## 3 Materials and Methods
### Scenario Description  
In this section, the real scenario used to model vehicular communication links through the 3D-RL algorithm is described as well as its rendered schematic view used for simulation. Figure 4 presents a collage of photos of the real scenario, located in a side street of Tecnologico de Monterrey, Campus Monterrey, Mexico. As depicted, the modeled fragment corresponds to an area of approximately 150 \(\times\) 68 m with several types of vegetation, such as different trees and shrubbery. The portion corresponding to the avenue occupied by the vehicles has a length of 150 m and a width of 16.5 m, where a median strip with inhomogeneous vegetation and two lanes per driving direction are included, representing a classical urban complex heterogeneous vehicular scenario. Moreover, abundant vegetation, private fences and buildings with one to eight floors are surrounding the delimited segment area.  
This scenario has been chosen for its usefulness in terms of vehicular communication in urban environments. The presence of a median strip with abundant trees constitutes an engaging and challenging scenario for V2V communications between vehicles at different roads. In this sense, two main scenarios have been considered for simulation: first, a car obstruction in the communication link and then, a bus obstruction for the worst case study. Both modeled scenarios with their corresponding communication links analyzed cases are depicted in Figure 5.  
For both scenarios, the transmitter has been placed above the left vehicle colored in yellow (see Figure 5 for reference) located in the road at 1.5 m height. Two different use case setups have been considered for simulation. On the one hand, the first configuration using an omnidirectional antenna emulating a more typical/conventional user case hardware setup with 0 dBi antenna gain and 28 GHz transmission frequency. On the other hand, an steerable antenna has been considered for the second use case setup, which can be associated with more demanding applications, such as law enforcement, ambulances, firefighters or road safety applications, where a quick response and a high demanding performance is required. The steerable antenna characteristics are the following: a beamwidth of 60 degrees, 0 dBi antenna gain and 28 GHz transmission frequency. Furthermore, the in-house 3D-RL tool allows the configuration of a Power Amplifier (PA) and a Low Noise Amplifier (LNA) in the transmitter and/or receiver link side, respectively, according to the different use case setups considered. In Table 2, the summarized simulation parameters are presented.  
Figure 3: Schematic view of the 3D-RL implemented modules with the combination of hybrid techniques to reduce the computational load. Different material properties and propagation phenomena are considered in the different modules based on the frequency under analysis.  
At the same time, for both scenarios, the receiver has been located above the right vehicle colored in yellow (see Figure 5 for reference), on the opposite road lane of the transmitter, at a distance of approximately 26 m. As has been introduced, two different scenarios have been emulated for each use case setup, considering a LOS communication obstruction by a regular car (colored in orange in Figure 5a) or a bus (colored in orange in Figure 5b). The specific characteristics of each blocking object are: the car is 4.6 m long, 1.6 m width and 1.5 m high while the bus is 11 m long, 2.7 m width and 3.45 m high. Finally, it must be remarked that all the realism of the stage has been considered for simulation, from the luminaires locations to the traffic lights, as well as the irregular people traffic, emulating real-case conditions.  
Figure 4: Real scenario collage of photos with considered scatterers as buildings, lamp posts, fences, and vegetation, among others.  
Figure 5: General and detailed view of the simulated 3D scenarios for both case studies: (**a**) V2V communication link with a blocking car, (**b**) V2V communication link with a bus obstruction.