Adaptive Receivers for SIMO/MIMO MC-CDMA Communication Systems

本論文研究在多重路徑衰退通道下無線通訊系統中空時訊號接收器的設計方式及性能分析，主要的成果與貢獻分為以下三部份：首先在多輸入多輸出直序分碼多工(MIMO DS/CDMA)系統在多重路徑的環境下，提出以TLS與ESPRIT演算法為基礎的檢測器。緊接著又將ESPRIT與LMS演算法結合發展為另一種適應性接收器，可有效壓制多重路徑的影響。第二部份則在多輸入多輸出多載波分碼多工(MIMO MC-CDMA)系統在多重路徑的環境下，分別提出以最小均方誤差(LMS)及遞回最小均方誤差(RLS)演算法為基礎之適應性接收器架構。同時也利用最小均方誤差及遞回最小均方誤差演算法來調整展頻碼係數，此項設計有效的降低了演算法運算上的複雜性。第三部份為在多速率MC-CDMA系統，提出三種多速率的方法：可變程序增益(VPG)、可變碼速率(VCR)和多重碼系統。我們將考慮在後快速富立葉型式(post-FFT)與前快速富立葉型式(pre-FFT)經由多重路徑的環境時，各種不同的適應性接收機架構分析。In this dissertation, we will discuss the design and performance of space-time processing receivers in wireless communications with multipath fading channel. The main achievement and contribution are divided into three following components: Firstly, we employ the total least-squares (TLS) method and Estimation of Signal Parameter via Rotational Invariance Techniques (ESPRIT) to construct the detector structures for the multiple-input-multiple-output direct sequence code division multiple access (MIMO DS/CDMA) systems under multipath fading. We use the LMS algorithm in the ESPRIT-based detectors to develop adaptive receivers and also to suppress the effect of multipath. Secondly, we employ the least mean square (LMS) algorithm and recursive least square (RLS) algorithm to construct the adaptive receiver structures for MIMO multicarrier CDMA (MC-CDMA) systems under multipath fading. Using LMS and RLS algorithm include adjusting the spreading code coefficients. Our proposed adaptive receiver structures are designed for the sake of diminishing complexity. Thirdly, we proposed three multi-rate methodologies-variable processing gain (VPG), variable chip rate (VCR) and multi-code systems in adaptive antenna receiver structures in multi-rate-MC-CDMA communication systems. We will concentrate on the construction of adaptive receivers for post-FFT and pre-FFT type with multipath fading channel.ACKNOWLEDGEMENT...i CHINESE ABSTRACT...ii ENGLISH ABSTRACT...iii CONTENTS...iv LIST OF FIGURES...viii LIST OF TABLES...xi 1 INTRODUCTION...1 1.1 Outline of Dissertation and Research Contributions...6 2 SYSTEM DESCRIPTION...8 2.1 DownlinkMIMOTransmitter SignalModel...8 2.1.1 DS/CDMASignalModel...8 2.1.2 MC-CDMASignalModel...10 2.2 Channel Model...12 2.2.1 SIMOChannelModel...12 2.2.2 MIMOChannelModel...13 2.3 DownlinkMIMOReceived SignalModel...14 2.3.1 DS/CDMA System...14 2.3.2 MC-CDMASystem...16 2.4 UplinkMultirateMC-CDMASystems...18 2.4.1 Variable Processing Gain (VPG) Systems...20 2.4.2 Variable Chip Rate (VCR) Systems...21 2.4.3 Multi-code Systems...23 3 ADAPTIVE RECEIVERS FOR MIMO DS/CDMA COMMUNICATION SYSTEMS...27 3.1 The Proposed LinearMultiuserDetectors...28 3.1.1 TLS Detector...28 3.1.2 ESPRITDetector...33 3.2 The Adaptive Receivers Based on the Proposed LMDs...39 3.2.1 LMS Receiver...40 3.2.2 ESPRIT Based LMS Receiver...43 3.2.3 Comparisons...43 3.3 Simulation Results...45 3.4 Conclusion...47 4 ADAPTIVE RECEIVERS FOR MIMO MC-CDMA COMMUNICATION SYSTEMS...56 4.1 NarrowbandAdaptive Receiver...57 4.1.1 LMS-BasedAlgorithm...57 4.1.1.1 Mean Square Error Analysis...59 4.1.1.2 NarrowbandWCFAdaptive Receiver...61 4.1.1.3 MSEAnalysis of WCF...62 4.1.2 RLS-Based Algorithms...63 4.1.2.1 Analysis of RLS-basedAdaptive Antenna...66 4.1.2.2 WCFUpdate Equations...69 4.1.2.3 Analysis of RLSWCF...71 4.2 WidebandAdaptive Receiver...73 4.3 Simulation Results...80 4.4 Conclusions...81 5 ADAPTIVE ANTENNAS FOR MULTI-RATE MC-CDMA MULTIUSER COMMUNICATION SYSTEMS...87 5.1 The ProposedMultiuser Receivers...88 5.1.1 MLDetector...90 5.1.2 DecorrelatingDetector...91 5.1.3 LMMSEDetector...91 5.2 The Proposed Adaptive Receivers...91 5.2.1 Post-FFTTypeAdaptive Receiver...92 5.2.1.1 VPGandVCRsystems...92 5.2.1.2 Multi-code systems...94 5.2.2 Pre-FFT Type Adaptive Receiver...95 5.2.2.1 VPGandVCRsystems...95 5.2.2.2 Multi-code systems...97 5.2.3 Adaptive Receiver with Code Adjustment...98 5.2.3.1 Post-FFT Type...98 5.2.3.2 Pre-FFT Type...99 5.3 Simulation Results...99 5.4 Conclusions...10