室內可見光通訊系統(visible light communication, VLC)使用發光二極體(light emitting diode, LED)，不僅作為室內照明，同時當作傳輸資料之訊號源。一顆發光二極體(以下簡稱LED)可視為一個燈具。在一個室內空間中，會擺放多個燈具，以達到基本照明需求。
多燈具傳輸方式，大致可分為分時多址(time division multiple access, TDMA)、分頻多址(frequency division multiple access, FDMA)以及分碼多址(code division multiple access, CDMA)三大類。在本可見光通訊系統中，我們將空間內各個燈具載上相同的訊號，並且使用相同頻段同時進行傳輸。接收器將收到來自各個燈具傳輸的訊號，每個燈具到接收器的距離不同，訊號抵達接收端的時間無法一致，導致訊號之間彼此會有干擾的現象產生。為解決干擾問題，本論文使用多載波分碼多址(multi-carrier CDMA)的技術，配合金氏碼(Gold code)的特性，使得接收端不同步的混合訊號能夠還原，得到原始訊號，整個室內空間都可獲得良好的通訊品質。

In visible light communication (VLC) system, LEDs are used for illumination as well as the transmitted sources of communication. In an indoor space, there are multiple LEDs set to supply basic lighting requirements.
The methods of transmission for multiple LEDs are usually divided into three ways: time division multiple access(TDMA), frequency division multiple access (FDMA), and code division multiple access(CDMA). In this thesis, we mainly use CDMA with orthogonal frequency division multiplexing(OFDM) technique to transmit signals from each LED at the same time and same frequency band. At the receiver end, we will detect all signals with multipath interference. Due to the feature of CDMA, we can separate each signal from each LED. On the other hand, since the distances from each LED to photon detector(PD) are not the same, we use asynchronous CDMA instead of synchronous CDMA. Thus, we don’t need to consider time synchronization between LEDs to extract the original signal. Therefore, we can get well signal performance in overall space.

中文摘要 i
ABSTRACT ii
致謝 iii
目錄 iv
圖目錄 vi
表目錄 viii
第一章 緒論 1
1.1 前言 1
1.2 研究目的與動機 2
1.3 論文架構 3
第二章 正交分頻多工與分碼多址 5
2.1 正交分頻多工(OFDM) 5
2.2 多碼分址(code division multiple access, CDMA) 7
2.2-1 多址傳輸系統 7
2.2-2 正交碼 9
2.2-3 非正交碼 10
2.2-4 金氏碼(Gold code or Gold sequence) 11
第三章 可見光之照明與干擾 16
3.1 照度測量 17
3.2 多燈具干擾 20
第四章 傳送與接收架構 22
第五章 可見光通訊實驗 24
5.1 可見光通訊實驗架構 24
5.2 實驗結果 26
5.2-1 加入金氏碼後之星座圖 26
5.2-2 通道響應 28
5.2-3 示波器之取樣頻率對實驗的影響 29
5.2-4 4QAM,16-subcarrier無布幕實驗結果 30
5.2-5 8QAM,16-subcarrier無布幕之實驗結果 40
5.2-6 8QAM,16-subcarrier有無布幕之實驗結果比較 47
5.2-7 8QAM,16-subcarrier實際移動光偵測器之實驗結果比較 52
第六章 結論 55
參考文獻 56

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