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標題: 正交分頻多工分碼多重進接通訊之適應性渦輪碼接收機之實現
Implementation of Adaptive Turbo Receivers for OFDM-CDMA Communications
作者: 袁雋瑋
Yuan, Chun-Wei
關鍵字: Turbo Decoder;渦輪解碼器;Decision-Directed Equalizer;Turbo Equalizer;適應性等化器;渦輪等化器
出版社: 電機工程學系所
引用: [1] Kaiser S., “OFDM code division multiplexing in fading channels,” IEEE Trans. on Comm., vol.50, pp.1266-1273, Aug. 2002. [2] Kaiser S. and Hagenauer J., “Multi-Carrier CDMA with Iterative Decoding and Soft-Interference Cancellation,” in Proc. IEEE Global Telecommunications Conference (GLOBECOM'97), Phoneix, USA, pp. 6-10, Nov. 1997. [3] C. Berrou, A. Glavieux, and P. Thitimajshima, “Near Shannon limit error-correcting coding and decoding: Turbo codes,” in Proc. IEEE Int. Conf. on Communications, Geneva, Switzerland, May 1993. [4] L. R. Bahl et al., “Optimal decoding of linear codes for minimizing symbol error rate,” IEEE Trans. Inform. Theory, vol. IT-20, pp. 284-287, Mar. 1974. [5] S. Lin and J. J. Costello, Error Control Coding. 2nd Ed., Upper Saddle River, NJ: Pearson Prentice-Hall, 2004 [6] C. Douillard, M. Jezequel, C. Berrou, A. Picart, P. Didier, and A. Glavieux, "Iterative correction of intersymbol interference: Turbo equalization," European Trans. on Telecomm., vol. 6, pp. 507--511, Sep-Oct 1995. [7] X. Wang and H. Poor, "Iterative (turbo) soft interference cancellation and decoding for coded CDMA," IEEE Trans. on Comm., vol. 47, no. 7, pp. 1046--1061, 1999. [8] M. Tuchler, R. Koetter, and A. Singer, "Turbo equalization: principles and new results," IEEE Trans. on Comm., vol. 50, pp. 754--767, May 2002. [9] M. Tüchler, A. Singer, and R. Kötter, “Minimum mean squared error (MMSE) equalization using priors,” IEEE Trans. Signal Processing, vol. 50, pp. 673-683, Mar. 2002. [10] Fang-Biau Ueng, Li-Der Jeng, Jun-Da Chen and Jia-Yu Yang, “Adaptive Receivers for DS/CDMA Multiuser Communication in Multipath Fading Channels,” IEICE Trans. on Comm., vol.E88-B, no.2, pp.687-697, February 2005. [11] S. Haykin, Adaptive Filter Theory, 4th Edition, Upper Saddle River, NJ: Pearson Prentice-Hall, 2002 [12] Z. Wang, H. Suzuki, and K. K. Pahri, “VLSI implementation issues of turbo decoder design for wireless applications”, Proc. IEEE Int. Workshop Signal Processing Syst., 1999, pp. 503-512.
在無線通訊系統中,利用錯誤更正碼來提高資料傳輸的可靠度已經是不可或缺的方法。採用迭代解碼法的渦輪碼已經被證明在較低的訊雜比時有非常低的位元錯誤率,在現代或下一代的寬頻無線通訊系統都已採用渦輪碼作為錯誤更正碼。在本研究中,我們將評估正交分頻多工-分碼多重存取(OFDM-CDMA)通訊系統在多路徑衰減通道中下行鏈路之接收機性能。正交分頻多工分碼多重存取系統中使用適應性等化器與渦輪解碼器。我們使用最小均平方誤差演算法(LMS)作為適應性等化器的適應性演算法。我們研究兩種接收機架構:第一種是傳統的方法,即等化器與渦輪解碼器獨立運作的架構(Equalizer Disjointed with Turbo Decoder)。第二種架構稱為等化器與渦輪解碼器聯合運作的架構(Equalizer Jointed with Turbo Decoder),此架構結合等化器和渦輪解碼器,將渦輪解碼器產生的外部資訊(Extrinsic Information)回饋到適應性等化器中當作期望訊號。最後,我們亦在此論文中以硬體描述語言Verilog HDL實現此兩種架構,並比較它們的效能。

In wireless digital communication systems, error-correcting coding is indispensable to enhance the channel reliability. Turbo code with iterative decoding has been proven to render very low bit error rate in low signal-to-noise ratio and has been adopted in contemporary and next generation wireless communication systems. In this work, the receivers with adaptive equalizer and turbo decoder are investigated for orthognal frequency division multiple-code division multiple access (OFDM-CDMA) systems over multipath channels. The LMS algorithm is used as the adaptive algorithm for dispreading equalizer. Two receiver architectures are investigated: The first one is the traditional receiver called equalizer disjointed with turbo decoder. The second receiver architecture is equalizer jointed with turbo decoder, where the extrinsic information from turbo decoder is sent back to adaptive equalizer as the desired information. Finally, we implement theses two architectures with Verilog HDL, and compare their performance
其他識別: U0005-3101201001105500
Appears in Collections:電機工程學系所

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