## 1 Introduction  
Currently, we encounter the Internet of Things (IoT) system frequently in our everyday lives, such as in smart homes, e-health systems, traffic monitoring systems, smart grids, and smart factories [1]. With the IoT system, devices can quickly join the IoT network through applied internet protocols [2]. The IoT system includes module devices, microcontroller units, plants, animals, and humans. It is designed to automatically connect people worldwide to the IoT network, which can result in a lack of human interaction. The IoT has played a significant role in the fourth industrial revolution; it helps people around the world to easily connect to one another. The wireless communication techniques upon which the IoT depends include radio frequency (RF) waveforms like LoRa, ZigBee, WiFi, and Sigfox. Furthermore, the negative effects that RF waveforms have on human health must be considered [3], especially in hospitals, schools, and other places where there are older people, children, and patients. Because of the harmful effect of RF systems, several researchers are assessing new suitable alternative technology. The use of visible light to transmit data, i.e., optical wireless communication (OWC), has emerged as a promising candidate to replace RF techniques. There are three possible techniques that can be used in OWC: visible light communication (VLC), light fidelity (LiFi), and optical camera communication (OCC). In LiFi and VLC, photodiodes use as the detectors that receive the intensity of light-emitting diodes (LEDs). Unlike LiFi and VLC, in OCC, image sensors serve as the detectors that receive data. Global shutter cameras and rolling shutter cameras, two popular camera types, are used in OCC systems [4]. Based on the type of camera, suitable OCC modulation schemes can be designed. The benefits of OWC compared with those of RF are presented below:  
* RF waves are commonly used in communication and have ubiquitous advantages, but it has two significant drawbacks: its impact on human health; and the influence of electromagnetic interference (EMI) on system performance. On the contrary, visible light waves do not have any known impact on human health [5]. * It is highly important to consider safety and effectiveness when the channel model achieves line-of-sight transmission. * The bandwidth of a visible light wave is more than 1000 times the bandwidth of Radiofrequency. With these potentials, numerous companies have funded research to develop and improve OWC technologies. In IEEE 802.15.7-2011 standard [6], the OWC techniques wewere introduced with its complexity protocol in 2011 only depend on VLC mode. The IEEE 802.15.7-2018 [7] is published, which amend the previous standard. In IEEE 802.15.7-2018, the OWC technique is amended with the following four modes:  
* The IEEE 802.15.7-2011 standard already provides detailed information about VLC modes [6]. * OCC: Modulation schemes can receive data from a variety of light sources using image sensors or cameras. * High-speed LiFi: The data rate is significantly improved to achieve more than 1 Mbps at the physical layer using high-rate photodiode modulation schemes. * LED identification: It mentioned communication schemes that use photodiodes to transmit data at a low data rate (below 1 Mbps). Owing to innovative manufacturing techniques, LEDs have the potential to become next-generation lights due to several advantages, such as long life, efficient power consumption, and many different modes and sizes. Besides that, one characteristic that makes LEDs useful for OWC technologies is the fast switchability [7; 8], which enables a high-rate OWC system. RF systems currently have numerous applications, such as communication, monitoring, and radar systems. Notwithstanding these applications, RF generates electromagnetic interference, affecting human health and brand function [9; 10]. OWC techniques have gained attention because they are EMI-free and thus will likely replace the RF technique [11] in the future.