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The Evolution Of Untethered
Communications
Committee on Evolution of Untethered
Communications
Computer Science and Telecommunications Board
Commission on Physical Sciences, Mathematics, and
Applications
National Research Council
NATIONAL ACADEMY PRESS
Washington, D.C. 1997
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Page ii
NOTICE: The project that is the subject of this report was
approved by the Governing Board of the National Research Council,
whose members are drawn from the councils of the National Academy
of Sciences, the National Academy of Engineering, and the Institute
of Medicine. The members of the committee responsible for the
report were chosen for their special competences and with regard
for appropriate balance.
This report has been reviewed by a group other than the authors
according to procedures approved by a Report Review Committee
consisting of members of the National Academy of Sciences, the
National Academy of Engineering, and the Institute of Medicine.
The National Academy of Sciences is a private, nonprofit,
self-perpetuating society of distinguished scholars engaged in
scientific and engineering research, dedicated to the furtherance
of science and technology and to their use for the general welfare.
Upon the authority of the charter granted to it by the Congress in
1863, the Academy has a mandate that requires it to advise the
federal government on scientific and technical matters. Dr. Bruce
Alberts is president of the National Academy of Sciences.
The National Academy of Engineering was established in 1964,
under the charter of the National Academy of Sciences, as a
parallel organization of outstanding engineers. It is autonomous in
its administration and in the selection of its members, sharing
with the National Academy of Sciences the responsibility for
advising the federal government. The National Academy of
Engineering also sponsors engineering programs aimed at meeting
national needs, encourages education and research, and recognizes
the superior achievements of engineers. Dr. William A. Wulf is
president of the National Academy of Engineering.
The Institute of Medicine was established in 1970 by the
National Academy of Sciences to secure the services of eminent
members of appropriate professions in the examination of policy
matters pertaining to the health of the public. The Institute acts
under the responsibility given to the National Academy of Sciences
by its congressional charter to be an adviser to the federal
government and, upon its own initiative, to identify issues of
medical care, research, and education. Dr. Kenneth I. Shine is
president of the Institute of Medicine.
The National Research Council was organized by the National
Academy of Sciences in 1916 to associate the broad community of
science and technology with the Academy's purposes of furthering
knowledge and advising the federal government. Functioning in
accordance with general policies determined by the Academy, the
Council has become the principal operating agency of both the
National Academy of Sciences and the National Academy of
Engineering in providing services to the government, the public,
and the scientific and engineering communities. The Council is
administered jointly by both Academies and the Institute of
Medicine. Dr. Bruce Alberts and Dr. William A. Wulf are chairman
and vice chairman, respectively, of the National Research
Council.
Support for this project was provided by the Defense Advanced
Research Projects Agency. Any opinions, findings, conclusions, or
recommendations expressed in this material are those of the authors
and do not necessarily reflect the views of the sponsors.
Library of Congress Catalog Card Number 97-80464
International Standard Book Number 0-309-05946-1
Copyright 1997 by the National Academy of Sciences. All rights
reserved.
Additional copies of this report are available from:
National Academy Press
2101 Constitution Ave., NW
Box 285
Washington, DC 20055
800-624-6242
202-334-3313 (in the Washington metropolitan area)
http://www.nap.edu
Printed in the United States of America
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Page iii
COMMITTEE ON EVOLUTION OF UNITHERED COMMUNICATIONS
DAVID J. GOODMAN, Rutgers University, Chair
NORMAN ABRAMSON, ALOHA Networks, Inc.
EUGENE CACCIAMANI, Hughes Network Systems
JOEL ENGEL, Ameritech
MARK EPSTEIN, QUALCOMM, Inc.
BRUCE FETTE, Motorola, Inc.
DOUGLAS C. FIELDS, United Parcel Service
BEZALEL GAVISH, Vanderbilt University
ANDREA GOLDSMITH, California Institute of Technology
RANDY H. KATZ, University of California at Berkeley
EDWIN A. KELLEY, Hughes Aircraft Company
KAVEH PAHLAVAN, Worcester Polytechnic Institute
CHARLES E. PERKINS, Sun Microsystems
THEODORE RAPPAPORT, Virginia Polytechnic Institute
JESSE RUSSELL, AT&T Laboratories
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COMPUTER SCIENCE AND TELECOMMUNICATIONS BOARD
DAVID D. CLARK, Massachusetts Institute of Technology,
Chair
FRANCES E. ALLEN, IBM T.J. Watson Research Center
JAMES CHIDDIX, Time Warner Cable
JEFF DOZIER, University of California at Santa Barbara
A.G. FRASER, AT&T Corporation
SUSAN L. GRAHAM, University of California at Berkeley
JAMES GRAY, Microsoft Corporation
BARBARA J. GROSZ, Harvard University
PATRICK M. HANRAHAN, Stanford University
JUDITH HEMPEL, University of California at San Francisco
DEBORAH A. JOSEPH, University of Wisconsin
BUTLER W. LAMPSON, Microsoft Corporation
EDWARD D. LAZOWSKA, University of Washington
MICHAEL LESK, Bellcore
DAVID LIDDLE, Interval Research
BARBARA H. LISKOV, Massachusetts Institute of Technology
JOHN MAJOR, QUALCOMM, Inc.
DAVID G. MESSERSCHMITT, University of California at Berkeley
DONALD NORMAN, Hewlett-Packard Company
RAYMOND OZZIE, Rhythmix Corporation
DONALD SIMBORG, KnowMed Systems
LESLIE L. VADASZ, Intel Corporation
MAJORY S. BLUMENTHAL, Director
HERBERT S. LIN, Senior Staff Officer
JERRY R. SHEEHAN, Program Officer
ALAN S. INOUYE, Program Officer
JON EISENBERG, Program Officer
MARK E. BALKOVICH, Research Associate
JANET BRISCOE, Administrative Associate
LISA L. SHUM, Project Assistant
SYNOD P. BOYD, Project Assistant
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Page v
COMMISSION ON PHYSICAL SCIENCES, MATHEMATICS, AND
APPLICATIONS
ROBERT J. HERMANN, United Technologies Corporation,
Co-chair
W. CARL LINEBERGER, University of Colorado, Co-chair
PETER M. BANKS, Environmental Research Institute of Michigan
WILLIAM BROWDER, Princeton University
LAWRENCE D. BROWN, University of Pennsylvania
RONALD G. DOUGLAS, Texas A&M University
JOHN E. ESTES, University of California at Santa Barbara
MARTHA P. HAYNES, Cornell University
L. LOUIS HEGEDUS, Elf Atochem North America, Inc.
JOHN E. HOPCROFT, Cornell University
CAROL M. JANTZEN, Westinghouse Savannah River Company
PAUL G. KAMINSKI, Technovation, Inc.
KENNETH H. KELLER, University of Minnesota
KENNETH I. KELLERMANN, National Radio Astronomy Observatory
MARGARET G. KIVELSON, University of California at Los
Angeles
DANIEL KLEPPNER, Massachusetts Institute of Technology
JOHN KREICK, Sanders, a Lockheed Martin Company
MARSHA I. LESTER, University of Pennsylvania
NICHOLAS P. SAMIOS, Brookhaven National Laboratory
CHANG-LIN TIEN, University of California at Berkeley
NORMAN METZGER, Executive Director
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Page vii
Preface
In 1994, the Defense Advanced Research Projects Agency (DARPA)
initiated the Global Mobile Information Systems (GloMo) program to
apply advances in high-speed computation, signal processing, and
miniaturization to mobile, wireless, multimedia information
systems. The GloMo program is intended to develop the technologies
that will enable military forces to carry out communication and
computing tasks free of tethers—that is, cables to power
sources or telecommunications networks. The concept of "untethered"
communications unites mobile and wireless operations.
In response to a request from DARPA, the Computer Science and
Telecommunications Board (CSTB) of the National Research Council
initiated a one-year study on untethered communications in July
1996. To carry out the study, the CSTB appointed a committee of 15
wireless-technology experts, including researchers, program
managers, technology developers, and users working in industry and
academia. The Committee on the Evolution of Untethered
Communications was charged with advising DARPA on where to invest
in information technology for mobile wireless systems. In
particular, DARPA posed the following questions:
•
What will industry do on its own? When?
•
What are the military requirements and needs in mobile wireless
information technology?
•
To what extent will commercial technology development support
military needs?
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Page viii
•
Where can DARPA have the greatest impact in technology
development or acceleration of technology development to support
the military?
This report presents the results of the CSTB study. In addition
to answering DARPA's questions, the report provides a wealth of
information of interest to a broader audience, suggesting that this
is an era of unprecedented change, growth, and promise in
untethered communications for both civilian and military users. The
report explores the evolution of wireless technology, the
often-fruitful synergy between commercial and military research and
development efforts, and the technical challenges still to be
overcome. Many examples of past ingenuity and future opportunities
in wireless systems are noted. Although much of the information can
be obtained piecemeal from other sources, it is rarely collected
and analyzed in the manner found here. This is the CSTB's first
report on wireless communications.
The committee met four times during the one-year study time
frame. The report is based on the committee's discussions with
representatives of military organizations and commercial
developers, background information from the literature, the
expertise and judgment of individual committee members, and the
deliberations of the committee as a group.
The committee appreciates DARPA's sponsorship of this project
and in particular acknowledges the participation of four
individuals. Howard Frank, former director of the Information
Technology Office, provided valuable advice to the CSTB prior to
the initiation of the study. Barry Leiner, the original driving
force behind the GloMo program, had the vision to appreciate how a
comprehensive technology assessment could complement the specific
research projects already under way. Kevin Mills, who later assumed
leadership of the GloMo program, addressed the committee at the
beginning of its study. Rob Ruth, who succeeded Mills, shared his
insights into operational military needs and encouraged the
committee and CSTB staff to support DARPA's needs to advance and
refine GloMo planning. All of these individuals provided regular
reminders of DARPA's strong interest in this study and helped
motivate the committee's efforts to develop a comprehensive
analysis that takes into account the context of military decision
making.
The committee also benefited enormously from the assistance of a
number of anonymous reviewers. Reviewer comments and constructive
criticisms helped the committee transform a voluminous early draft
into a tighter, well-organized final report, calibrate the emphasis
placed on a variety of topics, and clarify the analysis of specific
issues.
Finally, the committee appreciates the effort and energy devoted
to this project by former CSTB staff member Paul Semenza, who
organized the study and guided the writing and revision of this
report, and former
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Page ix
CSTB project assistant Gail Pritchard, who provided
administrative and logistical support. It also is grateful for the
yeoman efforts of Laura Ost, the writer-editor who worked with the
committee during the summer of 1997 to improve the organization and
written presentation of its ideas.
David Goodman, Chair
Committee on Evolution of
Untethered Communications
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Page xi
Contents
EXECUTIVE SUMMARY
1
1 PAST, PRESENT, AND FUTURE
10
1.1 Overview
11
1.2 Historical Perspective
13
1.2.1 Communications Before
the Industrial Age
13
1.2.2 Telegraphy
15
1.2.3 Early
Wireless
15
1.2.4 Telephony
16
1.2.5 Communications
Satellites
17
1.2.6 Mobile Radio and the
Origins of Cellular Telephony
18
1.2.7 The Internet and
Packet Radio
19
1.3 Military Wireless Systems
and Research
21
1.3.1 Terrestrial
Systems
21
1.3.2 Satellite Systems
24
1.3.3 Research Initiatives
in Untethered Communications
25
1.3.3.1 Global Mobile
Information Systems Program
26
1.3.3.2
Software-Defined Radio Research
28
1.3.3.3 Communications
Systems Research
29
1.3.3.4 Radio Component
Research
29
1.3.3.5 Small Unit
Operations
30
1.3.3.6 Modeling and
Simulation
30
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Page xii
1.4 Commercial Terrestrial
Mobile Telephone Systems and Services
30
1.4.1 First-Generation
Systems
31
1.4.2 Second-Generation
Systems
33
1.4.3 Third-Generation
Systems
38
1.5 Commercial Satellite
Systems
41
1.6 Mobile Data Services
44
1.7 Wireless Local Area
Networks
47
1.8 Comparison of International
Research, Development, and Deployment Strategies
47
1.9 Summary and Report
Organization
52
Notes
54
2 TECHNOLOGY LIMITS, TRADE-OFFS, AND
CHALLENGES
56
2.1 Communication Link
Design
58
2.1.1 Characteristics of
the Wireless Channel
60
2.1.1.1 Path Loss
60
2.1.1.2 Shadow
Fading
61
2.1.1.3 Small-Scale
(Multipath) Fading
62
2.1.1.4
Interference
63
2.1.1.5 Satellite
Channels
64
2.1.2 Capacity Limits of
Wireless Channels
64
2.1.3 Modulation
65
2.1.4 Channel Coding and
Link-Layer Retransmission
65
2.1.5 Countermeasures for
Fading
67
2.1.5.1 Flat-Fading
Countermeasures
67
2.1.5.2 Countermeasures
for Frequency-Selective Fading
69
2.1.6 Channel Access
72
2.1.6.1
Fixed-Allocation Multiple Access
72
2.1.6.2 Demand-Assigned
Multiple Access
73
2.1.6.3 Random
Access
74
2.2 Network Issues
75
2.2.1 Architecture
75
2.2.1.1 Cellular System
Design
76
2.2.1.2 Packet Radio
System Design
78
2.2.2 Physical Resource
Allocation
79
2.2.3 Interoperability
80
2.2.4 Routing and Mobility
Management
81
2.2.4.1 Multihop
Routing
81
2.2.4.2 Terminal
Mobility
82
2.2.4.3 Wireless
Overlay Networks
84
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Page xiii
2.2.5 Resource
Discovery
85
2.2.6 Network Simulation
and Modeling Tools
85
2.3 End-to-End System Design
Issues
86
2.3.1 Application-Level
Adaptation
86
2.3.2 Quality of
Service
87
2.3.2.1 Approaches to
Quality of Service
87
2.3.2.2 Transport-Layer
Issues
91
2.3.3 Security
92
2.4 Hardware Issues
94
2.4.1 Antennas
95
2.4.2 Other Radio
Components
97
2.4.2.1
Analog-to-Digital Converters
98
2.4.2.2 Digital Signal
Processors
99
2.4.2.3 Filters
100
2.4.2.4 Radio Frequency
Amplifiers
100
2.4.3 Portable Terminal
Design
101
2.4.3.1 Displays, User
Interfaces, and Input Devices
101
2.4.3.2 Processors
102
2.4.3.3 Batteries
102
2.4.3.4 Storage
103
2.5 Summary
103
Notes
104
3 COMMERCIAL-DEFENSE SYNERGY IN
WIRELESS COMMUNICATIONS
108
3.1 Overview
109
3.2 Motivations for
Commercial-Defense Synergy
111
3.2.1 Design Reuse
113
3.2.2 Production Learning
Curve
114
3.2.3 Maintenance and
Logistics Support
116
3.2.4 Training
117
3.2.5 Cycle Time
117
3.3 Barriers to
Commercial-Defense Synergy
119
3.3.1 Risks of Dependence
on Commercial Technologies
120
3.3.2 Trade-offs Between
Cost and Complexity
121
3.3.2.1 Performance
Issues
121
3.3.2.2 Quality and
Testing
122
3.3.3 Infrastructure
Differences
124
3.4 Designing Wireless Systems
for Military Applications
125
3.4.1 Network
Architecture
125
3.4.1.1 Network Design
Issues
125
3.4.1.2 Bandwidth
Requirements
129
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Page xiv
3.4.1.3 Source
Coding
131
3.4.1.4 Highly Adaptive
Systems
133
3.4.2
Security
134
3.4.2.1 Availability of
Service
135
3.4.2.2 Confidentiality and
Integrity
135
3.4.3 Multimode, Multiband
Communications
137
3.4.3.1 Software-Defined
Radios
138
3.4.3.2 Co-Site
Interference
139
3.5 Defense Technology Policy
Issues
141
3.5.1 Implications of Changes in
Military Tactics
141
3.5.2 Rapid Infrastructure
Deployment
142
3.5.3 Logistics
142
3.5.4 Preparing for
Unsophisticated Adversaries
143
3.5.5 Preparing for Sophisticated
Adversaries
144
3.6 Summary
144
Notes
145
4 CONCLUSIONS AND RECOMMENDATIONS
149
4.1 History and Challenges of
Wireless Communications
149
4.2 Standards Development
152
4.3 Demonstration and Testing Rather
Than Development
154
4.4 Procurement
155
4.5 Modeling and Simulation
156
4.6 Network Architecture
158
4.7 Network Security
159
4.8 High-Density Communications
Platforms
160
4.9 Software Radios
162
4.10 Smart Antennas
162
4.11 Smart Waveforms
163
4.12 Filter Technology
164
4.13 Novel Components
165
BIBLIOGRAPHY
167
APPENDIXES
A Biographies of Committee
Members
175
B Briefers to the Committee
180
C Glossary
182
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