# A Survey of Vehicular VLC Methodologies
## 5 Vehicular VLC Applications
### Intersection Assistance  
Assistance at intersections is one of the main applications of vehicular VLC. It helps avoid collisions at intersections, making them safer. Alternative means of warning and coordination between vehicular communications are provided, in addition to the traditional method represented by a traffic light. The collision avoidance system at intersections is one of the primary examples of the assistance applications at a corner, where the vehicles face each other. Thus, it is possible to take advantage of the VLC links for the cars for face-to-face communication and also with the vehicles parked on the other side of the intersections. In addition, the traffic lights provide communication based on LEDs or through other components, which makes connection easier. Recently, the development of intersections has seen increasingly complex forms. Despite their complexity, paths can be redesigned by applying guidance and navigation methods and combining knowledge to control road traffic. Figure 7 shows the communication between vehicles (V2V) and between infrastructure and vehicles (I2V) or from vehicles to infrastructure (V2I) via streetlamps and traffic lights to exchange information. Vehicles use headlights and taillights in addition to traffic lights, which allows data privacy and digital safety to be preserved. Many works [23; 115; 116; 117; 38] have discussed the topic of intersection assistance applications. \begin{table}
\begin{tabular}{c c c c c} \hline
**Refs.** & **Transmitter** & **Receiver** & **Scenario** & \multicolumn{2}{c}{**Observations**} \\ \hline
[108] & White LED & Three PDs & V2V & - & Two lanes \\  & & & V2V & - & Straight road \\  & & & V2V & - & Turning path \\ \hline
[109] & Headlights & Four PDs & V2V & - & Single lane \\  & & & V2V & - & Straight road \\  & & & V2V & - & One direction \\ \hline
[37] & Headlights & Four PDs & V2V & - & Two lanes \\  & & & V2V & - & Straight road \\  & & & V2V & - & Omnidirectional coverage \\ \hline
[110] & Traffic Light & One PD & Hybrid & - & Single lane \\  & & I2V, V2I & - & Straight road \\  & & & V2I & - & Perfect alignment \\ \hline
[80] & Traffic Light & One PD & I2V & - & Single lane \\  & & & V2V & - & Straight road \\  & & & V2 & - & Perfect alignment \\ \hline
[111] & Streetlight & One PD & I2V & - & Two lanes \\  & & & V2V & - & Straight road \\  & & & V2 & - & Perfect alignment \\  & & & V2 & - & Channel estimation \\ \hline
[35] & Streetlight & One PD & I2V & - & Two lanes \\  & & & V2 & - & Straight road \\  & & & V2 & - & Lateral shift \\ \hline
[38] & Headlights and Taillights & & & V2V and V2I & - & Omnidirectional coverage \\  & & & V2V & - & Multi-lane and curved roads \\  & & & V2 & - & Intersections \\  & & & V2 & - & Perfect alignment \\  & & & V2 & - & Misalignment \\  & & & V2 & - & Lateral shift \\ \hline \end{tabular}
\end{table} 
Table 4: _Cont._For example, in [115], it was suggested that the data be encoded in transmitters and converted into light signals. A silicon/carbon wavelength division multiplexer is used in the receivers for decoding. I2V, V2I, and V2V traffic scenarios are generated and then developed to control the arrival of vehicles at the intersection and schedule them to cross at times that minimize delays and maintain a safe distance from one to the other. This work in [116] proposed using hybrid VLC and RF to deploy important safety messages (BSMs) in intersection applications instead of conventional vehicle RF communication. Moreover, relaying BSMs is also compared, where outage, latency, throughput, and performance improve dramatically. In [117], the authors proposed the use of microsimulation and traffic-controlled intersection analysis, using a mesh-cellular hybrid network configuration for a vehicle-to-everything (V2X) scenario, the request/response concept, and relative position estimation for route management, as well as a wave-length-division multiplexer (WDM) optical sensor in the receiver.