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BEAMFORMING FOR MULTIUSER MIMO · PDF fileBEAMFORMING FOR MULTIUSER MIMO SYSTEMS by Milad Amir Toutounchian M.Sc., Iran University of Science and Technology, 2005 B.Sc.,Sharif University

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  • 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

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