在間歇連結的移動式網路(Intermittently Connected Mobile Networks，ICMNs)環境下，大部分的時間是不存在一條自來源端至目的端的完整路徑或者說這些路徑非常地不穩定，可能在被發現後(甚至是發現時)路徑又發生改變或是斷裂的狀況。這種環境可能發生在野外探勘或是軍事戰場上，基地台因為地形的阻礙、距離太遠或是遭受破壞，導致網路上節點必須透過移動的方式找到一條路徑與其他節點作聯繫。
為了達到這個目的，大部分的方法皆採用flooding-based的方式。這種方式雖然可以提高將資料送達目的端的機率，然而卻也造成了嚴重的網路資源浪費。在本篇論文中提出了一種叫Spray and Hop的方法，它採用了一種叫做Spray的控制機制。這個機制是利用產生一種叫做forwarding token的小封包來控制網路的封包氾濫情形，同時也能更效率地將資料散播出去。此外，本論文為了提升資料傳送的成功率，還提出一種混合式的Utility-based機制，這個機制是透過節點本身的資訊來判斷下一個最佳的candidate relay node，而不是利用直接傳送的方式造成網路的延遲。
本論文提出的Spray and Hop機制擁有很高的擴充性，在大型或小型的網路拓樸皆有不錯的效能表現，且並不需要額外的網路資訊即能達到較高效能。經由模擬，相對於其他flooding-based機制，在網路的傳送封包數(Transmissions)及延遲(Delay)方面，確實都能獲得不錯的效益。

In intermittently connected mobile networks (ICMNs), where most of the time there does not exist a complete path from source to destination, or such a path is highly unstable and may change or break after it has been found (or even while being found). This kind of environment may apply to wildlife tracking sensor networks or military networks, and node on this network must find a route and communicate with other nodes by the way of moving, because the base station is too far away or destroying.
In order to achieve this purpose, researchers have suggested using flooding-based routing schemes. Although these ways have high probability of delivery, but they waste a lot of network resources.
This thesis proposes a routing protocol in ICMNs named Spray and Hop, and it has adopted a kind of mechanism which is named Spray. The method can reduce network overhead, and broadcast efficiently at the same time by using one name little control packages named forwarding token. In addition, in order to improve the success rate of delivery, we still apply a kind of composite Utility-based mechanism. This mechanism is to select the next best candidate relay node through node's own information, not utilizing the way of direct transmission.
Spray and Hop mechanism has highly scalability, that is, this mechanism has good performance in dense and sparse networks, and does not need extra network information. Simulation results show that Spray and Hop has good performance in packet transmissions and end-to-end delay indeed, comparing to other flooding-based mechanisms.

第一章 導論 1
1.1 前言 1
1.2 研究動機 4
1.3 論文架構 5
第二章 相關研究與背景 6
2.1 Disruption Tolerant Networks (DTNs) 6
2.2 Mobility-Assisted Routing Protocol 8
2.2.1 Single-Copy Routing 10
2.2.2 Multiple-Copy Routing 13
2.3 Utility Function 14
第三章　改進機制：Spray and Hop 16
3.1 Scheme Preview 17
3.2 Spray Phase 19
3.3 Hop Phase 26
第四章 模擬結果與討論 30
4.1 模擬環境與參數設定 30
4.2 模擬圖表及討論 32
第五章 結論 40
參考文獻 41

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