臺灣博碩士論文加值系統

針對無線通訊環境傳輸，本論文研究遞迴最小平方演算法 (RLS) 應用於各種適應性等化器，其中包含線性橫向等化器，以及非線性決策回授等化器。我們使用多重路徑衰減通道評估各種適應等化器的效能，評估演算法中的遺忘參數和等化器的階數對於效能的影響，以及分析不同演算法對於收斂速度和錯誤變異量的影響；最後與理論驗證模擬結果的正確性。在本論文中，我們採用Simulink建立了一個RLS等化器的測試平台，這平台中包含了各調變及通道編碼技術。在未來的研究上，這樣的平台可提供我們快速的分析出一個新等化器演算法的錯誤率和收斂速度等效能。

The adaptive equalizers using the recursive least-squares (RLS) algorithm is investigated for wireless communication systems. Both linear transversal equalizer and non-linear decision feedback equalizer (DFE) with RLS algorithm are evaluated in multipath fading channel model. The influence of some important parameters, such as tap number of the adaptive equalizers, and forgetting factor of the algorithm, is examined. Then, the rate of convergence and error variance with different algorithm is analyzed. Finally the validity of the theoretical results is verified through computer simulations. Above all, a test bed for the RLS equalizer with modulation and channel coding is built by using Simulink. In the future work, we can use this test bed to fast analysis the performance in terms of BER, MSE and convergence speed for any proposed adaptive equalizer algorithm.

ACKNOWLEDGMENT I
摘要 II
ABSTRACT III
CONTENTS IV
LIST OF FIGURE VI
LIST OF TABLE VII
CHAPTER 1 INTRODUCTION 1
1.1 Introduction 1
1.2 Organization 2
CHAPTER 2 CHANNEL INTERFERENCE 3
2.1 Introduction 3
2.2 The Additive Noise Channel 4
2.2.1 AWGN Channel 5
2.3 The Linear Filter Channel 7
2.3.1 Bandlimited Channel 7
2.4 The Linear Time-variant Filter Channel 8
2.4.1 Fading Channel 10
2.4.2 Rician Channel 12
2.4.3 Rayleigh Channel 13
2.5 Digital Modulation 14
CHAPTER 3 ILLUSTRATION OF PRINCIPLES 17
3.1 Transversal Filter 17
3.2 Wiener Filter 18
3.3 Adaptive Equalizer 20
3.4 Decision Feedback Equalizer 23
3.5 RLS Algorithm 25
3.5.1 The Matrix Inversion Lemma 27
3.5.2 The Exponentially Weighted RLS Algorithm 27
3.6 Contrast of LMS and RLS Algorithm 29
CHAPTER 4 SIMULATION AND RESULTS 32
4.1 Introduction to Simulation Tool 32
4.2 Building the Simulation Model 32
4.3 Comparison of Experimental Results 36
4.3.1 Experiment 1: Effect of Equalizer Length Parameter 36
4.3.2 Experiment 2: Effect of Forgetting Factor Parameter 38
4.2.3 Experiment 3: Effect of Equalizer Length Parameter for Convergence 41
4.2.4 Experiment 4: Effect between the Linear Equalizer and DFE in Channel 42
4.2.5 Experiment 5: Effect of DFE in Rayleigh Fading Channel 48
4.4.6 Experiment 6: Effect of DFE with Channel Coding 51
CHAPTER 5 CONCLUSIONS 54
REFERENCES 55

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