No.
12021
5

FEATUREInterview

Special Issue for Space ICT
Innovative Space
Communications Technology
Seamlessly Connecting Land,
Sea, Air, and Space
What is this movement towards a new era of space-based ICT?

Greetings for 2021
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Happy New Year!

Greetings for 2021
President of the National Institute of Information and Communications Technology

TOKUDA Hideyuki, Ph.D.
FEATURE

President of the National Institute ofInformation and Communications Technology

TOKUDA Hideyuki, Ph.D.

We pray for those who passed due to COVID-19, and we deeply respect the medical personnel working to treat the infected and seriously ill. We offer our condolences to those who passed in disasters such as the torrential rains in Japan in July
2020, we give our deepest sympathies to those affected by disasters, and we pray
for a quick recovery of the affected areas.

Special Issue for Space ICT
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4

Last year, COVID-19 spread globally and caused an un-forms, cyber security, and frontier research. We created ex-

precedented crisis. In Japan, a state of emergency was issued

cellent, world-leading technologies in space-time standards

Innovative Space Communications
Technology Seamlessly Connecting Land,
Sea, Air, and Spacein April last year and non-essential outgoing was refrained.

technologies, high-capacity transmission using new types

Even though ICT became indispensable for remote working,of multicore optical fibers, Beyond 5G / 6G, brain-inspired

online learning, and telemedicine, many issues became ap-

information processing and communications, quantum ICT,

parent, such as delays in society's digitalization. To respondand bio-ICT, etc. We accelerated the development of secu-

What is this movement towards a new era of space-based ICT?
KADOWAKI Naoto

to this “new normal,” people seek social and economic ac-rity personnel through practical cyber exercises such as CY-

tivities that avoid the “Three Cs,” and we must promote

DER, Cybercolosseo, and SecHack365.We also started NQC

society’s digital transformation by developing advanced(NICT Quantum Camp) to develop "quantum native" human

ICT infrastructure ensuring cyber security and providing

resources and IDI (Innovation Design Initiative) to support

non-contact, remote, and highly realistic experiences.

the president's thinktank functions and open innovations.

Research Activities of Space Communications Laboratory
in the 4th Medium- to Long-Term PlanTOYOSHIMA Morio

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Integration of Satellite Communications into 5G / Beyond 5G
MIURA Amane

8
Cover photoPortable optical ground station completed in February 2020
The station has a 35 cm telescope installed, which is used for the optical antenna module. Satellite-terrestrial opticalcommunications are sensitive to atmospheric conditions, so this station wasdeveloped for the purpose of realizing
optical communications by selecting alocation with favorable conditions.
This research and development was
carried out for the “Research and Development of Quantum Cryptography
Technologies in Satellite Communication(JPJ007462)” which is part of the Ministryof Internal Affairs and Communications'“Research and Development Project ofPriority ICT Technology (JPMI00316).”
Upper left figure
By using the world’s first optical communication device (SOTA) mounted on a 50
kg class microsatellite, the experimentdirected a laser beam to the NICT opticalground station in Koganei, Tokyo and succeeded in transmitting, via optical communication, images taken by the satellite’scamera.

Optimization of Global Communication Networks toConnect High-throughput and Numerous Satellites
Towards demonstration of Engineering Test Satellite-9 andnetwork control technology
ABE Yuma10

Ultra-fast Laser Communications Will Open a New Worldof Possibilities for CubeSats
Alberto Carrasco-Casado

TOPICS

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13

Experimental Success in Bidirectional OpticalCommunication Between the International Space Station
and an NICT Optical Ground Station Receives the GoodMUNEMASA Yasushi
Design Award 2020

NICT is the sole national research institute in Japan that

The Ministry of Internal Affairs and Communications

specializes in ICT. Our mission is to address social issues

also announced the “Global Communication Plan 2025,” andand create new values through the advancement of ICT. To

R&D of simultaneous interpretation AI has begun, aiming

achieve our mission, we are doing research and development

for the Expo 2025 Osaka. Furthermore, both in Japan andon the world's most advanced technologies and are promot-

overseas, we are promoting joint research and demonstration

ing technology transfer and social implementation of our

projects with research institutions, corporations, universities,

R&D outcomes through collaboration and open innovationand local governments. We also promote activities for com-projects with organizations in Japan and overseas. Looking

panies to test and verify the various advanced technologies

to a post-COVID-19 society, an open symposium was heldwith NICT testbed facilities and international standardiza-

onlline last June to discuss the "What is your new normaltion activities at the ITU, IEEE, IETF, etc.

and the Shape of Society in the Post-COVID-19 Era." To

NICT has three management motto "COC": Collabora-

realize such society, we also discussed and demonstrated ourtion, Open and innovative mind, and Challenging spirit. We

next generation ICT such as high-strength deep ultraviolet

promote non-linear R&D that can accelerate open innova-

devices, AI chatbots/multimodal voice dialogue systems,

tion with various stakeholders in contrast to traditional liner

simultaneous interpretation systems, Beyond 5G / 6G and

R&D model.

cybersecurity.

We will start a new medium- to long-term plan from April

Under NICT’s fourth medium- to long-term plan, there

this year and will continue to fulfill our social responsibili-

was steady progress in five focusing R&D area: sensing fun-ties. We appreciate your continued support and cooperation.

damentals, integrated ICT, data utilization and analytics plat-

Lastly, I wish all of you a wonderful year in 2021.

NICT’s Challengers File 14

OKURA Takuya
Low-Profile Active Electronically Steered Array Antenna Enabling
Internet Services in Small Aircraft
NICT NEWS 2021 No.1

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Special Issue for Space ICT

Innovative Space
Communications Technology
Seamlessly Connecting Land,
Sea, Air, and Space
What is this movement towards a new era of space-based ICT?
Space development is shifting from a national enterprise to the private
sector, and this trend has been accelerating in the last decade or so. In the
United States, SpaceX has sent astronauts to the ISS with the Falcon 9 rocket and Crew Dragon capsule, and it also has a plan to launch tens of thousands of small satellites and build satellite internet. In this turbulent era ofspace development, Japan is also beginning to move towards the commercial use of space. The Space ICT Promotion Initiative Forum (SPIF) wasestablished by NICT together with universities and companies to support
this trend from the technical side and further accelerate it. We spoke with
KADOWAKI Naoto, Vice President of NICT and SPIF, who has been involved inresearch since the pioneering early days of space communication technology.

Q: Commercial use of space is becoming
more active, so what is the status of private
space development in Japan?
KADOWAKI The Space Activities Act wasenacted in Japan to promote space development at the private level. It has been enforcedsince November 2018, and it can be said thatthe act has raised interest in the commercial
use of space. A variety of activities are expected in space, and satellite communications technologies are one of the most important technologies to realize them. NICT
has been researching satellite communications technologies for many years and has avast amount of accumulated technologies and

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NICT NEWS 2021 No.1

knowledge. I think that we can contribute toJapan’s space development by making use of
these research results and development capabilities.
However, in order to do so, national research institutes alone are not enough, andoutstanding private sector technologies andhuman resources are also required. Therefore, we established SPIF with the intentionof creating a place for free and open discussion of how to proceed with future researchand development, based on the field of spacecommunications.
Q: It can be properly said that this is a newera of space, but what kind of technologies

KADOWAKI Naoto
Vice President, NICTEntered CRL (currently NICT) in 1986. He has engaged
in satellite communication. After that he became visiting researcher at AUSSAT in Australia, Chief Researcher
at Adaptive Communication Laboratory, ATR, Director
General of Wireless Communication Institute, NICT.
Current position from 2017. Ph.D. (Information Science).

do we need to achieve our goals?

■Technologies supporting a new eraof space
KADOWAKI Terrestrial wireless networks
have entered the 5G era, but, at the moment,
5G is only terrestrial. I would like to use
satellite communications and develop 5G inthree dimensions.
Construction of a three-dimensional 5G
network will expand upward to the sky withdrones, airplanes, stratospheric platforms,
low earth orbit satellites, and geostationary
satellites. In the future, I would also like toconsider communications with the Moon andwith Mars.

One other thing is IoT*1, where communication shifts from places with people todata sensing in places without people, forexample, on the ocean. Ocean surface temperature, wind direction / velocity, and atmospheric pressure, etc., have a great influenceon the weather, and as such are importantdata, but there is no easy-to-use network on
the ocean right now. However, if the ocean is
networked by developing more flexible satellite communications technology, then it will
be possible to collect data in real time. You
can say that it is something like Beyond 5G,
which comes after 5G.

optical communications device for satellites, and mounting it onto a 50 kg class
SOCRATES*3 (developed by Advanced Engineering Services Co., Ltd. and launched by
JAXA in 2014) microsatellite.
Additionally, if the satellites are connected to the Internet, then they may be hacked
like on terrestrial networks. NICT also has adepartment that studies quantum cryptography and cybersecurity, so I expect that they
will collaborate as a team and promote measures against hacking.

Q: Large-capacity optical communication
technologies are becoming important, aren’t they?

Next, full-scale experiments with ETS-9*4
are getting closer and closer, aren’t they?

KADOWAKI Optical link can provide alarger communications capacity than radio
waves. Additionally, onboard satellite components for optical communications can bemade smaller than the ones required for radio
communication, so it will be easy to mountthem on the increasing numbers of small satellites and microsatellites in the future.
Another major feature of optical communication is its capability to realize quantum
cryptographic communications. In quantum
cryptographic communications using opticalwave, quantum keys must be distributed overan optical network, and at present, terrestrial
optical fiber transmission cannot reach very
far. However, if satellites and the ground areconnected via optical communication, thenquantum keys can be delivered across continents. There are already countries overseasthat have succeeded in sending quantum keys
via satellite by using relatively large satellites, but we are conducting research on sending quantum keys via small satellites.
As for quantum cryptography, NICT has
already conducted basic experiments on thefeasibility of quantum cryptographic communications by developing SOTA*2, a small■Implementing a next-generationengineering test satellite

KADOWAKI We have started the “ETS-9
Satellite Communications Project” demonstration project to respond to new communications demands in recent years. This is anattempt to demonstrate 10 Gbps class opticalsatellite communications between a geostationary satellite and the ground, and to develop and demonstrate satellite communication
technologies in the so-called Ka-band (20 /30 GHz) that are more flexible than those using radio waves. It will be the first time in theworld to demonstrate 10 Gbps optical communication between a geostationary satellite
and the ground.
The radio wave transmission antenna is
adopting active phased array antenna technology. With this, we can electronically scanbeams via a digitized beam former, and it is
an important fundamental technology for realizing large-capacity communication with
100-beam class multi-beams in the future.
Additionally, the bandwidth allocated to eachbeam can be flexibly changed by using digital channelizer technology. These technologies also enable us to dynamically control thebeam’s direction and bandwidth, increasing
radio wave utilization efficiency.
NICT is currently developing an onboard

wireless communication device in collaboration with universities and manufacturers,
and, if all goes well, ETS-9 will be launchedin 2022.

■Wanting participation of youth whowill lead the next generation
Q: What is the future outlook for SPIF’s
activities?
KADOWAKI Technological progress in thisfield is extremely fast. If something like alarge satellite takes five or six years to develop, then it may be equipped with oldtechnology by the time it is launched, andthe longer the development time, the higher the cost. Therefore, we have to consider
shortening satellite development cycles andreducing costs by using small satellites forin-orbit demonstrations. Furthermore, we arealso considering using commercial-off-theshelf (COTS) components to reduce costs.
We consider presenting a new concept of thespace development process like this to be oneof SPIF’s goals.
To that end, we would like to receive avariety of ideas and opinions, including fromuniversities and private companies, and lay
out the direction of research and development for Japanese space communication
technologies while discussing with them.
We would also like to invite students toparticipate in SPIF and to make it into a place
to talk about space together. I hope that the
number of young researchers interested insatellite communications will increase.

＊1 IoT: Internet of Things＊2 SOTA: Small Optical TrAnsponder＊3 SOCRATES: Space Optical Communications Research Advanced Technology Satellite＊4 ETS-9: Engineering Test Satellite-9

NICT NEWS 2021 No.1

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Special Issue for Space ICT

Research Activities of Space Communications Laboratory
in the 4th Medium- to Long-Term Plan
Figure 2

requently launched micro-satellites will change the world of spacedevelopment. Space development is becoming more familiar to our lives, such as
through sophisticated earth observation
satellites, satellite communication services
by constellation satellites, and a variety of
microsatellites. In our laboratory, we havean integrated total view from the Earth’s
surface to space, and we are advancing research and development of satellite communications technology using light andradio waves to enable communication withanyone, anytime, anywhere, and to realize
high-speed, large-capacity, and wide-areausage.

F

TOYOSHIMA Morio
Director of Space Communications
Laboratory, Wireless Networks
Research Center
Joined the Communications ResearchLaboratory, Ministry of Posts and Telecommunications (currently NICT), in
1994. After engaging in ETS-VI laser
communication experiments, he wastransferred to NASDA (currently JAXA),
and after doing research at Vienna University of Technology, he worked on the
research and development of onboard
satellite communication systems for
OICETS, SOTA, and ETS-9. Ph.D. (Engineering).

Figure 1 HIgh speed Communication with
Advanced Laser Instrument (HICALI),
the world’s fastest 10 Gbps classtransmission equipment onboard
the satellite

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NICT NEWS 2021 No.1

■Technology for global opticalsatellite communication network
infrastructure
In response to rising expectations for increased satellite communications capacity
and to alleviate pressure on frequency resources, we promoted the development of theHIgh speed Communication with Advanced
Laser Instrument (HICALI) onboard a satellite in order to achieve the fastest 10 Gbps
class satellite-terrestrial (Figure 1). We arealso developing and maintaining an adaptive
optics system for the NICT optical groundstation for precise tracking and reducing atmospheric fluctuation effects, and will establish basic technology for optical feeder links.
To improve optical satellite communication quality, we successfully conducted satellite-terrestrial optical communication experiments using a Small Optical TrAnsponder(SOTA) onboard a 50 kg class micro-satellite. Furthermore, we were the first to succeed with a basic quantum communication
experiment of transmitting and receiving at
the photon-level between the SOTA and an
optical ground station, and in July 2017, wepublished a paper in Nature Photonics (Fig-ure 2). Additionally, we have been collaborating globally with both domestic and overseas companies and research institutions, andpromoting satellite-terrestrial optical communication experiments. In April 2020, we
succeeded in a bi-directional optical communication experiment between the NICT optical ground station and the optical communication terminal called Small Optical Link
for International Space Station (SOLISS)
developed by SONY CSL on the International Space Station (ISS) (see p.13 of thisissue). In the future, this technology can beused for data transmission from small earth
observation satellites and for communication
to and within satellite constellations. Furthermore, we have begun research and development of miniaturized optical communicationequipment for CubeSat and unmanned aerial
vehicles, and we are aiming for 10 Gbps classdata transmissions with CubeSats (see pp.1011 of this issue).
Ensuring global information security is an
important social issue, and we are researching and developing satellite quantum cryptography technologies to solve it. In researchcommissioned by the Ministry of Internal
Affairs and Communications, we developed
a portable optical ground station vehicle using an 8-ton truck, and conducted evaluationof tracking accuracy, etc. In joint researchcollaboration, we are developing an opticalcommunication terminal for quantum cryptography (collaboration with the Advanced
ICT Research Institute and the Quantum ICT
Advanced Development Center). Additionally, a micro-satellite called RISESAT developed by Tohoku University was launched in
January 2019. The satellite embarked witha 700-g Very Small Optical TrAnsmitter(VSOTA) developed by NICT and various
experiments were conducted. The laser ranging experiments targeting satellites for which
accurate orbit and attitude information havenot been obtained were successfully con-S uccessful world-first basic experiments
in optical communication and quantum
cryptography between an optical groundstation and a micro-satellite using SOTA

duced, which can contribute to Space Situational Awareness (SSA).

■Technology for maritime /space broadband satellite
communication network
infrastructure
The conceptual designs of a next-generation broadband communication satellite system were created, and contributed
to starting the Engineering Test Satellite-9(ETS-9) project, as a new broadband, flexible, and Ka-band / optical hybrid satellite
communication system with 100 Mbps peruser (Figure 3). We promoted research anddevelopment of the high-throughput satellite
communication mission as commissioned
research by the Ministry of Internal Affairs
and Communications, and conducted research and development of satellite beacon
transmission equipment called the Common
Communication System (CCS) required foruser experiments for satellite tracking. In
addition, we completed the development of
the satellite fixed multi-beam communication equipment, which is the ETS-9’s communications mission. Additionally, the preliminary designs for the satellite operation
center for the terrestrial integrated network
control and gateway Earth stations (main andsub-stations), and vehicle Earth stations werecreated. A simulator that comprehensively
simulates the frequency / area / RF-opticalfeeder link switching control functions wasdeveloped, and the basic performance evaluation of highly efficient operations control
technology was conducted (see pp.8-9 of thisissue).
As a basic technology for future flexible on-board payloads, the effectiveness ofthe system error correction for the onboard
digital beam former (DBF) feeder array wasconfirmed. Full-digital payload technologies
onboard micro-satellites are studied, and theresearch and development of phased array

Figure 3 System image of a next-generation broadband communication satellite

Figure 4  WINDS Earth station, set up
during the 2016 Kumamoto
Earthquake

technologies for satellite constellations wereconducted. Additionally, a development of
low-speed modems for IoT/sensor networks
is promoted, which is expected to be new satellite communication use cases.
To provide broadband communication
flexibility / agility in areas with congested or disrupted terrestrial communication
networks in an emergency, in response to
the Kumamoto Earthquake (April 2016) inKyusyu, in collaboration with NerveNet,
etc., the satellite communication link by the
Wideband InterNetworking engineering test
and Demonstration Satellite (WINDS) wasestablished in Takamori Town to help ensurecommunications under the event of a disaster(Figure 4, Collaboration with the Resilient
ICT Research Center). We also participatedin disaster prevention drills, exchanged opinions, and improved the system. With regards
to measuring Ka-band propagation characteristics of mobile Earth stations using the
WINDS satellite, we measured the blocking
effect of trees, etc., while moving the terrestrial on-the-move-vehicle station, and contributed to the standardization document.
To promote satellite communications, weformulated a satellite 5G trial plan with theEuropean Space Agency (ESA) to promotecollaboration on the integration of satellites

and 5G, and are promoting it as an NICT
commissioned research project. We also set
up a study group of 19 domestic organizations on the integration of satellites and 5G,
conducted studies on use cases, technical issues, etc., and released a white paper. At the“Space ICT Promotion Initiative Forum,”established on July 1st, 2020, the 5G / Beyond 5G technology subcommittee plans tocontinue the discussion on the integration ofsatellites and 5G from our past studies (seepp.6-7 of this issue).

■Future prospects
NICT will promote cutting edge researchand development that will become world
firsts, centered on space communication technology, and will contribute to standardization
activities such as ITU-R, AWG, and CCSDS,
etc. Additionally, we will support Space ICT
Promotion Initiative Forum’s activities promoting the formation of private communities
and collaboration between different industries in the private sector, including a varietyof companies who are interested in space. We
will show the direction for future researchand development of Japanese communication and broadcast satellites and demonstration plans, and contribute to strengthening
Japan’s competitiveness.
NICT NEWS 2021 No.1

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Special Issue for Space ICT

Integration of Satellite Communications into 5G / Beyond 5G

he role of satellite communications
in 5G / Beyond 5G is attracting attention. The Space Communications Laboratory conducts research and development
on integration between Non-Terrestrial
Networks (NTN), such as satellite communications, and 5G / Beyond 5G. This paper
introduces expectations for satellite 5G /Beyond 5G integration, an image of Beyond
5G-era networks, social issues expected tobe solved by satellite 5G / Beyond 5G integration, and prospects for our laboratory’s
future activities.

T

MIURA Amane
Senior Researcher, Space Communications Laboratory, Wireless Networks
Research Center
Since 1998, he has been with the NICT,
formerly Communications ResearchLaboratory, to engage in the research on
satellite communications and antennas.
After being transferred to the ATR, heis currently engaging in the research of
the communications mission of the Engineering Test Satellite 9 and Beyond-5G
space communications. Ph.D. (Information sciences).

■BackgroundTraditionally, satellite communications
have provided global services, been less susceptible to natural disasters than terrestrial
communications infrastructure, and beenused for broadcast services, communication
services, and temporary disaster communication. On the other hand, the networks havebeen constructed independently of terrestrial
communication services because large transmission distances cause transmission delays
and restricted communication speeds. However, with recent evolutions in satellite communication technology, 5G network technology, and standardization, it is expected that
unprecedented services will appear and thatconventional services will be significantly
improved from integrating NTNs, including
satellite communications, and 5G / Beyond
5G.

■Expectations for satellite 5G /Beyond 5G integration
There are three possible motivations behind expected integration of satellite communications and 5G / Beyond 5G (Figure 1).
First, satellite communication technologies
have evolved in recent years. With the adventof High Throughput Satellites (HTS) via geostationary satellites employing large numbersof multi-beams, high-speed and large-capaci-

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NICT NEWS 2021 No.1

ty can be realized at low costs, and transmission delays can be significantly reduced via
the advent of satellite mega-constellations
plans with numerous low earth orbit satellites. Terminals have become smaller, consume less power, and have come significantly closer to terrestrial systems. There havebeen recent moves towards unmanned aircraft, such as the High Altitude Platform Station (HAPS), as communication platforms,
and the use of the three-dimensional space(from sky to space) for communications isadvancing. Second, efficient 5G integration
can be realized by deploying characteristic
5G network technologies in satellite systems,
such as software-defined network (SDN) /network function virtualization (NFV), network slicing, and network orchestration, andpublic-private joint projects in Europe are
becoming more active to develop these technologies. Third, in realizing communication
services, satellite communications have traditionally been standardized independentlyof terrestrial mobile communications, but
now with 5G, the standardization of NTN, including satellites, is proceeding together withthat of terrestrial mobile communications. It
is expected that once NTN standardization
will progress, plug-and-play features, communications chips, as well as service realization legislation will be developed.

Figure 1

Expectations for satellite 5G / Beyond 5G integration

important to have integrated network control
technology connecting all elements, technology accommodating diverse communications
on geostationary / non-geostationary satellite
communications platforms, technology forconstructing networks from HAPS / unmanned aircraft, and terminal technology forconnecting with all users. Research, development, and demonstrations of these technologies are required.

■Social issues expected to besolved by satellite 5G / Beyond 5G
integration
It is expected that a variety of social issues
will be solved by realizing a three-dimensional integrated network, with NTN using
satellites 5G / Beyond 5G integration as a key(Figure 3). The shortage of communicationlines in the ground, sea, air, and space, which
will be utilized more actively in the future,
will be solved by providing appropriate communications for all mobilities, such as ships,
flying cars, drones, (unmanned) aircraft, andspace planes. This will realize IoT usages

Figure 2

such as MaaS (Mobility as a Service) andseamless logistics, and will expand industrial
ICT utilization in marine and non-residential
areas. In response to Japan’s future issuesof aging and population decline, NTN withwide coverage will promote the strengthening and diversification of communications
infrastructure in depopulated areas where itis difficult to lay terrestrial communications,and will contribute to promoting smart cities and unmanned operations (autonomous /remote control). For intensifying natural disasters, which have become a serious issue
in recent years, 5G technology can realize
rapid network switching, and, more than withconventional satellite communications, itwill be possible to maintain a seamless communication environment in disaster relief
and strengthen terrestrial communication infrastructure such as mobile phone networks.
Furthermore, with the new normal from the
spread of COVID-19, NTN is expected toprovide unmanned operation by taking advantage of NTN’s wide coverage, provide
appropriate medical services via telemedi-■Beyond 5G era networks
Networks in the Beyond 5G era are premised on communication networks in whichspace and the ground are connected in three
dimensions via multiple layers (Figure 2).
By seamlessly integrating the ground, sea,sky, and space by linking terrestrial systems,
ships, drones, HAPS, and geostationary /non-geostationary satellites, we can realize
diverse communication between people andaccelerate the resolution of social issues ina constantly changing society. In realizing
three-dimensional integrated networks, it is

Figure 3

Beyond 5G era network image

cine, and local revitalization by providing
remote work environments in rural areas.

■Future prospects
The Space Communications Laboratory
held the “Study Group on the Integration ofSatellite Communications and 5G / Beyond
5G” in FY2019, and, with relevant organizations in Japan, we conducted concrete studies on integrating satellite communications
and 5G / Beyond 5G and released the report(https://www2.nict.go.jp/wireless/sat5g-scl.
html (in Japanese)). We are continuing these
activities and will support the “5G / Beyond
5G Integration Technology Subcommittee”
through “Space ICT Promotion Initiative Forum” (https://spif.nict.go.jp/ (in Japanese))
activities. With the integration of NTN and
5G / Beyond 5G, including satellite communications, as the key, we will promote activities in this field in Japan towards realizationof three-dimensional integrated networks,
solving social issues, and creating new services. Additionally, as research and development initiatives, we will promote researchand development of core technologies forrealizing three-dimensional integrated networks, such as integrated network control
technologies, and, in collaboration with Europe, Beyond 5G satellite / terrestrial integration technologies.
In our laboratory, we aim to connect the
ground, sea, sky, and space in a seamlessthree dimensional manner, thereby enabling
communications to all areas. Through this,we will continue to work to realize communications that can provide new lifestyles andwork styles to ever-changing society.

Social issues expected to be solved by satellite 5G / Beyond 5G integration

NICT NEWS 2021 No.1

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Special Issue for Space ICT

Optimization of Global Communication Networks to Connect
High-throughput and Numerous Satellites
Towards demonstration of Engineering Test Satellite-9 andnetwork control technology
atellite communication systems are
expanding in scale due to the rapid
increase in satellite numbers, and additionally, communication satellites are becoming
more sophisticated. At NICT, we are aiming
to realize satellite communication systems
that can be operated efficiently, advanceresearch on control models and optimization algorithms for resource allocation andnetwork construction, and are planning todemonstrate a portion of the technologies
by using Engineering Test Satellite-9 (ETS9), scheduled to be launched in FY2022.

S

ABE Yuma
Researcher, Space Communications
Laboratory, Wireless Networks
Research Center
After completing his master course, hejoined NICT in 2017 and completed his
doctoral course in 2020. He is currently
engaged in the Engineering Test Satellite 9 project and research on resourceand network management for largescale satellite communications systems.
Ph.D. (Engineering).

Reference[1] Amane Miura, Toshihiro Kubooka, and Eiichi Sakai, "Activity
to Establish Communications Technology on Next Generation High Throughput Satellite by the Engineering Test
Satellite 9," IEICE, vol.102, no.12, pp.1080-1084, 2019. (in Japanese)[2] Yuma Abe, Hiroyuki Tsuji, Amane Miura, and Shuichi Adachi,“Frequency Resource Management Based on Model Predictive Control for Satellite Communications System,” IEICE
Transactions on Fundamentals of Electronics, Communications and Computer Sciences, vol.E101-A, no.12, pp.24342445, 2018.
DOI: https://doi.org/10.1587/transfun.E101.A.2434[3] Y uma Abe, Masaki Ogura, Hiroyuki Tsuji, Amane
Miura, and Shuichi Adachi, “Resource and Network Management Framework for a Large-Scale Satellite Communications System,” IEICE Transactions on Fundamentals ofElectronics, Communications and Computer Sciences, vol.
E103-A, no.2, pp.492-501, 2020.
DOI: https://doi.org/10.1587/transfun.2019EAP1088

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NICT NEWS 2021 No.1

■Background of satellite
communications
Satellite communication between spacecommunication satellites and the ground ismainly used in places where it is not possible
to connect to terrestrial communication networks. A familiar example of satellite communication is in-flight internet, where aircraft
and ground stations communicate via satellites. Additionally, satellite communication
can provide communication links even whenmany terrestrial networks are unavailable,
such as after a disaster. Furthermore, the demand for the Internet of Things (IoT) communications has rapidly increased in recent years,
and there is demand for increasing the capacity of satellite communication systems.

■Overall plan for ETS-9
In order to make effective use of limited
radio resources, at NICT, we are promoting
research and development on technologies
that increase satellite communication capacityand flexibility, and we are aiming for demonstration with ETS-9, scheduled to launch in
FY2022 [1].
Figure 1 shows an overview of the ETS-9
communication missions. ETS-9 is equippedwith fixed-beam, variable-beam, and opticalfeeder link communication missions, withJapan Aerospace Exploration Agency (JAXA)
developing the satellite bus system and NICT
developing the communication missions. The
technologies to be demonstrated on ETS-9
roughly fall into two categories shown below:

Common communication
subsystemC

Figure 1

Figure 3

E TS-9 communication missions (mainsubsystems being developed by NICT)I mage of network optimizations for large-scale satellite
communication systems

Frequency / Area Flexibility Technology
With conventional communication satellites, the communication resources allocatedto each region are fixed, so if communication
demand suddenly increases at a certain time,such as during a disaster, then many users may
not be able to communicate.
Satellite communication flexibility technologies solve this problem. Frequency flexibility technologies are functions that can
flexibly change frequency bands, and area
flexibility technologies are functions that can
flexibly change available communication areas.
By using these technologies and controlling satellite communication missions in
response to user requests, it is possible to allocate the required amount of communication
resources to the required location, and ETS9 is equipped with a communication mission
to achieve this. It uses frequencies in the 20
to 30 GHz band (Ka band), and the goal is toachieve transmission speeds of 100 Mbps per
user.
Figure 2 shows simulation results using
the frequency flexibility control algorithm
proposed by NICT. This simulation assumes
satellite communication services to an aircraft, and it can be seen that communication
resource allocations change as the communication requests change over time [2]. By using
communication satellites with functionality
like this, we believe that the number of people
who can communicate will increase more thanever, even after a disaster.
Optical Feeder Link Technology
Optical communication, when comparedwith communication using radio waves, has

A: Simulation of communication satellite beam placement
Figure 2

B: Simulation results of frequency flexibility function

Simulation results using the frequency flexibility control algorithm

characteristics such as large capacity, highconfidentiality, and low power consumption.
If current radio wave communications can be
replaced by optical communications, then we
can not only realize larger capacity communication links, but we will also contribute tosolving the shortage of radio wave resources.
With ETS-9 we plan to realize a 10 Gbps
class communication link between a geostationary orbit and the ground, and we arepromoting the development of HIgh speed
Communication with Advanced Laser Instrument (HICALI) for that purpose. HICALI
has a 15 cm diameter antenna and a 1550 nm(C-band) wavelength laser, which conforms
to the international standards discussed by
the Consultative Committee for Space Data
System (CCSDS) standardization body. We
also aim to establish a screening process forspace-based usage of optical network devices
used on the ground. On the other hand, light issignificantly impacted by the atmosphere andclouds, so disturbances to or shielding of the
optical signal will lead to deteriorated communication quality even if a large-capacity communication link can be constructed. As such,
we are also conducting research on adaptive
optics technologies that reduce the effects

of atmospheric fluctuations and site diversity technologies that switch between opticalground stations situated in multiple locations.

■Research on networks connecting
very large numbers ofcommunication satellites
There have been satellite constellation systems planned in recent years that can provide
a global communication network with large
numbers of communication satellites, and it
is expected that such large-scale satellite communication systems in the future will have satellites with different orbits, frequencies, sizes,
and power, etc. Additionally, it is necessary
to optimize the network to always provide astable communication link according to temporally varying user numbers and their communication requests, the number of satellites
that can be used, and the propagation state of
their electromagnetic waves.
The author proposed and developed amodel for efficiently operating a large-scalesatellite communication system and a control
scheme for dynamically optimizing the entire
network (Figure 3). With this model, satellites
with different orbits and different frequencies
can be added to the system in the same frame-work. Furthermore, it is possible to avoid frequent changes in network structure that are aburden to satellite communication operators.
Based on this model, optimal control
schemes, and operational scenarios for largescale satellite communication systems, the effectiveness of the proposed method was confirmed via simulation, and the author believes
that performance can be further improved
even if the system expands and the number ofsatellites gradually increases [3].

■Future prospects
In addition to the technologies introduced
here, at NICT, we are also conducting research on integrating satellite communications
and 5G, and we are considering using ETS-9
as a demonstration testbed. By realizing satellite communication systems that can provide
large-capacity and flexible communication
links, we believe that user communication requests will be possible anywhere, on aircraft,ships, remote islands, deserts, mountains, andeven planets. In order to realize such a world,
NICT will continue promoting research on
new satellite communication systems and will
disseminate the results.

NICT NEWS 2021 No.1

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Special Issue for Space ICT

Ultra-fast Laser Communications Will Open a New World ofPossibilities for CubeSats

ubeSat microsatellite technology has

C made great progress in the last de-Alberto Carrasco-Casado
Researcher, Space Communications
Laboratory, Wireless Networks
Research Center
After completing his Ph.D. in electric,
electronic, and automation engineering from Carlos III University of Madridand Spanish National Research Council
in 2015, he joined the Space Communications Laboratory, at NICT. Currently
engaged in several projects related tospace optical communications, ranging
from the development of terrestrial infrastructure, aerial demonstrations using drones and HAPS, to space missions
using different kinds of platforms, fromCubeSats to large geostationary satellites.

10

NICT NEWS 2021 No.1

cade. The cost of developing small satellites
has become reasonable, which has significantly increased the number of users, andthis trend is expected to steadily continue
in the future. Going forward, CubeSats willplay an active role in a variety of scenarios,
from short-term missions for university educational purposes to mega constellations
that will support communications for millions of people, and it is expected that ultra-large capacity optical-communication
technology will open up a new world of
possibilities for CubeSats.

■CubeSat overview
CubeSats are microsatellites composedof basic units (1U) with 10 × 10 × 10 cm external dimensions. Two basic units are called
2U, three basic units are called 3U, and so on.
Approximately 80% of launched CubeSats
are between 1U and 3U in size. The modular
development of small-satellite technology has
made it easier to access space, and over thelast few years, more than 1,000 CubeSats havebeen launched, with this number increasing
every year.
CubeSats have reached a high level oftechnical maturity, and are now ready to be
used not only for educational purposes andsimple experiments, but also for full-scalemissions. However, terrestrial and satellite
communication still depends on radio frequency (RF) communication, which has data
rates in the “Kbps” class and where spectrum
is already congested, so it is difficult to meetthe increasing demand for data transmission to
the ground. Optical communication, a promising technology to solve this problem, has thepotential to improve transmission speeds byseveral orders of magnitude while keeping thesize, mass, and power of onboard optical-communication terminals low.

■Role of high-speed opticalcommunication for CubeSats
As mentioned above, the basic technology
for communication between CubeSats and theground is VHF/UHF, and typical transmission
speed is around 10 Kbit/s. With large terrestrial
antennas, the S-band can reach several Mbit/s
and the X-band can reach hundreds of Mbit/s,
but with CubeSat size, mass, and power constraints, it is difficult to dramatically improve
communication speeds via RF technologies.
Furthermore, already congested spectrum is ina difficult position to support the huge numberof satellites that will be launched in the coming years. Moreover, space optical communications have a very-high potential, not only toincrease communication speeds while reducing size, mass, and power, but also with roomfor further improvement in the future.
There is a very wide range of applications
that can benefit from the increased transmission capacities of CubeSats and small satellites, including communication networks,
space observation, Earth monitoring, disasterprevention, deep-space exploration, Internet-of-things device connectivity, basic andapplied research, education, etc. There are
already plans to use CubeSats in all of theseareas, but with the future availability of highspeed communications, it is possible to thinkof even more new applications. For example,
mega constellations can be deployed at a fraction of their current cost, enabling high-speed
communications in remote locations andsignificantly reducing latency. The numberof deep-space exploration missions, currently only accessible by space agencies, could
also grow significantly due to lower costs.
Most importantly, communication speed iscurrently the most-important bottleneck for
CubeSats, so expanding CubeSat capabilities
and providing them to the general public may
bring completely new applications that no one
could have imagined. This is the true value of

Figure 1 0-year evolution at NICT of transmission speeds and mass of onboard
2
equipment for optical communication with low-earth orbit satellites

CubeSats, and optical communications are expected to open up a whole world of new possibilities for them.

■NICT’s advantageous position
NICT has a long history of research anddevelopment in the field of optical satellite
communications. With regards to only low
earth orbit (LEO) satellites, in 2006, NICT
succeeded for the first time in the world indemonstrating optical communications between LEO and the ground at 50-Mbit/s using
the Optical Inter-orbit Communications Engineering Test Satellite (OICETS), and less than
10 years later, NICT developed the world’s
first laser-communication terminal for microsatellites called Small Optical TrAnsponder(SOTA), with 5-kg of mass. The SOCRATES
satellite, equipped with SOTA, conducteda variety of experiments since 2014, such as
10-Mbit/s optical communication with theground, and basic quantum-cryptography experiments. Currently, we are aiming to reduce
mass and increase communication speedswith a LEO optical-communication terminal
called CubeSOTA, designed for the CubeSat
platform. As shown in Figure 1, it is expectedthat communication speeds will be increasedby two to three orders of magnitude and thatmass will be reduced by more than one orderof magnitude.
CubeSats can be put into orbit by launching them on a rocket, or they can be released

Figure 2

The CubeSOTA mission’s demonstration experiment plan: irect communication with the ground (center) and CubeSat toDground communication via a data relay satellite (left and right)

into space from the International Space Station(ISS). Japan is in an advantageous position
because it has its own mechanism to release
CubeSats from the ISS’s Japanese Experiment
Module (JEM) using a robotic arm. The advantages of using the ISS are frequent launch
opportunities (approximately 6 times a year),that vibration can be reduced by a dedicatedcontainer, and that CubeSats can be checkedin advance by an astronaut before their release. The disadvantage though is that theISS’s low orbit (approximately 400 km) limits the satellites to a lifespan of approximately one year, which is sufficient for technicaldemonstrations.

■Current research and development
efforts at NICT
Based on the experience miniaturizing
SOTA, we are developing an even-more-compact communication terminal for CubeSats,
which will demonstrate, in cooperation with
the University of Tokyo, multi-gigabit communication using two CubeSOTA satellites(Figure 2). The first one will carry out directcommunication with the ground, and for thesecond one, we are considering a system thatcan perform intersatellite communication via adata relay satellite in GEO orbit.
Challenges in development include miniaturizing optical amplifiers, telescopes, precision tracking, and modems. As a first step
before launching the satellite for the purposeof demonstration and experiments, we areconsidering the use of high-altitude platformsystems (HAPS), that can fly as high as 20 km,
well above the clouds just like satellites, but
in a less-strict environment. We are also researching to develop portable ground stations
that enable experiments in various locations
at a low cost, and we are also conducting research and development on ground technologies that can be easily deployed to support
high-speed CubeSat communications at amore-affordable cost.
At NICT, we are not only demonstrating
the feasibility of high-speed communications
for CubeSats, but also aiming to popularize
it by miniaturizing optical-communicationequipment, with the goal of developing an
NICT prototype device based on a design thatallows transfer of its technology to the private sector for future commercialization. It is
hoped that enabling high-speed communications for microsatellites will promote innovative scientific research and the development ofcompletely new applications.

NICT NEWS 2021 No.1

11

File 14
Experimental Success in Bidirectional Optical Communication
Between the International Space Station and an NICT Optical
Ground Station Receives the Good Design Award 2020
Space Communications Laboratory, Wireless Networks Research CenterT

he Development of Space Optical Communication System
SOLISS (Small Optical Link for International Space Station), a
joint research initiative undertaken by NICT, has received the Good
Design Award 2020 from the Japan Institute of Design Promotion,
which was jointly awarded to JAXA, Sony CSL, Ricoh, and NICT.
For the SOLISS project, NICT, in collaboration with Sony Computer Science Laboratories, Inc. (Sony CSL), used laser light to demonstrate bidirectional optical (satellite) communications between theInternational Space Station (ISS) and an NICT optical communication ground station. The features of optical satellite communication are that it can realize much higher speeds and larger capacity
communication than satellite communications with radio waves,and NICT has been leading the research and development of optical satellite communication systems since the 1980s. In the field ofspace communications, research and development led by national-scale institutions has traditionally been the mainstream, but inrecent years, there has been active worldwide development led byprivate companies, with one example being SpaceX’s first successful manned flight under NASA’s Commercial Crew Development
program.
NICT promotes open innovation not only for research and development, but also to widely implement the results in society, and,as part of those activities, NICT and Sony CSL have been jointly conducting research since 2018 towards demonstrating bidirectional
optical communication between NICT’s optical-communication
ground station and SOLISS, which was jointly developed by SonyCSL and JAXA. As a result of providing knowledge based on thedeveloped technologies for NICT-owned satellite-mounted opticalcommunication terminals and by jointly conducting the measurements and experiments necessary for the SOLISS in-orbit demon-

MUNEMASA Yasushi

stration test, on March 11, 2020, we succeeded in establishinga 100 Mbps bidirectional optical communication link between
SOLISS and the NICT optical-communication ground station, andthen transmitted high-definition (HD) image data via Ethernet. The
picture was image data transmitted from SOLISS, mounted on the
ISS’s external Japanese Experiment Module (JEM) "Kibo" platform,
and was received by NICT’s optical-communication ground station.
This result is also the world’s first example of realizing Ethernet
communications via an optical-communication device for mounting on small satellites.
The success of this experiment is the result of NICT providing
knowledge on the development of optical satellite communication
systems and providing technical support related to the experimental operation of optical ground stations, of JAXA supporting thelaunch of SOLISS and its in-orbit operation aboard the ISS, and ofSony CSL conducting the communication test. By creating such a
flexible research and development framework, utilizing the knowledge and facilities of public research and development institutions
and combining the outstanding technology and sense of speed
from private companies, the experiment was assessed as an example demonstrating, in a short period of time, function and performance not found in conventional space development.
NICT will continue to carry out advanced optical satellite communication technology research and development, and will promote open innovation of space ICT so that it can contribute tostrengthening space communications technologies in Japan. Last
but not least, we would like to thank all related organizations fortheir cooperation in this demonstration experiment and in receiving the Good Design Award.

Photo H igh-definition (HD) image taken with a 360° field of view monitor camera mounted on SOLISS
Right side: SOLISS optical communication module; Left side: Next-generation high-definition camera (HDTV-EF2)

12

NICT NEWS 2021 No.1

Low-Profile Active Electronically Steered Array Antenna
Enabling Internet Services in Small Aircraft● Biography

OKURA Takuya
Researcher, Space Communications Laboratory, Wireless
Networks Research Center
Ph.D.(Engineering)

1990 Born in Okayama Prefecture2012 	Graduated from Yokohama
National University, Faculty ofEngineering with Electrical andComputer Engineering
2013 	Completed first two years of
doctoral program at Yokohama
National University, Graduate
School of Engineering in
Physics, Electrical and Computer
Engineering
2016 	Completed doctoral program at
Yokohama National University,
Graduate School of Engineering in
Physics, Electrical and Computer
Engineering, and joined
Microwave Factory Co., Ltd.

Q What do you like the most about being a researcher?

A Being able to experience the latest technology is the firststep in bringing an “It’d be great if we could do this...” typeidea to life. I can also go to a variety of places for academic
conferences and experiments (with local gourmet foodbeing one of the pleasures).

Q What are you currently interested in outside of yourresearch?

A Driving.

I signed up for a car sharing program after feeling that
COVID-19 made traveling by public transportation a bitscary. At first, it was simply a means of transportation, but
the driving itself gradually became fun. Someday, I want tobuy a car I love.

2017 	Joined NICT, current position

Q What advice would you like to pass on to people aspiring● Awards, etc.

to be researchers?

2020 	Recipient of the Institute ofElectronics, Information andCommunication Engineers’ 2019(82nd) Communications Society
Young Researcher’s Awardecently, the demand for Internet
access by people on board large
aircraft has been increasing alongside thedevelopment of mobile phones. Additionally, according to the future trends in commercial aircraft and the defense / spacemarket that Boeing announced in October
2020 (Boeing Market Outlook, BMO), thenumber of commercial aircraft is expected to increase from 25,900 to 48,400 overthe next 20 years. Furthermore, according
to demand forecasts by aircraft model, demand for small / medium-sized aircrafts
such as regional aircraft (90 seats or less)and narrow-body aircraft (90 seats or more)is expected to be approximately 35,000 aircraft. It is expected that demand for aircraft
satellite communications will significantly increase in order to provide broadband
services for both these aircraft as well as forlarge aircraft. Therefore, effective use of frequencies has become an essential issue toincrease the speed and capacity of satellite
communication systems, and higher performance aircraft-mounted satellite communication antennas are required.

R

Q&As

A When I was a student, I was assigned to a laboratory andfound it fascinating, thinking, “Research is quite interesting,”
so I decided to get a Ph.D. and become a researcher. If you
feel the charms and allure of research, then I hope you willcherish that feeling and become a researcher.

Generally, it is necessary to increase theantenna’s aperture to improve its performance. However, with conventional mechanically driven antennas, the antenna
becomes three-dimensionally large, whichmakes it difficult to mount on small / medium-sized aircraft. Therefore, through research and development of a low-profile
active electronically steered array antenna,
we aim to contribute to effective frequency utilization by establishing technology
to improve antenna performance withoutcompromising aircraft mountability andimproving frequency utilization efficiency
by more than 30% with multi-value modulation methods.

FigureBy the end of the current fiscal year, weplan to actually mount a sub-array antenna,
which is part of the array antenna, on an
aircraft and evaluate the antenna’s performance. If we achieve our targets without
any problems, then I believe that this will be
the first step towards significantly changing the in-flight internet environment.
(This study is conducted under the commissioned research of the “Research and development on narrowband technology using
active electronically steered array antennathat can be mounted on small aircrafts”(JPJ000254) by the Ministry of Internal Affairs and Communications, Japan.)

Merits of active electronically steered array antenna

NICT NEWS 2021 No.1

13

NICT NEWS 2021 No.1 Vol.485

Published by Public Relations Department, National Institute of Information and Communications Technology
Issue date: January 2021 (bimonthly)

4-2-1 Nukui-Kitamachi, Koganei, Tokyo
184-8795, Japan
TEL: +81-42-327-5392 FAX: +81-42-327-7587

URL: https://www.nict.go.jp/en/

ISSN 2187-4050 (Online)