# Path Loss Model for Outdoor Parking Environments at 28 GHz and 38 GHz for 5G Wireless Networks
## 7 Conclusions  
In this paper, large-scale propagation measurement was carried out in a parking lot to study the path loss for 5G over the 28 GHz and 38 GHz candidate bands. These two different frequencies bands were studied in terms of signal losses across different modeled scenarios in a fully pack parking lots. For the single frequency path loss model, the CI-PLEs were approximately identical in the 28 GHz and 38 GHz bands for a single and dual parking lot. The PLE of the 38 GHz band was larger than the 28 GHz by only 1 dB/decade and 3 dB/decade for SPL and DPL, respectively. The FI model showed a tight reflection frequency dependency at 28 GHz and 38 GHz. The 28 GHz slope line value was larger than the slope line at 38 GHz. It represents the wavelength effect, since, as the wavelength was smaller at 38 GHz, the reflection was larger. Thus, the FI model is recommended to be used as a model when considering DPL environments; the recommended frequency is 38 GHz. For the PLM proposed model, the compensation factor for the 28 GHz band was 10.6 dB and 23.1 dB for single and dual parking lot, respectively. This indicates that the power decay for the double-parking lot was twice as large as that of the single parking lot at a 28 GHz band. Figure 11: Predicted received power at 38 GHz. \begin{table}
\begin{tabular}{c c c c c c} \hline
**Tx-Rx Separation** & **Path Loss** & **Frequency** & **Scenarios** & **Power Received (P\({}_{\textbf{r}}\)) (dBm) = P\({}_{\textbf{r}}\)-PL** \\
**Distance (m)** & **Models** & **(GHz)** & & & \\ \hline \multirow{4}{*}{60, 70, 80, 90, 100} & \multirow{4}{*}{CI} & \multirow{4}{*}{28} & SPL & \(-84.4,\)\(-86.2,\)\(-87.8,\)\(-89.2,\)\(-90.4\) \\  & & & DPL & \(-96.9,\)\(-99.1,\)\(-101.11,\)\(-1028,\)\(-104.4\) \\  & & & SPL & \(-88.8,\)\(-90.7,\)\(-92.3,\)\(-93.7,\)\(-95.0\) \\  & & & DPL & \(-94.12,\)\(-96.2,\)\(-98.0,\)\(-99.6,\)\(-101.0\) \\ \hline \multirow{4}{*}{60, 70, 80, 90, 100} & \multirow{4}{*}{FI} & \multirow{4}{*}{28} & SPL & \(-85.1,\)\(-87.2,\)\(-88.9,\)\(-90.4,\)\(-91.9\) \\  & & & DPL & \(-92.2,\)\(-92.8,\)\(-93.2,\)\(-93.6,\)\(-94\) \\  & & & SPL & \(-89.4,\)\(-91.3,\)\(-92.9,\)\(-94.3,\)\(-95.6\) \\  & & & DPL & \(-90.6,\)\(-90.9,\)\(-91.1,\)\(-91.3,\)\(-91.5\) \\ \hline \multirow{4}{*}{60, 70, 80, 90, 100} & \multirow{4}{*}{PLM} & \multirow{4}{*}{28} & SPL & \(-82.6,\)\(-83.9,\)\(-85.1,\)\(-86.1,\)\(-87\) \\  & & & DPL & \(-95.1,\)\(-96.4,\)\(-97.6,\)\(-98.6,\)\(-99.5\) \\ \cline{1-1}  & & & SPL & \(-87.7,\)\(-89.9,\)\(-92.0,\)\(-91.2,\)\(-92.1\) \\ \cline{1-1}  & & & DPL & \(-93.7,\)\(-95.,\)\(-96.2,\)\(-97.2,\)\(-98.1\) \\ \hline \multirow{4}{*}{60, 70, 80, 90, 100} & \multirow{4}{*}{ABG} & \multirow{4}{*}{28} & SPL & \(-94.\)\(-85.9,\)\(-87.6,\)\(-89.1,\)\(-90.4\) \\  & & & DPL & \(-119.5,\)\(-119.9,\)\(-120.2,\)\(-120.5,\)\(-120.8\) \\ \cline{1-1}  & & & SPL & \(-89.0,\)\(-90.9,\)\(-92.6,\)\(-94.1,\)\(-95.4\) \\ \cline{1-1}  & & & DPL & \(-120.7,\)\(-121.1,\)\(-121.4,\)\(-121.7,\)\(-122\) \\ \hline \end{tabular}
\end{table} 
Table 5: Received power at different transmitter (Tx)-receiver (Rx) separation distance using all studied path loss models. It can be concluded that for the 38 GHz band, the effect of the double-parking lot was less, whereas the power decay was 6 dB in the single parking lot. This shows that the reflection is better and there is a very small shadow effect at 38 GHz when compared to the 28 GHz frequency band. The standard deviation values also showed that the effects at the 38 GHz band were half of those at the 28 GHz band. This work investigated the path loss in parking lots at 28 GHz and 38 GHz. For this study, the narrowband system was used to conduct the measurement. It is powerful system for the path loss models, as the total power concentrate at the center frequency. However, the delay spread and angular spread cannot be detected. For future work, the wideband channel sounder will be used within a 1  GHz bandwidth, where the delay and angular spreads can be extracted from multipath components.