點對點即時路況導航系統

Abstract

隨著道路狀況日益複雜以及車輛日漸普及，為了增加駕駛人行車的便利性，於是就出現了集中式的路況導航系統。此系統雖然能提供即時路況資訊，幫助駕駛人做最佳路徑的選擇，然而卻需要相當昂貴的建置及維護費用。於是有文獻提出了非集中式的路況導航系統，在此系統中，車輛直接透過車間通訊互相交換彼此觀察到的路況，省卻了路況中心的建置費用。然而此系統在交通密度低的情況下路況交換較為困難，車輛要獲得遠距離道路資訊會受到較長時間的延遲。因此我們提出了結合車間通訊及無線網路(WiFi, WiMAX, or 3G)的非集中式點對點路況導航系統。本系統採取了階層式的架構，我們利用點對點網路將車間通訊網路可能離散的部份接起來，讓路況資訊的交換不再受到車間通訊傳輸半徑及車流密度的限制。本系統的目標在於讓駕駛人能夠迅速的獲得正確且即時的道路資訊。在本篇論文的最後，我們會透過實驗數據說明本系統的確能幫助駕駛人作有效率的路況查詢。

Existing centralized real-time traffic information systems provide excellent road guidance. However, the cost for constructing and maintaining the traffic center is expensive. Recently, several decentralized ad-hoc based traffic information systems are proposed. Vehicles in this kind of system detect traffic conditions with GPS devices and exchange observed traffic conditions with each other through inter-vehicle communication. However, ad-hoc based traffic information system has problem to efficiently disseminated traffic condition in large scale places when the penetration rate is low. For this reason, we propose a combined IVC and infrastructure-based decentralized P2P real-time road traffic information system. The system aims at providing accurate traffic reports and supporting efficient traffic report lookup. The system is organized as a two-layer hierarchical architecture. All vehicles participate in the ad-hoc network and broadcast observed traffic condition through IVC. Parts of vehicles are elected as super nodes and they form a P2P overlay atop ad-hoc network to support traffic report lookup through infrastructure-based wireless network interfaces. Simulation results demonstrate that the proposed system dose provide efficient traffic report lookup.