On the Necessity of Three-Dimensional Considerations in Vehicular Network Simulation

Despite significant improvements concerning the level of realism in Vehicular Ad hoc Network (VANET) simulation, the effects of three-dimensional aspects are still neglected by the majority of packet-based simulation tools. In most of the cases, a planar projection of the road network in question is assumed, leading to a misrepresentation of scenarios including bridges, hilly terrain or elevated infrastructure. In this paper we show that the consideration of three-dimensionality in realistic scenarios can lead to significantly differing results compared to 2D-only simulations. We discuss the requirements and extensions which are necessary in order to provide a three-dimensional simulation environment. This includes the support for three-dimensional antenna patterns as well as a model covering environmental diffraction effects. We examine the implications of three-dimensional aspects on the results of a city-wide simulation scenario showing that the number of vehicles in reach decreases noticeably. The outcome of a second, more specific use case even indicates that proper functioning of this specific application might be completely compromised, in harsh contrast to the result of the common 2D simulation approach, emphasizing the importance of 3D VANET simulation.