MINISTRY OF EDUCATION & TRAINING MINISTRY OF NATIONAL DEFENSE MILITARY TECHNICAL ACADEMY LE THI THANH HUYEN REPEATED INDEX MODULATION FOR OFDM SYSTEMS A Thesis for the Degree of Doctor of Philosophy HA NOI - 2020 MINISTRY OF EDUCATION & TRAINING MINISTRY OF NATIONAL DEFENSE MILITARY TECHNICAL ACADEMY LE THI THANH HUYEN REPEATED INDEX MODULATION FOR OFDM SYSTEMS A Thesis for the Degree of Doctor of Philosophy Specialization: Electronic Engineering Specialization code: 52 02 03 SUPERVISOR Prof TRAN XUAN NAM HA NOI - 2020 ASSURANCE I hereby declare that this thesis was carried out by myself under the guidance of my supervisor The presented results and data in the thesis are reliable and have not been published anywhere in the form of books, monographs or articles The references in the thesis are cited in accordance with the university’s regulations Hanoi, May 17th, 2019 Author Le Thi Thanh Huyen ACKNOWLEDGEMENTS It is a pleasure to take this opportunity to send my very great appreciation to those who made this thesis possible with their supports First, I would like to express my deep gratitude to my supervisor, Prof Tran Xuan Nam, for his guidance, encouragement and meaningful critiques during my researching process This thesis would not have been completed without him My special thanks are sent to my lecturers in Faculty of Radio - Electronics, especially my lecturers and colleagues in Department of Communications who share a variety of difficulties for me to have more time to concentrate on researching I also would like to sincerely thank my research group for sharing their knowledge and valuable assistance Finally, my gratitude is for my family members who support my studies with strong encouragement and sympathy Especially, my deepest love is for my mother and two little sons who always are my endless inspiration and motivation for me to overcome all obstacles Author Le Thi Thanh Huyen TABLE OF CONTENTS Contents List of abbreviations iv List of figures vii List of tables x List of symbols xi INTRODUCTION Chapter RESEARCH BACKGROUND 1.1 Basic principle of IM-OFDM 1.1.1 IM-OFDM model 1.1.2 Sub-carrier mapping 12 1.1.3 IM-OFDM signal detection 14 1.1.4 Advantages and disadvantages of IM-OFDM 16 1.2 Related works 17 1.3 Summary 23 Chapter REPEATED INDEX MODULATION FOR OFDM WITH DIVERSITY RECEPTION 24 2.1 RIM-OFDM with diversity reception model 24 2.2 Performance analysis of RIM-OFDM-MRC/SC under perfect CSI 28 2.2.1 Performance analysis for RIM-OFDM-MRC i 29 2.2.2 Performance analysis for RIM-OFDM-SC 34 2.3 Performance analysis of RIM-OFDM-MRC/SC under imperfect CSI 35 2.3.1 Performance analysis for RIM-OFDM-MRC 35 2.3.2 Performance analysis for RIM-OFDM-SC 40 2.4 Performance evaluation and discussion 41 2.4.1 Performance evaluation under perfect CSI 41 2.4.2 SEP performance evaluation under imperfect CSI condition 48 2.4.3 Comparison of the computational complexity 49 2.5 Summary 50 Chapter REPEATED INDEX MODULATION FOR OFDM WITH COORDINATE INTERLEAVING 51 3.1 RIM-OFDM-CI system model 51 3.2 Performance analysis 56 3.2.1 Symbol error probability derivation 56 3.2.2 Asymptotic analysis 59 3.2.3 Optimization of rotation angle 60 3.3 Low-complexity detectors for RIM-OFDM-CI 62 3.3.1 Low-complexity ML detector 62 3.3.2 LLR detector 65 3.3.3 GD detector 66 3.4 Complexity Analysis 67 3.5 Performance evaluations and discussion 69 ii 3.6 Summary 75 CONCLUSIONS AND FUTURE WORK 76 PUBLICATIONS 79 BIBLIOGRAPHY 81 iii LIST OF ABBREVIATIONS Abbreviation Definition AWGN Additive White Gaussian Noise BEP Bit Error Probability BER Bit Error Rate CI Coordinate Interleaving CS Compressed Sensing CSI Channel State Information D2D Device to Device ESIM-OFDM Enhanced Sub-carrier Index Modulation for Orthogonal Frequency Division Multiplexing FBMC Filter Bank Multi-Carrier FFT Fast Fourier Transform GD Greedy Detection ICI Inter-Channel Interference IEP Index Error Probability IFFT Inverse Fast Fourier Transform IM Index Modulation IM-OFDM Index Modulation for OFDM iv IM-OFDM-CI Index Modulation for OFDM with Coordinate Interleaving IoT Internet of Things ISI Inter-Symbol Interference ITU International Telecommunications Union LowML Low-complexity Maximum Likelihood LLR Log Likelihood Ratio LUT Look-up Table M2M Machine to Machine Mbps Megabit per second MGF Moment Generating Function MIMO Multiple Input Multiple Output ML Maximum Likelihood MM-IM-OFDM Multi-Mode IM-OFDM MRC Maximal Ratio Combining NOMA Non-Orthogonal Multiple Access OFDM Orthogonal Frequency Division Multiplexing OFDM-GIM OFDM with Generalized IM OFDM-I/Q-IM OFDM with In-phase and Quadrature Index Modulation OFDM-SS OFDM Spread Spectrum PAPR Peak-to-Average Power Ratio PEP Pairwise Error Probability PIEP Pairwise Index Error Probability v PSK Phase Shift Keying QAM Quadrature Amplitude Modulation RIM-OFDM Repeated Index Modulation for OFDM RIM-OFDM-MRC Repeated Index Modulation for OFDM with Maximal Ratio Combining RIM-OFDM-SC Repeated Index Modulation for OFDM with Selection Combining RIM-OFDM-CI Repeated Index Modulation for OFDM with Coordinate Interleaving SC Selection Combining SEP Symbol Error Probability SIMO Single Input Multiple Output S-IM-OFDM Spread IM-OFDM SNR Signal to Noise Ratio SM Spatial Modulation SS Spread Spectrum UWA Underwater Acoustic V2V Vehicle to Vehicle V2X Vehicle to Everything xG x-th Generation vi CONCLUSIONS AND SUGGESTIONS FOR FUTURE WORKS This section summarizes the contributions of the thesis and presents some open problems for future studies A Conclusions This thesis has conducted a detailed investigation on the IM-OFDM system Inspired by the the recent contributions of IM-OFDM, the thesis has proposed two enhanced RIM-OFDM systems to achieve the improved error performance over the conventional IM-OFDM system In particular, the RIM-OFDM system with diversity reception was proposed to simultaneously exploit the frequency and spatial diversity and to achieve the better SEP performance than the conventional IMOFDM with diversity reception The closed-form expressions for the IEP and SEP of the proposed system under both perfect and imperfect channel state information conditions are derived Based on the performance analysis, the impacts of the system parameters on the transmission reliability are evaluated Simulation results are also provided to validate the theoretical analysis The RIM-OFDM with coordinate interleaving was proposed to attain the improved error performance in the index domain and an flexible trade-off between the transmission reliability and the spectral efficiency 76 Additionally, the closed-form expressions for IEP, SEP and BEP were derived for the proposed RIM-OFDM-CI systems These expressions can be used as an efficient framework to investigate the system performance and provide an insight into the impacts of the system parameters on the performance Specially, based on the performance analysis, a simple method without using computer search to optimize the rotation angle of the M -ary modulation constellation is proposed Besides, the lowcomplexity detectors were also introduced to relax the computational complexity requirement of the IM-OFDM detectors The introduced detectors can significantly reduce the detection complexity while still achieve nearly same performance of the optimal ML detector In comparison with the previous IM-OFDM systems, the proposed systems not only attain better transmission reliability but also more flexible in terms of balancing the required performance with the spectral efficiency With their advantages in terms of low complexity and superior in the error performance, the proposed RIM-OFDM systems can be possible candidates to replace the OFDM systems in the future wireless communication networks B Future Works Referring to above conclusions, there are still several possible open problems which require further investigations in order to have a full understanding about applicability of the proposed systems into the future networks as follows: • The proposed RIM-OFDM-MRC/SC system uses ML detector which 77 has high complexity The proposal of detectors to reduce the complexity of ML could be an interesting topic for future research • The proposal in Chapter is considered for SIMO configuration In order to further improve the diversity gain and transmission reliability, extending RIM-OFDM to the MIMO and cooperative communication systems is a challenging topic and very attractive for future works • The performance of the RIM-OFDM-CI system in Chapter is investigated under the perfect CSI condition Evaluating the impacts of channel estimation errors on the system performance is a significantly meaningful topic for future research • The proposals in Chapter and Chapter of the thesis consider the uncoded systems, it is more interesting when evaluating the SEP and BER performance of the system with channel coding • The performance in terms of SEP and BER is analyzed for the two proposed systems Further analysis using other evaluated parameters would probably give additional insights into the performance of the proposed systems 78 PUBLICATIONS [J1] L T T Huyen, and T X Nam, “Performance Analysis of Repeated Index Modulation for OFDM with MRC Diversity over Nakagami-m Fading Channel,” Journal of Science and Technology, No.196, pp 90–102, Feb., 2019 [J2] T T H Le, X N Tran, “Performance Analysis of Repeated Index Modulation for OFDM with MRC and SC diversity Under Imperfect CSI,” AEU - International Journal of Electronics and Communications, (ISI-SCI, Q2, IF=2.853), Vol 107, pp 199-208, Jul 2019, https://doi.org/10.1016/j.aeue.2019.05.022, Available online 23 May, 2019 [J3] L T T Huyen, and T X Nam, “Performance Analysis of Repeated Index Modulation with Coordinate Interleaving over Nakagamim Fading Channel,” Research and Development on Information and Communication Technology (RD-ICT) of Journal of Information and Communication Technology, Vol 2019, No 1, pp 23-30, Jun 2019 [J4] T T H Le, V D Ngo, M T Le, X N Tran, “Repeated Index Modulation-OFDM with Coordinate Interleaving: Performance Optimization and Low-Complexity Detectors,” IEEE Systems Journal, 79 (ISI - SCI, Q1, IF=4.463), vol , no , pp , 20xx (Under review) [C1] T T H Le, X N Tran, “Repeated index modulation for OFDM with space and frequency diversity,” Advanced Technologies for Communications (ATC), 2017 International Conference on IEEE, pp 97–102, Oct., 2017 (Scopus) [C2] T T H Le, V D Ngo, M T Le, X N Tran, “Repeated Index Modulation with Coordinate Interleaved OFDM,” 2018 5th NAFOSTED Conference on Information and Computer Science (NICS), pp 115-119, Nov., 2018 (Scopus) 80 BIBLIOGRAPHY [1] Z E Ankarali, B Pekăoz, and H Arslan, “Flexible Radio Access Beyond 5G: A Future Projection on Waveform, Numerology, and Frame Design Principles,” IEEE Access, vol 5, pp 18 295–18 309, Mar 2017 [2] J G Andrews, S Buzzi, W Choi, S V Hanly, A Lozano, A C Soong, and J C Zhang, “What will 5G be?” IEEE J Sel 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MM-IM -OFDM Multi-Mode IM -OFDM MRC Maximal Ratio Combining NOMA Non-Orthogonal Multiple Access OFDM Orthogonal Frequency Division Multiplexing OFDM- GIM OFDM with Generalized IM OFDM- I/Q-IM OFDM. .. Amplitude Modulation RIM -OFDM Repeated Index Modulation for OFDM RIM -OFDM- MRC Repeated Index Modulation for OFDM with Maximal Ratio Combining RIM -OFDM- SC Repeated Index Modulation for OFDM with Selection... to IM -OFDM with coordinate interleaving – Based on the idea of IM -OFDM with coordinate interleaving (IM -OFDM- CI) [7], an enhanced scheme of IM -OFDM, referred to as repeated IM -OFDM- CI (RIM -OFDM- CI)