## 6 Conclusions  
In this paper, a wireless communications channel in the mmWave frequency band (28 GHz) for vehicular environments is characterized based on the assistance of a 3D-RL software and empirical data. The proposed simulation methodology enables the consideration of full volumetric scenario distribution and the consideration of detailed scatterer distributions, enabling the analysis of scenario  
Figure 17: Measurement results for the opposite sidewalk (\(Pc_{1}\) to \(Pc_{15}\)) and 3D-RL simulation results for these spatial locations. as well as traffic conditions. Two different use cases have been considered: the first one with an omnidirectional antenna for a more typical/conventional user hardware configuration, and the second one using a steerable antenna, which can be associated with high demanding performance applications. For both cases, an V2V link obstruction with vehicles of different sizes (car vs bus) has been analyzed. Results from simulation and measurements have a good match and agree with the statement that vehicular communication in the mmWave frequency band is plausible in ranges from 100 to 200 m.  
It is observed that the inclusion of vehicles of distinctive sizes causes different effects on the channel, showing that the received power at the target is affected approximately between 5 to 13 dB when a large dimension vehicle is between the LOS. In our simulations, a data fit for the CI free-space model exhibits a \(\overline{PLE}\) of 2.11 and a \(\overline{\sigma_{SF}}\) of 11.09 dB for a small dimension obstacle and a \(\overline{PLE}\) of 2.84 and a \(\overline{\sigma_{SF}}\) of 15.69 dB for an obstruction due to a large dimensions vehicle (bus). Other parameters that are affected by the size of the obstruction are the MED and the RMS DS. In the case of the MED, an increase in its nominal value is observed in the simulations with a small obstruction (regular car) with respect to the bus scenarios, this related to the high attenuation that first-order rays receive by the bus obstruction. In the case of RMS DS, there is a decrease in the directional pattern scenarios, an estimation also pointed out in other studies. As a complement to the simulations, a measurement campaign was carried out in the real scenario, where the results of these measurements show an agreement with the 3D-RL simulations. The RMSE of the simulations with respect to the measurement campaign is 2.94 dB, a better fit than the use of a CI model presented in the literature for similar scenarios with an estimated \(PLE\) of \(n=1.98\) and a shadow fading of \(\sigma_{SF}=3.62\) dB [44]. Thus, revealing the close relationship of these parameters with specific scenarios, features that are taken into consideration in deterministic approaches. The RMSE for the measurements performed on the other side of the avenue is 4.05 dB, where the increase in error is related to the different vehicle distributions at every point of the measurements. Future work will be directed to the analysis of this margin for dynamic traffic flow. The proposed methodology can be adapted to consider any variation in terms of network topology, location and configuration of the employed transceivers, characteristics of the surrounding environment or variable node density. [PERSON], [PERSON] and L.A. conducted the simulation and analysis of V2X channel characterization and scenario impact. [PERSON], [PERSON] and F.F. conceived and prepared the wireless communication link design. [PERSON] analyzes the vehicular propagation phenomena. [PERSON] and L.A. prepared the manuscript. All authors have read and agreed to the published version of the manuscript. **Funding:** Project RTI2018-095499-B-C31, funded by Ministerio de Ciencia, Innovacion y Universidades, Gobierno de Espana (MCIU/AEI/FEDER, UE). **Acknowledgments:** The authors would like to acknowledge the support and collaboration of the School of Engineering and Sciences at Tecnologico de Monterrey. **Conflicts of Interest:** The authors declare no conflict of interest.