無線隨意網路中以連通支配集(connected dominating set)特性，建立虛擬骨幹(virtual backbone)的方式，可以有效減少廣播封包在網路中負擔的成本與能量的消耗。近年來，許多虛擬骨幹的建立方法陸續被提出，但是在這些方法中，很少有提到當網路拓樸改變，虛擬骨幹維護的議題。因為在無線隨意網路和無線感測網路中，節點的移動或是關閉造成網路拓樸改變是常常發生的，缺乏維護機制會使虛擬骨幹遭到破壞。本文提出一套維護虛擬骨幹的機制，利用修復網路上的斷裂鏈節，確保當網路拓樸發生改變時，虛擬骨幹架構得以維持。斷裂鏈節的修復，依據斷裂鏈節在虛擬骨幹中的角色，而有不同的作法。節點在維護虛擬骨幹的過程中，考慮到了鄰居資訊、虛擬骨幹的性質和已存在的虛擬骨幹架構，所以使我們提出的方法有很高的局部化程度。不管其虛擬骨幹的建立方法為何，我們的虛擬骨幹維護機制，可以套用在任何存在虛擬骨幹的網路之中，而且不會加大虛擬骨幹建立方法的複雜度。ns-2上的模擬結果顯示當網路節點密度較高和節點變動較小時，本文所提出的方法在封包消耗量與參與節點數上表現較其他方法好。

Using connected dominating set as a virtual backbone in ad hoc networks has the advantage of reducing both communication overhead and power consumption. Many virtual backbone (VB) construction methods have been proposed in recent years, but few of them focus on the maintenance issue. Since the network topology may dramatically change due to node mobility or switch off in mobile ad hoc networks (MANETs) or wireless sensor networks (WSNs). In this paper, we propose a localized virtual backbone maintenance scheme to retain the virtual backbone stable when network topology changed. Our method maintains the VB by repairing the broken link in the network. According to the broken link’s role in the VB, we use different ways to repair. Because the consideration for the broken VB’s property in the network, our maintenance method have more localized behavior. Our algorithm can be applied to any topologies with a VB structure, no matter what VB formation methods were used. And the complexity of proposed algorithm will not increase the complexity of VB formation methods. The simulation results on ns-2 demonstrate that our scheme outperforms other approaches in a dense and low mobility network environment in terms of packet consumption and number of involved nodes.

論文審定書 ii
致 謝 iii
摘 要 iv
Abstract v
圖次 x
表次 x
字母縮寫對照表 xi
第一章 導論
1.1 簡介 1
1.1.1 無線網路的通訊模式 3
1.1.2 IEEE 802.11定義的無線網路架構 7
1.2 無線隨意式網路背景與介紹 9
1.3 研究動機 12
1.4 論文架構 12
第二章 背景及相關研究
2.1虛擬骨幹的性質 13
2.2建立虛擬骨幹的好處與問題 16
2.3虛擬骨幹的建立 18
2.4虛擬骨幹的維護 19
第三章 系統之架構與運作
3.1 設計動機及方向 22
3.2 功能及名詞釋義 24
3.3 協定機制 25
3.3.1 網路模型 25
3.3.2 虛擬骨幹維護機制 26
3.3.3斷裂鏈結類型:(u.State, v.State)=(VB, VB) 27
3.4複雜度分析 32
第四章 模擬結果與討論
4.1 模擬工具介紹 33
4.2比較的其他方法 36
4.3 量測指標 37
4.4 模擬環境 38
4.5 數據分析與討論 39
第五章 結論 46
參考文獻 47

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