在無線隨意網路中，不管網路中是否有全球定位系統（GPS）的存在，路由協定的設計都是一個重要的議題。在一般的路由協定中，每個節點通常都只可以得知自己和鄰居的座標（真實的或虛擬的）。藉著利用這些座標，節點就可以決定該把封包傳送給哪個鄰居，在我的論文中我希望某些節點還可以知道一些傳輸範圍外的節點座標，利用這些額外的座標可以用來改善路由協定的效能。這種傳輸範圍外的節點就稱之為虛擬鄰居。論文的第一部分是針對可使用真實座標的路由協定（geographic routing protocols）來建立虛擬鄰居，這個虛擬鄰居可以用來改善路由路徑的長度。此外，我還提出了一個利用虛擬鄰居來傳送封包路由協定，這個協定可以跟一些有名的路由協定（GPSR-like routing protocols）做結合。實驗結果顯示，當使用了虛擬鄰居時，幾個較有名的路由協定都可以改善路徑長度，每個節點平均也只需傳送較少量的封包（包含資料封包與建構虛擬鄰居使用的封包）。論文的第二部分則是針對使用虛擬座標的路由協定在存在單向連結的網路上的建構與應用。此部分中使用了虛擬鄰居來處理單向連結，並且指派每個節點虛擬的座標。同時，此部分還提供了一個可利用這些虛擬座標還傳送封包並保證傳輸的路由協定。實驗結果顯示提出的協定可以保證傳輸但是會有較長的路由路徑。

In wireless ad-hoc networks, routing is an important issue regardless of the existence of geographic information. Virtual neighbor is usually used to construct a connection between two nodes each of which is not a neighbor of the other in the network. In this dissertation, I undertake the development of virtual-neighbor-based routing protocols in wireless ad-hoc networks. In the first part of the dissertation, I propose a virtual-neighbor-based scheme capable of augmenting GPSR-like routing protocol to reduce routing path length in wireless ad-hoc networks where each node has the geographic information. I first propose an algorithm to construct the virtual neighbor set (called the progress set for specificity) of each local minimum, such that for any destination at least one progress node is in the progress set or the neighbor set of the node. Subsequently, the ProgressFace algorithm is presented to route a packet based on progress sets during perimeter forwarding. Simulations show that GPSR, GFG, GOAFR+, and GPVFR each conduct a shorter routing path, if augmented with the ProgressFace algorithm. In the second part, since geographic information is obtained with difficulty and a wireless ad-hoc network usually has unidirectional links, I propose a virtual-neighbor-based scheme (ABVCap_Uni) to assign virtual coordinates to nodes that have no geographic information in wireless ad-hoc networks with unidirectional links, and I propose a routing protocol based on the ABVCap Uni virtual coordinates. The proposed routing protocol guarantees packet delivery without computation and storage of global topology features in a discrete domain. Using simulation, I evaluate the performance of the proposed routing protocol (ABVCap_Uni Routing), the greedy landmark-descent routing protocol (GLDR+VLM routing), and the greedy
routing protocol based on geographic information (Euclidean routing). The simulations demonstrate that the proposed routing protocol ensures moderate routing path length cost overhead.

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