# A Survey of Vehicular VLC Methodologies
## 3 Vehicular VLC Overview
### Infrastructure-to-vehicle reviews  
The authors in [74] conducted an analysis of the performance parameters of a Vehicle-to-Infrastructure (V2I) connection using Visible Light Communication (VLC) in a two-road scenario, where automotive headlights served as transmitters to connect with traffic light poles. They established that the road infrastructure met the necessary criteria, with the traffic light poles featuring colored lighting (yellow, green, and red) and three nearby photodiodes. Realistic Channel Impulse Response (CIR) reports were generated using ray tracing, demonstrating the impact of LED front-end characteristics on channel performance and the influence of optical CIRs. The study also explored the effects of lateral shifting on V2I communication by initiating measurements from various positions while the vehicle was in motion. Based on these parameters, calculations were performed to determine the maximum achievable data rates in each V2I scenario. In another work, [35], coordinated multipoint transmission (CoMP) was employed to establish a dynamic handover method. The proposed method considered variations in received power levels and recalculated delivery aspects and start-up time values without explicit information about the vehicle's speed. Results indicated that the proposed method outperformed conventional CoMP in terms of consistent signal quality during handovers, irrespective of vehicle speed. The study also examined how vehicle speed affected the received signal-to-noise ratio. Additionally, to achieve low latency in VLC system communication for traffic signals, the authors employed empirical characterization and analysis of optical performance [80]. They used a typical optical signal, considering the effect of optical diodes and custom amplified optical capacitors, to transmit digital information to the receiving stage. The packet error rate was calculated in terms of the effective field of view (EFOV). System performance measurements were taken at varying distances between the receiver and transmitter, using a wide range of optical capacitors from 3 to 50 m. The study showcased different responses based on the angle, with lens cases exhibiting an EFOV greater than 150 degrees being unsuitable for distances beyond 20 m. The findings demonstrated a range of responses depending on the angle due to the measuring connection's placement. Moreover, the lenses were observed to significantly improve the packet error rate from 105 up to 50 m while maintaining an EFOV of more than 10 degrees. Another study utilized non-sequential ray tracing to analyze and describe the effectiveness of Infrastructure-to-Vehicle (I2V) connections using street lighting [36]. The authors provided closed-form expressions for path loss terms, probability distribution functions (PDFs), and connection parameters. They considered parameters such as column height, receiver aperture size, lateral displacement, and distance between traffic illumination poles and assessed their impact on the system and bit error rate. The proposed path expression was compared with Monte Carlo simulations, with the aim of achieving higher accuracy and complexity compared to the conventional Lambertian pattern model. The Lambert pattern exhibited an error of 25%, while the suggested polynomial models, with 12 coefficients, achieved an error of about 8%. In [81], a VLC channel was specifically designed for I2V communications with traffic lights in a real urban road scenario. Three models were proposed to describe the connections between traffic lights and vehicles, considering the limitations of the Lambert model. The accuracy and complexity of the proposed models were compared to the Lambert model, revealing a reduction in error to about 8% with 12 coefficients, while the Lambert pattern model exhibited an error of 25%.