# Mono Camera-Based Optical Vehicular Communication for an Advanced Driver Assistance System
## 1 Introduction  
Vehicle navigation systems first drew attention in the late 1960s in the United States. The related primary goals included reducing highway congestion, increasing fuel efficiency, guiding routes, avoiding vehicle collisions, and collecting tolls electronically [1]. Nowadays, advanced driver-assistance systems are being extensively researched to reduce the number of casualties due to road accidents. Vehicle positioning and vehicle to vehicle (V2V) communication have immense potential to reduce the number of road accidents, making it possible to save the lives of a significant number of people by providing nearby vehicular position information to drivers. In particular, an intelligent transportation system requires precise vehicle positioning to ensure a safe braking distance from surrounding vehicles. The selection of appropriate technology is a challenging task as the vehicular density is high in metropolitan areas. Using radio frequency (RF)-based technologies, the system performance is expected to degrade owing to the huge amount of electromagnetic interference. Moreover, regular long-term involvement with RF can lead to adverse effects on drivers' health [2; 3; 4]. With the exponential growth of connected devices in 5G, which is supposedto become a more complex scenario in 6G, a visible light spectrum with bandwidth over thousands of times that of RF has attracted much interest from researchers. Nowadays, most vehicles are equipped with one or more cameras to assist in driving and parking, and daytime-running lights to draw the attention of other road users. The main objective is to ensure safety and a better driving experience by providing views of blind spots. Optical camera communication (OCC) can take advantage of the built-in light-emitting diodes (LEDs) as a transmitter and the camera as a receiver [5; 6]. Other key advantages of OCC technology include nearly interference-free communication and an unlicensed spectrum that can be used as a complement for the nearly saturated RF spectrum [7]. In a V2V communication scenario, the signal-to-noise ratio (SNR) is high, as the LEDs used for lighting have very high luminance. It offers a very strong line-of-sight (LOS) link set up at a long distance with a low bit error rate. Additionally, the effect of sunlight, a major challenge for other optical wireless communication systems in outdoor environments, can be effectively eliminated. Despite the high-speed switching capability of LEDs, the data rate of OCC systems is predominantly limited by the camera frame rate. Therefore, the significant advantages of OCC are often overshadowed by its low data rate. Researchers have already proposed a high-speed camera and multiple-input multiple-output technique [8; 9; 10] using an LED array to increase the data rate to one suitable for sensor data monitoring [11], patient monitoring [12], vehicular communication [13], and other low-rate indoor and outdoor applications [14; 15]. At present, the global positioning system is considered one of the most effective solutions for automobile navigation systems. It requires signals from a minimum of four satellites for a particular time to determine its three-dimensional (3D) location information. However, it faces significant challenges when the high-frequency signal is blocked by solid objects, such as terrains, subways, towering buildings, and trees. Additionally, it provides self-localization information but cannot measure inter-vehicle distance [1]. Radio detection and ranging (RADAR) is another potential candidate for inter-vehicle distance measurement that suffers from low localization estimation accuracy in the lateral direction, as it measures the angle of an object from the phase difference of multiple antennas. Frequency-modulated continuous-wave RADAR measures the distance and velocity of the forwarding vehicles (FWV) by transmitting a continuous-wave and analyzing the frequency variation between the transmitted and received waves [16].