## 5 Reviewed Papers on Empirical-Based Path Loss Models
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Ref.** & \
\begin{tabular}{c} **Freq.** \\ **(GHz)** \\ \end{tabular} & **Model** & **Scenario** & **Environment** &
\begin{tabular}{c} **Area of** \\ **Focus/Methodology** \\ \end{tabular} & **Important Results** & **Drawback** \\ \hline
[66] & 26 & \begin{tabular}{c} 3 GPP, \\ ABG, and \\ CI \\ \end{tabular} & \begin{tabular}{c} LOS and \\ NLOS \\ \end{tabular} & \begin{tabular}{c} Outdoor- \\ rural \\ \end{tabular} & \
\begin{tabular}{c} A comprehensive \\ measurement \\ campaign was \\ conducted in two \\ rural areas using a \\ crane to assess path \\ loss at transmite \\ antenna heights of \\ 30, 50, and 70 m. \\ \end{tabular} &
\begin{tabular}{c} **The height of the cell** \\ site antenna appears \\ to be a crucial design \\ factor for network \\ planning. \\ \end{tabular} & There is need to test \\
[67] & 28 & \begin{tabular}{c} FSPL, CIB, \\ and CI \\ \end{tabular} & LOS & \
\begin{tabular}{c} Outdoor- \\ urban \\ \end{tabular} &
\begin{tabular}{c} The CIB path loss \\ model is suitable for \\ the LOS scenarios as \\ it aligns with the \\ data from the \\ loss for the 5G \\ system. \\ \end{tabular} & There is a need to \\
[68] & 28 & \begin{tabular}{c} NYUSIM \\ and CI \\ \end{tabular} & LOS and & Urban & \begin{tabular}{c} Urban \\ microcell \\ \end{tabular} & \begin{tabular}{c} parameters and \\ environmental \\ conditions for the \\ proposed millimeter \\ wave channels. \\ \end{tabular} & \
\begin{tabular}{c} Geometric \\ parameters and \\ external factors \\ affect the statistical \\ channel modeling’s \\ parameters. \\ \end{tabular} &
\begin{tabular}{c} For the suggested \\ model’s \\ performance to be \\ verified and \\ assessed, more \\ experimental data \\ are needed. \\ \end{tabular} \\ \hline
[69] & \begin{tabular}{c} 1.8, \\ 3.5, \\ and \\ 28 \\ \end{tabular} & \begin{tabular}{c} FI and CI \\ \end{tabular} & LOS & \begin{tabular}{c} Outdoor- \\ urban \\ \end{tabular} & \
\begin{tabular}{c} Modeling of path \\ loss from wideband \\ measurement \\ campaign. \\ \end{tabular} &
\begin{tabular}{c} A guiding effect was \\ noticed in the \\ 1.8 GHz frequency \\ band, which is not \\ observed in other \\ bands. \\ \end{tabular} & To check the stability \\
[70] & \begin{tabular}{c} PEF and \\ Log- \\ distance \\ \end{tabular} & LOS & Suburban & \begin{tabular}{c} Modeling of path \\ loss from wideband \\ measurement \\ campaign. \\ \end{tabular} & \
\begin{tabular}{c} 1.8 GHz frequency \\ band, which is not \\ observed in other \\ bands. \\ \end{tabular} &
\begin{tabular}{c} To check the stability \\ of the \\ should be taken into \\ account. \\ \end{tabular} \\ \hline
[70] & \begin{tabular}{c} PEF and \\ Log- \\ distance \\ \end{tabular} & LOS & Suburban & \begin{tabular}{c} The “drive test” and \\ “walk test” experiments were \\ conducted to \\ investigate \\ propagation loss \\ along distinct paths. \\ \end{tabular} & \
\begin{tabular}{c} With an RMSE that \\ was 1.4 dB lower, the \\ suggested model \\ performed better \\ than the log-distance \\ model. \\ \end{tabular} &
\begin{tabular}{c} The proposed model \\ needs to be tested on \\ other frequency \\ bands to accurately \\ determine the \\ stability of the \\ models. \\ \end{tabular} \\ \hline
[71] & 28 & \begin{tabular}{c} CI, FI, and \\ ZMS \\ \end{tabular} & LOS and & Indoor & \begin{tabular}{c} Simulation for all \\ possible polarization \\ at NLoS and LoS \\ scenarios per meter \\ over 47 m. \\ \end{tabular} & Indoor & \
\begin{tabular}{c} The straightforward \\ model that is \\ suggested, which \\ only has one \\ parameter called \\ ZMS, can forecast \\ expansive path loss \\ across distance. \\ \end{tabular} &
\begin{tabular}{c} To develop a model \\ that is representative, \\ a comprehensive \\ measuring campaign \\ across comparable \\ buildings will be \\ necessary. \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table}