Cognitive cars: constructing a cognitive playground for VANET research testbeds

Simulation today plays a key role in the study and understanding of extremely complex systems, which range from transportation networks to virus spread, and include large-scale vehicular ad hoc networks (VANETs). Regarding VANET scenarios, until very recently, simulation has represented the only tool with which it was possible to estimate and compare the performances of different communication protocols. In fact, it was not possible to thoroughly test on the road any VANET-based multi-hop communication system, as no highly dense vehicular testbed exists to this date. This situation has recently changed, with the introduction of a new COGNITIVE approach to VANET systems research, where it has been shown that it is possible to perform realistic experiments using only a few real vehicular resources (i.e., only a few vehicles that are equipped with wireless communication interfaces). Now, the scope of this paper is to show that it is possible to move further ahead along this recently drawn path, utilizing the features provided by cognitive network technologies. In particular, we will show that cognitive interfaces can play a role as an additional tunable dimension to be used within an experimental platform where highly dense vehicular testbeds can be structured, even in the presence of a few real vehicular resources. The advantage is twofold: (a) they can be used to test new strategies for dealing with the scarcity of spectrum in a very dynamic environment as the vehicular one is, and, (b) they can be used to test the performances of VANET protocols as a function of different frequencies and interface switching delays. As an example of how this can be done, we will provide preliminary results from a set of experiments that have been performed with a highway accident warning system and with a cognitive network based on the Microsoft Software Radio (SORA) technology.