ABSTRACT
The chapter is organized as follows. The next section highlights the concept of active and passive safety in the domain of automotive safety and exposes the components that aim at protecting passengers before and during a crash.Section 6.3 describes vehicular network architecture and presents main devices that support information exchange within wireless vehicular networks. Then, we exhibit the different types and characteristics of vehicular communications.In Section 6.4, we present the plethora of applications and services supported by vehicular networks. Basically, we describe two types of applications, safety and non safety applications, which have different requirements and delay-critical natures.Section 6.5 is dedicated to studying the various standards that are advocated for vehicular communications. More specifically, communication access for land mobiles (CALM), the car-to-car communication consortium (C2C-CC), and wireless access for vehicular environment (WAVE) are analyzed.Some perspectives and challenges dealing with wireless vehicular network research works are highlighted in Section 6.6. Finally, Section 6.7 presents a general conclusion of this chapter. 6.2 Enhancing Active SafetyThe terms “active” and “passive” are simple but important terms in the world of automotive safety. Active safety is used to refer to the technology assisting in the prevention of a crash and passive safety to components of the vehicle (primarily air bags, seat belts, and the physical structure of the vehicle) that help to protect occupants during a crash.The transport policy goals for road safety set by the European Commission for 2010 can only be reached by means of an integrated and holistic approach through information and communication technology. Research should focus not only on the crash phase and the postcrash phase but also on the precrash phase, taking passive, active, and preventive safety measures into account. Preventive and active safety plays an important role in minimizing collisions risks. For this, new road safety mechanisms have been proposed in the context of vehicular networks.The development and rapid dissemination of safety systems can only be achieved by defining safety functions, integrating in-
vehicle systems, and combining them with enhanced telematics into a wireless vehicular network. In fact, Fig. 6.1 shows that intervehicular communication outperforms cellular communi-cations in the precrash phase. In the postcrash system, passive safety is due to energy absorption measures, emergency calls, rescue systems, and services. Whereas in the precrash system, vehicular communications play a crucial role in warning drivers about future hazardous road conditions, erratic drivers, stop signs, emergency braking, lane changing, forward collisions, intersection collisions, etc.
