Multi-rate MC-CDMA Multiuser Communication Systems with Adaptive Antenna Array

此論文著眼在多頻取樣多載波分碼多工多重接取(MC-CDMA)適應性通訊系統的後快速富立葉型式(post-FFT type)和前快速富立葉型式(pre-FFT Type)。在多路徑的衰減通道中，被傳輸的訊號會被下列舉出的特性所影響：符碼間的干擾(ICI)，多重接取的干擾(MAI)和多重使用者干擾(MUI)。為了解決這些問題，我們提出三種多頻取樣的數學方法-可變程序增益(VPG)，可變碼速率(VCR)和多重碼系統(multi-code)去調查多載波分碼多工通訊處理在多路徑的衰減通道中的效能表現。我們使用基本最小平方差(LMS)方法和在接收架構增加展頻碼係數。這項技術可以減少雜訊和干擾；換言之，它可以增加效能和可靠性。This paper proposes the adaptive multi-rate multi-carrier code-division multiple access (MC-CDMA) communication system with the post-FFT type and pre-FFT type. In multipath fading channel, the transmitted signal suffers from effects, which are characterized as follows: in inter-chip interference (ICI), multiple access interference (MAI) and multi-user interference (MUI). In order to solve these problems, we propose three multi-rate methodologies - variable processing gain (VPG), variable chip rate (VCR) and multi-code systems to investigate the performance of the MC-CDMA communications processing in multipath fading environments. We employ Least-Mean-Square (LMS)-based and include the spreading code coefficients in receiver structures. The technique can reduce noise and interference; moreover, it can enhance efficiency and reliability.CONTENTS LIST OF TABLES v LIST OF FIGURES vii 1 INTRODUCTION 1 2 CONCEPTS OF ADAPTIVE RECEIVER FOR MC-CDMA COMMUNICATION SYSTEMS 5 2.1 Orthogonal FrequencyDivisionMultiplexing (OFDM) . . . . . . . . . 5 2.2 CDMAbasics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.3 Smart antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.3.1 Types of Smart antennas . . . . . . . . . . . . . . . . . . . . . 8 2.3.2 Adaptive BeamformingAlgorithm . . . . . . . . . . . . . . . . 10 2.4 Multirate systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.4.1 Variable Processing Gain (VPG) systems . . . . . . . . . . . . 11 2.4.2 Variable ChipRate (VCR) systems . . . . . . . . . . . . . . . 12 2.4.3 Multi-Code systems . . . . . . . . . . . . . . . . . . . . . . . . 13 3 SYSTEMMODEL 15 3.1 MC-CDMAsystems . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3.2 Variable Processing Gain (VPG) Systems . . . . . . . . . . . . . . . . 18 3.3 Variable ChipRate (VCR) Systems . . . . . . . . . . . . . . . . . . . 21 3.4 Multi-code Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 4 LMS-BASED ALGORITHMS 24 4.1 Two types ofMC-CDMAwithAdaptive AntennaArray . . . . . . . 24 4.2 Post-FFT type inAdaptive Antennas . . . . . . . . . . . . . . . . . . 24 4.2.1 VPGandVCRsystems . . . . . . . . . . . . . . . . . . . . . 24 4.2.2 Multi-code systems . . . . . . . . . . . . . . . . . . . . . . . . 27 4.3 Pre-FFT type inAdaptive Antennas . . . . . . . . . . . . . . . . . . 29 4.3.1 VPGandVCRsystems . . . . . . . . . . . . . . . . . . . . . 29 4.3.2 Multi-code systems . . . . . . . . . . . . . . . . . . . . . . . . 31 4.4 Adaptive Antenna with Code Adjustment . . . . . . . . . . . . . . . 33 4.4.1 Post-FFT type . . . . . . . . . . . . . . . . . . . . . . . . . . 33 4.4.2 Pre-FFT Type . . . . . . . . . . . . . . . . . . . . . . . . . . 34 4.5 Complexity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 5 SIMULATION RESULTS 36 6 CONCLUSIONS 46 LIST OF TABLES 4.1 The systemcomplex characteristic . . . . . . . . . . . . . . . . . . . . 35 5.1 Themultiplication numbers in our simulation case . . . . . . . . . . . 39 6.1 Variable construction I . . . . . . . . . . . . . . . . . . . . . . . . . . 47 6.2 Variable construction II . . . . . . . . . . . . . . . . . . . . . . . . . 48 LIST OF FIGURES 3.1 MC-CDMAtransmitter block diagram . . . . . . . . . . . . . . . . . 18 3.2 VPG_MC-CDMA . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 3.3 The instance of dual-user systemratio 3:4 . . . . . . . . . . . . . . . 20 3.4 VCR_MC-CDMA . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 3.5 Multi-code_MC-CDMA . . . . . . . . . . . . . . . . . . . . . . . . . 23 4.1 A post-FFT type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 4.2 A pre-FFT type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 4.3 Adaptive antenna systems (post-FFT type) . . . . . . . . . . . . . . 28 4.4 Adaptive antenna systems (pre-FFTtype) . . . . . . . . . . . . . . . 31 5.1 LMS learning curve comparisons in post-FFT type for three multirate structures withGold code ( CP ) . . . . . . . . . . . . . . . . . . 40 5.2 LMS learning curve comparisons in post-FFT type for three multirate structures withGold code ( No CP ) . . . . . . . . . . . . . . . . 40 5.3 LMS learning curve comparisons in pre-FFT type for three multi-rate structures withGold code ( CP ) . . . . . . . . . . . . . . . . . . . . 41 5.4 LMS learning curve comparisons in pre-FFT type for three multi-rate structures withGold code ( No CP ) . . . . . . . . . . . . . . . . . . 41 5.5 The high-rate BER performance for the post-FFT type with Gold code ( CP ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 5.6 The high-rate BER performance for the post-FFT type with Gold code (No CP ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 5.7 The low-rate BER performance for the post-FFT type with Gold code ( CP ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 5.8 The low-rate BER performance for the post-FFT type with Gold code ( No CP ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 5.9 The high-rate BER performance for the pre-FFT type with Gold code ( CP ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 5.10 The high-rate BER performance for the pre-FFT type with Gold code ( No CP ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 5.11 The low-rate BER performance for the pre-FFT type with Gold code ( CP ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 5.12 The high-rate BER performance for the pre-FFT type with Gold code ( No CP ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4