Mobile satellite service (MSS) has been under development in the United States for more than two decades. The service will soon be provided on a commercial basis by a consortium of eight U.S. companies called the American Mobile Satellite Consortium (AMSC). AMSC will build a three-satellite MSS system that will offer superior performance, reliability and cost effectiveness for organizations requiring mobile communications across the U.S. The development and operation of MSS in North America is being coordinated with Telesat Canada and Mexico. AMSC expects NASA to provide launch services in exchange for capacity on the first AMSC satellite for MSAT-X activities and for government demonstrations

Agnew, Carson E.

Bhagat, Jai

Exner, Michael L.

Hopper, Edwin A.

Kiesling, John D.

Melillo, Lawrence

Noreen, Gary K.

Parrott, Billy J.

English

NASA Technical Reports Server

N88-25758
MOBILE SATELLITE SERVICE IN THE UNITED STATES
DR. CARSON E. AGNEW, Hughes Communications Mobile Satellite Services, Inc.,
United States; JAI BHAGAT, MCCA Space Technologies Corporation, United States;
EDWIN A. HOPPER, McCaw Space Technologies, Inc., United States; JOHN D.
KIESLING, Mobile Satellite Corporation, United States; MICHAEL L. EXNER,
Skylink Corporation, United States; LAWRENCE MELILLO, North American Mobile
Satellite, Inc., United States; GARY K. NOREEN, Transit Communications, Inc.,
United States; BILLY J. PARROTF, Satellite Mobile Telephone Co., United States.
TRANSIT COMMUNICATIONS, INC.
P.O. Box 90425
Pasadena, California 91109-0425
United States
ABSTRACT
Mobile Satellite Service (MSS) has been under development in the
United States for more than two decades. The service will soon be
provided on a commercial basis by a consortium of eight U.S. compa-
nies called the American Mobile Satellite Consortium (AMSC). AMSC
will build a three-satellite MSS system that will offer superior perfor-
mance, reliability and cost effectiveness for organizations requiring
mobile communications across the U.S. The development and op-
eration of MSS in North America is being coordinated with Telesat
Canada and Mexico. AMSC expects NASA to provide launch services
in exchange for capacity on the first AMSC satellite for MSAT-X
activities and for government demonstrations.
INTRODUCTION
Mobile Satellite Service (MSS) will provide reliable mobile and thin-route com-
munications throughout the United States. MSS is uniquely suited to organizations with
geog.raphically dispersed operations and with requirements for ubiquitous com-
mumcatlons. MSS will be provided in this country by the American Mobile Satellite
Consortium (AMSC, 1988).
The AMSC MSS system has substantial advantages over alternative systems for
wide area mobile communications and position location. The system uses an SCPC ar-
chitecture that is flexible and that can address broad markets, resulting in economies of
scale. The system is well suited to fleet management applications, particularly where
flexibility and reliability are critical. It is also well suited to the support of public safety,
aviation safety, and resource exploration and development applications.
The Federal Communications Commission has determined that MSS will be pro-
vided in the United States by AMSC, which includes all eight qualified U.S. MSS appli-
cants (see Table 1). Each of the members of AMSC has placed $5 million in a joint es-
crow account. This $40 million joint account may be used for initial capitalization of the
consortium. AMSC filed a Joint Amendment to the applications of its eight members on
February 1, 1988 that describes its MSS system. The AMSC MSS system is also des-
cribed in a companion paper in this volume.
PRECEDING p._,GE _L_,NE ND_f FILW_ED 539
https://ntrs.nasa.gov/search.jsp?R=19880016374 2020-03-20T06:51:07+00:00Z
Table 1. American Mobile Satellite Consortium Participants
Hughes Communications Mobile Satellite Services, Inc.
P.O. Box 92424
Los Angeles, California 90009
Phone: (213)607-4000
North American Mobile Satellite, Inc.
733 Third Avenue
New York, New York 10017
Phone: (212)355-3440
MCCA Space Technologies Corporation
1500 Capital Towers
Jackson, Mississippi 39201
Phone: (601)969-1500
Satellite Mobile Telephone Co.
57 East 1lth Street
New York, New York 10003
Phone: (212)460-5022
McCaw Space Technologies, Inc.
409 S.W. 9th Avenue
Portland, Oregon 97205-3208
Phone: (503)243-3333
Skylink Corporation
1800 30th Street
Boulder, Colorado 80301
Phone: (303)442-8866
Mobile Satellite Corporation
65 Valley Stream Parkway, Suite 110
Malvern, Pennsylvania 19355
Phone: (215) 640-9660
Transit Communications, Inc.
P.O. Box 90425
Pasadena, California 91109-0425
Phone: (818) 577-8720
Telesat Canada, the designated Canadian MSS operator, and AMSC plan to de-
velop, produce and operate closely coordinated satellite and ground systems. Joint
implementation of the space segment eliminates the need for separate in-orbit spare satel-
lites, since the Telesat and AMSC systems can back up each other. Further savings will
be achieved in the ground segment by producing similar Network Operations and TT&C
centers to operate the Telesat and AMSC mobile satellite systems. These ground facilities
will then provide mutual backup.
The mutual backup of both the space and ground segments between Telesat and
AMSC assures high system reliability. Communications between a fleet controller and
mobiles can be relayed directly through the satellite, circumventing terrestrial links entirely
and ensuring continuity of communications during disasters.
In studies and experiments over the past two decades, NASA has demonstrated all
technical concepts necessary for mobile communications by satellite (ATS 1971-1982).
AMSC looks forward to close cooperation with NASA as it implements its system.
NASA has offered to provide launch services to AMSC in return for use of some of the
capacity of the first generation mobile satellite system (NASA, 1985). NASA would use
this capacity to perform technology experiments and to enable government agencies to as-
sess the usefulness of MSS to their operations. Government applications include public
safety, aviation safety, communications for wide and remote area coverage (police and
border control), monitoring of hazardous material transport, and others. Two years after
launch, NASA will return this capacity to AMSC. NASA includes a reservation for the
AMSC launch in its current ELV manifest.
AMSC SERVICES
AMSC will provide a comprehensive "generic" mobile satellite service, providing
economical services to land, maritime and aeronautical users. Through the use of a com-
mon space segment to provide all three classes of service, economies of scale are achieved
that have prevented implementation of land or aeronautical mobile satellite services in the
past.
AMSC will provide four basic services through its mobile satellite system:
540
• Mobile Telephone (interconnected with the public switched tele-
phone network)
• Mobile Radio (dispatch), including voice and data services
• Aeronautical Service
• Transportable Telephone Service
Taken together, the potential market for these mobile satellite services is quite large.
Market studies indicate that there is sufficient potential demand for these four basic ser-
vices, beyond that which terrestrial systems could reasonably or economically satisfy, to
fill the capacity of the AMSC mobile satellite system several times over (AMSC, !988).
AMSC anticipates supporting other, ancillary services as well. These potential ser-
vices include point-to-multipoint data distribution, paging, remote data collection, position
location and new mobile services using alphanumeric terminals.
Land Mobile
The primary class of mobile satellite service for which AMSC perceives an unfilled
need is communications for land vehicles over long ranges or in lightly populated areas.
Land mobile satellite service applications for which substantial demand has been estab-
lished include (AMSC, 1988):
• Rural Mobile Telephone and Radio
• Rail Mobile Telephone
• Interstate Trucking
• Mobile Paging/Dispatch
• Commercial Forest Services
• Emergency Services
• Government Services, including:
Public Safety (law enforcement, fire fighting, disaster manage-
ment, search & rescue, and rural health)
Forest Service
Customs and Immigration
Aviation
The aviation community, through the Federal Aviation Administration (FAA) and
the Canadian Department of Transportation (DOT), is now assessing its long range needs
for aeronautical services (FAA, 1985). Those requirements include operational and pas-
senger communications. Approximately 10% of the United States major air carrier fleet
now provides terrestrial based passenger telephone service.
Satellites offer the only economically viable technology to serve certain aviation
market requirements. The most important of the aeronautical services to be supplied by
AMSC are those related to the safety and regularity of flight, the AMSS(R) services.
While these services are of paramount importance, they do not require the full capacity of
the system and cannot economically support a satellite system on their own. By sup-
porting land, maritime and aeronautical mobile satellite services, a mobile satellite operator
can build a system providing the lowest cost service to all users.
Maritime Services
Although inland and coastal marine vessels now enjoy a variety of communications
options, many marine communications requirements remain inadequately addressed. For
example, commercial operators of vessels operating over long routes through inland and
541
coastal waterways face substantially the same fleet management requirements and prob-
lems faced by interstate trucking. Indeed, the same safety and competitive pressures are
at work in the marine freight transportation industry which drive the need for wide area
private networks.
Transportable Services
Other services which the AMSC system can ably provide are characterized by a
need for wide area coverage and long range or remote operation without the requirement
that they operate from moving vehicles. These may be termed "transportable" because
they typically involve transporting a portable terminal to the site where it will be used.
Rural telephone service, for those who can obtain it, has traditionally been expen-
sive despite the telephone companies' high degree of subsidization by revenue generated
from urban residential and business users. The high price is due to low subscriber densi-
ties (less than five subscribers per square mile). In addition, the very long local loops
which are required to provide this service can have a significant impact on cost.
Despite these high costs in the past, the cross-subsidization of rural local loops re-
stricted technological innovation. Now, deregulation of the telecommunications industry
and other regulatory developments are reducing or eliminating the revenue sources that
provided past subsidies. MSS will supplement existing and developing terrestrial tech-
nologies in the provision of ubiquitous rural telephone service.
In addition to rural voice telephone service, the gathering of data for production
control, monitoring, and planning purposes at oil and gas wells, on natural gas and other
pipelines, and electric utility remote transmission and distribution facilities can often only
be effectively supported through a satellite service. The AMSC system will be especially
attractive for these data transmission requirements because it can economically support
low capacity transportable terminals.
Other activities with similar requirements include aeronautical navigation aid moni-
toring, flood control, and water management at dams, remote weather and forest fire ob-
servation stations, seismic monitoring, and remote security systems.
ALTERNATIVE SYSTEMS
Terrestrial Systems
The predominant methods of land mobile communications currently include cellular
radio telephone service, Specialized Mobile Radio (SMR), and private networks. While
each of these services, within their current geographical areas, provide users with a reas-
onable level of service, there are limitations of each upon which MSS can improve.
The economic feasibility of all terrestrial based mobile systems is sensitive to sub-
scriber density. At lower densities, MSS will be more economical than terrestrial ser-
vices. MSS also offers improved service in areas difficult to serve because of rough ter-
rain. Moreover, MSS offers private network users distinct advantages when large areas
of coverage are required. For example, the AMSC MSS system is independent of any
ground network, and is thus not susceptible to terrestrial disasters.
Satellite Systems
Two satellite systems have been proposed as early alternatives to MSS: the Omninet
"Omnitracs" system (Omninet, 1987) and the Geostar Radiodeterminmion Satellite Service
(RDSS) system (Geostar, 1985).
Only the AMSC mobile satellite system can provide voice services. AMSC will
also provide data and positioning services much more effectively than any alternative.
542
Satellite-based systems, if properly designed, are not susceptible to disruptions in
the terrestrial network caused by local disasters. This makes them particularly attractive
for applications which require high reliability and which must count on immediate access
in emergencies. Of the satellite systems now under development, only the AMSC system
can circumvent the terrestrial network through the use of base stations at private control
centers. Also, only AMSC will have backup capacity available on both the ground and in
space. Thus, only the AMSC MSS system is satisfactory for applications in which full
redundancy and independence of terrestrial links is critical.
Also, the AMSC system will cost substantially less for subscribers than the Omni-
tracs and Geostar systems. Omnitracs requires complex, expensive K u band terminals
and uses K u band transponder capacity inefficiently. RDSS is inherently more expensive
to provide than MSS because of the need for extra satellites for triangulation measure-
ments, the need for separate transmit and receive antennas on mobiles and the inability to
aggregate services through a common satellite (precluding economies of scale).
Table 2 compares mobile communications and position location alternatives.
Table 2. Mobile Communications and Position Location Comparison
System MSS Cellular SMR Private Omnitracs 1 RDSS 2
Coverage
Voice
Base Stations
Redundant
Ground Segment
Mobile Antennas
Position Location
North America Local Local Local U.S. U.S.
Yes Yes Yes Yes No No
Yes No No Yes No No
Yes No No No No No
1 1 1 1 1 2
Yes 3 No No No No 4 Yes
1 Omninet has not been authorized to provide service.
2 RDSS has been authorized to provide only position messaging and ancillary messaging. It is not au-
thorized to provide communications services.
3 MSS can determine position through use of satellite ranging or integrated MSS/GPS transceivers.
4 Omnitracs uses Loran-C receivers for position location.
ACKNOWLEDGEMENTS
Richard Cooperman of Mobile Satellite Corporation, Dr. Teresa Ferguson of
Hughes Communications, Inc. and Glenn E. Noreen of Transit Communications, Inc.
made significant contributions to this paper.
REFERENCES
AMSC, 1988. Joint Amendment of the American Mobile Satellite Consortium, filed at
the Federal Communications Commission, February 1, 1988.
ATS, 1971-1982. Numerous MSS experiments were conducted with NASA's ATS-1
through -6 satellites. See General Electric Company ( 1971) Final Report on Phases
1 and 2 VHF Ranging and Position Fixing using ATS Satellites, prepared by Gen-
eral Electric Company Corporate Research and Development, Schenectady, New
York for Goddard Space Flight Center, Greenbelt, Maryland, May 1, 1971, Con-
543
tract No. NAS5-11634, NASA-CR-125538; Boeing Aircraft Company (1973),
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Mobile satellite service in the United States

Mobile satellite service in the United States

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