本論文主要為探討OFDM系統在UWB通道下，領導式通道估測的方法對於不同通道變換下之分析，以及領導訊框個數對於執行效能的影響。領導式通道估測的方法主要包含LS估測法和LMS演算法，在通道參數固定之下，此二方法皆能達到良好的執行效能，且其執行效能還會隨著領導訊框的數量而增加。基本上LS估測法本身並不考量通道變化的，而LMS演算法雖能適應通道的變化，但僅適用於通道參數緩慢變化時。但如果通道的變化造成通道參數大幅改變，LMS演算法無法得到很好的通道參數調適，導致效能不佳，而LS估測法因無法判斷通道變化，只能以單筆的領導符碼來估測通道參數，若通道變換率極為緩慢時，其執行效能並不佳。為了在動態通道之下能夠達到更好的執行效能，本論文提出了改良式LS估測法，在原有LS估測法中加進通道變化點的判斷法則，以期能夠有效的應用領導符號，改善系統效能。最後，將本方法應用於在UWB通道下之OFDM系統，以電腦模擬方式，驗證其結果。

This thesis is mainly to research into the performance of methods of pilot channel estimation over the UWB channel. The primary methods of pilot channel estimation include LS method and LMS method. Both of them have good performances under fixed channel, and the system performances increase with the amount of pilot frames. Basically, LS method does not consider the variations of the channel. Although LMS method can adopt the channel variations, it is limited to the case that the channel parameters change slowly. If the channel parameters change extensively, there won’t be any good performances by LMS method. Under this circumstance, we can only use single pilot symbol for the LS method to estimate the channel parameters, which results in the poor performance of systems for slowly changing channels. In order to get better performance in the dynamic changing channel, this thesis proposes an improved LS method by applying the addition rules for predicting the changing points of the channel. This method can effectively use all pilot frames to improve the system performances. At the end of the thesis, we apply our method to the OFDM system in UWB channel to verify its performance.

中文摘要 i
英文摘要 ii
誌謝 iii
目錄 iv
表目錄 vi
圖目錄 vii
第一章 緒論 1
1.1 前言 1
1.2 研究動機與方法 2
1.3 各章內容 2
第二章 UWB通道原理及OFDM相關知識 4
2.1 OFDM動作原理 4
2.1.1 IDFT/DFT 6
2.1.2 OFDM傳送湍分析 7
2.1.3 保護帶 8
2.1.4 通道效應的影響 11
2.1.5 OFDM的優點 11
2.1.6 OFDM的缺點 11
2.2 UWB訊號 12
2.3 多路徑傳播影響 13
2.3.1 總多路徑影響 14
2.4 UWB通道 15
第三章 領導式通道估測應用於OFDM系統 25
3.1 OFDM系統 25
3.1.1 OFDM-AWGN系統 26
3.1.2 OFDM-UWB系統 28
3.1.3 電腦模擬平均位元錯誤率 30
3.2 領導符碼樣式 31
3.2.1 電腦模擬比較各種領導符碼樣式的執行效能 35
3.3 通道估測方法 36
3.3.1 LS估測法 37
3.3.2 LMS演算法 40
3.3.3 電腦模擬LS估測法於不同數量之領導訊框 41
3.3.4 電腦模擬LS估測法於不同環境之UWB通道 44
3.3.5 電腦模擬LMS演算法之精確度 47
3.3.6 電腦模擬LMS演算法不同數量之領導訊框 49
3.3.7 電腦模擬LS估測法與LMS演算法於動態通道中 51
3.4 改良式領導式通道估測演算法 57
3.5 電腦模擬 60
3.5.1 電腦模擬領導訊框數量對於改良式LS估測法
之影響 66
3.5.2 電腦模擬適應性改良式LS估測法之執行效能 72
3.5.3 電腦模擬適應性改良式LS估測法於分佈通道
之位元錯誤率分析 76
第四章 結論與未來發展 82
參考文獻 84

[1] Z. Irahhauten, J. Dacuna, G.J.M. Janssen, and H. Nikookar, ”UWB Channel Measurements and Results for Wireless Personal Area Networks Applications, ” The European Conference, Oct. 2005, pp 189-192.
[2] M. D. Benedetto and G. Giancola, Understanding Ultra Wide Band Radio Fundamentals, Prentice Hall PTR, 2004.
[3] J. A. C. Bingham, "Multi-carrier modulation for data transmission: An idea whose time has come," IEEE Comm. Magazine, pp. 5-14, May 1990.
[4] C. H. Hsiao and M. Guizani, Next Generation Wireless Systems and Networks, Wiley, 2006.
[5] J. K. Cavers, Mobile channel characteristics, Boston Kluwer, 2000
[6] J. G. Proakis, Digital Communication, Fourth Edition, McGraw-Hill, 2001.
[7] S. Haykin, Communication Systems, Fourth Edition, Wiley, 2001.
[8] A. S. Bahai and B. R. Saltzberg, Multi-Carrier Digital Communications Theory and Applications of OFDM, New York, Kluwer Academic/Plenum Publishers, 1999.
[9] J.-J. van de Beek, O. Edfors, M. Sandell, S. k. Wilson, and P. O. Borjesson, ”On channel estimation in OFDM systems, ” in Proc. IEEE 45th Vehicular Technology Conf, vol. 46, no. 7, Jul. 1995, pp 815-819.
[10] A. Feng, Q. Yin, J. Zhang, and K. Deng, ”Blind Channel Estimation in Synchronous MC-CDMA System with Consideration of Carrier Offset Compensation, ” IEEE 55th Vehicular Technology Conf, vol. 2, no. 7, Spr. 2002, pp 660-664.
[11] M. J. Fernandez-Getino Garcia and S. Zazo and J. M. Paez-Borrallo, “Pilot patterns for channel estimation in OFDM,” IEEE Electronics Letters, vol. 36, no. 12, June. 2000, pp 1049-1050.
[12] S. Coleri, M. Ergen, A. Puri, and A. Bahai, ”Channel Estimation Techniques Based on Pilot Arrangement in OFDM Systems, ” IEEE Trans, vol. 48, no. 3, Sep. 2002, pp 223-229.
[13] B. Farhang-Boroujeny, Adaptive Filters Theory and Applications, Wiley, 1999.
[14] R. Prasad and S. Hara, "An overview of multi-carrier CDMA," in Proc. IEEE 4th Int. Symp. Spread Specturm Technique and Application Proc., pp. 107-114, Sept. 1996.
[15] W. Zou and Y. Wu, "COFDM: AN OVERVIEW," IEEE Trans. On Broadcasting, vol. 41, no. 1, pp. 1-8, Mar. 1995.
[16] L. Hanzo, M. Munster, B. Choi and T. Keller, OFDM and MC-CDMA for Broadband Multi-User Communications, WLANs and Broadcasting, New York, John Wiley & Sons, March 2004.
[17] R. D. Yates and D. J. Goodman, Probability and Stochastic Processes: A Friendly Introduction for Electrical and Computer Engineers, Wiley, 1999.
[18] 詹政道，使用FFT之MC-CDM系統於UWB通道下之效能分析，碩士論文，國立臺北科技大學電機工程系碩士班，台北，2006。
[19] A. Rorres, Elementary Linear Algebra, Eighth Edition, Wiley, 2000