# Evaluation of Deployment Challenges of Wireless Sensor Networks at Signalized Intersections
## 3 Simulation Results
It has been calculated using as threshold the noise floor, with a value of \(-100\) dBm. Figure 6: Estimation of received power (dBm) on the considered scenario (\(YZ\) planes) for different distances of \(X\) obtained by the 3D Ray Launching algorithm (**a**) \(X=73\) m for the sensor #6; (**b**) \(X=55\) m for sensor #9. Figure 7: _Cont_. From Figure 8 it can be seen that multipath phenomena have a lot of influence in the environment. It is observed that the delay spread is higher in the areas closest to the transmitter antenna and it is lower in other areas because the radiation power in these parts is smaller due to the larger distance. Each spatial sample of the delay spread is associated with a power delay profile, shown in Figure 9 for the central position of the scenario. As it is observed, the scenario is really complex and there are several echoes in the scenario due to this multipath channel behavior. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Zone** & **Area (m\({}^{2}\))** & **Power Mean (dBm)** & **Standard Deviation (dB)** & **Obstacles Density (\%)** \\ \hline \hline \multicolumn{5}{c}{**CASE I Sensor \#1**} \\ \hline
**I** & 700 & \(-\)54.57 & 1.96 & 0.43 \\
**II** & 875 & \(-\)53.27 & 1.70 & 0.57 \\
**III** & 3675 & \(-\)68.47 & 9.09 & 0.04 \\
**IV** & 5600 & \(-\)47.86 & 2.27 & 0.86 \\
**V** & 400 & \(-\)36.81 & 5.16 & 0.10 \\
**VI** & 4550 & \(-\)57.28 & 1.08 & 0.02 \\
**VII** & 2100 & \(-\)58.96 & 2.22 & 0 \\
**VIII** & 1600 & \(-\)52.27 & 1.14 & 0.26 \\ \hline \multicolumn{5}{c}{**CASE II Sensor \#6**} \\ \hline
**I** & 1400 & \(-\)65.10 & 5.61 & 0.80 \\
**II** & 9750 & \(-\)54.86 & 1.64 & 0.38 \\
**III** & 4300 & \(-\)45.50 & 1.46 & 0.14 \\
**IV** & 800 & \(-\)41.71 & 1.81 & 0 \\
**V** & 100 & \(-\)35.51 & 2.94 & 0 \\
**VI** & 1750 & \(-\)53.98 & 3.03 & 0.59 \\
**VII** & 1400 & \(-\)63.28 & 7.12 & 0.43 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Simulation results divided by zones. Figure 7: Estimation of received power (dBm) on the considered scenario (\(XY\) planes) divided by zones obtained by the 3D Ray Launching algorithm (**a**) 1.4 m height for the sensor #1; (**b**) 1.4 m height for sensor #6. As previously shown, a clear dependence on the topology and morphology of the scenario as well as on the system parameters is observed and must be carefully considered in order to assess the performance of multiple systems within a particular scenario. These results allow the optimization of the design of the WSN since the designer can select the minimum number of nodes required to grant a certain communication level, and the optimal emplacements of these nodes. It is important to consider also that a larger density of nodes can lead to increased interference levels, which could degrade system performance. This comment also applies in the case of changes in the transmitted service, associated with a certain allocated bandwidth and hence, changes in sensitivity levels. The computational time is also highly important when analyzing these complex scenarios. In this case, simulations have been performed in an Intel Xeon CPU X5650 @ 6.67 GHz and 2.66 GHz, and the simulation computational time has been of 43,537 s using the software Matlab from Mathworks (Natick, MA, USA). It must be pointed out that the input parameters have been chosen according to a convergence analysis of the algorithm previously done for different types of scenarios [41]. A key parameter that is used in assessing systems that transmit digital data from one location to another is the Bit Error Rate (BER). The \(BER\) expression for QPSK modulation can be calculated by:  
\[BER_{\text{QPSK}}=Q(\sqrt{2E_{\text{b}}/N_{0}}) \tag{3}\]  
Figure 8: Estimation of delay spread (ns) on the considered scenario for different positions of the transmitter antenna in different traffic street lights (a) 3 m height for sensor #5; (b) 3 m height for sensor #6. Figure 9: Power Delay Profile at a given cuboid, located at the central location in the considered scenario.