Visible Light Communication (VLC) is a novel optical wireless communication technology which uses Light Emitting Diodes (LEDs) and Photodiodes for coherent detection and very-high-data rate data communication system. The stringent Line of Sight (LoS) requirement in VLC makes it very suitable for Indoor Positioning System (IPS), to be used for autonomous and smart city infrastructure. The current work aims to implement a real time IPS system using VLC link in Network Simulator (NS-3). The VLC module is implemented by modelling real-time attributes of LEDs, optical channel, and the photodiodes. The localization is carried out using trilateration schemes which measures the Received Signal Strength Indication (RSSI) and the Time Difference of Arrival (TDoA) for position estimation of the target. The project is further extended to obtain a comparative analysis between VLC link and other existing technology, Wi-Fi, as far as positioning accuracy and other important performance metrics are concerned. The simulation results show significant improvement for the VLC link over the Wi-Fi link specially for the TDoA scheme accompanied by increasing number of beacon nodes. INDEX TERMSVisible Light communication, IPS, RSSI, TDoA, Trilateration or Multilateration, NS-3 simulator. I. INTRODUCTION Since the inception of RF technologies, there has been a tremendous growth in the telecommunication sector, especially the wireless networks. However, with the increase in demand of RF spectrum, RF spectrum saturation has been observed. The interference between the communication links has also taken a toll [1]. Due to this dilemma, optical communication technologies, i.e., non-RF spectrum technologies, have gained considerable attention of data communication researchers. Amongst optical communication technologies, VLC is relatively a recent data communication that offer extremely high data rate and inherent security [2]. This is because the VLC provides the best of the transmission characteristics with the minimum trade-off. Other salient features include non-penetration to walls, cost effectiveness, vast spectrum of communication, no interference with RF spectrum (430-790THz), and high resolution for localization applications [3]. The communication over a VLC link is highly secure for covert communication due to opacity hindrance because VLC signal cannot pass through walls and other opaque materials.The high transmission speed, safety, low energy consumptions and operating in restricting environments, all provide an edge to VLC over the standard Wireless communication technologies [4]. It is worth-mentioning that although VLC links are very reliable due to the noninterference of RF signals, yet Low Density Parity Check (LDPC) codes are, in general, able to achieve the capacityapproaching performance of a myriad of communication systems. However, the present work does not take into consideration the use of LDPC codes due to the scope of the work [5,6]. The VLC systems use LEDs to transmit wireless data over long distances and support su...

Visible light communication (VLC) is the branch of optical wireless communi-cations that uses light-emitting diodes for the dual purpose of illumination and very-high-speed data communication. The main motivation behind the current work is finding alternatives to the saturated radio frequency spectrum, radio frequency security issue, and vulnerability to interferences. The current work is aimed at developing a module for the physical layer of a VLC-based ad hoc network in network simulation 3. The VLC physical layer module is developed by using the optical signal modules available in the network simulator.The work also includes modelling of VLC-based transmitter, wireless optical channel, and the optical receiver. Furthermore, the implementation and evaluation of the VLC-based physical layer is carried out over a typical ad hoc network under different performance metrics. The designed ad hoc network is also tested under Wi-Fi module followed by its comparison with corresponding ad hoc network under VLC module. The comparison is based on bit error rate curves, system throughput, and gain in received signal-to-noise ratio mainly.Finally, the suitability of different modulation schemes is also investigated in the current work for both Wi-Fi-and VLC-based ad hoc networks. KEYWORDS ad hoc networks, bit error rate (BER), Li-Fi, modulation SCHEMES, network simulator, NS3, OOK, PAM, PHY layer, throughput, visible light communication (VLC), VPPM, 5G mobile communication | INTRODUCTIONIn the past decade, there has been a drastic increase in the demand for high-speed data communication services (cellular networks, smart TVs, cloud-based computing, high-definition video calling, and live streaming). The existing radio frequency (RF) wireless technologies have been the forefront of telecommunication, revolutionizing the voice and data communication. 1 However, because of saturation of RF spectrum, security issues, vulnerability to interferences, and hazards of RF, low-cost and reliable technologies are required to provide efficient data communication. The discovery and growing use of light-emitting diodes (LEDs) have boosted the research in visible light communication (VLC) technology. 2 Visible light communication is becoming an emerging green technology aimed to providing high data rates for short-range communication and easy deployment in hospitals, planes, and areas where traditional RF systems are less preferred. 3 The VLC salient features include license and interference-free spectrum (430THz-790THz), extremely large bandwidth, inherent security, compatibility with existing technologies, and high efficiency for positioning purposes due to its line-of-sight (LoS) feature. 4

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