A simulation framework for traffic information dissemination in ubiquitous vehicular ad hoc networks

Abstract

The ongoing efforts to apply advanced technologies to help solve transportation problems advanced the growing trend of integrating mobile wireless communications into transportation systems. In particular, vehicular ad hoc networks (VANETs) allow vehicles to constitute a decentralized traffic information system on roadways and to share their own information. This research focused on the development of an integrated transportation and communication simulation framework to build a more realistic environment with which to study VANETs, as compared to previous studies. This research implemented a VANET-based information model into an integrated transportation and communication simulation framework in which these independent simulation tools were tightly coupled and finely synchronized. A traffic information system as a VANET application was built and demonstrated based on the simulation framework developed in this research. In this system, vehicles record their own travel time data, share these data via an ad hoc network, and reroute at split sections based on stored travel time data. Disseminated speeds of traffic information via broadcast on a real roadway network were obtained. In this research, Traffic information speeds were approximately between the road speed limit in a low traffic density - in which case they were mostly delivered by vehicles traveling on the opposite directions - and half of the transmission range (250/2 meter) per second in a high traffic density, which means they were delivered by vehicles traveling in the same direction. Successful dynamic routing based on stored travel time data was demonstrated with and without an incident in this framework. At the both cases, the benefits from dynamic routing were shown even in the low market penetration. It is believed that a wide range of VANET applications can be designed and assessed using methodologies influenced by and contributed to by the simulation framework and other methods developed in this dissertation.