異質網路環境之行動搜尋關鍵技術-子計畫一---車用隨意網路存取控制與連結機制之研究

Abstract

隨著無線通訊網路技術的進步，加上電子元件價格漸漸下降以及行車安全問題越來越受重視，各國政府紛紛投入智慧型運輸系統(Intelligent Transport Systems, ITS)的研究。車用隨意網路(Vehicle Ad-hoc Network, VANET)，為當前了為實現ITS所發展出的重要網路架構。在個架構下，每一個搭載無線通訊設備的車輛，都可以透過路旁的路側系統(Road Side Unit, RSU) 連線到Server 端索取所需的資訊。而當車輛距離基地台太遠超出傳訊範圍時，也可透過其它的車輛幫忙轉送。換句話說，每一個車輛都可視為是一部行動無線路由器(mobile wireless router)。因此，這樣的架構可大幅提升網路建置彈性，只要有車輛的地方，即可是VANET的涵蓋範圍。 子計畫一的主要研究目標在於發展VANET網路之存取控制協定(Media Access Control, MAC)及連結機制(Connectivity Support)。分為三個階段:在第一年的計畫中，先針對網路低層的MAC進行設計，我們將基於未來最有可能被廣泛使用的專用短距離通通訊(Dedicated Short Range Communication , DSRC)標準進行發展，以合乎趨勢的走向。接下來，在第二年的研究裡，我們將為高速移動的車輛設計以有效的叢集化及功率指定方法，以減少網路干擾，進而提升流量產出及管理上的效果。基於這些低層的技術及規劃方法後，最後一年，我們將發展上層的路由及配送方法，以可克服VANET網路因高度移動和短距離傳輸所造成間歇性連結特性及其衍伸的延遲問題，達到可靠傳輸的最終目標。總括而言，我們將在三年中階段逐步完成下列三大主題:

Due to the dramatic cost down on electronic components and the advances on wireless technologies, the development of Intelligent Transportation System (ITS) has drawn intensive attention in recent years from many countries. The Vehicular Ad hoc Network (VANET) is a promising approach for the future ITS. In this novel network architecture, a communication is either enable between the vehicle and road side unit (RSU) or between any two cars in multihop fashion. In other words, the deployment is flexible and the network coverage can be easily extended to wild range. In this subproject, we intend to develop Media Access Control (MAC) and connectivity mechanisms to support the VANET. It is a three-year project: In the first year, we will design the MAC protocols based on the Dedicated Short Range Communication (DSRC) standard, which is expected to be wildly used in the near future. In the second year, the design issue on clustering and power assignment will be investigated for very high speed vehicle. Based on these grounds, in the last year, we will propose the carry and forward protocols to overcome the long latency due to the intermittent connectivity in vehicular networks. Our research goal for each year is summarized as follows: