BEAMFORMING FOR MULTIUSER MIMO SYSTEMS
by
Milad Amir Toutounchian
M.Sc., Iran University of Science and Technology, 2005
B.Sc.,Sharif University of Technology, 2002
a Thesis submitted in partial fulfillment
of the requirements for the degree of
Doctor of Philosophy
in the
School of Engineering Science
Faculty of Applied Sciences
c⃝ Milad Amir Toutounchian 2014
SIMON FRASER UNIVERSITY
Fall 2014
All rights reserved.
However, in accordance with the Copyright Act of Canada, this work may be
reproduced without authorization under the conditions for “Fair Dealing.”
Therefore, limited reproduction of this work for the purposes of private study,
research, criticism, review and news reporting is likely to be in accordance
with the law, particularly if cited appropriately.
APPROVAL
Name: Milad Amir Toutounchian
Degree: Doctor of Philosophy
Title of Thesis: BEAMFORMING FOR MULTIUSER MIMO SYSTEMS
Examining Committee: Dr. Ivan Bajic
Chair
Dr. Rodney Vaughan, Professor, Simon Fraser University
Senior Supervisor
Dr. Paul Ho, Professor, Simon Fraser University
Supervisor
Dr. Jie Liang, Associate Professor, Simon Fraser Univer-
sity
Supervisor
Dr. Daniel C. Lee, Professor, Simon Fraser University
Internal Examiner
Dr. Lutz Lampe, Professor, University of British Columbia
External Examiner
Date Defended/Approved: September 5th, 2014
ii
Partial Copyright Licence
iii
Abstract
Wireless communications systems use a multiple user scheme such as time- or frequency-division,
but these do not allow truly simultaneous use of the spectrum. By deploying multiple antennas and
beamforming, it is possible, in principle, for users to share the spectrum simultaneously, and this
scenario is called the multiuser MIMO interference channel. This thesis presents new beamfoming
design methods for this channel, derived from the convergence criteria for multi-objective opti-
mization. Beamforming is proven to be possible for any combination of communications objective
functions such as mean-square error, signal-to-interference plus noise ratio, and leakage interference.
Relationships are found between the number of users and number of antennas, for different objec-
tive functions. The existence of a Nash equilibrium is guaranteed and the important networking
properties of quality of service and fairness among users are accounted for. A new optimization
algorithm, which is an extension of alternating optimization, is formulated for the design process.
Its advantage over existing approaches is its significantly lower computational complexity. Several
optimized, multi-user OFDM systems are formulated and demonstrated by simulation using statis-
tical channel models in a multipath environment. The feedback overhead required for deploying the
beamforming is quantified, showing the trade-off among complexity, minimum number of antennas
required, error performance, capacity, feedback rate, and the ability to extract multi-path diversity
for multiple users. When one of the users has priority access to the spectrum, the channel takes on
a form of cognitive radio. This scenario is formulated as an optimization which requires solution via
an evolutionary algorithm, and convergence is shown to be faster when more antennas are deployed.
Finally, an architecture is presented that enables a secondary (i.e., low priority) user, whose termi-
nals cannot directly ”see” each other, to communicate in the presence of multiple primary users.
The cost is the need for all the primary users to be modified to collaborate with the secondary user,
and for several MIMO relays to be installed. The secondary capacity is maximized under constraints
of transmission power and interference to the primary receivers, and relay selection. This concept
showcases several communications techniques including eigen-beamforming, channel selection and
capacity optimization.
iv
To my beloved parents, Sousan and Iraj
for their unconditional affection, support, encourage and guidance
and to my sister and brother, Pouneh and Amirhossein
for their kindness and friendship
and to my wife, Ouldooz
for her vibes and support
v
“There is no greater wealth than wisdom, no greater poverty than ignorance, no greater heritage
than culture, and no greater friend and helpmate than consultation.”
— Nahjul Balagha, Imam Ali (AS), 610-673 A.D.
vi
Acknowledgments
Thanks to God whose blessings and merciful have made me who I am today. The PhD is a very
long journey with many ups and downs, and without collaboration with supportive people it is never
being accomplished. I do remember when I wanted to start the program my senior supervisor, Pro-
fessor Rodney G. Vaughan, told me that it is a big commitment. Now, I have realized it is a very
true statement.
It is not easy to thank my senior supervisor at the School of Engineering Science, SFU, Dr.
Rodney G. Vaughan just by some words. But what can I say, without any doubt, I could complete
the program with a high level of my personal satisfaction only because of Dr. Vaughan. He has a
unique academic and personal character. Dr. Vaughan is a great mentor that seeks his students’
interests first and flourish them patiently. He is a very good friend for his students as well. Dr.
Vaughan taught me, by his manner, that the knowledge and personality should come together. I
have been extremely lucky to have a senior supervisor who cared so much about my work and my
life. With his persistent encouragement, I could explore, study and accomplish research in the last
couple of years. Finally, I want to acknowledge Dr. Vaughan deeply for his great support during my
PhD career technically and financially.
I want to express my gratitude to Professor Daniel C. Lee, my internal examiner, for his smart
questions and for his clever comments. Dr. Lee is a great faculty member with strong mathematical
background. He also teaches communication’s topics with solid proofs. The main contribution of
my thesis, which is optimization, is aligned with Dr. Lee’s interests and he helped me a lot in this
regard.
I would like to acknowledge Professor Paul Ho, my supervisor. His constructive comments really
improved the flow of the thesis in its final version. I managed to get the highest grade for the course
Advanced Digital Communications offered by him just because he was always encouraging the mo-
tivated students. He taught me how to think analytically.
I would like to thank Professor Jie Liang, my supervisor. I have always wondered how he can get
the gist of any presentation or article so quickly and manage to emphesize/critisize the most funda-
mental aspect of the work. During my PhD program he was the graduate chair of the department.
All of the graduate students experienced one of the best administered and highly disciplined period
vii
with him.
I wish to express my appreciation to my external examiner from UBC, Professor Lutz Lampe.
I have had a course with him in September 2010. I have found him a very organized faculty with
diverse and deep knowledge in the wireless/wired communication systems. I really appreciate his
time for revising my thesis and providing insightful feedbacks to me.
It is my honor to thank Professor Ivan V. Bajic who accepted to hold the role of the session chair
for my thesis defense. For two consecutive semesters, he gave me the chance to experience the role
of course developer for engineering analysis.
Finally, I am so grateful to Professor Kamal Gupta who accelerate my admission process and
Professor Sami Muhaidat who was my supervisor and supported me for the first year of my program.
Last, but by no means least, I want to warmly thanks my great friends in Sierra Wireless Com-
munications Laboratory, Mehdi Seyfi for his great help and consultation whenever I encountered to
a hard problem, Saeed Ashrafinia for his vibes, Maral Dehghani for her kindness and her editorial
skills, Ali Zarei, Alireza Banani, Sara Bavarian, Mahsa Najibi, Moein Shayegania, Maryam Razmhos-
seini, Piraj Fozoonmayeh, Omar Altrad, Ying Chen, Muhammad Naeem and Abhijit Bhattacharya.
I experienced a very pleasant environment in this lab. As a visiting graduate researcher at UCLA
in fall 2012, I want to deeply appreciate, Professor Ali H. Sayed for his hospitality and informative
meetings, Zaid Towfic, Xiaochuan Zhao, Jianshu Chen, Harishan and Shang Kee Ting.
Besides the academic supporters and educational mentors, I owe my parents who have always
been role models for me. Both of them are highly educated people who never tire of being bene-
ficial to the society. They enlighten my professional path undoubtedly. They strongly encouraged
me to expand my skills and experience academic and social life in western countries. I declare my
immense gratitude to my lovely and caring wife, brother and sister as wel
