# A Survey of Vehicular VLC Methodologies
## 1 Introduction
The primary emphasis was on uplink transmission from the user to a VLC access point, aiming to achieve a wide spectrum of visible light and high data rates, while also analyzing the efficiency level and performance of the VLC system. Addressing practical limitations, the review in [20] described channel models, transceivers, computational complexity, efficiency performance, and VLC systems for the physical layer, along with the algorithms used. Additionally, an indoor localization algorithm was proposed, focusing on fingerprints and discussing various aspects of VLC applications, including V2V communications, robotics, healthcare, and national defense. Summarizing the developments related to localization systems using indoor VLC, [21] examined several techniques, such as polarized light, light intensity fingerprinting, shadows, spatial beams, and reflectors, comparing them to other methods. The study concluded that VLC is a viable option for indoor localization, playing an essential role in navigation and intelligent building applications, while offering energy efficiency, low processing time, and minimal computational complexity. Furthermore, based on the techniques presented in the review in [22], VLC can provide seamless, high-capacity broadband connections, potentially reaching data rates in the gigabits-per-second range. In addition, [23] focused specifically on vehicular VLC technologies, with researchers discussing channel characteristics, identifying problems, and addressing the most critical challenges in vehicular communications. On the other hand, the benefits of using intelligent transportation system applications with the latest VLC technologies were discussed in [24]. The factors that hinder their implementation in transportation infrastructure were discussed as possible suggestions to  
Figure 1: Visible light spectrum region. overcome the challenges. This survey in [25] mainly focused on integrating RF with VLC systems and the associated challenges and benefits. Additionally, the authors discussed the design of VLC systems, including their advantages, performance, limitations, and channel modeling. In [26], a comprehensive study on the theoretical foundations of VLC was introduced. The authors discuss various models for major VLC applications, such as indoor, underwater, outdoor, and underground applications. Finally, the study in [27] discusses machine learning (ML) application scenarios and the architecture of VLC. Many essential methods of VLC are also discussed, such as light modulation and channel modeling. Table 1 summarizes the surveys mentioned above and lists the subjects covered by these surveys. The concept of vehicular VLC is a crucial enabler for ITSs to improve road safety, traffic flow, and fuel consumption efficiency, facilitating the exchange of critical information between vehicles and infrastructure and having an important impact on the development and progress of transportation systems. Thus, this will lead to a fundamental change from autonomous to cooperative driving, with all the capabilities of the next generation of transportation systems [3; 23; 28; 29]. On the other hand, vehicular VLC systems face several challenges that are fundamentally different from outdoor applications, including the common absence of the line of sight in outdoor applications as a result of reflections from buildings, roads, and streets, in addition to weather conditions (such as rain, snow, and fog) and the effects of artificial lighting and sunlight. Another significant effect is the varying intensity of LED lights,  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multicolumn{1}{c}{**Content Explored**} & **[18]** & **[19]** & **[20]** & **[21]** & **[22]** & **[23]** & **[24]** & **[25]** & **[26]** & **[27]** & \begin{tabular}{c} **This** \\ **Survey** \\ \end{tabular}