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研究生:李裕銘
研究生(外文):Yu-Ming Le
論文名稱:正交分頻多工系統下之通道估測方法研究
論文名稱(外文):Study of channel estimation methods for OFDM systems
指導教授:王瑞騰
指導教授(外文):Jui-Ten Wang
學位類別:碩士
校院名稱:國立暨南國際大學
系所名稱:通訊工程研究所
學門:工程學門
學類:電資工程學類
論文種類:學術論文
論文出版年:2009
畢業學年度:97
語文別:中文
論文頁數:55
中文關鍵詞:正交分頻多工系統部分級數通道近似通道估測最小平方最小均方誤差
外文關鍵詞:orthogonal frequency division multiplexing (OFDM)fraction taps channel approximation (FTCA)channel estimationLSMMSE
相關次數:
  • 被引用被引用:2
  • 點閱點閱:253
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  • 下載下載:59
  • 收藏至我的研究室書目清單書目收藏:0
在本篇論文中,我們研究使用於正交分頻多工(orthogonal frequency division multiplexing ,OFDM)系統下,以部分級數通道近似(fraction taps channel approximation ,FTCA)通道模型為基礎的一種通道估測法。此研究的通道估測法,是根據參數通道近似模型來改善通道估測。在我們系統中,首先在時域及頻域插入導頻載波(pilot subcarriers),然後再使用最小平方(least square ,LS)與最小均方誤差(minimum mean square error ,MMSE)估測法來得到導頻載波的通道響應。我們對FTCA通道模型之LS估測法及MMSE估測法進行模擬;且為了互相比較,先前提出能有效抗雜訊及減少運算複雜度的修正型LS與修正型MMSE估測法,也對此兩種估測法進行模擬。透過模擬結果我們發現在通道估測錯誤率上,使用FTCA通道模型之LS及MMSE估測法為較低於修正型LS與修正型MMSE估測法,且發現搭配FTCA通道模型的估測法可解決在高訊雜比環境中所出現的錯誤溢位(error floor)問題。
In this thesis, we study a channel estimation method that is based on the fraction taps channel approximation (FTCA) channel model for the OFDM system.The studied channel estimation method is an improved channel estimation method based on a parametric channel approximation model. In our system, the pilot subcarriers are first inserted in the time domain and the frequency domain,then the least square (LS) estimator and the minimum mean square error (MMSE)
estimator are used to estimate the channel response of the pilot subcarriers.We execute simulations for the LS estimator and the MMSE estimator with the FTCA channel model. And for comparison, we also execute simulations for the modified LS estimator and the modified MMSE estimator, which were previously proposed for combating the noise effect and reducing the computational complexity. We found that the LS estimator and the MMSE estimator with the FTCA channel model can result in less channel estimation error than the modified LS estimator and the modified MMSE estimator. Also, we found that
the estimators with the FTCA channel model can eliminate the error floor problem at high SNR.
目錄

致謝....................................................................I
中文摘要...............................................................II
英文摘要..............................................................III
目錄...................................................................IV
圖目錄................................................................VI
表目錄...............................................................VII

第一章 緒論.............................................................1
1.1前言............................................................1
1.2研究目的與動機..................................................1
1.3論文架構........................................................2
第二章 正交分頻多工系統架構.............................................3
2.1正交分頻多工系統簡介............................................3
2.2離散傅立葉反轉換(IDFT)和離散傅立葉轉換(DFT).....................4
2.3正交分頻多工系統基本架構....................................5
第三章 無線傳輸通道模型.............................................8
3.1無線傳輸通道概數............................................8
3.2小範圍衰減通道模型.........................................10
3.3 Jakes’Channel Model.......................................18
第四章 OFDM系統下之FTCA通道估測...................................22
4.1參數通道簡介...............................................22
4.2 FTCA通道模型...............................................23
4.3 導頻載波(pilot)之排序......................................25
4.4 LS與MMSE通道估測......................................28
4.4.1 LS估測法(LS Linear)............................28
4.4.2 MMSE估測法.......................................30
4.4.3 修正型LS與修正型MMSE估測法........................31
修正型LS估測法(Modified LS).....................31
修正型MMSE估測法(Modified MMSE)...................32
4.5部分級數通道近似(FTCA)通道估測.............................33
4.5.1 FTCA-LS估測法........................................34
4.5.2 FTCA-MMSE估測法......................................36
第五章 模擬結果與分析..............................................39

第六章 結論..........................................................53

參考文獻...........................................................54
參考文獻

[1] S. K. Wilson, R. E. Khayata, and J. M. Cioffi, “16-QAM modulation
with orthogonal frequency division multiplexing in a Rayleigh-fading
environment,” in Proc. IEEE Vehicular Technology Conf., Stockholm,
Sweden, Jun. 1994, vol. 3, pp. 1660–1664.

[2] Baoguo Yang, Khaled Ben Letaief, Roger S.Cheng,and Zhigang Cao, ”Channel
estimation for OFDM transmission in multipath fading channels based on
parametric channel modeling ”IEEE TRANSACTIONS ON COMMUNICATIONS, VOL.
49,NO.3,MARCH 2001.

[3] J.-J. van de Beek, O.Edfors, and M.Sandell, ”On channel estimation in OFDM systems,” in Proc. IEEE Vehicular Technology Conf.,Jul.1995,vol.
2,pp.815-819.

[4] Naquan Chen, Jianhua Zhang, and Ping Zhang, “Improved channel estimation based on parametric channel approximation modeling for OFDM systems,
” IEEE TRANSACTIONS ON BROADCASTING, VOL.54, NO. 2,JUNE 2008.

[5] Sinem Coleri, Mustafa Ergen, Anuj Puri, and Ahmad Bahai, ”Channel estimation techniques based on pilot arrangement in OFDM systems,” IEEE TRANSACTIONS ON BROADCASTING,VOL.48,NO.3,SEPTEMBER 2002.

[6] Wei Zhang, Xiang-Gen Xia, and P. C. Ching, ”Optimal training and pilot
pattern design for OFDM systems in Rayleigh fading,” IEEE TRANSACTIONS
ON BROADCASTING,VOL.52,NO.4,DECEMBER 2006.

[7] M.-H. Hsieh and C.-H. Wei, “Channel estimation for OFDM systems
based on comb-type pilot arrangement in frequency selective fading
channels,” IEEE Trans. Consumer Electronics, vol. 44, pp. 217–225,
Feb. 1998.

[8] Ming-Xian Chang, and Yu T.Su, ”Performance analysis of equalized OFDM
systems in Rayleigh fading,” IEEE TRANSACTIONS ON WIRELESSCOMMUNICATIONS
,VOL.1,NO.4,OCTOBER 2002.

[9] J. K. Moon and S. I. Chol, “Performance of channel estimation methods
for OFDM systems in a multipath fading channels,” IEEE Trans. Consumer
Electronics, vol. 46, pp. 161–170, Feb. 2000.

[10] S. M. Kay, Fundamentals of Statistical Signal Processing: Estimation
Theory. Englewood Cliffs, NJ: Prentice-Hall, 1993.
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