Appropriate selection of urban vehicle-to-vehicle radio propagation models

Urban vehicle-to-vehicle radio propagation is commonly modeled using simplified path loss models which are either based on empirical measurements or analytical considerations. These models have in common that their parameterability is rather limited and it is thus only possible to consider, e.g., the distance between transmitter and receiver, antenna heights or street widths. Aspects, such as the shape of an intersection or to which degree vehicles or vegetation are present cannot explicitly be considered using these models. In contrast, recent work suggests that even effects, such as obstructed line-of-sight by vehicles on the road or destructive multipath propagation can drastically influence simulation results. Accordingly, adjusted models are suggested which, however, incorporate only one additional aspect at a time. In this paper, we pursue a different approach and take a first step in evaluating which aspects influence radio conditions in urban areas to which degree and how these individual aspects affect each other. We consequently consolidate existing works and evaluate in which situations a more detailed radio propagation modeling might yield substantially different results with respect to the requirements of IEEE 802.11p networks. In order to achieve comparable results and being able to model several aspects, we employed ray tracing with an accurate geographic scenario and individually modeled obstacles, such as post boxes or trees at the roadside. Our results show and explain that the presence of radio obstacles can indeed make a difference within certain ranges if considered individually, the overall path loss in a heterogeneous and crowded urban scenario, however, is still approximated well with currently employed path loss models.