## 2 Materials and Methods
### The Channel Simulator  
The material employed in this study comprises a communication channel simulator crafted using Python. Initially, the foundation for this simulator drew inspiration from a primary version based on MATLAB, as documented in reference [27]. Our improved Python simulator not only operates on an open-source platform but also brings novel simulation parameters. These enhancements encompass the introduction of an innovative smoke model, the integration of 3-D graphical representations, increased flexibility for customizing simulation \"room\" parameters or outdoor configuration, and the consideration of authentic lamp radiation patterns. The channel simulator presented in this study can be found on Github [28]. It empowers users to incorporate radiation measurements provided by light fixture manufacturers, typically available in formats such as the redllluminating Engineering Society (IES) or EULUMDAT [29]. These files encompass comprehensive information about the light fixture, its characteristics, and the associated radiation pattern. Users can integrate these data into the simulator for precise simulation in each specific situation, enhancing the accuracy and realism of VLC performance assessments. The simulator has, for example, been applied in various smart city or concrete industrial use cases in the past [21]. The present simulator is an enhanced version of our previous work where the communication simulator was upgraded to include several modulation schemes such as orthogonal frequency division multiplexing (OFDM) and universal frequency multi carrier (UFMC), together with the introduction of performance measures. Figure 5 explains the simulated environment and the basic principle of the simulator. The aim of the simulator is to assess the optical power distribution of a VLC system in a scenario under study. To do so, the software creates first a virtual three-dimensional room where the axes' origin is in the center. Here, the light is in the center of the ceiling, and the reception plane is located at the same distance from the origin as the emitter but in the negative application of the Cartesian coordinate system. Then, several parameters can be set such as the presence of walls or not, their reflection coefficients, and the position of the emitter in the virtual room. Afterward, the reception plane where the communication coverage needs to be assessed is set. It should be noted that the tilting of the emitting light or receiver is not taken into account. As mentioned before, only the scenarios that can benefit from a major part of LoS are considered here. The walls are subdivided into a matrix of unit surfaces to assess the quantity of power coming from the LED and then acts as a Lambertian point source. The ground being also subdivided in unit cells enables the computation of the portion of optical power reaching the receiver at each cell of the receiver's plane cell. Figure 5: 3-D environment simulated when using the software-wall can be made transparent to take into account outdoor scenarios or the presence of windows. In the scope of this paper, a scenario where a light source is hanging on a wall was chosen to study the performances of the UFMC modulation scheme. Figure 6 shows (left) the setup under study where the light source is enlightening the pedestrian under it and its connected device, as well as (middle and right) the resulting optical power coverage map. To be as close to reality as possible, a 47 W streetlight NIRKON MURAS with a light temperature of 4000 K was selected. Its corresponding IES file was obtained from the Luminescent website, as referenced in [26]. This file contains the light's name and radiation pattern, defined by a table using the two angles C and Gamma. The IES file encompasses data for 13 azimuth angles (ranging from 0 to 360 degrees with a 30-degree interval) and 181 elevation angles (ranging from 0 to 180 degrees with a 1-degree increment).