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ASAC A EUCIO I OM COMMUICAIOS WI GEEAIE ISCEE OUIE ASOM b Srt Sn h n dvnt f Gnrlzd rt rr rnfr (G t blt t dn d ltn f ntnt dl rthnl d t bd n th drd prfrn tr n th nnrn p f ntrt On f th n drb f Orthnl rn vn Mltplxn (OM t th hh t Avr r t (A vl hh drtl rltd t pr nptn f th t rt rr rnfr ( prd OM thnl l nn Snl Crrr rn vn Mltpl A (SCMA hh h lr A vl d fr pln hnnl In th th th A f prd OM frthr drd b n G npt h prfrn prvnt f G bd A rdtn fr vr SCMA ntn nr r vltd b ltn rfrn ltn rlt hd tht A ffn f SCMA t fr nr h Shft Kn (SK Qdrtr h Shft Kn (QSK nd 1 Qdrtr Apltd Mdltn (1-QAM dtl dltn thn r nrd A EUCIO I OM COMMUICAIOS WI GEEAIE ISCEE OUIE ASOM b Srt Sn A h Sbttd t th lt f r Inttt f hnl n rtl lfllnt f th rnt fr th r f Mtr f Sn n Eltrl Ennrn prtnt f Eltrl nd Cptr Ennrn M 1 APPROVAL PAGE PAPR REDUCTION IN OFDM COMMUNICATIONS WITH GDFT Sertac Sayin Dr. Ali Akansu, Thesis Advisor Date Professor of Electrical and Computer Engineering, NJIT Dr. Alex Haimovich, Committee Member Date Professor of Electrical and Computer Engineering, NJIT Dr. Osvaldo Simeone, Committee Member Date Assistant Professor of Electrical and Computer Engineering, NJIT BIOGRAPHICAL SKETCH Author: Sertac Sayin Degree: Master of Science Date: May 2010 Undergraduate and Graduate Education: • Master of Science in Electrical Engineering, New Jersey Institute of Technology, Newark, NJ, 2010 • Bachelor of Science in Electrical Engineering, Middle East Technical University, Ankara, Turkey, 2003 Major: Electrical Engineering Svl nn Sbt S vl bb Sn Sn ye vl bl En Sn blvd thr Sbt Sn blvd fthr Sn S nd blvd tr En Sn ACKOWEGME First of all, I would like to express my sincere gratitude to my advisor, Professor Ali, Akansu, for all his support, encouragement and his guidance throughout my Master's study. He prepared me for the professional life. I am very grateful to Professor Alexander Haimovich and Assistant Professor Osvaldo Simeon of the ECE Department of NJIT for aggreing to participate on my thesis committee. I would like to thank to the Scientific and Technological Research Council of Turkey (TUBITAK) for their financial support for my master's study. I am proud they chose me out of many candidates. The last and the most, I would like to thank my family for their support. Even though they are 5000 miles away, they were always there for me. Especially, I want to thank them for the long, supportive and encouraging phone calls. Without them I could not finish this thesis. v TABLE OF CONTENTS Chapter Page 1 INTRODUCTION 1 1.1 Objective 1 1.2 Background Information 1 2 LTE OVERVIEW AS OFDMA AND SCFDMA 3 2.1 OFDMA 3 2.2 OFDMA Architecture 5 2.3 OFDMA Frame Structure 6 2.4 SCFDMA 6 2.5 SCFDMA Architecture 7 2.6 SCFDMA Frame Structure 12 3 GENERALIZED DFT 14 3.1 Theory of DFT and GDFT 14 3.2 GDFT Design 16 4 PEAK TO AVERAGE POWER RATIO REDUCTION IN SCFDMA WITH GDFT 18 4.1 Theory 18 4.2 SCFDMA Analysis 19 4.3 Design and Performance of GDFT Based SCFDMA 21 5 CONCLUSION 34 APPENDIX MATLAB CODE USED FOR SIMULATIONS 36 REFERENCES 40 vii LIST OF FIGURES Figure Page 2.1 Conventional FDMA (the upper one) and Orthogonal (the lower one) FDMA 3 2.2 The carrier signals in frequency domain and in time domain 4 2.3 OFDMA system block diagram 6 2.4 Difference Between Channel Representations Between OFDMA and SCFDMA... 7 2.5 SCFDMA system block diagram for transmitter and receiver 8 2.6 SCFDMA Subcarrier Mappings; Distributed and Localized Modes 9 2.7 Comparison of PAPR for different subcarrier mapping types of SCFDMA with DFT size 16 and IDFT size 512 10 2.8 Comparison of CCDF of PAPR for IFDMA, DFDMA, LFDMA and OFDMA..... 11 2.9 Resource block for LTE system 13 4.1 SCFDMA block diagram 19 4.2 Position of elements of° (a) before multiplying (b) after multiplying with G matrix 24 4.3 Position of elements of 0 (a) before multiplying (b) after multiplying with G matrix 26 4.4 Proposed SCFDMA system block diagram 27 4.5 CCDF of PAPR for SCFDMA with DFT or GDFT size (N) =16 and IDFT size=32 with BPSK digital modulation 28 4.6 CCDF of PAPR for SCFDMA with DFT or GDFT size (N) =16 and IDFT size=64 with BPSK digital modulation 28 4.7 CCDF of PAPR for SCFDMA with DFT or GDFT size (N) =16 and IDFT size=512 with BPSK digital modulation 29 4.8 CCDF of PAPR for SCFDMA with DFT or GDFT size (N) =16 and IDFT size=2048 with BPSK digital modulation 29 viii LIST OF FIGURES (Continued) Figure Page 4.9 CCDF of PAPR for SCFDMA with DFT or GDFT size (N) =32 and IDFT size=64 with BPSK digital modulation 30 4.10 CCDF of PAPR for DFT or GDFT size (N) =16 and IDFT size=128, SCFDMA with BPSK digital modulation 30 4.11 CCDF of PAPR for DFT or GDFT size (N) =16 and IDFT-size=128, SCFDMA with BPSK digital modulation 31 4.12 CCDF of PAPR for DFT or GDFT size (N) =8 and IDFT size=16, SCFDMA with QPSK digital modulation 31 4.13 CCDF of PAPR for DFT or GDFT size (N) =64 and IDFT size=128, SCFDMA with QPSK digital modulation 32 4.14 CCDF of PAPR for DFT or GDFT size (N) =32 and IDFT size=64, SCFDMA with QAM digital modulation 32 ix CHAPTER 1 INTRODUCTION 1.1 Objective Objective of this thesis is to introduce a method to reduce peak to average power (PAPR) for Single Carrier Frequency Division Multiple Access (SCFDMA) with the Localized Frequency Division Multiple Access (LFDMA) subcarrier mapping for different digital modulation types like; Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK) and 16 Quadrature Amplitude Modulation (QAM). As background information, Long Term Evolution (LTE), a beyond third generation mobile broadband standard, successor to UMTS and CDMA2000 (which are 3G cellular technologies), is reviewed as two parts downlink, Orthogonal Frequency Division Multiple Access (OFDMA) and uplink SCFDMA. And Generalized Discrete Fourier Transform (GDFT) is introduced. Finally, the difference between conventional SCFDMA system and the proposed SCFDMA system is compared in terms of PAPR with different sizes of frequency band and different number of users. 1.2 Background Information Since the beginning of humanity, communication is one of the basic needs. At first, they started to communicate through fire, smoke... etc and then, the telegraph was invented. Wired phone invention followed telegraph and today, with the technological improvements, people can communicate wirelessly between each other through cell 1 2 phones in their pockets. Engineers are always looking for faster, reliable and safer solutions to problems. In the wireless communication field, the technology that is used as 3 rd Generation (3G) in the cell phones which is Code division Multiple Access (CDMA) based, has achieved its limits. So for further increase in throughput, the technology is changed to LTE. And LTE is based on OFDM in the downlink channel (link from station to mobile) and Discrete Fourier Transform (DFT) spread OFDM or in other words SCFDMA in the uplink channel (link from mobile to station). The reason to use two different standards for uplink and downlink is PAPR. PAPR is directly related to battery life of the mobile. So PAPR is not a big issue for downlink because station is stationary and does not require battery. However, mobiles are using battery therefore battery life is one of the biggest issues for them. SCFDMA has similar throughput performance and essentially the same overall complexity as OFDMA. A principal advantage of SC-FDMA is the peak-to-average power ratio (PAPR), which is lower than that of OFDMA. SCFDMA is currently a strong candidate for the uplink multiple access scheme in the Long Term Evolution of cellular systems under consideration by the Third Generation Partnership Project (3GPP).