隨著無線通訊網路技術的進步，使得無線網路可以提供與有線網路等同的資訊服務，加上電子元件價格漸漸下降，以及行車安全日益受到重視，車用隨意無線網路(Vehicle Ad-hoc Network) 漸漸受到各界的重視，並成為重要的研究議題。
在過去的研究中，大多將路由分成proactive、reactive及Hybrid三類，但是，這些方法都是連線導向的，也就是在傳輸之前須建立傳輸路徑，路徑的維護及修復所造成的負擔會導致網路效能下降。因此position based路由被提出來解決以上三類的缺點。position based路由利用節點的位置來做為路由考量的依據，因此不需要建立或維護任何路徑，但需要知道目標點的位置。大部分的方法都假設目標點是在固定已知的位置，或是可以透過位置服務來取得目標點的位置，但是，假設目標點固定在車輛網路中是不合理的，使用位置服務則會產生額外的網路負擔。同時，目前提出的position based路由並沒有依據車輛移動的道路環境動態選擇不同路由策略的方法。
有鑑於此，本文提出支援可適性路由的協同式目標尋找方法(COoperation Destination discovery Scheme with ADaptive routing, 縮寫為CODS-AD)來解決以上所提及position based路由的缺點。此方法主要分成兩部分，可適性路由 (Adaptive Routing) 依據道路環境的車流量動態調整路由策略來提升封包的傳達率並減少頻寬的浪費。協同式目標尋找方法(CODS)則透過網路節點合作的方式調整傳輸路徑，降低目前已提出的方法中路徑維護造成的網路負擔。
最後，我們透過TraNS以及NS2來模擬真實情況車輛移動所組成的無線網路環境來驗證此機制的效能。經由模擬結果我們能證明此機制的正確性與可行性，透過CODS-AD，我們成功減少了更新位置服務造成的網路負擔，並同時提升封包的到達率。相信此適應性路由機制及協同式目標尋找機制能為車用隨意無線網路上的封包傳輸提供新的方向與做法。

With the advances in wireless network technology, the wireless networks can provide the same information service that provided by wired networks. Prices of electronic components decreased gradually, and traffic safety has received more and more attentions. Vehicle Ad-hoc Network be realized and expanded as a research area that has received increased attention from the community.
In the past decade, a variety of routing protocols have been proposed. They can be divided into topology based routing protocols and position based routing protocols. The topology based routing protocols are connection-oriented and the maintenance and restoration of transmission path decrease the network performance. The position based routing protocols need the position information of destination node. Most of researches assume that there are location services or the destination node is a fixed node. However, location service will cause high control overhead and the assumption of fixed node is unrealistic. In addition, existing position based routing protocols do not adapt its forwarding strategy according to the environment information. This will cause bad next-hop node selection.
Therefore, this thesis proposes a novel routing protocol, COoperative Destination discovery Scheme with ADaptive routing (CODS-AD). CODS-AD is divided into two parts, adaptive routing and CODS. With adaptive routing, it can dynamically change the forwarding strategy according to the traffic density of road segment to reduce unnecessary waste of bandwidth and increase the delivery ratio. Furthermore, the CODS-AD can find the position of destination node without the support of location service and modify the transmission path dynamically. Therefore, CODS-AD decreases the control overhead caused by periodic update messages that are used to update location services and path maintenance. Finally, we use TraNS and NS2 to simulate the real vehicle mobility and wireless transmission. The proposed scheme, CODS-AD, can decrease the control overhead and achieves high delivery ratio.

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