適用於多重輸入多重輸出正交分頻多工系統之低複雜度訊號偵測法

Reduced Complexity Signal Detection Method in MIMO-OFDM System

吳佳穎(Jia-Ying Wu)

指導教授 ： 魏學文

國立暨南國際大學/科技學院/電機工程學系/碩士(2012年)

摘要

在高速移動的環境下，時變的通道會破壞正交分頻多工（Orthogonal frequency division multiplexing，OFDM）系統子載波間的正交性，進而產生子載波間的干擾(inter-carrier interference, ICI)，造成嚴重的信號檢測錯誤。在諸多應用在OFDM系統中之信號檢測法中，具有良好ICI抑制能力的SIC（Successive interference cancellation）演算法已被證實可以有效地提升信號檢測之正確性，然而其缺點是SIC的計算複雜度與OFDM子載波數目成正比關係，而通常OFDM系統均採用很高的子載波數目，因此使得SIC無法實用於OFDM系統中。基於此，本實驗室發展出qSIC演算法，並證明qSIC演算法於SISO-OFDM系統中，可以很低的運算複雜度在高正規化都普勒環境中達成近似SIC的效能。由於在多輸入多輸出正交分頻多工(MIMO-OFDM)系統中採用SIC所增加的運算複雜度變得更不切實際，為此，本論文探討改良qSIC演算法以應用在MIMO-OFDM系統中之可行性。

關鍵字

高速移動的環境 ； 正交分頻多工 ； 多輸入多輸出 ； 單輸入單輸出 ； qSIC

並列摘要

In high-speed mobile environments, the time-variant channel will destroy the orthogonality among the subcarriers in orthogonal frequency division multiplexing (OFDM) system. Thus, the time-variant channel will cause serious signal detection error. The successive interference cancellation (SIC) algorithm is one of the signal detection methods applied to OFDM system and has excellent performance for mitigating the ICI. And it has has been proved to be effective to upgrade the signal detection accuracy. However, the complexity of SIC is proportional to the number of subcarriers and OFDM system usually adopts large subcarrier number. For this reason, the realization of the detector becomes impractical. Therefore, the qSIC algorithm had been developed. For single-input single-output OFDM (SISO-OFDM) system, the qSIC algorithm only needs low computational complexity to achieve the performance that closes to SIC algorithm in high normalized Doppler shift environment. For multiple-input multiple-output OFDM (MIMO-OFDM) systems, the computational complexity of signal detection will be much greater. In this paper the qSIC algorithm is investigated for MIMO-OFDM systems.

並列關鍵字

OFDM ； SIC ； MIMO-OFDM ； qSIC ； SISO-OFDM

參考文獻

[1] J. A. C. Bingham, “Multicarrier modulation for data transmission: An idea whose time has come,” IEEE Comm. Mag., vol. 28, pp. 5-14, May 1990

[2] Y. Li and L. J. Cimini, "Bounds on the interchannel interference of OFDM in time-varying impairments," IEEE Trans. Comm., vol. 49, pp. 401-404, Mar. 2001.

[3] W. G. Jeon, K. H. Chang, and Y. S. Cho, "An equalization technique for orthogonal frequency-division multiplexing systems in time-variant multipath channels," IEEE Trans. Comm., vol. 47, pp. 27-32, Jan. 1999.

[4] X.N. Tran, T. Fujino, “Groupwise successive ICI cancellation for OFDM systems in time-varying channels,” in Proc. of the 5th IEEE International Symposium on Signal Processing and Information Technology, pp. 489-494 Dec.2005.

[5] P. W. Wolniansky, G. J. Foschini, G. D. Golden, and R. A. Valenzuela, “V-BLAST: An architecture for realizing very high data rates over the rich-scattering wireless channel,” in Proc. IEEE ISSSE’98, pp. 295-300, 1998.