NTT Technical Review

April 2017 Vol. 15 No. 4
Feature Articles: Keynote Speeches at NTT R&D Forum 2017
Hiroo Unoura, President and Chief Executive Officer, NTT

Hiromichi Shinohara, Senior Executive Vice President and Head of Research and Development
Strategy Department, NTT

Feature Articles: NTT Tsukuba Forum 2016 Workshop Lectures
Research and Development Activities toward Smart and Flexible Future Network: NetroSphere
ConceptFlexible Access System Architecture: FASA



Research and Development of Innovative Operation Technology for Access Network
InfrastructureWireless Access Technologies to Enable a Variety of Services

Regular Articles


Low Latency Dynamic Bandwidth Allocation Method with High Bandwidth Efficiency for
TDM-PON

Global Standardization Activities


Report on ITU Telecom World 2016 and ITU Kaleidoscope 2016

Practical Field Information about Telecommunication Technologies
Case Study of Bolt Corrosion in Remote Subscriber Module-Feeder Point

Information

Event Report: Tsukuba Forum 2016

Short Reports
NTT, Ruhr-Universität Bochum, and Kobe University Develop a New Cryptanalytic Techniqueto Improve the Design of Lightweight Ciphers for Internet of Things

External Awards/Papers Published in Technical Journals and Conference ProceedingsExternal Awards/Papers Published in Technical Journals and Conference Proceedings

Feature Articles: Keynote Speeches at NTT R&D
Forum 2017

Generating New Value with xICT
—Advancing B2B2X Business—
Hiroo Unoura
President and Chief Executive Officer,
NTT
Overview

This article introduces NTT Group initiatives to promote the B2B2X(business-to-business-to-X) business model. The content of this article isbased on a lecture presented by Hiroo Unoura, NTT President and Chief
Executive Officer, at NTT R&D Forum 2017 held in February 2017.
Keywords: ICT, B2B2X, big data

Information and communication technology (ICT)
has evolved considerably over time as reflected by the
adoption of Internet protocol, expansion of broadband and mobile networks, development of compact
terminals, and advances in processing speed. The useof cloud computing has also progressed. In contrast
to the past model of centralized computer processing
on mainframes, devices and servers now interact witheach other to perform complex forms of processing.
Against this background, NTT business is undergoing a major transformation. Unlike the telephone erain which device and network services were provided
in an all-in-one manner, customers today use a variety
of services in combination. Here, the participation ofdiverse players has greatly broadened the choices
available to service users (Fig. 1).
In this type of era, what does it mean to be competitive? This is an era in which diverse ICT-based
services are provided by not only the communications industry but also other industries or businessareas, and users are able to freely select which services they would like to use. It is also easy for users
to switch to other services, which means that service
providers must make an effort not just to be selectedonce but also to be continuously selected. This ability
1

to be continuously selected as a service provider iswhat I believe to be the meaning of competitivenessfrom here on.
How can a service provider be continuously selected? In this era, it is extremely difficult for a single
company to meet the wide variety of user needs, so
collaborative ability, ability to initiate collaboration,
and ability to accept collaboration are important forbeing continuously selected.
2. Basic concept of medium-term
management strategy
In our medium-term management strategy
announced in May 2015, I stated that NTT would

Services

Services

Networks

Networks

Devices

Devices

All-in-one

Separatedby components

Cloud

1. Changes in the business environment

Fig. 1. Changes in the business environment.

NTT Technical Review

Feature Articles• Lifestyle transformations, solving social challenges• Business model transformation for service providers
B

B

X

NTT
Group

Serviceproviders

Members

Partners

AI, IoT,
VR, AR,
etc.

Viewers

Main
playersN(a ew sdd e
ed rviva ceslue)

Manufacturers
Shops

AR: augmented reality
VR: virtual reality

Fig. 2. Direction of initiatives for B2B2X model.

promote the business-to-business-to-X (B2B2X)
business model. Various predecessors of mine cameto create visions foreseeing the digital society of
today, such as the Information Network System(INS), Visual, Intelligent, and Personal (VI&P), Multimedia Vision, and Resonant Vision. In the past,when the plain old telephone service played a leadingrole, telecom companies were the main players inproviding services to customers directly. We have
now entered an era in which networks are selected not
as a single service but in combination with applications and services as a package. In this business environment, telecom companies are no longer the main
players but simply one option among many; that is,
we have become “one of them.” I declared, however,that we would be viewed as “one of them” with value.
With this in mind, we assigned the three lettersmaking up “NTT” to three key expressions: we let thefirst letter ‘N’ stand for Next Value Partner, the second letter ‘T’ for Transformation, and the last letter‘T’ for Trusted Solution. A major pillar of this medium-term management strategy was our own selftransformation to promote this new B2B2X model asa value partner that can help transform the businessmodels and lifestyles of a wide range of users.
3. Direction of initiatives for B2B2X model
I would like to see the creation of many kinds ofvalue for society through the B2B2X model. Moreover, I would like to see the creation of a new ecosystem based on collaboration with diverse partners. To
Vol. 15 No. 4 Apr. 2017

create new services and added value toward lifestyletransformations and resolving social issues, the NTT
Group will support service providers—the second ‘B’in B2B2X—in transforming their business models.
Here, the value that NTT can provide service providers can take various forms, such as artificial intelligence (AI), Internet of Things (IoT), and otheradvanced ICT technologies, user interface technologies, and security tools. I believe we can support thecreation of new value in this way.
The B2B2X model represents our transformationfrom one type of business model to another. In the
traditional model, the NTT Group provided services
directly to either individual or corporate consumers toincrease revenue. In the B2B2X model, we collaborate with diverse partners to deliver added value toconsumers through a wide range of service providers(Fig. 2).
4. Progress of B2B2X initiatives
In this section, I would like to introduce several
initiatives that represent our progress in promoting
the B2B2X model. In April and September of 2015,
we concluded respective comprehensive partnershipagreements with Fukuoka City and Sapporo City tohelp find solutions to key social issues enveloping
each of these cities. One example of the contributions
we have so far made to these cities is the use of Wi-Fi*
and other techniques to analyze the routes taken by*

Wi-Fi is a registered trademark of Wi-Fi Alliance.

2

Feature Articles

Establishment/operationof FIELD system
Support for implementationof FIELD system
NTT Communications

Development of applicationsof FIELD system
Providing advanced technology(edge computing)

NTT DATANTT

Fig. 3. Example 1 of B2B2X model.

inbound tourists, the places they go for sightseeing,
and what types of items they tend to purchase.
Moreover, since April 2016, we have been pursuingcollaborations with service providers and main players representing the second ‘B’ in B2B2X, such as
SHOCHIKU Co., Ltd., Kubota Corporation, and the
J.League (Japan’s professional soccer league). In thisarticle, I would like to describe, in particular, our collaborative efforts with FANUC CORPORATION,
SHOCHIKU, and Le Tour de France.

operation and application development (Fig. 3).
Combining AI and edge computing technologies inthis way enables distributed machine learning, while
performing real-time processing of the data collectedfrom machines at the edge (locations near machine
tools) enables these machines to cooperate with eachother in a flexible, immediate, and intelligent manner.
The goal here is to achieve advanced manufacturing
at a level not yet seen and to make them into a de facto
standard.

4.1 FANUC
FANUC is a global supplier of factory automation
and robot services. It aims to provide novel and smart
manufacturing sites by connecting various types ofmachine tools and devices used on manufacturing
floors to the network and by using the big data created by such connections in creative ways. This isachieved by the FANUC Intelligent Edge Link andDrive (FIELD) system.
Through collaborations with Preferred Networks,
Inc. and other partners, the NTT Group has supported
FANUC to develop and commercialize the FIELD
system by providing AI and edge computing technologies. In this effort, the NTT laboratories havebeen in charge of edge computing technologies,
while NTT Communications and NTT DATA haverespectively been handling system construction/

4.2 SHOCHIKU
I would like to introduce here our efforts in achieving a new way of enjoying kabuki performances
through collaboration with SHOCHIKU. In April
2016, the Niconico Chokaigi (super conference)sponsored by Dwango Co., Ltd. included a public
performance of “Cho Kabuki.” Through the use of theimmersive telepresence technology “Kirari!®” developed by NTT laboratories, the kabuki actor Shido
Nakamura appeared together with the vocaloid Hatsu­
ne Miku and also performed alongside duplicates ofhimself (doppelgangers) on stage (Fig. 4).
Niconico Chokaigi is a major event attended bymany young people. SHOCHIKU has said that it
would again like to present kabuki in new ways at
Niconico Chokaigi in 2017. It expects to attract newfans to kabuki and young people in particular by

3

NTT Technical Review

Feature Articles

Clockwise from top left: Poster of Cho Kabuki, performance of Cho Kabuki, poster ofkabuki in Las Vegas, and poster of Kabuki Virtual Theater

Fig. 4. Example 2 of B2B2X model.

adding a modern touch to traditional kabuki with newforms of ICT. I believe that an initiative of this typecan become a powerful weapon in expanding consumption, a key element of the Japanese economy.
In addition, in May 2016, stage greetings from thekabuki actor Somegoro Ichikawa, then in Las Vegas
as part of a kabuki performance, were transmitted inreal time to a remote showing at Haneda Airport. This
event included a question and answer session with
reporters just as if he were actually there standing infront of them. At the same time, some people at theevent were asked to put on a head-mounted display aspart of a virtual reality experiment that gave them thesensation of being inside the Las Vegas theater.
Furthermore, for two days on March 11 and 12,
2017, the Kumamoto prefectural government held a“Kabuki Virtual Theater” free to the public as part ofa “prayer for recovery” in the wake of the Kumamoto
earthquakes of 2016. Though a virtual performance, I
Vol. 15 No. 4 Apr. 2017

believed it enabled many people to enjoy a work
filled with a high sense of presence just as if Somegoro Ichikawa and other kabuki actors were performing right before their very eyes.
4.3 Le Tour de France
Dimension Data, a member of the NTT Group, hasformed a technology partnership with Le Tour deFrance, the greatest cycling race in the world. It provides a mechanism that identifies the speed and location of each rider by placing a sensor under the saddleof each bicycle and transmitting positional information to Dimension Data’s Big Data Truck (Fig. 5).
This information is used to create video that can bedelivered to televisions, smartphones, and otherdevices in real time. Spectators can then see for themselves how the riders are lining up in a completely
new and enjoyable way.
This mechanism not only represents an evolution in4

Feature Articles• Cycling speed• Location of riders

Big Data
Truck• Distance between riders

Fig. 5. Example 3 of B2B2X model.

the way that spectators enjoy Le Tour de France but
also an evolution in the way that team coaches andriders compete. In July 2016, I myself was in France
for Le Tour de France and heard a team coach comment that “I’m totally exhausted from all the data thatare now available for rider support!” In fact, it will
eventually become possible to deliver the vital signsof each rider by combining this mechanism withother types of devices. I think that the addition ofsuch information should enable the coach of a competing team to make more strategic decisions and toeven change training methods if necessary.
What I think all of us at NTT have in common is a
desire to support service providers and other players
representing the second ‘B’ in B2B2X in growing a
successful business. To promote consumption andeconomic growth, it is essential that the business ventures of main players, that is, service providers, aresuccessful. Providing support in this way should leadto our growth as well.
5. Further promotion of B2B2X model
I will now describe some important points for promoting the B2B2X model even further. Most important of all is coming up with a clear definition of ‘X’in B2B2X, that is, the service end users. Doing soshould bring into view a system of collaboration
between NTT and service providers and partners aswell as best business models, customer touch points,
etc.
Let me give some examples of this approach in the
5field of self-driving cars. What kind of interfaces
would be needed to enable the elderly and people
with mobility problems or disabilities to use selfdriving cars? No doubt, voice input and other types ofinterfaces would be needed. Moreover, in the case ofvoice input, some type of technology would be needed to ensure that the person’s voice was clearly understood in a noisy environment, and in Japan, there
would also be a need for technology that could identify different dialects. Here, instead of preparing
special interfaces for each and every car, a better
approach would be to develop cars that could support
the circumstances of individual users from the cloud
based on common specifications.
However, a self-driving car equipped with suchinterfaces and various types of safety equipment is
apt to be expensive. Plus, considering the frequency
of usage, the business model itself would not likely bea self-ownership type but rather a shared type. Whatkind of players would then be best for providing sucha service based on a shared type of business model? I
believe that local municipalities might make a positive contribution in this regard, and that local taxi
companies and public transportation systems mightteam up as second B players.
Here, it would not do for automobile manufacturersor NTT to play the role of service provider. I thinkthat supporting the provision of a new business modelor service as the first ‘B’ in B2B2X would be more
effective for speeding up the development of selfdriving technology.
In this way, instead of a product-out approach based
NTT Technical Review

Feature Articles

Super smart society• Collaboration in various fields with IoT technologies and creation of new value
throughout society• High degree of merging between cyberspace and physical space (real world)

1) Developing 11 systems

Energy value chain2) Building a common platform

Global environment
information platform

New manufacturingsystems

Intelligent transportation
systems
Integrated community
care systems

1.0

Hunter-gatherer
society

2.0
Agriculturalsociety

Maintenance andupgrade ofinfrastructure

Integrated material
development systems

Smart foodchain systems

Hospitality systems

Industrial
society

Smart production
systems

5.0

4.0

3.0

Resilient society
against natural disasters

Informationsociety

Super smart
societyFig. 6. Society 5.0 (The 5th Science and Technology Basic Plan).

only on technology, I believe, as I stated above, thatfinding a clear definition of ‘X’ in B2B2X, or in otherwords, defining what are new values or new sensations, will lead to new partners and new businessmodels.
6. Japan revitalization by Society 5.0
The Cabinet Office of the Government of Japan is
promoting the creation of a “super smart society”(Society 5.0) under the theme “New Initiatives
toward Japanese Industry of the Future and Social
Transformation” as The 5th Science and Technology
Basic Plan (Fig. 6).
The keyword “Society 5.0” signifies how society
has become progressively smarter through its transformation from a hunter-gatherer society to an agricultural society, industrial society, and informationsociety, and the coming super smart society. As abroad theme that includes Industry 4.0 (Fourth Industrial Revolution), I acknowledge that Society 5.0 is
precisely the next big concept that Japan should adopt
in future policy making.
In response to this Cabinet Office policy, the Japan
Business Federation (Keidanren) has begun its impleVol. 15 No. 4 Apr. 2017

mentation by drafting an action plan based on key
subthemes underlying Society 5.0 [1].
Specifically, a future society as envisioned by
Keidanren can be broken down into five subthemes: asmart society undaunted by the decrease in population; a society in which every individual, including
elderly people and women, can actively participate; asafe and secure society in both cyber and physicalspaces; a society that connects cities and outlying
regions, making for a comfortable and pleasant life
anywhere; and an environmentally and economicallysustainable society. In addition, cities, regions,objects/things/services, infrastructure, and cyberspace have been designated as specific study areas.
In this way, the government and Keidanren, that is,
the public and private sectors, are promoting Society
5.0 with the aim of building the society of the future.
Here, AI, big data, and IoT will play important roles
in making Society 5.0 a reality. IoT will enable a wide
variety of real-world data to be stored as big data, andAI will enable that data to be analyzed, so we can
expect a wide range of social and global issues to besolved in this way. However, such social issues cannot be solved if companies and local municipalities
keep their data to themselves. It is essential that all
6

Feature Articles

Supporting the improvement of administrative services
B

B

X

NTT
Group

ServiceproviderResidents

Local
municipality
Partners

Tourists

Local
companies

Fig. 7. Data sharing with local municipality as hub.

data in society be shared across industries and fields.
7. Concerns in data usage
A key issue in the use of data throughout society is
the handling of personal data. Who does personal
data belong to? Do you, the individual, own it? Ordoes it belong to the companies that gather the data?
The EU approved the right to data portability in
April 2016. In Europe, legislation is moving forward
to enable individuals to retrieve their personal data—
for example, a purchasing history gathered by Google
or Apple—and to transfer that data to other business
operators if so desired. In Japan as well, the handlingof personal data is a very sensitive issue, and I think
there is a need here to proceed carefully.
Rather than obsessing about the ownership of personal data, I have proposed to various parties theconcept of treating various types of data as belonging
to society and citizens.
With an eye to appropriate handling of such sensitive information, the NTT laboratories have beendeveloping secret-sharing and secure multi-party
computation technology. This technology securely
stores personal data through encryption and distributed storage, and at the time of data analysis, enables
only the results of analysis to be obtained without
data analysts having to touch the raw data. We areusing this technology in initiatives that aim toadvance the use of big data throughout Japan.
There are also other issues in addition to the handling of personal data that must be resolved toachieve data sharing and data usage throughout society. First, there is a need for widespread gathering of
good-quality data. I believe that the biggest risk in the
AI and big data society of today is that smart AI will
7

routinely process malicious or intentionally erroneous data. For example, traffic signals may behave inan abnormal manner on the basis of erroneous data,and control equipment in a power plant may automatically stop if it detects something it considers to
be dangerous. The widespread gathering of goodquality data will require security technology that canremove such erroneous data. It will also be necessary
to ensure fair usage in data gathering. What exactly is“fair usage?” As I explained earlier, data gathering to
improve community services and solve social problems is a fair objective. Of course, there is a need forencryption to protect personal data and a check system to prevent abuse. I also think that the standardization of data formats and ciphers is necessary.
8. Data sharing with local municipality as hub
I believe that one method of resolving these data
sharing and usage issues is to promote the gathering
and use of big data with local municipalities serving
as hubs. Considering the need for combining andhandling a wide variety of data to solve social issues,
I think there would be a problem allowing a single
company to gather and use such information.
In particular, I believe that opening up the data heldby a local municipality, such as demographics, maps,
disaster prevention measures, and sightseeing information, and providing the big data held by companies
to industry as public property can expand possibilities
in the integrated use of all kinds of data and revitalize
local business.
The concept of a local municipality serving as aservice provider to improve community services isshown in Fig. 7.
The NTT Group, working with partners such as
NTT Technical Review

Feature Articles

Edge computing technology
FANUC

IoT platform
IoT data exchange technology
Immersive telepresence “Kirari!® ”

Cho Kabuki
Kabuki in Las Vegas
Henshin Kabuki
Kabuki Virtual Theater

Light projection technique “HenGenTou”

SAP

Transportation safety solution

Wearable vital sensing fabric “hitoe”

KUBOTAICT solutions for agriculture
and water infrastructure

AI-related technologies “corevo® ”

Localmunicipalities

Regional revitalization throughdata sharing and usage

SHOCHIKU

Angle-free object search

Secure computation system
Anonymization technology

Fig. 8. Technologies underlying B2B2X model.

Panasonic Corporation and Hitachi, Ltd., would liketo provide local municipalities with support tools. We
would like to see local municipalities take on a leadership role in data sharing and data usage within theircommunities with the aim of improving community
services and expanding local business, as I just mentioned. Although we are talking about local municipalities here, we know that undertaking this initiative
simultaneously throughout the country would bequite difficult from an operations point of view. We
have so far concluded agreements with Sapporo Cityand Fukuoka City to get this initiative started.
I would like to see this initiative with local municipalities evolve so that they shift to the first ‘B’ in
B2B2X while local industries and companies act as
the second ‘B.’ In this way, I would like local municipalities, NTT, and other players to become partners
in supporting local industries and contributing to the
expansion of local economies. I see this type of activity as another major theme in Japan that can lead toVol. 15 No. 4 Apr. 2017

regional revitalization.
9. Technologies underlying B2B2X model
Finally, examples of technologies that NTT laboratories and NTT Group companies are providing toservice providers and other players making up thesecond ‘B’ in B2B2X are shown in Fig. 8.
Going forward, the NTT Group will continue topursue collaboration with diverse partners to generate
new value and new sensations, help grow the Japanese economy, and help find solutions to a wide variety of social issues.
Reference[1]

Keidanren, “Toward Realization of the New Economy and Society Reform of the Economy and Society by the Deepening of ‘Society
5.0’-,” 2016.
https://www.keidanren.or.jp/en/policy/2016/029_outline.pdf

8Feature Articles: Keynote Speeches at NTT R&D
Forum 2017

NTT Research and Development—
Leading the Way to B2B2X
Hiromichi Shinohara
Senior Executive Vice President and Head of Researchand Development Strategy Department, NTT
Overview

This article introduces NTT’s research and development (R&D) activities for creating new value through collaboration with various partners topromote the B2B2X (business-to-business-to-X) business model under
the NTT Group’s medium-term management strategy, Towards the Next
Stage 2.0. It is based on a lecture presented by Hiromichi Shinohara, NTT
Senior Executive Vice President and Head of the Research and Development Strategy Department, at NTT R&D Forum 2017, which was held in
February 2017.
Keywords: B2B2X, artificial intelligence, Internet of Things

1. Expansion of B2B2X model and roles of R&D
We believe that research and development (R&D)
serves as an engine for driving the business-to-business-to-X (B2B2X) business model. This is because
propelling innovation is the foundation of our ability
to provide new value to service providers (the second
B in B2B2X) and consumers and enterprises (X). On
the basis of this understanding, the NTT R&D laboratories (hereinafter, NTT R&D) is pursuing coinnovation with various partners. This effort, over thelast two years, has shown us that collaboration, especially with partners in unrelated industries, can generate hitherto unimagined concepts, so we are currently
focusing on that type of collaboration (Fig. 1). While
network, security, and cloud technologies are naturally important for driving B2B2X, this article focuses on artificial intelligence (AI), the Internet ofThings (IoT), and media technology.
2. NTT Group’s AI technology: corevo®
AI can be approached in two different ways. One is1

to simulate human intelligence and thinking. The
other is to supplement and draw forth human ability.
NTT R&D is working on the latter, namely, AI thatcreates new value through coexistence and co-creation with humans.
In the spring of 2016, the NTT Group unified thegroup’s AI-related activities under the brand namecorevo®. It signifies our wish to bring about new,revolutionary developments in collaboration with avariety of players (co-revolution) by integrating different types of AI technology. Specifically, our R&D
is focused on four categories of AI (Fig. 2).
Agent-AI is closest to the AI that is presently making news. It supports humans by interpreting theinformation that they generate. For example, AgentAI makes it possible for a robot to conduct an intelligent conversation with humans. Ambient-AI interprets humans, objects, and the environment, andinstantly forecasts and controls the immediate future.
In this sense, it embraces the concept of IoT. HeartTouching-AI interprets human emotions and physicalconditions and understands our deep psyche, intellect, and instinct so that it can see things from a
NTT Technical Review

Feature Articles

B

X

Serviceproviders

Consumers

NTT EAST
NTT WESTNTT
Communications

Collaboration withother industries

NTT DOCOMO

Create new value

B

Companies

NTT DATA

Co-innovation

Partners(Open communities
etc.)

Fig. 1. Expansion of B2B2X model and roles of R&D.

Corevo: Co-revolution
Creating revolution with a varietyof players
corevo webpage (in Japanese):
http://www.ntt.co.jp/corevo/

Agent-AI
Supports humans by interpreting the information they generate
Ambient-AI
Interprets humans, objects, and the environment, and forecasts
and controls the immediate future instantly
Heart-Touching-AI
Interprets human emotions and physical conditions, andunderstands the deep psyche, intellect, and instinct
Network-AI• Connects different types of AI into collective intelligence andoptimizes the social system as a whole• AI applications to networks

Fig. 2. NTT Group’s AI Technology: corevo®.

human perspective. Network-AI embraces two concepts. One is to connect different types of AI intocollective intelligence and optimize the social system
as a whole. The other is to apply AI to networks inorder to enhance their reliability, efficiency, and otherqualities.
2.1 Agent-AI technologies
Agent-AI is founded on three types of technology:
Vol. 15 No. 4 Apr. 2017

auditory technologies; speaking technologies, which
include the capacity to understand speech; and viewing technologies. Representative technologies arepresented below.
(1) Auditory technologies
One auditory technology is noise suppression. This
makes it possible to hear a human voice clearly, evenin an environment filled with noise and cheering to alevel of more than 100 dB. Speaker diarization2

Feature Articles

EnglishKorean

Malay

Thai

VietnameseIndonesian

Mandarin
ChineseJapanese

Taiwanese
Cantonese(Hong Kong)

Supports 10 languages

Japanese English etc.
Supports dialects:• Kansai, Tohoku dialects, etc.

Fig. 3. Language-identified speech recognition.

technology allows the user to identify a speaker fromamong many people speaking simultaneously. Currently, one speaker can be identified from among up
to six people talking at the same time. If this technology is used inside a vehicle, for example, the user canlisten to the voice of just the driver.
In the CHiME-3 (the 3rd CHiME Speech Separation and Recognition Challenge), an international
technical evaluation contest in which participatingorganizations competed in speech recognition in avariety of noisy environments, NTT’s distortionlessspeech enhancement and deep-learning speech recognition technology achieved a speech recognition
rate of 94.2%, the highest in the contest. Languageidentified speech recognition has been developed
based on this technology. Currently, it identifies andrecognizes speech in ten different languages (Fig. 3).
It can even recognize the type of English typicallyspoken by Japanese people, and its coverage of representative Japanese dialects is being expanded.
Frequently asked question (FAQ) search is often
employed when AI is used to answer questions. One
challenge is that different people ask the same question using different expressions. AI must accurately
understand which question in the FAQ list the questioner is referring to. NTT R&D’s utterance comprehension technology understands questions accurately,
thanks to its machine learning that utilizes a text corpus containing extremely diverse expressions and alarge-scale semantic dictionary that has been enrichedover a long period.
We are also working on emotion recognition tech3

nology. This determines, for example, if a person isangry, satisfied, or worried from the way he or she
speaks. In addition to hot anger characterized byshouting, this technology can identify the more subtle
cold anger, which is characterized by the speakersounding calm but being angry inside, an attitude said
to be very common in Japanese people.
(2) Speaking technologies
We are studying technology that automatically constructs intonation information of a speech using deeplearning (Fig. 4). AI needs to differentiate words thathave the same sounds but different accents and meaning, such as “haSHI” (bridge) and “HAshi” (chopsticks) in Japanese, or the noun “object” ( bd ikt)
and the verb “object” ( bd ékt) in English. The aim of
this technology is similar to that of the emotion recognition technology mentioned above. It is intended
to help the user to communicate in a manner that is
appropriate for the occasion, for example, speaking tosomeone in trouble in a sympathetic manner or
speaking to an angry person in a soothing manner.
This technology can efficiently construct prosodic
information.
Free dialog technology is aimed at enabling AI not
only to answer questions but also to conduct a freeconversation. In March 2016, at SXSW (South bySouthwest), a major business and content event heldin Austin, Texas, an android built by Professor Hiroshi Ishiguro of Osaka University called “Geminoid”
had a conversation with a woman, a total stranger tothe android. This was made possible by incorporating
our speech and dialog-related technologies into the
NTT Technical Review

Feature Articles

ObjectProsodic analysis DNN(deep neural network)

Prior learning phase

This isa ....

objectRead + prosodic information

Speechsynthesis

This isa ....

Conventional:
Costly and hard to make or get
Prosody*

Text
Large volume of data
Voice and text
Learning data
*Accent, tone, intonation, etc.

Fig.4. Automatic acquisition of prosodic information using deep learning.

android. We will seek to enable robots to performsomething more challenging, such as carrying out adebate or improvising amusing dialog.
(3) Viewing technologies
We humans recognize an object by comparing what
we see with what we have in our memory. Angle-freeobject search technology does just that. It searches
images previously registered in a cloud for the object
captured by a smartphone camera. Its forte is that it
can recognize an object even if only one or two photos are pre-registered and even if the object is captured from an oblique angle or in close-up, or part ofthe object is obscured by someone standing in frontof it.
We are studying video event detection technology,
which searches for a video showing a scene of eating
or a scene of driving a car, for example. At TRECVID
2016, a worldwide workshop hosted by the U.S.
National Institute of Standards and Technology, NTT
R&D won first to third places in several categories
with this technology.
2.2 Application examples of Agent-AI
Using Agent-AI technologies, NTT Communications has initiated a commercial service using Communication Engine COTOHATM. This service understands natural language and answers questions fromVol. 15 No. 4 Apr. 2017users. If the question is vague, the engine attempts tounderstand what the user wants by asking specificquestions for clarification. If it determines that it stillcannot understand the question, it transfers the question to a human operator and learns from the way inwhich the operator interacts with the user.
In addition to introducing individual technologies,
we are holding concept exhibits such as corevo for
drivers and corevo for service desks so that people
can get some idea of specific situations in which
corevo technologies can be used.
2.3 Support for robots and sensors
A variety of services can be created by combininga group of some of the AI technologies mentioned
above with robots and sensors. With a view toenabling customers to create their own services using
our AI technologies, rather than leaving service creation to professionals, we have developed R-env®, acloud-based human-machine interaction control. It
provides a mechanism whereby the user can quickly
construct a program using a web browser. NTT
EAST, NTT WEST, NTT Communications, and NTT
DOCOMO are conducting joint field trials on potential applications for medical care or invigoration of
local economies. The trials have already yieldedsome practical services.
4

Feature Articles

Statistical processing

Ambient-AI

Analysis task design• Understanding users• Hypothesizing

Detection technologies
Anomaly sound detection

Machine learning

Movement state estimation
Data cleansing
Change-point detection
Optimal example detection from
unbalanced learning data

Data

Humans,objects,
Analysis model optimization
environmenty = a1x1 + a2x2 + … + e • ModelingX+• Hypothesizing testing
P1 Y

Deep learning

Forecasting technologies
Real-time mobile demand forecasting
Large-scale graph mining

P2±

Data preprocessing fordetection and forecastingFig. 5. Ambient-AI.

2.4 Ambient-AI technologies
Some of the Ambient-AI technologies being developed by NTT R&D are described below. These days,
we frequently hear terms such as machine learningand deep learning. These are also utilized in AgentAI. The most important factor in using machinelearning, deep learning, or statistical processing tools
is to optimize the analysis model used. How good or
bad your analysis model is determines the value of
your data. For instance, it has a significant impact on
detection or forecasting performance. Thus, we are
optimizing analysis models used by detection andforecasting technologies (Fig. 5).
We are developing technology that can quickly
detect significant differences between two satellites oraerial photos of the same area taken at different times.
It does so by measuring the difference in information
quantity, called entropy, at each pixel after the photos
are compressed using the video encoding applied to
4K and 8K. Currently, the rate of successful detectionof change-points is about 90%, indicating that there is
still room for improvement. We will conduct a fieldtrial during this fiscal year with NTT GEOSPACE.
We are studying technology for learning with ahigh degree of accuracy just the relevant data fromamong a group of data of which only an extremely
small fraction is relevant (Fig. 6). In collaboration
5

with the Japan Science and Technology Agency, theUniversity of Tokyo, Tsukuba University, and theInstitute of Statistical Mathematics, we are using thistechnology to zero in on supernovae from among ahuge collection of space photos taken with the Subaru
telescope. The number of pixels comprising thesephotos is on the order of several tens of trillions.
Although only 1 in 1000 novae in the learning data is
a supernova, this technology has reduced the observation time required to detect supernovae by a factor ofseveral hundred compared to that of the conventional
method. We next tried to discover Ia-type supernovae
and found the first one at the end of 2016. Ultimately,
we will try to use machine learning to estimate theparameters of the equation that determines the fate of
the universe. Our aim is not exactly to decipher theuniverse but, rather, to refine our technologies
through these activities.
2.5 Application examples of Ambient-AI
Some commercial applications of Ambient-AI
technologies are described below.
(1) Detection of advance signs of machine failures
A technology that NTT DATA has jointly developed with Hitachi Zosen Corporation focuses onmachine operation sounds in order to support stable
operation of factories. It detects glitches and advanceNTT Technical Review

Feature Articles

Zero in on supernova
Subaru HSC(Hyper Suprime-Cam)
Machine learning
Japan Science and Technology
Agency, the University of Tokyo,
Tsukuba University, and theInstitute of Statistical Mathematics

Subaru telescope

Captured space data(tens of trillions of pixels)

Optimal example extraction
from unbalanced learning data

Discovers Ia-type supernova*
Automatic detection
using deep learning

About 1 out of 1000 novae in learning
data is a supernova.
Learn with a high level of accuracy
from a small number of examples.

Estimates cosmologicalparameters
Efficient cosmological parameter
estimation using machine learning

Observation time is reduced to
one several hundredth the time of
the conventional method.

Deciphers the universe

Equation that determines the fate of
the universe
8 G
Rµ v − 1 gµvR + gµv Λ =c 4 Tµv
2*One of the subcategories of supernovae and cataclysmic variable stars

Fig. 6. Detection technology.

signs of failures using intelligent microphone technology, which picks up target sounds clearly even in
noisy environments, and technology that distinguishes between normal and abnormal sounds.
(2) Detection of dangerous driving behavior
This technology detects dangerous driving of a carby analyzing multimodal information in video datastored in a drive recorder, and sensor data such as
speed and acceleration information. In a trial jointly
conducted by NTT Communications and Nippon Car
Solutions Co., Ltd., dangerous driving was detectedwith about 85% accuracy. The information gained
will be used for educating drivers and formulating
measures to reduce accidents.
(3) Congestion forecasting
NTT DATA is seeking to help reduce traffic congestion by visualizing congested conditions and predicting imminent jams. This is achieved by applying
large-scale graph mining to data from beacons andtraffic information in text form. Field trials are being
carried out in China, and another is planned for theVol. 15 No. 4 Apr. 2017

UK.
(4) Taxi demand forecasting
We are also using AI to combine and analyze a variety of information ranging from taxi operation data
through demographic data, weather data, and event
data, in an attempt to forecast areas that will see large
taxi demand 30 minutes ahead. Allocating taxis basedon such forecasting could boost taxi company sales
and reduce waiting times for taxi users. NTT DOCOMO is conducting joint field trials with the Tokyo
Musen Cooperative Association and Tsubame Taxi
Group in Nagoya (Fig. 7).
2.6 Network-AI technologies
One category of Network-AI is application of AI to
networks. We are working on technologies for detecting faulty parts in a network with a high degree of
accuracy, for forecasting communication traffic by
area, such as urban areas and residential areas, and forrouting traffic to avoid faulty or congested points, ifany. The other category of Network-AI is connecting
6

Feature Articles

Collect and accumulate

Forecast

Control

Real-time mobile demand forecasting
Forecasts demand 30 minutes from now
Operation data
Mo

ve

ba

Area with high demand forecast
30 minutes from nowse

Demographic data

do

nf

or

ec

Ratio of loading trips
to total tripsas

Low demandtWeather data

Medium demand

ca
s
re
fo
se

Excellent
driverMediocredriver

Alternative means

do

d

se

on

ba

Congestion
Delay

st

ca

M

ov

ore

e

nf

ba

Increase
efficiency

Reduce waiting timeve

Facility dataMotHigh demand

Event data

Boost sales
by improving utilization rate

Accident

Optimal placement for drivers
Tokyo Musen Cooperative Association

Tsubame Taxi Group (Nagoya)

NTT DOCOMO

Fig. 7. Taxi demand forecasting.

different types of AI in order to achieve global optimization of a system. In collaboration with the Japan
Agency for Marine-Earth Science and Technology,
we are developing technology for combining widearea simulation with local area-specific processing inorder to improve the accuracy of weather forecasting.
2.7 Heart-Touching-AI technologies
We have recently initiated new activities in the fieldof sports brain science. According to specialists,
physical performance is affected not only by physicalconditions but also by the brain. The objectives of ouractivities are to elucidate brain mechanisms and tocreate effective training methodologies that can beused in the field.
3. IoT targeted by NTT R&D
The IoT world is aimed at creating new value bycollecting data from various things in society, visualizing them, and analyzing them using AI technologies. NTT R&D is focusing on the following four IoT
requirements.
7

First, for data collection, sensors need to permeate
humans and objects naturally. Second, while somedata processing, such as that for paddy field management in agriculture, has no time constraints, dataprocessing for operation of machinery in factories
must be carried out in real time in order to minimize
delay. Third, for value creation, a mashup of diverse
types of data is important. Lastly, a common requirement is secure handling of data.
3.1 IoT basic architecture
In line with these requirements, NTT R&D uses thefollowing IoT basic architecture (Fig. 8).
If we are to promote circulation of information, thearchitecture needs to embrace the following parts: 1)
an IoT gateway that unifies, at the entrance, communications standards that vary from industry to industry; 2) IoT data exchange that standardizes data formats and distributes data to different analysis functions; 3) software components and high-speed distributed processing needed to optimize data analysis
performance; 4) library middleware and applications
for turning data into value; and 5) management of the
NTT Technical Review

Feature Articles

External systems
Integrated security
management

Applications
Library middleware

Management

Advanced distributed processing
Software components
Linux

IoT data exchange

Security orchestration

NMTF

Security gateway
IoT gateway
Network (wireline/wireless)IoT device security
Devices and sensors
NMTF: Non-negative Multiple Tensor Factorization

Fig. 8. IoT basic architecture.

entire operation. Furthermore, the following security
measures should be added to the architecture: 6) IoT
device security for protecting information at the communication layer; 7) a security gateway for detecting
and blocking malicious data at the receiving points;
and 8) integrated security management and security
orchestration for detecting abnormalities in a system
as a whole and immediately applying blocking rules.
We are developing functional units that implement
NTT R&D technologies in the IoT basic architecture.
We are also studying which of these functional units
should be used in combination for a specific application area or usage, and how to allocate these functional units among clouds, edges near devices, andgateways if we wish to reduce delay or achieve compact packaging.
3.2 Sensing
In collaboration with Toray Industries, Inc., wehave developed “hitoe,” a sensing fabric that canmeasure cardiograms and electromyograms. In addition to using the fabric to simply collect data, we havebegun to study how to identify fatigue, heat stroke,
and the user’s mental state from a cardiogram, andhow to determine muscle fatigue and lactate threshVol. 15 No. 4 Apr. 2017

old from an electromyogram. For example, “hitoe” isused to estimate the fatigue level of long-distance bus
drivers and to determine if outdoor workers are suffering from heat stroke. NTT WEST is employing“hitoe” to visualize the mental states of golfers.
Formerly, we were able to claim only that “hitoe”
could measure heart rate. Since registering “hitoe” asa general medical device in August 2016 (Fig. 9), we
have been permitted to state that the fabric can measure a cardiogram. Today, it is used in many hospitals.
We are conducting a joint field trial with Fujita
Health University to study how “hitoe” can be used toreduce the duration of hospitalization for patients
undergoing rehabilitation.
We are also applying the fabric in professional
sports. In the Indy 500 in the United States, NTT
DATA uses “hitoe” to monitor the physical loads on
racecar drivers in the extremely demanding environment. In bicycle races, “hitoe” is used to visualize not
only road racers’ heart rates, speeds, and rotations but
also their reserves of physical strength.
3.3 Application examples of IoT
Examples of the use of NTT R&D’s IoT technologies are presented below.
8Feature Articles

Registered as a general medical device in Japan
Medical electrode• Non-irritant• Does not restrict movement• Continuous measurement

Singletime use
Electrodeside

Back side

Medical lead wire
Enhanced
detection ofillnessFig. 9. Applications of “hitoe.”(1) Support for vehicle operation
IoT technologies can support vehicle operation by
estimating the fatigue levels of bus or truck drivers
and recommending rest when a certain level offatigue is suspected. In a field trial on a highway,
conducted jointly with Keifuku Bus, data on thedriver’s fatigue level were visualized. The data
showed that after the start of the drive, the fatigue
level increases gradually and that after resting at a
service area, the driver recovers from the fatigue.
Following this field trial, NTT Communications
launched a service that supports vehicle operation. In
addition to “hitoe” being used to obtain bioelectrical
data, NTT R&D’s high-speed distributed processing
plays a critical role in processing streaming data suchas heart rate data in real time.
(2)	Optimization of manufacturing/production in afactory
With a view to innovating manufacturing, we are
seeking to raise production efficiency by getting various machine tools in a factory to work in coordination
and by processing the data involved in real time
(Fig. 10). A key to achieving this real-time processing
is edge computing, in which the necessary processing
functions are allocated at edges near the machine
tools rather than in clouds. We have combined edge
computing with an IoT data exchange function,
which circulates information handled by various
types of machine tools in the form of common data,
and with a software component management function, which flexibly selects application programs
according to the particular usage of machine tools ina factory. We are working with FANUC CORPORATION toward its planned launch of a service inautumn this year.
(3) Improvement of farming productivity
9

The NTT Group is collaborating with Kubota Corporation to improve productivity and competitivenessin agriculture by combining NTT R&D’s technologies with NTT GEOSPACE’s map data, which are
NTT assets, Halex’s weather data, and JSOL’s yield
forecast data.
3.4 Security
An important consideration in promoting IoT issecurity. The IoT environment is characterized by aninability to execute complex processing due to limited processor power.
Our next-generation passwordless authentication
technology does not require servers to manage information needed for authentication (Fig. 11). The user
can securely authenticate an IoT device with only twoitems of information: a device identification and an
item of secret information held in the IoT device. The
server does not hold authentication information foreach device. This technology has been developed andreleased as open source software. As a future application, we are studying the possibility of using thistechnology to prevent spoofing of IoT devices. For
example, when a genuine home delivery drone and afake home delivery drone arrive, it will be possible toauthenticate only the real one.
We are researching technology for lightweightencryption, which is secure and does not impose aheavy processing load. It is important to confirm thatthe encrypted information will not be broken. We doso by creating encryption analysis methods ourselvesand checking resistance to new attacks. We recently
developed a new encryption analysis method called anonlinear invariant attack and proved that some existing lightweight encryption systems are vulnerable.
We are also studying how to strengthen the security
NTT Technical Review

Feature Articles

Requirements

Don’t want to reduce operational time
Want to improve productivity

Detects/forecasts
facility failures

Service to be started
next autumn

FANUC

NTT DATA

Software component management

Application

Real time• Integrated operation ofmultiple devices

Open• Change/update functions

Edge computing

FIELD system
Open platform

IoT data exchange

NTT

NTT Communications

Global ICT

Operational
data

Enhancing factory
productivity

Devices/sensors

Connective• Connection to various devices

ICT: information and communication technology

Fig. 10. Optimization of manufacturing/production in a factory.

of a system as a whole, especially critical infrastructure, in addition to the security of individual IoT
devices. Cyber-attacks aimed at disrupting criticalinfrastructure can produce serious consequences.
With Mitsubishi Heavy Industries, Ltd., we are jointly developing a system that determines the operating
mode of a certain infrastructure from data collectedfrom sensors, detects abnormalities, and restores theinfrastructure. We are studying a way to minimize
damage from novel cyber-attacks by combining security gateways, analysis applications, and security
orchestration.
4. Visualizing the near future and beyond
Looking to 2020 and the creation of lasting assets,
we believe that NTT should play three roles: providing stable high-quality network services, implementing reliable network security measures, and providing
hospitality, deep positive impressions, and new expeVol. 15 No. 4 Apr. 2017riences to visitors. This article focuses on our activities in respect to the third role.
4.1 Hospitality
We have initiated a number of trials aimed at providing services for international tourists, who continue to increase in number. In field trials underway
at a Tokyo Metro subway station and at Nissan Stadium, angle-free object search technology, mentioned
above, and 2.5-dimensional (2.5D) map representation technology are used to provide intuitive navigation (Fig. 12). When a tourist points a smartphone at
an information sticker pasted in a Tokyo Metro station, his/her current location is detected without any
need for beacons. When the user inputs his/her destination information, a 2.5D map, which is a 2D mapwith height information added, is displayed on his/her smartphone so that he/she can easily find the way
to the destination. In the field trial at Nissan Stadium,
navigation using an accessibility map is also provided.
10

Feature Articles

Authentication server

IoT device
New authentication
protocolAuthentication client/application
DeviceID

Encryption

Authentication
information foreach IoT device
is not needed.

Authentication request

Any operating
systemConventional method:
authentication
information for eachdevice is needed.

Highly complex
encryption is
executed at highspeed.

Secretinformation foreach device

Released as OSS

MilagroOK

Future application
Prevents spoofing
between IoT devices

Genuinedeliverydrone

Malicious
delivery drone

Delivery box
Not OK

ID: identification
OSS: open source software

Fig. 11. Next-generation passwordless authentication.

2.5D map representation
Paths to a destination not visible
from the current location are displayed.

Navigation to Exit A2

Field trial in progress

Intuitive
Smart
2D + height
Omotesando platform
2.5D representation

Angle-free object search

Omotesando Station,
Tokyo Metro
Field trial in progress

The user can determine his/her current
location and direction by pointing asmartphone at a signboard.
Nissan StadiumFig. 12. Navigation for international tourists.

For example, when the system learns that a person isin a wheelchair, it provides navigation specificallydesigned for wheelchair-bound persons.
In the field trial at the Tokyo Metro subway station,
11

angle-free object search technology is used to direct
passers-by using advertisements on walls. For example, when a person points a smartphone at an advertisement on a wall, he/she receives a coupon for a
NTT Technical Review

Feature Articles

Web information

SimpleDisaster, tourism sites

Content forwebsiteContent for signage
Multi-lingual signage
multicast system

Web information is automaticallyconverted into signage information
in a timely manner.
To any target areas

Trial being conducted in
Takeshiba, Minato-ku,
Tokyo

Reliable
Multicast is maintained
locally in the event ofa wide-area disaster.

Multicast across different systems

To anyone
Information is automaticallydisplayed in the language
normally used in thesmartphone.

LocalsystemWi-Fi
Municipality facilities

Subwaystations

Shoppingmalls

Restaurants

Smartphone

Fig. 13. Multicast of multi-lingual information on signage.

special offer as well as information on how to navigate to the shop concerned. This will be especiallyconvenient for overseas visitors.
In a field trial conducted in Takeshiba, Minato-ku,
in Tokyo, emergency information is multicast to various signage systems in the event of a disaster(Fig. 13). It is vital to ensure that information that has
been multicast to signage units dispersed through atown is definitely displayed, irrespective of the sign
owners or the types of signage units. We have developed a multi-lingual multicast system that multicasts
information to different signage systems and directs
those systems to send information to the smartphonesof passers-by in such a way that the information is
automatically displayed in the language used in thesmartphone. The objective is to enable overseas visitors to promptly receive emergency information in
the event of a disaster.
In the retail and distribution fields, NTT and Seven& i Holdings Co., Ltd. are carrying out a joint fieldtrial in which overseas visitors can easily get productinformation using smartphones. For example, when aperson points a smartphone at a rice ball, he/she canVol. 15 No. 4 Apr. 2017

immediately get information on the ingredients andallergic substances contained in the rice ball—currently, in any of 15 languages.
With a view to providing ease of use, we havedeveloped a see-through device in collaboration with
Panasonic Corporation (Fig. 14). Since the device is
not as powerful as a smartphone, its operation is
assisted by edge computing technology. When it ispointed at an object, it displays information aboutthat object. It uses the latest transparent color display
from Japan Display Inc. Widespread use of thesetechnologies will expand the industry in Japan.
Since last year, we have been holding R&D ForumShowcase to enable visitors to the forum to havehands-on experience with our R&D technologies. In
this event, visitors can try our official app. It recommends a route to an individual user based on his/herinterests and the current distribution of people on thefloor, and answers questions about recommended
exhibits using AI. When the user points a smartphone
at an exhibited panel, the “point and get information”
function of the app displays information relating tothat exhibit. Information is shown in English if the12Feature Articles

Fig. 14. See-through device.

user is from overseas.
4.2 D eep positive impressions and new experiences
The immersive telepresence technology called“Kirari!®” has been exhibited at NTT R&D Forum
since 2015, when images of people were extracted
from a recorded video and displayed in quasi-3D. In
2016, images of people were extracted from a video
in real time for the first time during my keynote
address. In 2017, we attempted a more challenging
undertaking of extracting images of people from awider area in a higher-definition video.
We have been experimenting with convergence of
information and communication technology (ICT)and kabuki, a Japanese traditional performing art. At
the Niconico Chokaigi (super conference) held in
April 2016, “Cho Kabuki” was presented. This wasfollowed by a performance of “KABUKI LION SHISHI-O” produced by SHOCHIKU Co., Ltd. in Las
Vegas, in May. In March 2017, “Virtual Kabuki Theater” was staged in Kumamoto. The latest object
extraction technology has been used to display the“swinging of head hair” by a kabuki actor. Details of
his whirling hair were extracted and displayed clearlyand naturally.
We will continue to improve Kirari!. Next year, we
will develop technology for projecting a 3D image insuch a way that it can be viewed from an arenashaped spectator area. In other words, the image will
be viewed not just from one direction but from all
directions.
4.3 Convergence of sports and ICT
We are using ICT to assist the training of athletes
and to captivate fans by giving them deep, positive
13

experiences of sports events.
Our efforts to help train athletes target both endurance-type sports such as swimming and cycling, andinstantaneous and interpersonal sports such as baseball and badminton. For the latter, we are elucidating
brain functions of athletes by collecting data fromformer professional baseball players and members ofuniversity baseball teams. For the former, we are
studying analysis of heart rates and myoelectric
information on swimmers because it has become
technically possible to use the sensing fabric “hitoe”
for underwater monitoring.
We are studying the use of virtual reality to offer
new experiences in watching sports events. We havedeveloped athlete first-person vision synthesis technology. This was initially targeted at baseball. It synthesizes a real baseball park video and a CG (computer graphics)-reproduced baseball so precisely thatthe user can view the ball and the park from any viewpoint, for example, from the position in the right batter’s box or from the position of the catcher. Our
objective was to enable children to experience fastballs pitched by top players. However, systems that
implement this technology are now also used by professional baseball teams for training.
We have expanded the application of this technology to other types of sports. For example, the user canexperience a free kick by a soccer player or a drop
shot serve by Kei Nishikori, a Japanese tennis player
with whom we have concluded a sponsorship contract. Conveying the amazing skills of top athletes tochildren—the next generation of players—will help
to expand sports-related business.
5. Conclusion
Although I have mainly introduced applied technologies in this article, we are also committed tobasic research, knowing that the various AI technologies in our hands today have been built on the resultsof our past basic R&D spanning several decades. The
lesson is that we should not confine ourselves to
R&D of technologies that are useful today. We mustalso pursue basic R&D that may become applicable
five or ten years from now.
Let me introduce two types of basic research. We
have developed a new quantum computing principlethat uses light to rapidly solve difficult mathematicalproblems that cannot be cracked using today’s supercomputers. This was published in Science, a U.S.
scientific journal. In the quantum world, there is arealism problem whereby the state cannot be
NTT Technical Review

Feature Articles

determined before the time of observation. There has
been intensive argument as to whether this is true
only in the quantum world or also holds in the realworld or in the macroscopic world. We have proventhat breaking of realism occurs even in the macroscopic world. This was released in Nature Communications, a UK scientific journal.
We are convinced that if we want to promote
B2B2X, we must garner abilities that enable us toVol. 15 No. 4 Apr. 2017

continue to be selected by our partners. If we are to
succeed in collaboration, we must have the ability tointegrate the strengths of all those involved in any
such collaboration, and NTT R&D must consistently
produce cutting-edge research results. We will notemphasize one or the other of the above but will commit ourselves to garnering the ability to collaborate
and pursuing basic and fundamental research.

14

Feature Articles: NTT Tsukuba Forum 2016 Workshop
LecturesResearch and Development Activities
toward Smart and Flexible Future
Network: NetroSphere Concept
Kimihide Matsumoto
Abstract

The NTT laboratories announced the NetroSphere concept in March
2015 with the aim of creating future networks that support the Hikari Collaboration Model (business model to wholesale fiber access). This article
introduces our recent efforts concerning NetroSphere and explains theimportance of creating future smart and flexible networks based on the
NetroSphere concept in order to accommodate the digitization of various
industries and the rapid growth of multiple Internet of Things services.
These Feature Articles are based on lectures given during workshops at
the Tsukuba Forum 2016 held on October 26, 2016.
Keywords: NetroSphere, future network, smart and flexible

1. Introduction
The progress made in information and communication technology (ICT) in recent years has led a multitude of industries that had not previously embraced
ICT to incorporate ICT into their businesses andreform their operations through digitization. At thesame time, the Internet of Things (IoT)—which connects various devices through wireless transmissions—has been rapidly expanding. Moreover,devices such as smartphones are improving in performance and functionality, and video services are
improving in image resolution, and as a result, theamount of communication traffic is steadily increasing.
A diverse range of industries utilizes communication networks, and consequently, there are diverse
requirements for different communication networks.
To handle these requirements and the continuing
increase in communication traffic, it is necessary to
not only create future networks economically but also
to make them flexible so they can handle additions
and changes to requirements.
1

From a historical standpoint, services provided bycommunication networks have long been centered on
telephony. However, the introduction of Internet connection services, video delivery services, and otherrecent changes has resulted in the triple play of Internet access, telephone, and video distribution becoming available in the era of next-generation networks(NGNs).
In addition, with the progress of digitization and the
IoT, it is necessary to understand that communication
networks no longer provide all services, but rather,
they support some of the diverse end-to-end services
provided by service providers in various industries. It
is thus considered difficult to sufficiently handle
these circumstances by utilizing demand-forecasting
techniques and network-design techniques that havebeen fostered on public switched telephone networks
and NGNs.
With these circumstances in mind, we consider that
future networks will have the features outlined below.
•	An architecture that can flexibly handle changes
resulting from fluctuations in demand and differing requirements
NTT Technical Review

Feature Articles

DesignPlanned procurement
and facility design

Incident-driven
maintenance

Relatively long life cycle(from quarter to year)

Operation

Rough modeling anddemand forecastingStatic traffic modeling anddemand forecasting

Dedicated
hardwareDesignSmart
network

Waterfall model
development

Flexible
network
Relatively short life cycle(from weeks
to months)

Sophistication andautomation by AI,
machine learning, etc.

Operation

Development

Dependence on
individual skills (difficultyof systemization)

Procurement when
demand arises

Agile development

Development
Softwarized functions

Stylized maintenanceand operation(a) Past network life cycle

Redundancy thanks
to virtualization(b) Future network life cycle

Fig. 1. Network life cycle.

•	Intelligent operation that can handle events thatare difficult to forecast•	A structure that efficiently achieves the abovestated features without incurring high costs
2. Life cycle of future networks
The life cycle of networks can be split into threephases: design, construction, and operation. That is, acommunication network is designed in accordancewith given requirements and demands, constructedon the basis of that design, and then operated. The
knowledge gained during operation is fed back to thedesign phase as required. However, with the progressof digitization and the expansion of IoT, it has
become necessary to change the way this life cycle isunderstood.
When services are directly provided by a communications carrier in the manner of conventional telephone networks and NGNs, the upstream of the life
cycle has tended to receive the most attention. In
other words, the approach taken has been to firmly
forecast demand in the design phase, optimize the
network design on the basis of the forecast demand,and procure hardware according to plan. In the development phase, requirements are specified, and the
network is developed in an orderly manner according
to the waterfall model. By doing so, operations are
optimized in the operation phase (Fig. 1(a)).
If the requirements concerning a communication
network are simple, and if fluctuations in demand arecomparatively easy to forecast, the above-described
approach is sufficient. However, the situation must be
Vol. 15 No. 4 Apr. 2017

reviewed if the communication network has numerous requirements or if the fluctuations in demand for
future networks are expected to vary considerably.
That is, since requirements and demand are indeterminable beforehand, the network design will proceed
in a rough manner, and hardware must be procured
according to each demand.
We aim to implement agile development in order toflexibly accommodate changes in requirements. To
handle events that are difficult to predict, new technologies such as artificial intelligence (AI) are being
applied in the operation phase to improve functionality and performance. To efficiently create such afuture network, we are simultaneously softwarizing
network functions by utilizing software instead of
hardware in the conventional manner, establishing
network flexibility and redundancy (reliability)
through virtualization of resources, and reducing
operational costs through automation and stylizationof maintenance (i.e., establishing a certain form for
network maintenance and making it routine)(Fig. 1(b)). In creating a future network, we consider
it important to establish a flexible network via the
upstream processes (design and construction) and asmart network via the downstream process (operation).
Our approach for the NetroSphere concept
announced in 2015 [1] involves efficiently creating aflexible network based on separation of resources andequipment, separation of functions and equipment,
and separation of optical and electrical components,
and a smart network for intelligent operation andmaintenance (Fig. 2).
2

Feature Articles

Flexible
network

Environment

Transport

TravelResource/Equipment
Separation

MedicalInnovation byservice collaboration

Logistics

ProviderCarrier

MVNO, ISP

Other companies

MemoryCPUIntelligent operationand maintenance- Obtaining forecasts of
network changes- Minimizing and avoiding
damage by quick adaptation
to changes/forecasts- Realizing one-stop andautomated operation

Service functions

Hardware/Software
Separation

Generic switch
Generic hardware

Optical/Electrical
Separation- Localizing electrical process by
expanding optical core network- Realizing super-economic andsustainable infrastructure

Manufacturing

Sports/Entertainment

Common API
Operation- Dynamically allocating resources
required by services- Streamlining equipment operationand improvement of reliability- Flexibly combining modularizedsoftware and hardware components- Swift and flexible accommodation tovarious needs

Smart
network

Storage

Optical transport
End user

API: application programming interface
CPU: central processing unit
ISP: Internet service provider
MVNO: mobile virtual network operator

Fig. 2. Key elements of NetroSphere concept.

3. Activities aimed at realizing theNetroSphere concept
At NTT laboratories, we are developing technology
in five areas in order to realize the NetroSphere concept (Fig. 3): (1) high-speed and highly reliable
server architecture technology for speeding up application development (MAGONIA), (2) transport network configuration technology for achieving both
scalability and economy (Multi-Service Fabric:
MSF), (3) network equipment modularization technology for enabling flexible and low-cost accessnetworks (Flexible Access System Architecture:
FASA), (4) enhancement of operational technology
by applying AI, and (5) verification of the NetroSphere concept (NetroSpherePIT). The current statusof these activities are explained below.
(1)	High-speed and highly reliable server architecture technology for speeding up application
development (MAGONIA)
This technology utilizes virtualization technology
to implement on a shared platform network functions
3

that in the past were implemented on exclusive-use
appliances with separate functional capabilities, andnetwork functions that were created with high-performance hardware. We confirmed that when this technology is applied to traffic simulation in ITS (intelligent transport systems), it enables congestion forecasting and signal control with high availability andscalability [2].
(2)	Transport network configuration technology forachieving both scalability and economy (MSF)
This is a technology for configuring clusters byflexibly and optimally combining and controlling
general-purpose switches. Since no exclusive-use
equipment is needed, installation and operation costs
can be reduced, and various services can be provided
in a prompt and flexible manner. We published thearchitecture of this technology in August 2016 [3],and we are continuing to collaborate with various
partners.
(3)	Network equipment modularization technology
for enabling flexible and low-cost access networks (FASA)NTT Technical Review

Feature Articles(4) Enhancement ofoperational technology byapplying AI

Network virtualizationand software control
OLT
(DBA)

BAS

CPE

PBX

Security EPC

DNS

DPI

Service provider(middle B in B2B2X model)

IMS

Orchestrator
controller(1) High-speed and highly
reliable server architecturetechnology for speeding up
application development(MAGONIA)

Simple and large capacity
optical transport core

APL APL
Generic
SW Generic Common PF
Generic
SW
SW
Generic
Generic GenericserverSW
SW
APL
Generic HW
Opt/radio IF
Opt. IFAPL
Generic HWOpt. IF
Opt/radio IF(2) Transport network
configuration technology forachieving both scalability
and economy (MSF)(3) Network equipment
modularization technology forenabling flexible and low-costaccess networks (FASA)(5) Verification of the NetroSphere concept (NetroSpherePIT)
APL: application
BAS: business application service
B2B2X: business-to-business-to-X
CPE: customer premises equipment
DBA: dynamic bandwidth allocation

DNS: domain name system
DPI: deep packet inspection
EPC: evolved packet core
HW: hardware
IF: interface

IMS: Internet protocol multimedia subsystem
OLT: optical line terminal
PBX: private branch exchange
PF: platform
SW: switch

Fig. 3. NTT research and development activities for the NetroSphere concept.

The modularization of access system functions andthe use of softwarization technology (access equipment modularization) in FASA enable it to shareequipment. They also simplify maintenance andoperations and achieve flexible and prompt handlingof services. In May 2016, we released a FASA white
paper, including FASA APIs (application programming interfaces) (proposal), and we are presently
seeking partners to participate in technical discussions concerning the development of technical specifications [4].
(4)	Enhancement of operational technology byapplying AI
We are working on enhancing operational technologies that utilize big data analysis, AI/machine learning, and other techniques to handle various kinds oflarge-capacity data (network equipment, server information, traffic information, etc.) acquired from communication networks and the cloud. We have recently
been working on anomaly detection technology andworkflow visualization technology using syslog(system-log analysis).
Vol. 15 No. 4 Apr. 2017(5)	Verification of the NetroSphere concept (NetroSpherePIT)
We have established a verification environment
called NetroSpherePIT as a venue for specifying andsharing common thoughts with various partners
regarding technology created based on the NetroSphere concept [5]. The name NetroSpherePIT isanalogous to a pit at a racing circuit, namely, a place
where experts from various fields (car bodies,engines, tires, etc.) come together and think as one asthey assemble racing cars and discharge them onto
the circuit. It is a venue for not only verifying technology but also promoting collaboration with ourpartners. Moreover, we think that by incorporating
networks utilized for daily work at our labs in NetroSpherePIT, we can operate NetroSpherePIT as avenue for accumulating our own operational technologies.
4. Future development
At NTT laboratories, we are striving to create a4

Feature Articles

smart and flexible future network that can handle theupcoming era of seismic change. By jointly creatinga wealth of value through collaboration with various
partners, we aim to promote research and development that is more open than ever.
References
[1]
[2]
[3]
[4]
[5]

5

Press release issued by NTT on February 19, 2015.
http://www.ntt.co.jp/news2015/1502e/150219a.html
Press release issued by NTT on April 12, 2016.
http://www.ntt.co.jp/news2016/1604e/160412a.html
Press release issued by NTT on September 28, 2016.
http://www.ntt.co.jp/news2016/1609e/160928b.html
Website of FASA,
http://www.ansl.ntt.co.jp/e/global/FASA/index.html
Press release issued by NTT on February 8, 2016.
http://www.ntt.co.jp/news2016/1602e/160208a.html

Author profile
Kimihide Matsumoto
Vice President, Executive Manager, Network
Architecture Innovation Project, NTT Network
Technology Laboratories.
He received a B.E. and M.E. from Nagoya
Institute of Technology, Aichi, in 1988 and 1990.
He joined NTT in 1990 and engaged in researchon traffic engineering and quality management intelecommunications networks. From 1999 to
2005, he developed systems for IP-based services
at NTT EAST. He is currently working on developing the architecture of future telecommunications networks.

NTT Technical Review

Feature Articles: NTT Tsukuba Forum 2016 Workshop
Lectures

Flexible Access System Architecture:
FASA
Akihiro Otaka
Abstract

The NTT laboratories announced FASA: Flexible Access System
Architecture, the new architecture based on the NetroSphere concept, inFebruary 2016. This article provides an overview of FASA, which isdesigned to achieve flexibility in future access systems, and introduces its
application to optical access systems accommodating mobile base stations.
Keywords: access systems, virtualization, FASA

1. Introduction
The NTT laboratories announced in February 2015
the NetroSphere concept, which is designed to enable
rapid creation and provision of various new services
through collaboration with business partners [1]. The
concept is based on the Hikari Collaboration Model(wholesaling of fiber access services) and aims todisaggregate network functions to small modules asmuch as possible and enable the network to flexibly
achieve required functions and capacity by combining various modules. The research and developmentof access networks will need to be synchronized with
the NetroSphere concept in order to achieve flexible
network configuration.
Current access networks have evolved under thesituation where individual systems have been developed for each provisioned service, so the configuration of network functions in the network equipment
depends on the service or the system vendor, and any
subsequent upgrading or addition of network functions is not flexible. In core networks, Ethernet communication is used in the generic server or router, so
it is not difficult to disaggregate the optical transmission function and the electrical frame processing
function. In access networks on the other hand, various frame formats such as EPON (Ethernet passive
optical network), GEM (generic encapsulation meth1od), and DSL (digital subscriber line) are used
depending on the transmission length, transmission
media, and geographical subscriber density. Thus, thegeneric network function area of access networks isdifferent from that of core networks.
The NTT laboratories announced FASA (Flexible
Access System Architecture) in February 2016 [2] asa specific NetroSphere concept for access networks.
FASA can also disaggregate access network functions to small modules and combine them flexibly, as
shown in Fig. 1. A feature of FASA is that it uses thesoftware module (FASA application) or the external
hardware module according to the network function.
For example, in the software module, it modularizes
and operates the bandwidth control function, network
maintenance function (OAM: operations, administration, and maintenance), and multicast process function. In the external hardware module, optical transceivers and network functions for error correction,
encryption, and framing, all of which require highspeed processing at wire speed, are modularized, andthe required modules are flexibly added according toeach transmission system. We can achieve the following objectives of the NetroSphere concept by combining each software module and external hardware
module for required functions.
(1) Quick provision of services
The addition of required network functions as
NTT Technical Review

Feature Articles

Today

FASA concept• Purpose-specified OLT• Difficult to add/change functions promptly

Service achieved by combining
modularized functions

OLT

New
function

Wavelength
control

OLT

Bandwidth
control

OAM

Multicast

Add/change newsoftware functions.

Generic hardware (Generic functions)
External hardware
moduleVendors’ proprietaryarchitecture andfunctional blocks
ONU

Purpose-specified
implementation

External hardware
module (EPON)

WDM/TDM-PON
ONU

ONU

ONU

ONU

ONU

Replace hardware module tomeet transmission
requirements.

OAM: operations, administration, and maintenance
OLT: optical line terminal
ONU: optical network unit
WDM/TDM-PON: wavelength division multiplexing/time division multiplexing - passive optical network

Fig. 1. FASA concept.

FASA applications into the system will enable quick
provision of services.
(2) Operating expenses (OPEX) reduction
Commonalization of maintenance and inventory
will reduce OPEX.
(3) Capital expenditure (CAPEX) reduction
The system configured using commonalized generic hardware will reduce CAPEX.
(4) Service continuity
Achieving the upgrading and replacement of generic hardware independent of network functions will
enable the continuous provision of services.
These activities require collaborative technology
development between telecom carriers, who set
requirements for network functions, and vendors,
who provide the technology to implement the systemand equipment. Therefore, the NTT laboratories
simultaneously called for collaboration with vendors
when it announced the FASA concept.
2. Key technologies of FASAFASA is based on three key technologies as follows. It is presumed that FASA will produce theVol. 15 No. 4 Apr. 2017

expected effect incrementally by realizing these technologies.
2.1 C
 ommon interface achieving function modularization and combination of function modules
We are now investigating the FASA common application programming interface (API) that defines thefunctions to be modularized and enables function
modules to be freely combined (Fig. 2). This API
requires technology to dynamically combine function
modules and to flexibly set and change the sequential
order of each function. Our ultimate goal is to enable
the operation of function modules on a generic server.
The immediate goal, however, is to design a configuration to implement the FASA common API withvendors’ dedicated equipment and to operate software function modules by using this API. One advantage of these software modules is that they can beused even if the dedicated equipment is replaced withgeneric servers in the future. Therefore, the developed software modules are available sustainably.
However, at this time, the softwarization of network
functions requiring high-speed processing at the wire
speed on the physical layer is difficult, so it is2

Feature Articles

Controller
FASA applications
MobileDBA

Wavelength
control

DBA

OAM

Multicast

Function
modularization

FASA common API
FASA platformCPU

NG-PON2

External hardware module

GE-PON

P2P

ASIC

ASIC

Mobile system

Residential users

ASIC: application-specific integrated circuit
CPU: central processing unit
DBA: dynamic bandwidth allocation

ASIC

Business users

GE-PON: Gigabit Ethernet PON
NG-PON2: Next-Generation Passive Optical Network 2
P2P: point-to-point

Fig. 2. FASA common API.

achieved using the hardware module, which can be
replaced externally. The NTT laboratories publisheda white paper explaining FASA and proposed someideas about the FASA common API.
2.2 Softwarization of function module
We are now investigating the implementation of thepassive optical network (PON) OLT (optical line terminal) in the server, as shown in Fig. 3. We achieved
the network function required in access networks as
an application on the operating system by using highspeed processing technology with software. We haveachieved the high-speed processing function in thephysical layer by using the external hardware module, and we are currently investigating whether thegeneric GPGPU (general-purpose graphics processing unit) can process the error correction function andthe encryption function in the physical layer by using
software in order to flexibly enhance the upgradablearea.
2.3 Function module cloud
We are targeting an effective system that centralizes
function modules that are not processed frequently
and that require low-speed processing, as shown in
Fig. 4. Some projects are currently underway such as
Cloud CO (Central Office) in the Broadband Forum(BBF) and R-CORD (Residential Central Office Re3

architected as a Datacenter) in the Open Networking
Lab (ON.LAB). These projects involve investigating
and standardizing the operation of access systems by
the controller on the software-defined network concept. The aims are to be able to flexibly control, set,
and maintain functions of access systems. In contrast,
the aim with FASA is to flexibly add and change thefunctions themselves, including the high-speed processing functions. Therefore, FASA complements theabove activities. The NTT laboratories proposed
starting the FASA project in the BBF, and standardization of FASA has begun.
3. Application of FASA: mobile access systems
in 5G era
FASA consists of technology for configuring
access systems, as mentioned in the previous section.
Therefore, the application of FASA—that is, how
NTT laboratories will realize flexible access systems
by using this technology—is explained in this section.
In fifth-generation (5G) mobile systems, manysmall cells are assumed to be located densely. PON is
the promising solution to accommodate densely
located base stations, as shown in Fig. 5. The application of PON to the 5G mobile access system utilizes
the existing fibers more efficiently than the current
NTT Technical Review

Feature Articles

Application layer
Virtual-OLT(Server)

MPCP

Realizing network
functions on OS by
high-speed software
processing

OAM,
Alarm

BRG

Software switch- Optimization of function
distribution of hardware
and software

OS/virtual middleware layer

External
hardwaremodule- High-speed processing
functions achieved using
external hardware
modules

Hardware layer
FEC, ciphering,encoding

PHY- Softwarization ofphysical layer with
GPGPU

ONU

BRG: bridge block
FEC: forward error correction
GPGPU: general-purpose graphics processing unit

MPCP: multipoint control protocol
OS: operating system
PHY: physical layer

V-OLT
HW

HW abstraction
layer (HAL)

Controllers andnorthboundapplications

Fig. 3. Modularization of software function virtual-OLT.

Application
Application

Functional
blocksFunctional
blocksFASA applications

Functional
blocksConfiguration
controller

OpenFlow
controller

NETCONF/YANG
OpenFlow
OpenFlow agent

NETCONF agent

OLT to Ethernet
Abstraction & interwork function
OMCI stack

Functional
blocks

FASA
common API

NETCONF client

OMCI over X
OMCIencap/decap

NETCONF/YANG
NETCONF
agent

OLT data plane

FASA platform

External hardware
moduleSource: bbf.2016.769.00
Cloud CO: Cloud Central OfficeEncap/decap: encapsulation and decapsulation
HW: hardware
NETCONF: Network Configuration Protocol defined by
IETF (Internet Engineering Task Force)

OMCI: ONU management and control interface
R-CORD: Residential Central Office Re-architected as a Datacenter
YANG: A data modeling language for NETCONF. YANG
is an acronym for Yet Another Next Generation.

Fig. 4. FASA and Cloud CO and R-CORD projects.

point-to-point system and drastically reduces thenumber of interfaces in the equipment in the central
Vol. 15 No. 4 Apr. 2017

office. Consequently, it helps to reduce the site space
and the power consumption.
4

Feature Articles

CPRI based MFH

PON based MFH

RRHs

BBU

RRHs
BBU
OLT

Requires more than
160 Gbit/s/link

Increased fiberand port count

Reduction to less than
30 Gbit/s due to packet
based transmission

Drastic reductionof fiber and port
count

CPRI: Common Public Radio Interface
BBU: baseband unit
RRH: remote radio headFig. 5. PON based mobile fronthaul (MFH).

The NTT laboratories are investigating the following approaches in order to apply PON to mobile
fronthaul (MFH):(1)	Redefinition of the functional splitting point
between base band unit (BBU) and remote radio
head (RRH) to reduce the bandwidth of MFH
with packet based interface(2)	Cooperation between the mobile and opticalschedulers to achieve low latency in upstream
communication
These approaches enable packet multiplexing foreffective traffic aggregation in MFH and a change ofthe connecting condition between the BBU and the
RRH in their future virtualization. However, these are
ongoing investigations, so network functions have tobe revised quickly and implemented in the system inline with technological trends and the standardization
progress. Therefore, it is preferable to realize theserevisions through FASA configurations that smoothly
change and modularize network functions.
3.1 Redefinition of functional splitting point
The current Common Public Radio Interface(CPRI) based MFH configuration requires 16 times
the optical transmission capacity of the radio frequency (RF) capacity because the base station isdivided into RF processing and baseband processing.
For example, a 5G system requires 160-Gbit/s transmission in the optical access link for the 10-Gbit/s RF
capacity in this configuration, which makes it too
expensive. Optimal redefinition of the functional
splitting point between BBU and RRH will make it
5possible to reduce the optical transmission capacity
to less than one-fifth that of the current configuration
without degrading the CoMP (coordinated multipointtransmission) performance of several RRHs. Moreover, the current CPRI always transmits optical signals at a fixed bitrate regardless of the user traffic. In
contrast, this technology transmits packets only when
the user traffic is transmitted, so it enables packet
multiplexing. The standardization of this interface in
MFH is being discussed in the 3rd Generation Partnership Project (3GPP).
3.2 C
 ooperative technology between mobile systems and PON
The principle of the cooperative technology
between a mobile system and PON is shown in Fig. 6.
PON shares the bandwidth with several optical network units (ONUs) and uses dynamic bandwidth
allocation (DBA) for the upstream signal control.
DBA can improve the bandwidth utilization efficiency, but the bandwidth allocation calculation causes
high latency. Although this latency is not a major
issue in normal Internet access, it becomes a major
issue in the 5G mobile access system, which requires
low latency. We are working to solve this issue by
investigating technology to reduce the latency byachieving cooperation between the schedulers of themobile system and PON. The mobile system controls
each sending time of the upstream signal to eachpiece of user equipment by scheduling them without
RF interference. The PON can schedule the sendingtime of each ONU in advance by transferring the
NTT Technical Review

Feature Articles

UE

RRH

OLT
Timing control of
ONU’s transmission

ONU

Bandw

idth request

Timing control ofUE’s transmission

Calculation
on scheduling upon data
arrival at ONU
Timing coordinationin advance bycooperativeinterfacenocatioidth all

Bandw

BBU

Scheduling latency
Transfer w/oschedulinglatency
UE: user equipment

Fig. 6. Cooperative technology between mobile system and PON.

above information and can transmit upstream signals
without the high latency caused by the DBA.
We are proposing the standardization of this technology to ITU-T (International Telecommunication
Union, Telecommunication Standardization Sector)
and are also going to propose it to 3GPP, the organization responsible for mobile system standardization.
In the next-generation MFH, the optical transmission
capacity depends on the total traffic from all user
equipment, so the optical access system accommodating mobile traffic requires flexible bandwidth
allocation. Therefore, we are investigating a way toachieve large-capacity transmission of 40 Gbit/s by
NG-PON2 (Next-Generation Passive Optical Network 2), which combines time division multiplexing
and wavelength division multiplexing, as well as away to achieve optimal time slot and wavelength allocation to the RRH based on the user traffic.

Vol. 15 No. 4 Apr. 2017

4. Next step
The NTT laboratories will continue working to
improve the technologies of FASA and to expand its
use by many operators and vendors. Efforts will also
continue on standardizing FASA in order to realize a
flexible, cost effective, and sustainable access system.
References
[1]

[2]

K. Ono, H. Yoshioka, M. Kaneko, S. Kondoh, M. Miyasaka, Y.
Soejima, T. Moriya, K. Kanishima, A. Masuda, J. Koga, T. Tsuchiya,
N. Yamashita, K. Tsuchikawa, and T. Yamada, “Implementing theNetroSphere Concept at NTT,” NTT Technical Review, Vol. 13, No.
10, 2015.
https://www.ntt-review.jp/archive/ntttechnical.php?contents=
ntr201510fa2_s.html
Website of FASA, http://www.ansl.ntt.co.jp/e/global/FASA/index.
html

6

Feature Articles

Author profile
Akihiro Otaka
Executive Manager, NTT Access Network Service Systems Laboratories.
He received a B.S. and M.S. in physics from the
University of Tokyo in 1989 and 1991. He joined
NTT in 1991 and developed optical lithography
technologies for LSI (large-scale integrated circuit) fabrication. In 1998, he began working on
the development and standardization of opticalaccess systems such as Gigabit and 10 Gigabit
EPON. From 2010 to 2014, he was with NTT
EAST R&D Center, where he worked on opticalaccess, wireless access, and wireless home networks. He has been with NTT Access Network
Service Systems Laboratories since 2014. He is amember of the Institute of Electronics, Information and Communication Engineers and the Japan
Society of Applied Physics.

7

NTT Technical Review

Feature Articles: NTT Tsukuba Forum 2016 Workshop
LecturesResearch and Development of
Innovative Operation Technology for
Access Network Infrastructure
Kiyoharu Sasaki
Abstract

The Optical Access Network Project underway at NTT Access Network
Service Systems Laboratories involves research and development onaccess network technology. This article is based on a lecture given at the
NTT Tsukuba Forum held in October 2016; it introduces the research anddevelopment designed to innovate access network operation and the areasof development planned for the future.
Keywords: innovation of operation, equipment/facility inspection, Tsukuba Forum

1. Introduction
The NTT Group has built and operates huge numbers of telecommunications facilities in Japan, andthis is continuing with the spread of telephone networks and optical broadband services nationwide. In
order to continuously provide safe and secure social
infrastructure services, a lot of effort and resources
are required for operation and maintenance, and thus,
the cost of maintaining and operating these facilities
is extremely high. NTT Access Network Service Systems Laboratories (hereinafter referred to as AS
Labs) has undertaken initiatives to reform the operation of these huge numbers of telecommunications
facilities. We aim to streamline the process of inspecting equipment and facilities through innovation.
AS Labs has been studying the equipment inspection techniques in cooperation with NTT EAST and
NTT WEST in order to improve efficiency. Inspection work in the future, however, will require technical innovation. This will involve checking and evaluating equipment structures quantitatively and in aplanar manner with centimeter-order precision by
maximizing the use of robotic technology such as
mobile mapping systems (MMS). An MMS is a tool
for acquiring point cloud data and images that is1

installed on measuring vehicles equipped with a highdensity laser, camera, and GPS (Global Positioning
System). This technology is already being used in thecivil engineering construction industry and in the
mapping industry. The reflection of a laser beamemitted at 1 million points per second from a highdensity laser onto the measuring equipment in themeasuring vehicle produces white trace data called
point cloud. Each point in a point cloud has coordinates, so accurate position information can beacquired, thus enabling spatial data of equipment tobe acquired together with image data obtained by thecamera (Fig. 1).
In addition, AS Labs has been developing technology to model the point cloud data measured by MMS
and automatically detect the condition of a piece ofequipment. For example, in the case of a utility pole,modeling is achieved by extracting aggregates ofcircles from point cloud data and then removing noise(Fig. 2). Once the modeling is done, it is possible todetect the presence/absence of abnormalities such as
inclinations and deflections, and to determine what
the extent of the abnormality is. For example, in thefield photograph on the far left in Fig. 2, the telephonepole appears to be leaning. When modeling is doneusing the above-mentioned technique, we see that it
NTT Technical Review

Feature Articles

Omnidirectional
cameraHigh-density laser(1 million points
per second)

Point cloud

Image

Fig. 1. MMS measuring vehicle and acquired data.

Field photo

MMS
Point cloud + pole model

MMS
Pole modelHeaddisplacement:
62 cm(Slope: 39 cm,
Deflection: 23 cm)

10.98 m

Displacement:
27.5cm(Slope: 18 cm,
Deflection: 9.5 cm)

5m

Slope: 3.3°

Fig. 2. Automatic detection of poles and three-dimensional modeling.

has shifted to the right from the center position by 62
cm at the head of the utility pole and 27.5 cm at theaerial position of the cable. Furthermore, we candetermine that the deviation of 62 cm at the head ofVol. 15 No. 4 Apr. 2017

the utility pole is caused by a 39-cm inclination of theutility pole and a 23-cm deflection of the utility poleitself. As with the case of the utility pole, the MMS
can measure the distance to the ground from the cable2Feature Articles

Robotic technology (MMS, drones),
high-precision map
Point cloud data

Large capacity DB

Environmental dataetc.

IoT (sensor technology)
AR (augmented reality)

Obsolete equipment
data

Image analysis
Machine learning(deep learning)
AI

Innovation of
inspection work

Structure design for safe
and secure facilities, basedon actual conditions

DB: database

Fig. 3. Technology category related to inspection innovation.

attached to the utility pole. Therefore, the shortage ofthe distance to the ground from the cable, which isone of the problems in facility operation, will be possible to grasp, and concrete measures to rectify it canbe implemented.
We experimentally measured and analyzed facilities using an MMS in the Koiwa area of Tokyo in
March 2016. The Koiwa area has about 10,000 telephone poles. In MMS measurement, safety is an
important factor, so the range of safe traveling (interms of speed and time) of the measuring vehicle istaken into consideration. Thus, we were able to safely
measure 2000 poles per day. The measurement
results indicated that most utility poles were found tohave a deflection of 5 cm or less. A deflection of 20
cm will likely lead to cracking, and cracks will enable
water to penetrate the pole, resulting in possible deterioration of the rebar. None of the utility poles in thismeasurement area had deflections as large as 20 cm,
so they were in relatively good shape.
To utilize data acquired by MMS, we first need todevelop a high-precision map. The map currently
being used has a scale of 1:2500, with a reported errorof about 2 m. Utilizing the data acquired with MMS
makes it possible to generate a highly accurate mapwith a scale of 1:500. A map at this scale has an errorof about 30 cm, so the equipment position can be
grasped very accurately. Moreover, in addition tofacility inspection, we believe that with such a map
we can improve services such as selecting equipment
3

with greater precision when providing NTT services.
This article thus far has focused on robotic technology using MMS, which is a method of inspecting
objects from the ground. However, we are also considering using drones to obtain an aerial viewpoint,
and we are planning to utilize the high-precision map
based on the coordinate positions obtained by drones.
2. Inspection innovation for a safer society
Five technological fields are considered to be key
areas in designing safe and secure telecommunications facilities that reflect the innovation and theactual conditions of inspection work. These fields are
the Internet of Things (IoT), augmented reality (AR),image analysis, machine learning, and artificial intelligence (AI). These are very trendy terms; however,since a wide range of operational services are provided in business, we would like to realize a society
in which telecommunications facilities are continuously monitored (watched over) by promoting innovation through the use of the technologies in thesefields (Fig. 3).
2.1 IoT and fiber sensing
After the MMS is used to grasp the equipment condition, it will be necessary to immediately repair or
replace any equipment determined to be in poor condition. Equipment with progressing deterioration but
not at a stage requiring immediate renewal will be
NTT Technical Review

Feature Articles

Cloud

It’s bending.

Base station

Sensors
Master unit
It’s bending.

Sensors

It’s bending.

(a) IoT

It’s bending.

(b) Fiber sensing

Fig. 4. IoT and fiber sensing technology.

recorded as needing a follow-up observation. It iscurrently only possible to increase the frequency of
manual inspections by workers. However, installing asensor (IoT technology) on equipment that needs
such follow-up observations will enable the equipment state to be sent automatically any time someone
approaches the equipment. In addition, fiber sensing
is expected to be used for equipment in poor condition, with notification of the equipment condition
being automatically sent to the appropriate department. Such remote monitoring will make it possible
to detect dangerous conditions and their signs at an
early stage (Fig. 4).
2.2 AR
The year 2016 saw everyone talking about Pokémon GO, a virtual monster-like character that appears
on a map with AR technology. We can represent theequipment information obtained using robotic technology and IoT on a map by applying AR technology
with a smartphone application. In this way, we aim toprovide a fun way for experts and other members ofsociety to be able to watch over society and to createa system that can accumulate useful data. In terms ofwatching over society, we can imagine using the system to keep an eye on elderly people who may have atendency to wander, but we would like to use the system to monitor NTT facilities (i.e., equipment andbuildings), which are also aging in our aging society.
2.3 Image analysis
The image analysis feature involves using the photos taken by MMS of corroded branching hardware,rusting equipment, lateral cracks of utility poles, andVol. 15 No. 4 Apr. 2017

other such defects in order to assess the degree ofdamage and to plan for repairs. As camera technology
advances, we will need to adapt how we proceed withmaintenance work. The current use of this technology
to detect wear in manholes is steadily progressing at
AS Labs.
2.4 Machine learning
It is also important to be able to apply machinelearning (deep learning) of images. For example,
NTT Media Intelligence Laboratories is advancing
machine learning of images, and even if an object isplaced at an angle that is different from the registeredimage, it can be identified and detected. We aim toutilize this technology to determine the appropriate
time to replace equipment such as closures, branching hardware, and lead-in lines installed in outdoor
facilities (Fig. 5).
We will continue to innovate inspection work by
combining the technologies introduced so far. The
next task is to examine what the entire structure is like(Fig. 6). When measuring structures using MMS, we
can see the routes of communication cable lines andsuspension wires. It is also possible to determine
whether or not a branch line or support pillar is necessary depending on the wire route situation. In thisway, monitoring the entire facility situation such as
the arrangement and state of the utility pole, the communication cable lines, the wire route, the branchline, and the support pillar as one system, and by seeing the balance of the whole system, it will likely bepossible to analyze and predict any imbalance or distortion of such facilities. There is no problem when
the balance of the entire system is sound. However,4Feature Articles

Corroded communication
Close up of corroded part
branching hardware
Horizontal crack:
Horizontal crack:
0.2 mm
0.1 mmHorizontal crack:
0.1 mmLongitudinal crack:
0.3 mmHorizontal crack:
0.2 mmObtaining images using MMS
Cracked telephone pole

Automatic recognition of cracks
by image analysis

Fig. 5. Image analysis technology.

MMS
Point cloud + pole model

Field photo
Other company’s branch lines

TensionNo NTT branch line

Tens

ion

lect

Def

Combined
loads

ion

Load

163°

Height: 9.76 m
Slope: 1.3°
Deflection: 2.7 cm(5 m from ground)Fig. 6. Evaluation image of structure.

most of the existing facilities are 30 to 40 years old,so some of them are structurally unbalanced. Consequently, it is preferable to confirm the safety andsecurity of such facilities according to the structuraldesign reflecting the actual situation.
2.5 AI
Until now, we have investigated the new approachbased on information on the structure and material ofequipment, but further innovation of inspection work
will not reach a sufficient level unless external infor5

mation (external factors) is also taken into consideration. External factors include environmental indicators such as information on other companies’ equipment, temperature, humidity, and other environmental data. It is important to combine these indicators todetermine when to replace NTT equipment so as to
avoid unnecessary capital investment by using equipment for as long as possible. AI technology can comprehensively support experts in deciding how to utilize the acquired data when updating or maintaining
equipment. Therefore, we intend to further develop
NTT Technical Review

Feature Articles

Material deterioration
diagnosis• Corrosion ofsuspended wire
• Corrosion of
branching hardware

Development

AI

Structure deterioration
diagnosis• Pole, cable• Drop cable

Image analysis /machine learning(3) Operation
innovation

3D point cloud, AR,
IoT, fiber sensing
MMS, robot(2) Technology todrive innovation
High-precision map(1) Commercial
technology

Now

FutureFig. 7. Three pillars of inspection innovation.

AI technology in collaboration with partners both
inside and outside the NTT Group.
We can summarize the above inspection work as
being the three pillars of inspection innovation(Fig. 7).The base involves using general-purpose
technologies such as MMS, robots, and high-precision maps ((1) in Fig. 7). The end goal is to improve
the accuracy of technology applied for diagnosing thedeterioration of structures and materials and to
improve the efficiency of operations ((3) in Fig. 7).
The element connecting these is to combine the 3D(three-dimensional) point cloud we are now researching and developing and the technology described here((2) in Fig. 7). Our goal is to continue to expand thesethree pillars of inspection innovation from now on.
We have manufacturing know-how that we haveacquired at AS Labs for this effort, but our future
efforts will not be realized unless we create new
operation methods and techniques by collaboratingwith others in this field. The capability of field personnel is NTT’s valuable asset. My aim is to improvethe efficiency of NTT’s business operations by successfully combining the element that improves efficiency through technology development with theelement that increases the professional ability of field
personnel.

Vol. 15 No. 4 Apr. 2017

3. Future deployment of services
In the environment surrounding ICT (informationand communication technology), the demand for
optical communication, which was always the centerof equipment construction, is showing a tendency ofsaturation. As we pursue the Hikari Collaboration
Model (wholesale fiber access service), various uses
such as IoT, cloud formation, and the fusion of wired
and wireless services are progressing, and the deployment of new services is expected. The NTT Group
must operate facilities and services with the optimal
number of personnel, while maintaining the qualityof the equipment in order to take advantage of new
business opportunities.
To achieve innovation of equipment/facility inspection, it is necessary to change not only the operation
technology but also the current network to someextent. The optical network that NTT has built andexpanded in Japan is another valuable asset of the
NTT Group and ultimately of Japan, and it is therefore necessary to improve it so that it is more efficientand economical.
There are two necessary elements for updating
access networks. One is our new access system architecture called FASA (Flexible Access System Architecture), which enables us to modularize and combine
the functions of the access network equipment so that
we can provide various services flexibly and promptly.
6Feature Articles

Another is the need for a new ground design for the
optical fiber network. One example is to simplify theaccess network (e.g., aggregation of function points).
We are currently placing splitters in optical networks
and placing optical line terminals in public switched
telephone networks in small buildings and considering how we can aggregate some of them. We would
like to expand the scope of remote maintenance andincrease the efficiency of operations by reducing theamount of maintenance done on site. This is referred
to as equipment renovation at AS Labs. We plan toresearch the innovation of operation and equipment
renovation and the way the network should improvein the future.
In our vision of the future access network infrastructure that expands optical network services toevery person, thing, and business and continues tosupport society as a safe infrastructure beyond theage anywhere, any business, any period, we aim to7

deepen our cooperation with those we are collaborating with and strive to realize the results of researchand development in a timely manner.

Author profile
Kiyoharu Sasaki
Senior Manager, Optical Access Network Project, NTT Access Network Service Systems Laboratories.
He joined NTT in 1989. During 2002–2005, he
was with NTT Access Network Service Systems
Laboratories as a Senior Research Engineer,where he worked on the development of the optical access system. During 2007–2014, he was aGeneral Manager at NTT EAST, where he helped
develop the operation system for the opticalaccess network.

NTT Technical Review

Feature Articles: NTT Tsukuba Forum 2016 Workshop
LecturesWireless Access Technologies to
Enable a Variety of Services
Masato Mizoguchi
Abstract

In the wireless access project at NTT Access Network Service Systems
Laboratories, we are researching and developing wireless access technologies centered around wireless local area network (LAN) technology.
This article describes the issues that have arisen due to the growing use ofwireless LANs and introduces our research and development efforts
aimed at solving these issues and expanding the use cases of wirelessLANs.
Keywords: cooperative wireless LAN, unlicensed radio, fifth-generation mobile

1. Introduction
Wireless local area networks (LANs), or Wi-Fi*1
networks, are gaining much attention due to the rapid
growth in the number of user devices including
smartphones and tablets being used in homes andoffices. It was reported that in 2016, over 50 million
user devices equipped with wireless LAN functions
were sold in Japan [1]. Access points (APs) are also
being installed to handle the increasing traffic inmobile networks, and the number of users of public
wireless LAN services is increasing.
One of the factors behind the spread of wirelessLANs is that they operate on the unlicensed frequency band, which has made it possible for users to
install their own equipment for as little as $100 or so.
To provide this feature, the wireless LAN standard
IEEE*2 802.11 was established in 1997 as the first to
use wireless access control methods with autonomous distributed control, which is called carrier sense
multiple access with collision avoidance (CSMA/
CA). The maximum transmission speed of this initialstandard was 2 Mbit/s, but that has risen 1000-fold injust under 20 years, where the products compliant
with the latest IEEE 802.11ac standard have a maximum speed of 1.7 Gbit/s (Fig. 1). Throughout thistime, CSMA/CA has remained the basic wireless1

access control method, allowing for backward compatibility with earlier wireless LAN equipment.
CSMA/CA is a mechanism that allows multiple
wireless devices to share the same frequency channel[2]. Instead of having a centralized controller to control the access of each device as in the mobile phonesystem, in CSMA/CA the wireless APs and user
devices perform autonomous distributed channel
access before their radio emissions so as not to interfere with those of other devices. Specifically, thismethod carries out transmission after ensuring there
are no radio waves from other terminals (carrier
sense) and pausing for a prescribed random interval.
It thus avoids interference with the radio transmissions of other terminals (collision avoidance),enabling multiple devices to share the same frequency channel (multiple access). Centralized access
control methods are effective in systems where eachlicensed operator occupies and uses a different set of
frequencies, but with unlicensed wireless access,autonomous distributed control is necessary in orderfor radio waves to be shared by the devices of different owners.

*1 Wi-Fi is a registered trademark of Wi-Fi Alliance.
*2 IEEE: The Institute of Electrical and Electronics Engineers

NTT Technical Review

APDownlink
efficiency

SU-MIMO
technology

Throughput (bit/s)

1G

AN .11n

.11ad
.11ac

Interference

Throughput
reduced due tointerference

AP interference control

.11ax

10G

AP

AP

LTE-A

L
ess

100M

.11a

10M

100K

AP

Downlink MU-MIMO
technology

100G

1M

AP

Highercapacity

Many-to-many
communication

OFDM
technologyAP

One-to-many
communication

Higherdata
rate

One-to-one
communicationAP

One-to-one
communication

Feature Articles

rel
Wi
.11g

.11b
802.11WCDMA

LTE
le ionib
Mo nicat
HSDPA
mu
m
co

High-efficiency wireless LAN technology

GSM
PDC
1995

2000

2005

2010

2015

(Year)

GSM: global system for mobile communications
HSDPA: high-speed downlink packet access
LTE: Long Term Evolution
LTE-A: LTE-Advanced
MU-MIMO: multi-user multiple input multiple output
OFDM: orthogonal frequency division multiplexing
PDC: personal digital cellular
SU-MIMO: single-user MIMOWCDMA: wideband code division multiple accessFig. 1. Evolution of wireless LAN standard technology.

2. Issues of wireless LAN technology
Despite the popularity and convenience of wirelessLANs, there has been an increase in the problems
caused by excessive numbers of users. In an environment where many wireless LANs are used in close
proximity to one another, it is harder to secure transmission opportunities in the CSMA/CA protocol,
resulting in a higher incidence of packet errors due tocollisions. Problems are also caused by congestion of
wireless channels caused by the exchange of management signals such as beacon signals that are periodically transmitted by wireless APs, and probe signalsthat are used by terminals searching for a wireless AP
to connect to. This can make it impossible to makeproper use of wireless LANs in busy places such as
train stations where many people would like to use
them.
Vol. 15 No. 4 Apr. 2017

As Japan prepares for the major events in 2020,
there are growing expectations for the provision ofentertainment services using wireless LANs in stadiums. However, with the current wireless LAN technology, a stadium is an even more difficult environment than a train station. When providing high-bandwidth content such as videos to large numbers ofspectators in a stadium, it is possible to increase thetraffic capacity to some extent by installing wirelessAPs more densely, but the traffic capacity does not
rise in proportion to the number of installed APs. In a
stadium, the line of sight between the spectator seatsis particularly good, and it is usually possible forradio waves from a wireless LAN installed in theback stands to be received in the main stands. In thissort of environment, many wireless APs have to contend for the same frequency channel, resulting inlower traffic capacity per wireless AP.
2

Feature Articles

Development of the fifth-generation mobile communications system (5G) is underway worldwide aspart of efforts to exploit the expected commercial
opportunities that will arise in 2020. Mobile traffic iscontinuing to grow due to the increasing use of smartphones and advances in mobile applications. Although
the rate of increase has eased lately, it is still growing
by a factor of 1.4 every year according to a recent
report [3], and it is expected that the amount of traffic
in 2020 could be about a thousand times greater thanin 2010. To accommodate this traffic, 5G technologies that use a combination of diverse wireless accesstechniques, including the use of new frequency
bands, are being researched and developed, and it isexpected that wireless LANs and other unlicensed
wireless technologies will also be used as a way of
supporting 5G traffic [4].
At the Radio Policy Vision Council that met in
December 2014, the Ministry of Internal Affairs andCommunications resolved to secure a frequency
bandwidth in the 2700-MHz range for mobile communication systems by 2020, with the assumptionthat mobile frequencies will be integrated with thefrequencies used for wireless LANs [5]. However, as
mentioned above, wireless LANs using unlicensed
frequencies suffer from poor throughput in congested
radio environments. Consequently, improving thecharacteristics in congested environments is a major
challenge in order to accommodate mobile traffic in
unlicensed bands.
3. Development of wireless LAN technology
at NTT
In order to implement 5G services in time for the
big events of 2020, further evolution of wireless LAN
is expected. To respond to these needs, we mustensure that service quality is maintained even in environments where wireless APs and terminals arepacked closely together. One way of minimizing thedeterioration of wireless LAN quality in high density
environments without damaging the ease of access toordinary users to wireless LAN services is to continue using the CSMA/CA distributed access control
method while optimizing wireless resources such as
the transmission power and the number and bandwidth of wireless channels.
The current wireless APs generally choose wirelesschannels in which there are few interfering APs after
observing wireless AP signals in the vicinity, but inenvironments with high wireless LAN density, APsthat are liable to cause interference are themselves
3

subject to interference from other APs. As a result, thewireless environment can become extremely congested. In such circumstances, a complete overhaul of
the radio environment is warranted. At NTT laboratories, we are researching and developing an architecture called cooperative wireless LAN, whereby information about the wireless environment is collectedfrom multiple APs, and the parameters of each wireless AP are set appropriately based on this information. Wireless access control is still performed by
CSMA/CA autonomous distributed control, whilesome of the wireless AP parameters are optimized bycentralized control in order to improve the overall
bandwidth usage efficiency.
In May 2014, the IEEE 802.11 Working Groupembarked on the standardization of high-efficiency
wireless LAN (11ax) as the next generation standard.
The technical requirements set by this standard
include the provision of an operating mode where theaverage throughput is at least four times that of aconventional terminal in high-density environments,
and work is under way with the aim of implementing
this standard by the end of 2018. Although compatibility with high-density environments is thus being
promoted for standard technology, the range ofparameters that can be set according to diverse needsin the 11ax standard is becoming broader, and webelieve that wireless AP control would work more
effectively in a cooperative wireless LAN. NTT is
actively participating in the 11ax standardization process by promoting the implementation of standards
that are suitable for cooperative wireless LAN configurations, and leading in the development of 11axcompatible radio resource control techniques.
4. Efforts aimed at implementing a cooperative
wireless LAN platform
It is thought that a cooperative wireless LAN architecture, where some of the wireless AP parameters
are controlled centrally from the cloud, could be
developed to provide diverse services in addition to
wireless resource control functions (Fig. 2). This section introduces a number of techniques that we areworking on with the aim of providing a platform withdiverse functions obtained by controlling wirelessAPs.
 ooperative wireless LAN channel setup
4.1 C
technique
The configurable wireless resources of an ordinary
wireless AP include the wireless channel and channel
NTT Technical Review

Feature Articles

Other operators/service providers
Implemented as a platform

5G cooperation
Extension to cellular

Wireless LAN service functions

Maintenance/
operation

Wireless resource
control

Location estimation
Coupon delivery

Fast authentication

Network control engine group

LTE-A,
5G

Wireless LAN
controller

Home gateway• Municipal Wi-Fi• Stadium Wi-Fi

Cellular

Public area

OfficeHome

Fig. 2. Platform for deployment of diverse wireless services.

bandwidth. In 2015, we developed prototype channel
configuration software that optimally configuresthese wireless resources based on wireless environment information collected from multiple wirelessAPs. This technology uses the collected wirelessenvironment information to construct a virtual wireless LAN environment on a server, and repeatedly
tries out different resource settings in this virtualenvironment in order to converge settings that maximize the predicted throughput performance [6]. We
used this technique to perform optimal wireless channel configuration in a free Wi-Fi service at the Tsukuba Forum 2016 event. We also constructed a premium area where specific wireless APs were configured for high-speed communication, enabling us tovalidate this technique (Fig. 3).
4.2 C
 ooperative wireless LAN with distributed
smart antennas
In environments such as stadiums where wirelessLANs are subject to very high-density use, it is not
sufficient to simply optimize the wireless channel
configuration. Instead, technology is needed to suppress interference more fundamentally. We are therefore developing a cooperative wireless LAN system
Vol. 15 No. 4 Apr. 2017with distributed smart antennas arranged so that multiple wireless AP antennas are placed close to the user
terminals. Since this technique allows communication to take place without scattering radio waves
around any more than necessary, it allows frequency
channels to be recycled over shorter distances, thereby maximizing the area throughput [7] (Fig. 4).
Although distributed smart antenna technology has
already started to be introduced into mobile systems,
its application to CSMA/CA systems has up until
now been considered difficult. The application of
distributed smart antennas should make it possible toachieve at least double the overall throughput of aconventional system.
4.3 W
 ireless LAN service function: radio wave
environment visualization
By making use of the wireless environment information collected by terminals as well as wirelessAPs, it is possible to perform wireless control that isbetter suited to the user’s environment. In the future,by analyzing the collective intelligence obtained as
wireless environment information from devices thatare in regular use, it should be possible to ascertain
the status of wireless environments at many different
4Feature Articles

Venue 6

Venue 1MAS

Reception Shuttle bus stop

Main Lounge
Fast and reliable Wi-Fi access!

Venue 4

MuseumPremium area
A trial of cooperative
wireless LAN channel
setup technique forhigh-density
environments isunderway.

Shuttle bus stop
Evacuation space

Restaurant

Venue 5

Venue 3 (outdoor)

Venue 3 (indoor)

Taxi station

Gakuen-higashi Odori Ave.

Evacuation space

Access point

Venue 7 (1F)(2F)
To Tsukuba Sta.

Venue 2

To Mt. Tsukuba

Restroom
Smoking room
AED

Real-time display showing that the premiumarea achieved higher throughput than the other areas

Fig. 3. Conducting trials at the Tsukuba Forum venue.

APs using the same frequency channel
Interference area
AP

AP
Communication area

The large interference area limits the repeated use of frequency channels.
(a) Ordinary AP

Distributed antennas

Received power
High

AP

AP

AP
Low

The interference area can be reduced, enabling APs to bearranged with higher density.
(b) APs with distributed smart antennas

Fig. 4. Application of cooperative wireless LAN technology to distributed smart antennas.

locations in real time, and to promote the efficient useof radio waves. At the NTT R&D Forum held in February 2016, we tested a service based on a reduced setof features from the technology discussed here that5

created and provided free Wi-Fi signal strength maps
using a terminal application provided to visitors. As aresult, we confirmed that it was possible to visualize
the wireless environment in almost real time [8]NTT Technical Review

Feature Articles

BLE beaconsfor obtaining
location information

Everyone’s locations arecollected and analyzed on
the cloud.

Classifying trends of radio wave
usage and making utilization patterns

Network
Optimizing wirelessconfiguration policy
according to the patterns

Updated in real time
Wi-Fi radio map

Acquired user-location
data are linked touser-side information.

User terminals

Wi-Fi
APs

Reception
Cloaks• Wi-Fi signal strength, control-packet information, and traffic• Information from sensors implemented in smartphones

Restaurant

BLE: Bluetooth Low Energy. Bluetooth is a registered trademark of Bluetooth SIG Inc.

Fig. 5. Wireless LAN service function: radio wave environment visualization.

(Fig. 5).
4.4 Cooperation between 5G and wireless LANs
In 5G, it is expected that devices will not only beable to switch between wireless LAN connections
and mobile circuits as they have been able to do sofar, but will also be able to use unlicensed wirelessservices in close cooperation with mobile networks
as a heterogeneous network [5]. The key technologies
needed to achieve this are thought to include technologies for ascertaining the quality of unlicensed
wireless circuits and controlling wireless resources toreduce interference. Even in unlicensed wireless services where the quality tends to become unstable
during high-density use, it will still be possible toselect and use services of favorable quality if the service quality can be estimated with high precision [9].
Also, when using wireless resource control toimprove the quality of unlicensed wireless services,mobile circuits can be used as control circuits for
unlicensed wireless services to perform control using
wireless environment information collected from theterminals. This should make it possible to improve
the service quality even further [10] (Fig. 6). This

Vol. 15 No. 4 Apr. 2017

paper includes a part of the results in “The researchand development project for realization of the fifthgeneration mobile communications system” commissioned by The Ministry of Internal Affairs and Communications, Japan [11].
5. Future prospects
With the growing popularity of inexpensive yethighly convenient commercial products based onIEEE standard technology, wireless LANs havebecome essential as a means of connecting mobile
terminals to networks. However, a growing numberof use cases cannot be accommodated with standard
technology alone. To meet growing demand withlimited radio resources while providing exciting newservices, we think that there will be many more situations in the future where our technology will be
required. At NTT Access Network Service Systems
Laboratories, we will continue developing wireless
LAN solutions for ultra-high density environments,
and contributing to the realization of reasonably
priced 5G services that cooperate with wireless LAN
services.

6

Feature Articles

Unlicensed band platform

Database

Control engine

AP control

Association
control

5G wireless cell
Macrocellbase station

Wireless LAN AP

Improvement of interferencein unlicensed band

This paper includes a part of theresults in “The research anddevelopment project for realizationof the fifth-generation mobile
communications system”
commissioned by The Ministry ofInternal Affairs and Communications,Japan.

Wireless environment
information transmission
Low SHF bandsmall cell basestationHigh SHF bandsmall cell basestationMillimeter wave
wireless LAN AP
Selection of optimal
wireless access circuit

5G wireless terminal
SHF: super high frequency

Fig. 6. 5G mobile/wireless LAN cooperation.

References
[1]
[2]
[3]

[4]
[5]
[6]

[7]

7

ICT Research & Consulting Inc., “2015 Survey of Public Wireless
LAN Service Users,” 2015 (in Japanese).
M. Morikura and S. Kubota, “802.11 High-speed Wireless LAN Textbook (revised 3rd edition),” Impress R&D, 2008 (in Japanese).
Ministry of Internal Affairs and Communications, “Mobile Communication Traffic in Japan,” Information & Communications Statistics
Database (in Japanese).
http://www.soumu.go.jp/johotsusintokei/field/data/gt010602.pdf
The Fifth Generation Mobile Communications Promotion Forum(5GMF), “5G Mobile Communications Systems for 2020 and
Beyond,” 5GMF White Paper, Version 1.01, 2016.
Ministry of Internal Affairs and Communications, “Final Report fromthe Radio Policy Vision Council,” Dec. 2014 (in Japanese).
http://www.soumu.go.jp/main_content/000334592.pdf
B. A. H. S. Abeysekera, M. Matsui, Y. Takatori, and M. Mizoguchi,“Performance Evaluation of Network-controlled Channel Allocation
Scheme for IEEE 802.11 Wireless LANs,” IEICE Tech. Rep., Vol.
116, No. 202, CQ2016-72, pp. 129–134, 2016.
K. Kawamura, K. Ishihara, J. Iwatani, S. Shinohara, M. Akimoto, Y.
Inoue, T. Ichikawa, and Y. Takatori, “New Trends in Wireless LAN
and Cooperative Wireless LAN Technology,” NTT Technical Review,Vol. 15, No. 3, 2017.
https://www.ntt-review.jp/archive/ntttechnical.php?contents=
ntr201703fa3.html[8] M. Motegi, K. Hashiguchi, H. Kataoka, T. Kusabuka, Y. Tanaka, U.
Shibusawa, T. Yamazaki, and T. Ogawa, “2020 MICE—New Hospitality through Exhibitions × ICT,” NTT Technical Review, Vol. 14,
No. 12, 2016.
https://www.ntt-review.jp/archive/ntttechnical.php?contents=
ntr201612fa7.html[9] M. Matsui, A. Inoki, B. A. H. S. Abeysekera, T. Ichikawa, M. Mizoguchi, A. Kishida, A. Yamada, H. Morihiro, T. Asai, and Y. Okumura,“Wireless LAN Systems Cooperating with Mobile Circuits for 5G (1):Using Mobile Circuits to Increase System Capacity,” IEICE General
Conference, B-5-12, 2016 (in Japanese).
[10] A. Inoki, B. A. H. S. Abeysekera, M. Matsui, T. Ichikawa, M. Mizoguchi, A. Kishida, A. Yamada, H. Morihiro, T. Asai, and Y. Okumura,“Wireless LAN Systems Cooperating with Mobile Circuits for 5G (2):Using Beacon Signals to Estimate the Exposed State of APs,” IEICE
General Conference, B-5-13, 2016 (in Japanese).
[11] Ministry of Internal Affairs and Communications, The Radio Use
Web Site, Research and Dvelopment for Expansion of Radio Wave
Resource (in Japanese), http://www.soumu.go.jp/menu_
news/s-news/01kiban09_02000169.html

NTT Technical Review

Feature Articles

Author profile
Masato Mizoguchi
Senior Research Engineer, Supervisor, ProjectManager of Wireless Access Systems Project,
NTT Access Network Service Systems Laboratories.
He received a B.E. and M.E. in electrical engineering from Tokyo University of Science in1989 and 1991. Since joining NTT in 1991, he
has mainly been engaged in R&D of wirelessLANs including the IEEE 802.11a systems. He
received the Best Paper Award in 2000, 2011, and2016, and the Achievement Award in 2006 fromthe Institute of Electronics, Information andCommunication Engineers (IEICE). He is asenior member of IEICE and a member of IEEE.

Vol. 15 No. 4 Apr. 20178

Regular Articles

Low Latency Dynamic Bandwidth
Allocation Method with High
Bandwidth Efficiency for TDM-PON
Saki Hatta, Nobuyuki Tanaka, and Takeshi Sakamoto
Abstract

This article describes a low latency dynamic bandwidth allocation (DBA) method with high bandwidth
efficiency that is intended for use in campus area networks and mobile fronthaul based on TDM-PON(time division multiplexing passive optical network). These network systems require low latency ofunder 100 μs and high bandwidth efficiency. Our method involves only three steps for allocation andemploys an adaptive DBA cycle depending on the traffic load. The DBA cycle length, which is
proportional to the latency, can be minimized because the simple allocation steps are appropriate for
hardware implementation. Our DBA method automatically optimizes the cycle length to reduce thelatency and improve bandwidth efficiency. We implemented it on a 10-gigabit Ethernet passive optical
network (10G-EPON) media access control system-on-a-chip and evaluated the allocation results andthe latency on the 10G-EPON system. Our DBA achieved a minimum latency of 60 μs with priority
control and high bandwidth efficiency, depending on traffic.
Keywords: TDM-PON, DBA, low latency

Time division multiplexing passive optical network(TDM-PON) systems, such as gigabit passive optical
networks (GPON) [1] and Ethernet passive optical
networks (EPON) [2], have been widely deployed forfiber-to-the-home (FTTH) services because of theircost advantage over point-to-point systems. Point-topoint systems such as large campus area networks(campus-LANs) and mobile fronthaul (MFH) for thefifth-generation mobile communications network(5G) are still potential markets for TDM-PON [3, 4].
However, there are two problems with employing
TDM-PON for MHF and campus-LANs. The first is
the large upstream latency. In TDM-PON, dynamic
bandwidth allocation (DBA) must be implemented in
an optical line terminal (OLT) to avoid upstream data
collisions. DBA increases the latency. The second
problem is bandwidth efficiency. In general, thebandwidth efficiency decreases in proportion to the
reduction in latency, as shown in Fig. 1.
1

Reducing the grant processing time (GPT), whichis the time taken to process the DBA in the OLT, isimportant to reduce the latency. The handshaking
between the OLT and optical network units (ONUs)
derived using the status reporting (SR) method isHigh latency
High bandwidth efficiency
Bandwidth efficiency

1. Introduction

Low latency
Low bandwidth efficiency

Latency (DBA cycle)

Fig. 1. Latency vs. bandwidth efficiency.

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Regular Articles

DBA cycle
Grant processing
time (GPT)DBA cycle
Data arriveat OLT.

OLT
Request totransmitby REPORT

Requestgrantedby GATETransmit data
depending on grant.

ONU
Time

Latency
Data arriveat ONU.
OLT: optical line terminal
ONU: optical network unit

Fig. 2. Message exchange between ONU and OLT in SR-DBA.

shown in Fig. 2. When the OLT receives all of the
ONU’s REPORTs (a type of control message), it
begins to calculate the transmission time and starttiming for upstream data using a grant processor. The
transmission time is a time slot of a DBA cycle,
which is proportional to the latency. After the calculation, the OLT informs ONUs of these results by using
GATEs (another type of control message) to grant
each ONU’s data transmission. The length of the GPTdepends on the DBA method, and a complex method
increases it. The latency due to DBA for FTTH services is now on the order of milliseconds [5] becauseof its advanced software processing designed toachieve strict fairness.
To solve the two problems specific to TDM-PON,
we devised a low latency DBA method with greater
bandwidth efficiency. In addition, our DBA isequipped with a priority-control function. This isbecause in campus-LANs, the layer-two switch has tosupport priority control among its ports. Thus, priority control among ONUs is an important requirement
for TDM-PON-based campus-LANs.

optimize both latency and bandwidth efficiency
depending on the traffic load from ONUs.
Our DBA algorithm is shown in Fig. 3. It consistsof three simple steps. First, the grant processor allocates a shorter time that is equivalent to the requested
bandwidth (RBn, where n represents the identification
number of ONU) or a guaranteed bandwidth (GBn)for each ONU. Next, it allocates the unallocatedbandwidth (ΔUB1) for ONUs, requesting more bandwidth in descending order of priority. After the second allocation, in the high-traffic-load case, highbandwidth efficiency is achieved and the latency isdetermined as the maximum latency that has been set
as an initial configuration. Last, when excess bandwidth (ΔEB) is generated, that is, in the low-trafficload case, our DBA reduces the length of the DBA
cycle to achieve low latency because high bandwidth
efficiency is not demanded. The details of the threestep DBA method are explained as follows.
The DBA cycle, TDBA, is expressed as

2. Low latency DBA method to improve
bandwidth efficiency

where Trep and Tdata represent the time for sending
REPORTs and the time for sending user data, respectively. Trep depends on the number of linked ONUs, N(N = 1,2, …). It is expressed as

We propose a new DBA algorithm consisting of
three simple steps that is appropriate for hardware(HW) implementation. HW implementation makes it
possible to reduce the GPT and the latency. In addition, we adopt an adaptive DBA cycle to improve
bandwidth efficiency. The adaptive cycle length canVol. 15 No. 4 Apr. 2017

TDBA = Trep + Tdata,

Trep = BOH × N,

(1)

(2)

where BOH represents the burst overhead time,
which is determined by the optical transceiver ON/
2

Regular Articles[High-traffic-load case]
DBA cycle: TDBA

DBA cycle: TDBA
Tdata_max

Trep
#1

#2

#3 #4

DBA cycle: TDBA

a

b

c

1
#1
a

#2 #3 #4
b c d

UB1

#1
a

d

#2
b

#3 #4
c d

3

2
Unusedbandwidth

Tdata_max

Trep

Tdata_max

Trep

Priority: a > b > c > d

UB1

TDBA = Trep + Tdata_max[Low-traffic-load case]

Unusedbandwidth

DBA cycle: TDBA

DBA cycle: TDBA
Tdata_max

Trep

#2

#3 #4

a

b

c

d

EB
Unusedbandwidth

Unusedbandwidth(a) 1st step

Tdata_max

Trep

#1

UB1

Shorten Tdata

#1
a

#2
b

EB
#3 #4
Unusedcd bandwidth

TDBA = Trep + (Tdata_max – EB)(c) 3rd step(b) 2nd step

Fig. 3. Proposed DBA.

OFF time and the sync time. It is fixed.
In the initial configuration of our DBA, Tdata_max,
four kinds of priority (a > b > c > d), and the GBn foreach ONU are set. Here, Tdata_max represents the
maximum length of Tdata. We can set an arbitrary
length of Tdata_max according to the system requirements. After the configuration has been set, when
REPORTs including accumulated data in ONUs
come to the OLT, the grant processor starts to allocate
a time slot for each ONU in Tdata as shown in Fig. 3.
First, as shown in Fig. 3(a), the grant processor calculates RBn using the accumulated data and allocates ashorter time that is equivalent to the GBn or RBn foreach ONU. The allocated time, namely, the grant
length for each ONU (GL1n) is expressed as
RBn < GBn GL1n = (Tdata − BOH × N) ×
GBn < RBn GL1n = (Tdata − BOH × N) ×

(RRB )nmax(3)(RGB ),
n

max

(4)

where R max represents the effective maximum
throughput between the OLT and ONUs, excluding
the overhead of line coding. The above allocation3

enables each ONU to always acquire the guaranteedbandwidth or more in one period of the DBA cycle.
When the sum of RBn for each ONU is larger than
the sum of GBn, the allocation is finished and the GBn
is allocated for each ONU. In contrast, when the sumof RBn for each ONU is smaller than the sum of GBn,unallocated bandwidth (ΔUBm, m = 1,2, …, where mrepresents the number of iterations until ΔUBm = 0) is
derived from the delta between the sum of RBn andGBn. Then, the second allocation starts in Fig. 3(b).
The grant processor allocates the ΔUBm for each
ONU requesting more bandwidth, in descendingorder of priority. This achieves priority control
among ONUs. The second grant length for each ONU(GL2n) is expressed as
ΔUBm > GL2n GL2n = (Tdata − BOH × N)
(RBn − GBn)
(5)
×
Rmax
(6)
ΔUBm < GL2n GL2n = ΔUBm
ΔUBm+1 = ΔUBm − GL2n.
(7)

(

)

When the grant processor finishes allocating all unallocated bandwidth, the second allocation ends, which
is for high-traffic-load cases. The grant length eventually conveyed to ONUs by GATEs is expressed as
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Grant processor
DBA SW
Initial setting
DBA HW
Requestcalculator

Grantcalculator

REPORTs
10G-EPON
MAC SoCGATEs
MPCP processor
MPCP frame

MPCP: Multi-Point Control Protocol
SW: software
HW: hardware

Fig. 4. Implementation of grant processor with our DBA.

GLn = GL1n + GL2n.

(8)

TDBA in the high-traffic-load case is expressed as
TDBA = Trep + Tdata_max.

(9)The latency is determined as the maximum latency
that has been set as an initial configuration. In contrast, in the low-traffic-load case, excess bandwidth(ΔEB) is generated after all ΔUBm allocations. ΔEB isexpressed as
ΔEB = ΔUB1 −GL2n.

(10)

Then the third step starts. The grant processor subtracts the time equivalent to ΔEB from Tdata_max. As aresult, TDBA in the low-traffic-load case is expressedas
TDBA = Trep + (Tdata_max − ΔEB).

(11)

The proposed DBA algorithm is appropriate for
implementation in HW because the simple calculations for three-step bandwidth allocation from Eqs.
(1) to (11) are repeatedly executed in each DBA
cycle. Therefore, it can greatly shorten the Tdata_max
length after the second step of allocation.

Vol. 15 No. 4 Apr. 2017

3. Experimental evaluation
We conducted an experiment in order to evaluate
our DBA technique. We describe here the experimentand results.
3.1 Implementation and experimental setup
To evaluate the allocation results and latency, we
implemented our DBA function in the grant processor on a 10-gigabit Ethernet passive optical network(10G-EPON) media access control (MAC) systemon-a-chip (SoC) [6] for the OLT as illustrated inFig. 4. A schematic of the experimental setup is
shown in Fig. 5. We utilized a 10G-EPON systemwith one OLT and five ONUs (ONUs#1–5). The local
area network (LAN) analyzer was connected to the
OLT-SNI (server node interface) and the ONU-UNI(user network interface) to measure throughput andgenerate RB n from the ONUs. In this system,
ONUs#1–4 were set to measure throughput and the
DBA cycle. ONU#5 was set to adjust ΔUB1, which
can be generated by adjusting RB5 of ONU#5.
In the experiment, as priorities, “a” was set to
ONU#1, “b” to ONU#2, “c” to ONU#3, and “d” to
ONU#4 and ONU#5. We set GBn (n = 1–4) at 500
Mbit/s. A burst overhead time was set to 3280 ns.
Upstream Ethernet-frame data of 1518 bytes weretransmitted from the LAN analyzer at 1000 Mbit/s,
which is equivalent to RBn (n = 1–4). We adjusted
4Regular Articles

UNI

UNI

ONU#1 (priority a)

REPORTs capture
DBA cycle measurement

ONU#2 (priority b)
OLT

UNI

SNI

ONU#3 (priority c)
Splitter

UNI

UNI

Proposed
DBA in
MAC SoC

LAN analyzer
Signal generation
Signal termination

ONU#4 (priority d)
ONU#5 (priority d)Unused bandwidth
generation

SNI: service node interface
UNI: user network interface

Fig. 5. Experimental setup.

3.2 Measured results
The maximum latency calculated from the DBA
cycle measurement is shown in Fig. 6. The result of
the DBA cycle measurement matches the theoreticalvalue. One can see that when the minimum setting ofTdata_max was 21 μs, the minimum latency of 60 μs wasachieved. This is because most of the processing of
our DBA is handled by HW.
The results of measuring throughput and DBA
cycle are plotted in Fig. 7 and Fig. 8. The throughput
51800
Theoretical

1500

Experimental
Latency (µs)ΔUB1 using ONU#5. To measure the DBA cycle, we
captured REPORTs from ONU#1 and investigated
the received interval, which is equivalent to the DBA
cycle.
First, to confirm the minimum latency utilizing the
proposed DBA, we calculated the maximum latencyfrom the measured DBA cycle in the high-traffic-loadcase when Tdata_max was set to 21, 216, 416, 816, or
1016 μs. The latency in the TDM-PON system istheoretically nearly equal to 1.5 DBA cycles [7].
Next, we confirmed the priority control by adjusting
the unallocated bandwidth using ONU#5 and measuring throughput for ONUs#1–4 after DBA allocation. Finally, we confirmed the automatically adjusted function by investigating the change in DBA cycle
length when ΔUB1 was adjusted. Tdata_max was set to1000 μs so that the initial bandwidth efficiency would
be more than 95%.

1200
900
600
Tdata_max = 21 µs
Latency = 60 µs

300
0

0

250

500
750
Tdata_max (µs)

1000Fig. 6. Maximum latency.

results match the theoretical values. When ΔUB1 = 0,in other words, when the sum of RBn (n = 1–5) was
larger than the sum of GBn (n = 1–5), all ONUs wereallocated the guaranteed bandwidth of 500 Mbit/s.
When ΔUB1 > 0 but ΔEB = 0, that is, in the hightraffic-load case, ΔUB1 was allocated to ONU#1 first,
because its priority was the highest among the ONUs,
and its throughput reached 1000 Mbit/s of RB1. After
that, ΔUB1 was allocated in descending order of priority. The length of the DBA cycle stayed constant.
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Regular Articles

Priority: ONU#1(a) > ONU#2(b) > ONU#3(c) > ONU#4(d)Throughput after allocation (Mbit/s)

1200
ONU#1 (theoretical)

ONU#1

1000

ONU#2 (theoretical)

ONU#2
800

ONU#3 (theoretical)

ONU#3

ONU#4 (theoretical)

600

ONU#4

ONU#1 (experimental)

400

EB > 0

ONU#2 (experimental)

200

Low
traffic load

ONU#3 (experimental)

High traffic load ( EB = 0)

ONU#4 (experimental)
0

0

500

1000

1500

Unallocated bandwidth,

2000

2500

UB1 (Mbit/s)

Fig. 7. Throughput measurement result after allocation.

1400
Low traffic load
( EB > 0)

DBA cycle (µs)

1200
1000
800

High traffic load
( EB = 0)

600
400
200
0

0

500

1000
2000
2500
1500
3000
Unallocated bandwidth, UB1 (Mbit/s)

3500

Fig. 8. DBA cycle length depending on traffic load.

On the other hand, when ΔEB > 0, that is, in the lowtraffic-load case, the throughput stayed constant at
1000 Mbit/s. The length of the DBA cycle automatically decreased as ΔEB increased. These results indicate that our method can automatically adjust the
DBA cycle length depending on the traffic load.
When the initial Tdata_max was set to 21 μs in the lowtraffic-load case, our DBA achieved low latency withhigh bandwidth efficiency.

The results of experiments showed that the minimum
latency was 60 μs or less owing to simple three-step
allocation and cooperation with HW on a 10G-EPON
MAC SoC. Moreover, they demonstrated that our
method automatically adjusts the DBA cycle lengthand the bandwidth efficiency depending on trafficload. These results show that our DBA can be used invarious networks employing TDM-PON, such as
future campus-LANs and 5G MFH.

4. Conclusion

References

We proposed a DBA method with an adaptive DBA
cycle depending on traffic load for a TDM-PON that
accommodates future campus-LANs or 5G MFH.
Vol. 15 No. 4 Apr. 2017

[1]
[2]
[3]

ITU-T Recommendation G.983.4, 2001.
IEEE Std 802.3av, 2009.
NTT, “Low-cost and High-bandwidth Internal LAN System,” N-11,
NTT R&D Forum 2014, Tokyo, Japan, Feb. 2014.

6

Regular Articles

[4]

[5]
[6]

http://www.ntt.co.jp/RD/active/201402/en/nw/pdf/N-11_e.pdf
N. Shibata, T. Tashiro, S. Kuwano, N. Yuki, J. Terada, and A. Otaka,“Mobile Front-haul Employing Ethernet-based TDM-PON System
for Small Cells,” Proc. of Optical Fiber Communication Conference(OFC), Los Angeles, CA, USA, Mar. 2015, doi:10.1364/OFC.2015.
M2J.1.
T. Tatsuta, N. Oota, N. Miki, and K. Kumozaki, “Design Philosophy
and Performance of a GE-PON System for Mass Deployment,” J. Opt.
Netw., Vol. 6, No. 6, pp. 689–700, 2007, doi:10.1364/JON.6.000689.
M. Urano, T. Kawamura, S. Ohteru, H. Suto, K. Kawai, R. Kusaba, N.

Saki Hatta

Researcher, Fixed Mobile Convergence Device
Development Project, Metro-Access Network
Device Project, NTT Device Innovation Center.
She received a B.S. and M.S. in materials engineering from Tokyo Institute of Technology in2009 and 2011. She joined NTT Microsystem
Integration Laboratories in 2011, where she conducted research on digital devices for opticalaccess networks. She is now with the NTT
Device Innovation Center. She is engaged indeveloping a hardware accelerator and its algorithm for the TDM-PON system. She is a member of the Institute of Electronics, Information
and Communication Engineers (IEICE).

[7]

Miura, J Kato, A. Miyazaki, T. Hatano, S. Yasuda, N. Tanaka, S.
Shigematsu, M. Nakanishi, and T. Shibata, “The 10G-EPON OLT and
ONU LSIs for the Coexistence of 10G-EPON and GE-PON toward
the Next FTTH Era,” Proc. of 2011 IEEE Symposium on VLSI
Circuits, Honolulu, HI, USA, pp. 132–133, June 2011.
T. Tashiro, S. Kuwano, J. Terada, T. Kawamura, N. Tanaka, S.
Shigematsu, and N. Yoshimoto, “A Novel DBA Scheme for TDMPON based Mobile Fronthaul,” Proc. of OFC, San Francisco, CA,
USA, Mar. 2014, doi:10.1364/OFC2014.Tu3F.3.

Takeshi Sakamoto

Senior Research Engineer, Supervisor, Project
Leader of Fixed Mobile Convergence Device
Development Project, Metro-Access Network
Device Project, NTT Device Innovation Center.
He received a B.E. and M.E. in electronicengineering from Kyoto University in 1994 and1996. He joined NTT Opto-Electronic Laboratories in 1996. He is currently with NTT Device
Innovation Center, where he is involved in thedevelopment of digital devices for optical accessnetworks. He is a member of IEICE.

Nobuyuki Tanaka

Senior Research Engineer, Supervisor, Fixed
Mobile Convergence Device Development Project, Metro-Access Network Device Project, NTT
Device Innovation Center.
He received a B.E., M.E., and Dr.Eng. from
Shizuoka University in 1989, 1991, and 1999. In
1991, he joined NTT Interdisciplinary ResearchLaboratories. Since then, he has been researchingand developing devices for optical communication systems. He is a member of IEICE.

7

NTT Technical Review

Global Standardization Activities

Report on ITU Telecom World 2016
and ITU Kaleidoscope 2016
Hideyuki Iwata, Kazuhide Nakajima, and Noriyuki Araki
Abstract

ITU Telecom World 2016 and the eighth ITU Kaleidoscope academic conference, both of which areorganized by the International Telecommunication Union (ITU), took place November 14–17, 2016, at
the IMPACT Exhibition and Convention Center, Bangkok, Thailand. With the demise of His Majesty
King Bhumibol Adulyadej of Thailand in October, ITU Telecom World was formally opened in a solemn
atmosphere by Her Royal Highness Princess Maha Chakri Sirindhorn, second daughter of the late king.
This article gives an overview of the exhibits and discussions at the ITU Telecom World and the accompanying Kaleidoscope academic conference.
Keywords: ITU Telecom World, ITU Kaleidoscope, ICT

1. Overview of ITU Telecom World 2016
ITU Telecom World 2016 was a four-day event
organized by the International Telecommunication
Union (ITU) and attended by some 8800 participants.
It brought together some 250 exhibitors from 37
nations and 173 speakers from 56 nations. Over 330
information and communication technology (ICT)
leaders from 90 countries, representing both the public and private sectors, took part in the discussions.
 verview of roundtables and other main
1.1 O
meetings
Following the opening address by Her Royal Highness Princess Maha Chakri Sirindhorn, ITU Secretary-General Houlin Zhao, the Prime Ministers of
Luxembourg and Vanuatu, the Crown Prince of
Tonga, the Deputy Prime Minister of Thailand, andothers gave speeches. In the morning of Day 2, an
Economic and Industry Roundtable was held withsenior executives of telecommunications operators,
vendors, and financial organizations in attendance.
In the afternoon of Day 2, a Ministerial Roundtable
took place with participation by Thailand, Vanuatu,
Bahamas, Bangladesh, Belarus, Cambodia, Côte
d’Ivoire, Samoa, Hungary, Iran, Japan, Nigeria, andSwitzerland. The meeting was chaired by the Deputy
1

Prime Minister and Acting Minister of Digital Economy and Society of Thailand. Representing Japan
was Vice-Minister for Policy Coordination Shigeki
Suzuki. He stressed the importance of strengthening
access networks (including making overseas investments), pursuing innovation using Internet of Things(IoT) and big data, and ensuring the security and freeflow of information.
1.2 Overview of exhibition
There were 14 country pavilions—7 from Africa(Kenya, Ghana, Rwanda, Nigeria, Madagascar, Zimbabwe, and Senegal), 6 from Asia, the host region(Iran, Japan, China, South Korea, Malaysia, andThailand), and Azerbaijan. Exhibitors in the Japan
Pavilion were NTT Communications, Internet Initiative Japan, Japan Battery Regeneration, National
Institute of Information and Communication Technology (NICT), and Nextech. Japanese exhibitors in
the ITU Telecommunication Standardization Sector(ITU-T) booth were NEC, OKI, NICT, and the Telecommunication Technology Committee. In the NTT
Communications booth, NTT Communications Thailand, the company’s local subsidiary, exhibited information on its datacenters. That booth also incorporated exhibits by NTT Security and NTT DATA
(Photo 1). Nextech, a Hokkaido-based company,
NTT Technical Review

Global Standardization Activities

Photo 1. NTT Communications exhibit at Japan Pavilion.

Photo 2. Greeting by Chaesub Lee, the director of TSB.

which exhibited a Wi-Fi*1 access point system with asolar panel attached, received an SME *2 award.
Occupying 30% of the exhibition floor area, the Thailand pavilion exhibited the ICT policies of its ministries, agencies, and research institutes, including the
National Broadcasting and Telecommunications
Commission, Thailand Post, the Ministry of Scienceand Technology, the Ministry of Digital Economy
and Society, and the Defense Technology Institute.
Also on show were smart solutions developed bytelecommunications operators including AIS, CAT,dtac, TOT, and True. In addition, there were exhibits
by a number of local SMEs, indicating the steadyproliferation of ICT-related enterprises in Thailand.

2.1 Opening ceremony and keynotes
In the opening ceremony, welcoming speeches
were given by speakers from the host country: Virasak Kittivat, Principal Advisor for Foreign Affairs,
Ministry of Digital Economy and Society, and Supot
Tiarawut, Advisor to the President of Chulalongkorn
University. Mr. Tiarawut spoke on behalf of Bundhit
Eua-arporn, President of Chulalongkorn University
and also the ITU Kaleidoscope 2016 General Chairman. These speeches were followed by a greeting
remark by Chaesub Lee, Director of ITU’s Telecommunication Standardization Bureau (TSB), the organizer of ITU Telecom World (Photo 2).
There were three keynote addresses. Prof. Dr.-Ing*3
Thomas Wiegand of the Fraunhofer Heinrich Hertz
Institute, Germany, reported on research and development (R&D) trends in machine learning. He spoke
about concerns regarding the increase in video transmission traffic, the use of video coding compression
technology to reduce the volume of data transfers,
and the research activities aimed at reducing power
consumption in communications. He also touched on
future technical trends and went on to discuss different fields to which machine learning can be applied,
including the application of IMT-2020 (5G) to driverless vehicles, reduction of delay time through automation of mobile base station switching, and theapplication of machine learning to big data.
Mr. Hossein Moiin, Executive Vice President andChief Technology Officer for Nokia Mobile Networks, noted that Nokia has defined environmental

1.3 Next event
ITU Telecom World 2017 will be held September
25–28, 2017, in Busan, South Korea.
2. Overview of ITU Kaleidoscope 2016
In conjunction with ITU Telecom World 2016, the
ITU Kaleidoscope academic conference was held
November 14–16, 2016. The objective of the conference was to understand and discover standardization
technologies and needs that ITU should consider incoming years by examining research on informationand telecommunication technology from different
perspectives from an early stage. The main theme ofthis eighth conference was “ICTs for a Sustainable
World.” It was attended by some 100 persons from 21
countries. There were 25 presentations: 19 lecturesand 6 poster presentations.

Vol. 15 No. 4 Apr. 2017

*1 Wi-Fi is a registered trademark of Wi-Fi Alliance.
*2 Small- and medium-sized enterprises, startup enterprises, andventure capital enterprises.
*3 Dr.-Ing: Doctor of Engineering

2Global Standardization Activities

indicators for its entire production cycle. He also
introduced the future goals and direction of the environmental aspect of his company’s R&D, which hesaid was founded on three guiding principles: toenhance quality of life, protect the environment, andrespect humanity through further use of IoT. The
BBC screened a video on its activities addressing
environmental issues such as global warming and theneed to reduce carbon dioxide emissions. The video
explained the trade-off between the number of viewers of broadcast communications and the environmental impact, and addressed the issue of the environmental impact of travel for program production.
2.2 General sessions
There were six general sessions with six distinct
themes: the role of ICT in environmental conservation, standardization of services and quality, efficientfrequency utilization, network innovation, service
development, and sustainability.
The use of wireless links in coastal fishing in India
was introduced in the session on the role of ICT inenvironmental conservation. Varying usage fees
according to the quality of the communications service was proposed in the session on standardizationof services and quality. The session on efficient frequency utilization focused on methods of frequency
resource assignment for device-to-device systems
that use wireless links. In the session on network
innovation, it was proposed to execute delay management and to place a caching function in all network
elements. The need for remote medical care andremote rehabilitation in aging societies was advocated in the session on service development. The needfor standards in relation to privacy and the importance of wireless communication standards fordrones were reported in the session on sustainability.
Kazuhide Nakajima (co-author of this article) of
NTT Access Network Service Systems Laboratories
presented a paper entitled “Space Division Multiplexing Technology: Next-generation Optical Communication” [1]. He introduced a multi-core fiber,consisting of a relatively small number of cores, thatis compatible with a conventional G.652 single-mode
fiber and stated that the development of this opticalfiber was already at an advanced stage where it is possible to hold concrete discussions on standardizationand commercial development.

3

Photo 3. K azuhide Nakajima (center) receiving a Best
Paper Award.

2.3 Best Paper Award
The Best Paper Award review committee for thisacademic conference evaluated the content and presentation of each paper and selected three papers toreceive awards. One went to the above-mentioned
paper on space division multiplexing technology(Photo 3).
2.4 Looking ahead
With its membership exceeding 100 universities
and other institutions, ITU Academia sees its activities expanding. The restrictions on confining thescope of its activities to ITU-T, ITU-R (ITU Radiocommunication Sector), and ITU-D (ITU Telecommunication Development Sector) was lifted in 2015.
Today, academia members can participate in any ITU
meetings without restriction. This was a boon to themembers because it enables them to obtain information and enables their junior personnel to gain experience in international activities. That is why membership has been growing steadily. At WTSA-16 (World
Telecommunication Standardization Assembly2016), held in November 2016, a resolution encouraging academia activities was adopted. It is expectedthat Kaleidoscope will continue to play a liaison role
between ITU and academia.
Reference[1]

K. Nakajima, T. Matsui, K. Saito, T. Sakamoto, and N. Araki, “Space
Division Multiplexing Technology: Next-generation Optical Communication,” Proc. of ITU Kaleidoscope 2016, pp. 67–73, 2016.

NTT Technical Review

Global Standardization Activities

Hideyuki Iwata

Senior Research Engineer, Supervisor,
Research and Development Planning Department, NTT.
He received a Ph.D. in electrical engineeringfrom Yamagata University in 2011. From 1993 to
2000, he conducted research on high-density andaerial optical fiber cables at NTT Access Network Service Systems Laboratories. Since 2000,
he has been responsible for standardization strategy planning for NTT research and development.
He has been a delegate of International Electrotechnical Commission (IEC) Subcommittee 86A(optical fiber and cable) since 1998 and of the
ITU-T Telecommunication Standardization
Advisory Group since 2003. He is a vice-chair of
the Expert Group on Bridging the Standardization Gap in the Asia-Pacific Telecommunity
Standardization Program Forum. In 2004, hereceived an award from the IEC Activities Promotion Committee of Japan for his contributions
to standardization work in the IEC.

Noriyuki Araki

Senior Research Engineer, Access Media Project, NTT Access Network Service Systems Laboratories.
He received his B.E. and M.E. in electrical andelectronic engineering from Sophia University,
Tokyo, in 1993 and 1995. He joined NTT AccessNetwork Service Systems Laboratories in 1995,
where he researched and developed operationand maintenance systems for optical fiber cable
networks. He has been contributing to standardization efforts in ITU-T SG6 since 2006. He was
the rapporteur of Question 6 in ITU-T SG6 from2006 to 2008 and the rapporteur of Question 17
in ITU-T SG15 from 2008 to 2012. He also
served as the chairman of the ITU-T Focus
Group on Disaster Relief Systems and Network
Resilience and Recovery. He has been a vicechair of ITU-T SG15 since 2013. He also contributes to the activities of IEC TC86 (TechnicalCommittee 86: Fibre optics). He received the
ITU-AJ award from the ITU Association ofJapan in 2012. He is a member of IEICE.

Kazuhide Nakajima

Senior Research Engineer, Supervisor (SeniorDistinguished Researcher) and Group Leader of
NTT Access Network Service Systems Laboratories.
He received an M.S. and Ph.D. in electricalengineering from Nihon University, Chiba, in
1994 and 2005. In 1994, he joined NTT AccessNetwork Service Systems Laboratories, where
he engaged in research on optical fiber design
and related measurement techniques. He is also
acting as the rapporteur of Question 5 in ITU-T
Study Group (SG) 15. Dr. Nakajima is a memberof the Institute of Electronics, Information andCommunication Engineers (IEICE), the Instituteof Electrical and Electronics Engineers (IEEE),
and the Optical Society of America.

Vol. 15 No. 4 Apr. 20174

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

Case Study of Bolt Corrosion in
Remote Subscriber Module-Feeder
Point
Abstract

This article describes causes of and countermeasures to corrosion in bolts used for securing RSBM-F(remote subscriber module-feeder point) equipment. This is the thirty-ninth article in a series on telecommunication technologies. This contribution is from the Materials Engineering Group, Technical
Assistance and Support Center, Maintenance and Service Operations Department, Network Business
Headquarters, NTT EAST.
Keywords: RSBM-F, bolt corrosion, countermeasures to corrosion

1. Introduction
Today’s information and communication services
are supported by various facilities including radio
towers, utility poles, conduits, manholes, and tunnels.
Among these, the remote terminal box (RT-BOX) andremote subscriber module (RSBM) play importantroles in accommodating and multiplexing public andleased circuits and connecting them using opticalfiber to NTT buildings. In particular, the remote subscriber module-feeder point (RSBM-F) has been
installed at wiring points with the aim of converting
metal cables to optical fiber. This equipment isinstalled outdoors and is therefore continuously
exposed to a variety of environmental conditions suchas wind, rain, and airborne salt. This makes periodic
inspection of such facilities all the more important.
The RSBM-F is subject to inspections just as withother NTT facilities, and the facility inspection manual includes checks for abnormal operation of the
RSBM-F main unit as well as other inspection items
such as equipment doors and covers. However, noparticular inspection method is specified for the steelbolts used to secure the RSBM-F equipment to theground, and since these bolts are situated in locations
that cannot be viewed from outside the equipment,
they can be overlooked at the time of an inspection.
1

These steel bolts are made of iron and therefore naturally generate concerns about corrosion-related deterioration due to the effects of the surrounding environment. Bolts that are deteriorating because of corrosion lose their ability to safely secure the equipment, so countermeasures are necessary to maintaintheir strength.
The Materials Engineering Group of the Technical
Assistance and Support Center has investigated pastoccurrences of bolt corrosion in RSBM-F equipment.
In this report, we introduce a case study of bolt corrosion in RSBM-F and describe its causes and countermeasures.
2. RSBM-F configuration
An RSBM-F consists of a main unit, pedestal, andbase (Fig. 1). The main unit has upper and lower sections. The upper unit contains communication wiring,whereas the lower unit does not. The pedestal is asteel component used for securing the main unit to theconcrete base.
There are two doors for maintenance purposes on
the side of the RSBM-F (indicated by the coloredrectangles on the left side of Fig. 2). The door to theupper section of the main unit that houses communication wiring includes packing that hinders the inflow
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Practical Field Information about Telecommunication Technologies

Main unit

Pedestal
Base

Fig. 1. External view of RSBM-F.

RSBM-F cross section

Upper section
has packing
Path of penetrating
rainwater etc.

Main unit

No packing
Pedestal

Bolts

Base

Fig. 2. RSBM-F configuration diagram.

of moisture such as rainwater or snowmelt from theoutside. In contrast, the door to the lower section of
the main unit, which houses no communication wiring, does not include packing. Opening the lower
door brings a bolt into view (Fig. 2, right; Fig. 3).
This bolt secures the main unit to the pedestal and ispositioned in an easy-to-reach location. There is alsoa bolt beneath the above bolt for securing the pedestal
to the concrete base (Fig. 2, right). This bolt, however, is situated in a recessed location, making its maintenance quite difficult.

Vol. 15 No. 4 Apr. 2017

3. Causes of bolt corrosion
Although inexpensive and high-strength material
known as carbon steel is now commonly used forsteel bolts, it is more susceptible to corrosion compared with the stainless steel used for the RSBM-F
enclosure.
Because the door to the lower section of the main
unit does not include packing, moisture such as rainwater or snowmelt can penetrate the main unit fromthat section (right side of Fig. 2). Moreover, because
this door is normally closed, any moisture that penetrates this section cannot easily evaporate due to poor
ventilation and shaded conditions. Thus, if such2

Practical Field Information about Telecommunication Technologies

RSBM-F cross section

Main unit

Bolt securing main
unit to pedestal
Pedestal
Base

Fig. 3. Example of RSBM-F bolt corrosion.

RSBM-F cross section

Path of penetrating
rainwater etc.

Block penetration of rainwater
etc. with waterproofing tape.
Replace with stainlesssteel bolts to inhibit
bolt corrosion.

Upper section
has packing
Main unit

No packing
Pedestal
Base

Fig. 4. Countermeasures to bolt corrosion.

moisture from the outside gets into the area surrounding the bolt, it will tend to accumulate, thereby hastening bolt corrosion. In addition, RSBM-F equipment installed in coastal regions may suffer from thepenetration of saline matter from the ocean, while
those installed along highways in regions with heavy
snowfall may be affected by the penetration of chloride from snow-melting agents. Chemical solutions
containing chloride are highly conductive, promoting
the ionization of steel and accelerating corrosion. In
particular, if corrosion of the bolt head progresses toa point of layered rusting, the bolt may expand andcrack and then start to crumble as it loses its strength,
making it difficult to remove (Fig. 3).
4. Countermeasures to bolt corrosion

fixing ability of the bolt begins to deteriorate, theequipment runs the risk of shifting from its original
position, and in the worst case, collapsing. Countermeasures to corrosion are therefore needed. We consider here two corrosion countermeasures, one on theequipment side and one on the bolt side (Fig. 4).
The countermeasure on the equipment side is tostop the moisture from penetrating the equipment.
This can be accomplished, for example, by affixing
waterproofing tape to the gaps surrounding the lower
door to block the path of moisture.
The countermeasure on the bolt side, meanwhile, isto replace the bolt material with something that ismore corrosion-resistant. This could be stainless steel(SUS430, SUS304, etc.), which would inhibit bolt
corrosion.

If bolt corrosion progresses to the extent that the3

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Practical Field Information about Telecommunication Technologies

RSBM-F cross section

BackingplatesMain unit

Pedestal
Base

Fig. 5. Proposed technique of using backing plates to provide screw holes for securing bolts.

5. Future bolt corrosion countermeasures
Presently, no specific methods for inspecting
RSBM-F steel bolts are described in facility inspection manuals, but it is nevertheless important that they
be inspected together with other equipment inspection work. That is, when carrying out an RSBM-F
inspection, the maintenance door on the side of themain unit should be opened and the state of the bolts
visually checked. If corrosion is observed on a bolt,that bolt should then be replaced with a new one.
Additionally, the use of stainless-steel bolts is recommended in order to suppress bolt deterioration bycorrosion. However, if bolt corrosion at the time of avisual inspection has progressed as far as that shownin Fig. 3, it will be difficult to remove that bolt using
an ordinary wrench. In such cases, a commerciallyavailable rusted-bolt removal tool can be used, or amethod of destroying the bolt itself with a hammer orother tool to extract it can be considered.
There are cases, however, in which a corroded bolt
cannot be replaced by the above methods or in which

Vol. 15 No. 4 Apr. 2017

the bolt connecting the pedestal and concrete basecannot be replaced because of its difficult-to-reachlocation. A technique that can be considered for suchsituations is to use backing plates applied to the outside of the RSBM-F enclosure to provide new screw
holes for securing bolts. We plan to conduct trials to
study the effectiveness of this approach (Fig. 5).
6. Conclusion
In this report, we described causes of and countermeasures to corrosion in bolts used for securing
RSBM-F equipment. Since bolt corrosion progresses
as a result of moisture penetrating the equipmentfrom the outside, it is necessary to either replace thebolts themselves with corrosion-resistant stainlesssteel bolts or to block the path of penetrating moisture. In future studies, we plan to examine methods
for removing substantially corroded and deformed
bolts and a method for providing new bolt-fixing
locations by using backing plates applied to the outside of the RSBM-F enclosure.

4

Information

Event Report: Tsukuba Forum 2016
Wataru Yamada, Keiji Okamoto, and Koji Ieda
Abstract

Tsukuba Forum 2016 was held on October 25 and 26. The theme of the forum was “Future Social
Infrastructure: Co-creating a Better Life with Valued Partners ~ Innovative Access Network to Actualize
the NetroSphere Concept.” This article gives a brief overview of the speeches and exhibits presented at
the forum.
Keywords: Tsukuba Forum, access network, NetroSphere

1. Introduction
The focus of Tsukuba Forum 2016 was transforming the access network of the future from a connecting network into a service platform that adds value todaily life. The main forum theme was “Future Social
Infrastructure: Co-creating a Better Life with Valued
Partners ~ Innovative Access Network to Actualize
the NetroSphere Concept.” In addition to NTT
Access Network Service Systems Laboratories (ASLabs), 111 organizations (Table 1) participated andpresented the latest research and development (R&D)
and technology trends. The organizations included
many from the NTT Group as well as member companies from the co-host organizations: the Information & Telecommunications Engineering Associationof Japan, the Communication Line Products Association of Japan, and the Communications and Information Network Association of Japan.
2. Overview of speeches
The keynote speech and special speech were given
at the Tsukuba International Congress Center on thefirst day. They were relayed from the main convention hall of the International Congress Center, which
was the main venue, to a venue at the NTT Tsukuba
Research and Development Center, with many audience members in attendance.

1

2.1 Keynote speech
Mr. Motoyuki Ii, Senior Executive Vice President,
Senior Executive Manager of Corporate Sales Promotion Headquarters from NTT EAST, gave a keynote speech entitled “NTT EAST Group Activities
Targeting Business Markets” (Photo 1).
First, he informed the audience of market trends,
including that the number of subscribers to the
FLET’S HIKARI optical broadband service is slowing down, that NTT EAST will shift its main target ofbusiness to the business user market rather than the
consumer market, that the churn rate is low, the unit
price is high, and that there is room for market expansion. He specifically discussed the idea of promoting
the adaptation of information and communication
technology (ICT) for small and medium enterprises,
which form 99% of the business market in Japan, by
combining various services utilizing an optical platform. He then stated that NTT EAST is now focusing
on expanding the lineup of services for business markets, mainly to security, cloud, and support services.
Moreover, NTT EAST is wholesaling optical services to various service providers as a new value creation
with the Hikari Collaboration Model, and he gave
examples of new services in which the services of
those companies are combined with optical services.
Mr. Ii also explained efforts to support the Hikari Collaboration collaborators by preparing various service
menus for a charge.
Next, he explained that the introduction of ICT tosmall and medium enterprises has been lagging
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Table 1. List of exhibitors.
NTT Group companies
NTT EAST CORPORATIONNTT EAST-MINAMIKANTOCORPORATIONNTT Infrastructure Network
Corporation
AIREC ENGINEERINGCORPORATIONNTT RENTAL ENGINEERING
CO., LTD.
NTT Broadband Platform, Inc.
NTT GEOSPACECORPORATION
NTT WEST CORPORATION
NTT FIELDTECHNO
CORPORATIONNTT Communications
Corporation
NTT Electronics Corporation
NTT Advanced Technology
Corporation
NIPPON CAR SOLUTIONS
CO., LTD.
NTT History Center ofTechnologies
Information &Telecommunications
Engineering Association ofJapan (ITEA)
EXEO TECH CORPORATIONKYOWA EXEO CORPORATION
Nippon COMSYS Corporation
MIRAIT Corporation
TOSYS CORPORATIONNDS CO., LTD.
C-Cube Corporation Ltd.
Hokuriku Denwa Kouji Co., Ltd
NIPPON DENTSU CO., LTD.
MIRAIT Technologies

Corporation
SOLCOM CO., Ltd.
Shikokutsuken Co., Ltd.
Seibu Electric Industry Co., Ltd.
SYSKEN Corporation
DAIWA DENSETSUCORPORATIONTTK Co., Ltd.
TSUKEN CORPORATIONCommunication Line
Products Association of
Japan
AICHI CORPORATIONASABA MANUFACTURING
CO., LTD.
OCC Corporation
Okano Cable Co., Ltd.
Kando Co., Ltd.
KYOEI HIGH OPT Co., Ltd.
JFE Metal Products &Engineering Inc.
JAPAN RECOM Ltd.
SHODENSHA CO., LTD.
SWCC SHOWA CABLE
SYSTEMS CO., LTD.
Suzuki Giken Co., Ltd.
SUDA SEISAKUSYO CO., LTD.
Sumiden Opcom, Ltd.
3M Japan Limited
Sumitomo Electric Industries,
Ltd.
SEIWA GIKEN INC.
SENSHU ELECTRIC CO., LTD.
DYDEN CORPORATIONDAITO DENZAI CO., LTD.
TADANO LTD.
Tsushin Kogyo Electric Wire &Cable Co., Ltd.
TOSHIN ELECTRIC CO., LTD.

behind large enterprises due to a lack of information
technology talent, and he introduced an actual cloudservices implementation as a case study to show how
it can contribute to pursuing the asset-light businessmodel as part of the effort to revitalize small businesses.
Mr. Ii also explained how NTT EAST supports
problem solving in order to address priority issues inJapan such as invigorating local economies. He thenintroduced in an easy-to-understand manner several
examples of the introduction of ICT in various fields,
including a minutes support system for local governments, a support system for disaster victims,
improvements to the education environment with
ICT, the science information network SINET 5, robot
services for long-term care facilities in the field ofVol. 15 No. 4 Apr. 2017

TOTSU-SOKENCORPORATIONSEI Optifrontier Co., Ltd.
NISHI NIPPON ELECTRIC
WIRE & CABLE CO., LTD.
NIPPON CONCRETE
INDUSTRIES CO., LTD.
Nippon Seisen Cable, Ltd.
Nippon Tsushin Denzai Co., Ltd.
Hakusan Mfg. Co., Ltd.
Fujikura Ltd.
Furukawa Electric Co., Ltd.
Masaru Industries, Ltd.
Milliken Japan G.K.
Dainichi Co. Ltd.
Hitachi Metals, Ltd.
Communications andInformation Network
Association of Japan (CIAJ)
Anritsu Corporation
NEC Corporation
NEC Networks & System
Integration Corporation
NEC Magnus Communications,Ltd.
Oi Electric Co., Ltd.
OSAKI ELECTRIC CO., LTD.
Oki Electric Industry Co., Ltd.
Seiko Solutions Inc.
NAKAYO, INC.
Hitachi, Ltd.
Viavi Solutions Inc.
FUJITSU LIMITED
Fluke Networks
HellermannTyton Co., Ltd.
MARUBUN CORPORATION
Mitsubishi Electric Corporation
Yokogawa Meters & Instruments
Corporation

ASAKURA FACTORY Co. Ltd.
IWABUCHI CORPORATION
Kawaguchi Electric Works Co.,Ltd.
Kiya Corporation
SANKOSHA CORPORATIONSANRITZ ELECTRONICS CO.,LTD.
SANWA DENKI KOGYO CO.,LTD.
TAIEI Manufacturing Co. Ltd.
Takacom Corporation
TAKACHIHO SANGYO CO.,LTD.
TOKAI COMMUNICATION
INDUSTRY CO., LTD.
TOMEI TSUSHIN KOGYO CO.,LTD.
NAGAMURA
MANUFACTURING CO., LTD.
NISSHIN ELECTRIC CO., LTD.
HACHIKO ELECTRIC CO., LTD.
Fukuoka Tsushin Kozai
Seisakusho Co., Ltd.
MIYOKAWA Manufacturing Co.
Ltd.
WATANABE CO., LTD.
Japan Telecommunications
Equipment and Materials
Manufacturers Cooperative
Association
Other companies
FXC Inc.
NTEC
SUNREC CO., LTD.
HARADA CORPORATIONMIKI Inc.

medical care and nursing care, big data analysis of
personal data to understand the preferences of international visitors, and smart agriculture, which uses
ICT in the primary industry field.
He also explained the latest network technology tosupport these solutions: high-speed, broadband metro
access connecting all 47 prefectures in Japan in a
100G full-mesh network. This technology is capableof reducing the amount of electricity and spacerequired by switching routes via remote control
operation and switching without optical/electric conversion, and it was operational even when a 300-optical-fiber cable was cut during the Kumamoto earthquake in April 2016. In addition, the use of drones for
rapid restoration in isolated areas and inspectionof facilities where visual checking is difficult was2

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Photo 1. K eynote speech (Mr. Ii, NTT EAST Senior
Executive Vice President).

Photo 2. S pecial speech (Mr. Inose, President & CEO of
NTT GEOSPACE).

introduced, and further expansion of this effort was
indicated as a future plan.
Finally, the case of a stadium solution in the works for2020 was introduced. Building a Wi-Fi* environment
and enhancing the stadium application will contributenot only to the inside of the stadium but also to the
shopping area in the vicinity. It was an enthusiastic
keynote speech that expressed an eagerness to comeup with solutions in various fields.

automatic agricultural maneuvering, and the introduction of Pokémon GO. While describing the relationship between technology development and theunderlying technology, Mr. Inose stated that various
innovations will arise from open innovation such as
cooperation with automobiles and home appliances.
He stated that NTT GEOSPACE too has to selfreform to “GEOSPACE 2.0,” change its way of making maps, provide various types of content according
to the requirements of various partners, and develop
novel services through open innovation.
Drawing on the domestic trends surrounding selfdriving cars, he explained the development of threedimensional (3D) spatial information infrastructureusing NTT GEOSPACE’s two-dimensional electronic map overlaid with road and lane networks. Overseas, HERE Corp. is leading the map adjustment
technology, and NTT GEOSPACE would like to consider joint developments with HERE in order toadvance into Asian markets in the future. He also
spoke about i-Construction, which the Ministry ofLand, Infrastructure, Transport and Tourism is working on to promote construction work using ICT, andtrends related to products and services for mass users.
Among those trends, he mentioned that the motivation of NTT GEOSPACE related to the social issues
facing Japan is to overcome such problems throughtechnical innovation and the development of a 3D
spatial information platform. Then, as an initiative of
GEOSPACE 2.0, he presented the ideas of distributing
content on the B2B2X (business-to-business-to-X)

2.2 Special speech
Mr. Takashi Inose, President and Chief Executive
Officer (CEO) of NTT GEOSPACE CORPORATION, gave a special speech entitled “Trends in Open
Innovation and the GEOSPACE 2.0 Initiative”(Photo 2).
Mr. Inose first introduced the geospace map thatNTT GEOSPACE currently provides. The map initially provided just two items of content—an electronic map and aerial photographs—but more content
has been launched in the five years since the map’s
establishment, most recently the cloud service andsatellite images distributed over the Internet. Mr.
Inose described an environment that will make themap easier to use by applying an application programming interface, and he also explained the data
composition and past efforts relating to the electronicmap.
Next, he envisioned technological innovation
trends. Since the emergence of various technologies
in 2010, it has been expected that a very large paradigm shift relating to development will occur after
2020, as evidenced by the advent of self-driving cars,
3*

Wi-Fi is a registered trademark of Wi-Fi Alliance.

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Information

model in cooperation with partners to ensure that
accuracy is maintained in line with market demand,
securing appropriate updates, and offering a userfriendly database. Examples of GEOSPACE 2.0
efforts related to data know-how logic and data measurement processing technology and its usage
scenarios were introduced, namely: 1) map/address
data + lot number registration change information to
support the management of communication facilities,2) 3D spatial information + meteorological and geological information to support facility disaster-prevention planning, 3) a foreign visitor tourism service,4) utilization of mobile mapping system (MMS) datafor infrastructure management, and 5) indoor positioning and indoor/outdoor seamless navigation. He
also presented three new technical development cases
related to new elemental technologies, namely: 1)
automatic DSM (digital surface model) generationfrom aerial photographs, 2) automatic change detection (small satellite imaging), and 3) automatic detection of topology from satellite/aerial photography.
Finally, Mr. Inose stated that the town he had
dreamed of 40 years ago will be realized if various
systems underground, on land, and in the air merge
with open data, artificial intelligence (AI), big data,
and the cloud, and that information on the experienceof the ecosystem that is being developed throughopen innovation could be dispatched to Asia and allover the world. This was an ardent speech that demonstrated strong feelings about attaining an ultrasmart society.
2.3 Global session
On the afternoon of the first day, a global session
was held at the NTT Tsukuba Research and Development Center. Two lectures were given on the trends ofoverseas fiber to the home (FTTH) by Mr. Peter
Macaulay, President of the FTTH Council AsiaPacific (Malaysia) and by Mr. Ivan Felipe Toledo
Medina, a representative of ETB (Colombia). It wasa valuable opportunity to learn more about the FTTH
deployment status throughout the world (Photo 3).
2.4 Workshops
A series of workshops was held on the second day,and these included lectures given by four project
managers from NTT Network Technology Laboratories and AS Labs (Photo 4).
(1) Workshop 1
Mr. Kimihide Matsumoto, Vice President, Executive Manager of the Network Architecture Innovation
Vol. 15 No. 4 Apr. 2017

Photo 3. G lobal session (Mr. Macaulay, President of FTTH
Council Asia-Pacific (left) and Mr. Felipe Toledo
Medina, ETB (right)).

Project from NTT Network Technology Laboratories, gave a lecture entitled “NTT R&D Activities
toward Smart and Flexible Network (the NetroSphere
Concept).” First, he analyzed the direction of R&D
for a future network on the basis of changes surrounding the current communication network. The future
network is expected to be a smart and flexible network able to respond flexibly and economically tovarious demands from different business partners andto unpredictable demands such as those arising fromthe Internet of Things (IoT). The future network isalso expected to support the Hikari Collaboration
Model. Mr. Matsumoto also explained NetroSphere,
NTT’s network concept for responding to the challenges of diversity and prediction difficulties. NTT
laboratories’ efforts to realize the NetroSphere concept include: 1) high-speed and highly reliable server
architecture (MAGONIA), 2) Multi-Service Fabric(MSF) transport network configuration technologythat achieves both scalability and economy, 3) Flexible Access System Architecture (FASA) that enables
modularization of network equipment, 4) advanced
operation technology utilizing AI, and 5) verificationof the NetroSphere concept (NetroSpherePIT).
(2) Workshop 2
Mr. Akihiro Otaka, Vice President, Executive Manager of the Optical Access Systems Project from AS
Labs, gave a lecture entitled “R&D Activities of
FASA: Flexible Access System Architecture.” He
first discussed the realization of the NetroSphere concept for the access network, which is the FASA concept announced in February 2016, and introduced a4

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Photo 4. W orkshop leaders (From left to right: Mr. Matsumoto, a project manager of NTT Network Technology
Laboratories, Mr. Otaka, Mr. Sasaki, and Mr. Mizoguchi, project managers of AS Labs).

white paper published in May the same year on the
FASA website [1]. FASA is a concept to achieve service provision by combining functionalized blocks
and to realize an access network in the virtualizationera. The cooperation between various organizations
to achieve global diffusion was also addressed. In
addition, the important points of this technology,
which include modularization of functions, interfaces
connecting the functions, the realization of functions
using software, and the accommodation of functions
on cloud services, were discussed. Finally, Mr. Otaka
explained that AS Labs is conducting R&D on FASA
focusing on a passive optical network (PON) systemthat accommodates a fifth-generation (5G) mobile
base station as the initial target.
(3) Workshop 3
Mr. Kiyoharu Sasaki, Senior Manager of the Optical Access Network Project from AS Labs, gave alecture entitled “Research and Development of Innovative Operation Technology for Access Network
Infrastructure.” First, he explained the concept of If
infrastructure could speak in an easy-to-understandmanner by presenting a performance involving a person wearing a telephone pole costume (known as“Mr. Paul,” Photo 5). This idea is centered on theutilization of MMS and cars to acquire point clouddata and image data. The telephone pole of the NTTowned infrastructure is then converted into a 3Dmodel in order to automatically detect abnormalitiesof the pole such as a tilt or insufficient ground clearance of the cable. He also spoke of how in the future
it will be important to review operation tasks by com5

Photo 5. P erformance with telephone pole character “Mr.
Paul.”

bining various technologies such as IoT, augmented
reality, image analysis, AI, and machine learning. He
also briefly discussed the importance of developing
the capabilities of field personnel and issued a call for
NTT—as a company that provides social infrastructure services—to contribute to the maintenance of asafe and secure social infrastructure. Finally, heemphasized the need to renovate the access networkwith FASA and the new ground design of the opticalfiber infrastructure as part of efforts to improve theoperability and flexibility of access facilities while
maximizing the utilization of existing facilities.

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Photo 6. Main venue.

Photo 7. Outdoor exhibition zone.

(4) Workshop 4
Mr. Masato Mizoguchi, Senior Manager of the
Wireless Access Systems Project from AS Labs, gave
a lecture entitled “Wireless Access Technologies to
Enable a Variety of Services.” First, he explained the
problem with the current wireless local area network(LAN), which is that sufficient communication quality cannot be achieved in an environment where wireless
LAN devices are densely located. Then he discussed
the technology that will be used to solve this problem
and to further expand the wireless service—cooperative wireless LAN technology that improves throughput and stabilizes traffic to enhance the quality of user
experience and that is aimed at utilizing wireless
LAN for 5G mobile access. In the future, cooperative
wireless LAN architecture will continue to be developed in order to manage wireless LAN from the network side and to build a wireless LAN service platform capable of providing various wireless services.
The elemental technologies necessary for this realization were explained, and the schedule was clarified.

a special exhibition zone (divided into two areas) as
well as regular zones I, II, and III. The exhibits heldin the four zones are described below.
(1) Special exhibition zone
Special exhibition zone I: Flexible Access Network
Technology focused on access network configuration
technology for quickly responding to various services; it has been a major topic of study recently and isdesigned to realize the NetroSphere concept. Recommended exhibits in this zone were those on FASA,
which is intended to meet the various requirements ofservice providers, and a PON system for the 5G
mobile network.
Special exhibition zone II: Innovative Facility
Inspection Technology featured inspection technology to innovate outdoor facility operations. The innovative technology included aerial facility inspection
technology using MMS that was demonstrated as arecommended exhibition (Photo 9).
(2) Zone I
On the theme of “Creation Technology,” we exhibited technologies that will contribute to the creationof new services in the future and to the creation of aprosperous life. Network technologies and opticaland wireless technologies that transmit diverse traffic
were the focus in this zone. In particular, we introduced multi-core optical fiber technology that is
evolving to achieve the extreme level of space utilization as a recommended exhibition.
(3) Zone II
The theme in this zone was “Protection and Support
Technology,” and the exhibits featured current services and operations designed to achieve this. Infrastructure technology, maintenance and operation, and3. Overview of exhibits
Exhibits from AS Labs and exhibits on the latest
technologies by co-sponsored organizations and NTT
Group companies were also held (Photos 6 and 7).
3.1 AS Labs
The exhibition area was divided into four zones inwhich a wide range of R&D results of AS Labs were
exhibited (Fig. 1). Information on recommended
exhibits was displayed to visitors in an easy-to-understand manner (Photo 8). The four zones consisted ofVol. 15 No. 4 Apr. 20176

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I: Flexible Access Network Technology
Specialexhibition zone II: Innovative Facility Inspection Technology
This zone introduces flexible access network technology to provide various services immediately
and innovative facility inspection technology to operate outdoor facilities effectively. We aredeveloping these technologies steadily and surely to realize the NetroSphere concept.
Zone I

Creation Technology

This zone introduces creation technology that contributes to the establishment of new services fora more affluent lifestyle in the future. It is focused on network technologies to accommodate
multiple services and optical wireless convergence technologies.
Zone II

Protection and Support Technology

This zone introduces protection and support technology that supports provisioning and current
service operations, focusing on infrastructure technology, fundamentals, maintenance, operation,and disaster recovery.
Zone III

Display of a model network

This zone visually introduces an overall picture of access network technologies (those alreadydeployed) in a physical sequence from an NTT building to a customer’s premises.

Fig. 1. Summary of NTT exhibition.

Photo 8. NTT exhibition zone.

Photo 9. NTT demonstration.

disaster countermeasure technologies were the focus inthis zone. In particular, technology to improve network
reliability by predicting pipe conduit damage fromearthquakes with high accuracy and annotation technology to add know-how information on user terminal
screens were introduced as recommended exhibitions.
(4) Zone III
An overall picture of the access network technologies was displayed as a model network from inside an
NTT building to a customer’s premises in an easy-tounderstand way with actual equipment.

3.2 I nformation & Telecommunications Engineering Association of Japan (ITEA)
Exhibitors affiliated with ITEA introduced theirefforts to improve quality and efficiency, and toachieve rapid equipment restoration in the event oflarge-scale disasters to realize a safe, secure, and reliable communications infrastructure. The exhibits
featured their acquired technologies, know-how
inheritance, and construction and maintenance of
optical access facilities.

7

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Information

3.3 C ommunication Line Products Association ofJapan
Exhibitors belonging to the Communication Line
Products Association of Japan introduced their latest
efforts, focusing on technologies and products related
to outdoor equipment, including optical and metal
cables and related equipment.
3.4 C ommunications and Information Network
Association of Japan (CIAJ)
Together with the Japan Industrial Association for
Telecommunications Equipment and Materials(Zentsukyo), exhibitors belonging to CIAJ presented
various products and solutions related to communication networks to realize a safe, secure, and prosperous
society.
3.5 NTT Group companies
To provide the best and most trusted services as avalue partner, NTT Group companies displayed thelatest technologies to contribute to the realization of asafe, secure, and prosperous society where people,
society, and the earth are connected through communication.
3.6 Events
Demonstrations and technical seminars by exhibitors were held at the AS Labs main venue and at an
outdoor venue, with many participants in attendance(Photo 10).
3.7 Free Wi-Fi trial
We collaborated with NTT Broadband Platform,
Inc. to conduct a free Wi-Fi trial within the main
venue of AS Labs. In the free Wi-Fi area, all of the
speeches were delivered by live streaming. The
speeches were also recorded on video, and when the
speeches were finished, the video was distributed. At
the Rest Station, a premium Wi-Fi service using
cooperative wireless LAN technology was deployed.
Visitors were able to experience wireless LAN technology under high-density conditions without having
to worry about congestion.

Photo 10. Technical seminar held by an exhibitor.

of the event, the second day was blessed with fineweather. About 9400 people including many customers from abroad participated in this forum; thus, Tsukuba Forum 2016 was a resounding success. Various
exhibits on the latest R&D and future trends of AS
Labs were received with high interest. A visitors’questionnaire was administered after the exhibition,and the responses indicated that 98% of participants
were satisfied with their experience. Overall, it was arewarding event that offered a place to share knowledge with the participating companies, including theco-host organizations, on the transformation of theaccess network that supports a high quality of life
brought on by the realization of the NetroSphere concept.
Acknowledgments
We thank the Information & Telecommunications
Engineering Association of Japan, the Communication Line Products Association of Japan, and theCommunications and Information Network Association of Japan for their support of Tsukuba Forum2016.
Reference

4. Conclusion[1]

Although there was light rain on the first afternoon

Vol. 15 No. 4 Apr. 2017

Website of FASA, http://www.ansl.ntt.co.jp/e/global/FASA/index.
html

8

Information

Wataru Yamada
Senior Research Engineer, Planning Section,
NTT Access Network Service Systems Laboratories.
He received a B.E., M.E., and Ph.D. from Hokkaido University in Japan in 2000, 2002, and2010. Since joining NTT in 2002, he has been
researching propagation characteristics of wideband access systems. From 2013 to 2014, he wasa visiting research associate at the Centre for
Telecommunications Research at King’s College
London, UK. He received the Young Researcher’s Award, the Communications Society Best
Paper Award, and the Best Paper Award from theInstitute of Electronics, Information and Communication Engineers (IEICE) in 2006, 2011,
and 2014. He is a member of IEICE and IEEE
(Institute of Electrical and Electronics Engineers).

Koji Ieda
Senior Research Engineer, Planning Section,
NTT Access Network Service Systems Laboratories.
He received a B.E. and M.E. in electronicengineering from Nagoya University, Aichi, in
1994 and 1996. In 1996, he joined NTT AccessNetwork Service Systems Laboratories, where
he has been conducting research on optical customer networks. Mr. Ieda is a member of IEICE.

Keiji Okamoto
Research Engineer, Planning Section, NTT
Access Network Service Systems Laboratories.
He received a B.S. and M.S. from Tohoku
University in 2003 and 2005. In 2005, he joined
NTT Access Network Service Systems Laboratories, where he has been engaged in research on
optical signal measurement. He is a member of
IEICE.

9

NTT Technical Review

Short Reports

NTT, Ruhr-Universität Bochum, andKobe University Develop a New
Cryptanalytic Technique to Improve
the Design of Lightweight Ciphers forInternet of Things
1. Research result
NTT, jointly with Ruhr-Universität Bochum andwith Kobe University, has developed a new cryptanalytic technique (the nonlinear invariant attack) thathelps improve the design and security of lightweightsymmetric-key ciphers, which are considered to play
an active part in the IoT (Internet of Things) era.
Most of the previous cryptanalysis techniques
assume unrealistic scenarios where adversaries haveopportunities to obtain encrypted data of plaintext
they deliberately choose, in terabytes. In contrast, the
new cryptanalytic technique, when applied to several
existing (lightweight) ciphers, recovers part of theplaintext from encrypted data in amounts smaller
than one kilobyte, under the condition that either theplaintext contains repetition or the same plaintext
gets encrypted multiple times. The new technique canbe used to greatly improve the design of lightweightciphers and to re-evaluate the security of other existing symmetric-key ciphers.
The paper reporting this research result [1] received
the distinction of being “Invited to the Journal of
Cryptology,” meaning that it was one of the top threepapers accepted at Asiacrypt 2016 (held in Hanoi,
Vietnam, December 4–8), a prestigious conference
organized by the International Association of Cryptologic Research.
2. Key facts
Linear cryptanalysis was published in 1993 andapplied to the Data Encryption Standard (DES),
which was essentially the world standard at that time,1

demonstrating the first cracking of DES by a computer. Linear cryptanalysis was applied to numerous
cryptographic primitives as a generic cryptanalytic
technique, and cryptographic primitives newly developed after the publication of linear cryptanalysis
were required to provide evidence of resistance tolinear cryptanalysis. Linear cryptanalysis, as thename suggests, linearly approximates nonlinear
behavior of cryptographic primitives. It has been along-standing open problem whether it is possible todevise a similar type of cryptanalysis using nonlinear(quadratic or higher) approximation rather than linear
approximation. A previous attempt in 1995 used nonlinear approximation to analyze input and output
parts of a cryptographic primitive, but no previous
attempts succeeded in cryptanalyzing an entire cryptographic primitive. Our new cryptanalytic technique,the nonlinear invariant attack, provides an answer tothe open problem for the first time.
The previously mentioned paper describes how the
nonlinear invariant attack is applied to SCREAM,iSCREAM, and Midori64. SCREAM and iSCREAM
are symmetric-key schemes submitted to CAESAR, acompetition to evaluate authenticated encryption(symmetric-key ciphers equipped with an integrity
check). Midori64 is a symmetric-key cipher published at Asiacrypt 2015. The key idea of the attack is
to identify a quadratic (hence, nonlinear) invariant
quantity associated with the nonlinear component of
the cipher called sbox and then to observe that thesum of the quadratic function (nonlinear approximation) applied to each sbox output also remains
unchanged through the linear part of the cipher wherea binary orthogonal matrix is used. When the attack is
NTT Technical Review

Short Reports

applied to SCREAM and iSCREAM, 32 bits of plaintext are instantly recovered from 33 blocks (one blockis 128 bits) of encrypted data, under the condition thatthe secret key is one of the 296 special keys (called“weak keys”) out of the entire 2128 key space. Whenapplied to Midori64 in most modes of operations
used in practice, for example in the CTR (counter)
mode, 32 bits of plaintext are instantly recoveredfrom 33 blocks (one block is 64 bits) of encrypted
data for 264 special keys out of the entire 2128 key
space.
3. Future plans

re-evaluate the security of other existing ciphers byapplying the nonlinear invariant attack and is also
pursuing cryptanalytic techniques for developing
secure cryptographic algorithms.
Reference[1]

Y. Todo, G. Leander, and Y. Sasaki, “Nonlinear Invariant Attack—
Practical Attack on Full SCREAM, iSCREAM, and Midori64,” Proc.
of Asiacrypt 2016, Part II, pp. 3–33, Hanoi, Vietnam, Dec. 2016.

For Inquiries
NTT Service Innovation Laboratory Group
http://www.ntt.co.jp/news2016/1612e/161201a.html

NTT Secure Platform Laboratories is continuing toVol. 15 No. 4 Apr. 20172

External Awards
The Commendation for Science and Technology by the
Minister of Education, Culture, Sports, Science and Technology, Prize for Science and Technology, Development
Category
Winner: Ryuichiro Higashinaka, NTT Media Intelligence Laboratories; Minoru Etoh, Yoshinori Isoda, and Takeshi Yoshimura, NTT
DOCOMO
Date: April 20, 2016
Organization: Ministry of Education, Culture, Sports, Science andTechnology

Published as: T. Asami, R. Masumura, H. Masataki, M. Okamoto,and S. Sakauchi, “Training Data Selection for Acoustic Modeling
Based on Submodular Optimization of Joint KL Divergence,” IEICE
Tech. Rep., Vol. 115, No. 184, SP2015-58, pp. 45–50, Aug. 2015.
FIT2016 Funai Best Paper Award
Winner: Yukihiro Bandoh, Seishi Takamura, and Atsushi Shimizu,
NTT Media Intelligence Laboratories
Date: September 8, 2016
Organization: The 15th Forum on Information Technology(FIT2016)

For their development of a voice agent service.
Best Paper Award
Winner: Go Irie and Hiroyuki Arai, NTT Media Intelligence Laboratories; Yukinobu Taniguchi, Tokyo University of Science
Date: June 2, 2016
Organization: The Institute of Electronics, Information and Communication Engineers (IEICE)
For “Hashing with Locally Linear Projections.”
Published as: G. Irie, H. Arai, and Y. Taniguchi, “Hashing with
Locally Linear Projections,” IEICE Trans. Information and Systems(Japanese Edition), Vol. J97-D, No. 12, pp. 1785–1796, Dec. 2014.
Excellent Paper Award
Winner: Harumi Kawamura, Salesian Polytechnic; Yasuhiro Yao,
Dimension Data; Shunichi Yonemura, Shibaura Institute of Technology; Jun Ohya, Waseda University; Akira Kojima, NTT Media Intelligence Laboratories
Date: June 18, 2016
Organization: The Institute of Image Electronics Engineers of Japan
For “Estimating Scene Illuminant Colors from the Color Images
Acquired by a Fixed Camera under Different Illuminations.”
Published as: H. Kawamura, Y. Yao, S. Yonemura, J. Ohya, and A.
Kojima, “Estimating Scene Illuminant Colors from the Color Images
Acquired by a Fixed Camera under Different Illuminations,” The
Journal of the Institute of Image Electronics Engineers of Japan, Vol.
43, No. 2, pp. 164–174, Nov. 2014.
IEICE ISS Young Researcher’s Award in Speech Field
Winner: Yusuke Ijima, NTT Media Intelligence Laboratories
Date: August 25, 2016
Organization: IEICE Information and Systems Society (ISS)For “Objective Evaluation of Synthetic Speech Using Association
between Dimensions within Spectral Features.”
Published as: Y. Ijima, T. Asami, and H. Mizuno, “Objective Evaluation of Synthetic Speech Using Association between Dimensions
within Spectral Features,” IEICE Tech. Rep., Vol. 115, No. 392,
SP2015-90, pp. 27–32, Jan. 2016.
IEICE ISS Young Researcher’s Award in Speech Field
Winner: Taichi Asami, NTT Media Intelligence Laboratories
Date: August 25, 2016
Organization: IEICE ISS
For “Training Data Selection for Acoustic Modeling Based on
Submodular Optimization of Joint KL Divergence.”

1

For “Encoding-oriented Video Generation Algorithm Based on
Control with High Temporal Resolution.”
Published as: Y. Bandoh, S. Takamura, and A. Shimizu, “Encodingoriented Video Generation Algorithm Based on Control with High
Temporal Resolution,” Proc. of FIT2016, RI-002, Toyama, Japan,
Sept. 2016.
FIT2016 Paper Award
Winner: Yuichi Sayama, Yukihiro Bandoh, Seishi Takamura, andAtsushi Shimizu, NTT Media Intelligence Laboratories
Date: September 8, 2016
Organization: FIT2016
For “Optimal Design of Adaptive Intra Predictors Based on Sparsity Constraint.”
Published as: Y. Sayama, Y. Bandoh, S. Takamura, and A. Shimizu,“Optimal Design of Adaptive Intra Predictors Based on Sparsity
Constraint,” Proc. of FIT2016, RI-003, Toyama, Japan, Sept. 2016.
Technical Committee Prize Paper Award
Winner: Hiroyuki Manabe, NTT DOCOMO; Munekazu Date andHideaki Takada, NTT Media Intelligence Laboratories; Hiroshi
Inamura, NTT DOCOMO
Date: October 3, 2016
Organization: The Industrial Lighting and Displays Committee,
Institute of Electrical and Electronics Engineers (IEEE) Industrial
and Applications Society (IAS)
For “Low Power Driving Techniques for 1-pixel Displays.”
Published as: H. Manabe, M. Date, H. Takada, and H. Inamura,“Low Power Driving Techniques for 1-pixel Displays,” Proc. of theIEEE IAS Annual Meeting 2015, Dallas, TX, USA, Oct. 2015.
Best Poster Award
Winner: Seishi Takamura, NTT Media Intelligence Laboratories
Date: December 1, 2016
Organization: The 31st Picture Coding Symposium of Japan and21st Image Media Processing Symposium (PCSJ/IMPS 2016)
For “Efficient Video Coding Based on Object Tracking.”
Published as: S. Takamura, “Efficient Video Coding Based on
Object Tracking,” PCSJ/IMPS 2016, P-2-16, Shizuoka, Japan, Nov.
2016.
Best Poster Award
Winner: Takayuki Sasaki, NTT Media Intelligence Laboratories
Date: December 1, 2016
Organization: PCSJ/IMPS 2016

NTT Technical Review

Papers Published in Technical Journals and Conference Proceedings

For “Accelerated Optimization of Nuclear Norm in Region Coding.”
Published as: T. Sasaki, “Accelerated Optimization of Nuclear Normin Region Coding,” PCSJ/IMPS 2016, P-3-20, Shizuoka, Japan, Nov.
2016.
Best Paper Award
Winner: Takahiro Suzuki, Sang-Yuep Kim, Jun-ichi Kani, Ken-Ichi
Suzuki, and Akihiro Otaka, NTT Access Network Service Systems
Laboratories
Date: December 7, 2016
Organization: Transmission, Access, and Optical Systems (TAOS)
Technical Committee, IEEE Communications Society
For “Real-time Demonstration of PHY Processing on CPU for
Programmable Optical Access Systems.”
Published as: T. Suzuki, S. Kim, J. Kani, K. Suzuki, and A. Otaka,“Real-time Demonstration of PHY Processing on CPU for Programmable Optical Access Systems,” 2016 IEEE Global Communications
Conference, Washington, DC, USA, Dec. 2016.
Outstanding Reviewer Award 2016
Winner: William J. Munro, NTT Basic Research Laboratories
Date: February 3, 2017
Organization: IOP PublishingThis award is given to reviewers for their expertise and outstanding
contribution to New Journal of Physics.
IDW/AD’16 Demonstration Award
Winner: Shin’ya Nishida, Takahiro Kawabe, Taiki Fukiage, andMasataka Sawayama, NTT Communication Science Laboratories
Date: February 10, 2017
Organization: The Institute of Image Information and Television
Engineers and the Society for Information Display
For “Animating Static Objects by Illusion-based Projection Mapping.”
Published as: S. Nishida, T. Kawabe, T. Fukiage, and M. Sawayama,“Animating Static Objects by Illusion-based Projection Mapping,”
IDW/AD’16 (The 23rd International Display Workshops in conjunction with Asia Display 2016), Sendai, Japan, Dec. 2016.
RSA Conference Award (Excellence in the Field of Mathematics)
Winner: Tatsuaki Okamoto, NTT Secure Platform Laboratories
Date: February 14, 2017
Organization: RSA Conference
For the last 30 years, he has been actively working in many areasof cryptography and has become a world leader in the field based on
his numerous fundamental solutions and other central contributions.

Papers Published in Technical Journals andConference Proceedings
Differential Contributions of GABA Concentration in Frontal and Parietal Regions to Individual Differences in Attentional Blink
K. Kihara, H. M. Kondo, and J. Kawahara
The Journal of Neuroscience, Vol. 36, No. 34, pp. 8895–8901,
August 2016.
Selective attention plays an important role in identifying transient
objects in a complex visual scene. Attentional control ability varies
with observers. However, it is unclear what neural mechanisms are
responsible for individual differences in attentional control ability.
The present study used the following attentional blink paradigm:
when two targets are to be identified in rapid serial visual presentation, the processing of the first target interrupts the identification of
the second one appearing within 500 ms after the first-target onset. It
has been assumed that the reduction of the second-target accuracy ismainly due to a transient inhibition of attentional reorienting from thefirst to the second target, which is modulated by the g-aminobutyricacid (GABA) system. Using magnetic resonance spectroscopy, weinvestigated whether individual variation of attentional blink magnitude is associated with GABA concentrations in the left prefrontal

Vol. 15 No. 4 Apr. 2017

cortex (PFC), right posterior-parietal cortex (PPC), and visual cortex(VC) of humans. GABA concentrations in the PFC were related
negatively to attentional blink magnitude and positively to the firsttarget accuracy. GABA concentrations in the PPC were positively
correlated with attentional blink magnitude. However, GABA concentrations in the VC did not contribute to attentional blink magnitude and first-target accuracy. Our results suggest that frontoparietal
inhibitory mechanisms are closely linked with individual differencesin attentional processing and that functional roles of the GABAergic
system in selective attention differ between the PFC and PPC.

Auditory and Visual Scene Analysis: an Overview
H. M. Kondo, A. M. van Loon, J. Kawahara, and B. C. J. Moore
Philosophical Transactions of the Royal Society B, Vol. 372,
20160099, January 2017.
We perceive the world as stable and composed of discrete objects
even though auditory and visual inputs are often ambiguous owing tospatial and temporal occluders and changes in the conditions of2

Papers Published in Technical Journals and Conference Proceedings

observation. This raises important questions regarding where andhow ‘scene analysis’ is performed in the brain. Recent advances fromboth auditory and visual research suggest that the brain does not
simply process the incoming scene properties. Rather, top-down
processes such as attention, expectations and prior knowledge facilitate scene perception. Thus, scene analysis is linked not only with theextraction of stimulus features and formation and selection of perceptual objects, but also with selective attention, perceptual binding andawareness. This special issue covers novel advances in scene-analysis
research obtained using a combination of psychophysics, computational modelling, neuroimaging and neurophysiology, and presents
new empirical and theoretical approaches. For integrative understanding of scene analysis beyond and across sensory modalities, we
provide a collection of 15 articles that enable comparison and integration of recent findings in auditory and visual scene analysis.

Auditory Multistability and Neurotransmitter Concentrations in the Human Brain
H. M. Kondo, D. Farkas, S. L. Denham, T. Asai, and I. Winkler
Philosophical Transactions of the Royal Society B, Vol. 372,
20160110, January 2017.
Multistability in perception is a powerful tool for investigating
sensory–perceptual transformations, because it produces dissociations between sensory inputs and subjective experience. Spontaneous
switching between different perceptual objects occurs during prolonged listening to a sound sequence of tone triplets or repeatedwords (termed auditory streaming and verbal transformations,
respectively). We used these examples of auditory multistability to
examine to what extent neurochemical and cognitive factors influence the observed idiosyncratic patterns of switching between perceptual objects. The concentrations of glutamate-glutamine (Glx)and g-aminobutyric acid (GABA) in brain regions were measured bymagnetic resonance spectroscopy, while personality traits and executive functions were assessed using questionnaires and response inhibition tasks. Idiosyncratic patterns of perceptual switching in the two
multistable stimulus configurations were identified using a multidimensional scaling (MDS) analysis. Intriguingly, although switching3

patterns within each individual differed between auditory streaming
and verbal transformations, similar MDS dimensions were extracted
separately from the two datasets. Individual switching patterns weresignificantly correlated with Glx and GABA concentrations in theauditory cortex and inferior frontal cortex but not with the personality traits and executive functions. Our results suggest that auditory
perceptual organization depends on the balance between neural excitation and inhibition in different brain regions.

Individual Differences in Visual Motion Perception and
Neurotransmitter Concentrations in the Human Brain
T. Takeuchi, S. Yoshimoto, Y. Shimada, T. Kochiyama, and H. M.
Kondo
Philosophical Transactions of the Royal Society B, Vol. 372,
20160111, January 2017.
Recent studies have shown that interindividual variability can be arich source of information regarding the mechanism of human visual
perception. In this study, we examined the mechanisms underlying
interindividual variability in the perception of visual motion, one of
the fundamental components of visual scene analysis, by measuring
neurotransmitter concentrations using magnetic resonance spectroscopy. First, by psychophysically examining two types of motion
phenomena—motion assimilation and contrast—we found that, following the presentation of the same stimulus, some participants perceived motion assimilation, while others perceived motion contrast.
Furthermore, we found that the concentration of the excitatory neurotransmitter glutamate-glutamine (Glx) in the dorsolateral prefrontal cortex (Brodmann area 46) was positively correlated with theparticipant’s tendency to motion assimilation over motion contrast;
however, this effect was not observed in the visual areas. The concentration of the inhibitory neurotransmitter g-aminobutyric acid had
only a weak effect compared with that of Glx. We conclude that
excitatory process in the suprasensory area is important for an individual’s tendency to determine antagonistically perceived visualmotion phenomena.

NTT Technical Review