Signal Processing Approaches to Secure Physical Layer Communications in Multi-Antenna Wireless Systems

142 Pages·2014·3.54 MB·English

by  Y.-W. Peter Hong

SPRINGER BRIEFS IN ELECTRICAL AND
COMPUTER ENGINEERING  SIGNAL PROCESSING
Y.-W. Peter Hong  Pang-Chang Lan
C.-C. Jay Kuo
Signal Processing
Approaches to
Secure Physical Layer
Communications
in Multi-Antenna
Wireless Systems
SpringerBriefs in Electrical and Computer
Engineering
Signal Processing
Series Editors
Woon-Seng Gan, Singapore
C.-C. Jay Kuo, Los Angeles, USA
For furthervolumes:
http://www.springer.com/series/11560
Y.-W. Peter Hong Pang-Chang Lan
•
C.-C. Jay Kuo
Signal Processing
Approaches to Secure
Physical Layer
Communications
in Multi-Antenna
Wireless Systems
123
Y.-W. Peter Hong C.-C.Jay Kuo
Department of ElectricalEngineering Department of ElectricalEngineering
National TsingHuaUniversity Universityof SouthernCalifornia
Hsinchu Los Angeles, CA
Taiwan,R.O.C. USA
Pang-Chang Lan
Department of ElectricalEngineering
Universityof SouthernCalifornia
Los Angeles, CA
USA
ISSN 2196-4076 ISSN 2196-4084 (electronic)
ISBN 978-981-4560-13-9 ISBN 978-981-4560-14-6 (eBook)
DOI 10.1007/978-981-4560-14-6
SpringerSingaporeHeidelbergNewYorkDordrechtLondon
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(cid:2)TheAuthor(s)2014
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To my beloved family
—Peter
Dedicated to my parents
—Pang-Chang
In memory of my beloved father
—Jay
Preface
Physical layer secrecy has received much attention in recent years, especially in
wireless communications, due to the rapidly increasing data traffic and high
demand for ubiquitous connectivity. Different from conventional cryptographic
approachesusedtoaddresswirelesssecurityissues,physicallayersecrecyutilizes
channelcodingandsignalprocessingtechniquestocommunicatesecretmessages
between the source and the destination while maintaining confidentiality against
the eavesdropper. These studies originate from the information theory literature,
where the focus is often to determine the existence of channel codes that can
achievethistaskortoderivethefundamentallimitonthemaximumcoderatethat
can beapplied reliably under thesecrecy constraint(i.e.,the secrecy capacity).In
particular, information-theoretic results have shown that the secrecy capacity
increases with the difference between the reception quality at the destination and
that at the eavesdropper. Motivated by this result, signal processing approaches
have been developed in both the data transmission and channel estimation phases
to maximize the signal quality difference between the destination and the eaves-
dropper.Ingeneral,bothcodingandsignalprocessingaspectsoftheproblemmust
be taken into consideration in order to achieve the secrecy capacity. However,
when the optimal joint design is unknown, signal processing techniques can also
beusedtohelpincreasetheachievablesecrecyrateorreducethecomplexityofthe
channel coding operations. These approaches are especially interesting in multi-
antennawirelesssystems,wherethespatialdegreesoffreedomcanbeexploitedto
further enhance secrecy.
This book provides an overview of signal processing approaches that can be
used to enhance physical layer secrecy in multi-antenna wireless systems.
Specifically, in the data transmission phase, we review secrecy beamforming and
precoding techniques that can be used to not only strengthen the signal at the
destination, but also reduce the information leakage to the eavesdropper. We also
consider the use of artificial noise along with the transmission of the information
signal to further degrade the reception quality at the eavesdropper. Moreover, we
further extend the use of these techniques to distributed antenna or relay systems
wherethemultipleantennasmaynotbelocatedatasingleterminal.Theadditional
spatialdegreesoffreedomprovidemoredesignflexibilityandperformancegains,
but may also increase the security threats due to additional transmission required
for coordination among the distributed terminals and also due to the
vii
viii Preface
trustworthinessofsystemmembers.Intermsofchannelestimation,wereviewthe
so-called discriminatory channel estimation scheme which utilizes the design of
artificial noise aided training signals to increase the difference between the
effectivesignalqualityatthedestinationandthatattheeavesdropper.Inthiscase,
thedesiredsignalqualitydiscrepancyisenhancedevenbeforethetransmissionof
the confidential message and need only be done once every coherence interval
(instead of every symbol period).
This book is divided into 6 chapters. Chapter 1 introduces the importance and
challenge of achieving secrecy in wireless systems, and provides a brief mention
of the background on different notions of physical lay secrecy. Chapter 2 briefly
summarizes the basic results in information-theoretic secrecy. In Chapter 3,
secrecy beamforming and precoding designs along with the use of artificial noise
aredescribedaswaystoeffectivelyenhancethedesiredsignalqualitydiscrepancy
in the data transmission phase. In Chapter 4, these techniques are extended to
distributed antenna or relay systems. In Chapter 5, discriminatory channel esti-
mationschemesaredescribedasmethodstoachievesignalqualitydiscrepancyin
the channel estimation phase. Finally, in Chapter 6, several applications of
physical layer secrecy and their respective research directions are further
introduced.
The purpose of this book is to highlight the role of signal processing in
achieving secrecy in the physical layer, and to provide researchers and graduate
students, who are interested in pursuing research in this area, an overview of the
standardtechniquesknowntodayandabasicunderstandingofthechallengesthat
may arise in this area. We would like to remark that, due to the vast literature in
thisarea,itisnotpossibletogiveacomprehensivetreatmentofthematerialinthe
literature. However, we hope that the materials included in this book provide a
logical treatment of the basic results and allow researchers and graduate students
to gain sufficient knowledge to pursue research in this area.
Hsinchu, Taiwan, May 2013 Y.-W. Peter Hong
Los Angeles, USA, May 2013 Pang-Chang Lan
C.-C. Jay Kuo
Acknowledgments
This work was supported in part by the National Science Council, Taiwan, under
grant NSC 100-2628-E-007-025-MY3. The authors would also like to thank
Ta-Yuan Liu, Yu-Ching Chen, Li-Ren Chen, and Lin-Ming Huang for extensive
proof-reading of the manuscript.
ix
Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Security in Wireless Communication Systems. . . . . . . . . . . . . . 1
1.2 Background on Physical Layer Secrecy . . . . . . . . . . . . . . . . . . 3
1.2.1 Keyless Physical Layer Secrecy Transmissions. . . . . . . . 4
1.2.2 Channel-Based Secret Key Generation. . . . . . . . . . . . . . 5
1.2.3 Signal Designs with Low Probability of Interception
and Detection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.3 Book Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2 Background on Information-Theoretic Physical Layer Secrecy . . . 11
2.1 The Basic Wiretap Channel . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.2 Gaussian and MIMO Gaussian Wiretap Channels . . . . . . . . . . . 16
2.3 Compound Wiretap Channel. . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.4 Ergodic Secrecy Capacity. . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.5 Secrecy Outage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.6 Summary and Discussions . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3 Secrecy Precoding and Beamforming in Multi-Antenna
Wireless Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.1 Secrecy Beamforming and Precoding Schemes. . . . . . . . . . . . . 30
3.1.1 Secrecy Beamforming for the Basic Multi-Antenna
Wiretap Channel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.1.2 Secrecy Precoding for the Basic Multi-Antenna Wiretap
Channel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
3.2 Secrecy Beamforming for Systems with Multiple Destinations
and Eavesdroppers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
3.2.1 Multicast Secrecy Beamforming. . . . . . . . . . . . . . . . . . 38
3.2.2 Broadcast Secrecy Beamforming. . . . . . . . . . . . . . . . . . 40
3.3 Secrecy Beamforming and Precoding with Artificial Noise. . . . . 43
3.3.1 Secrecy Beamforming with Artificial Noise. . . . . . . . . . 44
3.3.2 Power Allocation Between Information Signal
and Artificial Noise. . . . . . . . . . . . . . . . . . . . . . . . . . . 48
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xii Contents
3.3.3 Secrecy Precoding with Artificial Noise. . . . . . . . . . . . . 52
3.4 Secrecy Beamforming with Artificial Noise for Systems
with Multiple Destinations and Eavesdroppers . . . . . . . . . . . . . 56
3.5 Summary and Discussions . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
4 Distributed Secrecy Beamforming and Precoding
in Multi-Antenna Wireless Relay Systems. . . . . . . . . . . . . . . . . . . 61
4.1 Distributed Secrecy Beamforming and Precoding
with Trusted Relays. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
4.1.1 Distributed Secrecy Beamforming and Precoding
with Trusted Decode-and-Forward Relays . . . . . . . . . . . 63
4.1.2 Distributed Secrecy Beamforming and Precoding
with Trusted Amplify-and-Forward Relays. . . . . . . . . . . 71
4.2 Distributed Secrecy Beamforming and Precoding
with Untrusted Relays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
4.3 Distributed Secrecy Beamforming and Precoding
with Artificial Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
4.3.1 Relays as Pure Cooperative Jammers. . . . . . . . . . . . . . . 83
4.3.2 Relays with Both Information and Artificial
Noise Transmissions . . . . . . . . . . . . . . . . . . . . . . . . . . 88
4.4 Summary and Discussions . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
5 Secrecy-Enhancing Channel Estimation in Multi-Antenna
Wireless Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
5.1 Feedback-and-Retraining Discriminatory Channel
Estimation Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
5.2 Two-Way Training Discriminatory Channel
Estimation Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
5.2.1 Two-Way DCE Scheme for Reciprocal Channels . . . . . . 108
5.2.2 Two-Way DCE Scheme for Nonreciprocal Channels. . . . 114
5.3 Summary and Discussions . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
6 Enhancing Physical-Layer Secrecy in Modern Wireless
Communication Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
6.1 Secrecy in Cognitive Radio Networks . . . . . . . . . . . . . . . . . . . 125
6.2 Secrecy in OFDM and OFDMA Systems. . . . . . . . . . . . . . . . . 128
6.3 Secrecy in Ad Hoc and Multihop Networks . . . . . . . . . . . . . . . 129
6.4 Secrecy in Cellular Networks . . . . . . . . . . . . . . . . . . . . . . . . . 131
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133