使用於 SFBC OFDM 系統之半盲目通道追蹤以及改良型通道補償估測器

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研究生：	樊昱孝 Yu-Hsiao Fan
論文名稱：	使用於 SFBC OFDM 系統之半盲目通道追蹤以及改良型通道補償估測器 Semi-Blind SFBC OFDM Channel Estimation with an Improved Channel Compensation Scheme
指導教授：	張大中 Dah-Chung Chang
口試委員:
學位類別：	碩士 Master
系所名稱：	資訊電機學院 - 通訊工程學系在職專班 Executive Master of Communication Engineering
畢業學年度：	98
語文別：	中文
論文頁數：	69
中文關鍵詞：	通道追踨、半盲目、通道補償
外文關鍵詞：	cma, sfbc, ofdm, semi-blind, df
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OFDM 系統中通道估測方法一直被廣泛討論與研究。在本論文
中，我們採用半盲目的方法來研究 SFBC OFDM 系統通道的追蹤，
半盲目方法的好處在於不會使用太多的頻寬。所研究的方法在接收端追蹤通道時，依據當時通道的特性來選擇使用決策迴授機制或是改良式固定模數演算法(Modified Constant Modulus Algorithm)來進行估測，其中我們使用了一個自動切換方式。並且，修正的通道估測法使用線性內插或外插方式來進行補償。由模擬結果得知，如此切換的方式加上改良式的通道補償，比傳統僅使用決策迴授法或改良式固定模數演算法的效能更佳。

Channel estimation has been a widely studied research topic in OFDM systems. In this thesis, we consider the semi-blind approach for channel tracking used in space frequency block code (SFBC) MIMO-OFDM. The advantage of the semi-blind method is little occupancy of bandwidth. The proposed algorithm can estimate the channel response by using the conventional decision feedback scheme or a modified constant modulus algorithm (CMA) based on an automatic switching mechanism in terms of the channel status. Besides, a modified channel estimation method is performed by applying the interpolation or the extrapolation scheme for channel compensation. Simulation results show that the proposed switching method in combination with the modified channel compensation scheme outperforms the method using only decision feedback or the modified CMA.

目錄. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I
圖目錄. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . II
表目錄. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IV
第1 章序論. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 前言. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 大綱介紹. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
第2 章SFBC MIMO-OFDM 系統介紹. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1 SFBC 編碼方式介紹. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2 MIMO-OFDM 系統介紹. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
第3 章第三章SFBC MIMO-OFDM 之通道追蹤. . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1 使用Preamble 預估MIMO-OFDM 通道. . . . . . . . . . . . . . . . . . . 11
3.2 決策迴授機制等化器. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.3 MCMA 演算法. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
第4 章SFBC MIMO-OFDM 在通道追踨上的改良方法. . . . . . . . . . . . . . . . . . . . 22
4.1 半盲目通道追蹤與決策迴授機制之切換法則. . . . . . . . . . . . . . . 22
4.2 突然變動的偵測. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
4.3 錯誤發生的修正補償. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
第5 章模擬與分析. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
5.1 系統及通道模型參數設定. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
5.2 決策迴授機制平滑化參數對系統影響之模擬. . . . . . . . . . . . . . . 32
5.3 MCMA 中不同步階大小對系統影響之模擬. . . . . . . . . . . . . . . . 33
5.4 MCMA 與決策迴授機制切換之模擬. . . . . . . . . . . . . . . . . . . . . . 37
5.4.1 不同β 值切換對系統影響之模擬. . . . . . . . . . . . . . . . . . . . . 37
5.4.2 滑動視窗值對於影響系統切換之模擬. . . . . . . . . . . . . . . . . 40
5.5 偵測機制與補償來提昇通道追踨的效能. . . . . . . . . . . . . . . . . . . 46
5.6 通道追蹤演算法效能與位元錯誤率之模擬與分析. . . . . . . . . . . 48
第6 章結論與未來展望. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
參考文獻. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

                                

參考文獻
[1] K. Lee and D. Williams, “A space-frequency transmitter diversity
technique for OFDM systems,”in Global Telecommunications Conference,
vol. 3, Aug. 2000, pp. 1473–1477.
[2] S. Coleri, M. Ergen, A. Puri, and A. Bahai, “Channel estimation
techniques based on pilot arrangement in OFDM systems,”IEEE
Trans. Broadcasting, vol. 48, no. 3, pp. 223 –229, Sep. 2002.
[3] R. Grunheid, H. Rohling, J. Ran, E. Bolinth, and R. Kern, “Robust
channel estimation in wireless LANs for mobile environments,”in
Proc. IEEE Vehicular Technology Conf., vol. 3, Dec. 2002, pp.
1545–1549.
[4] S. Balasubramanian, B. Farhang-Boroujeny, and V. Mathews,
“Pilot embedding for channel estimation and tracking in OFDM systems,”
in Proc. IEEE Global Telecommunications Conf., vol. 2, Jan.
2004, pp. 1244–1248.
[5] M. Noune and A. Nix, “Impact of channel estimation errors on
the performance of DFE equalizers with space time block codes in
wideband fading channels,”in Wireless Communications and Networking
Conference, jun. 2007, pp. 2241–2246.
[6] L. Wang, F. Zhang, and A. B. Sesay, “STBC-DFE systems over
multipath fading channels,”in Electrical and Computer Engineering,
May 2006, pp. 1554–1557.
[7] I. Chahed, J. Belzile, and A. Kouki, “Blind decision feedback equalizer
based on high order MCMA,”in Proc. IEEE Canadian Conference
on Electrical and Computer Engineering., vol. 4, Nov. 2004,
pp. 2111–2114.
[8] M. Hassan, B. Sharif, W. L. Woo, and S. Jimaa, “Semiblind estimation
of time varying STFBC-OFDM channels using Kalman filter and CMA,”in Computers and Communications, vol. 2, Nov. 2004,
pp. 594–599.
[9] W. Chen, SFBC MIMO OFDM Channel Estimation with a Semiblind
Method. Master Thesis, Department of Communication Engineering,
National Central University, Jhongli Taiwan,July, 2009.
[10] C. M. Wu, The OFDM System with a Semi-Blind Channel Tracking
Algorithm. Master Thesis, Department of Communication Engineering,
National Central University, Jhongli Taiwan,July, 2008.
[11] J. Park, M. Oh, Y. Cho, and D. Park, “New channel estimation
scheme exploiting decision feedback symbols for OFDM systems,”
in IEEE Consumer Electronics, International Conference,
Feb. 2006, pp. 367–368.
[12] M. Chiani, “Introducing erasures in decision-feedback equalization
to reduce error propagation,”IEEE Transaction on Communications,
vol. 45, no. 7, pp. 757–760, Jul. 1997.
[13] G. Mathew, Y. X. Lee, and V. Krachkovsky, “A novel threshold
technique for minimizing error propagation in MDFE read channel,”
in IEEE Global Telecommunications Conference, vol. 6, Aug.
1998, pp. 3362–3367.
[14] M. Reuter, J. Allen, J. Zeidler, and R. North, “Mitigating error propagation
effects in a decision feedback equalizer,”IEEE Transactions
on Communications, vol. 49, no. 11, pp. 2028–2041, Nov. 2001.
[15] C. Cheng and D. Chang, “Improved time-domain channel tracking
algorithms for mobile OFDM applications,”in IEEE 4th VTS Asia
Pacific Wireless Communication Symposium(APWCS 2007), Aug.
2007.
[16] T. L. Hong, Design of OFDM Transceiver for WLAN in the Time-
Varying Channel based on IEEE 802.11a. Master Thesis, Department
of Communication Engineering, National Central University,
Jhongli Taiwan,July, 2006.
[17] W. C. Jakes, Microwave Mobile Communications. New York: John
Wiley, 1974.

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