為因應被動式光網路(Passive Optical Network, PON)中多媒體寬頻暨高速網路的需求，本論文擴展運用光頻域振幅(Spectral Amplitude Coding, SAC)分碼多重擷取技術(code-division multiple-access, OCDMA)於光纖到府(Fiber-to-the-Home, FTTH) 接取網路。

基於中央機房(central office, CO)的光線路終端(Optical Line Terminal, OLT)連結至各光網路單元(Optical Network Unit, ONU)其不同的地理性分佈(geographical distribution)所呈現出帬聚共享(central-shared type)或個別型態(single type)之使用者(subscriber)。本論文提出不同的編、解碼裝置的網路拓樸(topologies)以滿足各ONU使用者的靈活性(flexibility)或私密性(confidentiality)等不同的需求。對於個別型態的ONU使用者；我們延伸運用布雷格光纖光柵(Fiber Bragg Grating, FBG)預寫Walsh-Hadamard碼以實現混合式光頻偏極化與振幅編碼架構(hybrid Spectral Polarization/Amplitude Coding scheme, hybrid SPC/SAC)。對於帬聚共享型態的ONU使用者；我們延伸運用陣列光纖光柵(Arrayed Waveguide Grating, AWG)預寫M-sequence碼以實現私密性保護的機制。再者對應於提出的各式架構；我們分別探討各其多重存取干擾(multiple access interference, MAI)暨相位導致振幅失真(phase induced intensity noise, PIIN)的效應，以印證其在錯誤率(bit error rate, BER)為10-9的需求下，系統架構增加提高ONU使用者(simultaneous active users, ONUs)數量的有效性。以實現最低成本(low cost)與最高頻譜效能(spectral efficiency)的目標。

對於個別型態(single type)之使用者，我們在相同光頻譜內嵌入彼此正交極化的光波，以實現互補式光頻域極化編碼(complementary spectral polarization coding, SPC)。相較於傳統超強碼(bipolar super code)使用串接式互補碼(cascaded complementary code)來實現雙極性光頻碼(bipolar optical code)的架構而言，光頻域極化編碼(SPC)可以獲得兩倍的頻譜效能暨克服光頻譜不平坦的問題。

為了進一步改善光頻域極化編碼架構的相位導致振幅失真(Phase induced intensity noise, PIIN)效應。我們提出混合式光頻極化與振幅編、解碼架構(hybrid spectral polarization and amplitude coding scheme, hybrid SPC/SAC scheme)。其主要藉由Walsh-Hadamard矩陣所衍變而生成之正交三元序列(orthogonal ternary sequences)做為光位址指配碼。相較光頻域極化編碼(SPC)增加了null wavelength (0)的元素。因此使得波長疊加在光平衡檢測器的碰撞減少了，而更能抑制PIIN暨可提供更多同時使用者(simultaneous active users)的數目。

對於光纖到府網路中在地理上具有群聚共享型的使用者，我們率先運用陣列波導光纖光柵路由器既有的循環(cyclic shifting)與自由頻寬間距(Free Spectral Range, FSR)的特性，使更多的使用者能共享光纖光柵路由器。相較於傳統分波多工以太被動光纖網路(WDM-EPON)架構而言，本混合式光分波與分碼多重擷取架構更可維持陣列波導光纖光柵路由器在數量上的精簡，並使光纖到府網路更具可擴充性與靈活性。

為了提高群聚共享型的使用者之網路隱私權與私密性。我們提出較少的最大長度序碼(M-sequence code) 配合動態式可變異性光頻碼的機制。其中，動態式可變異性機制主要係由一組電移位暫存器(electrical shift registers)與一系列光互換開關(optical switches)與動態變換光頻碼演算法(dynamic codeword modification)所實現。當設想竊取者(eavesdropper)擁有不同的攻擊能力時，將所偵測到各分佈於傳輸通道之波長的平衡度(the degree of weighted load balance)作為觸發光頻碼變換的指標。當滿足光頻碼變換的指標時，我們在「最小的波長分怖平衡度」與「電移位暫存器的最小位移量」彼此兩難困境的問題(tradeoff problem)取得平衡點以決定變換至那個光頻碼。由結果顯示：動態式光頻碼變換機制比固定式光頻碼變換的方法來得更有效率，也使動態式可變異性光頻碼的機制在網路隱私權與私密性的保護更為優越。

綜合上述，為提供分時多工與分波多工以太被動光纖網路(Ethernet Passive Optical Network, EPON)之外的另一種選擇架構，我們提出多樣需求的光頻域分碼多重擷取技術的各式拓樸以應用於光纖到府網路。相較分時多工與分波多工技術，此架構可以解決同時間在OLT中央機房與ONU用戶端之間資料傳遞的碰撞問題以降低系統的處理時間達到高速網路的需求。而且在動態式可變異性光頻碼的機制下，更可確保光纖到府網路的隱私權與私密性。

In recent years, Ethernet Passive Optical Networks (E-PONs) have emerged as the method of choice for providing broadband, high-speed services over the last (first) mile. This dissertation discusses the implementation of new spectral amplitude coding techniques based on Spectral Amplitude Coding Optical Code-Division Multiple-Access (SAC-OCDMA) schemes over Fiber-to-the-Home (FTTH) networks.

According to the geographic distribution of the Optical Network Unit (ONU) groups in the network, this dissertation classifies ONUs (i.e. subscribers) as either central-shared (e.g. a group of ONUs within an office or an apartment complex) or single (e.g. individual ONUs within a home). Various topologies are proposed to meet the differing requirements of the two ONU types for flexibility and confidentiality. For the single-type ONU, Fiber Bragg Grating-based encoder/decoders (FBG-based codecs) are configured using Walsh-Hadamard code as the signature address code, Conversely, for central-shared ONUs, Arrayed Waveguide Grating-based encoder/decoders (AWG-based codecs) are configured using maximum length sequence code (M-sequence code) as signature address code. The problems of Multiple Access Interference (MAI) and Phase-Induced Intensity Noise (PIIN) are investigated in the various FBG- and AWG-based codec schemes presented in this dissertation. Overall, the results show that the proposed schemes allow a significant increase in the number of simultaneous active users (i.e. ONUs) for a bit error rate (BER) of 10-9.

The proposed Spectral Polarization Coding (SPC) scheme is incorporated with polarization coding as the signature address code of the single type ONUs. Here, unipolar Walsh-Hadamard code is employed as the signature address to allocate each specified wavelength an individual vertical or horizontal State-of-Polarization (SOP). The numerical results demonstrate that the proposed approach achieves a better double spectral efficiency than conventional supercode.

We propose an enhanced hybrid Spectral Polarization and Amplitude Coding (hybrid SPC/SAC) scheme designed to improve the performance of the SPC scheme by further reducing the number of wavelength collisions. Compared to the SPC scheme, the distinguishing feature of the hybrid SPC/SAC scheme is its use of null wavelengths, which significantly reduces the number of wavelength collisions in the photo-detector, and hence reduces the PIIN noise.

For central-shared type ONUs, we present a Wavelength-Division Multiplexing and OCDMA (hybrid WDM/OCDMA) scheme for central-shared ONUs (subscribers). In the proposed approach, the periodic cyclic and Free-Spectral-Range (FSR) properties of AWG routers are exploited to partition the total ONU capacity in the network into different groups in accordance with the subscribers’ geographical locations. It is shown that while the number of AWGs in the proposed scheme is comparable to that of conventional WDM-EPON schemes, the hybrid WDM/OCDMA scheme has improved flexibility, confidentiality and scalability characteristics.

In order to enhance the confidentiality of AWG-based codecs for central-shared type ONUs, the dynamic reconfigurable coding/decoding scheme is implemented by using optical switches and simple electrical shift registers. In addition, a dynamic codeword modification policy is proposed which identifies the code matrix assignment which minimizes the Degree of Weighted Load Balance (DWLB). The evaluation results demonstrate that the reconfiguration policy outperforms one class of static policies both in terms of the DWLB and the number of register shifts required to reconfigure the code matrix assignment.

This dissertation proposes various SAC-OCDMA techniques over FTTH networks as alternatives to traditional Time-Division-Multiplexing (TDM-) and WDM-EPON methods. In general, the results show that the proposed schemes not only reduce the processing time and resolve the collision problem resulting from the simultaneous arrival of active packets at the optical line terminal (OLT) or ONUs, but also significantly improve the data confidentiality characteristics of FTTH networks.

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