多重輸入多重輸出MC-CDMA系統之偵測方法

Detection Methods for MIMO MC-CDMA Systems

邱善民(Shan-Min Chiu)

指導教授 ： 李彥文

國立暨南國際大學/科技學院/通訊工程研究所/碩士(2010年)

摘要

在多重輸入多重輸出多載波分碼多重接取(Multiple-Input Multiple-Output Multi-Carrier Code Division Multiple Access，MIMO MC-CDMA)系統中，其效能取決於偵測方法以及多重接取干擾(Multiple Access Interference，MAI)的消除與否。在單載波MIMO系統中，垂直貝爾實驗室分層空間時間(Vertical-Bell Labs Layered Space-Time，V-BLAST)偵測器被證實可以達到很高的資料傳輸速率。然而，在多載波的情況下會因為多重接取干擾及錯誤傳遞(Error Propagation)造成系統效能嚴重的下降而出現錯誤平層(Error Floor)現象。有研究提出，針對多重接取干擾作估測及消除，能有效提升系統錯誤率。本論文第一部分將會探討運用估測多重接取干擾之平行干擾消除(Parallel Interference Cancellation，PIC)偵測器及於下行MIMO MC-CDMA系統之可行性與效能比較。在符元層級偵測器(Symbol-Level Detector)的方面，由於同時進行等化與解展延之過程，因此必定會忽略多重接取干擾，使效能下降。本論文第二部分，在符元層級偵測器之後加上強制歸零(Zero Forcing，ZF)矩陣或是連續干擾消除(Successive Interference Cancellation，SIC)強制歸零，來改善符元層級偵測器之效能。

關鍵字

多重輸入多重輸出多載波分碼多重接取 ； 多重接取干擾 ； 平行干擾消除

並列摘要

For multiple-input multiple-output multi-carrier code division multiple access (MIMO MC-CDMA) systems, the multiple access interference (MAI) effect and the detection method used play a key role to the performance. It is known that in single-carrier MIMO systems, the vertical Bell labs layered space-time (V-BLAST) architecture can provide a very high data transmission rate. However, its performance is severely degraded in multi-carrier scenarios and results in a high error floor due to various MAI and error propagation effect. In previous studies, it is shown that the detector which cancels the MAI effectively can achieve a better performance. Based on this idea, in the first part of the thesis, we investigate a specially-designed parallel interference cancellation (PIC) detector to deal with the MAI in the downlink MIMO MC-CDMA system. Besides, it is understood that for a symbol-level detector which combines the equalization and dispreading process, a part of the MAI is unavoidably neglected and thus the performance can be degraded. In the second part of the thesis, we proposed a new symbol-level detector to enhance the performance. A zero-forcing (ZF) approach together with successive interference cancellation (SIC) is applied. Simulation results show that the error rate performance of the symbol-level detection can be improved.

並列關鍵字

MIMO MC-CDMA ； MAI ； PIC

參考文獻

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