# Laser-Based Mobile Visible Light Communication System
## 2 Experiment Setup  
To achieve a wide FOV for a white-light laser source, we employed a diffuser plate to scatter a commercial high-power laser array, transforming it into a non-directional point light source. Additionally, the use of a plano-convex lens further enhanced the uniformity and stability of the light beam. The light source generated white light through the fluorescence conversion of 452 nm blue light. The fluorescent material absorbed the blue light and converted it into a broad wavelength light, the spectrum of which is shown in Figure 2a, while the chromaticity coordinates are presented in Figure 2b. The light source exhibited a color temperature of 8318 K and a color rendering index (CRI) of 67.6, both of which demonstrate a commendable current stability. More details about this light source and its illumination and communication performance can be found in reference [27]. The optical power distribution of the light source is shown in Figure 3. To obtain accurate optical power measurements, we used a bandpass filter with a wavelength of 450 nm before measuring its optical power. The power meter we used (LBTEK PPM200S-20-USB, Shenzhen, China) had a maximum incident beam diameter of 10 mm. Clearly, as the distance increased, the optical power gradually decreased. At the same distance, the power also attenuated with an increasing angle, with the maximum power at the central angle. When the distance was one meter, the optical power at the central angle was 368 uW, maintaining at a relatively high power level within a certain angle range, then dropping rapidly. Within a range of \(\pm\)10 degrees, the optical power remained above 300 uW. By 20 degrees, the power had already decreased below 100 uW. The overall trend at two meters was similar to that at one meter, with the maximum optical power at the center being 101.1 uW. Within a range of \(\pm\)10 degrees horizontally, the power remained above 80 uW, and beyond 10 degrees, the power attenuated rapidly. Centered on the orientation of the light source, the emission range of the light extended approximately 22 degrees to both the left and right. This characteristic offers a promising way for developing high-quality, wide-FOV laser illumination sources. Such a directional spread ensures that the illumination can cover a wide area while maintaining a focused intensity to support high-speed communication. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Light Source** & **Type** & **Technology** & **Moving** & **Transmitting** & **Distance** & **Organization** & **Year** & **Citation** \\ \hline LED car light & Simulation & Pinhole camera & & & & & & \\  & & model in image & & & & & & \\  & & sensor-based VLC & & & & & & \\  & & Decision feedback & & & & & & \\  & LED & Simulation & channel estimation & 15 m/s & 199 Mbps & 1.5 m & & & \\  & & and MIMO & & & & & & \\  & & Adaptive & & & & & & \\  & & modulation & & & & & & \\  & & Allan variance and & & & & & & \\  & & adaptive Gaussian & & & & & & \\ LED streetlight & Simulation & & mixture-model- & 50–70 km/h & N/A & 3–13 m & Xi’an University of Technology & 2023 & [22] \\  & & & based noise & & & & & \\  & & modeling & & & & & & \\ Multiple LED & Simulation & & transmitter RSP & 10–25 m/s & N/A & 3 m & Jiangsu University & 2014 & [23] \\  & & handover & & & & & & \\ RGB-LDs & Simulation & & Delay adaptation & 1 m/s & N/A & 3 m & University of Leeds & 2015 & [24] \\  & & technique & & & & & & \\  & & & & & & & & \\ Blue LD & Experiment & OCT precoding & 20 cm/s & 300 Mbps & 1 m & University of Hong Kong & & \\  & & Dynamic column & & & & & & \\  & LED & Experiment & matrix selection & 20–100 cm/s & 4.08 kbps & 60 cm & Hunan University & 2018 & [26] \\  & & algorithm & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Previous works on mobile VLC.