## 1 Introduction
Their field measurements showed that the standard readily supports V2V operation and maintaining the target bit error rate (BER) across varying inter-vehicle spacings requires judicious selection of the modulation-coding scheme. The study also quantified the narrow emission and reception cones of off-the-shelf fog lamps, supplying practical design constraints for the large-scale deployment of vehicular VLC. The study in [16] proposed an optical camera communication system integrated into vehicles, utilizing the existing LED lights in cars and standard cameras. This system enables region-of-interest signaling functionality for vehicles through their headlights or taillights. In [17], a vehicle positioning system based on V2V and Vehicle-to-Infrastructure (V2I) visible light communication was examined. In this system, a camera sensor captures the location information of LEDs mounted on tunnel infrastructure and vehicle taillights. The visible light signals carry predetermined location data and are reliably detected by the camera due to the high directivity of the visible light propagation, providing an effective solution for vehicle positioning in controlled environments like tunnels. The authors in [18] designed a VLC system featuring a transmitter and receiver tailored to V2V applications, highlighting its characteristics and capabilities. They demonstrated how VLC technology could be integrated with traffic signals to communicate with vehicles' LED lights, suggesting that this approach could potentially reduce the number of accidents. In [19], a prototype design of a VLC-based V2V system was presented for communicating hard brake warnings to the following vehicle. The system was designed with the primary goal of ensuring timely awareness of the hard braking action of a leading vehicle, which served as the key motivation for its development. The study of [20] presented a low-cost enhancement of vehicular communication networks (VCNs) for future intelligent transportation systems. It combined VLC, using white LEDs that were already installed in headlamps, with a custom control area network (CAN) bus interface accessed through the vehicle's on-board diagnostics port. Laboratory tests showed error-free VLC beaconing over a 1.5 m link, while the CAN interface reported a vehicle speed with high fidelity to a GPS reference. The results indicated that VLC beacons, if paired with inexpensive in vehicle data extraction, can bolster VCN robustness without costly RF spectrum requirements. The work of [21] introduced a bidirectional vehicular VLC demonstrator that uses unmodified motorcycle head- and rear-lamp assemblies as optical transceivers. Field tests were performed outdoors under full daylight, covering inter-vehicle spacings up to 30 m as well as multiple lateral and angular offsets. Link quality was mapped through the spatial distributions of SNR and the associated packet error rate, evaluated at symbol rates of 28 kBd and 57 kBd. These results established a reference data set for assessing full duplex VLC performance in realistic V2V scenarios. The authors in [22] proposed enhancing V2V communication through incorporating imaging receivers equipped with fresnel, aspherical, and combined lenses, mounted on the rear of receiving vehicles. Communication was established through the headlamps of the transmitting vehicle to the imaging receivers on the destination vehicle's rear. The study further revealed that V2V communication performance diminishes as the angle of incidence increases, primarily due to the reduction in received power. In [23], a field-programmable gate array-based vehicular VLC prototype was developed, utilizing a standard low-beam headlamp as an on-off keying (OOK) transmitter and a Zynq-7000 device to perform encoding, modulation, and demodulation functions.