Blind Source Separation and Equalization for MIMO-MC-CDMA communication systems

在適應性盲訊號分離與等化中Godard 或恒模數演算法(CMA)是最著名及廣泛被使用的演算法。首先可經由分析得知在多重輸入多重輸出的系統中使用恒模數演法等化，可以恢復原輸入訊號，消除符號間干擾(ISI)，及有效的壓抑源訊號間的干擾。此外，在有限脈衝響應(FIR)的系統滿足某些條件下，使用恒模數算法在有限脈衝響應的多輸入多輸出系統下(MIMO-CMA FIR)的等化器，可不用設定特定初值就能有效的恢復該系統的原輸入訊號。接著，提出恒模數系列的演算法在多載波分碼多工存取的多輸入多輸出(MC-CDMA MIMO)系統下的適應性盲訊號分離及等化處理。由分析可證實恒模數系列的演算法都可還原系統的所有輸入訊號，且在不用設定特定初值的情況下還原。另外，提出另一個接收端之架構，就是在等化器的前先將訊號做FFT轉換，在這所提到的恒模數系列的演算法有Sato 演算法、恒模數根基演算法CMA-based、改良型恒模數根基演算法和改良型恒模數演算法(MCMA)。恒模數根基演算法已被SHI Kun, and ZHANG Xudong [20]所提出，它改良了CMA，可在不須知道傳送端所使用何種調變下作運算，而所提出的改良型恒模數根基演算法是將恒模數根基演算法的不穩定性作改善且結合了MCMA的概念而提出。最後，經電腦摸擬後可證實分析及說明經恒模數系列的演算法在多載波分碼多工存取的多輸入多輸出(MC-CDMA MIMO)系統下的適應性盲訊號分離及等化後的效能。The Godard or constant modulus algorithm (CMA) [44] is perhaps the best known and the most popular scheme for adaptive blind source separation and equalization. First analyze reveals that the MIMO-CMA equalizer is able to recover one of the input signals, remove the inter-symbol interference (ISI), and suppress the inter-source interference. Furthermore, for the MIMO finite impulse response (FIR) systems satisfying certain conditions, the MIMO-CMA FIR equalizers are able to perfectly recover one of the system inputs regardless of the initial settings. Then propose a family of CMA for adaptive blind source separation and equalization for Multi-Carrier Code Division Multiple Access (MC-CDMA MIMO) systems. Theoretical analysis proves that the families of constant modulus algorithms are able to recover all system inputs simultaneously regardless of the initial settings. The Family of CMA mentioned has these of Sato、modify CMA-based algorithm、CMA-based algorithm and modify constant modulus algorithm (MCMA), where the CMA-based algorithm has already been proposed by SHI Kun, and ZHANG Xudong [33], it has improved the CMA, that unknown transmitter signal of modulation, and the modify CMA-based algorithm improve the unstability of CMA-based algorithm. Finally, computer simulation examples are presented to confirm analysis and illustrate the effectiveness of A Family of Constant Modulus Algorithms for Blind Source Separation and Equalization in MC-CDMA MIMO Systems.摘 要 i Abstract ii CONTENT iv LIST OF FIGURES vi Chapter 1 8 Introduction 8 Chapter 2 12 Concepts of MIMO OFDM-CDMA communication systems 12 2.1 Multiple-Input Multiple-Output (MIMO) 12 2.2 Orthogonal Frequency Division Multiplexing (OFDM) 14 2.3 OFDM combines MIMO 19 2.4 Code Division Multiple Access (CDMA) 20 2.4 OFDM-CDMA (MC-CDMA) 22 Chapter 3 26 System model 26 3.1 Multiple-Input Multiple-Output (MIMO) 26 3.2 MIMO-OFDM-CDMA 28 Chapter 4 37 Adaptive blind equalizers algorithms 37 4.1 Adaptive equalization 38 4.2 Blind Equalization 40 4.3 Blind Equalization Algorithms 40 4.3.1 Modify Sato Algorithm 42 4.3.2 Constant Modulus Algorithm (CMA) 44 4.3.3 Modified Constant Modulus Algorithm (MCMA) 45 4.3.4 New CMA-based 47 4.3.5 Modify CMA-based 48 4.4 Blind Equalization weight updates equation 49 Chapter 5 50 Simulations 50 Chapter 6 56 Conclusions 56 BIBLIOGRAPHY 5