NTT Technical Review

February 2017 Vol. 15 No. 2
Feature Articles: Improving Productivity in Software Development Using Macchinetta
FrameworkImproving Productivity of Software Development on the Macchinetta FrameworkImproving the Efficiency of Application Development Based on the Macchinetta Framework

Test Automation Technology to Promote Early and Frequent Releases of Software at Low Cost

A Quick Software Development Method for Improving Competitiveness of Services

Regular Articles
Graphene p-n Junction as an Electronic Beam Splitter

World’s Highest Density Optical Fiber for Space Division Multiplexing with Deployable
Reliability

Global Standardization Activities


Quality Estimation Technique for Video Streaming Services

Practical Field Information about Telecommunication Technologies

Fax Transmission Failure Analysis Method Requiring Multi-signal Analysis

Short ReportsExperimental Test of Macroscopic Realism Problem Using a Superconducting Flux Qubit

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

Feature Articles: Improving Productivity in Software
Development Using Macchinetta Framework

Improving Productivity of Software
Development on the Macchinetta
Framework
Hikaru Suzuki
Abstract

The NTT Software Innovation Center aims to provide high quality services in a timely manner while
reducing total cost of ownership. To achieve this goal, it is necessary to develop new software rapidly
and stably. This article introduces technology for improving the productivity of software developmenton the Macchinetta framework, which uses the same open source programs as conventional softwaredevelopment.
Keywords: improving productivity, reducing TCO, application framework

1. Introduction
The changes in the revenue structure of the NTT
Group over time, as illustrated in The NTT Group: 30
Years of History, indicate that voice systems accounted for about 48% of revenue in 2008. In contrast, that
proportion had fallen to 21% by 2015, and systemintegration-related revenue (including softwaredevelopment) increased from 26% of the total to 46%[1]. The percentage of solutions-related revenue has
also increased in recent years, and the work to develop the software to support those systems has come toplay a more significant role.
Consequently, by improving the productivity ofsoftware development and stably providing highquality software in a short time period, we will beable to expand services while reducing the total costof ownership (TCO) and targeting further growth.
At the NTT Software Innovation Center (SIC, hereafter), we have developed Macchinetta as a framework for improving the efficiency of software development. As a result, by improving the productivity ofsoftware development as well as eliminating redundant investments and utilizing the created technology
in a common manner, we aim to reduce TCO acrossthe NTT Group as a whole.
The Feature Articles in this issue describe our
1efforts to improve the productivity of software development using the Macchinetta framework [2, 3, 4].
2. Macchinetta
Macchinetta is an application framework targeting
enterprise applications. Prescribing the framework ofsoftware makes it possible to improve productivity,
stabilize quality, and in turn, reduce TCO. In otherwords, Macchinetta is a software bundle composed ofopen source software that is used on a global scale,and it consolidates the methods of utilizing eachpiece of software in that bundle.
In Machinetta, we have collected developmental
technology and know-how and consolidated maintenance and support systems in a common framework.
Thus, Macchinetta improves the efficiency of software development, stabilizes operations (including
handling security weaknesses), and reduces TCO(Fig. 1).
Macchinetta is presently being applied to softwaredevelopment throughout NTT Group companies. In
fact, almost all new software development projects
are utilizing Macchinetta. From now onwards, wewill not only apply Macchinetta to new projects but
will sequentially apply it to existing systems while
also upgrading those systems, with the objective of
NTT Technical Review

Feature Articles

Improve efficiency of software development,
stabilize operations, and reduce TCO.

Develop software
efficiently by using
unifiedimplementation
method.

Reduce costs byapplying tools.

Improveproductivity ofsoftwaredevelopment byeducatingengineers.

Solve problems
and strengthen
security by
applying
maintenancesupport system.

Application
Macchinetta
Framework
Hardware/operating system/middleware

Fig. 1. Benefits of Macchinetta.

reducing TCO across the entire NTT Group.
3. Efforts to improve productivity
To improve the efficiency and stability of softwaredevelopment by applying Macchinetta, it is essential
to cultivate human resources with the skills andknow-how needed to master Macchinetta. At the SIC,
we are preparing study materials by utilizing our
experience in developing human resources, and weare striving to nurture experts on Macchinetta acrossthe entire NTT Group and to establish a pool of
Macchinetta-related human resources. Furthermore,
we will further improve the productivity of softwaredevelopment by establishing tools for supporting
software development using Macchinetta and by promoting automation and labor-saving practices. In
particular, we hope to improve the efficiency of test
processes that significantly affect quality and productivity while advancing research and development(R&D) focused on automation, regardless of the presence or absence of Macchinetta.
4. Efforts to further improve efficiency
The increasingly severe and fluctuating market
conditions in recent years mean that it has becomeVol. 15 No. 2 Feb. 2017

necessary to develop services at an ever faster rate.
However, at many major companies, so-calledsiloization* is continuing, partial optimization has
become acceptable, and it is becoming impossible toprovide timely and responsive services. In response
to such circumstances, we are setting up service
development teams that span the business department(Biz) such as the planning and sales department, thedevelopment department (Dev), and the operations
department (Ops), as well as hammering out services
with a sense of urgency and proposing development
methods (BizDevOps) that will ensure flexible
growth. To ensure cooperation between related
departments based on a development style that is bothlean and agile, it is essential to ensure smooth communications between those departments. We also
propose using data models in order to obtain goodcommunication between departments with differing
cultures and complex systems.
5. Future direction
The SIC plans to continue the initiatives describedin this article while maintaining acute awareness of*

Siloization: Developing a silo mentality in which people do notshare information with other departments.

2

Feature Articles

the status of software development across the NTT
Group. Moreover, we will continuously promote
R&D aimed at improving the productivity of software development across the NTT Group in a waythat will reduce TCO and expand our businesses.
References[1][2]

The NTT Group: Thirty Years of History, 2015.
G. Suzuki, A. Kanamaru, T. Iwatsuka, J. Katada, S. Okada, S. Mochida, K. Natsukawa, K. Motohashi, T. Hishiki, T. Kaneko, K. Tanabe, H.
Izumoto, M. Sakai, K. Yamashita, and Y. Iwaki, “Improving the Effi-

[3]

[4]

ciency of Application Development Based on the Macchinetta Framework,” NTT Technical Review, Vol. 15, No. 2, 2017.
https://www.ntt-review.jp/archive/ntttechnical.php?contents=
ntr201702fa2.html
H. Tanno, M. Oinuma, and K. Natsukawa, “Test Automation Technology to Promote Early and Frequent Releases of Software at Low
Cost,” NTT Technical Review, Vol. 15, No. 2, 2017.
https://www.ntt-review.jp/archive/ntttechnical.php?contents=
ntr201702fa3.html
S. Aihara, M. Inoue, A. Jin, Y. Furukawa, T. Tanaka, N. Sekiguchi, E.
Oka, and K. Horikawa, “A Quick Software Development Method for
Improving Competitiveness of Services,” NTT Technical Review, Vol.
15, No. 2, 2017.
https://www.ntt-review.jp/archive/ntttechnical.php?contents=
ntr201702fa4.html

Hikaru Suzuki

Vice President, Head of NTT Software Innovation Center.
He received a B.E. and M.E. from Waseda
University, Tokyo, in 1986 and 1988. Since joining NTT in 1988, he has contributed to thedevelopment of the operation and business support systems for various telecommunication services such as PHS (personal handy-phone system), 3G-mobile, Free-Phone, and Next Generation Network. He is involved in developing andmaintaining cloud services and software-defined
networking services by using open source software such as OpenStack, CloudFoundry, Ryu/
GoBGP, and Docker. He was the chair of theTechnical Committee on Information Networksof IEICE (Institute of Electronics, Information
and Communication Engineers) from May 2010
to May 2012. He is a member of IEEE (Instituteof Electrical and Electronics Engineers).

3

NTT Technical Review

Feature Articles: Improving Productivity in Software
Development Using Macchinetta Framework

Improving the Efficiency ofApplication Development Based on
the Macchinetta Framework
Gengo Suzuki, Akira Kanamaru, Takuya Iwatsuka,
Junya Katada, Satoshi Okada, Seiichiro Mochida,
Katsuyuki Natsukawa, Kenji Motohashi,
Takanori Hishiki, Takehiko Kaneko, Kenji Tanabe,
Hiroshi Izumoto, Miyotaka Sakai, Katsuyuki Yamashita,
and Yosuke Iwaki
Abstract

At the NTT Software Innovation Center, we are working to improve the stability and productivity ofsoftware development throughout the entire NTT Group by conducting research and development on
new software development techniques and making these techniques accessible to developers. This article
introduces our work on the Macchinetta framework that we developed in order to produce web-based
enterprise applications more efficiently on the Macchinetta tool suite that commonizes development
tools, and on the Macchinetta talent pool that provides talented developers to support efficient development.
Keywords: software development, application framework, OSS

1. Introduction
The NTT Group develops software on a very large
scale in order to create a diverse range of enterpriseapplications (enterprise APs) and systems for the
management of information about our networks andcustomers. Increasing the efficiency of this development work is therefore a very important issue. Verylittle of our software has been developed entirely
from scratch or entirely by manual effort in recent
years. Development companies and individual developers strive to improve their productivity by making
use of frameworks geared towards efficient softwaredevelopment and development tools that allow software to be designed, produced, and tested more efficiently through the use of automation.
1

However, if individual developers use different
frameworks and development tools, they will develop
enterprise APs in different ways with different operating methods. This is problematic because developers have to spend a lot of time familiarizing themselves with frameworks, porting systems to newframeworks, and getting disparate frameworks tocooperate with one another. Even if systems aredeveloped using the same framework, operational
problems can still arise if the systems use different
versions of the framework. Because the NTT Groupdevelops software on a large scale, there are also
cases where each company has developed its own setof tools. The inability to share these tools and knowhow is a problem with regard to improving productivity.
NTT Technical Review

Feature Articles

Macchinetta tool suite(development tools)
Designsupporttools

Test
automation
tools

Codingautomation
tools

Macchinetta talent pool
(Macchinetta certified developers)

Provide tools to makedevelopment more efficient.

Hardware / OS / middleware

Provideinfrastructure.

Macchinetta
framework

Requirements
definition

DesignCodingTestingAPdevelopment

Provide humanresources.

Application

Skill level
Educational
materials

High
Lv.3
Lv.2
Lv.1

Low
Acquire development skills
through training based onUseacertification
educational materials.
system to visualize
skill levels.

Development projects using Macchinetta

Fig. 1. Efforts to improve the efficiency of application.

To solve these issues, we have developed an application framework to support the development ofenterprise APs at NTT Software Innovation Center.
Furthermore, to maximize the efficiency of application development based on this framework, we aim topromote the use of a common set of development
tools and to cultivate developers who are all skilled in
the use of the framework and the tools.
2. Setting up an enterprise AP framework: theMacchinetta framework
When developing enterprise APs, it is becoming
common practice to use a software infrastructure
called an application framework (AP framework). An
AP framework consists of a software framework usedby software developers to implement the standard
structure of an application using a software development environment consisting of elements such as an
operating system, programming language, and middleware. The shared functions of an AP framework
make it possible to improve the productivity of software development. Also, by developing systems
according to established routines that reduce the differences between individual developers, it is possible
to achieve uniform quality. Furthermore, the cultivation of developers who are all experienced with thisframework facilitates their understanding of thesesystems so they can maintain them more efficiently.
However, the following issues have arisen whenusing an AP framework. First, in order to reap theVol. 15 No. 2 Feb. 2017

abovementioned benefits, developers had to learn theestablished routines for using the AP framework, andhad to become familiar with diverse know-how in
actual development. In addition, it was necessary tochoose from a wide variety of existing frameworks.
In particular, even in the NTT Group, there was an
issue in that the expansion of similar AP frameworks
resulted in duplication of technical development andmaintenance costs incurred by each company.
To resolve these issues, reduce the initial training
costs, and avoid duplicated maintenance costs, theNTT Software Innovation Center has developed theMacchinetta framework as a new AP framework thatcan be used in common throughout the NTT Group[1] (Fig. 1). The Macchinetta framework uses globally standard open source software (OSS) as a basic
principle, and it can be applied to a wide range of different information systems without being tied toproprietary technologies. The Macchinetta framework consists of an OSS stack recommendation
model as a common feature that has been verified tobe capable of being used stably in multiple APs, andtechnical documentation to facilitate the smooth
implementation of development using the AP framework (Fig. 2). By expanding the scope to incorporate
online processing, batch processing, client development, and the like, we can use the framework forenterprise APs in a wide range of fields.
The Macchinetta framework has been supplied by
the NTT Software Innovation Center to NTT Group
companies that carry out system development and has
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Feature Articles

Framework takes care of details that
do not have to be considered or
implemented.

Application

Minimize the parts thatdevelopers have toimplement.

Macchinetta
framework[Uniform quality]
Differences between developers are reduced bydeveloping according to established routines ofthe framework.

Hardware / OS / middleware
Macchinetta framework materials[Maintenance efficiency]
Understanding of the system is facilitated byshared knowledge of the framework.

[Improved productivity]
Development workload is reduced by providing
various common functions.

OSS stack recommended model(combining multiple OSS packages)• As a common feature of enterprise
AP frameworks, a verified stack thatcan be used stably in multiple APs• Specifically, implementing selection
and verification from multiple OSS
packages

Technical documentation• Application technology that uses
an enterprise AP framework toensure smooth implementation ofwork by teams, from design throughcoding and testing• Specifically, work procedures, rules,
sample APs, etc.

Fig. 2. Overview of Macchinetta framework.

already demonstrated its worth in over 100 projects.
In particular, we are not only actively introducing thistechnology in projects at NTT DATA and NTT COMWARE but are also feeding back knowledge andknow-how from these projects in order to promote
close cooperative relationships. NTT DATA is
deploying the Macchinetta framework with libraries
needed for business as the TERASOLUNA Server
Framework for Java (5.x) and is applying this framework to large-scale software development in many
enterprise systems, which is a major achievement.
Also, at NTT COMWARE, we are gaining a lot ofexperience with applications centered on projects for
the NTT Group.
3. Commonization of development tools: theMacchinetta tool suite
In modern software development, various development tools are generally used to improve work efficiency and automate as much of the work as possible
in the design, coding, and testing processes. Thesedevelopment tools are often developed separately at
various companies, resulting in problems such as
duplicated functions and compatibility issues. Even if
commercially available technology is used, different
companies may use different technologies, resulting
in larger training costs for the NTT Group as a whole.
3

We have therefore been working to organize andselect suitable development tools to eliminate redundant development efforts and prevent the dispersionof know-how. This selected set of development tools
is called the Macchinetta tool suite.
In developing the Macchinetta tool suite, we
assessed the effectiveness of commercial tools andexisting tools and compiled a list of the development
tools that should be adopted. We also compared thefunctions of these development tools in detail andchecked them for duplicated functions. On this basis,
we set up the Macchinetta tool suite by deciding
whether or not to adopt these tools and continue with
their development. An overview of the types of development tools included in Macchinetta and each tool’srole in the software development process are presented in Table 1. In this way, we were able to prepare development tools to support every step fromdesign to coding and testing, and to make these tools
available throughout the NTT Group.
These development tools make it possible toachieve benefits such as improved productivity over abroad range of products, although the characteristics
and/or conditions of the products to which they areapplied mean that it may not be possible to achieve
the desired effect. Therefore, while anticipating
advances in development techniques, we will also
continue to examine, integrate and develop tools,
NTT Technical Review

Feature Articles

Table 1. The Macchinetta tool suite (partial list).
Tool

Target process

Overview of tool

UI design support tool

DesignIntegrated development environment that automatically
produces source code, settings files, and design
documents from UI design information

Automatic code generation tool

Design - coding

Automatic generation of source code from business logic
design information

Unit test code generation support tool

Unit testing

Automatic generation of unit test code and test data forsource code

Integration test case generation support tool Integration/system testing

Automatic generation of integration test case list

Continuous integration support tool

Unit - integration/system testing

Automation of repeated build/testing/deploy cycles,
support for continuous integration

Source code diagnostic tool

Coding - unit testing

Discovery of memory leaks and other inherent issues insource code

Test execution automation tool

Integration/system testing

Automation of test execution involving the use of UIs

DB access code creation support tool

CodingInput support for generation of DB access codes

DB: database
UI: user interface

collect and share know-how on the use of these tools
among NTT Group companies, and provide feedback
through the development of tools that make the greatest possible use of this know-how.
4. Development of human resources to make useof common techniques: the Macchinetta
talent pool
The use of a common set of techniques has major
benefits in terms of ensuring the availability ofhuman resources. Before these techniques can beused in common, however, it is necessary to havespecific technical personnel allocated to each technique. This can make it difficult to ensure that technical personnel are available during busy seasons,resulting in higher development costs, and can also
result in development companies becoming
entrenched in the use of particular techniques. However, if common development techniques such as
frameworks and tools are provided as an infrastructure as described above, then it should be possible toreduce the cost of technical education and make iteven easier to secure the necessary human resources.
The environment for the education of talented individuals with this common set of skills is called theMacchinetta talent pool. We are working to support
the cultivation of this sort of talent pool.
As a part of this initiative, we are working to prepare educational materials relating to these common
techniques. An effective way of cultivating high quality developers is to provide them with hands-on
Vol. 15 No. 2 Feb. 2017

access to the frameworks and other technologies inorder to learn by building things. However, developers currently have to learn by extracting the required
information from large amounts of information suchas ordinary commercial primers and web pages,
which is a time-consuming and inefficient process.
Also, the number of developers assigned to a single
development project may run into the hundreds, andtraining them is no easy task. Therefore, to solve thisproblem and improve the efficiency of our humanresources, we prepared educational materials for the
Macchinetta framework.
The Macchinetta educational materials are targeted
at beginners with just a basic understanding of Javaand are constructed in order to provide a combinationof basic instruction and hands-on experience with
programming exercises. These materials pick out
commonly used functions and arrange them for
maximum educational benefit in order to provide aplain description of the recommended implementation methods and rules, thereby facilitating rapid
learning. By preparing a hand-made selection of
exercises and solutions, we made it possible to gain
practical knowledge through simulated development
experience. This made it easy to train the humanresources needed for Macchinetta (Fig. 3). These
educational materials are made available to every
company in the NTT Group and are used as educational programs for companies involved with development projects using the Macchinetta framework,
thereby contributing to a large increase in the efficiency of education.
4

Feature Articles

Description of exercises

Training

Macchinetta human resources

Q

Basic knowledge
instruction

Educational
materials for
Macchinetta
framework

Tackling exercise
problems(programming
experience)

Answers to exercises

Beginner level(basic knowledge of Java)
Next itemA

Fig. 3. Educational materials for Macchinetta framework.

5. Future prospects
The environment surrounding software development is evolving every day. By taking advantage ofthe system infrastructure offered by cloud services, it
is becoming unnecessary these days for developers tobuild their own system infrastructure. However, it isnecessary to adapt to a wide variety of client environments with diverse user environments, terminals,
operating systems, and browsers. Furthermore, it isexpected that application technology will be developed for technical areas with a higher level of difficulty than system development. We therefore aim tocontinue with research and development (R&D)
aimed at expanding the applicable range and operating environment of frameworks and tool suites inorder to achieve higher productivity. Also, by modifying these environments, we will further elevate theirimportance and the opportunities for porting systems
to new frameworks and environments. We believethat it will become important to prepare procedures
and tools for improving the productivity of migration.
The Macchinetta infrastructure consists of various

5

OSS packages, but in order to provide higher-quality
support and improve the reliability of its frameworks
and tools, we are actively contributing to the improvement of these OSS packages. In addition to improving quality by providing patches to fix bugs, we arealso conducting R&D together with the OSS community to provide new functionality. In particular, weplan to work together with the other NTT Group companies to actively contribute to Spring [2], which is an
essential part of the OSS framework.
To cultivate human resources, we are investigating
the preparation and operation of a Macchinetta developer certification system. This certification system
will make it possible to clearly visualize developers
and their skill levels, thereby facilitating the marshalling of human resources.
References[1][2]“Development of an OSS Enterprise AP Framework Aimed at
Improving Software Development Efficiency and Productivity,” Business Communication, Vol. 51, No. 9, pp. 4–7, 2014 (in Japanese).
NTT DATA Corporation, “Spring Primer: Developing Java Applications in the Spring Framework,” Shoeisha, 2016 (in Japanese).

NTT Technical Review

Feature Articles

Gengo Suzuki

Seiichiro Mochida

Senior Research Engineer, Software Engineering Project, NTT Software Innovation Center.
He received a B.S. and M.S. in mathematics
from Tohoku University, Miyagi, in 1988 and1990, and a Ph.D. in computer science from the
University of Electro-Communications, Tokyo,
in 2013. He joined NTT in 1990. His researchinterests include database design, multi-databasesystems, graph data management, and software
engineering. He is a member of the Information
Processing Society of Japan and the Institute ofElectronics, Information and Communication
Engineers.

Senior Research Engineer, Software Engineering Project, NTT Software Innovation Center.
He received a B.E. in science and engineeringfrom Waseda University, Tokyo, in 2002 and an
M.E. in engineering science from the Universityof Tokyo in 2004. He joined NTT in 2004. Hisinterests include software engineering.

Akira Kanamaru

Katsuyuki Natsukawa

Senior Research Engineer, Supervisor, Software Engineering Project, NTT Software Innovation Center.
He received his B.E., M.E., and Ph.D. fromTohoku University, Miyagi, in 1996, 1998, and2001. He joined NTT in 2001. His research interests include computer networks and software
engineering.

Senior Research Engineer, Supervisor, Software Engineering Project, NTT Software Innovation Center.
He received an M.E. from Nara Institute of
Science and Technology in 1996. He joined NTT
in 1996. His current research interests include
software engineering.

Takuya Iwatsuka

Kenji Motohashi

Researcher, Software Engineering Project,
NTT Software Innovation Center.
He received a B.E. and M.E. in computer science from Nagoya University, Aichi, in 2011 and2013. He joined NTT in 2013. His research interests include programming language theory, program verification, and software engineering.

Junya Katada

Researcher, Software Engineering Project,
NTT Software Innovation Center.
He received a B.E. and M.E. in computer science from Tokyo Institute of Technology in 2003
and 2005. He joined NTT COMWARE in 2005.
He moved to NTT in 2016. His interests include
software engineering.

Satoshi Okada

Senior Research Engineer, Software Engineering Project, NTT Software Innovation Center.
He received a B.E. and M.E. from Toyohashi
University of Technology, Aichi, in 1993 and1995. His current research interests include software engineering.

Vol. 15 No. 2 Feb. 2017Manager, System Engineering Headquarters,
NTT DATA Corporation.
He received a B.E. in computer science and an
M.E. in communications and integrated systems
from Tokyo Institute of Technology in 2003 and2005. He joined NTT DATA in 2005. He is
engaged in developing thin client systems, cloudcomputing systems, and application frameworks.

Takanori Hishiki

Manager, System Engineering Headquarters,
NTT DATA Corporation.
He received a B.E. in computer science and an
M.E. in communications and integrated systems
from Tokyo Institute of Technology in 2003 and2005. He joined NTT DATA in 2005. He is
involved in developing thin client systems, cloudcomputing systems, and application frameworks.

Takehiko Kaneko

Research Manager, Center for Applied Software Engineering, Production Engineering
Department, System Engineering Headquarters,
NTT DATA Corporation.
He received an M.E. in industrial engineeringfrom Aoyama Gakuin University, Tokyo, in
1997. He joined the Public System Division of
NTT DATA in 1997 and developed a large-scaletrading system. He was also involved in developing automated tools. He is currently in charge of
R&D and deployment of automated tools including the TERASOLUNA Suite.

6

Feature Articles

Kenji Tanabe

Katsuyuki Yamashita

Manager, System Engineering Headquarters,
NTT DATA Corporation.
He received a B.E. in electrical engineeringfrom Gunma University in 1988. He joined NTT
DATA in 1989. His current work involves technical strategies and public relations in the field ofsoftware engineering.

Manager, SE Department in Core Technology
Quality Management and Engineering Division,
NTT COMWARE CORPORATION.
He received a B.E. and M.E. in communicationengineering from Osaka University in 1997 and1999. He joined NTT COMWARE in 1999. His
main interest is improving the efficiency of software development.

Hiroshi Izumoto

Yosuke Iwaki

Manager, System Engineering Headquarters,
NTT DATA Corporation.
He received a B.E. and M.E. in informationengineering from Hiroshima University in 1986
and 1988. He joined NTT DATA in 1989. He iscurrently engaged in developing technical strategies and working in public relations in the fieldof software engineering.

Manager, SE Department in Core Technology
Quality Management and Engineering Division,
NTT COMWARE CORPORATION.
He joined NTT in 1990. He has contributed tothe development of the software development
environment. His main interest lies in the engineering of software development tools.

Miyotaka Sakai

Manager, SE Department in Core Technology
Quality Management and Engineering Division,
NTT COMWARE CORPORATION.
He joined NTT in 1985. His main interest is
studying best practices for software development
projects in order to improve software development methods.

7

NTT Technical Review

Feature Articles: Improving Productivity in Software
Development Using Macchinetta Framework

Test Automation Technology toPromote Early and Frequent Releasesof Software at Low Cost
Haruto Tanno, Morihide Oinuma,
and Katsuyuki Natsukawa
Abstract

There is growing demand to speed up the software release cycle while holding down costs in order torapidly deploy services that meet the changing needs of end users. Considerable interest has been
focused on technology for software testing, which accounts for a large share of total development costs,
to ensure a certain level of software quality. In this article, we introduce some concrete measures at NTT
for supporting test design and verification of test results in software testing.
Keywords: software testing, test design, verification of test results

1. Introduction
Software development is divided into processes, as
illustrated in Fig. 1. Software errors not detected in
the testing phase go out to end users in the release, so
testing is clearly very important to ensure the qualityof the software. As long as testing is done manually,
however, it will be extremely costly. User needs andsoftware/hardware development of the operating
environment have been evolving at an ever more
rapid pace in recent years, and this requires early andfrequent releases of new or revised software to meetthese needs (Fig. 2). To maintain quality throughrepeated software release cycles, regression testing
must be done to make sure new portions of software—including portions implementing new functions and new operating environments—do not havean adverse effect on existing software capabilities,
and this testing of legacy capabilities whenever software is released is also extremely costly.
In order to pursue software development that constantly improves upon quality, cost, and delivery(QCD), the NTT Software Innovation Center isresearching and developing technology that contributes to a set of test automation tools as part of the1

Requirements
definition

DesignCodingTesting

Fig. 1. Software development process.

Development

Release

Improve

Employedby users

Analysis
Collect user
feedback.

Fig. 2. Feedback loop.

NTT Technical Review

Feature Articles

Test management

Test
planning
Test design

Test execution(Existing automation
tools are available.)

Verification oftest results

TestreportingFig. 3. Testing procedure.

Macchinetta tool suite [1]. The idea is to promote test
automation that performs tasks by machine that werepreviously done manually.
2. Current state of software testing support
The objectives of software testing are to verify thatsoftware has been implemented according to thedesign and specifications, and to reduce the numberof defects. The testing process mainly consists of fivetasks: test planning, test design, test execution, test
reporting, and test management (Fig. 3). In test planning, issues such as the time frame and allocation of
resources for testing are decided based on the overall
development plan. Test design involves clarifying thevarious tests that must be done, designing test cases
comprehensively, refining specific test feasibility
procedures for each test case, and creating scripts forautomatic execution. In test execution, test data are
input for each of the test cases, the software is run,and test results revealing how the software behavesfor each of the test cases are recorded. These results
are then referenced against verified test results toensure the software behaves according to design. In
test management, management of the state of test
execution is carried out as needed, and the test plan isrevised if necessary. When all tests have been executed, the results are summarized in test reporting, andthe process is complete.
Three of these test processes are especially important tasks: test design, test execution, and verificationof test results. Once test cases are produced in the test
design, the tests must be implemented precisely withno missing test cases so they can be repeatedly used
not only as new tests but also as regression tests incases where software is patched or improved. Test
execution and verification of test results must be carried out repeatedly against all legacy functions when
Vol. 15 No. 2 Feb. 2017

dealing with software enhancements and new operating environments, and the burden increases exponentially as the scale of software increases. Therefore,
these three tasks are areas in which the effects ofautomation are significant for maintaining software
quality, cutting costs, and implementing early andfrequent releases.
Considerable progress has been made in automating unit testing used to verify the functional operationof small individual units making up software, but
automation has made little headway in dealing withintegration testing of larger software programs combining multiple modules that include user interface(UI) screens or in dealing with system testing to catch
system-level errors.
A number of tools have become generally available
in the development workplace for automating integration testing and system testing. One example isSeleniumWebDriver, which automatically executes a
web application test based on a prepared test script.
However, we note that currently, test design and verification of test results still involve a considerable
amount of manual labor. While tools supporting thetest design of some functional testing are available,
there are major barriers to introducing these tools inthe development workplace. Obstacles include theneed for testing staff to have specialized knowledgeof the tools and the testing technique that the tools
use, and the need to write descriptions in an unfamiliar language. In addition, verification of test results
requires a great deal of visual inspection by technicians to ensure screens are displayed correctly and soon, and manually checking a large number of test trials one by one is extremely costly.
3. Research vision
With the goal of improving the QCD of test processes,
2

Feature Articles

Test design, test implementation
Input

OutputMaterials at
development site

http://www.ntt.co.jp/

Login ID
Password
SearchNTTtechnology

N

Click!
Click!
Click!

Test data

Automatic test
resultsverification
technology

Automatic test
execution tool

Test case list
Test script

Test process artifacts

Test result materials at
development site(including automatically
executed results)

Existing
technologies

Test results

NTT
technology

Item
1
2
…

Design documents,
source code,
repository,
executable files,
etc.

…

Test design
automation
technology

Procedure…
…
…
…

OutputInput

Search Screen

Test design, test
implementation artifacts

Item
1
2

Test results verification

Test execution

N

Content Pass/fail
…
…
…
…
…

Test results report

Fig. 4. Research vision.

our vision is to automate all testing during and after
integration testing from test design to verification oftest results, as shown in Fig. 4. We highlight the following two noteworthy features of this approach:(1)	Automating test design using design documents, source code, executable files and othermaterials available at the development worksite means that everything needed for the test
execution—test case list, test data, and execution script files—is automatically generated.
This effectively generates tests without errors
or omissions at relatively modest cost.
(2)	Any problem or error in the test execution
results for each test case (application screenshots, etc.) is automatically detected. This
markedly reduces the amount of visual verification work, prevents omissions from occurring, and thus improves the quality of applications.
In the following sections, we introduce two tools
for automating the test design and verification of test
results: the integration testing design support tool
TesMa and the UI layout test support tool ULTDiff.
We discuss these tools in the context of an enterpriseapplication featuring a front-end web application
developed using the Macchinetta framework.
4. Integration testing design support
tool: TesMa
In order for end users to input data in a field on a
web application screen, we must ensure that the software behaves as designed no matter what data areentered in the field. For example, if the correct input
in the field must be a 10-digit number, the test design
3must test for correct entries such as “0123456789”
but also test for the full range of potential incorrect
entries: “012345678a” (violates the numericalrequirement), “01234567890” (violates the numberof digits requirement), and “01234567890a” (violates
both the numerical and number of digits requirements). It is challenging to implement such a test
design without errors or omissions even with highly
skilled technicians, and the cost can be excessive.
To resolve this issue, we developed the integration
testing design support tool called TesMa [2] that
automatically generates test cases and test data needed for integration testing enterprise applications fromthe software design documents (Fig. 5). The latest
version of TesMa goes beyond generating test cases
and test data to automatically generate execution
scripts to automatically run the test cases and test
data. TesMa has the following features:(1)	The input for the tools is a set of design documents written according to set descriptive
rules. These documents are the results of thedesign process, which is part of the existingdevelopment process. It thus has the advantage of being easy to introduce into the development workplace.
(2)	The tool generates a comprehensive set of test
cases, test data [3], and executable script files[4] based on processing patterns and input
data variations. This helps to prevent omissions from occurring in manually created test
designs and also generates the test datarequired to execute each test case, making test
execution much easier.
These features of the test tool reduce the cost of
integration testing, while maintaining software quality
NTT Technical Review

Feature Articles

OutputInput
Software design
documents

Test case list
Item
1
2
…

Integration
testing design
support tool
TesMa

N

Test data

Procedure…
…
…
…

Execution
script files

For example:

Screen design
document

Process flow diagram

Fig. 5. Integration testing design support tool.

Exhaustively detect differences
between correct screen andscreens under test.

Reference device(correct screens)

Visualization of errors
Omissions

Input

Test device(comparison screens)

UI layout
testing
support tool
ULTDiff

Output Changes

Input

OutputResults

Developer

Omissions

Summaryreport ofresults

Errors are highlighted on screen so they
can be visualized and not overlooked.
Input is a screenshot of the app
screen; no other input is required.

Fig. 6. UI layout test support tool.

through a comprehensive test design.
5. UI layout testing support tool: ULTDiff
Web application testing is done to ensure screenson various types of client devices—smartphones,
tablets, and personal computers—display correctlyfor operating systems (OSs), browsers, and otherapplications. The test results must also be verified.
For example, one might find that screens are displayed correctly on some devices, but buttons haveVol. 15 No. 2 Feb. 2017

been pushed off screen on other devices. There is anenormous range of terminals available, new model
smartphones are constantly being introduced, andOSs are frequently updated. This makes it extremely
cumbersome and time-consuming to visually inspect
each and every application screen for errors whenverifying test results.
The ULTDiff tool addresses these problems, as
shown in Fig. 6, by automatically detecting missing
or displaced screen elements such as buttons. This not
only greatly reduces the amount of work required to4

Feature Articles

visually check for errors across the enormous range
and variety of application screens but also catches
errors that might otherwise be overlooked, and it
improves the quality of applications. The ULTDiff
tool has the following features:(1)	ULTDiff reduces the cost of manual detection
and prevents omissions by exhaustively
detecting the differences between a correct
screen and screens under test.
(2)	It assists people to effectively decide whether
or not each detected difference is an error byhighlighting differences on a screen.
(3)	It can be applied to many kinds of applications
and can be easily introduced to the development process because it only needs screen
images as input and does not depend on specific implementation technology.
The combination of these features greatly reduces
the amount of work involved in detecting errors andomissions when testing applications under development on a diverse range of client devices and when
testing recently released applications on new model
devices. Moreover, when revising or adding new
functions to applications, ULTDiff can be used for
regression testing to make sure the older programming still works with the new changes. ULTDiff significantly reduces the man-hours associated witheach release and thus makes it possible to implement
rapid release cycles.

tain excellent quality through comprehensive test
design while cutting costs is becoming apparent at
NTT development worksites. Meanwhile, ULTDiff
has been made available to several NTT Group companies, and we continue to refine the tool based on
feedback from the development sites, with plans for ageneral deployment in the near future.
In the future, we will be less reliant on massive
design manuals supporting the waterfall development
approach and will move toward test design support
based on existing resources such as source code for awide range of development processes. Without
depending on a specific development process, we
remain actively involved in research and development that helps all of the development worksites.
Building on the QCD gains made so far, we are committed to steadily advancing software research anddevelopment in the years ahead.
References
[1]

[2]

6. Future development[3]

TesMa technology has already been adopted in over
100 software projects by NTT Group companies
domestic and foreign, and the tool’s ability to main-[4]

5

G. Suzuki, A. Kanamaru, T. Iwatsuka, J. Katada, S. Okada, S. Mochida, K. Natsukawa, K. Motohashi, T. Hishiki, T. Kaneko, K. Tanabe, H.
Izumoto, M. Sakai, K. Yamashita, and Y. Iwaki, “Improving the Efficiency of Application Development Based on the Macchinetta Framework,” NTT Technical Review, Vol. 15, No. 2, 2017.
https://www.ntt-review.jp/archive/ntttechnical.php?contents=
ntr201702fa2.html
H. Tanno, X. Zhang, K. Tabata, M. Oinuma, and K. Suguri, “Test
Automation Technology to Reduce Development Costs and Maintain
Software Quality,” NTT Technical Review, Vol. 12, No. 1, 2014.
https://www.ntt-review.jp/archive/ntttechnical.php?contents=
ntr201401fa3.html
H. Tanno and X. Zhang “Automatic Test Data Generation Based on
Domain Testing,” IPSJ SIG Notes, 2014-SE-186, No. 6, pp. 1–8,
2014.
H. Tanno and X. Zhang “Test Script Generation Based on Software
Design Documents,” IEICE Technical Report, Vol. 115, No. 154, pp.
103–110, 2015.

NTT Technical Review

Feature Articles

Haruto Tanno

Researcher, Software Engineering Project,
NTT Software Innovation Center.
He received a B.E. and M.E. in computer science from The University of Electro-Communications, Tokyo, in 2007 and 2009. He joined NTT
in 2009. His interests include programming languages and software testing. He received theSuper Creator Award from the Information-technology Promotion Agency in 2008, paper awards
from the Information Processing Society ofJapan (IPSJ) in 2009, 2013, and 2016, and thePresident’s Award from NTT in 2016. He is amember of IPSJ.

Katsuyuki Natsukawa

Senior Research Engineer, Supervisor, Software Engineering Project, NTT Software Innovation Center.
He received an M.E. from Nara Institute of
Science and Technology in 1996. He joined NTT
in 1996. His current research interests include
software engineering.

Morihide Oinuma

Senior Research Engineer, Software Engineering Project, NTT Software Innovation Center.
He received a B.E. and M.E. in electrical engineering from Keio University, Kanagawa, in1984 and 1986. He joined NTT in 1986. His current research interests include software engineering. He is a member of IPSJ.

Vol. 15 No. 2 Feb. 20176

Feature Articles: Improving Productivity in Software
Development Using Macchinetta Framework

A Quick Software Development
Method for Improving
Competitiveness of Services
Satoru Aihara, Masayuki Inoue, Akio Jin,
Yoshinori Furukawa, Takako Tanaka, Nagisa Sekiguchi,
Eiichi Oka, and Keitaro Horikawa
Abstract

Environmental changes surrounding our society are becoming more uncertain, and therefore, thedevelopment of services must be more flexible than ever. To adapt to such an environment while con­tinuously receiving feedback from the market and our customers, we urgently need to switch to iterativeand incremental software development. This article presents an analysis of problems concerning
responses to changes in the environment, with a focus on devising effective methods for developing
software. First, as an alternative to conventional software development methods, we introduce BizDev­
Ops—an approach that enables rapid development through unified teams. Then we introduce a frame­
work as an alternative to re-engineering, which takes several years. Specifically, we explain a re-engi­
neering model in which multiple One Team groups simultaneously develop software in an iterative andincremental manner by working together with other teams while each team shares the same concept
model.
Keywords: lean and agile, BizDevOps, early-phase analysis

1. Introduction: BizDevOps
We discuss in this section the concept of BizDev­
Ops and describe ongoing efforts related to its devel­
opment.
1.1 Competitiveness, speed, and company culture
Globalization and technological innovations haveresulted in an environment surrounding business mar­kets that is intensifying in terms of competition to
rapidly get products to market (speed of productdevelopment). Innovative companies are shortening
the time taken to develop services, whereas compa­
nies applying entrenched conventional development
methods are finding it difficult to release products inan agile manner. For example, the conventional
approach typically takes one year to develop new
1

services to full specification and release them with
top quality. By the time a product is released, themarket may no longer need that product, and as aresult, the risk of not getting timely feedback increas­es (Fig. 1).
In the vicious circle of being unable to sell products
even if they are made, there is a danger that employ­
ees will lose motivation, strains will be put on theorganization, and competitiveness will rapidly dete­riorate. At present, many system integrators and busi­
nesses that develop their own in-house systems use
the conventional waterfall approach to development,
in which progress flows steadily downward throughthe different development phases. Although develop­
ers are frequently aware that they should adopt a
faster way of doing things, it is not easy to do so while
expecting to earn profits in the conventional way
NTT Technical Review

Feature Articles

Products released to the market
and customers:
Products with ideal functions andtop quality sent out once a year

4

5

6

7

8

9

10

11

12

1

2

Status of utilization of functions
by customers:• Only 20% of all functions are used.
• New ways to use functions andspecification changes are generated.
• Gradually, functions become unused.

3

Number of productfunctionsFeedback from the market and customers:• Feedback is first obtained after product completion:late product release = late feedback• Risk of losing the opportunity to sell the product due
to changing circumstances and product obsolescence:
lost opportunities

Gap

Time

Fig. 1. Traditional service development and utilization status.

because the current situation does not alert them to asense of impending danger. The track records of suc­cessful organizations, and their rules, culture, andcustoms have actually become factors that obstruct
new efforts, and innovative changes are fraught withtremendous problems.
1.2 N ecessity of One Teams sharing their thinking
in a lean and agile way
The concept called BizDevOps was proposed as ameans of responding to changes in the business mar­ket. The objective of BizDevOps is to foster coopera­tion among business departments (Biz) such as theplanning and sales departments, development depart­ments (Dev), and operations departments (Ops) inorder to produce superior services that can adapt rap­
idly to change. We have formed an approach called
One Team, which refers to a unified team sharing acommon aim to overcome institutional hurdles suchas that explained above. This approach is designed toadapt to changes in the business environment and torespond to the market quickly by identifying only
functions that are actually used based on lean thinking, namely, omitting useless designs and implemen­tations that go unused (such as documentation andduplicated work) (Fig. 2).
Typical ways to shorten the development period are
to apply concepts such as continuous integration and
DevOps and to utilize open source software (OSS).
To further speed up product development and achieveVol. 15 No. 2 Feb. 2017

a development speed on a par with competitors,
BizDevOps can be used to regularly obtain feedback
from the market as to whether or not we are headingin the right direction—ranging from the planningstage of new services to hypothesis testing of busi­
ness and technical problems. Through regular coop­eration between Biz and Dev, a new concept can becreated, and prototypes can be implemented rapidly.
Whether this concept is correct or not can be deter­
mined by applying a way of thinking based on test
marketing. Test marketing is done by releasing the
product quickly onto the market (from Ops) and see­ing how users respond to it and then gathering feed­
back. The Biz team then analyzes the feedback todetermine whether the project (hypothesis) was a suc­cess or not. In addition to applying this kind of lean
thinking, we must also apply agile thinking—namely,
considering the ever-changing external environment,
upgrading specifications, quickly creating concepts
and operational software deemed acceptable by themarket and gathering feedback about them from cus­
tomers, deepening our understanding, and applying
shrewd modifications—as an effective measure forteam building to closely connect the Biz, Dev, andOps parts of a One Team. As for what is more difficult
about BizDevOps in comparison to DevOps, we cansimply presume that it is more difficult to achieve
mutual understanding among three groups with dif­fering values than it is to do so between two groups
with differing values.
2Feature Articles

Business department(Biz)

Seniormanagers(1) Marketing(2) Planning(6) Feedback(utilization status,
demands, etc.)(3) Development

Development
department (Dev)(4) Testing andreleaseOne Team

Clients andend users(5) Support

Operations
department (Ops)

Fig. 2. BizDevOps and One Team.

1.3 BizDevOps
The BizDevOps concept is based on the Scrum wayof thinking [1]. Scrum is an iterative and incremental
software development approach. It involves coopera­
tive work between people serving in three roles: thedevelopment team, the product owner, and the Scrum
master. This Scrum way of thinking is extended toinclude the Biz, Dev, and Ops departments. To build
teams that combine players with differing sets of val­
ues and cultures from the Biz component as well as
the Dev and Ops components, it is essential to attaineven more self-organization. Here, self-organizationrefers to a state in which one’s best level can beautonomously mobilized under the environment inwhich each person is placed. It is a state under which
self-motivated deeds are done naturally; everyone
does their best to achieve mutual understanding andcooperation from other team members in order toaccomplish the objectives of the entire team. Forminga One Team in which each member of a mixed team
based on BizDevOps is self-organized makes it pos­sible to substantially improve the success rate ofprojects.
We are focusing on the start-up stage of projects as
the first step in adopting BizDevOps and testing andproposing effective measures for building self-orga­
nized One Teams that will have a significant effect on
the success or failure of projects. While referencing
self-organization and team building based on Scrum,
we aim to create mutual understanding among thethree representatives in each team and to rapidly
3change their mindset from the conventional approach(usually the waterfall method) to the new approach.
As a tangible action of this first step, we perform
Scrum trials in virtual projects. By looking at how webehave when conventional methods no longer fit,
how we choose tasks spontaneously (tasks are notassigned to us), how we ease friction and increase
mutual understanding, and how we look back on our­selves (using the KPT (Keep, Problem, Try) method[2] framework that helps us organize and process our
behavior), we analyze how we behave when we are
self-organized by objectively acknowledging our
behavior.
Teams that went through the Scrum trials acquired
a lot of knowledge. Later on, they held workshops toteach other teams who needed to learn the knowledge
they had acquired. The workshops are condensed intoa maximum of ten days and involve not only typicalclassroom lessons and on-the-job training but also
efforts to instill the mindset and skills needed for lean
and agile software development. All team members
actively participate in a workshop while building up
and exchanging know-how in their own team. Thus,
the aim of the workshops is to achieve agile teambuilding that drives a smooth transition to actual
projects (Fig. 3). Moreover, the teaching team mem­bers find out more information and reach a deeper
understanding through the efforts passed on to otherteams; consequently, this self-organized team-build­ing achieved through repetition can grow and expand.
For those with experience in waterfall development,
NTT Technical Review

Feature Articles“I don’t know
where I should
start!”

Conventional
waterfalldevelopment team

One Team“I’m uneasy
about classroom
learning.”

Lean and agile development idea
• Design thinking/user experience/user interfaces• Agile development (Scrum)

One Team workshop

Lean and agile
development team

“I’ve mastered the actual
procedures and acquired
the understanding
concerning Scrum.”

One TeamAcquiring know-how by developing
virtual projects• Materials for developing simple
applications• Self-organization experience“Now I’m aware of the difference
from the waterfall way of doing
things.”Fig. 3. Depiction of One Team workshop.

switching to a lean and agile thought process involves
some confusion and resistance. However, by com­paratively analyzing that different experience basedon real-life experience and shifting one’s thoughtprocess in accord with the essence of the know-how
acquired, participants derive practical methods that
help to formulate an understanding that is a great deal
more agile than zero comprehension. Team members
who can fully and effectively apply their strong
points (including the beneficial aspects of the water­
fall approach) are brought together, and methods forquickly starting up a One Team are established.
2. Applying lean and agile thinking tolarge-scale development
If a project manager in charge of developing an
information system were given a task to complete a
project that would normally take five years (estimatedfive years of manpower) in only one year, what meth­ods would he/she use? Such a project would takemore time to complete if the design was complicated.
However, the longer it took to complete, the less users
would be interested by the time the initial detailed
design was developed and the product was released
onto the market. It is therefore necessary to come up
with measures to maintain the interest of users(Fig. 4). For a large-scale system to maintain its highadded value, we need a new method to quickly review
the system.
Hereafter, we describe a framework for linking thelean and agile way of thinking ascribed by the abovementioned BizDevOps approach and a way of think­ing called conceptual data modeling [3], which has
Vol. 15 No. 2 Feb. 2017

been successfully applied to development of largescale re-engineering.
Differing teams from the Biz, Dev, and Ops depart­ments eliminate duplication and nonconformity
between subsystems operated by each team and uti­
lize conceptual data models to understand the holistic
information (i.e., the big picture) needed to support
the development and operation of the system after
setting up One Teams. The data model used in thiscase is an autonomously aligned conceptual model.
2.1 Linkage of autonomously aligned conceptualmodel
We propose methods to implement large-scale
development in an extremely short time in order toquickly adapt to changes in the external environment.
In concrete terms, a system under development isdivided into subsystems of suitable scale, and multi­
ple teams (one for each subsystem) develop eachsubsystem in an iterative and incremental manner inparallel. Instead of devoting a long time to designing
everything exactly and rigorously, self-organized
One Teams are promptly set up, and each team carries
out their own development autonomously (but in par­allel with the others). Each small independent teamdevelops their partial systems while receiving feed­back from concerned users, and this process may
speed up the software development. Related users are
Biz and Ops (which evaluate and accept functions) as
well as other Dev teams in related fields. Fine-tuningis necessary to make sure each subsystem conforms
to the others, and efficient communication between
the One Teams is essential to do this fine-tuning.
Accordingly, a protocol for sharing the autonomously
4Feature Articles• PEST analysis(external factors are always fluid)

My Number (social
security number) system
TPP

AI + IoT

Decline inbirth rate

• Completion of release in one year
• Frequently susceptible to changes inexternal circumstances

Various social
problems

Economic shocks Significant points• Completion takes five years,
high quality• Susceptibility to changes in external
circumstances is a problem.

Invested time
1 year

5 years• Autonomous distributed
development of multiple lean andagile development teams
AI: artificial intelligence
IoT: Internet of Things
PEST: political, economic, social, and technological
TPP: Trans-Pacific Partnership

Fig. 4. Differences between proposed method and waterfall method.

aligned conceptual model (hereafter, simply “themodel”) was established in order to oversee the big
picture (i.e., the whole system) in a short time andplainly comprehend the work of other teams.
The model succinctly clarifies the key concepts of
the whole system and the relationships between them,and it is therefore effective because it enables eachteam developing their own subsystem to work togeth­
er to: (i) determine pointless duplication, (ii) deter­mine complicated relationships, and (iii) specify
areas to be independently managed. An example ofdetecting overlapping structures in data (bad structure detection) (Fig. 5) is explained in the following
subsection. In general, the people who oversee anentire large-scale system are limited to a few skilledhands. Even so, the application of the model to showholistic information in this manner means that infor­
mation can be shared rapidly in appropriate amounts.
5

As a result, communication between parallel teams
becomes efficient and well suited to simultaneous
parallel development.
2.2 S upporting transformation from bad to goodstructures
Let us suppose that the whole system is separated
into n individual regions (subsystems and develop­
ment teams). Ordinarily, there are many dependence
relationships between n subsystems. In the course of
autonomous development, it is likely that interfaces(IFs) between subsystems will be frequently modi­
fied. It is thus necessary to pay attention to suchmodifications, thereby placing a considerable load oneach development project. Accordingly, elements that
require monitoring of changes to IFs between sys­
tems and maintenance of consistency are given over
to tools. These tools provide overviews of an entire
NTT Technical Review

Feature Articles

Maintenance of consistency byusing autonomously aligned
concept model
Organization
Outsideemployees
Temporarystaff

Contract

Employees

Property

Detection ofbad structure

Detection ofbad structure

Detection ofbad structure

Autonomously aligned
concept model

Changetracking

Developer

Autonomous
Rapid
Repeated
Lean and agile development

ReviseDeveloper

Developer

ImpactImpactImpactDeveloper

Developer

External factor changes are rapidly
and autonomously assimilated in thedeveloping system.

Data with duplications,nonconformities,
and complex relationships

Development of autonomously
distributed systems

Data without duplications,nonconformities,
or complex relationships

Fig. 5. Lean and agile development utilizing autonomously aligned concept model.

development project for each development team,monitor nonconformities (bad structures) between
divided subsystems, and support transformations to
consistent states (good structures).
Examples of bad structures are relationships
involving duplication of concept model structures,
nonconformities, discrepancies, and complications,as shown in Fig. 6(a). In contrast, a concrete example
of a good structure is a simply organized structurethat is compatible with the concept model, as shownin Fig. 6(b). We prototyped a function for supportingtransformation to good structures by automaticallydetecting bad structures from this overview as adesign tool (Fig. 5). By reducing workloads by hav­
ing the developer orchestrate workloads between
workers, each team can concentrate on the develop­
ment work in their autonomous region, which will
improve work efficiency.
Moreover, before and after developing the modeltransformation of bad structures to good ones, we
prototyped a function for estimating initial runningcosts and evaluating designs. This function makes it
possible to rapidly spot nonconformities between
data models of the interior and exterior of subsystems
and to continuously maintain conformity of thewhole system while carrying out the parallel develop­
Vol. 15 No. 2 Feb. 2017

ment of each subsystem in a lean and agile manner.
The reduction in the initial running costs before andafter eliminating nonconformities can be estimated,
and that estimate can be effectively utilized as infor­
mation necessary for making decisions.
3. Concluding remarks
BizDevOps—a development approach used bybusinesses for analyzing their adaptability to changes
in the external environments and for speeding up
development through the establishment of One
Teams—was described in comparison with the con­ventional approach. Furthermore, we proposed amethod for rapidly coordinating development teams
while receiving feedback from the external environ­ment and customers as an alternative to re-engineer­ing for traditional large-scale systems, which requires
a long development time.
The main purposes of this proposal are threefold:(i) to increase the speed of development to rapidly
adapt to changes in external environments; (ii) to
broaden methods for detecting internal and externalchanges and accommodating those changes into thedevelopment scheme; and (iii) to rapidly create ser­vices based on the detection results and strengthen
6Feature Articles

Autonomously aligned
concept model(a) Status before maintenance ofconformity by using autonomouslyaligned concept model(bad structure present)

Each subsystem

Redundant
subsystems
are eliminated.

(b) Status after maintenance ofconformity by using autonomouslyaligned concept model(no bad structures)

Data with duplications,nonconformities,
and complex relationships
Redundant data structures ()

are gathered in one place ().

Data without duplications,nonconformities,
or complex relationships

Fig. 6. Transforming faulty structures to ideal structures that can be detected.

competitiveness. As a means of combining a divideand-rule way of thinking with lean and agile thinking,a development method with which One Teams utilize
an autonomously aligned concept model for adjustingoverall conformity was devised.
A tool for automatically detecting bad structuresand supporting transformation to good structures isbeing prototyped in order to alleviate operational
adjustments to changes in model structures done
manually. Furthermore, we will continue to experi­
ment with and evaluate the proposed method as a new

7

development approach that can easily maintain over­all conformity while utilizing a cost-estimation func­tion and enabling autonomous and simultaneouswork in parallel.
References
[1]
[2]
[3]

Scrum guides, http://www.scrumguides.org/download.html
S. Amano, “KPT Is the Answer!”, Subarusya Linkage Corporation,
2013.
NTT Information Network Laboratory Group, “Database Conceptual
Design,” Abe Publishing Ltd., 1993.

NTT Technical Review

Feature Articles

Satoru Aihara

Takako Tanaka

Senior Research Engineer, Software Engineer­ing Project, NTT Software Innovation Center.
He received a B.E. in information technology
from Yamaguchi University in 1992. He joined
NTT DATA in 1992. His work has focused on thedevelopment of search engine and knowledge
management systems. His current research inter­
ests include software development processes.

Research Engineer, Software Engineering
Project, NTT Software Innovation Center.
She received a B.M.I.S in information sciencefrom Sanno University, Kanagawa, in 1998. She
joined NTT Software Corporation in 1998 as asoftware engineer. Her current interests include
software engineering.

Masayuki Inoue

Nagisa Sekiguchi

Senior Research Engineer, Software Engineer­ing Project, NTT Software Innovation Center.
He received a B.E. and M.E. in electrical engi­
neering from Tokyo University of Science in1994 and 1996, and a Ph.D. in engineering from
Tokyo Institute of Technology in 2008. He joined
NTT in 1996 and worked on the development of
3D cyberspace and video communication sys­tems. He is currently working on system analysis
in early phases using stored data in legacy sys­tems. His research interests also include userinteraction and video system evaluation. Dr.
Inoue is a member of the Institute of Electronics,
Information and Communication Engineers(IEICE).

Software Engineering Project, NTT Software
Innovation Center.
He received a B.E. and M.E. from Yokohama
National University, Kanagawa, in 2014 and2016. He joined NTT in 2016. His current inter­
ests include software engineering. He is a mem­ber of the Association for Computing Machinery.

Akio Jin

Senior Research Engineer, Supervisor, Soft­ware Engineering Project, NTT Software Inno­
vation Center.
He received a B.S. and M.S. in nuclear engi­
neering from Hokkaido University in 1987 and1989. He joined NTT in 1989. He has worked on
the development of telecommunication services
including PHS (personal handy-phone system),
2G/3G-mobile, and the Next Generation Net­
work. His current research interests include
software engineering. He is a member of IEICE.

Senior Research Engineer, Software Engineer­ing Project, NTT Software Innovation Center.
He received a B.E. and M.E. from Nagoya
University, Aichi, in 1992 and 1994, and a Ph.D.
from the University of Tsukuba in 2008. Sincejoining NTT in 1994, he has contributed to thedevelopment of the MPEG-4 TwinVQ audio
codec, a speech recognition system, and an auto­
matic program generation system. His current
research interests include upper software devel­
opment processes and structure estimation ofexisting systems. He received the Nikkei BP
Technology Award from Nikkei Business Publi­
cations, Inc., Japan, in 1997 and the Telecom
System Technology Award from the Telecom­
munications Advancement Foundation, Japan, in
1998.

Yoshinori Furukawa

Senior Research Engineer, Software Engineer­ing Project, NTT Software Innovation Center.
He received a B.E. and M.E. from Ritsumeikan
University, Shiga, in 1994 and 1996. He joined
NTT in 2014. His current interests include soft­
ware engineering.

Vol. 15 No. 2 Feb. 2017

Eiichi Oka

Keitaro Horikawa

Senior Research Engineer, Supervisor, Soft­ware Engineering Project, NTT Software Inno­
vation Center.
He received a B.S. and M.S. in informationengineering from Niigata University in 1988 and1990. He joined NTT in 1990. He received theBest Paper Award for young researchers at theInformation Processing Society of Japan national
convention in 1995. He has a Project Manage­
ment Professional certification from the ProjectManagement Institute and a TOGAF (The OpenGroup Architecture Framework) 9 certificationfrom the Open Group. His research interests
include software design and architecture, concur­
rent distributed object computing, meta-object
programming and computational reflection, sin­gle sign-on for web services, lightweight pro­gramming languages, mobile cloud computing
and big data processing, machine learning open
source projects, computer supported cooperative
work, computer supported collaborative learn­ing, game theoretic modeling for decision mak­ing, and human factors in research and develop­
ment.

8

Regular Articles

Graphene p-n Junction as an
Electronic Beam Splitter
Norio Kumada
Abstract

N-type and p-type regions in graphene can adjoin without a gap in between. This article explains how
such characteristic p-n junctions can serve as beam splitters of electrons. Utilizing the long coherence
length of electrons in graphene may make it possible to carry out an electron version of quantum optics.
Keywords: graphene, p-n junction, electron beam splitter

1. Introduction
Quantum optics is a field of research that investigates the wave-particle nature of light based on quantum mechanics, using interferometers consisting of
optical elements such as mirrors and beam splitters.
Knowledge obtained from quantum optics has been
applied to quantum cryptography and quantum teleportation. An electron is also a quantum having awave-particle nature like a photon and can thus create
interference. An important difference between an
electron and a photon is whether it is a fermion or aboson. This difference appears in their two-particle
interference.
Another important difference is the presence/
absence of the Coulomb interaction. The presence of
the Coulomb interaction for electrons has both positive and negative aspects; the electron quantum state
can be controlled through the interaction, but its
coherence is easily destroyed. The resulting shortcoherence length makes experiments on electron
quantum optics difficult to carry out.
Thus far, electron quantum optics has been conducted in the quantum Hall effect regime, whichappears under a magnetic field in two-dimensional
electron systems formed in GaAs/AlGaAs (gallium
arsenide/aluminium gallium arsenide) heterostructures. A narrow channel in these systems called aquantum point contact with an electron transmission
probability of 1/2 (Fig. 1(a)) is used as a beam splitter. A fundamental problem with these systems is the1

short coherence length of about 10 µm, which is comparable to the typical size of interferometers, limiting
experiments to the basic level. One way to solve thisproblem and carry out more advanced experiments is
to use graphene, in which the coherence length is expected to be longer. However, since graphene is a gaplessmaterial, beam splitters based on quantum point
contacts made by depleting local electrons do not work.
In this study, a team comprising members fromNTT Basic Research Laboratories and CEA Saclay
proposed a new beam splitter architecture using agraphene p-n junction and verified its performance.
Electrons in graphene that are injected from the n andp regions are mixed in the p-n junction and then partitioned at the exit of the junction (Fig. 1(b)). The
electron mixing and the subsequent partitioning processes can serve as a beam splitter. The behavior of
the beam splitter was verified by measuring the current shot noise.
2. Device fabrication and measurements
Graphene is generally obtained by exfoliating itfrom graphite. A drawback of this technique is thatthe graphene size is limited to several tens of micrometers. In contrast, the graphene we used was epitaxially grown by thermally decomposing the SiC (silicon carbide) substrate (Fig. 2(a)). SiC substrates
were annealed at ~1800°C in Ar (argon) at a pressureof less than 100 Torr. For the device fabrication,
graphene was etched in an O2 (oxygen) atmosphere.
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Regular Articles

p

B

B

n

(a)

(b)

Fig. 1. (a) Quantum point contact (QPC) in a standard semiconductor device, formed by a pair of split gates (yellow). The
transmission of the QPC is set to 0.5 so that electrons injected to the QPC are randomly transmitted or reflected tothe downstream channels (red and blue dashed lines). (b) Graphene p-n junction. Current channels from the n andp regions (red and blue lines, respectively) are mixed in the p-n junction (thick black line) and then partitioned at theexit of the junction. Therefore, electrons injected to the p-n junction are randomly distributed to the downstream
channels in the n and p regions (red and blue dashed lines).

1 cm
Si
C (graphene)
SiC(a)
Top gate
Ie

Ih

L
Preamp.

VG(b)Fig. 2. ((a) left) Photograph of graphene grown on SiC. ((a) right) Schematic of graphene growth on SiC. (b) Device structureof graphene with a p-n junction. Gray region represents n-doped graphene. Tuning the bias of the top gate (yellow
region) changes the carrier type in the gated region to a hole, and a p-n junction is formed at the interface between
the gated and ungated regions. Orange regions are ohmic contacts.

After etching, the surface was covered with 100-nmthick HSQ (hydrogen silsesquioxane) and 60-nmthick SiO2 (silicon dioxide) insulating layers. A p-njunction was made using a top gate covering half ofVol. 15 No. 2 Feb. 2017

the graphene. The ungated region was n doped, while
p carriers were introduced in the gated region. Therefore, a p-n junction was formed at the interface
between the gated and ungated regions (Fig. 2(b)).
2

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Current in the quantum Hall effect regime flows
along the edge of the graphene in a direction determined by the polarity of the magnetic field and thecarrier type (electron or hole). When a p-n junction isformed, counter-circulating edge channels of electrons and holes are mixed in the p-n junction and thenpartitioned at the exit of the junction. The mixing andthe subsequent partitioning processes serve as anelectron beam splitter; electrons injected from theelectron channel are randomly distributed to thedownstream electron and hole channels (Fig. 1(b)).
We tested the behavior of the beam splitter by measuring the current noise (shot noise) caused by the
random electron distribution. The results demonstratethat the random partitioning noise is present when ap-n junction is formed (solid and open cyan circles)
and absent when it is not (black circles), as shown in
Fig. 3. We further found that the amplitude of noise
increases as the p-n junction length decreases (Fig. 4).
This indicates that the energy relaxation length ofelectrons in a p-n junction is 15 µm. The amplitude ofnoise in a short p-n junction is consistent with beamsplitter behavior.
4. Future work
The architecture of a graphene p-n junction is simpler than that of a quantum point contact, which isused as a beam splitter in conventional semiconductors. This allows us to integrate several beam splitterswithin a mesoscopic scale in graphene. Utilizingthese beam splitters and long coherence length ingraphene would make it possible to fabricate complicated electronic interferometers. Experiments onthese devices would reveal the effects of the Coulombinteraction on decoherence. Furthermore, the generation of quantum entangled electron pairs is expected
to be achieved in such devices.

3

Excess noise (10−27 A2/Hz)

3. Behavior of graphene p-n junction as electron
beam splitter

1.0
With p-n junction

0.8

Without p-n junction
0.6
0.4
0.2
0.0
−4

−2

0
Vsd (mV)

2

4

Fig. 3. S hot noise generated by p-n junction as a functionof the bias applied to the electron channel Vsd. Solidcyan and black circles represent the measured
noise in the presence and absence of p-n junctions.
Open cyan circles represent the noise in thepresence of a p-n junction obtained by applying
bias to the hole channel.

10
Excess noise (10−27 A2/Hz)

We were able to fabricate devices with different p-njunction lengths between 5 and 100 µm by exploiting
the wafer-size graphene.
All measurements were carried out in a quantum
Hall effect regime, which was created by applying amagnetic field perpendicular to graphene at a lowtemperature of 4 K. The noise measurement involved
converting the current noise into voltage fluctuations
across one 2.5-kΩ resistor in series with the sample.

5 µm
10 µm
20 µm
50 µm
100 µm

8
6
4
2
0
−4

−2

0
Vsd (mV)

2

4

Fig. 4. S hot noise for different values of p-n junction length
as a function of the bias applied to the electron
channels Vsd.

This work was done in collaboration with NTT
Basic Research Laboratories and CEA Saclay. Complementary results achieved by a group from Osaka
University, Kyoto University, and the National Institute for Materials Science have been published simultaneously [2].

NTT Technical Review

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References[1]

N. Kumada, F. D. Parmentier, H. Hibino, D. C. Glattli, and P.
Roulleau, “Shot Noise Generated by Graphene p–n Junctions in the
Quantum Hall Effect Regime,” Nat. Commun., Vol. 6, 8068, 2015.

[2]

S. Matsuo, S. Takeshita, T. Tanaka, S. Nakaharai, K. Tsukagoshi, T.
Moriyama, T. Ono, and K. Kobayashi, “Edge Mixing Dynamics inGraphene p–n Junctions in the Quantum Hall Regime,” Nat.
Commun., Vol. 6, 8066, 2015.

Norio Kumada

Senior Research Scientist (Distinguished Scientist), Quantum Solid-State Physics ResearchGroup, Physical Science Laboratory, NTT Basic
Research Laboratories.
He received a B.S., M.S., and Ph.D. in physics
from Tohoku University, Miyagi, in 1998, 2000,
and 2003. He joined NTT Basic Research Laboratories in 2003. He has since been engaged in
the study of highly correlated electronic statesachieved in semiconductor heterostructures. He
was a visiting researcher at CEA Saclay during
2013–2014. He was appointed as a Distinguished
Scientist of NTT in 2010. He received the Young
Scientist Award of the Physical Society of Japan
in 2008 and the Young Scientists’ Prize from the
Minister of Education, Culture, Sports, Scienceand Technology in 2012. He is a member of the
Physical Society of Japan.

Vol. 15 No. 2 Feb. 20174

Regular Articles

World’s Highest Density OpticalFiber for Space Division Multiplexing
with Deployable Reliability
Taiji Sakamoto, Takashi Matsui, Shinichi Aozasa,
Kyozo Tsujikawa, and Kazuhide Nakajima
Abstract

Space division multiplexing (SDM) technology has been intensively investigated in order tosubstantially increase the network capacity of optical fiber telecommunication. Multi-core or multimode fiber is a promising candidate for next-generation optical fiber. In this article, we describe our
optical fiber for SDM transmission that can realize 100 times larger capacity than that of standard singlemode fiber while maintaining deployable mechanical reliability.
Keywords: optical fiber, space division multiplexing, multi-mode multi-core

1. Introduction
Existing telecommunication networks mainly utilize single-mode fiber (SMF), whose low loss andbroadband characteristics have resulted in increased
network transmission capacity. The progress in thecapacity per optical fiber of the core network in Japanis shown in Fig. 1. The transmission capacity has
steadily increased year by year, and the rate ofincrease grew by 1000 times in a 20-year period(from 1.6 Gbit/s in 1987 to 1.6 Tbit/s in 2007). This
rapid increase in capacity is due to the developmentof transmission technologies such as time divisionmultiplexing and wavelength division multiplexing,
as well as the development of optical amplifiers suchas erbium-doped fiber amplifiers.
A transmission system using digital coherent technology was recently introduced, and 8-Tbit/s capacity
has been achieved by using a multi-level modulation
format with high spectral efficiency. However, it isexpected that the capacity limit of the standard SMF
is around 100 Tbit/s [1]. Therefore, it is necessary todevelop a new transmission medium to achieve 1000
times larger capacity in the next 20 years. Space division multiplexing (SDM) technology using multi1

core or multi-mode fiber has been intensively investigated as a promising candidate for a next-generationtransmission system. In the following section, we
report our latest research results on the developmentof optical fiber for an SDM system taking the spatial
density and mechanical reliability into account.
2. Optical fiber for SDM system
Multi-core and multi-mode fibers are depicted in
Figs. 2(a) and (b). Multi-core fiber has multiple coreswithin a cladding, and multiple signals can be transmitted in parallel by using multiple cores. Multimode fiber typically has a larger core than that of
SMF, and multiple modes can propagate within acore. Each mode is orthogonal to each other and istreated as an independent transmission path. Thus,
mode division multiplexing (MDM) is realized,
where multiple signals can be transmitted throughmultiple modes.
Multi-mode multi-core fiber has been studied
recently in order to achieve ultra-high capacity transmission. This fiber combines multi-core and multimode technologies. The structure of the multi-mode
multi-core fiber is shown in Fig. 2(c). There are multiple
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Space division multiplexing

Transmission capacity
per fiber (bit/s)

1P
100T
10T

Capacity limit of SMF
Digitalcoherent

WDM
EDFA

1T
100G
10G

TDM

1G
100M
1980

1990

2000

2010

2020

2030

2040

Year
EDFA: erbium-doped fiber amplifier
TDM: time division multiplexing
WDM: wavelength division multiplexing

Fig. 1. Progress in transmission capacity per optical fiber.

Single-mode
core(a) Multi-core fiber

Multi-mode
core(b) Multi-mode fiber

Multi-mode
core(c) Multi-mode multi-core fiber

Fig. 2. Schematic diagram of multi-core and multi-mode fibers.

2.1 Mechanical reliability
Failure probability, which means the probability
that a fiber will be broken, increases as the fiber diamVol. 15 No. 2 Feb. 2017

140
Number of transmission
channels per fibercores, and multiple modes can propagate within eachcore. This enables us to employ MDM transmission
using each core. As a result, m×n transmission channels are obtained with n-mode m-core fiber.
The transmission channels per fiber as a function offiber diameter of recently reported multi-core fiber
are shown in Fig. 3. The results for multi-core fiberwith single-mode cores and multi-mode cores arerespectively plotted as open and solid circles. It canbe seen that the multi-mode multi-core fiber makes it
possible to achieve substantially more transmission
channels compared to single-mode multi-core fiber.
In fact, more than 100 transmission channels can beobtained with multi-mode multi-core fiber. However,more transmission channels results in a larger fiber
diameter. Next, we describe some important parameters when designing the SDM fiber.

120

Single-mode multi-core fiber
Multi-mode multi-core fiber

100
80
60
40
20
0
100

150

200

250

300

350

Fiber diameter (µm)

Fig. 3. R elationship between transmission channels per
fiber and fiber diameter.

eter increases when fiber is bent owing to the inherent
nature of the glass. A failure in a transmission line
causes a disconnection of the network service and2

Regular Articles

19

13

14

15

16

18

×2

8

9

10

11

12

4

5

6

7

1

2

3

×2

17

Six modes can propagate within each core.

Fig. 4. Cross section of fabricated 6-mode 19-core fiber.

should be avoided so as not to degrade the network
reliability. Thus, the fiber diameter cannot be
increased in an unlimited fashion in order to deploy alarger number of cores, and a fiber diameter designthat maintains flexibility and reliability is required.
2.2 Spatial density
It is important for the telecom operator to design amulti-core fiber with the cores packed as closely as
possible because we need to efficiently utilize thelimited space of the telecom infrastructure such as thecable duct space underground. The spatial density,
namely the number of cores per unit area, is one ofthe parameters used to evaluate the density.
2.3 Transmission characteristics
The transmission channels in the SDM fiber need tohave better performance than those of the SMF. Thismeans that the SDM fiber should have low transmission loss characteristics comparable to the SMF, andthe inter-core crosstalk should be suppressed by properly designing the distance between neighboringcores. The differential mode delay (DMD) is also an
important parameter for multi-mode multi-core fiber.
DMD is the group delay difference between the
propagation modes. The propagation modes typicallyhave different group velocities. Reducing the DMD
in an MDM system is strongly required because it
becomes more difficult to recover the transmitted
signals at the receivers when the DMD is large.
3. Fabricated fiber with world’s highest
spatial density
A cross section of the fabricated fiber is shown in
3

Fig. 4. It has a hexagonally arranged 19-core structure with 6-mode cores, and there are 114 transmission channels per fiber in total. This fiber has thefollowing advantageous features.
3.1 Deployable mechanical reliability
Our fiber was designed to have a suitable fiber
diameter for maintaining deployable mechanical reliability. The relationship between the fiber failure
probability and fiber diameter is shown in Fig. 5. It isclear that an increase in the fiber diameter causes anincrease in failure probability, which reduces the reliability of the fiber. Fiber reliability depends on thebending radius and proof testing as well as the fiber
diameter. Proof testing is a process to improve thereliability of the fiber by applying longitudinal stressto the fiber during the fabrication process. A 1–2%
proof level is commonly used in the current manufacturing process, and a bending radius of less than 15
mm is assumed for recent high density optical fiber
cable design, so we have targeted a fiber diameter ofless than 250 μm to obtain the same mechanical reliability as that of SMF. The fabricated fiber has a fiber
diameter of 246 μm. Thus, deployable mechanicalreliability for a telecommunication network is
obtained.
3.2 Highest spatial density
Our fiber has the world’s highest spatial density
among reported SDM fibers. To achieve this, weinvestigated the optimum core structure to incorporate the transmission channels efficiently within afiber diameter of less than 250 μm. The relationshipbetween the spatial density and the fiber diameter ofvarious multi-mode multi-core structures is shown in
NTT Technical Review

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Proof level 1%
Proof level 2%15-mm bending
radiusLow

1
Reliability

Normalized fiber failure
probability based on SMF

10x

1/10

1/100
100

High

125 150
SMF

175

200

225 250 275 300
Our target max. diameter
Fiber diameter (µm)

Fig. 5. Relationship between fiber failure probability and fiber diameter.

Normalized spatial density

70
(114)

60

(126)

(72)
50
40
30

(36)

(48)

(72)

20
10
190

210

230
250
Fiber diameter (µm)

270

Fig. 6. Relationship between spatial density and fiber diameter of various multi-mode multi-core structures.

Fig. 6. The number of spatial channels is noted inparentheses. Here, the spatial density is the number oftransmission channels divided by unit area of thecross section, and it is normalized by that of SMF. We
assumed 12–21 core structures with 3-mode cores(red symbols) or 6-mode cores (blue symbols). We
found that 6-mode multi-core fiber can achieve larger
spatial density than that of 3-mode multi-core fiber,
and the 6-mode 19-core structure can be obtained
within a fiber diameter of less than 250 μm. We fabricated the 6-mode 19-core fiber as shown in Fig. 4
and achieved the world’s highest spatial density ofmore than 60.

Vol. 15 No. 2 Feb. 2017

3.3 O
 ptical properties suitable for long-haultransmission
Our fiber has suitable optical properties for longhaul transmission owing to the well-controlled fabrication process. The refractive index profile of thecore is shown in Fig. 7(a). It has a graded index corewith a low index trench. The graded index core profile enables us to reduce the DMD, and the low index
trench can reduce the inter-core crosstalk. The transmission loss as a function of the DMD value ofreported multi-mode multi-core fibers is plotted inFig. 7(b). As shown in the graph, our fiber had thelowest loss (less than 0.24 dB/km) and DMD (lessthan 0.33 ns/km) among various fibers. In addition,
the inter-core crosstalk was suppressed below
4Regular Articles

0.55
0.5

Graded index core
Loss (dB/km)

0.45
0.4
0.35
0.3
0.25

Our fiber(Loss <0.24 dB/km, DMD <0.33 ns/km)

0.2
Low index trench

0.15

0

1

2

3

4

5

6

7

8

DMD (ns/km)
(a)

(b)

Fig. 7. (a) Schematic diagram of trench assisted graded-index core profile, (b) transmission loss vs. DMD of recently
reported few-mode multi-core fibers.

–30 dB/100 km, which corresponded to having thepotential to transmit quadrature phase shift keying(QPSK) signals over 1000 km with negligible power
penalty induced by the crosstalk. We experimentallyconfirmed that QPSK signals through 114 transmission channels were successfully transmitted over an
8.85-km-long fiber [2]. This indicates that our fiber
has suitable transmission characteristics for longhaul SDM networks.

5

References
[1]

[2]

T. Morioka, “New Generation Optical Infrastructure Technologies:
EXAT Initiative Towards 2020 and Beyond,” Proc. of OECC
(OptoElectronics and Communications Conference), FT4, Hong
Kong, July 2009.
T. Sakamoto, T. Matsui, K. Saitoh, S. Saitoh, K. Takenaga, T. Mizuno,
Y. Abe, K. Shibahara, Y. Tobita, S. Matsuo, K. Aikawa, S. Aozasa, K.
Nakajima, and Y. Miyamoto, “Low-loss and Low-DMD Few-mode
Multi-core Fiber with Highest Core Multiplicity Factor,” Proc. of
OFC (Optical Fiber Communication Conference), Th5A.2, Anaheim,
CA, USA, Mar. 2016.

NTT Technical Review

Regular Articles

Taiji Sakamoto

Kyozo Tsujikawa

Research Engineer, NTT Access Network Service Systems Laboratories.
He received a B.E., M.E., and Ph.D. in electrical engineering from Osaka Prefecture University in 2004, 2006, and 2012. In 2006, he joined
NTT Access Network Service Systems Laboratories, where he has been conducting research on
optical fiber nonlinear effects, low nonlinear
optical fiber, few-mode fiber, and multi-core
fiber for optical multiple-input multiple-output
transmission systems. Dr. Sakamoto is a memberof the Institute of Electronics, Information andCommunication Engineers (IEICE).

Senior Research Engineer, NTT Access Network Service Systems Laboratories.
He received a B.S. and M.S. in chemistry, anda Ph.D. in engineering from Tokyo Institute ofTechnology in 1990, 1992, and 2006. Since joining NTT, he has undertaken research on glassmaterials for low-loss optical fibers, measurement of optical fibers, and measurement of optical properties of fiber cables. Dr. Tsujikawa is amember of IEICE.

Takashi Matsui

Kazuhide Nakajima

Senior Research Engineer, Access Media Project, NTT Access Network Service Systems Laboratories.
He received a B.E., M.E., and Ph.D. in electronic engineering from Hokkaido University in
2001, 2003, and 2008. He also attained the statusof Professional Engineer (P.E.Jp) in electricaland electronic engineering in 2009. In 2003, hejoined NTT Access Network Service Systems
Laboratories, where he researches optical fiber
design techniques. Dr. Matsui is a member of
IEICE.

Senior Research Engineer, Supervisor (Distinguished 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 Rapporteur Q5/SG15 of ITU-T. Dr.
Nakajima is a member of IEICE, IEEE, and the
Optical Society of America.

Shinichi Aozasa

Senior Research Engineer, NTT Access Network Service Systems Laboratories.
He received a B.S. and M.S. in chemistry from
Hokkaido University in 1996 and 1998 and a
Ph.D. in engineering from the University ofTokyo in 2008. In 1998, he joined NTT OptoElectronics Laboratories, where he researchedand developed optical fiber amplifiers and planar
lightwave circuits used in high-capacity opticaltransmission. In 2014, he joined NTT AccessNetwork Service Systems Laboratories, where
he has been researching optical fiber and its fabrication process. Dr. Aozasa is a member of
IEICE and the Institute of Electrical and Electronics Engineers (IEEE).

Vol. 15 No. 2 Feb. 20176

Global Standardization Activities

Quality Estimation Technique forVideo Streaming Services
Kazuhisa Yamagishi and Akira Takahashi
Abstract

The use of adaptive bitrate video streaming services over the network is increasing. The quality ofthese services is affected by video resolution, audio and video bitrates, bitrate adaptation, stalling due tothe lack of playout buffer, and content length. Therefore, service providers need to monitor quality inreal time in order to verify that their services are functioning normally. A model that can be used to estimate quality is necessary in order to accurately monitor quality. This article introduces a quality estimation technique that assesses user quality of experience of audiovisual content in adaptive bitrate streaming services.
Keywords: adaptive bitrate streaming, quality of experience, quality estimation

1. Introduction

2. ITU-T SG12

The use of adaptive bitrate streaming over the network has recently been increasing. HTTP (Hypertext
Transfer Protocol)-based adaptive bitrate streaming
provides users with the best possible quality of experience for various network conditions because theclient application can adaptively select a media filewith a suitable bitrate.
Streaming quality degrades due to compression andnetwork conditions (e.g., packet loss, insufficient
bandwidth, delay, and jitter). When a reduction inthroughput occurs, the quality level that is best suitedunder current network conditions can be selected(known as adaptation) because there are several files(i.e., chunks/segments) corresponding to representations of different bitrates on the server. The throughput is reduced, and packet delay and jitter are introduced due to network congestion. As a result, theplayout buffer slowly fills or depletes. When the buffer is empty, the playback of the audiovisual content
is interrupted until sufficient data for playback arereceived (Fig. 1). Therefore, it is important to monitor
the normality of streaming services.

The quality of adaptive bitrate video streaming isaffected by compression degradation, adaptation, andstalling events. Therefore, it is important to monitor
quality at the client application as well as the qualityof servers and networks.
In-service quality monitoring is an important application for quality estimation. An example of this is todetect the locations where quality has degraded bygathering a large amount of quality data throughcloudsourcing. Also, even when users do not noticedegradation due to compression or network congestion, the quality estimation technique can detect small
amounts of degradation. Therefore, service providers
can quickly improve their services by using thedetected information.
The International Telecommunication Union Telecommunication Standardization Sector Study
Group 12 (ITU-T SG12) has been studying a quality
estimation model for adaptive bitrate video streaming
and will standardize it in 2017. This model is called
the parametric non-intrusive assessment of TCPbased multimedia streaming quality (P.NATS)(Fig. 2).
The P.NATS model consists of four modules:
1) Parameter extraction module

1

NTT Technical Review

Global Standardization Activities

Acquisition

Editing

Encoding
Network• Compression • Packet loss, delay, jitter
distortion• Throughput variations

Decoder• Play-out buffer

Viewing

Fig. 1. Quality degradation factors.

Parameter
extraction

StreamMedia
parameter
extraction

Bufferingparameter
extraction

Media quality
estimation
Audio
qualityestimation
moduleVideoqualityestimation
moduleQuality
integration
moduleAV
integration/temporal

Quality
impactdue tobufferingMediasession
quality

AV: audiovisualFig. 2. Recommendation P.NATS model proposed by ITU-T.

This module receives and acquires information
about the audio and video bitrates, resolution, andframerate per chunk, measures the rebuffering timing and duration, and calculates stall-relatedparameters using rebuffering information.
2) Audio quality estimation moduleThis module estimates audio quality per 1-second
sampling interval using the audio bitrate.
3) Video quality estimation moduleThis module estimates video quality per 1-second
sampling interval using the video resolution, frame­
rate, and bitrate.
4) Quality integration moduleThis module takes audio and video quality andstalling parameters as input and estimates final
media-session quality.
Accurate estimation of the quality of adaptive
bitrate video streaming requires accurate estimationof audio and video quality. Moreover, quality adaptation due to throughput variation and stalling events
due to the lack of a playout buffer need to be taken
into account.
To verify the accuracy of the quality estimation
Vol. 15 No. 2 Feb. 2017

models, ITU-T SG12 analyzed the results of 30 subjective quality assessment tests submitted by sevenorganizations from seven countries. In the subjective
tests, audiovisual content was encoded using
Advanced Audio Coding - Low Complexity (AACLC) [1] (bitrate: 24–196 kbit/s) and H.264/Advanced
Video Coding (AVC) [2] (bitrate: 75 kbit/s–12.5
Mbit/s; pixel resolution: 426 × 240–1920 × 1080;
framerate: 7.5–30 fps), and various types of stalling
events were added. The models proposed by DT/TLabs, Ericsson, Huawei, NetScout, NTT, Opticom,
and SwissQual were equal in the statistical analysis,and ITU-T SG12 therefore agreed to develop a single
model by merging these models.
3. Outlook
This article described the P.NATS model that can beused to estimate the quality of adaptive bitrate video
streaming services and that will be standardized in2017. In the next step, ITU-T SG12 will standardize
a P.NATS Phase 2 model that can be used for estimating the quality of 4K-ultrahigh definition content
2Global Standardization Activities

References

encoded by H.264/AVC, H.265/High Efficiency
Video Coding (HEVC), and VP9.
[1]
[2]

Kazuhisa Yamagishi

Senior Research Engineer, NTT Network
Technology Laboratories.
He received a B.E. in electrical engineeringfrom Tokyo University of Science in 2001 and an
M.E. and Ph.D. in electronics, information, andcommunication engineering from Waseda University, Tokyo, in 2003 and 2013. He joined NTT
in 2003. He has been engaged in the developmentof objective quality estimation models for multimedia telecommunications. He has been contributing to ITU-T SG12 since 2006.

3

ISO/IEC 13818-7: “Information technology -- Generic Coding ofMoving Pictures and Associated Audio Information -- Part 7:
Advanced Audio Coding (AAC),” Jan. 2006.
ITU-T Recommendation H.264: “Advanced Video Coding for Generic Audiovisual Services,” Oct. 2016.

Akira Takahashi

General Manager, Planning Department; Project Manager, Telecommunication Traffic &Quality Project, NTT Network Technology Laboratories.
He received a B.S. in mathematics from Hokkaido University in 1988, an M.S. in electricalengineering from California Institute of Technology, USA, in 1993, and a Ph.D. in engineeringfrom University of Tsukuba, Ibaraki, in 2007. He
joined NTT in 1988. He has been contributing to
ITU-T SG12 on performance, quality of service,and quality of experience since 1994. He was a
Vice-Chairman of ITU-T SG12, a Vice-Chairman of Working Party 3 in SG12, and a CoRapporteur of Question 13/12 for the 2009–2012
and 2013–2016 study periods.

NTT Technical Review

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

Fax Transmission Failure Analysis
Method Requiring Multi-signal
Analysis
Abstract

This article describes a problem a customer had involving facsimile transmission failure and how it
was resolved through analysis of multiple signals. This is the thirty-eighth article in a series on telecommunication technologies. This contribution is from the Network Interface Engineering Group, Technical
Assistance and Support Center, Maintenance and Service Operations Department, Network Business
Headquarters, NTT EAST.
Keywords: facsimile, IP network service, echo

1. Introduction
The Network Interface Engineering Group provides technical support in relation to Internet protocol(IP) network services such as FLET’S HIKARI
NEXT. This includes analyzing the Ethernet interface
between terminal equipment and telecommunications equipment as well as analog line and ISDN
(Integrated Services Digital Network) interfaces
comprising gateways and private branch exchange(PBX) equipment.
We introduce here a case study in which we applied
our analysis methods to determine why a Group 3(G3) facsimile (fax) machine accommodated by PBX
equipment would sometimes fail to transmit fax data
to a specific party.
2. Case study overview andinvestigation method
The customer was using a G3 fax machine connected to PBX equipment. The customer found thatthe transmission of fax data from this machine to a
specific party would occasionally fail.
The approach taken by maintenance personnel in1past cases of fax machine transmission problems wasto replace the outer-line package for Hikari Denwa
use or the extension package for fax use housed
within the PBX equipment, or to change the transmission level of the fax signal. This time, however, theproblem could not be solved with that approach, andthe Technical Assistance and Support Center was
asked to investigate the cause of the problem.
To collect data at the time of failure occurrence, we
installed packet capture equipment in the Ethernet
interval and a G3 facsimile tester in the analog line
interface and proceeded to collect and analyze IP
packets and fax signals (Fig. 1).
3. Analysis of collected data
(1) Ethernet
No anomalies were found in the Session Initiation
Protocol (SIP) communication sequence for Hikari
Denwa call control. In addition, no packet losses orabnormal packet arrival intervals that could cause thefailure could be found in the Real-time Transport
Protocol (RTP) packets carrying the fax signal.
(2) Analog line interface
The sender fax communication sequence of the
NTT Technical Review

Practical Field Information about Telecommunication Technologies

Capture point (Ethernet)
G3 facsimile tester (analog line interface)
Sender fax

Receiver fax
HGW

Outer-line PKG

FailureONU

Hikari Denwa
network
ONU

Extension PKG

PBX

HGW: home gateway
ONU: optical network unit
PKG: package

Fig. 1. Connection configuration and data-collection points.

Send

CNG

Receive

Send

CNG

Receive

CED

CED

DIS NSF/CSIDIS NSF/CSI

TSI/DCS

TSI/DCS

TCF

TCF

CFR

CFR

Image signal

Image signal

EOP

DCN

EOP
EOP
DCN
(a)
CED: called terminal identification tone
CFR: confirmation to receive
CNG: calling tone
CSI: called subscriber identification
DCN: disconnect command
DCS: digital command signal(b)
DIS: digital identification signal
EOP: end of procedure
NSF: nonstandard facility
TCF: training check function
TSI: transmitting subscriber identification

Fig. 2. (a) Sender fax communication sequence; (b) receiver fax communication sequence.

reporting customer and the receiver fax communication sequence of the other party as collected by theG3 facsimile testers are shown in Fig. 2.
(3) Sender fax communication sequence
The sender fax sends an EOP (end of procedure)
signal after sending the image signal. However, as no
MCF (message confirmation) signal is received fromthe receiver fax, the sender fax sends a DCN (disconnect command) signal and disconnects the communiVol. 15 No. 2 Feb. 2017

cation (Fig. 2(a)).
(4) Receiver fax communication sequence
After receiving the image signal, the receiver fax
sends a DCN signal before receiving an EOP signal
from the sender side and disconnects the communication (Fig. 2(b)).
Therefore, we conducted a detailed analysis to findout why the receiver fax was disconnecting in thismanner.
2

Practical Field Information about Telecommunication Technologies

12.0

13.0

14.0

15.0

16.0

17.0

18.0

19.0

20.0

21.0

22.0

23.0

Receive

0.2
0.1
0.0

Image signal

TCF

−0.1
−0.2
0.2

Send

0.1
0.0

DCN

CFR

−0.1
−0.2

Fig. 3. Results of analyzing audio file using Audacity.

Table 1. Results of signal analysis.
CFR

Detected signal

Signal transmit time

Approx. 1350 ms

Approx. 1350 ms

Signal frequency

Approx. 1650 Hz

Approx. 1650 Hz

Signal level

Approx. –18 dBm

Approx. –45 dBm

4. Analysis of audio data using Audacity
We extracted RTP packets from captured Ethernet
data on the receive side at the time of failure and analyzed the audio files saved for each call made andreceived using Audacity*1 software. In our analysis,
we found a particular signal that could not be recognized by the G3 facsimile tester (Fig. 3, red-framedbox).
This signal differed from the TCF (training check
function) signal and image signal transmitted by thesender fax, while it had the same signal transmit timeand signal frequency as the CFR (confirmation toreceive) signal transmitted by the receiver fax(Table 1, red-framed box).
The above results suggest that this signal was an
echo*2 of the CFR signal transmitted by the receiver
fax and that it originated in the extension package of
the PBX equipment on the sender side (2-line/4-line
converter), as shown in Fig. 4.
5. Cause of failure
It was thought that a CFR echo of approximately–45 dBm or greater generated in the extension package of the PBX equipment (2-line/4-line converter)
would exceed the receive-level threshold of the3

receiver fax. This echo would consequently be erroneously recognized as a signal from the sender fax,
causing this failure to occur. The signal level of the
CFR echo during normal operation was approximately –70 dBm (Fig. 5).
6. Countermeasures
We considered that the receive-level threshold of
the receiver fax could be raised so that the echo would
not exceed that threshold, or that the transmit level ofthe receiver fax could be lowered so as to reduce theecho and prevent it from being recognized as a valid*1 Audacity: Audio editing software that allows for data editing
while viewing graphs (waveforms/spectra) that visually represent
the content of the audio file. http://www.audacityteam.org/*2 Echo: G3 facsimiles (V.17 and beyond) operate on half-duplex
communications, which means that the transmit-control sectionuses the same frequency band for both send and receive signals.
Consequently, if the echo is large, the echo of the transmit signal
when transmit control switches between send and receive may be
mistaken for a signal transmitted by the other party, giving rise toan anomaly in transmit control.
(Excerpted from CIAJ (Communications and Information Network Association of Japan) standard CES-Q006-1: Guidelines on
VoIP-TA/Facsimile Terminals When Accommodating Facsimile
Terminals via VoIP-TA in IP-PBX, 3.1.1.3 Effects of Echo, Oct.
2007 (in Japanese).)http://www.ciaj.or.jp/gazou/guideline/guide_uns.pdf

NTT Technical Review

Practical Field Information about Telecommunication Technologies

Sender fax

Receiver fax
PBX
Extension
PKG

HGW
Outerline
PKG

Hikari Denwa

SLIC

SLIC

network

Main signal
Echo

2-line/4-line converter
Receive

Hybrid circuit

CFR[4-linesystem][2-line system]
Echo

Send
SLIC: subscriber line interface circuit

Fig. 4. Echo generation at 2-line/4-line converter.

Receive-level
threshold

Sender fax

Receiver fax

Echo (approx. –70 dBm)

Echo (approx. –45 dBm)

Recognized as a signal
giving rise to failure

Fig. 5. Threshold of receive level.

signal.
However, because the receiver fax was a model forwhich the receive-level threshold could not be changed,
we lowered the transmit level in 1-dB increments andfound that lowering it by 2 dB was enough to preventthe reoccurrence of this event. We considered that thiswas because the echo would no longer exceed thereceive-level threshold of the receiver fax at thattransmit level, thereby preventing the echo frombeing mistakenly recognized as a signal from thesender fax.

Vol. 15 No. 2 Feb. 2017

7. Conclusion
In IP network services, devices with analog line or
ISDN interfaces may be used in configurations consisting of gateways and PBX equipment. Solving
problems in such configurations requires a combination of measurement equipment and analysis methods
for each type of interface.
The case study presented here showed how analyzing analog line interface signals and Ethernet data
made it possible to solve a puzzling problem. Goingforward, the Technical Assistance and Support Center
aims to continue its work in solving difficult4Practical Field Information about Telecommunication Technologies

problems through the use of diverse tools and theanalysis of signals and data for a variety of interfaces.

5

NTT Technical Review

Short Reports

Experimental Test of Macroscopic
Realism Problem Using a
Superconducting Flux Qubit
1. Introduction
NTT and the University of Illinois have conducted
an experimental test on the breaking of macroscopic
realism*1 in a superconducting circuit using a flux
qubit*2.
The idea that an observed object exists even before
it is observed is called realism. This is commonly
accepted in the macroscopic world in which we live.
In contrast, in the microscopic world described byquantum mechanics *3, realism is broken *4. Thismeans that a state cannot be determined before it isobserved and is in fact determined by the observation.
If the macroscopic world is also described by quantum mechanics, realism must be broken there. The
question is, can realism be broken in the macroscopic
world, or is there a limitation to the application ofquantum mechanics in the macroscopic world? Thisis one of the biggest unsolved problems since thediscovery of quantum mechanics.
We tested this using a superconducting flux qubitthat had 1012 electrons flowing around it per secondand found that realism was broken in this supercurrent. We demonstrated that quantum mechanics isapplicable on a macroscopic scale in this supercurrent. This contributes significantly to the field offundamental physics and shows that a superconducting flux qubit works as a real quantum device.
This work was published in the online version of
Nature Communications on the 4th of November,2016 (GMT) [1].
2. Background
Even a single electron passing through a double slit
exhibits interference fringes*5. Interference fringes
do not appear if the electron passes through only one
slit. This means that superposition is realized between
the left slit passed state and the right slit passed state.
1

These interference fringes disappear when we obtain
information (by observation) revealing the slit thatthe electron passed through. This means that realism,
as it is commonly accepted in the macroscopic world,
does not hold in the microscopic world described byquantum mechanics. We can expect realism to bebroken in the macroscopic world if this world also
obeys quantum mechanics. The purpose of our work
is to demonstrate the breaking of macroscopic realism, and thus imply that our commonly held belief iswrong (Fig. 1).
3. Experiment
NTT Basic Research Laboratories carried out a test
experiment on breaking macroscopic realism using a
superconducting flux qubit made of aluminum anddemonstrated breaking of the realism of a superconducting flux qubit current state by 84 times the standard deviation. This work demonstrated that quantum
mechanics can be applied on a macroscopic scalewith a large supercurrent and is not simply limited to*1 Realism: The idea that an object exists independent of its observation, for example, “The moon exists even when no one looks at
it.”*2 Superconducting flux qubit: A superconducting circuit constructed from a superconducting loop including Josephson junctions.
By applying a magnetic field with an optimal bias, we can consider this circuit to be a quantum two-level system, with clockwise and anti-clockwise current states.
*3 Quantum mechanics: A set of physical laws that can govern the
behavior of particles and waves at the microscopic level (for example in electrons and atoms). It allows strange behavior such as
quantum superposition and entanglement.
*4 Realism breaking: The idea that the state is determined at (notbefore) the time of the observation. For example, with a quantum
superposition of two states, the state is not determined before its
observation. The observation collapses one of the two states thatmake up the superposition.
*5 Interference fringes: A stripe pattern appearing when a systemcomposed of several superposed waves is measured.

NTT Technical Review

Short Reports

Realism, as commonly understood in the macroscopic world, is denied in the microscopic world described by quantum
mechanics. We tested the breaking of macroscopic realism, which will occur if the macroscopic world also obeys
quantum mechanics.
Macroscopic realism
The moon exists even if no one is looking at it.
Dice pips are fixed without anyone looking at them.

Breaking of macroscopic realism
Quantum dice whose pips are not determined
before looking at them also exist.
Observation

Observation

Readout

Readout

Breaking of microscopic
realism (quantum behavior)e–
We could not say which slit
the electron passed throughwithout observation. (originof quantum computationand communication)

Electronpassing
through double
slit
Observation

Purpose of this study
Test to determine whether macroscopic
realism can be broken.

Fig. 1. Breaking of macroscopic realism.

a microscopic scale.
The experiment was performed by cooling a superconducting qubit to 10 mK. This enables us to prepare qubits in the lowest energy state (ground state:–1) because there is no thermal excitation in this temperature region. We then read out the qubit state after
performing two operations (qubit state rotations) on
the superconducting flux qubit. We compared theresults obtained with and without observation during
these two qubit operations.
We prepared the flux qubit in a coherent superposition of its ground (–1) and excited (+1) states with afirst state operation and measured the difference
between the results with and without observation(main experiment*6). If realism is true, we can expect
the readout result to be independent of the observation because the state is determined before the observation. On the other hand, if realism is broken byquantum superposition, the qubit state will become+1 or –1 as a result of the observation. In our case,differences appeared in the readout results because of
the observation.
Next, we carried out control experiments to confirm
that the observation did not disturb the qubit state(control experiment*7). We prepared +1 or –1 statesby using the first state operation and measured thedifference between the results caused by the exisVol. 15 No. 2 Feb. 2017

tence of the observation. By confirming that this difference is small, we can confirm the non-invasivenessof the observation, which means that our (+1, –1)
control state was not changed by the observation. The
difference from the result of our main experiment waswell beyond that of the control experiments, meaningthat we successfully demonstrated realism breaking
on macroscopic objects such as a current state.
4. Technical features(1)	Measurement method mathematically equivalent to Leggett-Garg inequality*8
To confirm the breaking of realism on a physical*6 Main experiment: This is an experiment designed to confirm thatthe generated superposition state changes into one of +1 or –1
states by observation. It is expected that the results obtained withand without observation show different values, respectively, if aquantum superposition state is realized.
*7 Control experiments: These are experiments undertaken to confirm that the state is not changed by observation when we preparea pure +1 or –1 state. We expect to see sufficient small observation induced changes in these experiments to distinguish changes
in the superposition state.
*8 Leggett-Garg inequality: An inequality obtained by correlating
values measured at several different times. This inequality is satisfied in a system in which realism appears; however, this issometimes broken in the quantum world.

2

Short Reports

system, we first need to demonstrate the breaking of
the condition called the Leggett-Garg inequality. Thisinequality is always satisfied if realism is correct;
however, it can be broken in systems that do not obey
realism, for instance, quantum mechanics. It is difficult to show the breaking of the Leggett-Garg
inequality directly because we have to measure thequbit state at least three times using high fidelity
detection while the qubit maintains its quantum characteristics. These are hard conditions to achieve
experimentally. We used an alternative method that ismathematically equivalent to the Leggett-Garg
inequality and that avoids this detection difficulty.
(2)	Superconducting flux qubit and state observation
To show the breaking of macroscopic realism, weneed to detect small disturbances caused by observing a macroscopic system. A superconducting flux
qubit has two states corresponding to +1 and –1. In
each state, a few hundred nanoamperes of superconducting circulating current flow clockwise and anticlockwise, respectively. These currents correspond to1012 electrons flowing around the loop per second,
and this is a sufficiently macroscopic value to be
detected with a current meter. It is necessary toobserve the qubit current state without disturbing it.

However, quantum non-demolition measurement*9,
which can achieve this, has proved difficult to realize.
We achieved fast and highly accurate quantum nondemolition measurement of a superconducting flux
qubit current state using a Josephson bifurcation
amplifier*10.
5. Future plans
We aim to demonstrate measurements with muchless observation disturbance and to increase the macroscopic nature of the system by using a large supercurrent qubit or an ensemble of superconducting flux
qubits.
Reference[1]

G. C. Knee, K. Kakuyanagi, M.-C. Yeh, Y. Matsuzaki, H. Toida, H.
Yamaguchi, S. Saito, A. J. Leggett, and W. J. Munro, “A Strict Experimental Test of Macroscopic Realism in a Superconducting Flux
Qubit,” Nat. Commun., Vol. 7, 13253, 2016.

For Inquiries
Public Relations,
NTT Science and Core Technology Laboratory
Group
Email: a-info@lab.ntt.co.jp*9 Quantum non-demolition measurement: A measurement thatkeeps the state after measurement unchanged when we prepare
an eigenstate such as an excited state or a ground state.
*10 Josephson bifurcation amplifier: A device for detecting small displacements. We can generate a bistable state in a nonlinear resonator including a Josephson junction by driving it with an optimal microwave. The nonlinear resonator converges to a different
stable state depending on the displacement of the coupled object,
so we can obtain information about displacement. We can readout a superconducting flux qubit state quantum non-destructively.

3

NTT Technical Review

External Awards
IEEE Fellow
Winner: Shinji Matsuo, NTT Device Technology Laboratories
Date: January 1, 2016
Organization: The Institute of Electrical and Electronics Engineers(IEEE)For his contributions to heterogeneous integration of semiconductor lasers.
Best Paper
Winner: Tatsuaki Kimura and Hiroshi Saito, NTT Network Technology Laboratories
Date: November 15, 2016
Organization: The 19th ACM International Conference on Modeling, Analysis and Simulation of Wireless and Mobile Systems(MSWiM ’16)
For “Theoretical Interference Analysis of Intervehicular Communication at Intersection with Power Control.”Published as: T. Kimura and H. Saito, “Theoretical Interference
Analysis of Intervehicular Communication at Intersection with
Power Control,” Proc. of MSWiM ’16, pp. 3–9, Malta, Nov. 2016.
ITU Kaleidoscope 2016 Best Paper Award
Winner: Kazuhide Nakajima, Takashi Matsui, Kotaro Saito, Taiji
Sakamoto, and Noriyuki Araki, NTT Access Network Service Systems Laboratories
Date: November 16, 2016
Organization: International Telecommunication Union (ITU)

For “Space Division Multiplexing Technology: Next Generation
Optical Communication Strategy.”
Published as: K. Nakajima, T. Matsui, K. Saito, T. Sakamoto, and N.
Araki, “Space Division Multiplexing Technology: Next Generation
Optical Communication Strategy,” ITU Kaleidoscope 2016, Bangkok, Thailand, Nov. 2016.
Electrical Science and Engineering Promotion Award
Winner: Yuichi Higucihi, NTT Device Innovation Center; Masaru
Kobayashi and Toru Miura, NTT Advanced Technology Corporation
Date: November 16, 2016
Organization: The Promotion Foundation for Electrical Science andEngineering
For development of a cleaning technique for an optical fiber connector and for diffusion of the optical connector cleaner.
Best Young Presentation Award
Winner: Daisuke Kitayama, NTT Device Technology Laboratories
Date: November 25, 2016
Organization: Symposium on Frontier of Terahertz Science III
For “Metamaterial-based Flat Lens toward Dynamic Control ofTransmissive Waves.”
Published as: D. Kitayama, “Metamaterial-based Flat Lens toward
Dynamic Control of Transmissive Waves,” Symposium on Frontier ofTerahertz Science III, Fukui, Japan, Nov. 2016.

Papers Published in Technical Journals andConference Proceedings
Quantum Algorithms for Finding Constant-sized Subhypergraphs
F. L. Gall, H. Nishimura, and S. Tani
Theoretical Computer Science, Vol. 609, No. 3, pp. 569–582,
January 2016.
We develop a general framework to construct quantum algorithms
that detect if a 3-uniform hypergraph given as input contains a subhypergraph isomorphic to a prespecified constant-sized hypergraph.
This framework is based on the concept of nested quantum walks
recently proposed by Jeffery, Kothari and Magniez (2013) andextends the methodology designed by Lee, Magniez and Santha(2013) for similar problems over graphs. As applications, we obtaina quantum algorithm for finding a 4-clique in a 3-uniform hypergraph1

on n vertices with query complexity O(n1.883) and a quantum algorithm for determining if a ternary operator over a set of size n isassociative with query complexity O(n2.113).

Power of Quantum Computation with Few Clean Qubits
K. Fujii, H. Kobayashi, T. Morimae, H. Nishimura, S. Tamate, and
S. Tani
Proc. of 43rd International Colloquium on Automata, Languages,
and Programming (ICALP 2016), pp. 13:1–13:14, Rome, Italy, July
2016, arXiv:1509.07276 [quant-ph].
This paper investigates the power of polynomial-time quantum

NTT Technical Review

Papers Published in Technical Journals and Conference Proceedings

computation in which only a very limited number of qubits are initially clean in the |0> state, and all the remaining qubits are initiallyin the totally mixed state. No initializations of qubits are allowed during the computation, nor intermediate measurements. The main
results of this paper are unexpectedly strong error-reducible properties of such quantum computations. It is proved that any problem
solvable by a polynomial-time quantum computation with one-sided
bounded error that uses logarithmically many clean qubits can also be
solvable with exponentially small one-sided error using just two
clean qubits, and with polynomially small one-sided error using justone clean qubit. A similar result is proved in the case of two-sided
bounded error.

Optomechanics: Single-photon Frequency Shifting
E. Kuramochi and M. Notomi
Nature Photon, Vol. 10, No. 12, pp. 752–753, December 2016.
A fingertip-sized on-chip optomechanical device offers a controllable way to shift the frequency of single photons in the telecom band
while preserving their quantum information.

Quantum Query Complexity of Almost All Functions with
Fixed On-set Size
A. Ambainis, K. Iwama, M. Nakanishi, H. Nishimura, R. Raymond, S. Tani, and S. Yamashita
Computational Complexity, Vol. 25, No. 4, pp. 723–735, December 2016.
This paper considers the quantum query complexity of almost allfunctions in the set FN,M of N-variable Boolean functions with on-set
size M(1 ≤ M ≤ 2N /2), where the on-set size is the number of inputs
on which the function is true. The main result is that, for all functions
in FN,M except its polynomially small fraction, the quantum querylog M+ N for a constant c > 0. This
complexity is Θ
c+log N−log log M
is quite different from the quantum query complexity of the hardest
function in FN,M:
log M+ N . In contrast, almost all functions inΘ N
c+log N−log log M
FN,M have the same randomized query complexity Θ(N) as the hardest
one, up to a constant factor.

(

(

)

)

A Fast Exact Quantum Algorithm for Solitude Verification
S. TaniarXiv:1612.05317 [quant-ph], December 2016.
Solitude verification is arguably one of the simplest fundamental
problems in distributed computing, where the goal is to verify that
there is a unique contender in a network. This paper devises a quantum algorithm that exactly solves the problem on an anonymous
network, which is known as a network model with minimal assumptions [Angluin, STOC’80]. The algorithm runs in O(N) rounds ifevery party initially has the common knowledge of an upper bound N
on the number of parties. This implies that all solvable problems canbe solved in O(N) rounds on average without error (i.e., with zerosided error) on the network. As a generalization, a quantum algorithm
that works in O(N log2 (max{k, 2})) rounds is obtained for the problem of exactly computing any symmetric Boolean function, over n
distributed input bits, which is constant over all the n bits whose sum
is larger than k for k ∈ {0, 1,…,N − 1}. All these algorithms workwith the bit complexities bounded by a polynomial in N.

Vol. 15 No. 2 Feb. 2017

Active Manual Movement Improves Directional Perceptionof Illusory Force
T. Amemiya and H. Gomi
IEEE Transactions on Haptics, Vol. 9, No. 4, pp. 465–473, December 2016.
Active touch sensing is known to facilitate the discrimination orrecognition of the spatial properties of an object from the movementof tactile sensors on the skin and by integrating proprioceptive feedback about hand positions or motor commands related to ongoing
hand movements. On the other hand, several studies have reported
that tactile processing is suppressed by hand movement.
Thus, it is unclear whether or not the active exploration of force
direction by using hand or arm movement improves the perception of
the force direction. Here, we show that active manual movement inboth the rotational and translational directions enhances the precise
perception of the force direction. To make it possible to move a handin space without any physical constraints, we have adopted a methodof inducing the sensation of illusory force by asymmetric vibration.
We found that the precision of the perceived force direction was significantly better when the shoulder is rotated medially and laterally.
We also found that directional errors supplied by the motor responseof the perceived force were smaller than those resulting from perceptual judgments between visual and haptic directional stimuli. These
results demonstrate that active manual movement boosts the precision of the perceived direction of an illusory force.

Tactile Apparent Motion on the Torso Modulates Perceived Forward Self-motion Velocity
T. Amemiya, K. Hirota, and Y. Ikei
IEEE Transactions on Haptics, Vol. 9, No. 4, pp. 474–482, December 2016.
The present study investigated whether a tactile flow created by amatrix of vibrators in a seat pan simultaneously presented with an
optical flow in peripheral vision enhances the perceived forward
velocity of self-motion. A brief tactile motion stimulus consisted offour successive rows of vibration, and the interstimulus onset
between the tactile rows was varied to change the velocity of thetactile motion. The results show that the forward velocity of selfmotion is significantly overestimated for rapid tactile flows andunderestimated for slow ones, compared with optical flow alone or
non-motion vibrotactile stimulation conditions. In addition, the effectwith a temporal tactile rhythm without changing the stimulus location was smaller than that with spatiotemporal tactile motion, with
the interstimulus onset interval to elicit a clear sensation of tactile
apparent motion. These findings suggest that spatiotemporal tactile
motion is effective in inducing a change in the perceived forward
velocity of self-motion.

Sanshool on the Fingertip Interferes with Vibration Detection in a Rapidly-adapting (RA) Tactile Channel
S. Kuroki, N. Hagura, S. Nishida, P. Haggard, and J. Watanabe
PLOS ONE, Vol. 11, No. 12, e0165842, December 2016.
An Asian spice, Szechuan pepper (sanshool), is well known for the
tingling sensation it induces on the mouth and on the lips. Electrophysiological studies have revealed that its active ingredient can
induce firing of mechanoreceptor fibres that typically respond tomechanical vibration. Moreover, a human behavioral study hasreported that the perceived frequency of sanshool-induced tingling
matches with the preferred frequency range of the tactile rapidly2Papers Published in Technical Journals and Conference Proceedings

adapting (RA) channel, suggesting the contribution of sanshoolinduced RA channel firing to its unique perceptual experience. However, since the RA channel may not be the only channel activated bysanshool, there could be a possibility that the sanshool tingling percept may be caused in whole or in part by other sensory channels.
Here, by using a perceptual interference paradigm, we show that thesanshool-induced RA input indeed contributes to the human tactile
processing. The absolute detection thresholds for vibrotactile input
were measured with and without sanshool application on the fingertip. Sanshool significantly impaired detection of vibrations at 30 Hz(RA channel dominant frequency), but did not impair detection ofhigher frequency vibrations at 240 Hz (Pacinian-corpuscle (PC)channel dominant frequency) or lower frequency vibrations at 1 Hz
(slowly adapting 1 (SA1) channel dominant frequency). These results
show that the sanshool induces a peripheral RA channel activationthat is relevant for tactile perception. This anomalous activation of
RA channels may contribute to the unique tingling experience ofsanshool.

Manipulating and Trapping Light with Photonic Crystals
from Fundamental Studies to Applications
E. Kuramochi
Journal of Materials Chemistry C, Vol. 4, No. 47, pp. 11032–
11049, December 2016.
Photonic crystal technology, which was initially proposed as a way
to realize nanoscale nanocavities and nanowaveguides, is now finding applications as a surface interface layer technology for lightemitting diodes with high brightness and solar cells with high conversion efficiency. On the other hand, nanocavities, which can efficiently confine light in an ultrasmall footprint with significantly
enhanced photon lifetime, have greatly contributed to cavity quantum
electrodynamics studies. Such nanocavities have also realized prototypes of ultralow-power functional devices and high-density integrated photonic circuits. In this review article, I focus on planar andtwo-dimensional slab photonic crystal and related structures, whichhave played major roles in both fundamental studies and device
applications.

Mobile Silk Fibroin Electrode for Manipulation and Electrical Stimulation of Adherent Cells
T. Teshima, H. Nakashima, N. Kasai, S. Sasaki, A. Tanaka, S.
Tsukada, and K. Sumitomo
Advanced Functional Materials, Vol. 26, No. 45, pp. 8185–8193,
December 2016.
Microfabricated mobile electrodes, nanopallets, designed to provide adherent cells with electrical stimulation are reported. Nanopallets composed of a cross-linked silk fibroin hydrogel matrix incorporated with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate(PEDOT:PSS) are used. The silk fibroin composite is characterized
not only by mechanical and electrical conductive properties, but also
by its optical transparency in both the visible and ultraviolet regions,and by its biocompatibility with adherent cells. It is demonstrated thatthe adherent cells, including normal cell-lined cells and primaryneuronal cells, loaded on the nanopallets can be manipulated whilefaithfully retaining their adhesive properties. By applying voltages
via the nanopallets, the voltage-dependent calcium channels
expressed in the cells are selectively stimulated, and this is confirmed
by using confocal fluorescent microscopy during manipulation andperforming multiangle observations. These features are attributed toboth the mobile operation of the transparent nanopallets, and the ability to simultaneously measure electrical signals and perform fluorescent observations.

MSF: Architecture to Leverage Commodity Switches into
Carrier-grade Networking
H. Yoshioka
Carrier Network Virtualization 2016, Palo Alto, CA, USA, December 2016.
The vision, development status, and innovation roadmap of NTT’s
NetroSphere concept and MSF (Multi-Service Fabric) architecture
were explained.

3

Collective First-person Vision for Automatic Gaze Analysis in Multiparty Conversations
S. Kumano, K. Otsuka, R. Ishii, and J. Yamato
IEEE Transactions on Multimedia, Vol. 19, No. 1, pp. 107–122,
January 2017.
This paper targets small- to medium-sized-group face-to-face conversations where each person wears a dual-view camera, consistingof inward- and outward-looking cameras, and presents an almost
fully automatic but accurate off-line gaze analysis framework that
does not require users to perform any calibration steps. Our collective
first-person vision framework, where captured audio-visual signals
are gathered and processed in a centralized system, jointly undertakes
the fundamental functions required for group gaze analysis, including speaker detection, face tracking, and gaze tracking. Of particularnote is our self-calibration of gaze trackers by exploiting a generalconversation rule, namely that listeners are likely to look at the
speaker. From the rough conversational prior knowledge, our system
visualizes fine-grained participants’ gaze behavior as a gaze-centeredheat map. An experiment achieves a mean absolute error of 2.8
degrees in gaze tracking.

NTT Technical Review