resource allocation in ofdm-based relay and cognitive radio networks

221 Pages·2014·2.52 MB·English

RESOURCE ALLOCATION IN
OFDM-BASED
RELAY AND COGNITIVE RADIO NETWORKS
Shashika Lakmali Biyanwilage
A thesis submitted for the degree of
Doctor of Philosophy in Engineering
SCHOOL OF COMPUTING, ENGINEERING AND MATHEMATICS
UNIVERSITY OF WESTERN SYDNEY
AUSTRALIA
NOVEMBER 2013
⃝c Shashika Lakmali Biyanwilage, 2013
To my Parents and my beloved Husband
DECLARATION
Date: NOVEMBER 2013
Author: Shashika Lakmali Biyanwilage
Title: RESOURCE ALLOCATION IN OFDM-BASED RELAY AND
COGNITIVE RADIO NETWORKS
Degree: PhD
I certify that the work presented in this thesis is, to the best of my knowledge
and belief, original, except as acknowledged in the text, and that the material has not
been submitted, either in full or in part, for a degree at this or any other institution.
IcertifythatIhavecompliedwiththerules,requirements,proceduresandpolicy
relating to my higher degree research award of the University of Western Sydney.
Author’s Signature
Acknowledgements
First and foremost, I would like to express my sincere gratitude to my prin-
cipal supervisor, Dr. Ranjith Liyanapathirana, for providing me the invaluable
opportunity to pursue my PhD under his supervision. Successful completion of
this thesis would not have been possible without his expertise, guidance, and
feedback.
I extend my deepest gratitude to my co-supervisor, Dr. Upul Gunawardana,
for his excellent supervision and mentorship throughout my candidature. His
persistent support, motivation and indispensable feedback have been the key for
my research achievements.
I am grateful to the University of Western Sydney for granting me an In-
ternational Postgraduate Research Scholarship and an Australian Postgraduate
Award, without which this research study would not have been possible. I am
also thankful to the School of Computing, Engineering, and Mathematics for
providing travel assistance to attend national and international conferences.
I would like to thank all the technical sta(cid:27), general sta(cid:27) and academics of
School of Computing, Engineering, and Mathematics who directly or indirectly
helped me during my candidature. My gratitude also goes to all my colleagues for
their support, friendship and useful discussions. I specially thank Mr. Prasanna
Herath and Ms. Madhuka Jayawardhana for allowing me to access their PCs to
run my simulations.
I gratefully remember my Honours and Masters Degree Supervisor, Professor
Dileeka Dias of University of Moratuwa, Sri Lanka, for providing me with the
initiationtowardspursuingaresearchcareer. Iamalsogratefultoallmyteachers
and lecturers for their guidance which is the reason behind my success.
My sincere and heartfelt gratitude is deserved by my parents for their love,
encouragement and inspiration throughout my life. I owe all my achievements
to their unconditional support. I am also greatly indebted to my two sisters for
being supportive and caring whenever required.
Finally, and most importantly, I would like to thank my loving husband,
Lokitha Amarasena, who has been a shadow behind all my successes during the
lastseveralyears. Wordsfailmetoexpressmyappreciationforhisunderstanding,
patience and support throughout this period.
v
Abstract
Resource allocation methods are highly system dependent and speci(cid:28)c re-
source allocation methods should be tailored according to the respective system
speci(cid:28)cations and requirements. This thesis investigates new resource allocation
methods for OFDM-based relay and cognitive radio (CR) networks. Performance
of the proposed methods is veri(cid:28)ed through computer simulations. Firstly, re-
source allocation in multi-relay assisted cooperative OFDM networks is consid-
ered. Resource allocation problem is mathematically formulated to maximize the
instantaneous capacity. As an alternative for more complex jointly optimal re-
source allocation methods, less-complex yet e(cid:27)ective resource allocation methods
are proposed. Secondly, power allocation in OFDM-based two-hop relay networks
is studied in the presence of outdated channel knowledge. Two new power allo-
cation methods are discussed to maximize the expected rate and the outage rate.
Thirdly, relay selection and power allocation in OFDM-based CR relay networks
isstudiedtomaximizetheinstantaneouscapacityoftheCRtransmission. Subop-
timal resource allocation methods are presented for multi-relay assisted OFDM
CR networks and their performance is compared with jointly optimal resource
allocation method. Next, new resource allocation methods are presented to max-
imize the instantaneous capacity of CR relay networks when only the statistical
channel information between the CR network and the legacy network is known.
Optimal power allocation methods to maximize the instantaneous capacity of the
CR transmission are derived and low complexity suboptimal power allocation al-
gorithmsarealsoproposed. Finally,apracticalscenarioofoperatingCRnetworks
in TV white spaces is considered. An interference minimization based power al-
location method is developed for OFDM-based single-hop CR transmission. Nu-
merical results con(cid:28)rm that the proposed power allocation scheme produces less
interferencetoTVreceiverscomparedtootherclassicalpowerallocationmethods
while guaranteeing an acceptable quality of service for secondary transmission.
Contents
Abstract v
Contents vi
Abbreviations xi
Notation xiii
List of Figures xiv
List of Publications xviii
1 Introduction 1
1.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Major Contributions . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.3 Thesis organization . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2 Literature Review 10
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.2 Relay Communication . . . . . . . . . . . . . . . . . . . . . . . . 10
2.3 Diversity Reception . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.4 Cooperative Communication . . . . . . . . . . . . . . . . . . . . . 12
2.5 Protocols for Cooperative Communication . . . . . . . . . . . . . 15
2.5.1 Amplify-and-Forward Method . . . . . . . . . . . . . . . . 15
CONTENTS vii
2.5.2 Decode-and-Forward Method . . . . . . . . . . . . . . . . 17
2.6 Fixed and Adaptive Relaying . . . . . . . . . . . . . . . . . . . . 17
2.6.1 Selection Relaying . . . . . . . . . . . . . . . . . . . . . . 18
2.6.2 Incremental Relaying . . . . . . . . . . . . . . . . . . . . . 19
2.7 Orthogonal Frequency Division Multiplexing . . . . . . . . . . . . 19
2.8 Orthogonal Frequency Division Multiple Access . . . . . . . . . . 22
2.9 Cooperative OFDM Networks . . . . . . . . . . . . . . . . . . . . 24
2.10 Cognitive Radio . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.10.1 OFDM for Cognitive Radio . . . . . . . . . . . . . . . . . 30
2.11 Cooperative Relaying in OFDM-Based Cognitive Radio Networks 30
2.11.1 OFDM Cognitive Wireless Relay Networks . . . . . . . . . 31
2.12 Resource Allocation in Wireless Networks . . . . . . . . . . . . . 33
2.12.1 Resource Allocation in Cooperative OFDM Networks . . . 34
2.12.2 Resource Allocation in OFDM Cognitive Wireless Relay
Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
2.12.3 Resource Allocation for Rate Maximization . . . . . . . . . 37
2.13 Optimization Techniques for Resource Allocation . . . . . . . . . 39
2.14 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
3 Resource Allocation in Cooperative OFDM Networks 44
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
3.2 System and Channel Model . . . . . . . . . . . . . . . . . . . . . 46
3.3 All Subcarrier Relaying . . . . . . . . . . . . . . . . . . . . . . . . 50
3.3.1 Relay Selection . . . . . . . . . . . . . . . . . . . . . . . . 51
3.3.2 Power Allocation . . . . . . . . . . . . . . . . . . . . . . . 51
3.4 Selective Subcarrier Relaying . . . . . . . . . . . . . . . . . . . . 55
3.4.1 Subcarrier and Relay Selection . . . . . . . . . . . . . . . . 56
3.4.2 Power Allocation . . . . . . . . . . . . . . . . . . . . . . . 58
3.4.3 Resource Allocation Algorithm . . . . . . . . . . . . . . . 61
CONTENTS viii
3.5 Numerical Results and Discussion . . . . . . . . . . . . . . . . . . 63
3.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
4 Power Allocation in OFDM Relay Networks with Outdated CSI 69
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
4.2 System and Channel Model . . . . . . . . . . . . . . . . . . . . . 71
4.3 Maximizing Instantaneous Rate . . . . . . . . . . . . . . . . . . . 74
4.4 Maximizing Expected Rate . . . . . . . . . . . . . . . . . . . . . . 77
4.4.1 Numerical Results and Discussion . . . . . . . . . . . . . . 80
4.5 Maximizing Outage Rate . . . . . . . . . . . . . . . . . . . . . . . 82
4.5.1 Numerical Results and Discussion . . . . . . . . . . . . . . 86
4.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
5 Resource Allocation in OFDM Cognitive Radio Relay Networks 91
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
5.2 System and Channel Model . . . . . . . . . . . . . . . . . . . . . 94
5.3 Problem Formulation . . . . . . . . . . . . . . . . . . . . . . . . . 97
5.4 Proposed Resource Allocation Methods . . . . . . . . . . . . . . . 100
5.4.1 Resource Allocation Method A . . . . . . . . . . . . . . . 100
5.4.1.1 Simpli(cid:28)ed Relay Selection . . . . . . . . . . . . . 101
5.4.1.2 Optimal Power Allocation . . . . . . . . . . . . . 102
5.4.2 Resource Allocation Method B . . . . . . . . . . . . . . . 105
5.5 Joint Optimal Resource Allocation . . . . . . . . . . . . . . . . . 106
5.6 Numerical Results and Discussion . . . . . . . . . . . . . . . . . . 106
5.7 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
6 Power Allocation in OFDM CR Relay Networks with Knowledge
of Statistical CSI 115
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
6.2 System and Channel Model . . . . . . . . . . . . . . . . . . . . . 117
CONTENTS ix
6.3 Power Allocation for DF Relay Assisted CR Networks . . . . . . . 123
6.3.1 Optimal Power Allocation Method . . . . . . . . . . . . . 124
6.3.2 Suboptimal Power Allocation Method . . . . . . . . . . . . 125
6.4 Power Allocation for AF Relay Assisted CR Networks . . . . . . . 129
6.4.1 Optimal Power Allocation Method . . . . . . . . . . . . . 130
6.4.2 Suboptimal Power Allocation Method . . . . . . . . . . . . 132
6.5 Uniform Power Allocation Method . . . . . . . . . . . . . . . . . 134
6.6 Numerical Results and Discussion . . . . . . . . . . . . . . . . . . 135
6.7 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
7 Power Allocation in OFDM Cognitive Radio Networks Operat-
ing in TV White Space 147
7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
7.2 Related Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
7.3 System and Channel Model . . . . . . . . . . . . . . . . . . . . . 152
7.4 Power Allocation for Interference Minimization . . . . . . . . . . . 155
7.4.1 Simpli(cid:28)ed Power Allocation Algorithm . . . . . . . . . . . 158
7.5 Comparison with Other Power Allocation Methods . . . . . . . . 160
7.5.1 Water Filling Power Allocation . . . . . . . . . . . . . . . 160
7.5.2 Capacity Threshold Based Power Allocation . . . . . . . . 161
7.6 Numerical Results and Discussion . . . . . . . . . . . . . . . . . . 161
7.7 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
8 Conclusion 167
8.1 Summary and Conclusion . . . . . . . . . . . . . . . . . . . . . . 168
8.2 Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
References 173
Appendices 188