Vehicular networks attract a lot of attention in the research world. Novel vehicular applications need a suitable communication channel in order to extend in-vehicle capabilities and, be aware of surrounding events. However, these networks present some peculiarities, such as high mobility or specific topologies. These features affect the performance of applications; hence, more effort should be directed to identify the final necessities of the network. Few works deal with application requirements that should be considered when vehicular services are designed. In this chapter this gap is filled, proposing an analysis of application requirements mapped with suitable communication technologies for physical/MAC and network layers. This study contains key factors that must be taken into account not only at the design stage of the vehicular network, but also when applications are evaluated.
TopBackground
Numerous research works deal with vehicular services, essentially those related to traffic safety, but also traffic efficiency and infotainment are of special importance. However, the achievement of the functional goals of these applications is strongly linked to technological requirements, which vary from one application to another. For instance, safety applications should operate with good location accuracy, and real-time and scalable communications; distributed games or talk applications, however, do not require great scalability or real-time features.
To ensure the appropriate operation of these applications regarding networking, new technological requirements, far away from those identified in fixed networks, appear in vehicular communications. This kind of solutions usually needs to cover many networking necessities for their efficient operation. In this chapter, the most important ones are studied, being identified as: location awareness, geocast capabilities, penetration rate dependency, time awareness, permanent access and mobility.
To meet these demands, a number of communication technologies at access level are currently available. The most important ones are briefly introduced, such as Bluetooth, DSRC (IEEE 802.11p), cellular networks and satellite. Moreover, these technologies are analyzed according to the covered communication paradigms, vehicle to vehicle (V2V), vehicle to infrastructure (V2I) or infrastructure to vehicle (I2V), and the destination nodes involved in the communication (1-to-1 or 1-to-n). In the same way, some of the main network (level-three) technologies studied in standardization bodies of vehicular communications are discussed, in order to determine which of the networking requirements can be covered with them. NEMO [Devarapalli, Wakikawa, Petrescu, & Thubert et al.2005] as well as some common MANET and VANET proposals are briefly described, but also more specialized concepts, like Multihoming [Ernst, Montavont, Wakikawa, Ng, & Kuladinithi et al.2007], Flow distribution [Soliman, Montavont, Fikouras, & Kuladinithi et al.2007, Larsson, Eriksson, Mitsuya, Tasaka, & Kuntz et al.2008], Route Optimization [Ng, Thubert, Watari, & Zhao, et al.2007] and MANEMO, are analyzed. Finally, an overlay architecture using cellular networks shows the feasibility of this technology to enable vehicular communications.