## 2 Curtain Workshop Scenario
### 3D Ray Launching Simulation Software  
The 3D ray launching (3D-RL) code used in this study is based on the principles of geometric optics and the uniform theory of diffraction, which involves launching rays from  
Figure 2: RF interference measurements within the factory workshop at the 2.4 GHz band. predefined sources with a given angular resolution in both horizontal and vertical planes. The simulation considers all the objects and frequency dispersive material properties, such as the conductivity and relative permittivity of elements in the scenario, including machinery and walls. Diffraction and diffuse scattering are also considered in the simulation. To reduce computational complexity, the simulation code has been optimized to include hybrid simulation options, such as neural network-based interpolators, diffraction estimation based on the electromagnetic diffusion equation, and collaborative filtering database extraction. A detailed description of the code can be found in [23], and it has been tested and validated in various use cases and applications, including industrial environments [24]. The factory workshop scenario created for the 3D-RL simulation has dimensions of 31 m in length, 34 m in width, and a height of 6 m, resulting in an overall volume of approximately 6324 m\({}^{3}\). Figure 3 shows a view of the complete schematic factory model developed for the simulations. All elements within the workshop, including machinery, metallic elements, and walls, are considered for the analysis of their impact on radio propagation. Table 1 presents the main material properties of all the existing elements within the presented scenario, which are taken from [25]. Once the scenario has been created, a comprehensive series of radio frequency measurements have been carried out to validate the deterministic estimations provided by the 3D Ray Launching simulator. These measurements were taken for the ZigBee frequency band of 2.4 GHz. In order to ensure a fair validation, two different measurement scenarios have been proposed, where different propagation conditions within the workshop have been included and analyzed, such as line of sight (LoS) and nonline of sight (NLoS) conditions. These two measured cases are presented in Figure 4. In the first scenario (Figure 4a), the location of the transmitter (height of 1.75 m), labeled \"Tx\" in the figure, was chosen to \begin{table}
\begin{tabular}{c c c} \hline \hline
**Elements** & **Relative Permitivity (\(\epsilon_{r}\))** & **Conductivity (\(\sigma\)) [S/m]** \\ \hline Air & 1 & 0 \\ Metal & 4.5 & \(37.8\times 10^{6}\) \\ Glass & 6.06 & 0.11 \\ Plastic & 8.5 & 0.02 \\ PVC & 4 & 0.12 \\ Brick wall & 4.44 & 0.11 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Relative permittivity and conductivity of the existing elements within the created scenario. Figure 3: The created workshop scenario for its simulation by the 3D Ray Launching tool. enable a thorough investigation of the RF power level in different areas under both line of sight (LoS) and nonline of sight (NLoS) conditions. The measurement points, represented by numbered red circles, have been strategically distributed covering the entire area of the workshop, being located at different heights on machinery, shelves, and aisles (in aisles at 1.2 m height). This distribution provides valuable information on the radio propagation for the different wireless links present in the workshop. In the second scenario, the study has been designed to evaluate wireless propagation for a linear path, as can be seen in Figure 3(b). This path corresponds to an aisle of the workshop, and the aim of this case study is to obtain the RF behavior for a continuous LoS condition. To this end, the measurement points were distributed along this linear path (represented by the white arrow in the figure).