## 2 Curtain Workshop Scenario
### 3D Ray Launching Simulation Software
The height for the transmitter and receiver in this scenario is 1.2 m, and the distance between the two measurement points is 1 m.  
For the measurements, a voltage-controlled oscillator (VCO) has been used to generate the RF signal at 2.4 GHz. The transmitted power at 2.4 GHz was 8.2 dBm, which falls into the typical range of XBee ZigBee motes employed in the final solution. The received RF power level has been measured by means of a portable spectrum analyzer (FSH20 from Rohde and Schwarz, Munich, Germany). Both the transmitter (i.e., the VCO) and the spectrum analyzer have been paired with the Omni-directional Broadband Antenna OmniLOG(r) 30800 (Gewerbegebiet Aaronia AG II, Strickscheid, Germany), which presents a gain of \(-6\) dBi at the 2.4 GHz band. Figure 5 presents the setup for the measurements. The simulation of the two case studies presented in Figure 4 has been performed applying the same conditions and parameters used in the empirical experiments, i.e., the same antenna type, transmitted power level, antenna gains, operating frequency, transmitter locations, etc. Table 2 shows a summary of the main parameters configured for the 3D-RL simulations. The simulation tool considers electromagnetic propagation phenomena such as diffraction, refraction, and reflection (the maximum number of permitted reflections of a ray is set by the user; in this case, it has been set to 6, as given by the convergence analysis described in [26]). It is worth noting that the employed 3D-RL simulator provides results for the complete volume of the scenario under analysis, enabling the analysis of any potential device location at any given height if required. Figure 4: The two measurement campaigns carried out for the validations of the 3D ray launching algorithm, (**a**) measurement points (1 to 16) covering the entire area of the workshop and (**b**) measurements for a LoS linear path. Figure 6 presents the comparison between measured and simulated results in terms of received RF power level. Figure 5(a) shows the results corresponding to 16 measurement points from Figure 5(a) (scenario 1), while Figure 5(b) shows the results corresponding to the linear path presented in Figure 5(b) (scenario 2). As can be seen, the results show a good match, validating the simulator for further radio analysis tasks within the workshop under analysis. Additionally, Table 3 presents the obtained mean error, the variance, and the standard deviation for the two analyzed scenarios. It is worth noting that the proposed methodology can be extended to any required frequency range, enabling the consideration of other wireless communication standards as a function of coverage/capacity requirements, such as PLMN-based IoT connectivity (e.g., 4G NB-IoT/LTE Cat. M, 5G D2D connectivity mainly within the 5G NR FR1 band, although extendable towards 5G NR FR2, etc. ), evolutions in LPWAN, or updates in 802.11 IoT connectivity (e.g., 802.11 ah WiFi Ha-Low). \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & **Value** \\ \hline Operating frequency & 2.4 GHz \\ Transmitted power & 8.2 dBm \\ TX gain & \(-\)6 dBi \\ TX1/TX2 heights & 1.75 m/1.2 m \\ Launched ray resolution (\(\Delta\Phi\)) & \(1^{\circ}\) \\ Maximum number of reflections & 6 \\ Mesh resolution & 50 cm \(\times\) 50 cm \(\times\) 20 cm \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Parameter configuration for the simulations using the 3D-RL tool. Figure 5: Employed transmitter and receiver configuration for the radio channel measurements: (a) the VCO as a transmitter; (b) the spectrum analyzer as a receiver.