Please use this identifier to cite or link to this item:
標題: 適用於多輸入多輸出正交分頻多工系統之頻域渦輪等化技術
Frequency-Domain Turbo Equalization for MIMO OFDM systems
作者: 鍾奇洋
Chung, Chi-Yang
關鍵字: 軟式決策反饋等化器
multilevel modulation
turbo equalization
出版社: 通訊工程研究所
引用: [1]V. Namboodiri, H. Liu, and P. Spasojevi`c, “Low complexity turbo equalization for mobile MIMO OFDM systems,” accepted in ICCSP 2011. [2]C. Douillard et al.,“Iterative correction of intersymbol interference: Turbo-equalization”, ETT, Vol.6, No. 5, pp. 507–511, Sep.-Oct. 1995. [3]C. Berrou, A. Glavieux, and P. Thitimajshima, “Near Shannon limit error-correcting and decoding: turbo codes,” in Proc. IEEE Int. Conf. Commun., vol.2, May, 1993, pp.1064-1070. [4]H. Lou and C. Xiao, “Soft decision feedback turbo equalization for multilevel modulations,” IEEE Trans. Signal Process., vol. 59, no. 1, pp. 186– 195, Jan. 2011. [5]R. R. Lopes and J. R. Barry, “The soft-feedback equalizer for turbo equalization of highly dispersive channels,” IEEE Trans. Commun., vol. 54, pp. 783–788, May 2006. [6]S. Talakoub, L. Sabeti, B. Shahrrava, and M. Ahmadi, “An Improved Max-Log-MAP Algorithm for Turbo Decoding and Turbo Equalization,” IEEE Trans. VOL. 56, NO. 3, JUNE 2007 [7]Shu Lin, and Daniel J. Costello, “Error Control Coding ,” Pearson Prentice Hall, 2004 [8]Imad Barhumi, “decision feedback turbo equalization for OFDM over doubly selective channel.” College of Engineering-UAE university, P.O.Box 17555 Al Ain, UAE [9]S. Ahmed, T. Ratnarajah, M. Sellathurai and Colin F. N. Cowan, “Iterative Receivers for MIMO-OFDM and Their Convergence Behavior.” IEEE Trans., VOL. 58, NO. 1, JANUARY 2009. [10] M. Tuchler, A. C. Singer, and R. Koetter, “Minimum mean square error equalization using a priori information,” IEEE Trans. Signal Process., vol. 50, no. 3, pp. 673–683, Mar. 2002. [11] A. Dejonghe and L. Vanderdorpe, “Turbo equalization for multilevel modulation: An efficient low-complexity scheme,” in Proc. IEEE Int. Conf. Commun., 2002, vol. 3, pp. 1863–1867. [12] B. Lu, G. Yue, and X. Wang, "Performance analysis and design optimization of LDPC-coded MIMO-OFDM systems," IEEE Trans. Signal Proc., vol. 52, no. 2, pp. 348 - 361, Feb. 2004. [13]S. ten Brink, “Convergence behavior of iteratively decoded parallel concatenated codes,” IEEE Trans. Commun., vol. 40, pp. 1727–1737, Oct. 2001. codes,” IEEE Trans. Commun., vol. 40, pp. 1727–1737, Oct. 2001. [14]H. Lou, C. Xiao and A. Rafati “Low-Complexity Soft-Decision Feedback Turbo Equalization for MIMO Systems With Multilevel Modulations” IEEE Trans. Vehicular Technology, vol. 60, no. 7, pp. 3218– 3227, Sep. 2011. [15]S. ten Brink, “Convergence behavior of iteratively decoded parallel concatenated codes,” IEEE Trans. Commun., vol. 40, pp. 1727–1737, Oct. 2001. [16]R. R. Lopes, “Iterative estimation, equalization and decoding,” Ph.D. dissertation, School of Electr. Comput. Eng., Georgia Inst. Technology, Atlanta, GA, 2003.School of Electr. Comput. Eng., Georgia Inst. Technology, Atlanta, GA, 2003. [17]M. Tuchler, R. Koetter, and A. C. Singer, “Turbo equalization: Principles and new results,” IEEE Trans. Commun., vol. 50, no. 5, pp. 754–767, May 2002. [18]P. Vila et al., “Reduced-complexity M-ary decoders for turbo-equalization,” presented at the 2nd Int. Symp. Turbo Codes Related Topics, Brest, France, Sep. 4–7, 2000. [19]X. Wang and H. V. Poor, “Iterative (turbo) soft interference cancellation and decoding for coded CDMA,” IEEE Trans. Commun., vol. 47, no. 7, pp. 1046–1061, Jul. 1999. [20]J. G. . New York: McGraw-Hill, 2001.
摘要: The mainly idea of this paper, we using iterative soft decision feedback equalization (SDFE) in frequency-domain (FD) for multiple-input–multiple-output (MIMO) Orthogonal frequency division multiplexing (OFDM) communication system transmission over multi-path propagation channels. Error propagation can seriously affect the performance of an adaptive decision feedback equalization (ADFE), especially when operated in inter-symbol interference (ISI) channel environments. Error propagation on the performance of the equalizer effect will be more obvious. So we using iterative SDFE not only suitable for multilevel modulation systems employing turbo equalization, but also using SDFE algorithm offers a novel approach to combat error propagation. Its equalization coefficients are chosen to minimize the mean-squared error (MMSE) between the transmitted symbol and equalizer output, used to determine the equalizer coefficients. However, under a Gaussian approximation to the a priori information and the SDFE output. Both the output of an equivalent AWGN channel, expressions for the a posteriori log likelihood ratio (LLR) and the extrinsic LLR are derived for multilevel modulation. In addition, we used irregular low-density parity check codes (LDPC) compared with the turbo codes, the regular LDPC codes performance better than turbo codes of the iterative receivers. And results show the performance of the using equalization scheme significantly improves when higher order constellations are used for MMSE-LE
本文主要提出一個在多徑傳播(Multi-path propagation)環境影響下,適用於多輸入多輸出-正交分頻多工(Multi-input Multi-output Orthogonal frequency-division multiplexing;MIMO-OFDM)通訊系統之頻域(Frequency domain)迭代軟式決策反饋等化器(Iterative soft decision feedback equalizer;ISDFE)。因錯誤傳播(Error propagation)會嚴重的影響適應性決策反饋等化器(Adaptive decision feedback equalizer;ADFE)的效能,特別是等化器工作於符際干擾(inter symbol interference,ISI)存在的通道環境中,錯誤傳播對等化器的效能影響會更明顯。本文所提出的迭代軟式決策反饋等化器(SDFE)不僅適用在多階調變(Multi-level modulation)系統,亦可消除錯誤傳播。於迭代等化運算過程中,使用等化器所輸出的傳送符元預估值與傳送符元做最小均方誤差(Minimum Mean-Square Error, MMSE)運算,用以決定等化器係數。然而,事後資訊(a posterior information)對數似然機率(log-likelihood ratio;LLR)和外部資訊(extrinsic information )對數似然機率於多階調變下的推導之假設為事前資訊(a priori information)和軟式決策反饋等化器(SDFE)的輸出值近似為等效高斯通道之輸出值。此外,從模擬的結果可以看出,不規則低密度查核碼(irregular low-density parity-check;irregular LDPC)相較於渦輪碼(Turbo code),有較佳的效能表現;另外,在高階調變下,本文所提出的等化器相較於最小均方差線性等化器(MMSE-LE)有更好的效能。
其他識別: U0005-2407201315081400
Appears in Collections:通訊工程研究所



Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.