## 4 Simulation Results
### Received Power
In outdoor wireless communications, estimating path losses is a relevant modeling parameter [70]. Signal transmission using the mmWave bands is related to substantial penetration losses by objects that usually do not cause such a sharp effect at frequencies below 6 GHz. Figures 12 and 13 show the Path Loss for the simulated scenarios, considering the interposition between the transceivers of two vehicles of different sizes. Radials in the direction of the line-of-sight (LOS) corresponding to a Path Loss Area (PLA) represented in Figure 11 were used, taking into account the dimensions of the obstruction by the bus as the maximum area aperture. For this area of 17 degrees wide, one path per degree is taken, and the mean path loss exponent (\(\overline{PLE}\)) and mean shadow fading (\(\overline{\sigma_{SF}}\)) is estimated. For both objects, the distance between the transmitter and the obstruction is approximately 17 m, considering the points before this distance as LOS points. The model that is used to adjust the path loss from the simulation results is the CI free-space model with the advantage that within its parameters, there is a frequency dependence. The equation for estimating path losses through the CI model is [69]:  
\[PL_{CI}(f,d)[dB]=FSPL(f,d(1m))[dB]+10n\log(d)+\sigma_{SF} \tag{3}\]  
where \(FSPL(f,d(1m))=20\log\frac{4\pi f}{c}\) denotes the free-space path loss in dB at a Transmitter-Receiver (TR) separation distance of 1 m at the carrier frequency \(f\); \(c\) is the speed of light, \(n\) is the path loss exponent (PLE), d is the 3D separation distance between the transmitter and the receiver, and \(\sigma_{SF}\) is the shadow fading standard deviation for large-scale signal fluctuations. The average fit of the results  
Figure 12: Path Loss (dB) with a car obstruction in a 17-degree area (PLA) and the mean \(\overline{PLE}\) estimation for a CI free-space model. Figure 13: Path Loss (dB) with a bus obstruction in a 17-degree area (PLA) and the mean \(\overline{PLE}\) estimation for a CI free-space model. collected in the simulation to the CI free-space model is given in Figures 12 and 13. A \(\overline{PLE}\) of 2.11 and a \(\overline{\sigma_{SF}}\) of 11.09 dB is obtained for the regular vehicle obstruction and a \(\overline{PLE}\) of 2.84 and a \(\overline{\sigma_{SF}}\) of 15.69 dB for a large dimensions vehicle obstruction (bus). Table 3 incorporates the \(\overline{PLE}\) values and \(\overline{\sigma_{SF}}\) of the simulated data for its fit to the CI free-space model, into a summarize simulation results table. Obstruction by small and large vehicles have been considered in recent investigations, reporting losses between 8.2 dB and 17 dB due to the blocking by large vehicles, adding an average loss of 6 dB on top of a small blocker losses and maximum average large blocker loss of 17 dB [71]. In the simulations, received powers of \(-\)36.21 and \(-\)41.27 dBm are obtained for the scene with directional radiation patterns, in cases of small vehicle and large vehicle obstruction, respectively. These results represent an addition in the path losses of a long vehicle over a small one of approximately 5 dB. In the case of the omnidirectional pattern, the power received at the target is \(-\)72 dBm and \(-\)85.04 dBm for the small vehicle and the bus respectively, corresponding to a higher 13 dB loss in the case of the bus obstruction. As a result, according to the simulation results, the difference in path loss that a large obstacle overlaps over a small one ranges between 5 and 13 dB, which have a good agreement with observations made in the literature [71].