# A Survey of Vehicular VLC Methodologies
## 3 Vehicular VLC Overview
### Prototype scenarios reviews  
There are some shortcomings in the works that support real-world scenarios because most of the results rely on experiments and simulations. In this section, we summarize the most important works dealing with the practical aspects of vehicular VLC communications. The authors in [8] studied the first realistic driving test of the V2V VLC system, where a working range of up to 45 m was achieved. The optical system technique was used in the receiver device, and the OFDM technique was used to send symbols to the transmitter device. Moreover, the angle of incidence and distance significantly impact energy. They were received, with road environments and reflections of neighboring vehicles having little effect on performance. The study also showed that the factor that leads to beam drops is when the LoS paths between the taillights and the receiver are blocked; this provides justification for placing the receiver in the middle, to achieve the LoS paths. LED signs also generate interference. This results in a transmission disruption that encryption techniques can handle. Furthermore, in [84], a system prototype proposed for hybrid communications was introduced by integrating RF radio communications technologies with VLC in vehicles to achieve communication continuity over longer distances. This is because visible light is suitable for V2V communications only within short distances. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Ref.** & **Year** & **Application** & **Light Source** & **Channel Method** & **Observations** \\ \hline \multirow{4}{*}{[35]} & \multirow{4}{*}{2020} & \multirow{4}{*}{I2V} & & & - & Two-lane road; \\  & & & & - & A single PD located on the top of a car; \\  & & & & - & A streetlamp with asymmetrical light; \\  & & & & - & Effect of blockage on handover; \\  & & & & & - & CIR calculation and analysis; \\  & & & & & - & Simulation in non-sequential ray tracing. \\ \hline \multirow{4}{*}{[80]} & \multirow{4}{*}{2020} & \multirow{4}{*}{I2V} & & & - & Analyzing Field of View (EFOV); \\  & & & & - & Calculate Packet Error Rate (PER); \\  & & & & - & Analyzing an optical channel model; \\  & & & & - & An empirical analysis test; \\  & & & & & - & Lambertian model of traffic light LED; \\  & & & & & - & Obtain minimize latency; \\  & & & & & - & Effects of non-LoS. \\ \hline \multirow{4}{*}{[73]} & \multirow{4}{*}{2021} & \multirow{4}{*}{V2V} & \multirow{4}{*}{Asymmetrical} & \multirow{4}{*}{Ray tracing} & - & Obtain the channel responses (CIRs); \\  & & & & - & Derived path loss mode; \\  & & & & - & Obtain BER; \\  & & & & & - & Investigate RMS delay spread; \\  & & & & - & Use different commercial taillights. \\ \hline \multirow{4}{*}{[81]} & \multirow{4}{*}{2021} & \multirow{4}{*}{I2V} & \multirow{4}{*}{Lambertian} & \multirow{4}{*}{Experimental} & - & Channel characterization for I2V; \\  & & & & - & Real traffic light in a typical urban road; \\  & & & & - & The Lambertian channel model; \\  & & & & - & Receiver is located at 3 different heights; \\  & & & & & - & Experimental measurement setup; \\  & & & & - & Obtain bit error rate (BER); \\  & & & & - & Measure signal-noise-ratio (SNR). \\ \hline \multirow{4}{*}{[83]} & \multirow{4}{*}{2022} & \multirow{4}{*}{I2V} & \multirow{4}{*}{Asymmetrical} & \multirow{4}{*}{Ray tracing} & - & Obtain BER performance; \\  & & & & - & Derive a closed-form expression; \\  & & & & - & Asymmetric LED light TX; \\  & & & & - & Obtain minimize latency; \\  & & & & - & Receiver aperture of PD; \\  & & & & - & Lateral shift and height between I2V; \\  & & & & - & Longitudinal distance between I2V. \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._Therefore, RF communications complement the system, covering all areas and providing in-network information about road infrastructure, spaces, sensor analysis, and traffic.