應用於車載隨意網路環境下以移動式閘道器為基礎之路由協定

Abstract

近幾年來車載隨意網路(Vehicular Ad Hoc NETwork, VANET)的相關研究越來越受重視，已成為炙手可熱的研究議題。在設計車間(vehicle-to-vehicle, V2V)通訊的路由協定上，必須考量到有時因車輛移動的速度變化太快，而造成通訊中斷的狀況。然而利用車輛對基礎建設網路(vehicle-to-infrastructure, V2I)的溝通可以大幅改善以上的問題。在此篇論文中，我們提出一個路由協定名為MGRP(Mobile-Gateway Routing Protocol)協定，MGRP協定結合了V2V和V2I兩者的通訊方式，在系統中，所有的車輛都具備有802.11的通訊介面，此外，部分的車輛另具備3G的介面，這些車輛稱為移動式閘道器。而移動式閘道器可透過IEEE 802.11介面接收一般車輛的封包，再利用3G介面將封包經由基地台送至閘道器控制中心。而閘道器控制中心會依據目的地車輛的位置，尋找目的地周邊的移動式閘道器，並將封包轉送給這些移動式閘道器，透過移動式閘道器以廣播的方式將封包送至目的地車輛。實驗結果顯示，我們提出的MGRP比起傳統的GPSR(Greedy Perimeter Stateless Routing for Wireless Networks)協定明顯提升封包傳送率以及縮短整體路徑。

Development of vehicular ad hoc networks (VANETs) has drawn intensive attention in recent years. Designing routing protocols for vehicle-to-vehicle (V2V) communication in VANET may suffer from frequent link change and disconnection. Vehicle-to-infrastructure (V2I) communication can overcome the challenge by relaying packets through the backbone network, but is limited to those areas where a RSU exists. In this thesis, we present a position-based routing protocol, named mobile-gateway routing protocol (MGRP), for VANETs. The MGRP combines V2V and V2I communications, and utilizes a part of vehicles as mobile gateways. Each mobile gateway connects with a base station through a 3G interface and communicates with other vehicles without the 3G interface through an IEEE 802.11 interface. Upon received packets from a vehicle, the mobile gateway forwards the packets to a gateway controller via the base station. The gateway controller then searches the position of the destination vehicle and determines a set of gateway vehicles close by the destination to forward the packets. Simulation results show that the MGRP can significantly improve the packet delivery ratios and reduce the transmission hop count.