# Performance of Millimeter Wave Dense Cellular Network Using Stretched Exponential Path Loss Model
## 4 Simulation Results and Discussions
It is found that the SINR coverage probability is reduced at a small cell radius (\(r_{c}=50\) m) because as the cell radius is decreased, the distance between BSs is reduced, which brings the interfering BSs closer to the tagged BS. As a result, coverage probability decreases due to strong network interference that lies closer to tagged BS. Furthermore, at increased cell radius, the reflections may enable NLOS links and hence the increase in coverage probability due to NLOS paths. It has also been observed in [22; 48] that NLOS paths provide sufficient gains to recover for path loss due to the LOS link. Moreover, at increased cell radius, the obstructions are more, causing some of the dominant interference to be suppressed, thereby enhancing the coverage probability. To elaborate further, in Figure 4, the SINR coverage probability of LOS and NLOS path is plotted along with the total coverage probability for different values of cell radii, \(r_{c}=50\) m and \(r_{c}=100\) m. It can be observed that the probability of NLOS coverage is higher than the LOS coverage for a larger cell radius. This is in line with the observation in [38], that at increased cell radius, the associated BS is mostly in NLOS with the UE. \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline \(f\) & 28 GHz \\ \(B\) & 500 MHz \\ \(G_{0j},j\in\{UE,BS\}\) & 10 dB \\ \(G_{sl,j},j\in\{UE,BS\}\) & \(-10\) dB \\ \(\theta_{j},j\in\{UE,BS\}\) & 30\({}^{\circ}\) \\ \(r_{c}\) & \(\sqrt{\frac{1}{\pi\lambda}}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Parameters for numerical evaluation of system model. Figure 3: SINR coverage probability \(P_{c}(T)\) vs. SINR threshold (T) for different blockage environment. (**a**) obstacle scaling factor (\(\zeta=1\)) (**b**) obstacle scaling factor (\(\zeta=2\)). In Figure 5, the effect of BS density on SINR coverage probability is studied for different values of obstacle scaling factor (\(\zeta\)). It is observed that the total coverage probability decreases exponentially to zero for high BS density. It is also observed that when BS density is low, the NLOS coverage probability is higher than the LOS coverage probability implying that in the closest association, UEs are associated with NLOS BS. As BS density increases, NLOS coverage keeps on decreasing. On the other hand, LOS coverage is initially low and begins increasing but does not increase significantly as BS density increases. This is because of the fact that, as BS density increases, the aggregate network interference increases, causing a reduction in coverage probability. These results are in line with various research [38; 49; 50]. The drop in coverage probability is more for higher values of \(\zeta\), which represents a highly obstructive environment. Similar insights for the downlink microwave network are obtained in [33]. According to our system model and assumption, the total coverage probability follows a trend similar to the coverage of the NLOS path. This emphasizes the significance of NLOS links in mmwave communication. \({}^{\text{HM}}\)In Figure 6 the impact of different BS antenna parameters is studied on the SINR coverage probability at \(r_{c}=100\) m. The UE beam is fixed at \(G_{\text{{O}}LIE}=10\) dB, \(G_{\text{{O}}sl}=-10\) dB and \(\theta_{UE}=30^{\circ}\). It can be observed that increasing the BS antenna gain increases the coverage probability. Whereas increasing the beamwidth of the BS antenna makes the main lobe wider, and coverage probability is reduced due to a decrease in directionality. Figure 4: SINR coverage probability \(P_{c}(T)\) vs SINR threshold (T) with LOS and NLOS path. (**a**) cell radius (\(r_{c}\)) = 50 m (**b**) cell radius (\(r_{c}\)) = 100 m.  
Figure 5: Impact of BS density on SINR coverage probability for different blockage environment. (**a**) obstacle scaling factor, \(\zeta=1\) (**b**) obstacle scaling factor, \(\zeta=2\).