Information in motion: road vehicles as wireless relay stations for an ad hoc communications network

Abstract

There is growing interest among automobile engineers and wireless communications researchers in the concept of a Vehicular Ad-hoc NETwork (VANET). Each motor vehicle on the road today provides a natural platform for mobile communications. When equipped with suitable on-board device, the population of vehicles in a busy area becomes a wireless network capable of relaying signals across considerable distances, without the need for a central transmitter.

Among the applications so far suggested are the propagation of safety warnings such as icy road conditions, crime prevention, surveillance aimed at public security, together with less urgent passenger services, and even congestion management. To determine whether and how such a system would function, it is necessary to model two distinct kinds of network simultaneously—the road system and the wireless network. The challenge is signi-cant, not least because of the many factors involved. The authors have adapted a cellular automaton (CA) approach, which is used to investigate the relationship between communication, contention/interference and mobility. The results show how mobility a-ects network performance and how the processing gain G can be used to design e-ective coverage areas which maximize the total network throughput. Most important for safety-critical applications, a VANET can break down under congested road traffic conditions because of radio interference among the vehicles.