1 Introduction

The development of the current Engineer-ing Test Satellite VIII (ETS-VIII) is one partof a Japanese satellite development projectdesigned to develop the fundamental technolo-gies for next-generation mobile satellite com-munications and satellite positioning systems.Specifically, the goals of this project are todevelop the following new technologies, in-orbit tests, and experiments [1]-[3].

- Bus technology for a three-ton-classlarge geostationary satellite bus

- Large-scale satellite-borne deployablereflector

- Mobile satellite communications usingsmall ground stations such as handheldterminals

- Fundamental technologies for satellitepositioning systems

Bus technology for a three-ton-class largesatellite will prove essential in any next-gener-ation communications system designed tomeet increasing demands for higher-capacitycommunication. This technology is alsoexpected to serve a range of further applica-

HAMAMOTO Naokazu et al. 3

2 Overview of the Engineering TestSatellite VIII (ETS-VIII) Project

HAMAMOTO Naokazu, YOSHIMOTO Shigetoshi, and IMAE Michito

The Engineering Test Satellite VIII (ETS-VIII) project started from a conceptual design fora mobile satellite communications and broadcasting system produced by the Ministry ofPost and Telecommunications in 1992. The aim of this project is to develop fundamentaltechnologies for mobile satellite handheld phone services and digital sound broadcastingservices using the S-band frequency. To develop the required technology in Japan, theJapan Aerospace Exploration Agency (JAXA), the Communications Research Laboratory(CRL), and other organizations have collaborated to develop a large satellite bus, large scaledeployable reflectors, a phased array antenna feed system, onboard signal switching equip-ment for voice and data communications, a high-accuracy positioning system, and so on.The development of the onboard components is almost complete and a ground test of thesatellite system is being conducted at JAXA’s Tukuba Space Center in preparation forlaunching the satellite in 2004. This report presents an overview of the history of the ETS-VIII project, the organizational structure, and the in-orbit experiments.

Keywords Engineering Test Satellite VIII, AMobile satellite communication, Mobile satellite broad-casting, Development of fundamental technology, S-band frequency

1 Formed in January, 2001, through the consolidation of the former Ministry of Posts and Telecommunications, the former Manage-ment and Coordination Agency, and the former Ministry of Home Affairs. The Ministry of Public Management, Home Affairs,Posts and Telecommunications referred to in this paper is equivalent to the former Ministry of Posts and Telecommunications.

2 Formed in January, 2001, from the former Ministry of Education, the former Science and Technology Agency, and other bodies.The Ministry of Education, Culture, Sports, Science and Technology referred to in this paper is equivalent to the former Scienceand Technology Agency.

3 Organization formed in October, 2003, from the former National Space Development Agency of Japan, the former Institute ofSpace and Astronautical Science, and the former National Aerospace Laboratory of Japan. JAXA, as referred to in this paper, isequivalent to the former National Space Development Agency of Japan.

4 R&D Corporation funded by the Japan Key Technology Center and private companies. Completed its mission in March, 2001.

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tions in the establishment of an overall spaceinfrastructure. At the same time, the large-scale onboard deployable reflector will proveessential in establishing a satellite-basedsmall-terminal mobile phone system. Thetechnology used to develop this antenna willin turn be applicable to future large orbitalstructures, such as a geostationary platform.

Currently a great deal of attention has beenfocused on new forms of next-generationmobile satellite communications. If we are torealize these new communication services, wemust first develop multi-beam onboard anten-nas and design a communications switch foronboard satellite deployment. Efforts such asthese to develop fundamental satellite posi-tioning technologies will not only enhance andsupplement existing systems but will also leadto the development of new, original systems.Fig.1 illustrates some of the services madepossible through the technological develop-ments associated with the ETS-VIII.

This satellite development initiative is ajoint project of the Communications ResearchLaboratory (CRL), the Japan AerospaceExploration Agency (JAXA)3, the AdvancedSpace Communications Research Laboratory(ASC)4, and Nippon Telegraph and TelephoneCorporation (NTT), with the central support ofthe Ministry of Public Management, HomeAffairs, Posts and Telecommunications(MPHPT)1 and the Ministry of Education,Culture, Sports, Science and Technology(MEXT)2. These groups have worked dili-gently to develop the satellite, onboard sys-tems, and required ground-station facilities,aiming to launch the ETS-VIII in 2004 (usingthe H-IIA rocket at the JAXA TanegashimaSpace Center).

After launch, project members will con-duct in-orbit tests of the satellite-borne sys-tems and basic mobile satellite communicationand positioning experiments. In addition,domestic/overseas universities, research insti-

Journal of the National Institute of Information and Communications Technology Vol.50 Nos.3/4 2003

Services imageFig.1

tutes, and enterprises plan to conduct experi-ments in a variety of satellite communicationapplications. The national institutes will thusserve as a central entity facilitating high-risktechnological development and orbital fieldtesting for a wide range of organizations.These collective efforts will, it is hoped, con-tribute to the space exploration activities oftomorrow’s more technology-oriented Japan.This report describes the background and out-lines the schedule of this new satellite project.

2 Background and organizationof satellite development

With the launch of the Engineering TestSatellite V in 1987, the MPHPT, MEXT, CRL,JAXA, NTT, and others initiated a program todevelop the fundamental technology for anintegrated mobile satellite communication sys-tem that would span maritime, aeronautical,and land mobile communications. Encour-aged by the success of this program, in 1996the NTT group launched the N-STAR, provid-ing Japan with its first domestic commercialmobile satellite communication service.Specifically, the N-STAR inaugurated 2.5-GHz / 2.6-GHz (S-band) commercial ship andautomobile satellite telephone services for theJapanese land mass and neighboring seas.

Four years earlier (in 1992), the Ministryof Posts and Telecommunications (now theMPHPT) had begun work on the conceptualdesign of an R&D satellite for next-generationmobile satellite communications/broadcastingsystems. At first, the goal was to develop anext-generation communications/broadcastingR&D satellite equipped with a large deploy-able reflector that would enable S-band fre-quency mobile satellite digital sound broad-casting. The goal was revised in 1993, how-ever, to a more ambitious conceptual design: amobile satellite communications/broadcastingsystem equipped with two large deployablereflectors allowing mobile satellite communi-cations using compact ground stations assmall as hand-held terminals. Work on thisconceptual design indicated that development

of such a system would indeed be possible,leading to the approval of the project by the1994 Space Activity Committee. Specifically,the Committee authorized the development ofmission systems through joint work betweenthe MPHPT and the CRL, while JAXA was topursue research on a next-generation field-testing system.

In March 1994, the Advanced Space Com-munications Research Laboratory (ASC), aresearch corporation funded in part by theJapan Key Technology Center and in part bythe private sector, was established to pursueresearch and development of mission systemsin collaboration with the CRL.

Later, a “Symposium on a Next-Genera-tion R&D Satellite” [renamed the “Sympo-sium on the Engineering Test Satellite VIII(ETS-VIII)”] was convened by the MPHPT,MEXT, CRL, JAXA, NTT, and the ASC. Par-ticipants in the symposium investigated issuesrelated to a number of system elements,including the large-scale geostationary satel-lite bus, the large deployable reflector, andonboard mission systems.

In FY1997, the Space Activity Committeeapproved the framework of the ETS-VIIIdevelopment program, and JAXA provided apreliminary design for the satellite. JAXA andthe CRL then proposed a high-precision timestandard and time-comparison system as ele-ments of the overall onboard system, with thenewly stated goal of establishing the funda-mental technology for future satellite position-ing in addition to the R&D for mobile satellitecommunication systems. In FY1998, theentire satellite development project was offi-cially approved and full-scale development ofthe satellite began. In April 1999, the satellitesystem was subject to a preliminary designreview (PDR), followed in November 2001 bya critical design review (CDR), after whichthe project entered the current stage of designfollowup. Fig.2 shows the developmentorganization, and Table 1 shows the develop-ment schedule.

In the initial stages of conceptual design,the ETS-VIII was to be launched in 2000 or

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2001. This was postponed to 2002 when theSpace Activity Committee approved the R&Dproject. This date has been further postponedto 2004 due to the unsuccessful launch of theCommunications and Broadcasting Engineer-ing Test Satellite (COMETS) into geostation-ary orbit in 1998 and to delays in developmentof the H-IIA rocket, delays attributable to thefailed launch of the multifunctional transportsatellite (MTSAT) in 1999.

The ETS-VIII is scheduled to be launchedby the H-IIA into geostationary orbit at 146

degrees east longitude. The original ETS-VIIIprogram included a digital sound broadcastingexperiment utilizing the through repeatermode. However, acquisition of the appropri-ate license to operate a wireless station hasproven problematic due the likely review ofthe use of the 2,535 to 2,540-MHz satellitesound broadcasting band promoted by theMPHPT. Additionally, securing of a licensehas been slowed by the incompatibilitybetween the proposed spread-spectrum tech-nology standard and the OFDM method to beemployed by the ETS-VIII (in conformitywith standards established by the EU). Toaddress these issues, separate experiments arescheduled to assess OFDM multicasting in thecommunication band.

3 Development themes andresponsibility

The success of the ETS-VIII will dependon the development of a number of importantelements: a large geostationary satellite bus, alarge deployable reflector system (including a

Journal of the National Institute of Information and Communications Technology Vol.50 Nos.3/4 2003

Schedule of ETS-VIII developmentTable 1

Organization structure for satellitedevelopment

Fig.2

feeder unit), mobile communications missionsystems, and a high-precision time standardsystem. Development of the foregoing maybe outlined as follows.(1) Large geostationary satellite bus

The technology behind the three-ton-classlarge geostationary satellite bus is an essentialelement in the infrastructure of an expandingrange of space communications/broadcastingsystems. This next-generation satellite bustechnology includes modularization of thesatellite body to facilitate satellite integration,autonomous control via onboard computer,development of a 7-kW high-power genera-tion and 100-V bus power supply, and installa-tion of an ion engine that will provide north-south orbital control throughout its long serv-ice life.(2) Large deployable reflector system

The large deployable reflector system con-sists of an onboard high-gain antenna that willbe essential to any mobile satellite communi-cations/broadcasting system using compactground stations such as mobile terminals.Development in this area is primarily focusedon an S-band frequency large deployablereflector (with an electric aperture of 13 m)that consists of 14 mesh reflector modules anda phased array feeder designed to generatemultiple beams; this feeder will incorporate agroup of solid-state amplifiers which synthe-size and produce 400-W (max.) high-outputpower in space, a beam-forming network(BFN) allowing emission of various types ofbeams in any direction over Japan and thevicinity, and a lightweight feed element offer-ing reduced cross-coupling between elements.(3) Communication mission systems

A multi-beam satellite communicationssystem requires an onboard switch to reducedelay in the satellite propagation path by con-necting any given two beams with a singlehop. In regenerative repeating, such a switchis also used to increase channel margin byseparating uplink noise from downlink noise.Thus our goal in the ETS-VIII project is todevelop a 1,000-channel onboard switch forsatellite voice communications and a high-

data-rate onboard packet switch for mobileterminals. In addition, we will develop an S-band converter equipment that can be config-ured flexibly to work as an experimentaltransponder and a Ka-band feeder link unitwith low phase noise performance.(4) High-precision time standard/comparison

equipmentThe ETS-VIII will feature a high-precision

time standard system (with an atomic clockand a signal generator transmitting a GPS-compatible signal) and a high-precision timecomparison system, the first such systems tobe deployed in Japan. These systems will per-mit in-orbit operation of the atomic clock,high-precision orbital determination, and pre-cise ground-satellite time comparison, and thetechnologies behind these operations willtogether form the foundation of future Japan-ese satellite positioning systems.(5) Upgrading ground stations

We plan to upgrade the Ka-band feederlink station (base station), develop the S-bandreference station, create ground terminalscompatible with the onboard switch, designvehicle-borne and other mobile stations, andestablish a range of additional ground-stationfacilities for both experimental and practicaluse.

In order to ensure that these systems aredeveloped efficiently, the ETS-VIII LiaisonCommittee has appointed a responsible organ-ization from either the CRL, JAXA, ASC, orNTT for each mission. Table 2 shows themajor development themes and its responsibleorganization.

In August 1999, JAXA, the CRL, the ASC,and NTT entered into the “Agreement on theDevelopment, Launch, and Operation ofMobile Communications/Broadcasting Exper-imental Instruments and High-Precision TimeExperimental Instruments for the EngineeringTest Satellite VIII,” in order to facilitate coop-eration among these groups. Additionally,“Interface Coordination Meetings” have beenheld at regular intervals to deal with variousissues related to the exchange of ideas amongthe relevant institutes, propose solutions to

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technological problems, and establish inter-face conditions for the devices in question.

After the ASC closed its R&D mission inFebruary 2001, the CRL assumed responsibili-ty for the systems the former group had devel-oped, with some revisions of its own to select-ed systems. In November 2002, all of the sys-tems developed by the CRL, the ASC, andNTT were handed over to JAXA for installa-tion in the satellite and the ground test before

launch.

4 Schedule for experiments

The goals of ETS-VIII experimentationare roughly classified as follows.(1) Evaluation of in-orbit performance of large

geostationary satellite bus and onboardsystemsWe will create projections of the in-orbit

Journal of the National Institute of Information and Communications Technology Vol.50 Nos.3/4 2003

Development themes for ETS-VIIITable 2

performance of the developed systems toexamine design validity, potential problems,and operability of practical future systems. Inso doing we must evaluate satellite perform-ance at appropriate intervals over a long peri-od of time, from initial checkout immediatelyafter launch through the end of the satellite’sservice life. Verification items will includethe basic properties of the satellite bus (e.g.,changes over time in generated power, per-formance of orbital and attitude maintenance,and onboard battery performance), basic per-formance of the large deployable reflector(including antenna pattern characteristics,accuracy of beam directivity, vibrations of theflexible structure, and thermal deformation),changes over time in the RF devices, and basicperformance of the onboard switch.(2) Basic communications experiments to

establish a next-generation mobile commu-nications technologyWe will evaluate the signal quality provid-

ed by the mobile satellite communicationssystem via the onboard switch, connectivitybetween multiple beams, propagation charac-teristics, and communications performance ofground stations and terminals under variousconditions (during walking, high-speed move-ment, interference, etc.). Through such exper-imentation, we will establish a fundamentaltechnology for next-generation mobile satel-lite communications technology, examine itsusefulness, and identify problems to be solvedprior to commercialization.(3) Experiments to establish the fundamental

technology of a future positioning systemJapan has never before installed an atomic

clock aboard a satellite. We are thereforeworking to develop the basic operational tech-niques for such an atomic clock and to estab-lish application technologies for high-preci-sion orbital determination and time compari-son. These efforts will, we believe, contributeto the realization of a future satellite-basedpositioning system.(4) Demonstrations and application experi-

mentsThrough demonstrations of basic mobile

satellite communications using the onboardswitch and multiple beams, we will promotethe usefulness of the next-generation mobilesatellite communications system, as we inves-tigate and promote a variety of mobile com-munication applications through applicationexperiments in cooperation with universities,research institutes, and private enterprises.

Fig.3 illustrates the organizational struc-ture behind this orbital testing. The Promo-tion Board for Satellite Application Experi-ments is hosted by the Space CommunicationsPolicy Division of the MPHPT, and its mem-bers are drawn from universities, researchinstitutes, and various industry organizations.It organizes the basic and application experi-ments, and evaluations of the ETS-VIII and ofan ultra-high speed Internet satellite, amongothers. Basic experiments to be conducted bythe satellite development organizations, andapplication experiments performed by theApplication Experiment Council participatedin by universities, research institutes, and pri-vate enterprises will first be subject toapproval by the Promotion Board. In addition,the Board will hold a liaison meeting to allowthe various groups to schedule basic and appli-cation experiments.

In experiments using the ETS-VIII, thesatellite development organizations—theCRL, JAXA, and NTT—will carry out basicexperiments (1) to (3), while members ofexternal organizations forming the ApplicationExperiment Council will carry out the applica-tion experiments described in (4). Twenty-two such application experiments were pro-

HAMAMOTO Naokazu et al. 9

Organization structure for promotingexperiments

Fig.3

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posed from October to December, 2002 bydomestic and overseas universities, researchinstitutes, and private enterprises in responseto a call for public participation by the Promo-tion Board for Satellite Application Experi-ments.

5 Conclusions

As described earlier, the development ofETS-VIII took place over six years, from the1992 conceptual design through approval bythe Space Activity Committee, and alreadyfive years have passed since the initiation offull-scale development. Although this satelliteproject represented a cutting-edge undertakingwhen first planned, subsequently a number offoreign countries have commercialized satel-lite-based cell-phone systems, some involvingLEO satellites (beginning in the U.S. with theIridium in 1998 and the Globalstar in 2000)and some employing a geostationary satelliteand a large deployable reflector (Garuda ofIndonesia in 2000, Thuraya of the United ArabEmirates in 2001). Additionally, due to thedelay in rocket development due to the fail-ures of the H-IIA, some ETS-VIII technolo-gies can no longer be viewed as innovative.

Nevertheless, a number of innovative ele-ments remain unique to the current project: thelarge deployable reflector of module structuredesigned for next-generation mobile satellitecommunications, multi-beam technology

capable of directing two or more beams to dif-ferent directions simultaneously, an onboardswitch for voice communications based onregenerative repeating, a packet switch forhigh-speed data communications, and a high-precision time comparison system enablingnovel applications of the onboard atomicclock. Moreover, establishment of a three-ton-class large geostationary satellite bus andthe development of techniques for in-orbitoperations of the atomic clock are expected toplay an important role in the creation of aninfrastructure for future satellite communica-tions, broadcasting applications, and position-ing systems. Further, a variety of additionaltechnologies have emerged through the devel-opment of the ETS-VIII, including those relat-ing to ground station facilities (such as mobilestations and terminals) and to a number ofonboard systems. These technologies areexpected to contribute greatly to future satel-lite development in the industrial sector.

Development of the ETS-VIII is nowapproaching the final stages in preparation forthe 2004 launch, with subsequent in-orbitexperimentation after launch expected to pro-duce significant results. It is clear that theprogress made thus far is the result of tremen-dous efforts on the part of those involved inthe project from the start—in industry, acade-mia, and in the government—to tackle thechallenges posed by this ambitious undertak-ing.

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References1 S. Yoshimoto, "Role of GEO Satellite System in Mobile Communications – S-band Mobile Communications

Sound Broadcasting Mission in ETS-VIII – ", Technical Report of IEICE, SANE97-120, pp.23-30, Jan. 1998.

2 K. Yonezawa, M. Homma, S. Yoshimoto, S. Hama, T. Ohira, N. Natori, and Y. Tsutsumi, "Outline of Engin-

nering Test Satellite VIII", 21st International Symposium on Space and Tech. and Sci., ISTS 98-h-01V,

Omiya, May, 1998.

3 Y. Kawakami, S. Yoshimoto, Y. Matsumoto, T. Ohira, and N. Hamamoto, "S-band Mobile Satellite Commu-

nications and Sound Broadcasting System in ETS-VIII", 21st International Symposium on Space and Tech.

and Sci., ISTS 98-h-02, Omiya, May, 1998.

HAMAMOTO Naokazu et al. 11

HAMAMOTO Naokazu

Research Supervisor, Wireless Commu-nications Division

Satellite Communication Engineering

IMAE Michito

Leader, Time and Frequency Measure-ments Group, Applied Research andStandards Division (present NationalInstitute of Advanced Industrial Scienceand Technology)

Frequency Standard, especially on Pre-cise Time Transfer

YOSHIMOTO Shigetoshi

Head, Public Relations Office, Strate-gic Planning Division (present Direc-tor, NICT Asia Research Center)

Satellite Communication Engineering

12 Journal of the National Institute of Information and Communications Technology Vol.50 Nos.3/4 2003