# Simulation of an Indoor Visible Light Communication System Using Optisystem
## 1 Introduction  
With the development of the photophone, a device that transmits a voice signal on a beam of light, [PERSON] introduced the idea of using light as a communication medium in 1880 [1]. [PERSON] focused sunlight with a mirror and then talked into a mechanism that vibrated the mirror. At the other end, the detector captured the vibrating beam and converted it back into the voice signal. [PERSON] could not produce a helpful carrier frequency for transferring the light beam from one location to another; hence, his tests failed. [PERSON] had to cease his studies since the laboratory area's sunlight, fog, and rain interfered with his research. The Morse code transmission [2] in 1844 also gave rise to the concept of visible light communication. In Morse code transmission, it transmits text as a series of on-off tones, lights, or clicks that a skilled listener or observer can only understand. After that, the concept of visible-light communication (VLC) was revived by the developmentof LEDs in 1927. VLC uses white light-emitting diodes to transmit data by flashing light at speeds that are invisible to human eyes [3]. One important benefit of VLC is that it offers high-speed connection and can be utilized anywhere without distortion [4]. In the VLC system, LED is the transmitter, and a photodiode or phototransistor acts as the detector. The transmission medium used in the VLC system is the electromagnetic radiation spectrum (400 to 700 nanometers) visible to the human eye [5]. The unique characteristic of the VLC system is that it has no interference with radio frequency (RF) signals. Furthermore, secure communication, simple implementation procedures, and license-free band characteristics also enhance the usage of the VLC system for various applications [6]. The application of the VLC system includes Li-Fi [7], location-based services (LBS) [8], vehicle-to-vehicle communication [9], information displayed on sign boards [10], robots in hospitals (HOSPI) [11], augmented reality (AR) [12], and underwater communication (UTROV) [13]. When developing a VLC system, numerous factors must be considered, such as high data rates, uplink problems, legal considerations, LOS/NLOS situations, range (the separation between transmitter and receiver), and interference [14]. When we implement a VLC system, it is vital to optimizing these parameters because they control the system's performance. The transmitter (LED) and receiver (photodiode or phototransistor) for a high data rate-based VLC system must be compatible with their respective operating frequencies without affecting the system's cost. It is challenging and expensive to design a high data rate-based VLC system. This study examines the relationship between data rate, delay spread, and signal distortion using a VLC system simulation model. Several reflection pathways were considered in this study based on the number of LEDs employed as the transmitter. To examine how the simulated VLC system performed under LOS/NLOS channel conditions, we used an Optisystem simulation tool [15, 16]. This paper aims to analyze and understand the existing VLC systems and investigate the possibilities of improving the system's performance in a multireflection environment. We used an Optisystem simulation tool that simulated multiple reflection VLC systems using single and dual LEDs as transmitters. We started our simulation by considering the LOS propagation model that includes a direct path between the transmitter and receiver using a single LED and photodiode. Then, we extended our simulation in an NLOS propagation model by considering single and dual LEDs as its transmitters. After that, we estimated the data rate (Rb) using the root mean square (RMS) delay spread. When the data rate is assessed, we analyze the impact of the field of view (FOV) for data rate estimation. The essential contributions from our VLC simulations are summarised as follows. * We simulated a VLC system using the Optisystem simulation tool.