在現在一個資訊爆炸的世代,人們無時無刻任何的地方都想要接受到訊息,但以舊有的無線通訊,是用電磁波來傳遞,在某些特殊場合就無法使用,以人體健康來看,無法在醫院使用,以資訊隱私來看,無法在高機密的場所使用,例如:軍事場所。取代電磁波無線通訊,我們發展可見光通訊,並且使用LED做我們的發光源,由於LED 現在全世界普以及可見光通訊高隱私、抗無線電磁波特性,這項技術已受到全球的關注。
而在這篇論文,我們使用目前商業用的LED (發光二極體)來做我們的發射源,因一般LED大多設計在照明使用,所以作為通訊使用時,其調變頻寬往往受限於幾十MHz以內,所以我們要在有限的頻寬中,使用高頻譜效率的訊號-無載波振幅相位調變,並利用預先補償的方式來增加有限頻寬，達到提升最大傳輸量的目的。另一方面,要如何拉長距離也是我們這篇論文的重要議題, 在接收端,我們使用高光電轉換效率的累增崩潰二極體來提升我們的傳輸距離和訊號品質,進一步的,我們探討兩個現象,第一是我們使用單一符元套入我們的無載波振幅相位調變訊號來,使訊號能經過頻域等化器和決策回授等化器,來解決可見光通訊通到頻響不平的現象;第二。是我們利用二對一多工分集技術,阿拉摩提-空間時間調變分別套用在無載波振幅相位調變和正交分頻多工來解決多通道干擾的問題。

In the information explosion era, people are desired to receive messages anywhere and anytime. The traditional wireless communication transmits messages via radiofrequency (RF) electromagnetic wave, but it cannot be used for some special cases. For instance, due to the health concerns raised about exposure to RF fields, it cannot be used in hospitals. In addition, considering low information security, it cannot be used in highly confidential situations, such as military applications. Alternative to RF wireless technologies, visible light communication (VLC) based on white light emitting diodes (LEDs) has attracted global attention, because of its advantages of worldwide availability, high security, and immunity to RF interference.
In the thesis, we use commercially available LEDs as our emission source. Because the LEDs adopted in VLC are designed for illumination, so the modulation bandwidth is generally limited to about tens MHz. Accordingly, we used the carrier-less amplitude and phase (CAP) modulation, which has high bandwidth efficiency, to transmit signals over the limited bandwidth, and the pre-compensation is also employed in our high-speed VLC experiments to improve signal performance. On the other hand, how to increase the transmitted distance is also one of our major topics. At the receiver, we use the high photoelectric conversion efficiency avalanche photo-detectors (APDs) to increase our transmission distance and to improve signal quality. We insert unique word (UW) into CAP signals, in order to apply both frequency domain equalization (FDE) and decision feedback equalization (DFE) to overcome the uneven frequency response of the VLC channel. Moreover, 2×1 multiple-input-single-output (MISO) VLC system is also experimentally demonstrated, and Alamouti space-time block coding (STBC) is employed to CAP or orthogonal frequency division multiplexing (OFDM) signals to deal with the problem of multipath interference.

Acknowledgement………………………………………………………….i
中文摘要………………………………………………………………..…..ii
Abstract.………………………………………………………………...…iii
Contents………………………………………………………………….…v
List of Figure……………………………………………………………....vii
List of Table………………………………………………………….……..x
Chapter I. Introduction………………………………….......................1
1.1 Background……………………………………...........................1
1.2 Motivation………………………….……….............................…4
1.3 Objective and Problem Statement…………........................….5
Chapter II. VLC Principle and DSP Technology……...............…...…6
2.1 Preface……………………………………....…...........................6
2.2 Principle of operation…………………..….............................…7
2.3 Carrier-less Amplitude and Phase Modulation........................10
2.3.1 Principle…………………………..…..………...........................10
2.3.2 Concept of Decision Feedback Equalizer…...........................13
2.3.3 Concept of Pre-compensation………………........................…14
2.4 Orthogonal Frequency Division Multiplexing...........................16
2.4.1 Principle…………………………..………...…..........................16
2.4.2 Concept of Bit Loading……………..……..…..........................19
2.5 Frequency domain equalizer for CAP……..........................…22
2.5.1 Principle…………………………..…...…...…..........................22
2.5.2 Concept of Unique word……………………..........................…23
2.6 Alamouti Space Time Block Coding…...…….........................24
Chapter III. Experimental Demonstration of 1X1 SISO
Employ the CAP with UW or CP in frequency domain equalizer......29
3.1 Preface………………………………….........................….......29
3.2 Experimental Setup…...………………..….............................29
3.3 Experimental Result and Discussion……......................….…31
3.4 Experimental Result with Pre-compensation and Discussion..34
3.5 Summary……………………………………..........................…37
Chapter IV.Experimental Demonstration of 2X1 MISO System
Employing STBC with CAP modulation.........................................38
4.1 Preface………………………………….…...............................38
4.2 Experimental Setup…...………………..….............................38
4.3 Experimental Result and Discussion……….…......................39
4.4 Summary………………………………………..........................45
Chapter V. Experimental Demonstration of 2X1 MISO System
Employing STBC with OFDM modulation …………........................46
5.1 Preface………………………………….…...............................46
5.2 Experimental Setup…...………………..…..............................46
5.3 Experimental Result and Discussion…….….......................…47
5.4 Experimental Result with Bit Loading and Discussion………..51
5.5 Summary…………………………………….............................56
Chapter VI. Conclusion…………………………………..........….57
Reference ...……………………………………………...................…58
Publication ...……………………………………………...............61

[1] D.K. Borah, A.C. Boucouvalas, C.C. Davis, S. Hranilovic, and K. Yiannopoulos, “A review of communication-oriented optical wireless systems,” EURASIP Journal on Wireless Communications and Networking, 2012:91, pp. 1-28, Apr. 2012.
[2] T. Komine and M. Nakagawa, “Fundamental Analysis for Visible-Light Communication System using LED Lights,” IEEE Trans. Consumer Electron., vol. 50, no. 1, pp. 100-107, Feb. 2004.
[3] T. H. Do, J. Hwang, and M. Yoo, ’’Analysis of the effects of LED direction on the performance of visible light communication system’’, Photonic Network Communication , 25,60-70,2013.
[4] Z. Wang, C. Yu, W. De Zhong, J. Chen, and W. Chen, “Performance of a novel LED lamp arrangement to reduce SNR fluctuation for multi-user visible light communication systems’’, Optics Express, 20, 4564-4573, 2012
[5] A. Shalash and K.K. Parhi, “Comparison of discrete multitone and carrierless AM/PM techniques for line equalization,” IEEE International Symposium on Circuits and Systems., 2, 560–563, 1996.
[6] A.H. Abdolhamid, D.A. Johns, “A comparison of CAP/QAM architectures,” IEEE International Symposium on Circuits and Systems., vol. 4, pp.316/1-316/3, Jun. 1998.
[7] T.N. Duong et al., “Adaptive Loading Algorithm Implemented in AMOOFDM for NG-PON System Integrating Cost-Effective and Low-Bandwidth Optical Devices,” IEEE PTL 21, 790-792, 2009.
[8] N. Al-Dhahir, “Single-carrier frequency-domain equalization for space-time block-coded transmissions over frequency-selective fading channels”, IEEE Communications Letters,5,304-306, 2001.
[9] M. K. Simon, and V. A. Vilnrotter, “Alamouti-type space-time coding for free-space optical communication with direct detection ”, IEEE Transactions on Wireless Communication, 4, 35-39, 2005.
[10] X. Li, R. Mardiing, J. Armstrong, “Channel Capacity of IM/DD Optical Communication Systems and of ACO-OFDM,” in Proc. IEEE International Conference on Communications (ICC 2007), 2007.
[11] 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 communications using a postequalized white LED,” IEEE Photon. Technol. Lett., vol. 21, no. 15, pp. 1063–1065, Aug. 1, 2009.
[12] Chien-Lan Liao, Yung-Fu Chang, ‘’High-Speed GaN-Based Blue Light-Emitting Diodes with Gallium-Doped ZnO Current Spreading Layer,’’ IEEE electron device letter, vol. 34, no, 5, May 2013.
[13] Qureshi, S.U.H, ‘’Adaptive equalization,’’ Proc. IEEE, 1985, 73, (9), pp. 1349-1387
[14] J. Armstrong, S. Member, “OFDM for Optical Communications,” IEEE J. Lightwave Technol. vol. 27, no. 3, Feb. 2009.
[15] Y.M. Lin, “Demonstration and Design of High Spectral Efficiency 4Gb/s OFDM System in Passive Optical Networks,” Proc. OFC, Mar. 2007.
[16] David Falconer, ‘’Frequency Domain Equalization for Single-Carrier Broadband Wireless Systems,’’ IEEE Communication Magazine, Apr.2002
[17] H.Witschnig, T.Mayer, ‘’ The advantage of a Known Sequence versus Cyclic Prefix in a SC/FDE System,’’ IEEE, 2002.
[18] S. M. Alamouti, ‘’A simple transmit diversity technique for wireless communication,’’ IEEE Journal on Selected Area in Communications, vol. 16, pp. 1451-8, 1998.
[19] Jean Armstrong , ’’Alamouti coding for indoor optical wireless communications using ACO-OFDM,’’ IEEE, 2009