# Path Loss Measurements and Model Analysis in an Indoor Corridor Environment at 28 GHz and 38 GHz
## 3 Path Loss Measurements and Models
### NLOS Measurement Evaluation: Study Results and Discussion
However, in the case of V-H polarizations, as seen in Figure 21, it almost follows the same pattern as the V-V situation, but with a slight difference in the value of the path loss in the frequency bands. This still justifies the fact that the path loss will always be greater at higher frequencies. Figure 20 demonstrates improved sensitivity. The path loss in the 38 GHz band was higher in the FI cases of Figure 22, as expected. However, there was a case where the value was similar when the distance between the Tx and the Rx was 10 m. Figure 23 depicts the same situation, but with a higher path loss value for the two frequencies. At a distance of 10 m, the path loss values also coincided. Tables 3 and 4 display the parameters of the CI and FI path loss models for both polarizations for the NLOS and LOS, respectively. Figures 20-23 show comparisons of the CI and FI plots for the 28 and 38 GHz frequency bands. Figure 19: Path loss versus distance at 38 GHz for the NLOS scenario and V–H polarization. Taking a look at the overall measurement results in the LOS and NLOS, both models clearly fit the measured path losses and produce comparable results in both antenna polarizations. The PLE was also much higher in the V-H polarization of the NLOS scenarios due to signal degradation along the path from Tx to Rx. At 38 GHz, the highest value was 3.33 (V-H). This demonstrates that reflections from dry concrete and bricks become more difficult at this frequency when compared to other frequencies. This was due to the lack of direct bore sight between the Tx and Rx antennas. The Rx (as it transmits through the path from the Tx antenna) only relies on signal diffractions and reflections from obstacles. Furthermore, the values of \(\sigma_{min}^{Cl}\) and \(\alpha_{FI}\) increase to a peak at 28 GHz, rather than 38 GHz, in the NLOS scenario. This demonstrates that both antenna polarizations have better signal performances at 38 GHz. The slope of the path loss curve was roughly the same as the PLE values in both LOS and NLOS situations. This means they behaved  
Figure 21: CI path loss versus distance at 28 and 38 GHz for the NLOS scenario and V–H polarization. Figure 20: CI path loss versus distance at 28 and 38 GHz for the NLOS scenario and V–V polarization. similar in this environment. In the NLOS scenario, the minimum standard deviation values were much higher. This is due to the richness of the reflections and diffractions, which allowed for constructive inference of the multiple signal components reached on the Rx side, particularly in the 38 GHz V-V polarization. The NLOS scenario's general behavior, which was characterized by a higher path loss, was caused by the diffraction effect, which disrupted signal transmissions. Because the Tx and Rx are not in the bore sight, obstructions between them tend to interfere with the signal transmission. Some obstacles reflect signals at specific frequencies, while others simply absorb and garble them. However, in either case, they degrade the signals, especially when the power budget is limited. The electrical properties of the material causing the obstruction also have significant impacts on the signal. Some are excellent conductors, while others are excellent insulators. Figure 23: FI path loss versus distance at 28 and 38 GHz for the NLOS scenario and V-H polarization. Figure 22: FI path loss versus distance at 28 and 38 GHz for the NLOS scenario and V-V polarization. G Wireless Network Comparison of the Obtained Propagation Parameters with Other Indoor mmWave Outcomes  
The propagation variable values are listed in a range in Table 5 (lower--upper). This is due to the fact that the work was conducted under a variety of LOS and NLOS conditions. Due to the accumulation of many path components, the lower range of PLE in this work under the LOS scenario was 2.23 at 28 GHz V-V. In the 73 GHz frequency range for V-H antenna polarization, the authors of [39] found the greatest PLE for an indoor environment with the measuring campaign conducted in a sizable open hall.