關鍵字
被動光網路、波長分波多工被動光網路、時間分割多工被動光網路、光接取網路、饋送光纖、分散光纖、陣列波導光柵、光終端設備、光網路元件、不妥善率

　　隨著使用者對於頻寬的需求度急速的增加，實作具高頻寬特性的光接取網路已經是勢在必行的趨勢。光接取網路主要分為波長分波多工被動光網路(WDM-PON)及時間切割多工的被動光網路(TDM-PON)。有別於在傳統的時間切割多工的被動光網路(TDM-PON)中，所有的光網路元件只能共享同一波長的頻寬。在波長分波被動光網路中，所有的光網路元件則因為都可以獨自享有特定的波長並同時傳送資料給光終端設備而具有高頻寬的特性。但越高的頻寬特性通常也意味著錯誤發生後所造成的損害會越大，因此如何設計出一個具有高可用性的波長分波多工被動光網路已是個迫在眉梢的問題。
　　在現有的相關研究中，已有一些學者提出對於波長分波多工被動光網路的保護架構。但在大多數的研究中，所提的架構僅具有部份的保護能力。不是只具有光終端設備與遠端節點間的饋送光纖保護能力(如: 無限定波長使用的保護架構)，就是只具有遠端節點與光網路元件間的分散光纖保護能力(如: 群組保護架構、中央控制保護架構、1:N保護架構)，而唯一能提供饋送光纖與分散光纖全保護能力的中央路由保護架構，卻又因為此架構對於光纖與設備的需求數目較多，使得建構成本太過於高昂而難以實行。
　　本篇論文的目的在於建構出一個成本低廉且具有饋送光纖與分散光纖全保護能力的保護架構。我們將利用陣列波導光柵(AWG)的不同輸入埠的波長分配特性與循環特性，並以1:N保護架構的波長分配方式為基礎來延伸波長的分配方式，重新規劃光網路元件間的相互連結方式，再透過對光終端設備與光網路元件結構的重新設計，達成我們預期的目標。值得一提的是，在與其他保護架構相比較之下，我們所提出的完全保護架構除了具有建構成本相當低廉的特性之外，所需的波長使用數更是只有上述那些保護架構的一半而已。且由於此保護架構對饋送光纖與分散光纖都能提供保護的能力，因此會使得架構的不妥善率極低，而讓此保護架構具有高可用性。最後本論文還會針對所提出的保護架構，分析其能量盈餘(Power Budget)，以用來驗證此架構的可行性。

Keywords:
PON (Passive Optical Network), WDM-PON (Wavelength-Division-Multiplexing PON), TDM-PON (Time-Division-Multiplexing PON), OAN (Optical Access Network), Feeder Fiber, Distribution Fiber, AWG (Array Waveguide Grating), OLT (Optical Line Terminal), ONU (Optical Network Unit), Unavailability

　　With the rapidly increasing demand for bandwidth, implementation of a high-bandwidth optical access network (OAN) has become an inevitable trend in the future. Optical access networks can be classified into wavelength-division-multiplexing passive optical networks (WDM-PON) and time-division-multiplexing passive optical networks (TDM-PON). Unlike the traditional TDM-PON that all optical network units (ONUs) share the bandwidth of one wavelength, WDM-PON can achieve the high bandwidth property since each ONU can use its dedicated wavelength independently and transmit data to the optical line terminal (OLT) simultaneously. But the higher bandwidth may cause more serious damage especially if any failure occurs. Thus, how to design a highly available WDM-PON becomes the most important issue.
　　Many protection architectures for WDM-PON have been proposed in the previous studies. But most of them provide the partial protection capability. For example, only feeder fiber protection is provided in the study “a Survivalbe WDM-PON with Colorless ONUs or only distribution fiber protection is provided in the studies “Group Protection Architecture”, “Central Control Protection Scheme”, and “1:N Protection Scheme”. The previous study “Survivable Network Architecture for WDM PON” is the only one that can provide both protection to feeder fiber and distribution fiber. However, the cost of device requirement for this full protection architecture is too high to implement.
　　The aim of the current study is to construct a WDM-PON architecture with less cost and full protection capability. The proposed protection scheme utilizes the cyclic property of array waveguide grating (AWG), extends the wavelength assignment of “1:N Protection Scheme”, reorganizes the connection pattern among the ONUs and redesigns the architecture of OLT and ONU to achieve the goal. Compared with the previous protection schemes, the proposed scheme can provide the full protection without incurring more construction cost and need only half number of wavelengths required by the previous protection schemes. Furthermore, the unavailability of the proposed scheme is shown to be lower than other protection scheme due to the full protection capability. Finally, the power budget is also evaluated to show the feasibility of the proposed scheme.

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