以安全、節能及遊憩為目的之車載網路系統---子計畫四：車載通訊網路繞徑技術(I)

Abstract

本計畫主要是在車載通訊網路探討繞徑之問題，近年來隨著網路快速發展，人們 對網路的使用日益增加，因此網路的傳輸隨著需求拓展出許多種類，其中車載通訊網 路便是近來快速興起的傳輸模式。車載通訊網路是無線隨意移動網路的一種，由移動 的汽車所組成並具備了分散性與自組織性。藉由無線通訊與資料傳遞技術，串聯交通 工具以及路邊交通設施而形成的網路，讓所有的用路人可以即時取得與傳遞所需相關 交通及生活的資訊，以便提高行車效率以及增進用路安全與生活的便利性。然而由於 網路中的點可以任意的移動，車載通訊網路拓樸變化的十分迅速，也使得車載通訊網 路屬於高度動態的網路，因此車載通訊網路與傳統探討的無線隨意移動網路有以下三 個不同的問題需要解決。(1)高度動態的網路 -由於車子在高速下行駛，使得連線的 穩定度大大的下降，並且增加了繞徑技術的困難度。(2)網路有不連通的情況 - 可能 使無線網路形成許多不連通的子網路。(3)網路密度分佈很不平均 - 因為交通狀況， 使得車輛疏密程度有很大的差異變化。本計畫的目標將是針對新興的車載通訊網路繞 徑技術所會面臨的上列問題，深入的分析並提出有效的解決方案。

This proposal focuses on the unicast routing technologies for the advanced Vehicular Ad hoc Networks (VANETs). The VANET is a subclass of MANETs, which would perform crucial functions in road safety, detection of traffic accidents and reduction of traffic congestions. VANETs are evolving as one of the practical applications of MANETs in the future. This vehicular network is interconnected with vehicles which have wireless interface. However, VANETs exhibit very different characteristics from MANETs. The main differences between VANET and MANET are: (i) Dynamic Mobility and High Relative Speed – VANET’s mobility pattern must consist with the topology of the road. In general case, the moving speed of the vehicle is up to 60 ~ 130km/hr. And the relative speed of vehicles will be higher, especially when moving in the different direction; (ii) A Fragmented Network – A frequent fragmentation of the network will significantly degrade the performance of routing protocols; (iii) Different Network Density – Depend on the traffic pattern, the density of vehicles varies a lot in different areas. The goal of this proposal is to develop the unicast routing solutions to deal with the above issues faced by the VANETs.