DVB-T系統所採用的核心技術是正交分頻多工（OFDM）。此技術運用了多載波間正交特性以達到高頻譜效益。並藉由前置循環字首（Cyclic prefix）來抵抗多重路徑干擾以及多載波之特性以達到消除符碼間干擾（ISI, Inter-symbol Interference）；在高速移動環境下，DVB-T訊號經過時變的通道，接收到的訊號會產生都普勒擴展(Doppler Spread)的現象，破壞子載波間的正交性並進一步引起載波間干擾(ICI)；而載波間干擾會隨著移動速度上升而越加嚴重，導致系統性能下降。為了克服高速移動所引起的載波間干擾(Inter-carrier Interference，ICI)，本論文將前人方法加以改良，介紹了一套適合高速移動接收的通道估測和載波間干擾消除。本論文參考DVB-T系統，並且進一步的修改使其更合適於高速移動下的環境。針對所有受到ICI干擾的訊號，我們利用以下步驟：首先通道估測、其次.反覆式ICI消去方法，最後反覆使用最大近似（Maximum Likelihood，ML）偵測法推導出的向量投影方式搜索，抑制載波間干擾、降低其錯誤率，提昇系統速度。

The core of DVB-T is OFDM system. By using multi-carriers and inserting cyclic prefix, this technology successfully eliminated the ISI effect and multi-path interference. In high-mobility environment, when DVB-T signals pass through the time-varying channel, the receive signals will have Doppler spread that can loss of sub-carrier orthogonality and cause the ICI. This ICI effect degrades the maximum allowed velocity of reception. To overcome the ICI which caused by the high-mobility, this thesis modifies other’s methods and introduces a method about the channel estimation and elimination of ICI which is suitable for high mobility reception. This thesis refers to the DVB-T standard, and further modifies it to suit in high-mobility environment. In high-mobility environment, the performance of wireless OFDM communication systems is degraded and limited by inter-carrier-interference (ICI) phenomenon. In this paper we proposed an algorithm based on maximum-likelihood criterion with improved performance in mitigation of ICI.

[1] ETSI EN 300 744, Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for digital terrestrial television, European Standard.
[2] Sinem Coleri, Mustafa Ergen, Anuj Puri, Ahmad Bahai, “Channel Estimation Techniques Based on Pilot Arrangement in OFDM Systems,” IEEE Transaction on Broadcasting, vol. 44, No.3, Sep. 2002
[3] A. Dowler and A. Nix, “Performance evaluation of channel estimation techniques in a multiple antenna OFDM system,” Proceedings of Vehicular Technology Conference, 2003. VTC 2003-Fall. 2003 IEEE 58th, vol. 2, pp. 1214-1218, 2003.
[4] B. Muquet, Z. Wang, G.B. Giannakis, M. de Courville, P. Duhamel, “Cyclic prefixing or zero padding for wireless multicarrier transmissions?”, IEEE Transactions on Communications, Volume 50, Page(s):2136 – 2148, Dec. 2002
[5] MOTIVATE report to the 36th DVB-T Meeting (2000-01) Using DVB-T standard to deliver broadcast Services to mobile receiver
[6] W. C. Jakes. “Microwave Mobile Communications” [M]. IEEE Press, Wiley Interscience, 1994.
[7] Y. Mostofi and D. Cox, “ICI mitigation for pilot-aided OFDM systems,” IEEE Transactions on Wireless Communications, vol. 4,no. 2, pp. 765-774, March 2005.
[8] Volker Fischer, Alexander Kurpiers and Dominik Karsunke,” ICI Reduction Method for OFDM Systems”, 8th International OFDM-Workshop 2003 (InOWo''03), Hamburg, Conference Proceedings.
[9] Tosato F, Bisaglia P. , “Simplified soft-output demapper for binary interleaved COFDM with application to HIPERLAN/2,” Proc ICC''02 [C]. 2002. pp. 664 -668.
[10] Soon Up Hwang, Jeong Hoon Lee, and Jongsoo Seo, “Low Complexity Iterative ICI Cancellation and Equalization for OFDM Systems Over Doubly Selective Channels,” IEEE Trans, Broadcasting, vol. 55, no. 1,March 2009.
[11] 陳書妤,” 高速移動環境下數位電視廣播系統之載波間干擾消除“,中央大學碩士論文。