雙階層交通資訊網路中的適應性路由機制

Abstract

近年來智慧型運輸系統的研究逐漸受到重視，而智慧型運輸系統中的重要服務之一為提供即時的交通資訊。為了降低即時交通資訊系統的建置成本以及提高系統可靠度，分散式的系統例如以車間隨意通訊網路(Vehicular Ad-Hoc Network)或是點對點網路(Peer-to-Peer Network)為主的交通資訊系統被提出。為了進一步改進交通資訊查詢的成功率以及降低查詢的延遲，近年來的研究提出雙階層交通資訊網路來整合車間隨意通訊網路以及點對點網路。 然而，由於交通資訊查詢被同時廣播到雙階層網路中而導致重複的查詢封包，進而產生額外不必要的系統流量及負擔。 本論文提出一個適用於雙階層交通資訊網路中的適應性路由機制以提升交通資訊查詢的效率。實驗結果顯示提出的適應性路由機制可在維持相同的系統查詢成功率之情況下，有效降低系統不必要的流量並同時降低交通資訊查詢的延遲。

Intelligent Transportation Systems (ITSs) have attracted much attention recently. One of the most important services for ITSs is to provide real-time traffic information service. To reduce the deployment cost and achieve high service availability, decentralized approaches such as VANET-based or P2P-based traffic information systems were proposed. To further improve the successful rate of traffic information lookups and lookup latencies, a new two-tier traffic information system which integrates low-tier VANET and high-tier P2P systems has been developed. However, conventional two-tier traffic information system may introduce extra routing overheads since the information lookups are broadcasted over two tier networks and introduce redundant lookup messages. This study proposes an adaptive routing mechanism in two-tier traffic information system to improve the efficiency of traffic information lookup. Simulation results demonstrate that the proposed scheme reduces the lookup latency and overhead while achieving the same lookup successful rates compared with the conventional approach.