## 8 Conclusions  
We have described the large-scale path loss in a 5G network for a wideband channel, in a specific indoor to outdoor environment measurement campaign conducted at the UTM-KL campus. We investigated path loss based on the CI and ABG path-loss models for single and multiple frequencies. For all of the measured frequencies, we provided an RMS delay spread, mean excess delay, and maximum excess delay. We recovered a good value for the PLE for all of the frequencies, using the CI path-loss model. The smaller value of the distance-dependent factor indicates that the drop in the received power is low for the measured distance in this particular NLOS-I2O environment.  
\begin{table}
\begin{tabular}{l c c c c c c c c} \hline \hline \multirow{2}{*}{**Source**} & **Frequency Range** & **Distance (m)** & **PLE (n)** & \(\alpha\) & \(\beta\) & \(\gamma\) & \(\sigma_{\text{CI}}\), \(\sigma_{\text{ABG}}\) & \(\tau_{\text{rms}}\) (ns)** \\ \cline{1-1}  & **(GHz)** & & & & & & & \\ \hline [PERSON] et al. [33] & \(28,73\) & \(4.1\) & \(1.1\)–\(3.5\) & – & – & – & \(1.7\)–\(9\) & \(4.1\)–\(21.2\) \\ \hline [PERSON] et al. [15] & \(28,73\) & \(4.1\) & \(1.1\)–\(3.5\) & \(\begin{array}{c}0.9\\ 1.1\end{array}\) & \(17.7\)–\(47.1\) & \(2.5\)–\(3.5\) & \(\begin{array}{c}1.8\)–\(8.6\\ 1.8\)–\(14.2\end{array}\) & \(0.5\)–\(143.8\) \\ \hline [PERSON] et al. [32] & \(38,60\) & \(19\)–\(265\) & \(1.9\)–\(4.6\) & – & – & – & – & \(<\)122 \\ \hline [PERSON] et al. [27] & \(28,40\) & \(\leq\)\(100\) & \(1.89\) & – & – & – & – & \\ \hline Ours & \(19,28,38\) & \(<\)\(15\) & \(0.4\)–\(1.5\) & \(0.2\) & \(5.8\) & \(5.4\) & \(1.7\)–\(4.1,2.5\) & \(8.2\)–\(29.2\) \\ \hline \hline \end{tabular}
\end{table}
Table 4: Comparison of propagation studies for path loss models and RMS delay spread for 5G channels at mmWave bands.  
The PLE values are 0.4, 0.8, and 1.5 at measurement frequencies of 19, 28, and 38 GHz, respectively. The average RMS delay spread values are 19.2, 19.3, and 20.3 ns at 19, 28, and 38 GHz, respectively. The presented results showed that the path loss and RMS delay spread are not linearly dependent. The strong received signal can be detected at a low delay spread. Finally, our results from this study, together with other propagation studies in the literature, contributes to the development of a more precise and unified channel model framework for the studied mmWave bands of 19, 28, and 38 GHz.  
Conceptualization, A.M.A.-S, T.A.R, M.H.A. and T.A.-H.; methodology, A.M.A.-S, T.A.R., M.H.A., T.A.-H., Y.F. and A.A.-M.; software, A.M.A.-S, T.A.R., M.H.A. and T.A.-H.; validation, A.M.A.-S, T.A.R., M.H.A., T.A.-H., Y.F. and Y.A.A.-G.; formal analysis, A.M.A.-S, T.A.R. and T.A.-H.; investigation, A.M.A.-S, T.A.R. and T.A.-H.; resources A.M.A.-S, T.A.R. and T.A.-H.; data curation, A.M.A.-S, T.A.R., T.A.-H.; writing--original draft preparation, A.M.A.-S; writing--review and editing, A.M.A.-S, T.A.R, M.H.A., T.A.-H., Y.F., Y.A.A.-G. and A.A.-M.; visualization, A.M.A.-S, T.A.R. and T.A.-H.; supervision, T.A.R.; project administration, A.M.A.-S., T.A.R. and T.A.-H.; funding acquisition, T.A.R. and T.A.-H. All authors have read and agreed to the published version of the manuscript. This work was supported in part by H2020-MSCA-RISE-2015 under grant 690750. This research was also funded by the Research Management Centre (RMC), Universiti Teknologi Malaysia (UTM), under the Wireless Communication Centre HICOE Grants. It was also supported by HICOE, Universiti Teknologi Malaysia (UTM) under Grant Q.J091300.23C9.00D96. No conflict of interest is declared by the writers.  
No. References