Abstract—Over the years, more and more conventional lighting systems tend to be replaced by LED lighting systems because of their advantages such as high energy efficiency, longer lifespan and lower heat generation. Because of the LEDs’ capability of switching to different light intensities at fast rate, these lighting solutions could be used for both illumination and transferring data. This characteristic of the LEDs has led to the development of a new technology, known as Visible Light Communication (VLC). In this type of communication, the receiver is usually a photodetector. Lately, the tendency is to also use video cameras to receive the transmitted data. Solutions exist, but they use expensive cameras that can capture over 800 frames per second (fps). The communication proposed in the paper uses a LED as a transmitter and a camera with a common frame rate (120 fps) as the receiver. At those frame rates the challenge is to use a code that avoids flickering and does not need a synchronization between the transmitter and the receiver. A version for such code is also presented in the paper. The system was implemented and tested. The results confirm the functioning of the proposed low frame rate VLC communication system. Index Terms— Visible Light Communication, Camera Receiver, CMOS Image Sensor, Low Frame Rate Camera. I. INTRODUCTION HE VLC is an optical wireless communication that uses the visible light source (in our case, LEDs) as a transmitter and typically a photodetector (i.e., photodiode, phototransistor etc.) or an image sensor as the receiver [1]. By changing the light intensity of the LEDs, we can transfer data, but this changing must be very fast to prevent the effect of flickering. There are several advantages of the VLC system compared to the classic radio communication system: more energy efficient, by using light instead of radio waves, more The activities presented in this paper were performed in the frame of two programs: Project PN - III - P1-1.2-PCCDI-2017-0560, “Eco-nano- technologies and smart equipment for mapping the soil parameters and plant growth dynamics in order to increase the efficiency of agricultural production and environmental protection - ENI”, under contract no. 41PCCDI/2018, and respectively Project PN-III-P1-1.2-PCCDI-2017-0419, “Sensors and electronic and photonic integrated systems for the security of people and infrastructures - SENSIS”, under contract no. 71PCCDI 2018. A. E. Marcu is with the Electronic Technology and Reliability Department, “Politehnica” University of Bucharest, Bucharest, Romania (e-mail: alina_elena.marcu@upb.ro). R. A. Dobre is with the Telecommunications Department, “Politehnica” University of Bucharest, Bucharest, Romania (e-mail: rdobre@elcom.pub.ro). M. Vlădescu is with the Optoelectronics Research Center (UPB-CCO), “Politehnica” University of Bucharest, Bucharest, Romania (e-mail: marian.vladescu@upb.ro). secure compared to the radio waves who creates electromagnetic interferences and can be dangerous in hazardous operations [2]. As a disadvantage, the communication requires a permanent line-of-sight clearance between the transmitter and the receiver. There are a variety of applications in which VLC can be used, for example in aviation, where it can be used to provide media services for passengers, in hospitals, where can be used where the medical equipment can interference with the radio waves, and in underwater wireless communications. An application in which VLC has a key role is the automotive communication. With the continuous development of the autonomous cars, the current road infrastructure system can be improved using VLC to provide a safe road traffic. The vehicle communication systems [3] can be divided in two subsystems: vehicle-to-vehicle (V2V) and vehicle-to- infrastructure (V2I). An important application of the V2I system could be the possibility that the car could communicate with the traffic signaling system. An example could be the automatic braking of the vehicle in case of the red lights and an audio warning in the case of yellow lights [4], thereby reducing the red lights crossing rate and increasing the traffic safety. In V2V systems, the vehicle headlights and taillights could be used to transmit messages about the current state of the car, hard brake warnings to the surrounding cars. An application that uses the V2V and V2I systems simultaneously is the Intelligent Transportation System (ITS) [5], who collects the traffic data from the systems, analyses it, and based on the given results it automatically adjusts the road system to the situation. The advantage of the ITS is that the traffic is monitored continuously, and in case of a traffic congestion, the traffic lights can adjust automatically to ease the traffic, increasing the efficiency and in case of an accident, the traffic lights can turn green to ease the access of the emergency vehicles. In the automotive applications, a modern approach in developing a VLC system is by using a CMOS image sensor [6] as a receiver. An advantage of the CMOS image sensor receiver is the possibility to receive multiple transmitted data by LEDs modulated individually [7]. Another advantage of using an image sensor as a receiver is the possibility to communicate with different transmitters. For example, the VLC system can receive simultaneously the information from the traffic signaling lights and from the taillights of the vehicle ahead. Because the possibility to separate the data that comes from multiple sources (e.g., the data from the LED itself, the data from the ambient light), the image sensor receiver can be Flicker Free Visible Light Communication Using Low Frame Rate Camera Alina E. Marcu, Robert A. Dobre, and Marian Vlădescu T