is a critical area for the
NTT Group. Data volume and power consumption
are growing exponentially. The rise of general-purpose artificial intelligence (AI) and generative AI, as
exemplified by ChatGPT, will accelerate thesetrends. Generative AI technologies such as ChatGPT
have shown that they can deal with both general andspecialized queries with extremely high accuracy.
This is something we seriously need to be aware of
because data will increase explosively (Fig. 2).
NTT has been studying optical technology and thepotential of photonics for a long time. When comparing electricity and photonics, we see that they differ
in the energy it takes to transmit information. Whenthe distance from point A to point B increases, electricity naturally requires more energy than photonics
to transmit information. With electricity, more energy
is consumed as the operating frequency increases.
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However, with photonics devices there is almost no
increase in power consumption. We can save energy
by applying optical technology to information transmission. The Tsukuba R&D Center has become a hub
for the spread of this technology around the world,and Japan leads the world in the penetration of fiber
optics. NTT’s research labs have focused on the useof fiber optics in data transmission since the 1960s.
Another of our goals is to also use optical technology
in data processing. NTT was the first in the world tocreate optical transistors. The possibility of using
light in data processing led to the announcement of
the IOWN concept.
4. Benefits of IOWN
By reducing power consumption to 1/100 andincreasing transmission capacity 125-fold comparedwith conventional networks, IOWN promises tomake possibilities dreamt of a reality. We thuschanged our policy of offering a technology after its
development is complete to an approach of offering
iterations each time they mature. The All-Photonics
Network (APN) IOWN1.0 service was launched on
March 16 this year on the basis of this new paradigm(Fig. 3).
5. Start of APN IOWN1.0 service
The APN is a network connected end-to-end with38

Feature Articles

Fig. 2. Worldwide data volume and power consumption of datacenters.

Fig. 3. Advantages of IOWN.

fiber optics. Because the network is composed entirely of optical connections, not only is low latency
achieved but so is “OTN (optical transport network)
Anywhere” capability, which allows latency time tobe controlled by terminal equipment and the latency
level to be fixed (Fig. 4).
Ahead of providing this APN service, NTT conducted several field demonstrations. Events such as
NTT Technical Review

Vol. 21 No. 9 Sept. 2023

musical concerts, e-sports tournaments, and live
comedy shows were held to enable many users toexperience the benefits of IOWN in offering entertainment services in the future. Many use cases of
IOWN in the field of entertainment were introduced.
The “Mirai no Ongakukai” event (“Music Concert of
the Future”), held in February, demonstrated how theAPN could provide low-latency content. Musicians
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Feature Articles

Fig. 4. IOWN1.0 APN.

Fig. 5. Co-creation with partners in diverse fields.

in Tokyo and Osaka, separated by a physical distanceof 700 km but connected by fiber optics, performed alive classical concert together. The latency experienced by the musicians was the same they would
experience if their instruments were 3 m apart on thesame stage. This experiment demonstrated that latency could be controlled using the IOWN APN, as
explained above. Users of an IOWN concert applicaNTT Technical Review

Vol. 21 No. 9 Sept. 2023

tion could receive the performance almost instantaneously as there is no need to buffer the content.
Figure 5 illustrates the companies and organizations that are using the APN IOWN1.0 service topioneer new businesses with NTT.
In the datacenter sector, the NTT Group currently
holds the third largest market share globally. To further develop this business, we will continue our
40Feature Articles

Fig. 6. Expansion of APN with services.

efforts to achieve carbon neutrality by 2030 using the
IOWN technology. At the same time, we will continue with our efforts to reduce the energy consumed
by datacenters.
6. Towards IOWN2.0 and beyond
IOWN2.0 involves two areas: networks and computers.
6.1 Networks
Step 2 after the launch of the APN IOWN1.0 service is to improve power efficiency 13-fold, including for inter-prefecture communications. In Step 3,
we will increase power efficiency 100-fold (Fig. 6).
From 2024, we plan to connect major cities, andfrom 2026, we plan to provide this connectivity as abusiness service to customers who need it anywherein Japan. In combination with this service, we seek toimplement “optical access network design based onconcatenated loop topology” currently being developed by the Tsukuba R&D Center in the expansion of
the APN.
6.2 Computers
In June 2023, NTT will launch [launched] NTT
Innovative Devices Corporation, responsible for thedevelopment, manufacture, and distribution of photonics-electronics convergence devices. This company will provide the following photonics-electronics
NTT Technical Review

Vol. 21 No. 9 Sept. 2023

convergence technologies that can be used not only inNTT’s own networks but also in general computers.
•	(IOWN2.0) Photonics-electronics convergencedevices for board-to-board connections:
IOWN2.0 will reduce equipment’s power consumption and improve its performance throughoptical board-to-board connections.
•	(IOWN3.0) Photonics-electronics convergencedevices for chip-to-chip connections: In
IOWN3.0, further reduction in power consumption will be possible with the introduction ofphotonics-electronics convergence devices forchip-to-chip connections.
•	(IOWN4.0) Photonics-electronics convergencedevices for intra-chip (die-to-die) connections:
IOWN4.0 is expected to reduce power consumption to 1/100 that of current consumption by connecting waveguides in a chip optically.
IOWN photonics-electronics convergence technology will change computing architecture. Computing
architecture will first experience a major shift to disaggregated computing then to a memory-centricarchitecture. Such an architecture will become thecritical foundation on which AI and robots operate.
NTT plans to invest 3 trillion yen annually over the
next five years to develop not only technologies thatserve as the foundation of IOWN but also services,
applications, and platforms that leverage IOWN
(Fig. 7).

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Feature Articles

Fig. 7. New value creation with data-driven applications (Smart World).

7. IOWN Global ForumThe IOWN Global Form was launched in January
2020. It currently has 120 member companies andorganizations. We aim to make IOWN not just a go-to
solution for datacenters but also a household namethat customers can trust. We hope that IOWN willlead to a new form of economic security where Japan

will once again become a major contributor on theworld stage. We wish to share a grand vision inwhich, instead of relying on the technology of a specific country, companies around the world cooperate
without the need for competition or disputes and playnecessary mutual roles to establish an ecosystem
together.

Katsuhiko Kawazoe

Senior Executive Vice President, NTT Corporation.
He joined NTT in 1987 and served as seniorresearch engineer of the Cyberspace Laboratories and the Cyber Solutions Laboratories of the
Cyber Communications Laboratory Group from2003 to 2007. He became vice president of the
Research and Development Planning in 2008,
head of the Service Innovation Laboratory
Group, Service Evolution Research Laboratory
in 2014, head of the Service Innovation Laboratory Group in 2016, senior vice president, headof Research and Development Planning, memberof the Board in 2018, and executive vice president, head of Research and Development Planning in 2020. He has served as senior executive
vice president, representative member of theBoard since 2022.

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42

Feature Articles: Keynote Speeches and Workshop
Lectures at Tsukuba Forum 2023

Past and Future Prospects for
Advanced Operation of AccessNetwork Facilities
Takashi Ebine
Abstract

NTT is responsible for building and maintaining access network facilities, providing a variety of services ranging from fixed-line telephones using metal cables to data communications using optical fibers.
In this context, we at NTT Access Network Service Systems Laboratories are researching and developing smart-engineering (design and construction) and smart-maintenance (maintenance and operation)technologies with the aim of operational innovation through digital transformation of such access network services. We are also taking on the challenge of creating new value in areas other than telecommunications by using assets at our communication facilities.
Keywords: operational innovation, advanced operation, access network facilities

1. Operational innovation in accessnetwork services
NTT is responsible for building and maintaining
access network facilities and providing a variety ofservices ranging from fixed-line telephones using
metal cables to data communications using opticalfibers. Against this backdrop, especially in the fiberto-the-home (FTTH) sector, which underwent a
major transformation from metal to light, operationalinnovation has advanced significantly. As we movetoward the coming Innovative Optical and Wireless
Network (IOWN) era, we expect to see a significant
transformation in services, along with a transformation in operational innovation.
In the early days of FTTH, Nippon Telegraph andTelephone Public Corporation was privatized against
the backdrop of the deregulation of telecommunications in 1985, and in the 1990s, the construction ofaccess network facilities underwent a major transformation due to the increase in the number of new
telecommunications carriers and discussion on opening up NTT’s optical-fiber network facilities to othertelecommunications service providers. With theadvent of competing services, such as asymmetric
NTT Technical Review

Vol. 21 No. 9 Sept. 2023

digital subscriber line, it was difficult to predict optical demand, and additional construction could occur,
so it was a time when trial and error was repeated in
the construction and maintenance of access network
facilities. In such an era, the study of aerial-opticaldrop fiber-cable-bundling technology, which started
mainly from external factors, is an example of how
operational sophistication could be achieved throughthe thorough use of existing facilities and space.
Although there were various challenges in the
beginning toward implementing this technology, we
verified and evaluated the reliability of the installation equipment and communications in response tolong-term environmental changes. It is now the basic
construction method for laying optical cables
throughout Japan.
As we approach the IOWN era, NTT is preparing
for technology accumulation and field deployment
through research and development to address publicdemand for telecommunications infrastructure. We at
NTT Access Network Service Systems Laboratories
are advancing the operational sophistication of accessnetwork facilities from the perspective of operationalinnovation. This article presents two initiatives thathave been or will be deployed in the field.
43

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2. Upgrading facilities by digitizing thereal world
One of the operational innovation initiatives that isbeing rolled out is the “Upgrading facilities by digitizing the real world” by using vehicles called mobile
mapping systems (MMSs).
Digital Twin Computing, which digitizes and simulates the real world, is one of the components of
IOWN. Outside facilities, such as utility poles, that
support communication services will continue torequire constant maintenance and operation. The
inspection of outside facilities is carried out visually
and with human experience and expertise, but further
efficiency is required due to the shrinking workforce.
We have been engaged in research and developmentof technology to automatically extract information oncommunication facilities from point-cloud dataacquired from an MMS and quantify facility conditions such as deflection and thereby developed astructural-deterioration determination system that
contributes to increasing the efficiency of inspection
work.
The more flexible the pole, the more likely it is tohave lateral cracks and be unsafe. By running an
MMS to automatically extract utility poles with large
deflections and visually inspect only those poles, it ispossible to greatly reduce inspection work. Deflection can be calculated automatically by simply inputting point-cloud data into the system, which can also
contribute to skill-lessness. To achieve remote andautomated construction work, such as construction ofcolumns, we are currently advancing technology for
automatically recognizing facilities, heavy machinery, and the surrounding environment in real timefrom point-cloud data and pursuing the ultimate inaccuracy to quantify the structural conditions ofultrathin objects such as cables (Fig. 1).
Point-cloud data has been used in various industries
such as automated driving and surveying, and theaccuracy of measurement equipment has been
improved and their cost has decreased. However, the
MMS used by each NTT Group company has different specifications, so processing and analysis software must be changed in accordance with the dataacquired, which makes aggregation and deployment
inefficient. In addition to automatic-recognition technology and facility-condition-quantification technology, facility requirements for acquiring point-clouddata inexpensively and with high precision from allcommunication facilities and the unification of MMS
specifications of the NTT Group will be studied.
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Other

Heavy machinery(Arm part)Wall
Utility pole
Locationsin close proximity

Other

Fig. 1. Example results of real-time automatic recognition.

3. Research and development of concatenatedloop topology for IOWN optical access networks
This section introduces two major activities for
operational innovation. The first is the activity related
to concatenated loop topology for optical access networks.
The star-type topology for the optical access network supporting FTTH services, which was designed
to be economical, has been used. However, businessdemand from various service operators is expected toincrease, including mobile-carrier demand such as
Beyond fifth-generation mobile communications
system (5G)/6G. Unlike FTTH, which has been used
to address certain consumer demand by replacing
metal cables with optical fiber cables, such businessdemand is uncertain in terms of the quantity and location, so problems such as inefficiency and inability torespond to highly reliable and flexible services are
expected.
On the basis of this background, we established aconcatenated loop topology for optical access networks that combines multiple cable loops in multiple
stages and proposed a wiring method that optimizes
higher reliability and high capability to accommodate
optical demand with uncertainties for locations andquantity (Fig. 2). Loop topology has been considereda reliable and flexible wiring topology since the earlydays of FTTH, but this concatenated loop topology
can improve reliability and flexibility not only near
central offices but also in areas far from the central
offices by using this multi-stage configuration. It canalso select optical paths with a high degree of freedom. For optical access networks in the IOWN era,
we are considering overlaying the current FTTH
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Optical-access-network
design based onconcatenated loop topology
Optical cross-connection
Routeredundancy
Path selectivity

Fiber availability

Fig. 2. Optical-access-network design based on concatenated loop topology.

OutputInput• City-planning information
Design-assist
technology• Map information

Input
×

• Facility information(Pipeline, maintenancehole, utility pole)

Suggestion of cable route

Installation scenario
Overlay, partial installation,etc.

Evaluation of design results
Cost simulation

Fig. 3. Overview of design-assist technology.

network with a new layer of this concatenated loop
topology.
However, to introduce new wiring methods, it isessential to estimate future demand and conductsimulations of capital investment and construction
volume. This should enable the design of an opticalaccess network on the basis of current equipment(i.e., availability of pipelines, utility poles, pull-up
points, and optical cables). Manually carrying out
such design requires an enormous amount of work,and the design quality varies depending on thedesigners’ skills. Therefore, we are advancing
research and development on design-assist technology for automatically generating appropriate cableNTT Technical Review

Vol. 21 No. 9 Sept. 2023

route proposals and assisting designers by inputting
necessary information (Fig. 3). This technology is
expected to make it easier to verify various deployment patterns in accordance with demand forecasts
and area characteristics because it can significantly
reduce the time for designing (about one to two days),which normally takes two weeks to one month byhand per area in a central office.
We will investigate the introduction of concatenated loop topology to green fields, such as smart cities,
while aiming to deploy it in actual optical accessnetworks. Operations and other aspects of this wiring
method will be developed in parallel, and researchand development will be promoted to implement
45Feature Articles

Measuringequipment

Obtain vibration data of optical fibers using
high-precision optical-measurement technology

Fiber selection
by switch

APN
High-speedtransfer
Convert to environmental
information

DCI
Public data
Other sensing data

Advanced processing
and interpretation

Use in several typesof industries: solvingsocial issues

Fig. 4. Optical-fiber environmental monitoring.

IOWN along with related technology development.
4. Optical-fiber environmental monitoring using
current communication cables and advanced
optical-fiber sensing technology
The other operational innovation initiative that is
expected to be developed is optical-fiber environmental monitoring.
By using current optical fiber cables for communications, which are the largest assets owned by the
NTT Group, as sensors, we are advancing researchand development on optical-fiber environmental
monitoring with which vibrations generated by various events occurring around optical fiber cables areobserved with our proprietary high-precision distributed acoustic sensing (DAS), and the resulting vibration data are analyzed and interpreted to identify
events occurring around the cables (Fig. 4).
The technological requirements to achieve thisinclude the ability to measure the distribution ofvibration applied to an optical fiber with high precision, ability to process a large amount of measured
data in real time to visualize the state of vibration, andability to analyze and interpret the data to identify
events. To improve the accuracy of vibration measurement, NTT’s DAS is based on phase optical timedomain reflectometry (phase-OTDR) with frequency-division multiplexing (FDM) pulses. FDM phaseOTDR is used to observe more accurate phases of
NTT Technical Review

Vol. 21 No. 9 Sept. 2023

backscattered light and generate vibration waveforms
with less noise than before by using FDM pulses andour unique noise-reduction algorithm. Although theprocessing of a large amount of data is a major issue,
real-time data processing is possible due to the development of calculation algorithms and the use of fieldprogrammable gate arrays. Figure 5 shows example
measurement results of vehicle traffic by FDM
phase-OTDR using a communication optical fiber
cable laid in an underground pipeline installed alongan actual roadway. The horizontal axis shows the
distance from the measuring device, and the verticalaxis shows the elapsed time. The red and blue bars
represent the measured amount of phase rotation of
the optical signal and correspond to the amplitude of
the vibration applied to the optical fiber. Therefore, apair of red and blue lines indicates how one vehicle istraveling on the road. The number of pairs represents
the number of vehicles. The slope of the line means
the speed of the vehicle. This measurement can also
be conducted in real time. The area around A in the
figure, where the slope of the line increases, indicatesthat the traffic signal has turned red and vehicles haveslowed down and stopped. This is expected to be
applied to traffic-flow monitoring in smart cities andother areas. Vibration information obtained with suchhigh precision is expected to be used to understandthe surrounding conditions of optical fiber cables,
and its use is progressing.
Optical-fiber environmental monitoring is also46

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Elapsed time (s)

0

A

10

20

800

1000

1200

1400
Distance (m)

1600

1800

Fig. 5. Vehicle-traffic-measurement results with optical fiber cables laid in field.

aimed at achieving more advanced sensing by combining it with IOWN. We are considering the use of
the fiber-path switching function of the All-Photonics
Network (APN) to enable planar measurements byfreely selecting the optical fibers to be sensed and thetransfer of large amounts of measurement data by thehigh-speed transmission function of the APN. By
using the abundant computing resources of the datacentric infrastructure (DCI) to analyze and interpretmeasurement data at high speeds, we expect to immediately generate environmental information. Discussions are currently focused on the configuration of
the connection between the sensing device andswitching function of the APN.
Optical-fiber environmental monitoring can provide new value to optical-fiber-cable networks as asensing infrastructure. With the aim of expanding theapplication area, we will work on developing a method for measuring vibration with higher precision andover a wide area, accumulate knowledge and experi-

ences to implement the method as a device, anddevelop systematization and use cases.
5. Direction of future initiatives
In the United States, companies, including Google,
are focused on the road shoulder as a business opportunity and are competing for the rights to smart cities
and autonomous driving. Innovation using current
assets and technologies is occurring at the same time,and NTT believes that it is important to use spacesuch as using the aerial-optical-drop fiber-cablebundling technology, and effectively use current
assets such as in optical-fiber environmental monitoring for innovation. With regard to the vast amount ofassets held by NTT, such as utility poles and cables,
we will continue to take on the challenge of creating
new value, not only through the effective use of such
assets but also in areas other than telecommunications, drawing on past good practices.

Takashi Ebine

Executive Research Engineer, Project Manager, Access Network Management Project, NTT
Access Network Service Systems Laboratories.
He joined NTT in 1997 and has been engaged
in the developmental research of access network
facilities. He served in this position from July
2020 to June 2023 and is currently vice president,
head of NTT Access Network Service Systems
Laboratories.

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47

Feature Articles: Keynote Speeches and Workshop
Lectures at Tsukuba Forum 2023

Low-latency and Energy EfficientTechnologies for New Optical AccessNetworks
Tomoaki Yoshida
Abstract

NTT laboratories are engaged in the research and development of technologies to overcome increasingdata volume, power consumption, and network delay. This article introduces the technologies that contribute to low latency and power saving of optical access networks being researched and developed by
the Optical Access System Project at NTT Access Network Service Systems Laboratories.
Keywords: optical access systems, low-latency FDN, APN

1. High expectations for low-latency opticalaccess networks
The concept of the Innovative Optical and Wireless
Network (IOWN) envisions a network and information processing infrastructure to provide high-speed,
high-capacity communications and enormous computational resources using innovative technologies
that are based on photonics and optics, and the IOWN
Global Forum (IOWN GF), which brings together
various companies for discussions, is taking the leadin implementing IOWN. IOWN GF aims to naturally
provide capabilities beyond human cognition thatenable extremely high-definition video, perceptual
displays, and large-volume transmission. It also discusses use cases and technologies for computing
resources and devices. IOWN GF exemplifies use
cases that enhance immersion and extend human cognition, such as cyber-physical systems that collectdata from a large number of cameras and sensors inreal time to predict the future and perform autonomous control as well as remote-control and extendedreality navigation.
Low-latency and robust networks are key for theseuse cases. For example, low latency and stability of
the communication environment are required in theguidelines for remote surgery formulated by the Japanese Surgical Society [1]. To cope with the decrease
NTT Technical Review

Vol. 21 No. 9 Sept. 2023

in the working-age population, improving productivity and reducing dangerous work are urgent issues, so
a low-latency and stable network to enable precise
remote control is necessary.
2. Network technology for low latency
The All-Photonics Network (APN), which is acomponent of IOWN, is expected to provide stablelow-latency communication that takes advantage ofthe characteristics of optical fiber. However, toachieve precise remote operation, it is necessary not
only to control the delay in transmission but also
reduce the time required for the input, processing,and output of information, which is part of the delayof the entire communication, and to have a mechanism that enables smooth remote operation to continue even if a failure occurs at various points.
We at the Optical Access System Project in NTT
Access Network Service Systems Laboratories aredeveloping a network technology called low-latency
functional dedicated network (FDN) to enable quick
response to changes in network and services and rapidly allocate and swap computing resources for edge
processing (Fig. 1). This makes it possible to provide
a stable low-latency and low-jitter network for theentire remote-control system, including optical andedge processing sections. For the practical and48

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High-speed closed-loop control technology
for network & computing resources
Collection

Control
Co-analysis
Control

Collection

Network
qualityServerstatusServercontrol

Apps

Network
control

Edge server

APN

Mobileinformation

Opticalnetwork
control

Apps
Edge server

Collect mobile
information

Analysis

Control
optical network

Optical-wireless cooperative control

Fig. 1. Low-latency FDN.

widespread use of remote-control services, we areadvancing “high-speed closed-loop control technology for network & computing resources,” whichtakes advantage of cloud technology, especially edge
computing, to enhance the reliability of image processing and artificial-intelligence processing (Fig. 2).
This technology monitors connection quality by collecting information on the status of both the networkand edge server, ensuring stability by switching theroute and server simultaneously when quality
becomes degraded. At the Tsukuba Forum 2023, wedemonstrated an application that uses this high-speed
closed-loop control technology for network & computing resources to operate a remote robot-arm
through a screen and maintain high stability to continue operations even if remote-control delay iscaused by the increasing background traffic on theedge server.
We are also researching and developing anotherlow-latency technology that can be used to stably
control multiple robots in a factory. It leverages timeaware shaper (TAS) technology [2] for mission-critical data transfer between multi-access edge computing (MEC) and a large number of terminals locatedNTT Technical Review

Vol. 21 No. 9 Sept. 2023

near the user. TAS technology was originally developed as a traffic-control technology for mediating
and multiplexing communications with very strict
delay requirements, but it is applicable to a mechanism that executes cooperative control among multiple switches, i.e., the entire network. We demonstrated how this technology can ensure low latency
for each control message between any terminal in afactory and MEC, enabling the simultaneous control
of multiple delicate robotic arms.
3. Optical-power-supplied optical network unit
A promising use case for Internet of Things (IoT) is
data collection in rural areas and unmanned environments, such as for observations in mountainous areas
and the sea, and for monitoring facilities such as
dams. In such areas, however, it is sometimes difficult to supply power through power lines. IoT devices
using solar cells, energy-harvesting technology, andlow power wide areas (LPWAs) have been proposed,
but there are still many issues with stable power supply and the limitation of radio propagation distance.
For example, in these severe climate environments,
49

Feature Articles

High-speed closed-loop control
technology for network &computing resources
ServerstatusNetwork
qualityServercontrol

Apps

Assist function (ex.)
Focuses on what is happening
Overlays operating procedure on video
Displays the amount of force used to grip
the object being operated

Network
control

Edge server
APN

Fast switching of edge servers and network
simultaneously during quality degradation

Edge server

End-to-end
delay

Apps

Servicerequirements

Real-time management
by responding rapidly

Conventional
This technology
TimeFig. 2. High-speed closed-loop control technology for network & computing resources.

solar cells and energy-harvesting technologies are notstable power sources due to topography, weather,
vegetation, and other conditions, and LPWAs are also
limited in their propagation distance. Therefore, NTT
Access Network Service Systems Laboratories is
researching and developing an optical-power-supplied optical network unit (ONU) that enables IoT
communication by using optical energy supplied
through optical fibers [3].
We developed a prototype optical transceiver that
operates with low power consumption and demonstrated it by installing a mechanism in which the
ONU is put to sleep when communication is notneeded to thoroughly suppress average power consumption while being charged by optical powerreceived by the photoelectric conversion unit (Fig. 3).
We demonstrated this optical-power-supplied ONU
at the Tsukuba Forum 2023.
4. Research and development trends of
Photonic Gateway
NTT Access Network Service Systems Laboratories conducted research and development on the Photonic Gateway (Ph-GW), which provides the functions required for user accommodation in the APN

NTT Technical Review

Vol. 21 No. 9 Sept. 2023

through full-mesh optical paths by end-to-end connecting terminals and using as little electrical processing as possible. The Ph-GW consists of (1)remote wavelength control, (2) multiplexing/demultiplexing, (3) pass/block, (4) turn back, and (5) add/
drop using optical technology and provides end-toend main signal opening and stopping without theuser being aware of the communication protocol.
NTT Access Network Service Systems Laboratories
has demonstrated that these five functions are feasible [4, 5]. These functional block groups constituting
the Ph-GW were proposed in IOWN GF and consented to be described as APN-G [6]. Functions (2),(3), and (5) are possible by extending the functions ofa reconfigurable optical add/drop multiplexer(ROADM), which is an optical transmission device,and the Open ROADM Multi-Source Agreement has
started to discuss them. Other goals, such as remotemonitoring control, miniaturization of APN terminals, and cost reduction, are being investigated; thus,
we will continue researching and developing the
Ph-GW. We believe that users should experience the
APN with available technology so that they will
become aware of its advantages. Therefore, we would
like to expand functions through continued researchand development.

50

Feature Articles

Optical-power-supplied ONU
IoT devices
Photoelectric-conversion unit

Optical powersourceHeat-wave camera

Optical power
supplyAcceleration
sensorPower supply
Opticalcommunication
Opticalline
terminal

O/E
conv.

Low-powerconsumption
optical TRx

Transmission equipmentwith sleep control

Temperature
sensorWirelessconnection(BLE)

Illuminancesensor

BLE: Bluetooth Low Energy
O/E: optical to electrical
TRx: transceiverFig. 3. Optical-power-supplied ONU demonstration.

References
[1]
[2]
[3]

Japanese Surgical Society, “Guidelines for Telesurgery,” June 2022
(in Japanese), https://jp.jssoc.or.jp/uploads/files/info/info20220622.
pdf
IEEE Std 802.1Qbv-2015: “IEEE Standard for Local and metropolitan area networks -- Bridges and Bridged Networks - Amendment 25:
Enhancements for Scheduled Traffic,” Mar. 2016.
H. Katsurai, Y. Fukada, R. Miyatake, H. Nagoshi, M. Sekiguchi, andT. Yoshida, “Sleep/Active Operation of Optical-power-supplied ONU
without Electricity for Rural IoT,” Proc. of the 2022 International
Conference on Emerging Technologies for Communications (ICETC2022), O2-2, Tokyo, Japan, Nov./Dec. 2022. https://doi.org/10.34385/
proc.72.O2-2

[4]

[5]

[6]

Y. Senoo, S. Kaneko, T. Kanai, N. Shibata, J. Kani, and T. Yoshida,“Demonstration of In-service Protocol-independent End-to-end Optical Path Control and Restoration in All-Photonics Network,” Proc. of
Optical Fiber Communication Conference (OFC) 2022, W3G.4, San
Diego, CA, USA, Mar. 2022. https://doi.org/10.1364/OFC.2022.
W3G.4
M. Yoshino, S. Kaneko, N. Shibata, R. Igarashi, J. Kani, and T.
Yoshida, “New Photonic Gateway to Handle Digital-coherent and
IM-DD User Terminals and Enable Turn-back Connections in Metro/
Access-integrated All-Photonics Network,” Proc. of OFC 2023,
W3F.5, San Diego, CA, USA, Mar. 2023. https://doi.org/10.1364/
OFC.2023.W3F.5
IOWN GF, “Open All-Photonic Network Functional Architecture,”
Jan. 2022. https://iowngf.org/wp-content/uploads/formidable/21/
IOWN-GF-RD-Open-APN-Functional-Architecture-1.0-1.pdf.

Tomoaki Yoshida

Executive Research Engineer, Project Manager, Optical Access Systems Project, NTT AccessNetwork Service Systems Laboratories.
He received a B.E., M.E., and Ph.D. in communication engineering from Osaka University
in 1996, 1998, and 2007. In 1998, he joined NTT
Multimedia Systems Development Center. In
1999, he moved to NTT Access Network Service
Systems Laboratories, and has been engaged inresearch on next-generation optical access networks and systems. From 2013 to 2015, he wasinvolved in the research on a wavelength divisionmultiplexing/time division multiplexing-passive
optical network (PON) and worked on the standardization of optical access systems such as
NG-PON2. He is a member of the Institute ofElectrical and Electronics Engineers (IEEE) andInstitute of Electronics, Information and Communication Engineers (IEICE).

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51

Feature Articles: Keynote Speeches and Workshop
Lectures at Tsukuba Forum 2023

Wireless Technologies for
Accelerating High-capacity
Transmission, Low Energy, andApplication-area Expansion
Takeshi Onizawa
Abstract

This article describes recent research and development of wireless technologies for the sixth-generation mobile communications system (6G) and the Innovative Optical and Wireless Network (IOWN) at
NTT Access Network Service Systems Laboratories. We at NTT Access Network Service Systems
Laboratories believe that IOWN and 6G have the same targets for future networks. Therefore, to actualize 6G/IOWN, we are investigating wireless technologies focusing on high-capacity transmission by
combining them with optical technologies, coverage extension for the sky including satellite-communication systems, application-area expansion, and low energy as the common wireless technologicalissues. This article introduces these wireless technologies and their future prospects.
Keywords: 6G, IOWN, high capacity

1. Introduction
NTT proposed the Innovative Optical and Wireless
Network (IOWN) [1] in May 2019 to construct future
optical and wireless networks for the 2030s. IOWN
will provide innovative optical technologies, hightransmission capacity, and huge computer resources
compared with conventional networks. However, thesixth-generation mobile communications system(6G) has been announced worldwide and focuses on
extreme high data rate/capacity, coverage extension,and low energy [2], which have been published inwhite papers of many research institutes [3]. In Japan,
NTT DOCOMO first published a white paper related
to 6G wireless technologies in January 2020 and has
updated its content for the 5th edition in Nov. 2022
[2].
We at NTT Access Network Service Systems Laboratories believe that IOWN and 6G have the sametargets for future networks. Therefore, we are investigating wireless technologies combined with optical
NTT Technical Review

Vol. 21 No. 9 Sept. 2023

technologies for actualizing 6G/IOWN. However, weneed to obtain worldwide agreement for the future of
6G. Therefore, NTT and NTT DOCOMO are expanding 6G collaboration with world-leading vendors [4]in Japan and overseas.
Regarding the wireless technologies for 6G, it iseffective to use the millimeter-wave and sub-terahertz bands to increase transmission capacity. However, we need to use a large amount of wireless equipment to transmit wireless signals. This is becauseradio-propagation loss increases in higher frequency
bands such as millimeter-wave and sub-terahertz
bands. Therefore, we also need a more flexible wireless-area design compared with conventional cellular
network design. We have been investigating a new
radio (NR) network topology in the space domain, as
shown in Fig. 1. To achieve this topology, we use
many remote radio units (RRUs), which consist of
wireless equipment and antennas, to transmit wireless signals. Therefore, distributed multiple-input
multiple-output (MIMO) is effective in transmitting
52

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IAB or repeater with
on-glass antenna

Small node mounted
on signboard orvending machine

Small node on traffic
lights or street lights

A-RoF

RIS

Legacy deployment

Mobile IAB
A-RoF

New-type deployment

Source: NTT DOCOMO, “White Paper 5G Evolution and 6G (Version 5),” Jan. 2023.
IAB: integrated access and backhaul
RIS: reconfigurable intelligent surface

Fig. 1. Example solution of NR network topology [2].

wireless signals from different RRUs. We connect acentral station (CS) to RRUs by using optical fiber
because of low optical transmission loss. To use theadvantages described above, we proposed a distributed MIMO system connected by analog radio overfiber (A-RoF) in higher frequency bands.
Because we construct a flexible network topology
by using this NR network topology, this topology isalso suitable for coverage extension involving satellites and high altitude platform stations (HAPSs) andapplication-area expansion.
This article introduces wireless technologies focusing on high-capacity transmission, coverage extension, application-area expansion, and low energy,
which are common issues with 6G/IOWN and their
future prospects [5].
2. High-capacity transmission
We now describe the distributed MIMO systems inhigher frequency bands, as shown in Fig. 2. We use
A-RoF, which connects a CS to RRUs.
2.1 A-RoF
As shown in Fig. 2, a star topology is the basic
topology for A-RoF transmission. However, a cascade topology is considered from the viewpoint of
NTT Technical Review

Vol. 21 No. 9 Sept. 2023

network flexibility. A cascade topology uses opticalpower splitters and an optical multiplexer/demultiplexer. Therefore, optical transmission loss passing
through these optical devices increases. Consequently, there is the problem of a limited number of connecting RRUs using a conventional cascade topology.
To solve this problem, we proposed a cascadetopology approach that involves using an opticalthin-film filter. This filter enables the selected wavelength with low optical transmission loss to passthrough and reflect other wavelengths, which makes
it possible to increase the number of connected
RRUs.
By aggregating RRUs’ signal processing, which
requires high energy, at a CS, A-RoF enables simple
and low-power-consumption RRUs. We also investigated a remote beamforming scheme [6] and conducted an experiment of 5G-NR signal transmission,
which is based on the physical specification of 5G
NR developed by the 3rd Generation Partnership
Project (3GPP), using the remote beamforming
scheme with beam table. This experiment successfully demonstrated simultaneous 4K-video transmission in both uplink and downlink directions.
We also measured the error vector magnitude(EVM) of 5G-NR signals by using 20-km single
mode fiber from a CS to RRUs. The measured EVM
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RRU

Economical and flexible area
deployment with A-RoF

CS
Simultaneous-beam-searchmethod with multiple
distributed antennas

Shielding prediction and MIMO
stream control using received
signal level variation

Fig. 2. Distributed MIMO systems in higher frequency bands.

0.47%

1.03%

2.29%

3.36%

(1) SG direct-connected(2) After RoF transmission(3) Antenna input port

(4) 5.0 m over the air

SG: signal generator

Fig. 3. Measured EVM and signal constellation.

and signal constellation on each measured point of
the experimental system are shown in Fig. 3. On thebasis of the measured EVM of 5 m over the air, we
confirmed about 3.36% EVM performance, which
satisfies the 3.5% requirement by the 3GPP physicallayer specification for 256 quadrature amplitude
modulation [5].
2.2 Distributed MIMO technology
There are several issues, described in a previous
study [2], that need to be addressed for developing a
distributed MIMO system in higher frequency bands.
To construct MIMO propagation paths, we use multiple distributed antennas as the transmitting points.
This subsection introduces technologies for controlling distributed propagation paths.
To operate many RRUs effectively, high-density
deployment of RRUs is required. Therefore, we alsoneed to carry out a large amount of beam-search processing. To solve this problem, we proposed a simulNTT Technical Review

Vol. 21 No. 9 Sept. 2023

taneous-beam-search method with multiple distributed antennas in RRUs that use the same frequency
bands and search timing. We found that this method
experimentally achieves better performance compared with the conventional method. The search timewith our method is not proportional to the number of
RRUs and terminals [5]. It should be noted that thismethod does not increase beam-search overhead
resources in the time domain.
NTT, NTT DOCOMO, and NEC demonstrated a
distributed MIMO system, which enables continuous
wireless connections in the 28-GHz band by eliminating shielding issues [7]. This system adaptively
selects connected RRUs’ antennas on the basis of theenvironmental information of radio propagation andterminal location with the distributed-control
approach. An overview of the experimental area andsystem is shown in Fig. 4. We compared A-RoF
transmission with coaxial cable transmissions interms of throughput performance. This system
54

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25 m

Distributed antenna

Mobile terminal antennax2

Distributed antennas
2
1
0
4m
5m

Coaxial
cable

14 m

Distributed antenna

Basestationequipment

Mobile terminal
Route of mobile terminal “Y”
85 cm
70 cm
3

5m

Pillars
4

Mobile terminal cart

4m 5Distributed antennas
Base-stationequipment

Fig. 4. Overview of the experimental area and system.

consists of distributed MIMO with A-RoF transmission, which connects a CS to two RRUs. We experimentally confirmed wireless transmission with bidirectionally time-division duplex operation in distributed MIMO using A-RoF transmission for the
28-GHz band. A-RoF transmission achieved almost
the same throughput performance as coaxial cabletransmissions.
3. Coverage extension
NTT is pursuing the Space Integrated Computing
Network, which achieves 100% coverage area
including terrestrial and non-terrestrial, by using themulti-layered non-terrestrial network (NTN) system[8]. As shown in Fig. 5, the multi-layered NTN system consists of geostationary orbit (GEO) satellites,
low-Earth orbit (LEO) satellites, and HAPSs. Therefore, we can select the optimum wireless transmission route by taking into account the effect of radio
propagation loss and channel capacity. For example,
because the wireless-transmission route has increased
path loss due to rain attenuation, we can control thewireless-transmission route by selecting the clearweather route without rain attenuation. Therefore, we
proposed a route-control technique to increase thechannel capacity of the multi-layered NTN system [5,8].
Satellite communication requires a high-capacity
feeder-link from the satellite to earth station. This isbecause the satellite must transmit a huge amount of
NTT Technical Review

Vol. 21 No. 9 Sept. 2023

data from many terminals on Earth through the service-link. From this point of view, we studied satellite
MIMO transmission of the feeder-link and developed
prototype satellite MIMO equipment, which will be
used in the experimental evaluation in LEO [8]. NTT
has been cooperating with the Japan Aerospace
Exploration Agency (JAXA) to demonstrate the practicality of satellite MIMO technology in LEO. NTT
and JAXA will continue the experimental evaluationof this technology with the Innovative Satellite Technology Demonstration-4*, followed by an experimental evaluation with the Innovative Satellite Technology Demonstration-3 [5].
4. Application-area expansion
To increase the potential advantages of high-capacity transmission and coverage extension, we investigated the following two wireless technologies byfocusing on application-area expansion.
The first is the base-station-selection-control technology that is based on localization information using
wireless communication radio. A localization technology has attracted attention for 6G. The conventional base-station-selection technology uses the*Innovative Satellite Technology Demonstration-4 and Innovative
Satellite Technology Demonstration-3: Projects in JAXA’s Innovative Satellite Technology Demonstration Program to provide
opportunities for on-orbit testing of equipment and parts developed by private companies, universities, and research institutions
by installing them on satellites.

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Multi-layered NTN
GEO layer
network

Route candidate

LEO layer
network

Route candidate

Latency and capacity conditions
are based on each layer network.

NTN intelligent
controller

HAPS layer
network
RainfallNTN routecontrol

Route candidate
No communication

Terminal

Earth station
Industry Earth station

Disaster area

Internet

Core network

Fig. 5. Route-control technologies in the multi-layered NTN, which includes satellite and HAPS networks.

ReceiverTransmitter: Fresnel zone;
prolate ellipsoidal regions of space between
and around a transmitter and receiver.

Fig. 6. Practical image of non-contact damage-inspection technology.

received-signal-power-based approach without sleep
control in the base station. Our technology uses theterminal-localization information using wirelesscommunication radio to recognize the communication area. Therefore, it enables the terminal to precisely select the base station without use of localization systems, such as the Global Positioning System.
We evaluated the performance of our base-stationselection-control technology using the license-free
60-GHz band. This evaluation experiment involved
using a wireless local area network system, called
WiGig, located on a formula car traveling over 300
km/h as a terminal. We also conducted an experimentfrom the view point of low energy in base stations [9].
When the formula car approached two base stations,
one base station was powered on and the otherremained off. The other base station is then poweredwith the formula car approaching by using our localization technology. It should be noted that the forNTT Technical Review

Vol. 21 No. 9 Sept. 2023

mula car traveled over 260 km/h. We found that our
technology decreased the active time of base stations
by 60% compared with the conventional technology.
The second technology is for non-contact damage
inspection of large structures [10]. We began a practical experiment on applying this technology to inspecta wind power windmill to contribute to a future carbon-neutral society. We expect good results by applying this technology to the inspection of ocean-based
wind-power equipment. This technology can also be
combined with the coverage-extension technologies
described above.
As shown in Fig. 6, our non-contact inspection
technology transmits a weak radio signal between
two drones sandwiching the target structure (weakradio equipment can be operated without a license).
Our technology detects and analyzes the variation in
the received signal level at the receiver drone. Therefore, we can detect the damage on a large structure in56

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a non-contact manner. The conventional technology
requires a non-operation period because it requires
on-site visual structural inspection as well as inspection from images. We plan to use our non-contact
damage-inspection technology in combination withthe conventional technology to shorten the nonoperation period.
5. Conclusion
This article described our research and development of wireless technologies for actualizing 6G/
IOWN and their future prospects. We expect toincrease the performance of wireless technologies byfocusing on high-capacity transmission, coverage
extension, and low energy. We also expect to expand
the application area of wireless technologies byachieving these targets.
References[1][2]

NTT, “NTT Technology Report for Smart World 2022,” July 22,2022.
https://www.rd.ntt/e/download/NTT_TRFSW_2022_E.pdf
NTT DOCOMO, “White Paper 5G Evolution and 6G (Version 5),”Jan. 2023.
https://www.docomo.ne.jp/english/binary/pdf/corporate/technology/
whitepaper_6g/DOCOMO_6G_White_PaperEN_v5.0.pdf[3] M. Latva-aho and K. Leppänen (Eds.), “Key Drivers and Research
Challenges for 6G Ubiquitous Wireless Intelligence,” 6G Research
Visions, No. 1, University of Oulu, Sept. 2019.
[4] NTT press release, “DOCOMO and NTT Expand 6G Collaborations
with World-leading Vendors Including Ericsson and Keysight Technologies,” Feb. 27, 2023.
https://group.ntt/en/newsrelease/2023/02/27/230227a.html[5] T. Onizawa, N. Kita, T. Miyagi, and F. Yamashita, “Recent Researchand Development of Wireless Techniques for Realizing 6G/IOWN
Concept,” IEICE Tech. Rep., CS2023-14, pp. 34–40, May 2023 (inJapanese).
[6] Y. Shirato, K. Ito, M. Suga, T. Arai, Y. Takahashi, Y. Yamamoto, andN. Kita, “R&D for Higher Frequency Bands Radio-over-Fiber Systems,” IEICE Tech. Rep., MWP2021-31, pp. 6–11, 2021 (in Japanese).
[7] NTT press release, “World’s First Successful Demonstration of Distributed MIMO That Continues Wireless Connections in the 28 GHz
Band by Eliminating Shielding Issues,” Oct. 31, 2022.
https://group.ntt/en/newsrelease/2022/10/31/221031a.html[8] F. Yamashita, J. Abe, and K. Itokawa, “R&D on Wireless Technologies in NTT Lab. for Space Integrated Computing Network,” IEICE
Tech. Rep., Vol. 122, No. 199, SAT2022-44, pp. 1–5, Oct. 2022.
[9] NTT press release, “The world’s first realization of wireless base stations with lower power consumption based on positioning information by using communication radio waves,” Mar. 31, 2023.
https://group.ntt/en/newsrelease/2023/03/31/230331a.html[10] NTT press release, “World’s first demonstration test of technology toenable non-stop inspection of windmills,” May 15, 2023.
https://group.ntt/en/newsrelease/2023/05/15/230515a.html

Takeshi Onizawa

Executive Research Engineer, Executive Manager, Wireless Entrance Systems Project, NTT
Access Network Service Systems Laboratories.
He received a B.E., M.E., and Ph.D. from
Saitama University in 1993, 1995, and 2003.
Since joining NTT in 1995, he has been engaged
in the R&D of personal communication systems,
high-data-rate wireless LAN systems, future
wireless access systems, and radio propagation.
He is in charge of management strategies of wireless communication systems. He received theBest Paper Award, Young Investigators Award,
and Achievement Award from the Institute ofElectronics, Information and Communication
Engineers (IEICE) in 2000, 2002 and 2006,
respectively. He received the Maejima Hisoka
Award in 2008 and the Best Paper Award at theInternational Symposium on Antennas andPropagation (ISAP) in 2016. He is a senior member of IEICE and a member of the Institute ofElectrical and Electronics Engineers (IEEE).

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Global Standardization Activities

A Report on ASTAP and WTSA-24
Regional Preparatory Meeting
Hiroshi Yamamoto and Jiro Nagao
Abstract

The 35th ASTAP (Asia-Pacific Telecommunity (APT) Standardization Program) Forum was held at
the Royal Orchid Sheraton Hotel and Towers in Bangkok, Thailand from April 17 to 20, 2023, and on
the following day, the 1st meeting of the APT Preparatory Group for WTSA-24 (World Telecommunication Standardization Assembly 2024) was held. We report on the status of each conference and the main
results of each.
Keywords: APT, ASTAP, WTSA-24

1. ASTAP overview
The Asia-Pacific Telecommunity (APT), an international organization promoting the development of
information and communication technology (ICT) in
the Asia-Pacific region, was established in 1979 andhas 38 member countries [1].
The APT Standardization Program (ASTAP),
which promotes standardization activities in the APT,
was established in 1998 [2]. The main objectives are(1) to contribute to international standardization bybuilding a cooperative and collaborative system forstandardization within the APT region, (2) nurture
standardization activists within the APT region andsupport the development of ICT skills among members within the region, especially those from developing countries, and (3) co-propose as a regional standardization organization to international standardization organizations such as the International Telecommunication Union (ITU). It is important to use
ASTAP as a platform to build camaraderie in the APT
region and contribute to developing countries, and as
a strategic platform for Japan for international collaboration in standardization activities.
The 35th ASTAP Forum (ASTAP-35) was held at
the Royal Orchid Sheraton Hotel and Towers in
Bangkok, Thailand from April 17 to 20, 2023, with a
total of 179 participants, which includes 123 on-site
participants, 27 sponsoring members, and 7 particiNTT Technical Review

Vol. 21 No. 9 Sept. 2023

pants from other international organizations in 24
APT member countries.
1.1 ASTAP’s new management teamAt the ASTAP-35, Dr. Hyoung Jun Kim (Electronic& Telecommunications Research Institute (ETRI)) of
the Republic of Korea was appointed as the ASTAP
chair, and Mr. Xiaoyu You (China Academy of Information and Communications Technology (CAICT))of China and Dr. Hideyuki Iwata (Telecommunication Technology Committee (TTC)) of Japan wereappointed as vice chairs for the second term. Amongthe executives of the Working Groups (WGs) andExpert Groups (EGs) under the WGs, the replacement regarding Japan of Mr. Noriyuki Araki (NTT)with Dr. Hideo Imanaka (National Institute of Information and Communications Technology (NICT)) as
the chair of EG DRMRS (Disaster Risk Management
and Relief System) and the replacement of Ms. Miho
Naganuma (NEC) with Mr. Hiroshi Takechi (NEC)as the chair of EG IS (Security) were approved.
Table 1 shows the new management team.
1.2 Industry Workshop
On the first day of the ASTAP-35, an Industry
Workshop was held under the theme “AI (artificial
intelligence), Metaverse, Open Source.” From Japan,
Mr. Leon Wong from Rakuten Mobile, Dr. Hideo
Imanaka from NICT, and Dr. Masahisa Kawashima
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Global Standardization Activities

Table 1. ASTAP management team. (the chairs/vice chairs elected from Japan are indicated in bold)
Group

ChairsVice Chairs

Dr. Hyoung Jun Kim (Korea)

Dr. Hideyuki Iwata (TTC, Japan)
Mr. Xiaoyu You (China)

WG Policy and Strategic Co-ordination (WG PSC)

Mr. Dao Ngoc Tuyen (Viet Nam)

Mr. Kaoru Kenyoshi (NICT, Japan)
Mr. Tong Wu (China)

Expert Group Bridging the Standardization Gap (EG BSG)

Mr. Dao Ngoc Tuyen (Viet Nam)

Mr. Ki-Hun Kim (Korea)
Mr. Masatoshi Mano (TTC, Japan)

Expert Group Green ICT and EMF Exposure(EG GICT&EMF)

Dr. Sam Young Chung (Korea)

Mr. Min Prasad Aryal (Nepal)
Mr. Nur Akbar Said (Indonesia)
Mr. Uttachai Mannontri (Thailand)

Mr. Kaoru Kenyoshi (NICT, Japan)

Mr. Quoc Binh Tran (Viet Nam)

Plenary

Expert Group ITU-T Issues (EG ITU-T)
Expert Group Policies, Regulatory and Strategies(EG PRS)No candidate

WG Network and System (WG NS)

Dr. Joon-Won Lee (Korea)

Dr. Hiroyo Ogawa (NICT, Japan)

Expert Group Future Network and Next Generation
Networks (EG FN&NGN)

Dr. Joon-Won Lee (Korea)

Mr. Kazunori Tanikawa (NICT, Japan)

Expert Group Seamless Access Communication Systems(EG SACS)

Dr. Hiroyo Ogawa (NICT, Japan)

Expert Group Disaster Risk Management and Relief
System (EG DRMRS)

Dr. Hideo Imanaka (NICT, Japan)

WG Service and Application (WG SA)

Ms. Miho Naganuma (NEC, Japan)

Dr. Jee-In Kim (Korea)

Dr. Toru Yamada (NEC, Japan)

Dr. Seung-yun Lee (Korea)
Ms. Li Haihua (China)
Dr. Heuisu Ryu (Korea)

Expert Group Internet of Things Application/Services(EG IOT)
Expert Group Security (EG IS)

Mr. Hiroshi Takechi (NEC, Japan)

Expert Group Multimedia Application (EG MA)

Dr. Hideki Yamamoto (OKI, Japan)

Dr. Dong il Seo (Korea)

Expert Group Accessibility and Usability (EG AU)

Dr. Jee-In Kim (Korea)

Ms. Wantanee Phantachat (Thailand)

from NTT spoke at the AI session, Metaverse session,and Open Source session, respectively. Table 2 lists
the workshop topics.
1.3 Outcome document
At the plenary meeting, final approval was given to
17 deliverables that had been discussed by the EGs
and subsequently agreed by the WGs.
2. APT WTSA-24 Preparatory Group
Following the ASTAP-35, the 1st meeting of the
APT Preparatory Group for World Telecommunication Standardization Assembly 2024 (WTSA-24) was
held on April 21, 2023, with a total of 127 participants, including 86 from 19 national administrations,
12 supporting members, and 18 from 3 internationalorganizations.
The APT WTSA-24 Preparatory Group is positioned as the preparatory meeting for WTSA-24 (toNTT Technical Review

Vol. 21 No. 9 Sept. 2023

be held in New Delhi, India, in October 2024) among
the APT member states (38 countries), and the 1st
meeting discussed management systems. FromJapan, Dr. Hideyuki Iwata of the TTC was appointed
as vice chair, Mr. Hiroshi Yamamoto of NTT (one ofauthors) as the chair of WG1 (ITU-T Working Methods), Ms. Miho Naganuma of NEC as vice chair of
WG2 (ITU-T Work Organization), and Ms. Eriko
Hondo of KDDI as vice chair of WG3 (Regulatory/
Policy and Standardization Related Issues). Table 3
shows the management team of the APT WTSA-24
Preparatory Group.
3. Future plans
In preparation for WTSA-24, the APT is planning a
total of 5 regional preparatory meetings, with thesecond preparatory meeting scheduled to be held
online in late January 2024.

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Global Standardization Activities

Table 2. Industry Workshop topics. (the speakers from Japan are underlined)
Program of ASTAP Industry Workshop
Introductory Remarks by Mr. Xiaoyu You
ASTAP Vice Chair/Industry Workshop Committee Member
Session 1: AI technology and standardization
Chair: Ms. Miho Naganuma, NEC Corporation, Japan• AI Standard Development and Potential Collaboration by Dr. Kangchan Lee, Director, ETRI, Rep. of Korea• Ethically Aligned Design of AI for Human Well-being by Dr. Kishik Park, President, Policy Research Institute for Human Dignity, Rep. of
Korea• ITU AI/ML 5G Challenge: Open platform for Datasets, Problem Statements and Pre-standards research by Mr. Vishnu Ram Ov, Vice
Chair of ITU-T FG AN, ITU• Chat GPT: Pinnacle of Conversational AI and its Impact on Modern Industries by Ms. Zhang Weimin, Senior Engineer, CAICT, PR China• ITU-T Focus Group on Autonomous Network by Mr. Leon Wong, Research Engineering Lead, Rakuten Mobile, Inc., Japan• Development of AI Technology and Market in China by Dr. Yuntao Wang, Deputy Chief Engineer, CAICT, PR China
Session 2: Metaverse
Chair: Dr. Toru Yamada, NEC Corporation, Japan• Standardization of Metaverse (ITU-T FG-MV) by Dr. Hideo Imanaka, Managing Expert, NICT, Japan• Embracing the Metaverse – What challenges to cope with and how? by Ms. Yuan Zhang, Director of AI Research Center, China Telecom,
PR China• Metaverse Trends and Standard Requirements by Dr. Younghwan Choi, Senior Research Staff, ETRI, Rep. of Korea
Session 3: Open-Source
Chair: Dr. Seungyun Lee, ETRI, Rep. of Korea• New kind of License issue with Open-Source Software by Mr. Yong Joon Joe*, Director, LSware Inc., Rep. of Korea• Open Infrastructure Consortia and Open-Source Software by Dr. Masahisa Kawashima, IOWN Technology Director, NTT, Japan• Driving AI Innovation via Open-Source Practices by Ms. Liya Yuan, Senior Engineer, ZTE, PR China
Conclusion of Industry Workshop by Mr. Xiaoyu You, ASTAP Vice Chair/Industry Workshop Committee Member

Table 3. A
 PT WTSA-24 Preparatory Group management team. (the chairs/vice chairs elected from Japan are indicated inbold)
APT WTSA-24

ChairsVice Chairs

Plenary

Dr. Hyoung Jun Kim(Korea)Dr. Hideyuki Iwata (TTC, Japan)
Mr. Sushil Kumar (India)
Mr. Xu Heyuan (China)
Mr. Behzad Ahmadi (Iran)Working GroupWG Chairs

WG Vice Chairs

WG1:
ITU-T Working
Methods

Mr. Hiroshi Yamamoto (NTT, Japan)

Ms. Minah Lee (Korea)
Mr. Wu Tong (China)
Mr. Abhay Shanker Verma (India)
Ts. Norzailah Mohd Yusoff (Malaysia)

WG2:
ITU-T Work
Organization

Dr. Kangchan Lee (Korea)

Ms. Miho Naganuma (NEC, Japan)
Mr. Arun Agarwal (India)
Mr. Qu Zhicheng (China)
Mr. Do Xuan Binh (Viet Nam)

WG3:
Regulatory/Policy andStandardization
Related Issues

Mr. Li Cheng(China)Ms. Eriko Hondo (KDDI, Japan)
Mr. Kihun Kim (Korea)
Mr. Avinash Agarwal (India)
Mr. Dao Ngoc Tuyen (Viet Nam)

References[1][2]

APT, https://www.apt.int/
ASTAP, https://www.apt.int/APTASTAPNTT Technical Review

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Global Standardization Activities

Hiroshi Yamamoto

Director, Standardization Office, Research andDevelopment Planning Department, NTT Corporation.
He received a B.S. and M.S. in information andcomputer science from Waseda University,
Tokyo, in 1999 and 2001. In 2001, he joined NTT
Service Integration Laboratories, where he wasengaged in the performance evaluation of Internet protocol (IP) networks, web applications, andvideo delivery. In 2006, he joined NTT Communications, where he engaged in the development of voice-over-IP systems. In 2010, hejoined NTT Network Technology Laboratories,
where he engaged in research and developmentof a quality-of-experience control video-delivery
mechanism. In 2015, he was assigned as the primary USA liaison based in Washington, D.C. andwas engaged in enhancing collaborations with
US academia and industry. In 2020, he was
assigned as a senior research engineer, supervisor at NTT Network Technology Labs andengaged in the research and development of
future network architecture. He is currently thehead of standardization office and oversees NTT
Group’s standardization activities.

NTT Technical Review

Vol. 21 No. 9 Sept. 2023

Jiro Nagao

Senior Manager, Standardization Office,Research and Development Planning Department, NTT Corporation.
He received a Ph.D. in information sciencefrom Nagoya University, Aichi, in 2007 andjoined NTT the same year. From 2007 to 2011, he
was engaged in research and development ofimage processing and content distribution technology. From 2012 to 2017, he worked for NTT
Communications, serving as the technical leaderof commercial video streaming services. From2017 to 2021, he was engaged in research anddevelopment of immersive media and presentation technology at NTT Service Evolution Laboratories. Since 2019, he has contributed to theinternational standardization efforts on immersive live experience (ILE) of ITU-T Study Group
16. He served as an editor of ITU-T H.430.4 (exH.ILE-MMT) and H.430.5 (ex H.ILE-PE) from2019 to 2020. He received the ITU Associationof Japan Encouragement Award in 2021. He iscurrently an associate rapporteur of ITU-T Study
Group 16 Question 8 (Immersive Live Experience, since 2022) and the leader of ILE Sub
Working Group of the Telecommunication Technology Committee (since 2020). He is a memberof the Institute of Electrical and Electronics
Engineers (IEEE), Institute of Electronics, Information and Communication Engineers (IEICE),
and the Japanese Society of Medical Imaging
Technology (JAMIT).

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External Awards
IEEE SLT 2022 Best Reviewer Award
Winner: Naohiro Tawara, NTT Communication Science Laboratories
Date: January 12, 2023
Organization: 2022 IEEE Spoken Language Technology Workshop(SLT 2022)
Distinguished Paper Award
Winners: Ayaka Sano, Motohiro Makiguchi, Takahiro Matsumoto,Hisashi Matsukawa, Ryuji Yamamoto, NTT Human Informatics
Laboratories
Date: May 23, 2023
Organization: Society for Information Display
For “Mirror-Transcending Aerial-imaging (MiTAi): An Optical
System that Freely Crosses the Boundary between Mirrored and RealSpaces.”Published as: A. Sano, M. Makiguchi, T. Matsumoto, H. Matsukawa, and R. Yamamoto, “Mirror-Transcending Aerial-imaging(MiTAi): An Optical System that Freely Crosses the Boundary
between Mirrored and Real Spaces,” Journal of the Society for Information Display, Vol. 31, No. 5, pp. 220–229, 2023.
Top 3% Paper Recognition
Winners: Taishi Nakashima, Tokyo Metropolitan University; Rintaro Ikeshita, NTT Communication Science Laboratories; Nobutaka
Ono, Tokyo Metropolitan University; Shoko Araki, NTT Communication Science Laboratories; Tomohiro Nakatani, NTT Communication Science Laboratories;
Date: June 4, 2023
Organization: The 2023 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP 2023)
For “Fast Online Source Steering Algorithm for Tracking Single
Moving Source Using Online Independent Vector Analysis.”
Published as: T. Nakashima, R. Ikeshita, N. Ono, S. Araki, and T.
Nakatani, “Fast Online Source Steering Algorithm for Tracking Single Moving Source Using Online Independent Vector Analysis,”
Proc. of ICASSP 2023, Rhodes, Greece, June 2023.
Top 3% Paper Recognition
Winners: Takatomo Kano, NTT Communication Science Laboratories; Atsunori Ogawa, NTT Communication Science Laboratories;
Marc Delcroix, NTT Communication Science Laboratories; Roshan
Sharma, Carnegie Mellon University; Kohei Matsuura, NTT Human
Informatics Laboratories; Shinji Watanabe, Carnegie Mellon University
Date: June 4, 2023
Organization: ICASSP 2023
For “Speech Summarization of Long Spoken Document: Improv-

NTT Technical Review

Vol. 21 No. 9 Sept. 2023

ing Memory Efficiency of Speech/Text Encoders.”
Published as: T. Kano, A. Ogawa, M. Delcroix, R. Sharma, K. Matsuura, and S. Watanabe, “Speech Summarization of Long Spoken
Document: Improving Memory Efficiency of Speech/Text Encoders,” Proc. of ICASSP 2023, Rhodes, Greece, June 2023.
Best Paper Award
Winners: Kenichi Fujita, NTT Human Informatics Laboratories;
Takanori Ashihara, NTT Human Informatics Laboratories; Hiroki
Kanagawa, NTT Human Informatics Laboratories; Takafumi Moriya, NTT Human Informatics Laboratories; Yusuke Ijima, NTT
Human Informatics Laboratories
Date: June 10, 2023
Organization: ICASSP 2023 Workshop on Self-supervision in
Audio, Speech and Beyond (SASB 2023)
For “Zero-shot Text-to-speech Synthesis Conditioned Using Selfsupervised Speech Representation Model.”Published as: K. Fujita, T. Ashihara, H. Kanagawa, T. Moriya, andY. Ijima, “Zero-shot Text-to-speech Synthesis Conditioned Using
Self-supervised Speech Representation Model,” Proc. of SASB
2023, Rhodes, Greece, June 2023.
IEEE Photonics Society 2023 William Streifer ScientificAchievement Award
Winner: Shinji Matsuo, NTT Device Technology Laboratories
Date: June 20, 2023
Organization: IEEE Photonics Society
For contributions to ultra-high speed, low power consumption
membrane lasers and their heterogeneous integration.
Outstanding Reviewer Recognition
Winner: Atsushi Ando, NTT Human Informatics Laboratories
Date: June 21, 2023
Organization: ICASSP 2023
Best Paper Award in Industry Innovation
Winner: Jin Uchiyama, NTT Access Network Service Systems
Laboratories
Date: July 4, 2023
Organization: The 28th Optoelectronics and Communications Conference (OECC 2023)
For “An Evaluation of Cost-efficiency by Extending ROADMbased Metro-access Converged Optical Networks to Cover Point-tomultipoint Connections.”
Published as: J. Uchiyama, R. Koma, K. Hara, J. Kani, and T.
Yoshida, “An Evaluation of Cost-efficiency by Extending ROADMbased Metro-access Converged Optical Networks to Cover Point-tomultipoint Connections,” OECC 2023, Shanghai, China, July 2023.

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