隨著人們對網路頻寬以及系統彈性的需求愈來愈大，採用正交分頻多工(Orthogonal Frequency-Division Multiplexing, OFDM)技術可以實現彈性頻譜配置的光纖網路，因為可以支援更大的網路傳輸量，而且在頻寬的使用上也更具彈性，故已經成為了一個很有吸引力的架構，很有可能成為新一代的網路骨幹。
本篇論文主要在探討如何改良現有的彈性光纖網路(Elastic Optical Networks, EON)架構，並提出一個可以因應動態網路流量需求的繞徑與頻譜配置(Routing and Specturm Assignment, RSA)演算法。我們的演算法依序可分為預處理、輔助圖建立、Bellman-Ford演算法[1-3]找rouing路徑三個部份。我們為我們的網路架構設計了輔助圖和polices。我們會根據polices決定輔助圖上的edges與edges上的weight，最後再用Bellman-Ford演算法為當前的網路流量需求找到routing路徑。目標是希望能更有效用資源，並達到更低的blocking ratio。
另外，我們也考慮到了physical impairment的問題，用數學模型來估算各種網路流量需求在不同modulation format之下所能傳輸的距離，讓我們的實驗模擬更貼近實際環境。實驗結果顯示，我們可以達到更低的blocking ratio。

As the continual growth of Internet traffic and the need for flexibility, a spectrum–flexible optical networks based on Orthogonal Frequency-Division Multiplexing (OFDM) transmission technologies has been proposed as a promising solution for the backbone in the next-generation network because of its large transport capacity and bandwidth flexibility.
This paper studies how to improve the exsiting OFDM-based Elastic Optical Networks (EON) architecture, and presents a Routing and Spectrum Assignment (RSA) algorithm for the dynamic connection requests. Our algorithm can be divied into three stages: Preprocessing, Auxiliary Graph Construction, and Routing Path Finding with Bellman-Ford Algorithm [1-3]. We design the auxiliary graph and polices for our network architectures. Policies can be achieved by properly adjusting the edge weights in the auxiliary graph, and then it’s possible to find the routing path for the current connection request with Bellman-Ford algorithm. Our objective function is to efficiently utilize the spectrum and transceiver resource in order to minimize the blocking ratio of the connection requests.
In addition, we also consider the physical impairment issues. A mathematical model is utilized to estimate the network dependent Quality-of-Transmission and the transmission reach of the various modulation formats for the connection requests in order to make our simulation much closer to the real-world environment. Simulation results show we can achieve a lower blocking ratio than the previous works.

第一章 簡介 1
第二章 架構 3
2.1. OFDM-based Sliceable EON 3
2.2. OTDM/OFDM-based Sliceable EON 5
第三章 輔助圖 9
第四章 Policies 16
4.1. 第一部份：決定Physical Links Spectrum 16
4.2. 第二部份：決定Candidate Path Priority 18
4.3. 第三部份：決定Edge Weight for Bellman-Ford 19
第五章 Heuristic演算法 23
第六章 實驗結果 26
6.1. 網路流量需求的產生及相關參數設定 26
6.2. OFDM-based Sliceable EON加入OTDM後之比較 27
第七章 結論 28
參考文獻 29

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