Time Difference of Arrival Based Indoor Positioning System Using Visible Light Communication

Abstract

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...

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