近年來隨著車用人口的增多，車間通訊逐漸演變成一項讓許多專家投入研究的熱門議題，尤其是在與封包繞送有關的路由協定上。由於車子高速移動以及其移動時受到道路限制的特性，使過去傳統的無線路由協定無法在車載網路中運作得非常良好。也因此，越來越多研究者把注意力投注在找出適合車載網路的路由協定。然而，目前大多數的車載網路路由協定並未考量到即時的道路狀況，像是車輛數等等。有些路由協定儘管有考慮到當時的道路狀況，卻始終還是有些無法彌補的缺陷，像是運算資源與金錢的耗費。在本篇論文中，我們提出一混合式流量感知地理路由繞送協定(HTAR), 此路由協定使用協同式資訊收集機制有效收集兩種即時交通流量資訊。第一種是道路流量資訊，主要著重在蒐集每條道路的車輛數；而第二種是網路流量資訊，它負責蒐集不同道路的通道負載。接著，HTAR就能夠根據這些已蒐集到的交通流量資訊為即將要傳送的封包計算出可靠且穩定的繞送路徑。此外，在HTAR中，我們提出了一功能性節點，稱作Junc-Tracker。Junc-Tracker不僅要負責蒐集混和式流量資訊外，還要負責決定並散佈最新的道路權重資訊給其他需要這項資訊的節點知道。之後，這些節點才可以根據最新的道路權重計算出最佳路徑。基本上，在每個路口我們都會佈置一個Junc-Tracker。但若使用固定式的裝置去佈置，那成本將會非常之高，所以我們另外又提出了一項機制去降低這項花費，也就是選擇正在道路上行駛的車輛來當我們的Junc-Tracker。在本篇最後的實驗結果顯示出，HTAR不但能夠增進整體的封包傳送成功率，還能夠降低封包被車輛帶著走而無法到達終點的機率。

Recently, as the number of vehicles increase, inter-vehicle communication has attracted many researchers』 interest to investigate, especially in routing protocols. Owing to the high mobility and the road pattern constrains, the traditional wireless routing protocols have difficulties in making robust paths in VANETs. Hence, more and more researches have focused on developing suitable routing protocols for VANETs. However, most of these protocols do not consider the real-time traffic status when determining the routing paths, which results in the high probability of disconnection during data transmission. Although some of them have taken the real-time traffic information into consideration, they still have some problems, such as computing or costing overhead. In this thesis, we propose a routing protocol called Hybrid Traffic Aware Routing (HTAR) which utilizes a cooperative collection scheme to efficiently collect two types of up-to-date traffic information. The first one is road traffic information about the number of nodes on each road and the second one is network traffic information about the channel node of each road. According to the hybrid information, HTAR is able to compute the up-to-date weights to determine the robust routing paths. We also proposed a functional node called Junc-Tracker. The Junc-Trackers are responsible for collecting the traffic information and disseminating the determined weight information to neighbor nodes and adjacent Junc-Trackers. The Junc-Tracker is required to set one at each junction. In order to reduce the cost on setting the Junc-Tracker, we also propose a mechanism about Junc-Tracker selection to decrease the overhead. Simulation results demonstrate that HTAR improves the overall delivery ratio and reduce the probability of carry-and-forward.

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