由於微投影技術在行動裝置市場的應用潛力，因此若能夠利用微投影光源來實現可見光通訊技術，則行動裝置上的微投影架構將不僅能夠進行微投影應用亦將能提供短距離之可見光資訊傳輸，不僅不會增加生產成本更將為行動裝置帶來更大的附加價值。
有別於室內照明用之白光LED普遍使用藍光LED及螢光粉來產生白光，目前應用於微投影架構之光源主要仍以RGB-based LED為主，因此本論文將研究探討以RGB-based LED為主要光源之短距離可見光通訊系統之實現。研究首先利用積分球針對實驗用之光源進行光學特性量測，來瞭解其發光效率。由於LED本身具備的調變頻寬決定了系統整體之資料傳輸率，因此在固定350 mA偏壓的條件下，本研究透過點頻測試法來進行LED頻寬之基本量測，續而透過一階RC後置等化器之設計來進行LED頻寬之改善。實驗結果顯示紅光LED之頻寬可由原先之6 MHz提升至66.5 MHz、綠光LED之頻寬可由原先之15.5 MHz提升至56MHz、而藍光LED之頻寬則可由原先之13.5 MHz提升至66 MHz，整體系統總頻寬由原先之35 MHz提升至188.5 MHz (超過五倍之原始頻寬)
在有效提升系統總頻寬後。本論文嘗試透過數位調變技術(NRZ-OOK與4-PAM)搭配後置等化器，來進行資料傳輸率之研究，並透過示波器之量測結果來估算位元錯誤率(BER)。量測結果顯示透過後置等化器加上使用NRZ-OOK之調變技術，在滿足BER為10-3時，系統整體之資料傳輸率將可由原先之150 Mb/s提升至525 Mb/s (約為原始資料率之3.5倍)；而若透過後置等化器加上使用4-PAM之調變技術，在滿足BER為10-3時，系統整體之資料傳輸率將可由原先之142.5 Mb/s提升至480 Mb/s (約為原始資料率之3.3倍)。雖然4-PAM調變技術具有較高之頻譜效益，但由於接收訊號還原時易因系統元件特性及雜訊之影響促使得在示波器上判讀不易，所以總傳輸率略低於NRZ-OOK，而NRZ-OOK由於訊號還原容易，加上不需使用多重數位訊號處理技術，所以明顯優於4-PAM調變技術。

Due to the high potential of using micro-projection technology for porta-ble device application, it is expected that high-speed visible communication technologies based on the light sources of micro-projector will be integrated into the architecture of micro-projection. In distinguished with the conventional white light LED which is composed of blue LED and phosphor, this research intends to implement an experimental short-range high-speed visible light communication (VLC) system based on the use of RGB-based LED which has widely employed as the light source in micro-projector.
In order to understand the luminous efficiency of RGB-based LED, this research started with the optical characteristic measurement by using integrat-ing sphere. Since the data transmission rate of a VLC system is majority domi-nated by its modulation bandwidth, the fundamental bandwidth of RGB-based LED was measured under a fixed driving current of 350 mA. A first-order RC post-equalization approach was thereafter investigated to improve its modula-tion bandwidth. From the measurement results, it is clear that the modulation bandwidth of Red, Green and Blue LED with the use of a designed 1st order RC post-equalizer has improved from 6 MHz to 66.5 MHz, 15.5 MHz to 56 MHz, and 13.5 MHz to 66 MHz respectively. The total system modulation bandwidth with the use of a designed 1st order RC post-equalizer has improved from original 35 MHz to 188.5 MHz.
Finally, digital modulation techniques (NRZ-OOK and 4-PAM) with the use of a designed 1st order RC post-equalizer were employed to explore the data transmission rate. The system BERs were evaluated through the eye-diagram measured from Oscilloscope. The results shown that with the use of a designed 1st order RC post-equalizer, an aggregative data transmission rate over 500 Mb/s at a BER of 10-3 can be achieved by using NRZ-OOK modulation technique without any offline signal processing which is slightly better than 4-PAM, a more complex offline signal processing is required in order to recovery the received signal at a satisfied BER.

[1] “Visible Light Communications Consortium.” Internet: www.vlcc.net/ , 2008 [Mar. 15, 2014].
[2] “AV&IT Technology Standardization: Visible Light Communications.” Internet: www.jeita.or.jp/cgi-bin/standard_e/list.cgi?cateid=1&subcateid = 50, 2007 [Mar. 15, 2014].
[3] IEEE Standard for Local and Metropolitan Area Networks – Part 15.7: Short-Range Wireless Optical Communication Using Visible Light, IEEE Standard 802.15.7-2011, pp 1-309, 2011
[4] “Smart Lighting ERC.” Internet: smartlighting.rpi.edu, 2012. [Mar. 15, 2014]
[5] “Omega project consortium.” Internet: www.ict-omega.eu, 2008 [Mar. 15, 2014].
[6] “勤上與清華大學合作LED無線光通信研發” Internet: www.ledinside.com.tw/news/20130515-26331.html, Mar. 15, 2013 [Mar. 15, 2014].
[7] “Wireless data from every light bulb.” Internet: www.ted.com/talks/ har-ald_haas_wireless_data_from_every_light_bulb, Aug. 2011 [Mar. 15, 2014].
[8] “pureLiFi™.” Internet: purelifi.com, 2014 [Mar. 15, 2014].
[9] Nikola Serafimovski, “pureLiFi announces Li-Fi breakthrough.” Internet: purelifi.com/purelifi-announces-li-fi-breakthrough, Mar. 20, 2014 [Mar. 25, 2014].
[10] K.-D. Langer and J. Grubor, “Recent developments in optical wireless communications using Infrared and visible light,” in Proc. ICTON, 2007, pp. 146-151.
[11] 簡名仁， “基於微投影架構之300 Mb/s 高速LED可見光通訊”，國立台灣科技大學碩士論文，2014年6月。
[12] 陳金鑫，黃孝文，夢幻顯示器OLED材料與元件，五南圖書出版社，2012年2月。
[13] E.H. Stupp and M. S. Brennesholtz. Projection Display. England: Wiley, 1999.
[14] Texas Instruments. “DLP technology.” Internet: www.dlp.com/technology Mar. 24, 2014 [Mar. 15, 2014].
[15] I. Underwood, “A review of microdisplay technology,” in Proc. EID, 2000, pp. 1-6.
[16] P. A. Haigh, Z. Ghassemlooy, I. Papakonstantinou, and H. L. Minh, “2.7 Mb/s with a 93-kHz white organic light emitting diode and real time ANN equalizer,” IEEE Photonics Technol. Lett., vol. 25, no. 17, pp. 1041-1135, Sep. 1, 2013.
[17] P. A. Haigh, Z. Ghassemlooy, I. Papakonstantinou, F. Arca, S.F. Tedde, O. Hayden, and E. Leitgeb, “A 1-Mb/s visible light communications link with low bandwidth organic components,” IEEE Photonics Technol. Lett., VOL. 26, NO. 13, pp. 1295-1298, Jul. 1, 2014.
[18] H. Chun, C.-J. Chiang, A. Monkman, and D. O’brien, “A study of illumi-nation and communication using organic light emitting diodes,” IEEE J. Lightw. Technol., vol. 31, no. 22, pp. 3511-3517, Nov. 15, 2013.
[19] E. F. Schubert, Light-Emitting Diodes, 2nd ed., Cambridge: Cambridge University Press, 2006.
[20] 王書任，林仁鈞， “讓LED發光的功臣─螢光粉”，科學發展，第435期，第22-27頁，2009年3月。
[21] S. Muthu, F. J. Schuurmans, and M. D. Pashley, “Red, green and blue LED based white light generation: issues and control,” in Proc. IEEE IAC, 2002, pp. 327-333.
[22] 黃建歷，“高功率白光LED照明之光學設計”，國立台灣科技大學碩士論文，2009年7月。
[23] “Broadband Coaxial Bias Tees,” 1st ed., Picosecond Pulse Labs, Boulder, CA, 2000.
[24] J. M. Kahn and J. R. Barry, “Wireless Infrared communications,” PROC. IEEE, vol. 85, no. 2, pp.265-298, Feb. 1997.
[25] D. Wu, Z. Ghassemloy, H. L. Minh, S. Rajbhandari, and Y. S. Kavian, “Power distribution and Q-factor analysis of diffuse cellular indoor visi-ble light communication systems,” in Proc. NOC, 2012, pp. 28-31.
[26] L. Zeng, D. C. O’brien, H. L. Minh, G. E. Faulkner, K. Lee, D. Jung, Y. Oh, and E. T. Won, “High data rate multiple input multiple output (MIMO) optical wireless communications using white LED lighting,” IEEE J. Se-lect. Areas Commun., vol. 27, no. 9, pp. 1654-1662, Dec. 1, 2009.
[27] R. M. Gagliardi and S. Karp, Optical Communications, 2nd ed. New York: John Wiley & Sons Inc., 1995.
[28] Z. Ghassemlooy, W. Popoola, and S. Rajbhandrai. Optical Wireless Communications: System and Channel Moderlling with MATLAB®, New York: CRC Press, 2012.
[29] “GaAsP photodiodes: Visible light sensors.” Internet: www.hamamatsu. com/jp/en/4196.html [Mar. 17, 2014].
[30] S.B. Alexander. Optical Communication Receiver Design, Washington: SPIE Optical Engineering Press, 1997.
[31] J.C. Palais. Fiber Optic Communications, 5th ed. New Jersey: Pear-son/Prentice Hall, 2005.
[32] J.M. Senior. Optical Fiber Communications Principles and Practice, 3rd ed. Essex: Person Education Limited, 2009
[33] T. Kishi, H. Tanaka, Y. Umeda, and O. Takyu, “A high-speed LED driver that sweeps out the remaining carriers for visible light communications,” IEEE J. Lightw. Technol., vol. 32, no. 2, pp. 239-249, Jan. 15, 2014.
[34] J. Grubor, O. C. G. Jamett, J. W. Walewski, S. Randel, and K.-D. Lang-er :High-speed wireless indoor communication via visible light, in ITG Fachbericht 198, pp. 203-208, Berlin und Offenbach: VDE-Verlag, 2007.
[35] H. L. Minh, D. O’brien, G. Faulkner, and L. Zeng, “80 Mbit/s visible light communication using pre- equalized white LED,” in Proc. ECOC, 2008, pp. 1-2.
[36] H. L. Minh, D. O’Brien, G. Faulkner, L. Zeng, K. Lee, D. Jung, Y. Oh, and E. T. Won, “100-Mbit/s NRZ visible light communication using a poste-qualized white LED,” IEEE Photonics Technol. Lett., vol. 21, no. 15, pp. 1063-1065, Aug. 1, 2009.
[37] H. Li, X. Chen, B. Huang, D. Tang, and H. Chen, “High bandwidth visible light communications based on a post-equalization circuit,” IEEE Pho-tonics Technol. Lett., vol. 26, no. 2, pp. 119-122, Jan. 15, 2014.
[38] Y. S. Cho, J. Kim, W. Y. Yang, and C. G. Kang. MIMO-OFDM Wireless Communications with MATLAB. New Jersey: IEEE Press: J. Wiley & Sons, 2010.
[39] J. Vucic, C. Kottke, S. Nerreter, K.-D. Langer, and J. W. Walewski, “513Mbit/s visible light communications links based on DMT-modulation of a white LED,” IEEE J. Lightw. Technol., vol. 28, no. 24, pp. 3512-3518, Dec. 15, 2014.
[40] A. H. Azhar, T.-A. Tran, and D. O’Brien, “A Gigabit/s indoor wireless transmission using MIMO-OFDM visible-light communications,” IEEE Photonics Technol. Lett., vol. 25, no. 2, pp. 119-122, Jan. 15, 2013.
[41] J. Vucic, C. Kottke, K. Habel, and K.-D. Langer, “803 Mbit/s visible light WDM link based on DMT modulation of a single RGB LED luminary,” in Proc. OFC, 2011, pp. 1-3.
[42] G. Cossu, A. M. Khalid, P. Choudhury, R. Corsini, and E. Ciaramella, “3.4 Gbit/s visible optical wireless transmission based on RGB LED,” Opt. Express, vol. 20, no. 26, pp. B501-B506, Dec. 2012.
[43] Y. Wang, and N. Chi, “A high-speed bi-directional visible light communi-cation system based on RGB-LED,” China Commun., vol. 11, no. 3, pp. 40-44, Mar. 2014
[44] G. Cossu, A. M. Khalid, P. Choudhury, E. Corsini, and E. Ciaramella, “Long distance indoor high speed visible light communication system based on RGB LEDs,” in Proc. ACP, 2012, pp. 1-3.
[45] Y. Wang, N. Chi, Y. Wang, R. Li, X. Huang, C. Yang, and Z. Zhang, “High-speed quasi-balanced detection OFDM in visible light communication,” Opt. Express, vol. 21, no. 23, pp. 27558-27564, Nov. 2013.
[46] J. Y. Sun, C. W. Chow, and C. H. Yeh, “Dimming-discrete-multi-tone (DMT) for simultaneous color control and high speed visible light com-munication,” Opt. Express, vol. 22, no. 7, pp. 7538-7543, Mar. 2014.
[47] F. M. Wu, C. T. Lin, C. C. Wei, C. W. Chen, Z. Y. Chen, H. T. Huang, and S. Chi “Performance comparison of OFDM signal and CAP signal over high capacity RGB-LED based WDM visible light communication,” IEEE Photon. J., vol. 5, no. 4, Aug. 2013.
[48] Y. Wang, L. Tao, Y. Wang, and N. Chi, “High speed WDM VLC system based on multi-band CAP64 with weighted pre-equalization and modified CMMA based post-equalization,” IEEE Commun. Lett., vol. PP, no. 99, Aug. 2014.
[49] Y. Wang, R. Li, Y. Wang, and Z. Zhang, “3.25-Gbps visible light commu-nication system based on single carrier frequency domain equalization utilizing an RGB LED,” in Proc. OFC, 2014.
[50] N. Chi, Y. Wang, Y. Wang, X. Huang, and X. Lu, “Ultra-high-speed single red-green-blue light-emitting diode-based visible light communication system utilizing advanced modulation formats,” Chinese Opt. Lett., vol. 12, no. 1, pp. 010605(1)- 010605(4), Jan. 2014.
[51] Y. Wang, X. Huang, J. Zhang, Y. Wang, and N. Chi, “Enhanced perfor-mance of visible light communication employing 512-QAM N-SC-FDE and DD-LMS,” Opt. Express, vol. 22, no. 13, pp. 15328-15334, Jun. 2014.
[52] S. Haykin. Communications Systems, 4th ed., New York: John Wiley & Sons, Inc, 2001.
[53] R. Otte. Low Power Wireless Optical Transmission: Systems for Commu-nications, Telemetry and control, Delft University Press, The Netherlands, 1998.
[54] J. G. Proakins and M. Salehi. Digital Communications, 5th ed., New York: McGraw-Hill, 2008.
[55] K. Szczerba, M. Karlsson, and P. Andrekson, “32.5 Gbps 8-PAM trans-mission over 100 m of MMF using an 850 nm VCSEL,” in Proc. ECOC, 2013, pp. 1-3.
[56] D. Derickson. Fiber Optics test and Measurement. New Jersey: Prentice Hall OTR, 1998.
[57] I. Sphake, H. Takara, and S. Kawanishi, “Simple measurement of eye dia-gram and BER using high-speed asynchronous sampling,” IEEE J. Lightw. Technol., vol. 22, no. 5, pp. 1296-1302, May 18, 2004.
[58] 陳偉婷， “兼具照明之LED可見光通訊之設計硏製” ，國立台灣科技大學碩士論文，2012年7月。
[59] LUXEON® Z: Color and White LED Portfolio, Philips Ltd., Amsterdam, Netherlands,2012.
[60] PDA-10A Si Amplified Fixed Detector User Guide, Thorlabs Inc., Newton, NJ, 2014.
[61] 朱錫仁，電路測試技術與儀器，台北市: 儒林圖書有限公司，1992。
[62] J. Tuo, H. Shams, and B. Corbett, “Visible light communication by using commercial phosphor based white LEDs,” in Proc. ISSC, 2012, pp. 1-4.
[63] T. Y. Elganimi, “Performance Comparison between OOK, PPM and PAM Modulation Schemes for Free Space Optical (FSO) Communication Sys-tems: Analytical Study,” INT J. COMPUT APPL., vol. 79, no. 11, pp. 22-27, Oct. 2013.
[64] Anatomy of an Eye Diagram, Tektronix Ltd., Beaverton, Ore., 2013.