## 4 Simulation Results
### RMS Delay Spread (RMS DS)  
One of the most relevant parameters that describe the temporal dispersion of the multipath channel is the RMS DS, closely related to other important parameters such as the coherence bandwidth. In some studies carried out in vehicular communication for sub 6 GHz frequency bands, it is concluded that when an obstruction occurs, the RMS DS can suffer an increase in values up to 400 ns [74; 75], recently this conclusion has been supported by studies carried out in the mmWave frequencies, concluding that when there is a block in the LOS, an increase in the RMS DS is observed [71].  
Figure 14: Power Delay Profile (dBm) at 1.5 m height: (**a**) Directional radiation antenna pattern and bus obstruction, (**b**) Directional radiation antenna pattern and car obstruction, (**c**) Omnidirectional radiation antenna pattern and bus obstruction, (**d**) Omnidirectional radiation antenna pattern and car obstruction.  
Figure 15 shows a radial (trajectory R2 represented in Figure 11) in the path of the receiving vehicle along the avenue, where the RMS DS values are plotted at each discrete point of the simulation. The X-axis corresponds to the distance in meters from the radial on the avenue. The RMS DS values for these points are plotted in two instances: the upper part corresponds to the values of two simulations, one with obstruction (NLOS) and one without obstruction (LOS). The bottom of each graph corresponds to the calculated difference between the RMS DS values when an obstruction exists and the LOS values. In all the simulated cases, the RMS DS values range from approximately 100 ns to 300 ns with local minima in some cases of 63 ns and maxima of 326 ns.  
Table 3 shows a summary of the RMS DS values in the simulated scenarios, where it can be seen that at the receiver area there is an increase in RMS DS with respect to the simulations without obstructions. In the case of the omnidirectional radiation pattern, there is an increase of 3.24 ns and 21.14 ns for the cases of obstruction by small vehicles and large vehicles, respectively. In the case of communication with the directional antenna, there are increases of 2.16 ns and 3.74 ns respectively, a decrease in the temporal dispersion to its omnidirectional counterpart, especially in the case of obstruction by the bus. It has been reported that the RMS DS decreases with the use of narrow beams, but more measurements in this regard should be considered [71]. Outside the receiver's area, the RMS DS values in some cases exceed 50 ns over the LOS simulation, characterizing the RMS DS variable  
Figure 15: RMS DS simulation results for a radial R2 in the receiver trajectory: (**a**) Directional radiation antenna pattern and bus obstruction, (**b**) Directional radiation antenna pattern and car obstruction, (**c**) Omnidirectional radiation antenna pattern and bus obstruction, (**d**) Omnidirectional radiation antenna pattern and car obstruction.  
with a high dispersion, linked to the type of obstruction that is used. Table 3 shows the variance (\(\sigma_{R1}^{2}\) (RMS DS)) of the difference between the simulations (NLOS-LOS) along R1 trajectory (see Figure 11 for reference). It is worth noting the increase of \(\sigma_{R1}^{2}\) for the cases of obstructions by a large vehicle, closely related to the increase in the number of reflected paths on the bus surface.