## 2 Materials and Methods  
In the realm of visible light communication (VLC), even in outdoor environments, the optical power propagation from emitter to receiver is profoundly influenced by the specific scenario. Given that VLC operates with light, obstacles pose a significant challenge, acting as disruptors to communication. Additionally, reflections in the environment can have varying effects, either adding up constructively to the signal or introducing noise-like contribution at the receiver [22]. Recognizing these factors, smart city applications capitalizing on VLC could strategically align with scenarios where these requirements are inherently met, where there is mainly line of sight (LoS). This is particularly possible and advantageous for applications such as IoT, urban Li-Fi or OCC, vehicle-to-vehicle (V2V) communication, vehicle-to-infrastructure (V2I) communication, communication among drones, and various supplementary scenarios illustrated in Figure 2.  
Moving beyond the scenario considerations, it is essential to understand that while VLC utilizes LEDs for communication, the diversity of LEDs introduces a range of parameters within the emitter itself. Each LED functions akin to an antenna, possessing a distinct radiation pattern that delineates how the power consumed by the LED is distributed through space in an angular manner [23]. Notably, LEDs employed in different applications exhibit unique radiation patterns. For instance, LEDs designed for indoor lighting, also called Lambertian emitters, disperse light evenly in the room [24], while car headlights, street lights, and industrial lighting each carry their distinctive angular radiation signatures [21; 25]. Figure 3 shows a plane representation of the radiation pattern of a Lambertian emitter for three different half power angles (on the left side of the figure) and a NIKKON streetlight (on the right side of the figure). A Lambertian emitter has a uniaxial symmetry to the radiation pattern and its half-power angle parameter gives it directionality. Two perpendicular planes of the streetlight 3-D radiation pattern are represented on the right side of the figure. It can be seen that there is no axial symmetry and a preferred direction in the radiation of light power. Figure 2: Potential applications of VLC in Smart Cities. This paper underscores the nuanced interplay between the materials employed in visible light communication (VLC) systems, the configuration setup, and the surrounding environment. Recognizing the distinctiveness of each LED and its crucial positioning relative to the receiver in diverse scenarios, this paper introduces a simulator designed to empower end users to define these pivotal parameters. In its primary phase, the simulator allows users to intricately characterize the LED properties and spatial arrangement, considering the unique features of each light emitter. Additionally, it facilitates the assessment of communication performance under an innovative modulation scheme, UFMC. Notably, the simulator, also meant for outdoor communication, extends its functionality relative to the baseline literature to incorporate environmental factors, allowing users to specify the quantity of particles in the air and consequently identify optical power loss attributable to atmospheric presence. While a more comprehensive exploration of these atmospheric effects can be found in our earlier work [21], this paper concentrates on highlighting the simulator's versatility and the pertinence of VLC within the 6G paradigm. Figure 4 shows how both simulators work together to study a scenario. The MATLAB simulator focuses on generating the point-to-point communication data stream, and the Python channel simulator takes into account the path loss computation of the communication. The two combined give us communication performance metrics of a point in space in a scenario. The subsequent section delineates the simulator's key features and presents the primary outcomes obtained while employing the UFMC modulation scheme in regards to OFDM performance.