# Laser-Based Mobile Visible Light Communication System
## 1 Introduction
The system operates at ultrahigh data rates of more than 35 Gb/s with a coverage area of 39 m\({}^{2}\) at a link distance of 4 m [14]. The fused fiber-optic tapers designed by [PERSON] et al. offer a wide-FOV laser reception solution. The optical detector offers a high efficiency, broad modulation bandwidth, indefinite stability, and operates over a wide range of wavelengths. Between \(-32.5^{\circ}\) and \(32.5^{\circ}\), the system can support 1 Gbit/s using on-off keying (OOK) based on a 642-nm laser [15]. [PERSON] et al. experimentally compared the performances of an  
Figure 1: Indoor mobile VLC application scenario. engineered diffuser (ED) and ground glass diffuser (GGD), and verified the diffusion effect of a green LD through a diffuser, enabling transmission at a rate of 1 Gbps within a half-angle range of 12\({}^{\circ}\) in a 2 m air channel. The light source can also support communication in a 2 m water channel [16]. In our previous work, by exciting fluorescent ceramics with an inclined blue laser, we achieved an FOV of 34\({}^{\circ}\). At a 1 m distance, the highest data rate can exceed 3.7 Gbps at the center, and the overall transmitting rate is beyond 3 Gbps within a 34\({}^{\circ}\) range [17]. By placing an engineered diffuser at the transmitter and using a Silicon Photomultiplier (SiPM) for reception, this angle can be further expanded to 180\({}^{\circ}\)[18]. These wide-FOV laser-based VLC solutions provided numerous references for this work. The realization of wide-FOV communication provides solutions for the transmitting and receiving devices in mobile VLC systems, and research has also expanded into mobile VLC channel and system models. [PERSON] et al. studied the variations in mobile channels between cars through image optical flow, which is the coordinate changes of the VLC transmitter in images during movement, and established a motion model for theoretical research. Simulations based on proposed motion models indicated motion characteristics for infrastructure-to-vehicle VLC, vehicle-to-infrastructure VLC, and vehicle-to-vehicle VLC [19]. [PERSON] et al. conducted vehicle-to-infrastructure channel estimation based on decision feedback. Through simulation under this method, an effective visible light communication link can be established when the vehicle's moving speed is 15 m/s [20]. [PERSON] et al. developed a model for high-speed train communication, exploring the impact of the Doppler effect on this type of high-speed mobile VLC model. Adaptive modulation schemes were investigated for both the single-input single-output (SISO) system and the MIMO system under the high-speed mobile VLC model [21]. [PERSON] et al. established a noise model for vehicular VLC to obtain the optimal error performance [22]. [PERSON] et al. established a simulation model for mobile vehicles and multiple streetlights to investigate the switching strategy between adjacent streetlights, aiming to prevent signal interruption caused by light source switching. Their receiving signal power (RSP) handover scheme can ensure normal communication between vehicles and lights with a low cost, increased signal-to-noise ratio (SNR), and reduced bit error rate (BER) [23]. [PERSON] et al. improved the system degrees of freedom by addressing channel crosstalk with delay-adaptive techniques through simulation studies [24]. These works provide a solid theoretical foundation for research on mobile VLC, thoroughly demonstrating the potential of VLC applications in mobile environments, while there is currently a significant lack of research on experimental systems for mobile VLC. The first demonstration was proposed by [PERSON] et al. in 2016, and they suggested orthogonal circulant matrix transform (OCT) precoding to be a promising way to deal with the high package loss rate [25]. In 2018, [PERSON] et al. put forward another experiment, where the transmitting rate was only 4 kbps [26].