近年來無線傳輸技術的發展日趨成熟，無線網路已經被廣泛的應用於日常生活中。由於交通蓬勃的發展，道路易造成車輛壅塞，甚至發生交通意外事件，為了降低緊急事件擴大的情形，如何在車載隨機網路中設計多躍散佈緊急訊息封包的廣播協定為目前炙手可熱的研究議題。然後緊急訊息的傳輸需要可靠且快速的傳輸方式，為了能將緊急封包傳輸到指定區域，如何減少傳輸時的碰撞與所需的時間是困難的挑戰。因此在本篇論文中，主要探討在車載隨意網路下，利用方向性天線之特性使傳輸車輛能夠快速蒐集鄰居車輛訊號強度資訊，並藉由訊號強度分析找出最遠車輛所存在之位置。以進行多躍散佈緊急訊息封包廣播，減少多躍散佈所耗費之時間，並且能夠有效的找出代傳車輛。最後透過模擬分析，本篇論文所提出之廣播協定，在多躍散佈所耗費之時間以及有效找尋代傳車輛方面，有顯著的改善。 Recently, wireless communications have been used in the daily life with the growth of the wireless networks, such as vehicular ad hoc networks. The rapid development of transport increases the congestion and traffic accident. Therefore, many countries develop the intelligent transportation system and subsystem, dedicated short range communication technology to apply on the vehicular ad hoc networks for the communications among vehicles in the high mobile environments. The main purpose of the vehicular ad hoc networks is to provide the emergency message dissemination and normal data transmissions. In order to keeps drivers far away the traffic accident, the broadcast of immediate emergent notifications in vehicular ad hoc networks has become one of the hot research issues. Therefore, this thesis proposes a reliable emergent notifications broadcast protocol using directional antennas in vehicular ad hoc networks. The proposed protocol assigns the forwarding vehicle based on the neighboring vehicular information. Therefore, the protocol not only provides a broadcast of the reliable emergent notifications, but also shorts the wasted time used for the assignment of the forwarding vehicle and the collection of neighboring vehicular information.
