# A Survey of Vehicular VLC Methodologies
## 1 Introduction  
Vehicular communication is one of the most critical technologies for the development of future intelligent transportation systems (ITSs) [1; 2]. Vehicular communication allows cars to exchange information with one another and the infrastructure along the road. For example, infrastructure-to-vehicle (I2V) connections can send extensive, valuable data to link automobiles. Additionally, the data are supplied over an I2V connection (such as the volume of traffic, alternate routes, facilities offered along the road, etc.) [3]. Furthermore, vehicle-to-vehicle (V2V) connections, such as forwarding brake-assist warnings and pre-crash monitoring, are crucial to safety. Radiofrequency (RF) technology has been commonly used in the majority of the research on vehicular communication [4; 5; 6]. For instance, the technique of dedicated short-range communication (DSRC) was implemented in [7], which offers a variety of applications, incorporating, among other things, automatic braking warnings and alerts for potential dangers at intersections. Furthermore, vehicular communications based on radio frequency (RF) face some limitations, such as the following: (i) the rate of received packets decreases due to road crowding, especially when there are massive vehicles; (ii) Intelligent Transportation Systems (ITSs) need improved reliability and, in particular, must address several security and safety risks [8; 9; 10]. Optical Wireless Communication (OWC) is one of the promising technologies for the new generation of wireless networks to overcome most of the problems facing traditional RF wireless communications. Moreover, visible light represents a part of OWC. Visible Light Communication (VLC) is a new wireless communication method that uses white light-emitting diodes (LEDs) to transmit information and illumination, which is a portion of the electromagnetic wave with a wavelength of 380-750 nm and a frequency range of 430-790 Hz, as shown in Figure 1. VLC technology has unique advantages over RF because its frequency range is safe for the human body and does not interfere with sensitive electronic devices. Moreover, its frequency range is not licensed because no laws restrict it. In addition, it offers free and massive bandwidth, and it is used for both communication and lighting purposes simultaneously. Another key advantage is that it is energy efficient because VLC uses LEDs (presenting small size as well as energy and cost savings) [11; 12]. VLC can be used for indoor or outdoor applications, depending on the application environment. Due to the term Li-Fi success [13], indoor VLC has gained more popularity and expansion. Furthermore, outdoor VLC has advanced more slowly due to the more challenging environment and other limitations with regard to mobility, weather, and legislation; it has nonetheless produced significant results. ITS is currently one of VLC's most potential outdoor applications. Therefore, vehicular networking applications can use the infrastructure for transportation and illumination with LEDs [14,15]. In the context of vehicular technology, all sorts of vehicle-to-everything (V2X), vehicle-to-vehicle (V2V), and vehicle-to-infrastructure (V2I) connections have become suitable to work with VLC due to the widespread use of LEDs in most infrastructure and traffic lights as well as vehicle headlights (HLs) and taillights (TLs) [16,17]. Due to the numerous features described above, VLC technology has greatly interested researchers in both practical and theoretical scenarios, as highlighted by several surveys conducted over the past few years. For example, the authors of [18] presented a comprehensive study on visible light communication, discussing significant challenges and concepts of VLC. Their study focused on the communication architecture of transmitter-receivers, standardization efforts, physical and MAC layers, processing time, and energy efficiency in VLC. In [19], the investigation centered around VLC applications and its historical development.