我們提出並以實驗呈現基於多頻帶直接檢測光學正交分頻多工(DDO-OFDM)系統，傳送可調性調變(AM)偏振態多工(PDM)光纖載中頻訊號(IFOF)，達到免偏振態追蹤的下傳系統及偏振態無感的OOK上傳系統。由於不需追加偏振態追蹤的機制，因此每一個無線接取單元(RAU)的設備簡單化，整個無線接取單元也更具有經濟效應及低功率損耗。另外，結合了集中式無線電接取網路(C-RAN)的架構，建立了一個靈活度高和複雜度集中之行動網路前段，這將有希望成為下一代行動通訊網路的參考指標。
在下傳系統當中，只需在每一個接收端設置一個簡單光學濾波器，就可以成功地解調相對應的偏振態多工及多頻帶訊號。我們以實驗實際呈現頻寬為3.5GHz且載有大約50GHz資訊量的可調性調變多頻帶OFDM訊號，並傳送於25km單模光纖中。由於使用偏振態多工的技術頻譜效應倍增，以可調性調變技術使傳送資訊量再增加8Gb/s。另外，此系統還提供4dB power margin，能更進一步支持無線通訊的服務[1]。對於上傳系統直接再利用兩正交偏振態載波，再不追加濾波器或是偏振態控制器的狀況下，能成功地使用對偏振態靈敏的MZM光學調變器達到偏振態無感的效果。由結果顯示，與傳送對齊晶體光軸的單偏振態訊號相比，大約有1.8dB功率損耗。整體而言，偏振態追蹤的技術不必使用，因此建立了真正的無偏振態追蹤的網路前段系統。

We propose and experimentally demonstrate a polarization-tracking-free polarization division multiplexing (PDM) intermediate frequency over fiber (IFoF) based on multiband direct detection optical orthogonal frequency division multiplexing (DDO-OFDM) with adaptive modulation (AM) technique downstream, as well as polarization insensitive on-off-keying upstream. The polarization tracking mechanism is eliminated, hence the complicated cell sites are simplified and letting more cost-effective and power-efficient for every radio access unit (RAU). Moreover, under the C-RAN architecture the mobile fronthual is thus establish with high spectra flexibility and complexity centralized which will be a promising selection for next generation mobile communication.
In the downstream system, only a simple optical filter at each receiver can passively demultiplex the corresponding signal band in both PDM scheme and multiband scheme. An adaptively modulated multiband OFDM signals with 3.5-GHz bandwidth, 50-Gb/s transmission 25-km single mode fiber is experimentally demonstrated. A spectral efficiency is doubled with applied PDM technique and data capacity is 8-Gb/s increased compare with employing AM or not. Furthermore, it provides 4 dB power margins, where may support wireless transmissions[1]. In the upstream generation, the polarization insensitive is implemented for using MZM by directly reuse the two orthogonal carriers without additional filtering or polarization controlling. The results show a 1.8dB power penalty with respect to those with traditional best polarization aligned mechanism, which can be negligible. The polarization tracking mechanisms are out of consideration and establish a true polarization tracking free mobile fronthaul system.

第1章 緒論 1
1.1 前言 1
1.2 研究目的與動機 3
1.3 論文架構 6
第2章 可調性調變於直接偵測光學正交分頻多工系統 7
2.1 正交分頻多工系統 7
2.1.1 分頻多工與正交分頻多工 7
2.1.2 正交分頻多工系統調變與解調原理 9
2.2 電-光調變器 (Electro-optical modulator) 11
2.2.1 馬赫-詹德的調變器(Mach-Zehnder Modulator ,MZM) 12
2.3 直接偵測光學正交分頻多工(DDO-OFDM)系統架構 15
2.4 可調性調變系統 (Adaptive modulation) 18
2.4.1 可調性演算法 (Adaptive Algorithm) 19
第3章 無偏振態追蹤PDM 多頻帶 IFoF AM-DDO-OFDM下 22
3.1 光纖載中頻訊號(Intermediate frequency over fiber, IFoF)/光纖載射頻訊號(Radio frequency over fiber, RFoF) 22
3.2 偏振態多工 (Polarization Division Multiplexing, PDM) 23
3.3 多頻帶直接偵測OFDM 系統 26
3.4 無偏振態追蹤PDM Multiband OFDM下傳的機制 28
3.5 偏振態無感的上傳機制 30
第4章 實驗架構及結果 32
4.1 下傳行動網路前段 33
4.1.1 實驗架構 33
4.1.2 實驗結果 37
4.2 上傳行動網路前段 49
4.2.1 實驗架構 49
4.2.2 實驗結果 53
第5章 結論 55
參考文獻 56

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