本論文針對OFDM系統之時序同步問題，提出Constant Pilot Padding Method(CPPM)。CPPM方法為在傳送端頻域上，有規則的安插調變資料，於時域產生具備重複特性的時域符元，作為時序估測使用之Preamble符元，並以頻域上填補的Pilot符元，提供通道估測能力，同時可於Preamble符元內傳送部份資料。另分析頻域上填補的Pilot值，對於時序估測效能及時域符元的PAPR值影響。最後以LOS及NLOS環境的室外實測通道，使用建議的Pilot值，分別檢測CPPM方法的時序同步及通道估測效能。模擬結果顯示，CPPM時序估測誤差，明顯小於S&C方法，且有與Park’s方法相當的估測效能，CPPM方法可同時進行通道估測，Park’s方法則不具此功能。

In this paper, we propose a Constant Pilot Padding Method (CPPM) that can perform both the timing synchronization and channel estimation in the Orthogonal Frequency Division Multiplexing (OFDM) systems. The CPPM method exploits the repetitive structure of the preamble that can be generated by inserting the constant pilots in the frequency domain to execute the timing synchronization. In addition, the CPPM method has the ability of channel estimation with these padding pilots.
Compared with the conventional synchronization methods, such as the S&C method and the Park’s method, the preamble of the CPPM provides not only timing synchronization but also data transmission. Simulation results show that the proposed timing estimation performance is more precise and robust than the S&C method and the Park’s method.

目錄
摘要 I
Abstract II
目錄 III
圖目錄 V
表目錄 IX
第一章 導論 1
1.1背景簡介 1
1.2論文大綱 2
第二章 Proposed OFDM System於時序估測及通道估測之效能 3
2.1 三種時序估測法及其效能分析 5
2.1.1 S&C Method時序估測法[1] 6
2.1.2 Minn’s Method時序估測法[2] 11
2.1.3 Park’s Method時序估測法[3] 13
2.1.4模擬結果及比較 15
2.2 Proposed Symbol Timing Estimation 19
2.2.1 Constant Pilot Padding Method (CPPM) 19
2.2.2於不同調變模式之時域符元格式 21
2.2.3 Proposed時序估測法模擬及比較 33
2.3 通道估測法與效能分析 46
2.3.1Proposed通道估測法 47
2.3.2於Rayleigh Fading Channel之模擬結果 49
第三章 Padding Value對PAPR及時序估測效能之影響 54
3.1 Padding Value對PAPR值之影響 54
3.2 Padding Value對時序估測效能的影響 56
3.2.1於QPSK調變，改變P值檢視時序估測效能 57
3.2.2於16QAM調變，改變P值檢視時序估測效能 62
3.2.3於BPSK調變，改變P值檢視時序估測效能 64
第四章 於室外量測通道之效能分析 70
4.1室外量測通道介紹 70
4.2 Proposed時序估測法於室外量測通道之模擬 75
4.2.1以QPSK調變於室外量測通道之模擬結果 76
4.3通道估測法於室外實測通道之模擬 79
4.3.1於室外實測通道之模擬結果 79
第五章 結論與未來工作 84
5.1結論 84
5.2未來探研方向 85
參考文獻 87

[1]T.M. Schmidl and D.C. Cox, “Robust frequency and timing
synchronization for OFDM,” IEEE Trans. Commun., vol.45,
no.12, pp.1613-1621, Dec. 1997.
[2]H. Minn, M. Zeng, and V.K. Bhargava, “On timing offset
estimation for OFDM Systems,” IEEE Commun. Lett.,
vol.4, no.7,pp.242-244 ,July 2000.
[3]Byungjoon Park, Hyunsoo Cheon, Changeon Kang, Daesik
Hong, “A novel timing estimation method for OFDM
systems,” Communications Letters ,IEEE Volume 7, Issue
5, May 2003 Page(s):239-241
[4]Garcia, M.J.F.-G.; Paez-Borrallo, J.M., ”Tracking of
time misalignments for OFDM systems in multipath fading
channels,” Consumer Electronics, IEEE Transactions on
Volume 48, Issue 4, Nov 2002 Page(s):982-989
[5]Chin-Liang Wang; Ming-Hsuan Chiang; Hung-Chin Wang, ”A
new synchronization scheme for OFDM systems,” Vehicular
Technology Conference, 2004. VTC 2004-Spring. 2004 IEEE
59th Volume 2, 17-19 May 2004 Page(s):1100-1104 Vol.2
[6]J. J. van de Beek, M. Sandell, and P. O. Borjesson, “ML
estimation of time and frequency offset in OFDM
systems”; Signal Processing, IEEE Transactions on
Volume 45,Issue 7,July 1997 Page(s):1800-1805
[7]Cheng-Ying Yang; Gwo-Ruey Lee; Wen-Hui Kuan; Jyh-Horng
Wen, “Symbol synchronization at the BPSK-OFDM
receiver,” Mobile WiMAX Symposium, 2007. IEEE 25-29
March 2007 Page(s):12-16
[8]Hewei Yu, “A Novel Timing Estimation Method Based on
Symmetrical & Conjugate Prefix in OFDM System,”
Wireless Communications, Networking and Mobile
Computing, 2006. WiCOM 2006.International Conference on
　　22-24 Sept. 2006 Page(s):1-4
[9]Young-Hwan YOU, Eu-Suk SHIM, and Hyoung-Kyu SONG, ”A
　　Frame Detector for Zero-Padded OFDM Systems”, IEICE
　　Trans B: Communications on Volume E89-B,NO.3, March
　　2006, Page(s):963-965
[10]Le Van Ninh; Trinh Anh Vu; Huu Tue Huynh; Fortier,
　　P., “New Cyclic Prefix Based Symbol Timing and Carrier
　　Synchronization for OFDM,” Communications, 2006 23rd
　　Biennial Symposium on May 29-June 1, 2006 Page(s):198-
　　203
[11]Hee Wook Kim; Kunseok Kang; Do-Seob Ahn, “Efficient
　　Time and Frequency Synchronization for OFDM based
　　Wireless Indoor Communication over Rician Fading
　　Channel,” Consumer Electronics, 2006. ISCE '06. 2006
　　IEEE Tenth International Symposium on 2006 Page(s):1-5
[12]Feng Yang; Kwok H. Li; Kah C. Teh; “Adaptive LMS-like
　　algorithm for carrier frequency offset estimation in
　　OFDM systems,” Signal Processing and Its Applications,
　　2005. Proceedings of the Eighth International Symposium
　　on Volume 1, August 28-31, 2005 Page(s):131-134
[13]Liu, H.; Tureli, U., “A high-efficiency carrier
　　estimator for OFDM communications,” Communications
　　Letters,IEEE Volume 2, Issue 4, April 1998 Page(s):104-
　　106
[14]Qi Cheng; “Choice of Root in Root-MUSIC for OFDM
　　Carrier Frequency Offset Estimation,” Communications,
　　2005 Asia-Pacific Conference on 03-05 Oct. 2005 Page
　　(s):534-536
[15]Biao Chen; Hao Wang; ”Blind OFDM carrier frequency
　　offset estimation via oversampling” Signals, Systems
　　and Computers, 2001. Conference Record of the Thirty-
　　Fifth Asilomar Conference on Volume 2, 4-7 Nov. 2001
　　Page(s):1465-1469 vol.2
[16]Han-wen Luo; Yun Wu; Chong-Guang Yan; Ming Ding, “Fast
　　Frequency Offset Estimation Method for OFDM,” Wireless
　　Communications, Networking and Mobile Computing, 2006.
　　WiCOM 2006.International Conference on 22-24 Sept. 2006
　　Page(s):1-4
[17]En Zhou, Xing Zhang, Hui Zhao, Wenbo
Wang, “Synchronization Algorithms for MIMO OFDM
　　Systems”, Wireless Communications and Networking
　　Conference, 2005 IEEE Volume 1, 13-17 March 2005 Page
　　(s):18-22 vol. 1
[18]S. Coleri; M. Ergen; A. Puri and A. Bahai, “Channel
　　Estimation Techniques Based on Pilot Arrangement in
　　OFDM Systems,” IEEE Trans. on Broadcasting, vol.48,
　　no.3, pp.223-229, 2002.
[19]Jihyung Kim; Jeongho Park; Daesik Hong, “Performance
analysis of channel estimation in OFDM systems,”
Signal Processing Letters, IEEE Volume 12, Issue 1,
Jan. 2005 Page(s):60-62
[20]Jeongho Park; Jihyung Kim; Myonghee Park; Kyunbyoung
Ko; Changeon Kang; Daesik Hong, “Performance analysis
of channel estimation for OFDM systems with residual
timing offset,” Wireless Communications, IEEE
Transactions on Volume 5, Issue 7, July 2006 Page
(s):1622-1625
[21]Xianbin Wang; Yiyan Wu; Kechu Yi; Bin Tian; Chouinard,
J.-Y., “A fast synchronization technique for DVB-H
receiver using in-band pilots and cyclic prefix,”
Consumer Electronics, 2006. ICCE '06. 2006 Digest of
Technical Papers. International Conference on 7-11 Jan.
2006 Page(s):407-408
[22]Ludwig Schwoerer, “Fast Pilot Synchronization Schemes
for DVB-H,” Proceedings of the 4th International Multi-
Conference Wireless and Optical Communications, July 8-
10, 2004, pp.420-424
[23]Tang, S.; Gong, K.; Song, J.; Pan, C.; Yang, Z.,
Intercarrier Interference Cancellation with Frequency
Diversity for OFDM Systems,” Broadcasting, IEEE
Transactions on Volume 53, Issue 1, Part 1, March 2007
Page(s):132- 137
[24]Y. Zhao and S. G. Haggman, “Intercarrier interference
self-cancellation scheme for OFDM mobile communciation
systems,” Communications, IEEE Transactions on Volume
49, Issue 7, July 2001 Page(s):1185-1191
[25]K. Sathananthan, R. M. A. P. Rajatheva, and S. B.
Slimane, “Cancellation technique to reduce
intercarrier interference in OFDM,” Electronics
Letters Volume 36, Issue 25, 7 Dec. 2000 Page(s):2078-
2079
[26]Y. Fu, S. G. Kang, and C. C. Ko, “A new scheme for
PAPR reduction in OFDM systems with ICI self-
cancellation,” Vehicular Technology Conference, 2002.
Proceedings. VTC 2002-Fall. 2002 IEEE 56th Volume 3, 24-
28 Sept. 2002 Page(s):1418-1421 vol.3
[27]K. Sathananthan, C. R. N. Athaudage, and B. Qiu, “A
novel ICI cancellation scheme to reduce both frequency
offset and IQ imbalance effects in OFDM,” Computers
and Communications, 2004. Proceedings. ISCC 2004. Ninth
International Symposium on Volume 2,28 June-1 July 2004
Page(s):708-713 Vol.2
[28]Li Zhao; Ping Zhang, “ A New ICI Self-Cancellation
Scheme Based on Repeated Symbol in OFDM
Systems,”Communications, Circuits and Systems
Proceedings, 2006 International Conference on Volume
2,25-28 June 2006 Page(s):1216-1220
[29]Richard van Nee, Ramjee Prasad, OFDM for Wireless
Multimedia Communications, Artech House, 2000.
[30]John Terry and Juha Heiskala, OFDM Wireless Lans: A
Theoretical and Practical Guide, Sams, 2002
[31]T.S. Rappaport, Wireless Communications: Principles and
Practice, Prentice Hall PTR,1996
[32]Hiroshi Harada, Ramjee Prasad, Simulation and Software
Radio for Mobile Communications, Artech House, 2002