Faculty Publications
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Publications by NITK Faculty
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Item Design, Implementation, and Evaluation of a Low-Cost Visible Light Communication Testbed(Springer Science and Business Media Deutschland GmbH, 2024) Salvi, S.; Geetha, V.The proposed testbed demonstrated and studied the behavior of channels and modulation techniques. Modulation techniques such as On-Off Keying (OOK) and Pulse Duration Modulation (PDM) were implemented on the testbed. Their performance was evaluated based on the distance between the transmitter and receiver, bit rate, and accuracy. A free-space optical communication channel model was also implemented in MATLAB to study the impact of physical characteristics on channel performance. Physical factors such as room dimensions, LED power, and transmitter field of view (FoV) were considered for the simulation. Additionally, the results of the proposed testbed were compared with the standard indoor free-space optical communication channel model implemented in MATLAB. It was observed that the PDM modulation technique consistently provided a 2x improvement in accuracy over OOK modulation for the same distance. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.Item Li-Fi for Secured Access to Wireless Network During Online Examination in Classrooms(Springer Science and Business Media Deutschland GmbH, 2024) Salvi, S.; Apune, S.; Gutte, V.; Gawade, M.; Kolkar, R.The traditional conduction of examinations needs to use physical copies of question paper and answer sheets, which are then evaluated by the evaluators. However, in a post-pandemic era, where the emphasis is more on the minimal usage of physically transferable materials, safe conduction of examinations in the classroom environments becomes challenging. Conduction of examination in complete online mode requires wireless access to the Wi-Fi access points; however, as the range of the Wi-Fi access point goes beyond the classrooms, there is the possibility of accessing the network from outside classroom which is not desired. With an aim to address these issues, in this paper a novel approach for providing dynamically changing passwords using visible light communication is designed, implemented and tested for connecting to the wireless network. The setup is useful in the environment where restricted physical access is needed to ensure system and network security. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.Item Design of Collision Detection System for Smart Car Using Li-Fi and Ultrasonic Sensor(Institute of Electrical and Electronics Engineers Inc., 2018) Krishnan, K.The 21st century is defined as the era of technological development. With drastic increase in population, automation is becoming the need of the hour in order to make life more comfortable and easy. Due to the advancement and development in the field of automation and embedded system, the notion of smart car has become very popular. Smart cars are modernizing trends in the traditional automobile industry. Companies across the globe have been investing a huge amount of resources on the production and design of smart cars. Every technological development needs to overcome certain obstacles, and hence, in this paper, a design of a collision detection system for smart car using light fidelity (Li-Fi) and ultrasonic sensor on the Arduino platform is proposed. This design consists of an ultrasonic sensor, an Arduino processor, and a Li-Fi circuit. The ultrasonic is used for measurement of distance between vehicles, and Arduino processes the data and makes decisions accordingly. Data transmission between vehicles is ensued using a Li-Fi transmitter circuit and a Li-Fi receiver circuit. The transmitter circuit is mounted on the tail lights of the leading car and the receiver circuit is mounted on the front side of the car that follows. Using visible light communication, the transmitter circuit transmits the calculated speed and the information is received by the receiver circuit of the second car. On the basis of the information received, the speed of the second car is changed in order to avoid collision. In this paper, a system that can detect and thus avoid collision between vehicles and prevent accidents is proposed and studied. © 1967-2012 IEEE.Item BER analysis of a full-duplex relay-assisted BPSK-SIM based VLC system for indoor applications(Optica Publishing Group (formerly OSA), 2023) Bhargava Kumar, L.B.; Naik, R.P.; Choudhari, D.; Krishnan, P.; G.D., G.D.G.; Jagadeesh, V.K.This paper contemplates a relay-assisted visible light communication (VLC) system, where the light source (table lamp) acts as a relay node and cooperates with the main light source. Following the IEEE 802.15.7r1 VLC reference channel model, we assume that there are two different light sources present in an office room. The first one is the source terminal present on the ceiling and another one is the desk lamp that serves as the relay station, which works in a full-duplex method. Because of the loop interference channel, we model the VLC relay terminal using ray tracing simulations. We have analyzed the bit error rate (BER) performance of the relay-assisted VLC system using a binary phase shift keying–subcarrier intensity modulation (BPSK-SIM) technique. The proposed method outperforms existing phase shift keying (PSK) and square M-quadrature amplitude modulation (M-QAM) techniques. The proposed VLC system using the BPSK-SIM technique achieves a BER performance of 10−12 for an SNR of 20 dB. The results of the proposed full-duplex and half-duplex relayed VLC systems are evaluated using equal power allocation (EPA) and optimum power allocation (OPA) techniques over three different modulation schemes, which are 2-PSK, square M-QAM, and BPSK-SIM. © 2023 Optica Publishing Group.Item All-Optical UAV-Based Triple-Hop FSO-FSO-VLC Cooperative System for High-Speed Broadband Internet Access in High-Speed Trains(Institute of Electrical and Electronics Engineers Inc., 2023) Aarthi, A.; Bhargava Kumar, L.B.; Krishnan, P.; Natarajan, R.; Jayakody, D.N.K.In this paper, we proposed an unmanned aerial vehicle (UAV) based all optical triple hop mixed free space optical-free space optical-visible light communication (FSO-FSO-VLC) system for broadband internet access in high-speed train applications. The system consists of triple hops from gateway to the UAV, UAV to train and train to the end user. Two decode and forward relays are mounted on the UAV and train respectively to transmit the data between the gateway to the end-users. The first hop between gateway to UAV consist of FSO link which follows M-distribution. The second hop between the UAV to train consists of FSO link and is modelled using Gamma-Gamma distribution which takes into account both atmospheric turbulence and pointing errors due to position/orientation deviation. The third hop between the train and end user is connected using VLC link and it is mathematically modelled using Lambertian emission distribution. The relays map the incoming signal on the FSO links and send it down to the user inside the train via the VLC downlink. We derived the closed form expressions for average bit error rate and outage probability of the proposed system. This paper investigates the effects of atmospheric turbulence, field of view, beam divergence angle, displacement deviation variance, optical concentrator gain, number of access point, and modulation schemes on system performance. First time, we proposed all-optical system which offers high data rate and low transmission delay. © 2013 IEEE.