New Jersey Institute of Technology Digital Commons @ NJIT Dissertations Electronic Theses and Dissertations Summer 8-31-2003 Capacity, coding and interference cancellation in multiuser multicarrier wireless communications systems Christian Ibars Casas New Jersey Institute of Technology Follow this and additional works at: https://digitalcommons.njit.edu/dissertations Part of the Electrical and Electronics Commons Recommended Citation Ibars Casas, Christian, "Capacity, coding and interference cancellation in multiuser multicarrier wireless communications systems" (2003). Dissertations. 590. https://digitalcommons.njit.edu/dissertations/590 This Dissertation is brought to you for free and open access by the Electronic Theses and Dissertations at Digital Commons @ NJIT. It has been accepted for inclusion in Dissertations by an authorized administrator of Digital Commons @ NJIT. For more information, please contact [email protected]. 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Please Note: The author retains the copyright while the New Jersey Institute of Technology reserves the right to distribute this thesis or dissertation Printing note: If you do not wish to print this page, then select “Pages from: first page # to: last page #” on the print dialog screen The Van Houten library has removed some of the personal information and all signatures from the approval page and biographical sketches of theses and dissertations in order to protect the identity of NJIT graduates and faculty. ASAC CAACIY COIG A IEEECE CACEAIO I MUIUSE MUICAIE WIEESS COMMUICAIOS SYSEMS b Chrtn Ibr C Multicarrier modulation and multiuser systems have generated a great deal of research during the last decade. Orthogonal Frequency Division Multiplexing (OFDM) is a multicarrier modulation generated with the inverse Discrete Fourier Transform, which has been adopted for standards in wireless and wire-line communications. Multiuser wireless systems using multicarrier modulation suffer from the effects of dispersive fading channels, which create multi-access, inter-symbol, and inter-carrier interference (MAI, ISI, ICI). Nevertheless, channel dispersion also provides diversity, which can be exploited and has the potential to increase robustness against fading. Multiuser multi- carrier systems can be implemented using Orthogonal Frequency Division Multiple Access (OFDMA), a flexible orthogonal multiplexing scheme that can implement time and frequency division multiplexing, and using multicarrier code division multiple access (MC-CDMA). Coding, interference cancellation, and resource sharing schemes to improve the performance of multiuser multicarrier systems on wireless channels were addressed in this dissertation. Performance of multiple access schemes applied to a downlink multiuser wireless system was studied from an information theory perspective and from a more practical perspective. For time, frequency, and code division, implemented using OFDMA and MC-CDMA, the system outage capacity region was calculated for a correlated fading channel. It was found that receiver complexity determines which scheme offers larger capacity regions, and that OFDMA results in a better compromise between complexity and performance than MC-CDMA. From the more practical perspective of bit error rate, the effects of channel coding and interleaving were investigated. Results in terms of coding bounds as well as simulation were obtained, showing that OFDMA- based orthogonal multiple access schemes are more sensitive to the effectiveness of the code to provide diversity than non-orthogonal, MC-CDMA-based schemes. While cellular multiuser schemes suffer mainly from MAI, OFDM-based broad- casting systems suffer from ICI, in particular when operating as a single frequency network (SFN). It was found that for SFN the performance of a conventional OFDM receiver rapidly degrades when transmitters have frequency synchronization errors. Several methods based on linear and decision-feedback ICI cancellation were proposed and evaluated, showing improved robustness against ICI. System function characterization of time-variant dispersive channels is important for understanding their effects on single carrier and multicarrier modulation. Using time-frequency duality it was shown that MC-CDMA and DS-CDMA are strictly dual on dispersive channels. This property was used to derive optimal matched filter structures, and to determine a criterion for the selection of spreading sequences for both DS and MC CDMA. The analysis of multiple antenna systems provided a unified framework for the study of DS-CDMA and MC-CDMA on time and frequency dispersive channels, which can also be used to compare their performance. CAACIY COIG A IEEECE CACEAIO I MUIUSE MUICAIE WIEESS COMMUICAIOS SYSEMS b Chrtn Ibr C A rttn Sbttd t th lt f r Inttt f hnl n rtl lfllnt f th rnt fr th r f tr f hlph n Eltrl Ennrn prtnt f Eltrl nd Cptr Ennrn At 3 Copyright © 2003 by Christian Ibars Casas ALL RIGHTS RESERVED AOA AGE CAACIY COIG A IEEECE CACEAIO I MUIUSE MUICAIE WIEESS COMMUICAIOS SYSEMS Chrtn Ibr C Yeeskea-ess isseaio Aiso ae isiguise oesso eame o Eecica a Comue Egieeig I Aeae aimoic Commiee Meme ae oesso eame o Eecica a Comue Egieeig I ogya Ge Commiee Meme ae Associae oesso eame o Eecica a Comue Egieeig I Ai Ai Commiee Meme ae Assisa oesso eame o Eecica a Comue Egieeig I oy Yaes Commiee Meme ae oesso a Associae ieco WIA uges Uiesiy IOGAICA SKEC Athr Christian Ibars Casas r Doctor of Philosophy t August 2003 Undrrdt nd Grdt Edtn • Doctor of Philosophy in Electrical Engineering, New Jersey Institute of Technology, 2003 • Master of Science in Electrical Engineering, Universitat Politècnica de Catalonia, Barcelona, Spain, 1999 • Master of Science in Electronics Engineering, Politècnica di Torino, Torino, Italy, 1999 Mjr Electrical Engineering rnttn nd bltn C. Ibars and Y. Bar-Ness, "Inter-Carrier Interference Cancellation for OFDM Systems with Macrodiversity and Multiple Frequency Offsets," to appear in Wieess esoa Commuicaios a ieaioa oua Kluwer Academic Publishers, 2003. C. Ibars and Y. Bar-Ness, "Analysis of Time-Frequency Duality of MC and DS CDMA for Multi-Antenna Systems on Highly Time-Varying Wideband Channels," submitted, IEEE asacios o Wieess Commuicaios August 2003. C. Ibars and Y. Bar-Ness," Outage capacities of a multi-carrier WLAN downlink under different resource sharing techniques," oc IEEE Ieaioa Symosium o Sea Secum eciques a Aicaios (ISSSA vol. 1, pp. 144-149, Prague, Czech Republic, September 2002. C. Ibars and Y. Bar-Ness, "OFDM detection in a macrodiversity system with multiple frequency offsets," oc 3G Wieess San Francisco, CA, May 2002. C. Ibars and Y. Bar-Ness, "The principle of time-frequency duality of DS and MC CDMA," oc 3 Aua Coeece o Iomaio Scieces a Sysems (CISS Princeton, New Jersey, March 2002. v C Ias a Y a-ess "ae-Aaie Coe Muiuse OM o owik Wieess Sysems" Mui-Caie Sea-Secum & eae oics K ae a S Kaise es 199-7 Kuwe C Ias a Y a-ess "Comaig e eomace o Coe Muiuse OM a Mui-Caie CMA" oc o e 1 IEEE Goa Commuicaios Coeece (Goecom1 o 1-5 Sa Aoio USA oeme 1 As meus aes (o my aes i ACKOWEGME This work could not have been accomplished without the contribution of friend- ship, support and guidance of many people. First and foremost, I would like to express my sincere gratitude to my advisor, Dr. Yeheskel Bar-Ness for guiding me through the dissertation. He has taught me how to conduct strong research, and his encouragement and support during my studies have been invaluable. I would also like to express my appreciation to the distinguished members of the dissertation committee: Dr. Alexander Haimovich, Dr. Hongya Ge, Dr. Ali Abdi and Dr. Roy Yates. Their insightful comments have improved the quality of this dissertation. Funding for my research was provided by the Ross Fellowship Memorial Fund. I am indebted to Dr. Ronald Kane and Dr. Sotirios Ziavras for ensuring the contin- uation of financial support. Many thanks are due to Dr. John Cioffi, for his valuable discussions and advice, and for his logistic support during my stay at Stanford University, which I greatly enjoyed. I extend my gratitude to the members and visitors of his research group for providing a great research environment. Everyone at the Center for Communications and Signal Processing Research deserves thanks for assistance during many stages of this work, and for generating a creative and enjoyable atmosphere to work in. Thanks to Mizhou Tan and Jianming Zhu for your help with my research. My colleagues Daniel Perez Palomar and Albert Guillen Fabregas also deserve special mention for their help in parts of this disser- tation. Finally, I sincerely thank Montse and my family for continued support and encouragement which have made possible this accomplishment and all of my friends at the CCSPR