Wireless access technologies for vehicular network safety applications

Road safety is becoming urgent due to a large number of traffic accidents each year and its severe socio-economic impact on a global scale. A promising solution to improve road safety is to deploy VANETs, a technology that can make driving safer by enabling a variety of advanced road safety applications, through broadcasting of safety messages by vehicles and roadside units. This article discusses the ability of existing wireless technologies to provide reliable broadcast of safety messages, which are necessary to realize any road safety application. The wireless technologies under consideration are the IEEE 802.11p standard, the current cellular network standards, and a time-division multiple access protocol, known as VeMAC, recently proposed for VANET safety applications. The performance of the IEEE 802.11p standard is compared with that of the VeMAC protocol via computer simulations in different highway and city scenarios, including a traffic bottleneck situation caused by emergency parking of a vehicle on a highway. We also review recent developments of the VeMAC protocol, including prototype experiments and on-road demonstrations of VeMAC-based safety applications implemented in real cars.