在此論文中，我們首先針對Directional Broadcast (DIB)協定於行車隨意網路推導因超出傳輸範圍而失敗的機率，並在其中並探討傳送端與接收端相對速度對其之影響。然而，我們提出Enhanced Directional Broadcast (EDIB)協定，此協定修改原DIB協定Request-To-Broadcast (RTB)/Clear-To-Broadcast (CTB)之交握機制以降低傳輸失敗機率。EDIB協定選擇中繼點過程中，將可能於傳輸緊急訊息過程中而因超出傳輸範圍而失敗的車子排除在外，以提高轉傳的可靠度。此外，若於RTB/CTB交過過程中CTB訊息發生碰撞，我們利用Distance Defer Transmission (DDT)之方法選擇出距離造成CTB訊息碰撞車子最近的鄰近車輛進行重新傳送RTB訊息，如此可以縮短傳輸距離，以增快RTB/CTB交握過程之時間花費。最後，我們也設計出一模擬器以量測DIB協定與EDIB協定於行車隨意網路之效能表現，雖然EDIB協定需要花費較多的轉傳次數，但在傳輸失敗率、傳輸時間及選擇中繼點之時間花費，EDIB協定比DIB協定表現傑出。

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