## 5 Simulation Study
### Simulation Results and Discussion  
We observe the effect of increasing the number of wireless nodes on system performance. Using the OPNET Modeler simulator, we measure packet delays, throughput, P2P file sharing, download file size, response time, traffic sent, traffic received, and the FTP file sharing download response time, upload time, traffic sent, and traffic received. The simulations run for 300 s with varying nodes, and the results are recorded and analyzed. The summary of the simulation results is presented in Figure 14a-j.  
Figure 12: OPNET representation of 802.11n network model with N = 50 nodes.  
Figure 14a shows that the network throughput of the 802.11n infrastructure network increases with the number of nodes (N), with a more significant increase for N > 30. Figure 14b shows that the packet delays increase with the number of nodes. Figure 14c,d show the results of P2P file sharing download response time. We observe that there is a significant difference in download response times between low- and high-traffic scenarios with an increasing number of nodes. The download response times show a fluctuating trend with an increasing number of nodes.  
\begin{table}
\begin{tabular}{l l} \hline \hline
**Parameter** & **Value** \\ \hline Network scale & Office \\ \hline Area & 50 \(\times\) 100 Square meters \\ \hline Network size (number of nodes) & Up to 50 \\ \hline Mobility model & Random way point \\ \hline Data rate & 26 Mbps (base/240 Mbps (max)) \\ \hline Physical characteristics & HT PHY 2.4 GHz (802.11n) \\ \hline Transmit power (W) & 0.005 \\ \hline Packet reception power & \(-\)92 dBm \\ \hline Channel & Auto assign \\ \hline Buffer size (bits) & 256,000 \\ \hline \multirow{3}{*}{FTP traffic} & Low load (1000 bytes) \\  & Medium load (5000 bytes) \\  & High load (50,000 bytes) \\ \hline \multirow{3}{*}{P2P file sharing} & Low traffic: \\  & Minimum outcome 10,000 (bytes) \\  & Maximum outcome 100,000 (bytes) \\  & High traffic: \\  & Minimum outcome 100,000 (bytes) \\  & Maximum outcome 10,000,000 (bytes) \\ \hline Simulation time & 300 s \\ \hline \hline \end{tabular}
\end{table}
Table 6: General parameters used in the simulations.  
Figure 13: Sample OPNET simulation configurations. (**a**) Application configuration and (**b**) profile configuration.  
Figure 14: Summary of simulation results (**a-j**). (**a**) Effect of increasing the number of nodes on packet delays; (**b**) effect of increasing the number of nodes on throughput; (**c**) P2P file sharing download file size versus nodes; (**d**) P2P file sharing download response time versus nodes; (**e**) P2P file sharing traffic sent versus nodes; (**f**) P2P file sharing traffic received versus nodes; (**g**) FTP file sharing download response time versus nodes; (**h**) FTP file sharing upload response time versus nodes; (**i**) FTP file sharing traffic sent versus nodes; and (**j**) FTP file sharing traffic received versus nodes.  
Figure 14e,f show the traffic sent and received, respectively, for different P2P file-sharing scenarios with an increasing number of nodes. There is a noticeable difference between low and high traffic in terms of increasing traffic sent and received. Figure 14g,h show the results for the download and upload response time, respectively, for various FTP traffic loads. The download response times increase with the number of nodes, while upload response times fluctuate.  
Figure 14i,j show the relationship between traffic sent and traffic received for various FTP loads (low, medium, and high) for an increasing number of nodes. The results show a significant increase in the FTP traffic sent as the number of nodes increases, with no clear relationship between traffic sent and the number of nodes. Additionally, there is not much disparity between the traffic received and traffic sent, although the mean traffic received increases with the number of nodes.