可見光通訊(Visible Light Communication, VLC)是一種利用可見光調變的通訊技術，所擁有的特性與一般傳輸大不相同，主要來自於傳輸介質是利用可見光而非一般的無線電，可見光相較於無線電擁有較高的安全性，可結合一般照明使用於廣播(Broadcast)或特定場合的單向傳輸，強度通常跟一般照明一樣，由於光線是人眼可見，若光束過強也可經由肉眼觀察出，因此相較之下，可見光通訊具有較高的安全性。可見光還具有其他優點，在後續章節會繼續探討。而本論文探討重點在解決可見光通訊系統中之通道衰減以及抵抗雜訊干擾提升傳輸效率。
本論文針對VLC系統設計一套利用不對稱剪裁正交分頻多工調變之規格，其規格是從IEEE 802.11a中改制而成，並利用此規格設計接收機用於VLC系統之中。此接收機包含時頻域轉換、同步和等化等設計。其中時頻域轉換使用較一般正交分頻多工不同於使用哈特利轉換器，其實數運算核心十分適合VLC系統，可達到節省硬體提升效能目的。等化包含通道估測和補償的資料回復設計。同步包含取樣時脈偏移估測補償和符碼區間偵測的設計。本論文使用Matlab與C平台建立模擬系統。電路部分使用Verilog HDL描述，並使用TSMC-90nm製程來實現所設計之電路，以驗證電路設計。

Visible light communication is a communication technology, have very different characteristics with general communication technology because of the transmission media. Visible light communication has a higher security compared to radio communication. VLC can be combined with general lighting for use in a particular situation or a one-way broadcast transmission. The intensity of VLC is generally the same as lighting. If the beam is too strong can also be observed cause the transmission media is visible. We will continue to explore in the following sections about other advantages of VLC. The focus of this paper examines the visible light communication system in addressing the channel attenuation and resistance to noise interference to enhance the transmission efficiency.
In this paper, design a system for ACO-OFDM (Asymmetrically Clipped Optical OFDM). The specifications from the IEEE 802.11a in restructuring , and using this design specification for the system among VLC. The receiver comprises time and frequency domain conversion, synchronization, and so on. The conversion between time and frequency using Hartley converter instead of general Fourier converter in OFDM, the real arithmetic core of DHT is suitable for VLC. It achieve savings of hardware and enhance the effectiveness. Equalization includes channel estimation and compensation. Synchronization includes sampling clock offset estimation and compensation also have boundary detection.

[1] 陳右昀, “應用於PLC系統之AGC-CR通道等化技術,” 中央大學, 電機工程學系碩士論文, 2008.
[2] P. B. Denyer and D. Renshaw, "VLSI Signal Processing; A Bit-Serial Approach," Addison-Wesley Longman Publishing Co., Boston, Ma, USA,1985.
[3] Kwonhyung Lee and Hyuncheol Park, "Channel Model and Modulation Schemes for Visible Light Communications," IEEE Circuits and Systems (MWSCAS), 2011 IEEE 54th International Midwest Symposium, 7-10 Aug. 2011.
[4] Xie Zhang, Kaiyun Cui, Minyu Yao, Hongming Zhang, Zhengyuan Xu, "Experimental Characterization of Indoor Visible Light Communication Channels," Communication Systems, Networks & Digital Signal Processing (CSNDSP),56 Poznan, 2012.
[5] Toshihiko Komine, Student Member, IEEE, and Masao Nakagawa, Member, IEEE "Fundamental Analysis for Visible-Light Communication System using LED Lights," IEEE Transactions on Consumer Electronics, Vol. 50, No. 1, FEBRUARY 2004.
[6] Hany Elgala, Student Member, IEEE, Raed Mesleh, Member, IEEE and Harald Haas, Member, IEEE, "Indoor Broadcasting via White LEDs and OFDM," Contributed Paper ,Manuscript received, July 14, 2009
[7] Adam C. Erickson, Member, IEEE, and Barry S. Fagin, Member, IEEE, "Calculating the FHT in Hardware," IEEE TRANSACTIONS ON SIGNAL PROCESSING, VOL. 40. NO. 6. JUNE 1992.
[8] Jinlong ZHANG, "Modulation Analysis for Outdoors Applications Of Optical Wireless Communications," Research & Standardization, Radio Access Systems, Nolua Networks Oy PL 372, 00045, Nokia Group, Finland, 2000.
[9] Ghafour Amouzad Mahdiraji and Edmond Zahedi, "Comparison of Selected Digital Modulation Schemes (OOK, PPM and DPIM) for Wireless Optical Communications," Department of Electrical, Electronic \& System Engineering, Faculty of Engineering, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia,Student Conference on Research and Development (SCOReD 2006), Shah Alam, Selangor, MALAYSIA, 27-28 June, 2006.
[10] Jean Armstrong, Senior Member, IEEE, "OFDM for Optical Communications," OURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 27, NO. 3, FEBRUARY 1, 2009.
[11] 蕭建堯, "應用於可見光通訊之OFDM接收機設計與實現," 中央大學, 電機工程學系碩士論文, 2014.
[12] J. Armstrong and A.J. Lowery, "Power efficient optical OFDM," ELECTRONICS LETTERS, Vol. 42, No. 6, 16th, March, 2006.
[13] Wei Xu, Member, IEEE, Man Wu, Hua Zhang, Member, IEEE Xiaohu You, Fellow, IEEE Chunming Zhao, Member, IEEE, "ACO-OFDM-Specified Recoverable Upper Clipping With Efficient Detection for Optical Wireless Communications,"IEEE Photonics Journal, Volume 6, Number 5, October 2014.
[14] Lars Erup, Member, IEEE, Floyd M. Gardner, Fellow, IEEE, and Robert A. Harris, Member, IEEE, "Interpolation in Digital Modems-Part II: Implementation and Performance," IEEE TRANSACTIONS ON COMMUNICATIONS, VOL. 41, NO. 6, JUNE 1993.
[15] Thierry Pollet and Miguel Peeters, Alcatel, "Synchronization with DMT Modulation," IEEE Communications Magazine April 1999.
[16] Michael Speth, Stefan A. Fechtel, Gunnar Fock, and Heinrich Meyr, "Optimum Receiver Design for Wireless Broad-Band Systems Using OFDM—Part I," IEEE Transactions on Communications, Vol.47, no. 11, November 1999.
[17] Svilen Dimitrov and Harald Haas, "On the Clipping Noise in an ACO-OFDM Optical Wireless Communication System," Institute for Digital Communications, Joint Research Institute for Signal and Image Processing, 2010.
[18] Eyal Katz, Amir Laufer, Yeheskel Bar-Ness, "A New Improved-Performance Decoding Technique for Asymmetrically-Clipped Optical-OFDM," The Center of Wireless Communications and Signal Processing Research, ECE, New Jersey Institute of Technology, Newark, USA, 2012.
[19] HENRIQUE S. MALVAR, "Fast Computation ofthe Discrete Cosine Transform and the Discrete Hartley Transform," IEEE Transactions on acoustics, Speech, and Signal Processing, Vol. ASSP-35, No.10 ,October 1987.
[20] Zoran CvetkoviC and Miodrag V. PopoviC, "New Fast Recursive Algorithms for the Computation of Discrete Cosine and Sine Transforms," Manuscript received December 14. 1990; revised June 25, 1991.
[21] Michela Svaluto Moreolo, Raül Muñoz, and Gabriel Junyent, "Novel Power Efficient Optical OFDM Based on Hartley Transform for Intensity-Modulated Direct-Detection Systems," JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 28, NO. 5, MARCH 1, 2010.