因為成本考量，在OFDM PON中主要使用雙頻帶強度調變與直接接收之架構。然而傳輸光纖後，因色散所造成的RF power fading會使OFDM各個使用者受到不同衰減的影響而有不同的表現，且衰減嚴重的使用者將無法達到FEC threshold。目前大多數的研究者在OLT端根據不同的傳輸距離對訊號做不同的設計，來克服RF power fading的問題；但是相對的也提升了訊號設計上的複雜度以及硬體上的成本。因此在本論文中，我們提出了透過MC-CDMA技術將各個使用者的信息用正交碼展開，使所有使用者去共同承擔RF power fading的響應而有相同的表現。
在本論文中我們透過模擬與實驗印證了MC-CDMA訊號是一個通用於B2B至100km傳輸的設計，且在接收端我們提出了MMSE等化器並且結合了MCI消除之訊號處理方式，在長距離的被動光學網路下更進一步提升了系統表現。經由實驗結果證實即使受到將近20dB的RF power fading，經由我們提出的方法可提供21.7dB的power budget且100km內傳輸與B2B只有2dB的差距。

Orthogonal frequency division multiplexing (OFDM) passive optical network (PONs) implementing with double-side band intensity modulation and direct detection (IMDD) is considered as a cost-effective design. However, radio frequency (RF) power fading induced by chromatic dispersion causes non-uniform receiving performance among users. Generally speaking, user who suffered from the most serious fading cannot reach the specific forward error correction (FEC) threshold. To solve above dilemma, most of researchers adaptively design signal level in optical line terminal (OLT) depending on different transmission distance. However, such adaptive approach hugely enhances the system complexity and hardware costs. Therefore, we employ multicarrier code division multiple access (MC-CDMA) technique to equalize users’ received performance via spreading subcarriers’ data with orthogonal code. After frequency spreading, all users would suffer from the same RF power fading response and thus have the same performance.
In this thesis, we simulatively and experimentally proof that the proposed MC-CDMA PON could achieve a universal transmitter design for users ranging from back-to-back to 100 km. Meanwhile, we apply minimum mean square error (MMSE) equalizer, combining with multi-code interference (MCI) cancellation digital signal process (DSP) to further enhanced system performance in a long reach PON. Our experimental results reveal that even under about 20 dB RF power fading, the proposed scheme can still provide 21.7 dB power budget and only about 2 dB sensitivity deviation is observed.

第1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2章 多載波之分碼多重存取系統 4
2.1 正交分頻多工(OFDM)系統 4
2.1.1 分頻多工與正交分頻多工 4
2.2 分碼多址(CDMA)系統 7
2.2.1 多址傳輸系統 7
2.2.2 應用在CDMA的編碼技術 8
2.2.3 CDMA加碼與解碼的原理 13
2.3 MC-CDMA系統 15
2.3.1 MC-CDMA的編碼器與解碼器 15
2.3.2 DS-CDMA和OFDM以及MC-CDMA的頻譜分配方式之比較 16
第3章 光學雙頻帶強度調變之效應 18
3.1 光學調變器 18
3.2 光學雙頻帶因色散造成的功率衰減 21
第4章 接收端檢測與多碼干擾消除 24
4.1 接收端檢測器 24
4.1.1 強制逼零等化器(ZF) 25
4.1.2 最小均方差等化器(MMSE) 25
4.2 多碼干擾消除 27
第5章 MC-CDMA模擬與實驗 29
5.1 MC-CDMA模擬與實驗架構 29
5.2 利用空白頻帶避開RF power fading之實驗 30
5.2.1 實驗-參數設計 30
5.2.2 實驗-頻譜圖與subcarrier vs. BER曲線 31
5.2.3 實驗-各距離之系統表現 34
5.3 使用DSP方法克服RF power fading之模擬 36
5.3.1 模擬-參數設計 36
5.3.2 模擬-頻譜圖 37
5.3.3 模擬-整體系統表現 37
5.3.4 模擬-各個使用者表現 44
5.4 使用DSP方法克服RF power fading之實驗 47
5.4.1 實驗-參數設計 47
5.4.2 實驗-頻譜圖與subcarrier vs. BER曲線 47
5.4.3 實驗-整體系統表現 49
5.4.4 實驗-各個使用者表現 54
5.4.5 實驗-各距離傳輸之power budget 56
第6章 結論 58
參考文獻 59

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