Journal of Global Positioning Systems (2004)
Vol. 3, No. 1-2: 259-264
Japanese Regional Navigation Satellite System “The JRANS Concept”
Hideto (Duke) Takahashi
ITOCHU Corporation, 2-5-1, Kita Aoyama, Minato-ku, Tokyo 107-8077, Japan
Received: 15 Nov 2004 / Accepted: 3 Feb 2005
Abstract. Current Global Navigation Satellite Systems
(GNSS) have enabled quality of life improvements and
new business opportunities on an international scale. The
range of applications and improvements includes a
multitude of disciplines such as Agriculture,
Transportation, Recreation, Public Safety and Security.
Independent financial institutions have estimated the
annual business market value for GNSS user equipment
and related components in the billions of US dollars. The
Government of Japan recognizes the importance of
investing in GNSS today to establish a foundation for
future quality of life improvements and business
opportunities for current and future generations. The
current Japanese program QZSS—Quasi Zenith Satellite
System with 3 GPS-supplementary satellites—represents
a bold step in the development of a Regional Navigation
Satellite System (RNSS) for all of Asia. In January 2004,
the Council for Science and Technology Policy (CSTP)
in the Cabinet Office published a report regarding the
future outlook of RNSS in Japan. This paper provides an
update on QZSS progress, the real-world challenges and
demands facing Japanese decision makers as reflected in
the CSTP report, and a glimpse into the future options for
the expansion of 3-satellite QZSS to a 7-satellite
constellation system that can autonomously provide
satellite-based position, velocity and time services, while
preserving the reciprocity and compatibility with the
GPS. In September 2004, CSTP published another report
regarding space policy that states a long-term goal of the
government to build the "autonomous" and "GPS-
complementary" regional satellite navigation system in
the future..
Key words: GPS, GNSS, QZSS, JRANS
1. Introduction
Japan, as well as many other countries, has been largely
dependent upon the US owned and operated Global
Positioning System (GPS) for obtaining space-based
position, velocity and time services.
In the 1970s, the US Department of Defense began GPS
development as a military force enhancer. In 1983,
President Reagan offered GPS civil services to the world,
free of direct charges, as a result of the KAL007 disaster.
This global offer sparked widespread civil use of GPS
and significant investment in civil GPS technologies, to
include GPS civil augmenting satellites (e.g. US Wide
Area Augmentation System (WAAS), European
Geostationary Navigation Overlay System (EGNOS) and
the Japanese Multi-functional Transport Satellite
(MTSAT)) and GPS civil user equipment to support a
broad range of applications from transportation to
agriculture.
From an International Civil Aviation Organization
(ICAO) perspective, ICAO document A32-19 establishes
and affirms the fundamental legal principles governing
the use of Global Navigation Satellite Systems (GNSS)
by ICAO contracting States. A key theme of A32-19 is
preservation of State authority and responsibility for the
provision of air navigation services in their sovereign
airspace. In other words, a State can approve GNSS for
navigation use in its sovereign airspace, but the State
retains authority and responsibility (and legal liability) for
the use of GNSS for navigation. Specific State
requirements are further clarified in principle number
four of A32-19. This principle specifically states that:
“Every State providing GNSS services…shall ensure the
continuity, availability, integrity, accuracy and reliability
of such services…including effective arrangements to
minimize the operational impact of system malfunctions
or failure and to achieve expeditious service recovery”.
GPS is becoming a mainstay of everyday life in Japan;
the Government of Japan (GOJ) is responsible for
providing air navigation services in sovereign airspace; it

260 Journal of Global Positioning Systems
is difficult to receive GPS signals in Japan due to
mountainous terrain, and tall buildings. These provided
incentives for the GOJ to investigate the practicality of
developing a standalone GPS-compatible system capable
of independently satisfying position, velocity and time
requirements for Japan and throughout the Asian region.
The remainder of this paper provides an overview of
some of the issues to be addressed, options considered,
decisions made, and highlights a future opportunity for
the Asian region.
2. Real-World Issues
2.1 Cost:
A regional solution for meeting Japanese position,
velocity and timing needs will require resources and
long-term investment.
The US has invested billons of dollars to design, develop
and implement a GPS "system". This investment goes
well beyond building and launching satellites. The
critical "brains" of GPS (the ground control segment with
its Master Control Station, Monitoring Stations, Control
Stations, Processors, Software, Communications,
Security, etc.) assures the satellites perform and the
"overall system" enables reliable position, velocity and
time within SPS specifications.
Then, there is the upfront and recurring cost of things that
are not generally seen, such as the papers and guidance
directions provided by the scientific community;
development of interfaces, compatibilities,
documentation, standardization, upgrades, training, etc.
The other critical cost dynamic is sustaining a space-
based system once it is operational. Replenishing
satellites, coordinating launcher availability, schedules,
risk mitigation (in the event of a launch failure), or an
anomalous event causing the disruption of satellite
signals. requires an enormous amount of planning,
knowledge, investment and most importantly experience.
2.2 Time Scale
GPS is being used today; as you read this paper, millions
of people throughout Japan and Asia are using GPS. This
use is growing on a daily basis. If Japan is going to
seriously consider fielding an independent GPS-
compatible system, then the system is needed as soon as
possible--not 10-15 years from now.
Once again, practical experience is critical to select the
best systems and subsystems, take advantage of approved
standards, documentation, international guidelines, and
employ proven risk mitigation techniques, etc. The net
result is that the time to field an independent GPS-
compatible system should be reduced.
It is well known that the GPS signals enable useable
services for a host of civil, as well as military
applications. In particular, GPS is also being relied upon
by the US and other countries as a foundation for aviation
navigation services.
2.3 Equipment Compatibility
GPS user equipment has a well established manufacturing
base. Those making GPS receivers and GPS "engines"
have the knowledge, experience and wherewithal to
provide useable equipment. If an independent GPS-
compatible Japanese system is going to be embraced and
provide benefits for all users, then user equipment must
be readily available and affordable.
If the manufacturers have to "invent" new user equipment
technology and components to accommodate a Japanese
regional system, there is an established process to support
the "invention" in Japan. Part of this process (particularly
for aviation applications) involves the development of
manufacturing standards and recommended practices.
Standards and recommended practices can literally take
years to develop and be accepted by the international
community. Standards and recommended practices,
associated research and development, testing, component
design, interfaces, etc. require investment on the part of
those manufacturers planning to produce user equipment.
These costs will be recovered by those manufacturers
producing the user equipment.
The net result of an "invention requirement" for GPS-
compatible Japanese user equipment: getting user
equipment to the marketplace will be delayed and
equipment will likely not be readily available; and GPS-
compatible Japanese user equipment costs will be
increased--likely higher than today's GPS equipment.
2.4 Opportunities
GPS was fully funded by the US Department of Defense
(DoD) and the US Department of Transport (DoT) to
satisfy position, velocity and time requirements as well as
"other" military missions. The point is that the
fundamental GPS ‘bus’ being used by the US DoD can
accommodate additional payloads besides the navigation
payload.

Takahashi: Japanese Regional Navigation Satellite System “The JRANS Concept” 261
Japanese GPS-compatible regional satellite system will
not necessarily have the same requirements as the US
DoD GPS satellites. This affords the opportunity to
explore the inclusion of other payloads on-board the
fundamental GPS ‘bus’--such as communication and
weather packages. These payloads could be used to
generate revenues to offset the overall cost to the GOJ for
the design, development, deployment, operation and
maintenance of a Japanese GPS-compatible regional
satellite system.
2.5 Ownership
Additional payloads and the opportunity to generate
revenue, begs the question regarding who should own and
operate a Japanese GPS-compatible regional satellite
system.
The US government owns and operates GPS. However, a
strong and practical argument can be made to allocate
ownership and operation of a Japanese GPS-compatible
regional satellite system to a commercial enterprise. This
argument is essentially business based--upfront
investment costs, revenue generation, return on
investments and overall system sustainment. Counter
arguments to the business based argument focus on
States' responsibilities, and subsequent liabilities as well
as continuity of the commercial enterprise. For instance,
should a Japanese GPS-compatible regional satellite
system be used to support aviation navigation, then
principle number four of A32-19 (described earlier)
applies.
However, it is quite possible that a cooperative
government-industry arrangement could be established in
order to accommodate Japanese government
responsibilities for assuring GNSS services while
offsetting government spending by taking advantage of
commercial investments.
3. Options
Real-world issues as highlighted in the previous section,
have established a path for the Japanese decision makers
to follow when formulating an approach for developing a
GPS-compatible Regional Satellite System capable of
serving Japan as well as all of Asia. The significance
and importance of these issues:
• Cost: initial and long-term commitments
• Time: GPS is here today--we need an
independent and complementary system now
• Compatibility: GPS is being used today, more
of the same is better and smarter
• Opportunities: GPS is a bus--it can carry other
payloads
• Ownership: government, industry or both--it is a
question.
were viewed differently by Japanese government and
industry representatives. These differences of opinion had
a positive effect because they resulted in several program
options for a Japanese GPS-compatible regional satellite
system. In the end, these options provided a basis for
moving forward with a comprehensive Japanese program.
A brief overview of two viable options will be provided
prior to discussing the current status of the Japanese
program.
Option A: Japanese Regional Navigation Satellite
System (JRANS)
In September 2000, the JRANS concept was developed
by a Japanese industry partnership of ITOCHU
Corporation, NEC Corporation and TOSHIBA
Corporation. JRANS conceptual briefings were provided
to several Japanese government representatives as well as
US government and industry personnel working with
GPS.
Based on the positive feedback from these initial
briefings, ITOCHU and NEC TOSHIBA Space Systems,
Ltd. (“NTSpace”, a joint venture between NEC and
TOSHIBA formed in April 2001 to merge their
respective space business) continued working and
discussing the JRANS concept with Japanese and US
government and industry personnel. The JRANS concept
and developmental approach was further refined to satisfy
current and future operational requirements and assure
full compatibility and interoperability with GPS.
Highlights of the JRANS concept are:
• Fully complementary, interoperability and
compatibility with GPS
• Capable of autonomous navigation and
complementary / regional backup for GPS
• Satellite coverage will be regional (i.e. over
Asia, see figure 1.)
• Free of direct user charges (like GPS)
• Private sector can participate and provide
commercial services
The proposed JRANS program is a two-phase build-up of
quasi-zenith (QZO), then another quasi-zenith and
geostationary orbiting satellites (QZO and GEO), see
figure 1.

262 Journal of Global Positioning Systems
Fig. 1a JRANS: PHASE 1--three Satellites Quasi-Zenith Orbit
For a satellite navigation receiver to calculate a solution,
four satellite signals in view with good geometry must be
received to determine latitude, longitude, altitude and
time. Satellite signals are “line-of sight” transmissions
and can be easily blocked by high terrain, buildings, etc.
This blocking of the signals is referred to as masking.
Use of GPS in Japan can be difficult because of this
masking situation. Natural geographic features, such as
mountainous terrain and manmade features, such as tall
buildings often render GPS services unavailable in the
most critical of situations.
The advantage of a fully populated (7 satellite)
constellation is having four satellites in view, at high
mask angles, broadcasting GPS-type information, being
controlled by Japan, and in coordination with the U.S.
under the bilateral security treaty.
Fig 1b JRANS: PHASE 2—four Satellites QZO and GEO
Having four Japanese GPS-compatible satellites in view
at higher elevations is particularly beneficial for those
operating in mountainous areas and "urban canyons", as
illustrated by Figure 2:
Fig 2: An example of masking in the urban canyon.
For GNSS users in Asia, there will also be a significant
improvement in overall end state user performance as a
result of better geometric dilution of precision (GDOP).
Recall, GDOP is all geometric factors that degrade the
accuracy of position fixes derived from externally
referenced navigation systems.

Takahashi: Japanese Regional Navigation Satellite System “The JRANS Concept” 263
Specifically, for a user in Tokyo Japan, using only GPS,
the GDOP for a 10 degree mask angle is 2.39; the GDOP
for a 30 degree mask angle is 6.88. That same user, at the
same location, using GPS and JRANS together would
have a GDOP of 1.80 at a 10 degree mask angle and a
GDOP of 3.59 with a 30 degree mask angle. Given that a
30 degree mask angle is typical for Japanese urban areas
(Figure 2), the improvement (from a GDOP of 6.88 with
GPS only to 3.59 with GPS and JRANS) will improve the
overall performance accuracy thereby increasing the
utility of satellite-based position, velocity and time.
Figure 3: GDOP: GPS Only
Figure 4: GDOP: GPS and JRANS
GDOP Scale
When one takes into consideration both JRANS signals
and GPS signals, the combined benefits for an end state
user--in terms of available satellite signals--are quite
significant, as illustrated in Figure 5:
Figure 5: Satellites in View
14
12
10 GPS+JRANS
8 GPS Only
6
4 JRANS
2
0
0 20 40 60 80
Mask Angle
Option B: Quasi-Zenith Satellite System (QZSS)
The QZSS option is actually the first phase of JRANS, as
mentioned above, three satellites in quasi-zenith orbit
(Figure 1).
In June 2002, the GOJ’s Council for Science and
Technology Policy of the Cabinet Office gave the go-
ahead to begin working on QZSS research and
development. The government role can be classified as
research and development. The plan is to design and
develop the first three QZSS satellites and the budget
(US$52M in FY2003 and US$77M in FY2004) has been
approved respectively. Several Japanese government
agencies are involved in this first phase, to include:
• MEXT (Ministry of Education, Culture, Sports,
Science and Technology): Experimental satellite
positioning technology
• MIC (Ministry of Internal Affairs and
Communications): Precise timing control and
communication
• METI (Ministry of Economy, Trade and
Industry): Key technologies for advanced satellite bus
• MLIT (Ministry of Land, Infrastructure and
Transportation): High-accuracy DGPS augmentation
system
A notional QZSS development schedule has been
prepared and is expected to be used for planning and
budgeting purposes. Overall, the GOJ is planning to
invest approximately JPY50B (US$450M) in research
and development funding for QZSS during the period
2003-2009. The notional schedule is:
• FY 2003: Definition Phase (US$52M budget
approved)

264 Journal of Global Positioning Systems
• FY 2004: Research & Development Phase
(US$77M budget approved)
• FY 2005-2008: Engineering & Manufacturing
Phase
• FY 2009: 1st Satellite Launch
From a commercial perspective, and in addition to the
basic navigation functions that will be fully compatible
with GPS, QZSS can provide communication services,
broadcasting services and differential GPS services. In
November 2002, in response to these commercial
opportunities, Japanese industry jointly formed the
Advanced Satellite Business Corporation (ASBC) to
conduct the feasibility study for determining the
opportunities of using QZSS to provide commercial
services, such as S-band communications and
broadcasting for mobile users.
4. Current Status
As indicated in the previous section, the GOJ has
committed resources to begin the design and development
of a GPS-compatible Regional Satellite System capable
of serving Japan as well as all of Asia. It is also evident
that the design and development road will be lengthy
without support from the US.
Both Japanese government and industry recognize the
importance of working cooperatively with US
government and industry. As early as April 2002,
ITOCHU and NTSpace have been making public
presentations in the US regarding Japanese planning
efforts and opportunities for US-Japanese government
and commercial cooperation.
From a government-to-government perspective, on 22
September, 1998 a US-Japan GPS partnership was forged
when President William Clinton and Prime Minister
Keizou Obuchi issued a joint statement regarding
cooperation in the use of the GPS standard positioning
service. Taking the statement, US-Japan GPS Plenary
Meetings have been held to further harmonize joint
activities. In addition, the Plenary agreed to form a Joint
Technical Working Group to further the close
cooperation between the US and Japan The Working
Group goals are essentially to:
• Assure maximum QZSS interoperability with
GPS
• Optimize the QZSS design to maximize GPS-
QZSS performance in Asia
• Increase commercial opportunities for GPS-
QZSS applications
5. Future Outlook for Asia
GPS reliance cannot be denied; neither can the
significance of GPS for a broad spectrum of Asian users.
In general, the aviation community appears to have a well
established set of performance requirements for satellite-
based navigation and are actively pursuing the
development and implementation of civil augmentation
systems. However, these "wide area coverage"
augmentation systems:
• US: Wide Area Augmentation Systems (WAAS)
• Europe: European Geostationary Navigation
Overlay System (EGNOS)
• Japan: MTSAT Satellite-base Augmentation
System (MSAS)
• India: GPS/GLONASS and Geostationary
Augmented Navigation (GAGAN)
• Australia: Ground-based Regional
Augmentation System (GRAS)
All have one thing in common: the US GPS. If GPS
signals "go away" then the utility of these augmentation
systems will be close to zero.
The Japanese government and industry personnel have
carefully studied the significance of GPS on our daily
lives, considered critical enabling issues, such as cost,
time, GPS compatibility, additional business
opportunities, and public / private ownership.
A decision was made to move forward with a GPS-
compatible regional system capable of providing
independent, satellite-based position, velocity and time
services while taking advantage of the broad range of
benefits available from GPS signals and the current GPS
industry..
For all of Asia, it is the most important fact that (in the
near future) a combined US GPS and a standalone
Japanese Regional Navigation Satellite System (RNSS)
will provide a robust foundation for current and future
generations of GPS users!