# The Concept regarding Vehicular Communications Based on Visible Light Communication and the IoT
## 2 Methodology and Design Parameters  
Based on experience in the field of optical communication, research groups have consistently focused on adding new functions and generating related applications for VLC, including in relation to the IoT and vehicular communication. Several papers have discussed the use of VLC as part of various wireless technologies, but very few have focused on the IoT and road safety applications. In [21], architectures were proposed for VLC systems employing the IoT and its integration in the dark, using orthogonal frequency division modulation (OFDM) to overcome the identified limits [22]. In [23], VLC-over-UART-type systems were proposed that used the bit error rate and system evaluation. Another research paper [24] elucidated the potential of Li-Fi and its capacity for use in outdoor lighting, stating that it may represent a new backbone in the field of wireless communications. The activation of 5G wireless access using Li-Fi technology was addressed in [25] based on OFDM, demonstrating speeds of 200-300 kbps. Many of the challenges related to VLC, as well as the potential it has for industrial applications, were presented in [26], along with other concepts. Another review can be found in [27] that discusses various aspects and contributions, as well as providing an ensemble presentation, including aspects related to the optical IoT (OIoT). One new approach in V2V technology is the use of light fidelity (Li-Fi), which is an alternative medium in data transmission. The capacity of this technology to send data over an optical medium wirelessly using light-emitting diodes that propagate the signal makes it very promising. In the case of Li-Fi technology, data are extracted from the vehicle and spread via headlights or stoplights to other traffic participants or infrastructure, but there are many challenges related to bandwidth and data latencies. As shown in Figure 2, Li-Fi systems are composed of luminous media (LEDs) that transmit data and information, and the receiving system is based on a photo-detector that processes the data and analyzes the obtained signal. It is imperative to implement systems of this type because the actions that traffic participants take are based on information obtained from other vehicles and involve short durations of time and extremely low-validity data. Thus, in the case of systems of this type, GPS and Wi-Fi units are not necessary because Li-Fi technology can use interface or PIC controllers to emit tiny pulses of sound, which can penetrate barriers and be employed with straight roads or those of the T-junction type [24]. V2V technology can accurately calculate the moment T of a collision and highlight its severity when used synchronously with a laser detector or laser rangefinder (LRF). The guarantee that this is a highly viable system comes from the accumulation of adjustable vehicle functions, which can allow the generation of protocols and procedures to expedite the activation of pre-crash systems or airbags even before collisions occur [28]. Communication between vehicles is dependent on the distance of the convergence or divergence between them because the density of cars on roads is involved in the first process of the information transmission mechanism. In the case of congested roads where the traffic density shortens the distance between vehicles, the communication process takes place in a platoon-type network with vehicles separated by small distances, and hybrid implementation of VLC-RF is necessary [29]. In the case of visible light, data can be transmitted with a single data-stream instance extremely quickly [30]. In addition to what has been presented above, there are also aspects of the topic related to the exploitation of THz bands dedicated to vehicular networks, which have intrinsic properties. As millimeter-wave technology moves toward  
Figure 2: Illustration regarding the fields of communication within VANETs. commercial implementation, it is clear that the terahertz (THz) band is the next frontier of communications.