近年來在第一英哩光接取網路(first　mile　optical　access　networks)上的個人通訊隱私越來越到重視，因此對於提升網路上的安全機制是迫切需要的。為了更進一步地提升網路資料的機密性，本論文將ㄧ種新式的可重置編碼化分波多工技術架構在乙太被動式光纖網路上(reconfigurable　coded　wavelength-division-multiplexing　over　Ethernet　passive　optical　network,　reconfigurable　coded　WDM-EPON)，預防竊聽者偷取光纖到家網路裡每個用戶的重要資訊。此外，可重置編碼化分波多工技術不僅能提供目前接取網路所無法提供的資料安全，另外還擁有高速、突發式非同步傳輸(burst　asynchronous　transmission)、靈活的網路設計以及可避免網路上的資料碰撞(data　collision)，這些重大優勢。因此可重置編碼化分波多工技術將可能被視為解決乙太被動式光纖網路的最佳方案之ㄧ。

　　在本論文中，我們僅僅利用一組簡單的可重置編解碼器架構，便能夠提供與傳統較複雜的編碼化分波多工技術具同樣良好的資料機密性。因此，我們並不採用複雜的跳頻(wavelength-hopping)、展時(time-spreading)甚至頻域相位編碼(spectral　phase)，這些擁有巨大的碼空間但較難以實現編碼技術。而是利用頻域振幅編碼(spectral　amplitude　coding,　SAC)的方式將最大長度序碼(maximal-length　sequence　codes,　M-sequence)來當做每個使用者的光位址序碼　(optical　address　codewords)。再者，我們可將光切換器、控制暫存器與陣列波導光柵(Arrayed-Waveguide　Grating,　AWG)所具有的波長循環特性結合，整合成一組可重置化的編解碼器(reconfigurable　encoder/decoder,　codec)。因此，我們所提出的架構不但能提升網路的安全性還能使得整個系統變得小巧且簡單，這是因為所有的使用者可以共用一組集中在同一個區域的編解碼器。

　　再者，目前大部分有關於編碼化分波多工技術文獻裡，以往只能憑藉著直覺與不嚴謹的概念來評估本身的安全性，只有極少數能確實量化出編碼化分波多工技術所能提供的機密性究竟有多高。因此，本論中亦提出ㄧ套對於可重置編碼化分波多工技術在預防竊聽上的定量與定性分析方法。在考慮網路遭受竊聽之觀點下，我們將計算出機密性程度(degree　of　confidentiality,　DOC)、暴力法搜尋時間(brute-force　searching　time)與預期警戒時間(anticipative　warning　time)等，一系列的評估方式證實架構可重置編碼化分波多工於乙太被動式光纖網路，在相較於傳統的光纖到家網路之下，確實能夠大幅提升網路資料的機密性。

　　With　regard　to　communication’s　privacy　in　the　first/last　mile　optical　access　networks,　the　security　mechanism　is　in　need　of　enhancement　urgently.　In　this　thesis,　the　reconfigurable　coded　wavelength-division-multiplexing　over　Ethernet　passive　optical　network　(reconfigurable　coded　WDM-EPON)　is　presented　to　enhance　the　confidentiality.　Besides,　the　reconfigurable　coded　WDM　scheme　also　has　several　other　advantages　such　as　high　speed,　more　flexibility　in　network　design,　burst　asynchronous　transmission　and　data　collision　prevention.　Thus,　the　proposed　scheme　will　be　one　of　promising　candidates　for　EPON　system.

　　In　this　thesis,　we　develop　merely　one　simple　reconfigurable　encoder/decoder　(codec)　architecture　instead　of　other　complicated　coded　WDM　schemes　to　generate　excellent　data　confidentiality.　Rather　than　employing　wavelength-hopping,　time-spreading　or　spectral　phase　taxing　coding　approaches,　which　all　involve　huge　code　space,　this　thesis　applies　spectral　amplitude　coding　(SAC)　with　maximal-length　sequence　(M-sequence)　codes　as　optical　address　codewords.　In　addition,　we　integrate　optical　switches,　control　register　and　inherent　cyclic　periodic　properties　of　Arrayed-Waveguide　Grating　(AWG)　routers　into　AWG-based　reconfigurable　codec.　Therefore,　not　only　can　the　proposed　scheme　prevent　current　access　network　form　eavesdropping　but　it　can　also　maintains　the　benefits　of　a　more　compact　size　and　a　simpler　implementation　because　all　users　can　share　a　single　codec　pair　and　the　AWG-based　reconfigurable　codec　are　centralized　at　a　common　location.

　　Furthermore,　most　of　coded　WDM　in　literature　never　evaluated　the　performance　of　confidentiality　and　they　are　only　dependent　on　imprecise　intuition　and　notion.　In　our　proposed　scheme,　both　qualitative　and　quantitative　analyses　of　protecting　against　eavesdropping　also　investigated.　Under　eavesdropping　with　a　series　of　evaluation　strategies　such　as　degree　of　confidentiality　(DOC),　brute-force　searching　time　and　anticipative　warning　time,　the　proposed　reconfigurable　coded　WDM-EPON　scheme　is　demonstrated　that　the　confidentiality　will　be　significantly　increased　by　implementing　reconfiguration　of　codec.

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