| 摘要: | 在全世界的都會區中，交通擁塞總是一個嚴重的問題，而這問題已經漫延到全部的生活區域，而不再只是限於大都會。在2007年，交通擁塞問題造成了都會區的美國人四十二億小時的浪費和額外28億加侖的燃料的消耗，可以說交通擁擠的問題造成822億美元的損失。且外，它不只是造成了經濟上的損失和空氣的污染，而且它也間接地損害駕駛人的健康和造成不必要的心理壓力。 而隨著汽車和通訊技術的進步，於是發展出智慧性交通運輸系統(ITS)，來解決道路交通的問題，它結合了電子、通信、資訊與感測等技術，以求整合人、路、車輛的管理策略，提供即時的資訊而增進運輸系統的安全性、運輸效率及舒適性，同時減少空氣污染、噪音等對環境的衝擊。而在將來的ITS中，無線車載網路(VANET)是一種被寄以重望的解決方式，它借著在車輛上安裝具有無線通訊能力的裝置OBU(On-board unit)及道路上的硬體設施RSU(Road-side unit)，使得車輛間能夠彼此溝通、交換訊息，並借由和路邊的硬體設置連線達到眾多的應用，如車流量控制、氣候警告、意外回報和網際網路通訊等目的。 考量到交通資訊的即時性及路邊硬體裝置部署有限等問題，分散式系統架構是一個很好的解決方案，分散式系統使用車間通訊的方式來彼此合作並分享交通資訊，進而無需路旁硬體裝置。但車間通訊模式除了必須考慮到無線傳輸的問題，如:封包遺失、頻寬使用、廣播風暴等問題外，還需要考慮到交通及行車資訊本身的特性和交通規模等因素，因此需要針對交通道路、行車資訊和所在環境等因素，發展出一套有效率的交通資訊收集和傳播的機制，並妥善應用所得的資訊，來達到改善道路車輛擁塞的目的。 本篇論文主要是提出了一個精巧及有效的交通訊息收集及傳播機制，並設計了一個分散式交通資訊及車輛路徑規劃系統，能夠大量地節省V2V網路頻寬，近90%;且減少每一車輛的旅行時間大約6%~10%，某些場景下可以到21%，這些模擬結果，可以驗證所提機制在資訊和交通網路上的各項表現，並證明本論文所提出機制的可靠度。Traffic congestion always is a serious problem in urban areas in the world. It is getting worse in regions of all sizes. In 2007, traffic congestion caused urban Americans as many as 4.2 billion hours to travel and to purchase an extra 2.8 billion gallons of fuel for the congestion. Therefore, traffic congestion not only causes economic loss and environment pollution but also damages health of drivers. With the evolution of car and communication technologies, people developed the intelligent transportation system (ITS) to solve traffic problems. The ITS consists of electronics, communications, information and sensing technologies, and integrated management strategy of human, road and vehicle. Researchers study the ITS to provide real-time information and improve transportation system safety, efficiency and comfort, while reducing air pollution and noise impact on the environment. Vehicular ad hoc network (VANET) is a promising approach for future intelligent transportation system. In this research, we take into consideration the use of traffic information and deployment of roadside devices. Although Inter-Vehicle Communication (IVC) is popular adopted in VANET, IVC often suffers the packet loss, broadcast storm, and network bandwidth problems which makes traffic message undelivered or delayed. In addition, data communication in VANET should consider characteristics of traffic and travel information, road scale. For these reasons, we develop an efficient mechanism for information collection and dissemination to reduce bandwidth consumption and improve vehicle congestion. This paper presents a compact and efficient traffic information exchange strategy. It includes information aggregation and dissemination, vehicle routing algorithms and system architecture is designed to simulate proposed mechanism. Moreover, we will examine and verify the contribution of the proposed scheme for data network and traffic road network. These simulation results show that VGED can reduce bandwidth consumption about 90% and 6~10% average travel time and some scenes may be to 21%. These results could support our method strongly. |
