FEATURE

Wireless Communication Technologies for
the New Services Toward 5G and Beyond
1

Evolving Forms of Wireless Communication
Connect People and Devices
Kiyoshi HAMAGUCHI / Fumihide KOJIMA

4

A Roadside Infrastructure for the Future ITS…
Smart wireless traffic mirror
Changwoo PYO

6

Promoting Industrial Collaboration to Achieve Stable Operationof Wireless Communications in Factories
Satoko ITAYA / Fumiko OHORI

8

Wireless Systems Supporting the Safe Operation of
Unmanned Aircraft Systems
Expanding UAS operations to fly further, higher, more often, and fora wider range of purposes
Fumie ONO / Lin SHAN / Toshinori KAGAWA

10

Challenges to Use RF Signals in Underwater
to Open a New Field
Takashi MATSUDATOPICS
Cover photo:
A base station antenna being installed on
the roof of the Yokosuka Research Park
(YRP) No. 1 Building for field experiments.
The Wireless Systems Laboratory has been
researching and developing the STABLE
wireless access technology, which is capable of simultaneously connecting numerous devices wirelessly and significantly
reducing communication delays in anticipation of the widespread use of remotely
controlled robots and drones.
Upper-left photo:
A laboratory in the YRP No. 1 Building.
NICT researchers are developing a newwireless access technology using stateof-the-art measurement and analysis instruments.

12

Toshinori KAGAWA
Creating a Wireless Network to Facilitate
the Widespread Use of Robot

13

Awards

NICT’s Challengers File 6

Evolving Forms of WirelessCommunication Connect People
and Devices
Wireless Networks Research Center

Kiyoshi HAMAGUCHI (left)
Director General
Wireless Networks Research Center
After completing his graduate studies, HAMAGUCHI
worked for a private company before joining the Ministry of Posts and Telecommunications’ Communications
Research Laboratory (since renamed NICT) in 1993. Heassumed his current position in 2017. He has carried out
R&D related to communications and radar and participated in ITU-R standardization. Ph.D. (Engineering).

Wireless communications have a long development history. Advances indigital and networking technologies are expected to push the evolution of
wireless network systems forward.
Changes in wireless communications technology have been accelerating inrecent years, driven by the popularization of portable communications devices, such as mobile phones, and the advent of fifth-generation cellular network
technology (5G) and the internet of things (IoT). How are these changes shaping
the visions, R&D policies and future direction of the Wireless Networks ResearchCenter? We asked Kiyoshi HAMAGUCHI (Director General of the Wireless Networks Research Center) and Fumihide KOJIMA (Director of the Wireless Systems
Laboratory); both of them are based at the Yokosuka Research Park (YRP).

Fumihide KOJIMA (right)■ Current status of wireless systems

disasters reminded the public that mobile
phones are a vital lifeline. It was also a big
wake-up call for researchers: wireless communications technologies are indispensable
not only for enjoying a higher quality of life
but also in ensuring public safety.
A new issue has emerged, however, as
the number of wireless communications users has increased: a looming radio frequency
shortage. This issue necessitated the development of new technologies enabling larger-capacity, higher-speed communications
using limited radio frequency resources. One
approach is to use radio waves with very highfrequencies, which allow transmission rates
to increase in the millimeter wave band (30–300 GHz) and terahertz band (0.3–3 THz).
The increasing number of wireless devices
has also led to radio interference concerns.
New technologies are needed to reduce or
eliminate interference even when data traffic
is high to ensure sound communications. The
development of these technologies is expected to be further expedited by the introduction——First of all, could you describe the
Wireless Networks Research Center?
HAMAGUCHI: The mission of the Wireless
Networks Research Center is to conduct research on advanced wireless communications
technologies to increase the security andquality of public communications services.
The Center consists of the Wireless Systems
Laboratory—whose primary research focus
is terrestrial wireless communications technologies—and the Space Communications
Laboratory, which researches space-based
communications technologies.
The Wireless Systems Laboratory isbased at the YRP while the Space Communication Systems Laboratory operates at both
NICT headquarters in Koganei, Tokyo andat the Kashima Space Technology Center in
Kashima, Ibaraki Prefecture.
——NICT has been researching wirelesscommunications technology for many
years. Why are wireless systems attracting
so much attention today?
HAMAGUCHI: It is difficult to find communications systems in our communities that
operate by means other than radio waves.
The penetration rate of radio wave communications systems is over 130% based on thenumber of mobile phone users, indicatingwidespread public use of diverse wirelesscommunications technologies, such as WiFi, RFID＊1 and keyless entry systems. Demand for radio waves is expected to further
increase as anticipated new technologies are
deployed, such as 5G, IoT, and connectedcars. The popularity of wireless systems is
expected to undergo explosive growth.
When the Great Hanshin-Awaji Earthquake occurred in 1995, the mobile phone
and PHS device penetration rate was lessthan 10%. This had increased significantly
to more than 95% by the time of the Great
East Japan Earthquake in 2011. These severe

Director of the Wireless Systems Laboratory
Wireless Networks Research Center
KOJIMA joined the Ministry of Posts and Telecommunications’ Communications Research Laboratory (since renamed NICT) in 1999 where he helped standardize andcarry out R&D related to intelligent transport system(ITS), ad-hoc networks for disaster management andsmart utility networks (SUNs), among other subjects. He
assumed his current position in 2016. He has been working on R&D related to next-generation wireless communications (e.g., 5G/B5G) and the social implementationof these technologies. Ph.D. (Engineering).

NICT NEWS 2019 No.5

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Evolving Forms of Wireless Communication
Connect People and Devices
of 5G and IoT.

■ Responses to 5G——What is your approach to the development of 5G products?
KOJIMA: Generally speaking, communication systems are first subjected to international standardization. Stable products are thenproduced based on the established standards.
Standardization organizations include IEEE
802＊2 and 3GPP＊3. We intend to actively
participate in the activities of these organizations and apply their standards to NICT-developed products.
5G technology has outstanding potential, including ultrahigh speed transmission,
significantly reduced communication delay
and the ability to connect numerous devices
simultaneously. However, these capabilities
are not all simultaneously available. Different IT businesses are likely to gradually
integrate specific 5G capabilities into theirservices. For example, according to one estimate, simultaneous device connections willreach the level of one million connected terminal devices per km2. When 5G technology
is introduced, this capability is predicted tobe less important for many services than other capabilities. However, we have assumed
that all 5G capabilities will be widely andeffectively utilized and smoothly integrated
into various services and have been actively
engaged in 5G-related research to develop
technologies that will enable the simultaneous connection of a huge number of devices. Last year, we conducted experiments inwhich we succeeded in simultaneously connecting 20,000 terminal devices to a single
base station and released the results to themass media. In addition, our lab developed aso-called STABLE technology to enable thesimultaneous connection of numerous devices while minimizing communication delay.
We confirmed that this technology was able
to increase frequency utilization efficiency
by 250%.
——Has progress been made in reducing

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NICT NEWS 2019 No.5

high-frequency waves—such as millimeterwaves—to practical use?
KOJIMA: 5G technology allows use of the
28 GHz band—close to the millimeter wave
band—and even higher frequency bands insome countries. Because high-frequency radio waves have a strong tendency to travelin straight lines, like light, they attenuate
greatly when obstacles interrupt their paths.
To effectively leverage 5G capabilities,
technologies that can stably handle high-frequency radio waves are needed. In addition,
high-frequency radio waves can travel only
limited distances. NICT has been studying
a beamforming technology which allows atransmitter to direct a radio-wave beam to amoving terminal device and massive-element
antenna systems (massive MIMO＊4) to address this issue and enable this technology tofunction properly.

■ Coordination with mobile carriers—— How will NICT and the mobile carriers share roles?
KOJIMA: Because high-frequency radio
waves, such as those in the millimeter wave
band, may travel no more than several hundred meters, the effective service range of abase station will be very limited. This would
necessitate the installation of a huge numberof base stations for nationwide communication services. As this is financially impractical, a more practical approach would be toconcentrate base stations in high-demandareas.
To put this strategy into practice, basestations with large and small service ranges
will need to be coordinated. Technologies
for achieving this coordination are therefore
another key focus of our research. When 5G
technology becomes available, its exploitation may not be limited to the major existing mobile network operators; new operators
may also leverage it to start small cell network services. These new entrants may increase their user bases by attracting conventional LTE (4G) users. If this scenario comesto pass, short-range services will be available
even if major operators do not take the initiative in installing short-range base stations
across large areas.
We anticipate that 4G and 5G technologies will coexist for some time during thetechnological transition. We have therefore
been investigating technologies capable ofenhancing coordination between 4G and 5Gbase stations.

■Extreme communication
environments——What types of projects have been
carried out at the Wireless Networks Research Center?
KOJIMA: We have three major R&D categories: "wireless network management technologies," which is an effort to develop advanced base station infrastructure, "wirelessnetwork customization technologies," whose
objective is to enhance coordination between
wireless terminal devices, and "wireless network technologies with enhanced reliability," which has the goal of expanding therange of applications for wireless systems
and increasing their reliability.
HAMAGUCHI: The management technologies are used to coordinate base station cells,
minimize delay in 5G communications andenable the simultaneous connection of many
devices. The customization technologies include wireless grid technologies that enablemachine-to-machine and device-to-device
communications and technologies that are
being used to develop wireless communications environments in factories. Finally, thetechnologies with enhanced reliability include drones equipped with wireless repeaters that can be used in environments in which
wireless communications infrastructure isunavailable (e.g., disaster-affected areas)
and wireless technologies compatible withextreme environments considered unsuitable
for radio wave use.
——In what scientific fields was it mostchallenging to apply radio waves?

Demonstration of SUN radio devices controlling water levels intanks projected for use in agriculture. These energy-efficientdevices are compatible with IoT technology.

Prototype of an autonomous micro-cell base station compatible with the millimeter wave band. Itsability to coordinate with and control a 5G system was evaluated.

KOJIMA: One example is the application ofradio communications to drug delivery systems. The technology allows the precise location of a small drug capsule in the patient's
body to be remotely detected after ingestion.
Some medical scientists are interested
in accurately tracking the paths of ingested
capsules in the body in order to find waysof delivering drugs to a precise target site.
In this technology, a mechanism similar toan RFID device is incorporated into a drug
capsule and its location in the body is determined using several external antennas. The
electrical permittivity (a measurement of radio wave transmissivity) of different parts of
the human body (e.g., skin, internal organs
and bone) varies. For this reason, the development of this new technology has been very
challenging, but the effort has been rewarding for me.
HAMAGUCHI: We are also carrying out undersea wireless communications research.
Although the underwater marine environment is largely incompatible with radio wave
transmission, close-range transmission is
feasible. In collaboration with JAMSTEC(Japan Agency for Marine-Earth Science andTechnology), we have achieved short-range
transmission of radio waves in several MHz
bands using modified antenna structures.
This technology can be used to greatly increase the mobility of undersea exploration
machinery (e.g., robots) by allowing it to bedisconnected from a "lifeline" cable for more
flexible operations within areas of up to several meters.

■ Strengths of the YRP and future
prospects for 6G—— What unique research environments
are offered at the YRP?
HAMAGUCHI: The YRP opened in October
1997 as a radio wave communications R&D
center and NICT has since established its research base there. The YRP hosts many research facilities and laboratories establishedby companies and universities from all overJapan and overseas at which a wide varietyof research, from basic to leading-edge, hasbeen conducted.
NICT has been jointly carrying out research with these companies and universities.
It also hosts the annual "Wireless Technology Park" (WTP) event around May—one
of Japan's largest wireless communications
technology events for professionals—in collaboration with the YRP R&D Promotion
Committee and the YRP Academia Collaboration Network.
Moreover, NICT and the YRP R&D Promotion Committee cohost the annual International Symposium on Wireless Personal
Multimedia Communications (WPMC) atvarious locations around the world to help
promote the advancement of wireless communications technologies globally.
—— What are the future prospects ofwireless research?
KOJIMA: We carry out R&D projects basedon medium- to long-term plans formulated
by NICT every five years. The next five-yearplan will be issued in 2021. Previous patterns
predict that generational changes occur incommunications technology every 10 years.
Assuming that 6G technology enters service
in 2030 based on this pattern, we plan toRadio anechoic chamber at the YRP Center No. 1 Building. Thischamber is isolated from external radio waves and prevents internal radio waves from escaping, thereby enabling unbiased
radio wave transmission experiments.

identify issues associated with 5G technology and discuss the conceivable demand for
6G technology during the implementation of
the next medium-to-long-term plan.
As a national research institute, we havea responsibility to use our R&D results forthe benefit of society and private companies.
Accordingly, I hope to create technologies
valuable to the Japanese people.
HAMAGUCHI: My ambition is to develop
an ultimate wireless communications systemcapable of bringing new value to society bysatisfying users' diverse needs, increasing energy efficiency, strengthening security, minimizing radio wave interference and raising
the quality of wireless communications tothat of wired communications regardless oftime and location.
I believe that the YRP is Japan's premier
hub for radio wave communications research. Because the next-generation 6G wireless communications technology is likely toemerge in 10 years, I would like to prepare
for it by striving to develop world-leading,innovative wireless communications technologies.
＊1 RFID (Radio Frequency IDentifier): mechanisms by whichdata is communicated via radio waves between radio tags
containing ID information and radio tag readers. This technology has been in practical use in RF tags and non-contact IC cards.
＊2 IEEE (Institute of Electrical and Electronics Engineers) 802
committee＊3 3GPP (3rd Generation Partnership Project): international
standardization project to discuss and develop standards
and specifications for mobile communications systems,
such as mobile phones＊4 Massive MIMO (Massive Multiple Input Multiple Output)

NICT NEWS 2019 No.5

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A Roadside Infrastructure for the Future ITS…
Smart wireless traffic mirror

ntersections without traffic lights
are often associated with high automobile accident risks. Intersections at
which fences, buildings and stopped vehicles obstruct drivers’ vision are particularly
dangerous. To minimize these risks, wehave developed a “smart wireless traffic
mirror.” When mounted on a roadside mirror pole at an intersection, this system iscapable of collecting local traffic data (i.e.,the movement of vehicles and pedestrians
and the presence of obstacles in the vicinity of the intersection) using its sensors,
wirelessly transmitting the data to a serverwhere it is integrated into a database calleda “dynamic map” and delivering local traffic
information to nearby drivers and pedestrians, allowing them to view the movementof other vehicles and pedestrians on a map,
thereby reducing traffic accident risks in

I

Changwoo PYO
Senior Researcher
Wireless System Laboratory
Wireless Networks Research Center
After graduate school, he entered NICT
in 2005. He is engaged in research on
media access control such as WirelessCommunications and Networks, Millimeter Wave Communications, Cognitive
Wireless Communications, and Broadband Wireless Communications in TV
whitespace. Ph.D. (Engineering).

the vicinity of intersections. In addition, thissystem may serve as vital roadside infrastructure capable of assisting in the operation of autonomous vehicles, a new technology anticipated to be put into practicein the near future.

■ Efforts to develop smart mobility
technologies
The aging of the Japanese population is
generating strong demand for smart mobility
technologies, such as autonomous vehicles,
as they may promote greater independence
for elderly people and encourage them tomore actively participate in social events. Remotely controlled vehicles—another smart
mobility technology—are likewise being
pursued in the hope of compensating for labor shortages as Japan’s population shrinks.

Figure 1 Mechanisms and composition of the smart wireless traffic mirror
A. Four-layer dynamic map (source: “Review of study group focused on the realization of a connected car society” released by the Ministry of Internal Affairs and Communications on August 4, 2017). B. Intersection with no traffic light and poor visibility which was usedin our simulation studies. C. Smart wireless traffic mirror. D. Traffic information in the vicinity of the intersection displayed on a map.

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R&D efforts are seeking to increase the reliability and precision of smart mobility technologies by effectively using informationcollected by a variety of sensors, including
those installed in vehicles, and integrating
information and communications technology(ICT).
To put the smart mobility concept into
practice, new technologies need to be developed enabling the continuous collection andanalysis of traffic data, integration of thisdata into a dynamic map and efficient delivery of the final traffic data to relevant users.
A dynamic map—the integration of a varietyof road-related information—is composedof four layers that are updated at different
intervals (Figure 1A): a static layer updated
daily containing information on road surfaces, traffic lanes and roadside structures, etc.;
a semi-static layer updated hourly containing
information on traffic restrictions and road
construction, etc.; a semi-dynamic layer updated minute-by-minute containing information on traffic accidents and congestion, etc.;
and a dynamic layer updated continuously
containing information on the movement ofvehicles and pedestrians and traffic light status, etc.
Most researchers have been focusing on
ways of enabling individual autonomousvehicles to update traffic information on a
dynamic map. In this method, a traveling vehicle collects traffic information (e.g., accidents, congestion and traffic restrictions) using onboard sensors and updates its dynamic
map via wireless communications. However,these sensors may be ineffective when a vehicle approaches curves and intersections associated with frequent accidents due to poor
visibility. Onboard sensors are also unable todetect traffic restrictions and obstacles that

may exist beyond their range. These undetected events and objects cannot be incorporated into the dynamic map.
This problem may be effectively solved
by using an alternative map updating methodthat involves roadside sensors, such as cameras and radar. In this article, I describe thesmart wireless traffic mirror, a system capable of processing and transmitting traffic datacollected by roadside sensor arrays.

■ Smart wireless traffic mirror
visualizes events/objects beyond
the range of a vehicle’s onboard
sensors
When deployed in low-to-zero visibility
locations, such as the intersection shown in
Figure 1B, a smart wireless traffic mirror iscapable of detecting a variety of events (e.g.,
the presence and movement of vehicles andpedestrians, and road construction) and updating a vehicle’s dynamic map with the information it collects. In addition, this system
can wirelessly deliver local traffic information to nearby drivers in a timely manner,
allowing them to foresee traffic situations
beyond the range of their perceptions. Thus,
this system is a vital element of roadside infrastructure that can make road traffic safer.
Figure 1C shows a smart wireless traffic
mirror and its components:
・cameras capable of capturing images of all
objects on the road;・object detectors capable of identifying individual objects in captured images using
machine learning; and・a wireless communications device thattransmits data on identified objects.
Data is sent to and compiled on an edge
server. It is then subjected to integration

processing and used to determine traffic conditions. The processed data is ultimately incorporated into an updated dynamic map. In
simulation studies using a YRP testbed, we
deployed three smart wireless traffic mirrors
and allowed them to cover 40 meters of thethree roads extending from a T-intersection(Figure 1D). These three systems successfully tracked vehicle movement in real time,
captured images of it and determined its position.
Vehicles that received traffic informationcollected and transmitted by a smart wirelesstraffic mirror were able to display it on theirmonitors (Figure 2). These tests demonstrated that the system works effectively. Figure
2A shows an in-vehicle monitor indicating
the presence of a vehicle beyond the rightcorner of the intersection which would ordinarily not be visible to the driver. In Figure
2B, a vehicle crossing the intersection fromthe right can be recognized both by the driver and by reference to the traffic information
displayed on the monitor.

■ Future prospects
The deployment of smart wireless traffic
mirrors may reduce the risks of traffic accidents in the vicinity of intersections by delivering local traffic information to nearby
drivers and pedestrians. 5G mobile communications systems are expected to play a vitalrole in the operation of autonomous vehicles.
By coordinating this technology with 5G systems, it may serve as an important element ofroadside infrastructure capable of enhancing
the reliability and precision of autonomousvehicle operations in the near future.

Figure 2 Real-time local traffic information sent from the smart wireless traffic mirror to a nearby vehicle

NICT NEWS 2019 No.5

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Promoting Industrial Collaboration
to Achieve Stable Operation ofWireless Communications in Factories
he manufacturing sector has faced
increasing demands to expedite
its product development cycles in recent
years. In response, manufacturers are becoming interested in introducing wirelesscommunications at their factories. To address this subject, the National Institute ofInformation and Communications Technology (NICT) launched a Flexible Factory
Project in 2015 with two objectives: coordinating the wide variety of wireless systems
installed within factories and ensuring thatthey operate safely. During this project, wehave been collaborating with many manufacturers across a variety of industries tosurvey the wireless environments found inactively operating factories. In this article,
we describe a simulator—which we are developing based on survey results obtained
during this project—capable of estimating the relationship between a factory's
productivity and the quality of its wirelesscommunications.

T

Satoko ITAYA
Senior Researcher
Wireless System Laboratory
Wireless Networks Research Center
After receiving the Ph.D. degree in 2002,
she joined Advanced Telecommunications Research Laboratory InstituteInternational (ATR) from 2002 to 2007.
She worked in NEC Central ResearchLaboratories from 2008 to 2013. Since
2014, she is a senior researcher at the
Smart Wireless Laboratory of NICT. Her
research interests include complex systems, networking, communications,data analytics, modeling, and applications. Ph.D. (Science).

■ BackgroundSome factories need to make frequentchanges to their production lines withoutcompromising productivity, making flexible
production line design important. Wirelesscommunications play a vital role in achiev-

ing these objectives. When a factory's mobile
equipment (e.g., automated guided vehicles (AGVs), lifting equipment and stacker
cranes) uses wireless communications, thequality of these communications may impact
productivity. Special care must therefore be
exercised when introducing and operating
wireless communications. An increasing
number of manufacturers are showing interest in the development of visualization technologies and simulators, etc. that can be used
to predict the performance of wireless communications in their facilities.

■ Scenarios for using wirelesscommunications in factories
As part of the Flexible Factory Project,
we have been surveying the wireless environments in factories, interviewing factory
workers, carrying out academic research,
preparing reports on the varied use of wireless communications in factories based on
the information gathered and publishingthese reports as white papers. The white papers describe the following four scenariosthat represent typical usage of wireless communications.＊1(1) Metalworking factories
Various machine tools are arranged on afactory floor and materials and manufactured

Fumiko OHORI
Researcher
Wireless System Laboratory
Wireless Networks Research Center
After earning a master's degree in computer science, she joined the KOZOKEIKAKU ENGINEERING Inc. in 2010.
Since October 2017, she is a researcher
at the Smart Wireless Laboratory of NICT
and aims to solve real problems for stable operation of wireless communications in the manufacturing sites.
Figure 1 Conceptual image of wireless communications within a logistics warehouse

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products are handled in specific parts of a
facility. It is important to monitor machines
when they are in operation, take accident
prevention measures and maintain machine
tools properly. Many machine tools we surveyed were old (i.e., 20 to 30 years old) andequipped with aftermarket sensors. Many
factories expressed interest in introducing
wireless communications to gather data fromthese sensors.
(2) Mechanical assembly factories
Many factories in this category havedeveloped systems capable of monitoring
assembly by collecting data on the qualityof each process, analyzing it and providing
feedback. Many of these factories expressedinterest in using wireless communications tomanage the operation of the AGVs they use
to move components between different assembly processes.
(3) Elevated and high temperature work
sites
Certain types of factories (e.g., chemicaland steel plants) are associated with extremely hot and/or humid working environments
and/or risks of collision and falling. It is important to monitor personnel working underthese conditions using vital sensors, observation cameras and other tools. In addition,
wireless communications-based data gathering is necessary to monitor workers who
move between different locations.
(4) Logistics warehouses
Automated vertical storage and retrieval
systems (e.g., stacker cranes) are common-

Figure 2 Five-layer model used to evaluate a manufacturing facility’s wireless communications and productivity

ly used in these facilities to increase space
use efficiency. Large warehouses are often
equipped with multiple orderly arrangementsof racks, each 30 m in height and more than
100 m in width, separated by several-meter
gaps. Operating stacker cranes in a large
warehouse using wired communications requires adequate cables and properly installedwiring. Introducing wireless communications may lower warehouse operating costsby eliminating the need for cables and reducing maintenance costs (Figure 1).

■ Development of simulators
suitable for on-site use
Wireless communications are expected to
be useful in large automated storage systems.
Three-dimensional simulators are an effective tool for simulating the vertical and horizontal movement of manufacturing equipment used in these facilities and determining
optimum ways of maintaining high-quality
communications with these pieces of moving equipment. Many of the existing wirelesscommunications simulators, however, only
perform radio propagation simulations andare difficult for manufacturing facility workers to use because these workers usually lackadequate knowledge on radio communications. In addition, three-dimensional simulations require significantly greater amounts ofcomputing time than two-dimensional simulations. For these reasons, simulations ofwireless system operations in manufacturing
facilities had been difficult. Moreover, existing wireless communications simulators are
ineffective in determining the relationshipbetween facility productivity and wirelesscommunications quality, and are therefore
inadequate for identifying factors influencing
productivity and proper ways of improving
wireless environments. To address these issues, NICT has developed a simulator capable of generating a five-layer model that canbe used to evaluate wireless communications
and the productivity of manufacturing facilities (Figure 2). The simulator is able toperform computations at reasonably realistic speeds even when used at manufacturing
facilities. We achieved this by allowing thesimulator to describe the wireless environment in terms of a probability model. We are
currently carrying out R&D to enable thissimulator to perform mapping, computationand visualization in three dimensions by integrating positioning data collected for theFlexible Factory Project into the simulator(Figure 3). Our R&D is progressing with thehelp of feedback received from manufacturing facility workers.

■ Future prospects
NICT has proposed the SRF WirelessPlatform vision＊2 based on the concept ofenabling coordination between a wide variety
of wireless systems within the same facility
to promote the stable and efficient operationof industrial systems. Two of the privatecompanies participating in the Flexible Factory Project are particularly committed tothis vision, and in July 2017 they established
the Flexible Factory Partnership Alliance(FFPA), a non-profit organization, to put it
into practice. On June 3, 2019, the FFPA received the "Info-Communications Promotion
Month" award for the 2019 fiscal year from
the Ministry of Internal Affairs and Communications (Figure 4) in recognition of the
project and the steady collaboration between
alliance members. This award encouraged
us to work harder, and we hope to continue
making progress on the development of awireless platform that can be operated stably
by manufacturing facility workers.

Figure 4 From left to right: FFPA Director Akihiro
AMAGAI (Sanritz Automation Co, Ltd.), FFPA Director
Masahiro IKUMO (OMRON Corporation), FFPA ViceChair Satoko ITAYA (NICT) and FFPA Secretary-General
Hajime KOTO (NICT)

assembly parts(a) Overall view(b) Side view
Figure 3 Snapshots of a multi-level warehouse generated by the three-dimensional simulator under development by NICT

＊1 http://www2.nict.go.jp/wireless/ffpj-wp.html＊2 SRF (Smart Resource Flow): A system engineering strategy
for managing resources (e.g., human resources, facilities,
equipment, materials, energy, and communications) using
multilayer system analysis to achieve optimal performance

NICT NEWS 2019 No.5

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Wireless Systems Supporting the Safe Operationof Unmanned Aircraft Systems
Expanding UAS operations to fly further, higher,
more often, and for a wider range of purposes
great deal of interest exists in ex-

A panding the capabilities of un-

From the left: Lin SHAN, Fumie ONO, Toshinori
KAGAWA

Fumie ONO
Senior Researcher
Wireless Systems Laboratory
Wireless Networks Research Center
She joined NICT in 2012. She is engaged
in the research on wireless communication system using Unmanned Aircraft
System(UAS), and wireless system for
UAS. Ph.D. (Engineering).

Lin SHAN
Researcher
Wireless Systems Laboratory
Wireless Networks Research CenterHe joined NICT in 2013. His researchinterests include D2D communication,
multiuser-MIMO scheduling, cooperative relaying, and wireless system for
Unmanned Aircraft System (UAS). He
received the IEICE RCS Active ResearchAward and the IEEE VTS Japan Young
Researcher’s Encouragement Award in
2011, and the IEICE Best Paper Award in
2013, respectively. Ph.D. (Informatics).

manned aircraft systems (UASs), such as
drones, to enable them to fly farther athigher altitudes with greater frequency
and for a wider range of purposes. NICT has
been researching and developing wirelesscommunications systems that can be used
to satisfy these demands and to allow communications between UASs. We hope thatthe practical value of these NICT R&D products leads them to become de facto standards.

■ Current radio systems used bydrones and other aircraftIn recent years, drones have become widely available and are as popular a purchase as
TVs and refrigerators at electronics retailers.
Drones today are relatively easy to operate
and are capable of carrying out a variety oftasks, such as aerial videography. However,drones have caused some problems: they arereported to have nearly come into contact
with small helicopters (e.g., medivac helicopters) that take off and land in areas otherthan airports and the number of drone crashes

is increasing. Safer drone operation will require the development of new technologies
and improvement of the drone operating environment.
In general, UASs are remotely controlled
by their operators (or pilots) by means of
two-way wireless communications. UASs
are able to transmit telemetry (measurements
taken at remote locations) and image data,etc., to their operators, who send them commands. Although most UASs are operated
manually, some recent UASs are capable ofautomatic (or autonomous) flight when an
appropriate flight mode is selected.
While hobby drones normally operate
within a visual range of several hundred
meters, drones for commercial/industrial
use are expected to fly from several to tensof kilometers over mountains and buildings
beyond visual line of sight (BVLOS). The
safe operation of commercial/industrial aerial drones will require ensuring that they do
not collide with any ground-based structures(e.g., trees, power lines and buildings) or
flying objects (e.g., birds and manned helicopters). Thus, new technologies are beingsought that would enable operators to identify the flight positions and status of their

Toshinori KAGAWA
Researcher
Wireless Systems Laboratory
Wireless Networks Research CenterHe joined NICT in 2013. He is engaged in
the research on indoor location systemusing IR-UWB, and wireless system for
Unmanned Aircraft System (UAS). He is
the member of the Institute of Electronics, Information and Communication Engineers (IEICE). Ph.D. (Engineering).

Figure 1 Multi-hop transmission field test by NICT and AIST8

NICT NEWS 2019 No.5

drones at any moment and to comprehend
environmental conditions during takeoff andlanding, whether the drone is autonomous or
manually operated.
NICT has researched and developed technologies that enable operators to maneuver
their drones BVLOS, technologies that allow
drones flying in the same airspace to recognize each other's positions and technologies
capable of estimating the operable coverageand the risk of co-channel interference in thevicinity of a flying drone.

The command hopper system may also
allow commands to be relayed to drones andother target devices via radio repeaters installed in other remotely controllable drones
or ground-based unmanned robots. This application of the command hopper system may
enable the development of autonomous command transmission systems.

■ Technologies enabling BVLOS
drone operation

NICT has also been researching "Drone
mapper®" radio communications systems
that enable different operators' drones operating in the same airspace to recognize eachother's positions and avoid collision. Thissystem is expected to assist drone pilots in
identifying the locations of their drones
relative to other drones even BVLOS environment and in maintaining a safe distance
between drones. The current Drone mapper® uses specific, energy-efficient radio
frequencies within the 920 MHz band, does
not require a radio operator's license and is
inexpensive and easy to use. Positional information communication systems have been

As the operating ranges of drones and other UASs expand, the chance that they will fly
BVLOS of their operators or ground control
stations increases. NICT has therefore been
researching and developing technologies
that enable direct communications between
ground control stations and UASs and a relay transmission system (or multi-hop transmission system) called a "command hopper"that enables commands to be transmitted via
radio repeaters. We carried out several field
experiments and found that a single transmission hop (between two radio devices) can
communicate commands at distances up to
about 4 km (Figure 1). The use of multiple
radio repeaters will therefore allow UAS operating ranges to expand in a variety of ways.

■ Technologies enabling drones inthe same airspace to recognize
each otherFigure 2 Drone mapper® field test (sharing of positional information
between small manned helicopters and drones)

Figure 3 Autonomous flight control
field test using two drones

Figure 4 Technology capable of estimating the operable coverage in the vicinity of a flying drone

available for manned helicopters and aircraft, but most are relatively expensive. No
radio devices had been available that could
be installed on small UASs, such as drones,
enabling them to directly communicate witheach other. We have confirmed that the developed Drone mapper® units installed on
both small manned helicopters and drones
enabled them to locate each other's positions
within a range of about 9 km (Figure 2). In
addition, we are building on the drone mapper's abilities by researching and developing
an autonomous flight control system allowing
two-way communication between drones. In
field experiments, we succeeded for the firsttime in the world in causing two drones torecognize each other's positions and autonomously maintain a safe distance between
themselves (Figure 3).

■ Technologies estimating theoperable coverage and the risk ofco-channel interference
Expanding the areas in which drones are
permitted to operate will bring more drones
into densely populated urban areas where
ground-based radio devices are already inwidespread use. Many current drones use
ISM bands, such as the 2.4 GHz and 5 GHz
bands. Some ground-based radio devices use
similar wave frequencies and may disrupt
communications between drones and groundcontrol stations, including the transmissionof positional information and safety confirmation image data from a drone to a station.
NICT has been researching technologies
capable of estimating the operable coveragein the vicinity of a flying drone using datacollected by a measurement instrument installed on the drone (Figure 4). These technologies are intended to increase drone flightsafety by predicting and informing drone operators of radio wave interference risks.

■ Future prospects
Studies have been conducted on drone useof radio devices that have previously only
been used on the ground. The objective of
these studies is to increase the safety of thesimultaneous operation of many drones in thesame airspace. We expect that ground-based
radio devices will increasingly be integrated
into UAS technology. NICT will continue its
R&D efforts to achieve smart, aerial use ofradio waves.
NICT NEWS 2019 No.5

9

Challenges to Use RF Signals in Underwater
to Open a New Field

cean research and the exploitation

O of ocean resources have been pro-Takashi MATSUDA
Senior Researcher
Wireless Systems Laboratory
Wireless Networks Research Center
After completing graduate school,joined NICT in 2010. He engaged in R&D
in sheet medium communication andpower supply, and underwater wirelesscommunication using radio wave. Ph. D.
(Engineering).

gressing much more slowly than those ofon land despite the fact that oceans cover
approximately 70% of the Earth’s surface.
While this delay is undoubtedly due in largepart to very limited human activity in themarine environment, the lack of underwater communications and sensor technology
is also a probable cause. The developmentof new technologies enabling underwaterradio wave utilization may facilitate advances in various marine technology fields,such as submarine resource explorationand excavation, marine ecological and geological surveys and the application of IoTtechnologies in fisheries.

■ Extreme oceanic environments
significantly attenuate radio waves
Acoustic waves have been the primarymeans of underwater communications anddetection. They also have disadvantages:
because they are low frequency waves, they
are unsuitable for use in higher-speed communications and cause significant propagation delay. For these reasons, other meansof communication, including radio waves,
have been studied. However, certain properties of seawater make underwater radio wave（A）use. Seawater has electrical properties very
different from air. Its relative permittivityof approximately 81 (compared to approx.
1 for air) and electrical conductivity of approximately 4 S/m* (compared to approx.
0 S/m for air) greatly attenuate radio waves.
Lower frequency radio waves travel throughseawater more easily. Some scientists havealso been researching visible light communications underwater because certain wavelengths of blue light (which gives the ocean
its blue appearance) is known to be moreresistant to attenuation. Although the use ofvisible light enables high-speed communications, it is strongly directional and therefore
requires careful emitter-receiver alignment.
In addition, visible light may scatter in turbid
water, preventing it from reaching a receiver.
Radio wave-based underwater wireless technologies may therefore complement acoustic
wave and visible light communications whenconditions render them ineffective.

■ Prototype underwater antenna
Ground-based antennas are inadequate
for underwater use without modification. As
I explained above, the electrical propertiesof seawater are very different from those of
air and greatly shorten radio wavelengths.
To address this issue, I created a prototype（B）

Figure 1 Prototype underwater antennas enclosed in a buffer layer of purified water. (A) Magnetic loop antenna (diameter: 310 mm,
height: 200 mm, weight: approx. 50 kg). (B) Microdipole antenna (diameter: 100 mm, length: 800 mm, weight: approx. 20 kg).

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NICT NEWS 2019 No.5

antenna with its elements enclosed by a buffer layer of purified water with an electricalconductivity of 0 S/m (Figure 1A). The addition of this buffer layer isolates the antenna
more securely from the changeable ambientenvironment. Although other mediums, suchas air, could be used as a buffer layer, I chose
purified water because it allows the externalpressure applied to the antenna container tobe equally distributed, increasing its overall
structural strength when subjected to waterpressure. The prototype underwater antennais equipped with a magnetic loop. One of myobjectives at the beginning of this research
project was to accurately measure radio wave
propagation characteristics. To achieve this,I set the center frequency of the antenna to
10 MHz to ensure adequate measurement ofattenuation between antennas placed within
the same measurement system.
I also created a prototype underwater microdipole antenna that will be evaluated todetermine its properties in relation to different radio wave frequencies (Figure 1B). Thisantenna was designed to be lightweight andeasy to construct since multiple antennas
need to be produced and evaluated. Although
the radiation efficiency of microdipole antennas is lower than that of magnetic loop antennas, they have a broader effective band,making impedance matching between matching circuits easier.

■ Development of underwater radio
wave measurement systems

various experiments. The UCS is shown in
Figure 2. You can see a transmitting antenna
mounted on the far side of the UCS and threereceiving antennas attached to the near side.
The transmitting antenna was mounted on a
movable stage and is able to move 900 mm
in either direction from the central position inparallel with the array of receiving antennas.
The receiving antenna array is also mounted
on a movable table and can be moved within
the frame, enabling the distance between it
and the transmitting antenna to be adjusted.
The control unit, mounted on the lower left
corner of the UCS, controls antenna switching, communications with the network analyzer, various sensors, and other functions.
A fiber optic cable connects this control unit
with the terminal controller on the ship, enabling the ship to transmit control commands
to and receive data from the UCS. The control unit, the network analyzer, and the battery are mounted in a row. These components
are enclosed in pressure-resistant containers
capable of withstanding water pressure up
to about 100 m in depth. Using this measurement system, we were able to evaluate
the propagation properties of 10 MHz radio
waves while varying the inter-antennal distance from 60 cm to 140 cm.
I am also developing an underwater wireless measurement system with subseafloor
sensing capabilities (Figure 3). This technology uses radio waves to detect buried objects
invisible to acoustic waves and other sensory
technology. The system is designed to detectobjects buried under the seafloor by measuring radio wave propagation properties (amplitudes and phases) between antenna arrays
directed at the seafloor. I have been using thesystem to measure various types of buried
objects, such as metals, dielectrics and theircomposites (Figure 4). I am also examining

In another research project, I developed aportable vector network analyzer capable ofmeasuring electrical properties in the range
between 10 kHz and 10 MHz and an electromagnetic response measurement systemthat can be connected to an underwater cable for use in shallow seas.
The system is equipped withinterfaces to which a variety of sensors (e.g., cameras, CTD meters, tilt meters,
and underwater altimeters)
can be connected to record
environmental conditions. I
also constructed a frame (anunderwater channel sounder (UCS)) onto which thesemeasurement devices andFigure 2 Underwater channel sounder capable of shifting thesensors can be mounted that
position of the transmitting antenna attached to it while operating
can be suspended in water forunderwater

methods of estimating the sizes and shapes ofburied objects using the collected data.

■ Future prospects
The oceans are full of potential technological applications. However, the currently
available technologies are still inadequate toachieve specific objectives. If an underwater wireless technology that employs radio
waves is developed, it may enable wirelesscommunications with unmanned underwater
robots, subseafloor sensing and other new
technologies, which could be used to enhance
Japan’s marine-related industries and natural
resource development capabilities, further
strengthening its prosperity as a major maritime nation. (Part of this research project was
supported by the National Security Technology Research Promotion Fund provided by
the Acquisition, Technology and Logistics
Agency.)＊ S/m (siemens per meter): a unit of electrical conductivity
equal to the reciprocal of the corresponding electrical resistivity expressed in ohm meters (Ωm)

Figure 3 Sensing and measurement frame equippedwith one transmitting antenna and four receiving
antenna arrays

Figure 4 Sensing and measurement being
conducted on the seafloor in Mitohama, Numazu City,
Shizuoka Prefecture at a depth of 30 m

NICT NEWS 2019 No.5

11

Creating a Wireless Network to Facilitate
the Widespread Use of Robots● Biography
1985 Born in Ishikawa Prefecture,Japan
2008 Graduated from Chubu University with a B.S. in Computer
Science2013 Graduated from the University
of Electro-Communications
with a Ph.D. and then joined
NICT. Appointed to current
position.

Toshinori
KAGAWA● Awards, etc.
Won first prize in the 13th Electronics
Contest sponsored by the University
of Electro-Communications
Won first prize in the 2011 HumanMedia Lab Contest sponsored by
the University of Electro-Communications

Researcher
Wireless Systems Laboratory
Wireless Networks Research Center
Ph.D. (Engineering).

obots are expected to take on agreater role in supporting our everyday activities in the near future. They
are capable of carrying out tasks in nearly
inaccessible areas (e.g., areas affected by disasters, extreme ocean depths and remotemountainous areas). However, a new wireless system needs to be developed to enable communications with robots deployedin these areas, because currently available
wireless systems are inadequate. The LTE
network requires that a communications
infrastructure be constructed in these areasand current Wi-Fi only allows devices to access the internet.
Our team has been researching wirelesssystems that can be used to communicate with robots and drones carrying out
tasks in disaster-affected areas and remotemountainous areas. When communicatingwith robots, communications disruptions
and transmission delays (the time it takes
for a robot to receive a command after itis transmitted by the operator) should be
minimized. We have developed a communications system to achieve these goals

R

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NICT NEWS 2019 No.5

Q&As

Tool rack Kagawa installedon the wall of his house

Q How do you normally spend your holidays?
A I often go to home improvement retailers and 100-yen shops, buy

some materials, and engage in DIY activities. I sometimes makeracks for my tools and other items, but my wife complains about
my creations; she says they look awkward and unfashionable.

Q What advice would you like to pass on to people aspiring to beresearchers?

A I believe that creative thinkers have the potential to become
researchers. I recommend that they develop the habit of keenly
observing everything around them and thinking about its
underlying causes and mechanisms.

Q What are you currently interested in outside of your research?
A I am currently hooked on Japanese-style luxury bathhouses.

I alternate between a sauna and cold water to stimulate thesympathetic nervous system. This routine helps me to clear mymind and greatly increases my creativity and efficiency when
performing intellectual tasks. Many sauna lovers are familiar withthis acquired state of mind—mindfulness, so to speak.

using time-division multiplexing and a
combination of the 169 MHz band and the920 MHz band. The system is also compatible with communications relays (multi-hop
communications). Moreover, this systemallows an operator to choose whether toprioritize transmission delay or communication speed and customize the balance
between them depending on the nature of
the mission a robot is tasked with.
Wireless technologies are already soubiquitous that many people may taketheir existence and mechanisms for grant-

ed. Our mission is to leverage these well-established technologies efficiently and optimally to achieve specific goals.
Baien Miura, an Edo era Japanese philosopher, said, "The blooming of a living tree iseven more amazing than the blooming ofa dead one." In other words, ordinary technologies may enable more truly amazing
innovations than revolutionary technologies do. I hope that we are able to create
something amazing using these ubiquitous
wireless technologies.

Prototype multi-hop communications system to control drones

The MEXT Minister Prizes are bestowed to scientists who have made significant achievements
in science and technology R&D which have advanced understanding in their fields.
*The titles and organizations that the winners belong to are those at the time they won their awards.

FY2019 The Commendation for Science and Technology
by the Minister of Education, Culture, Sports, Science and Technology

Prizes for Science and Technology
Masugi INOUE

Director of the International Research
Advancement Office, Global Alliance Department,
Open Innovation Promotion Headquarters

Yasunori OWADA

Senior Researcher, ICT Testbed Coordination
and Planning Office, ICT Testbed Research andDevelopment Promotion Center, Social Innovation
Unit, Open Innovation Promotion Headquarters

next-generation access network concept, morecommonly known today as local IoT architecture. We then engaged in R&D focused onstrengthening the network’s natural disaster
resilience and put NerveNet into practical use.
NerveNet has been operating continuously inKiyoshi HAMAGUCHI

disaster-stricken Onagawa in Miyagi Prefecture
and in municipalities preparing for an anticipated Nankai Trough earthquake, such as Shirahama in Wakayama Prefecture. In addition, thetechnology has been transferred to the private
sector. We are very honored that our R&D efforts have been recognized for their practicaland innovative value and for their significant
contributions to the development of Japan.

Director General, Wireless Networks ResearchCenterOverview ●Description: Development of resilient distributed autonomous cooperative communication system●Date: April 17, 2019
Comments from the Recipients:
More than 10 years ago, we came up with aKiyonori OHTAKE

Executive Researcher, Data-driven Intelligent
System Research Center, Universal Communication
Research InstituteJunta MIZUNO

Senior Researcher, Data-driven Intelligent System
Research Center, Universal Communication
Research InstituteKentaro TORISAWA

Director General, Data-driven Intelligent System
Research Center, Universal Communication
Research Institute

Overview ●Description: Research on Disaster
Damage Analysis Technologies based on Deep
Semantic Analysis of SNS Texts●Date: April 17, 2019
Comments from the Recipients:
In response to the severe damage caused by theGreat East Japan Earthquake, we developed
DISAANA (a system capable of analyzing di-

Chihiro TAO

Researcher (Tenure-Track), Space Environment
Laboratory, Applied Electromagnetic ResearchInstitute

Overview ●Description: Research on Generation, Emission, and Variation Processes of Aurora on Outer Planets●Date: April 17, 2019
Comments from the Recipient:
Diverse planetary environments can be ideal research subjects for the purposes of testing the

From left to right: Kiyoshi HAMAGUCHI, Yasunori OWADA
and Masugi INOUE

saster-related SNS information) and D-SUMM(a system capable of summarizing disaster-related information). We appreciate the recognition our R&D efforts have received. We wereable to put our R&D results into practical use at
the local community level thanks to the advice
and support of many collaborators, including
governmental agencies—especially the Ministry of Internal Affairs and Communications—municipalities and private companies. These
supporters have our deepest thanks.

NerveNet overview

From left to right: Kentaro TORISAWA, Kiyonori OHTAKE
and Junta MIZUNODISAANA/D-SUMM overview

universality of knowledge developed throughEarth-related research and expanding thisknowledge. In addition, this type of research
may advance our understanding of the impact
of extreme space weather phenomena—such as
massive solar storms—on Earth. I am delighted
by the fact that a series of research projects I
conducted related to auroras occurring on outerplanets have been so well evaluated. I sincerely
appreciate my coauthors and collaborators fortheir support.
NICT NEWS 2019 No.5

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NICT NEWS 2019 No.5 Vol.477

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Issue date: July 2019 (bimonthly)

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