Ramesh Chembil Palat
Dissertation submitted to the Faculty of
Virginia Polytechnic Institute and State University
in partial fulfillment of the requirements of the degree of
DOCTOR OF PHILOSOPHY
Jeffrey H. Reed (Co-chair)
A. Annamalai (Co-Chair)
William H. Tranter
Steven W. Ellingson
Calvin J. Ribbens
December 8, 2006
Keywords: Cooperative Communication, Relaying, MIMO, Wireless Communications Copyright 2006, Ramesh Chembil Palat
Performance Analysis of Cooperative Communication
for Wireless Networks
Ramesh Chembil Palat
The demand for access to information when and where you need has motivated the transition of wireless communications from a fixed infrastructure based cellular communications technology to a more pervasive adhoc wireless networking technology. Challenges still remain in wireless adhoc networks in terms of meeting higher capacity demands, improved reliability and longer connectivity before it becomes a viable widespread commercial technology. Present day wireless mesh networking uses node-tonode serial multi-hop communication to convey information from source to destination in the network. The performance of such a network depends on finding the best possible route between the source and destination nodes. However the end-to-end performance can only be as good as the weakest link within a chosen route. Unlike wired networks, the quality of point-to-point links in a wireless mesh network is subject to random fluctuations. This adversely affects the performance resulting in poor throughput and poor energy efficiency.
In recent years, a new paradigm for communication called cooperative communications has been proposed for which initial information theoretic studies have shown the potential for improvements in capacity over traditional multi-hop wireless networks. Cooperative communication involves exploiting the broadcast nature of the wireless medium to form virtual antenna arrays out of independent single-antenna network nodes for transmission. In this research we explore the fundamental performance limits of iii
cooperative communication under more practical operating scenarios. Specifically we provide a framework for computing the outage and ergodic capacities of non identical distributed MIMO links, study the effect of time synchronization error on system performance, analyze the end-to-end average bit error rate (ABER) performance under imperfect relaying, and study range extension and energy efficiency offered by the system when compared to a traditional system.
My sincere appreciation goes to Dr. Jeffrey H. Reed for his valuable guidance, technical inputs and encouragement throughout my course of study at Virginia Tech. He has allowed me a free hand in exploring many ideas and I have gained immensely from them. I would like to express my gratitude to Dr. Annamalai for being a great mentor and for numerous technical discussions and suggestions that have found their way into this dissertation. I would also like to thank Dr. William H. Tranter, Dr. Steven S. Ellingson, and Dr. Calvin J. Ribbens for serving on my committee, for their guidance and criticism offered.
I would like to acknowledge the support from Wireless @ Virginia Tech industrial affiliates program and Office of Naval Research for sponsoring this research. I greatly appreciate the help of the MPRG staff including Shelby Smith, Hilda Reynolds, Jenny Frank and Cindy Graham for taking excellent care of many of our administrative needs. This journey towards a PhD would not have been an enjoyable one without the friendship and assistance from my fellow MPRG students including Ran Gozali, Raqibul Mostafa, James Hicks, William Newhall, Max Roberts, Srikathyayani Srikanteswara, Carl Dietrich, Shakheela Marikar, Maruf Mohammad, Jody Neel, Chris Anderson, Yash Vasavada, Sesh...