在過往研究中，為提升基礎設施運用車間通訊網路(Vehicular Ad hoc Networks; VANETs)傳送到訊息到車輛的效率，有提出利用目標車輛行車路徑預測車輛可能的訊息會合點，以增進傳送成功率的方法。然而，這些方法並沒有去考慮行車環境對車輛的影響，以及會合點彼此之間的地緣關係。更甚者，當車輛發生繞路事件時，這些研究也無法針對此類事件做出相對應的處理。因此，我們在這篇論文提出兩個方法－eTGMD和tc-eTGMD，來解決上述問題。eTGMD 設計主要是在忽略繞路事件所造成的影響下，希望以最少的封包去完成群組車輛的訊息傳遞。其主要設計原理是去探索群組內車輛的未來行車路徑，找出幾個適切的訊息會合點，再利用群播樹(multicast tree)將訊息傳至這些會合點，待群組車輛經過時接收。具體而言，eTGMD運用迭代法，在每回合使用貪婪演算法去找出能以最少封包量服務最多車輛的點，再把選出的會合點加入群播樹。為驗證其效能，我們針對eTGMD利用數學模型分析執行效能及執行時間，亦提出電腦模擬模型來研究所設計之協定的效能。第二個方法tc-eTGMD則是致力於當繞路事件對傳輸效能造成影響時，提供一個有效率的解法，以維持傳送成功率。其主要設計原理是試圖去降低處理繞路事件時兩個必要的程序─繞路通知、以及路徑再規劃─所消耗的網路資源。具體而言，我們將運作環境切成若干個小型的區塊，並在各區塊中找出伺服的代理人協助處理繞路事件，以減低每次的處理時間以及伺服器的運算資源。為了因應分區的路徑建立議題，我們亦提出相對應的階層式建樹協定。為驗證tc-eTGMD的效能，我們提出電腦模擬模型來研究繞路事件帶來的效能影響以及所設計之協定的效能。

In the literature, future vehicle trajectories have been exploited to improve the performance of challenging infrastructure-to-vehicle (I2V) group message delivery over vehicular ad hoc networks. However, most of these researches separately handles the rendezvous point selection and the multicast tree construction, results in significantly restricting the overall message delivery performance. Moreover, they do not consider that the destination vehicles make take unexpected detours. To resolve these issues, this dissertation designs a series of trajectory-based I2V group message delivery protocol, eTGMD and tc-eTGMD, for delay-tolerant vehicular applications. The first work, eTGMD, applies for low/non-detour-event environment. The goal of eTGMD is to minimize the overall transmission cost under the premise that the delay constraint is guaranteed. It is achieved by iteratively selecting a promising rendezvous point and extending the current multicast tree to cover the selected rendezvous point. The second work, tc-eTGMD, designs for high-detour event environment. The objective of tc-eTGMD is to design a I2V group message delivery protocol which can handle the detour events with the lowest required overhead. Specifically, when member vehicles take detours, rather than rebuilding the whole tree, tc-eTGMD tries to only redeploy the routes to the detour vehicles. Theoretical analysis and simulation results show the effectiveness of the proposed trajectory-based I2V group message protocols in computational complexity, packet delivery ratio, and the transmission overhead.

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