Li-Fi Communication Research Articles

Enhancing the performance of LiFi communication with OSTBC, QAM, and OFDM: High-capacity, low-complexity transceiver design

Light fidelity (LiFi) is one of the most promising areas within wireless optical communication system. It provides many benefits, including high capacity, improved security and enhanced cost-effectiveness. However, there is still challenges which are link blockages, attenuation, interference and bandwidth restriction of modulation techniques. Orthogonal space–time block coding (OSTBC) offers a suitable solution to address link blockage by providing an alternative communication channel between the transmitter and the receiver. OSTBC has more tolerate to the practical channel impact limitation such as attenuation and interference that may occur in overlapping regions. In addition, the use of the OSTBC technique enhances the system’s ability to transfer data as the transmission rate is duplicated by the number of transmitters and receivers. This paper proposes the utilisation of a LiFi transceiver-based OSTBC that employs quadrature amplitude modulation (QAM) in conjunction with orthogonal frequency-division multiplexing (OFDM). Co-simulation tools have been done by integrated Matlab with Optisystem, were used in the design of LiFi transceiver with all assumption required. The findings reveal the capability of LiFi transceiver of transmitting rate up to 15 Gbps with maintaining a satisfactory bit error rate (BER) of 10−4 over a link range of 200 m evenin the presence of realistic channel effects. Moreover, the LiFi transceiver’s structure used does not incorporate optical amplifier components, resulting in reduced computational complexity compared to conventional LiFi transceivers. The proposed system proved its progress over the previous work under the influence of the same input effects.

Deployment of a UAV swarm-based LiFi network in the obstacle-ridden environment: algorithms of finding the path for UAV placement

The subject of this study is unmanned aerial vehicle (UAV)-based wireless networks in an obstacle-ridden environment. The aim of this study is to develop methods and software to ensure reliable LiFi communication using swarm UAVs in an obstacle-ridden environment. The objectives are as follows: 1) to describe the problem of providing a reliable UAV swarm-based LiFi network, requirements for the composition and use of UAVs, and assumptions; 2) to develop the methodology for solving research tasks; 3) to develop the method and algorithms for solving the problem, considering the requirements, assumptions, and practical limitations; 4) to explore the algorithms by developing software for modeling and searching for rational UAV placement to ensure the required UAV-based LiFi network characteristics; 5) to provide experiments and illustrative examples of the developed tool’s application. The following results were obtained. 1) The requirements for the composition and use of UAVs for creating LiFi networks, as well as assumptions and limitations for the methodology development and research task solving. 2) An obstacle avoidance method using the left and right angles algorithm. 3) A method for obstacle avoidance using the controlled waterfall algorithm. 4) A software tool for modeling and searching for rational UAV placement to ensure the required LiFi network characteristics. The tool allows route construction under obstacles in 2D space and a comparison of the developed algorithms for various variants of obstacle placement. Conclusions. The main contribution of this research is a set of methods, algorithms, and software tools for providing communications between two points using LiFi technologies and a swarm of UAVs supporting these communications as transmitters in conditions of mechanical obstacles.

Transfer learning for resource allotment in dynamic hybrid WiFi/ LiFi communication systems

The demand of newer technologies for fifth generation mobile communication systems is high in the current arena. A hybrid form of Free Space Optical (FSO) Communication, also called Light Fidelity (LiFi) Communication, and Wireless Fidelity (WiFi) Communication technologies, has emerged as a promising candidate to fulfill it. Such a system is termed as hybrid WiFi/LiFi Communication System. The joint optimization problem of bandwidth, user association and power for data rate maximization in these hybrid systems is non-concave. Deep Q Network (DQN) Learning based algorithms offer solution to non-concavity. However, existing DQN learning based solutions are often restricted to static networks. They face complexity issues in dynamic networks. In this paper, we address the dynamic hybrid WiFi/LiFi Communication system with DQN transfer learning algorithm. Transfer learning is used to gather information about a newly entering mobile user in the network, thereby improving the overall throughput of the network. Simulations show that the proposed algorithms perform well than the existing optimization algorithms in throughput maximization.

Improved LED arrangement through outage probability minimization in LiFi communication systems

AbstractIn this paper, an improved method to arrange the light emitting diodes (LED) on the ceiling for an indoor visible light communication (VLC) system is proposed. More precisely, a LiFi‐based connection is considered where several LEDs are placed on the ceiling of an office and communicate with several receiver (user) located randomly within the room area. It is proposed to find the optimal location of the LEDs by minimizing the outage probability at the user's location. Both cases of static and mobile users are addressed. First, the closed‐form expression for the outage probability at the user's location is derived. Then, by minimizing the average outage probability, the optimal location of the LEDs is found. The numerical results show that the proposed LED arrangement outperforms the classically used uniform LED arrangement in terms of average outage probability at the receiver and reduces the necessary signal‐to‐noise ratio (SNR) to achieve a target average outage probability by about 3 and 2.2 dB for mobile and static users, respectively. They also show that the performance superiority of the proposed method over classical arrangement remains valid even under large estimation errors.

IoT implementation of underwater communication using Li-Fi

Li-Fi is similar to wireless communication which uses the communication medium as light. Nowadays RF interference are getting common due to maximum utility to overcome this problem Li-Fi is introduced in the year 2011. Li-Fi uses LED source to transmit data wirelessly this method is widely called as VLC (visible light communication). IoT technology using light fidelity module plays a vital role in environmental monitoring, underwater disaster management and underwater military applications. Li-Fi communication provides data rate of more than hundreds of Mbps for short ranges and it is an alternative approach to accostic communication in underwater. In Li-Fi, light emitting diode (LED) lamps acts as access points (Aps), and light is used as a medium to carry information bits. At the receiver, a photo diode is employed to collect photons and convert them into a electric current. By using Li-Fi technique, data is transmitted in the light. Photo detector absorbs the light and convert it into electrical signal. The photo detector is placed near the surface of the sea. The information is then passed to cloud storage then it is utilized for various application.

Lasing Action from Quasi-Propagating Modes.

Band edges at the high symmetry points in reciprocal space of periodic structures hold special interest in materials engineering for their high density of states. In optical metamaterials, standing waves found at these points have facilitated lasing, bound-states-in-the-continuum, and Bose-Einstein condensation. However, because high symmetry points by definition are localized, properties associated with them are limited to specific energies and wavevectors. Conversely, quasi-propagating modes along the high symmetry directions are predicted to enable similar phenomena over a continuum of energies and wavevectors. Here, quasi-propagating modes in 2D nanoparticle lattices are shown to support lasing action over a continuous range of wavelengths and symmetry-determined directions from a single device. Using lead halide perovskite nanocrystal films as gain materials, lasing is achieved from waveguide-surface lattice resonance (W-SLR) modes that can be decomposed into propagating waves along high symmetry directions, and standing waves in the orthogonal direction that provide optical feedback. The characteristics of the lasing beams are analyzed using an analytical 3D model that describes diffracted light in 2D lattices. Demonstrations of lasing across different wavelengths and lattice designs highlight how quasi-propagating modes offer possibilities to engineer chromatic multibeam emission important in hyperspectral 3D sensing, high-bandwidth Li-Fi communication, and laser projection displays.

LiFi- Future Technology

The introduction of Wi-Fi into the residences is creating a biological havoc among humans. A lot of research has been evolved and presented depicting the various imperfections caused by the radiation of Wi-Fi. To overcome this LiFi technology may be used for indoor communication instead of Wi-Fi. LiFi communication needs line of sight for communication. LiFi transfers the information through visible light. Light cannot travel through opaque objects. The various properties of light like Reflection, Refraction, scattering effects on visible light will lead to data loss. Hence LiFi is preferably used indoors. This article discusses on the effects of biological degradation caused by Wi-Fi, Bluetooth etc. in short, this article enlists the effects of radio waves in accordance with the psychological changes caused in mankind. This in turn will lead to build a system which will also ensure the safety of the ecosystem for the development of mankind.

Employing light fidelity technology in health monitoring system

Light Fidelity (Li-Fi) is an emerging technology that has been in transferring data packets in Internet of Things (IoT) applications. During the COVID-19 pandemic, healthcare institutes try to manage the rapid increase of patients’ numbers. The healthcare team may not have the ability to monitor patients’ stats around the clock with the conventional techniques. In this paper, a healthcare monitoring framework to exchange health data between biosensors and terminals employing Li-Fi technology is proposed. It exploits Li-Fi to transmit data towards a terminal then to a cloud platform. It is intended for use in highly dense healthcare institutes where the number of patients is high. Exploiting Li-Fi to establish connection to cut high cost of other transmission technologies including Wi-Fi and provides less complexity and shorter latency. We evaluate the framework in a real-life environment using biosensors and Li-Fi communication model (for network infrastructure), these two components are connected to a computing terminal to help health staff monitor patients. The computing terminal is connected to a cloud platform to provide remote monitoring and computing resilience. The framework shows superior performance in real-world scenarios compared to Wi-Fi. A comprehensive analysis has been conducted to show the differences between Li-Fi and Wi-Fi.

Learning Indoor Environment for Effective LiFi Communications: Signal Detection and Resource Allocation

Seamless light fidelity (LiFi) communications in a realistic indoor environment faces a number of important challenges including the loss of line-of-sight (LOS) link due to the random orientation of mobile devices or blockage by users or furniture in the room. These effects make the frequency response of the LiFi channel highly environment-dependent. The dynamic nature of the channel is not only dependent on the geometrical configuration of the room but also on the user behavior. In this paper, we investigate the hypothesis that, deep learning (DL) based LiFi communication techniques can effectively learn the distinct features of the indoor environment and user behavior to provide superior performance compared to conventional channel estimation techniques particularly when access to real-time channel state information (CSI) is restricted. In particular, we implement DL methods in two different problems, namely, signal detection and resource allocation for orthogonal frequency division multiplexing (OFDM) LiFi systems. To effectively test this hypothesis, a realistic LiFi channel impaired by random device orientation and blockage is simulated considering different geometrical configurations and user behavior in an indoor environment, e.g. presence or lack of furniture and varying user distribution defined by a conditional hotspot model. The simulation results confirm that DL-based LiFi systems with partial CSI are able to offer close performance to the optimal signal detection and resource allocation with perfect CSI. Moreover, the DL-based techniques demonstrate substantial gain against conventional benchmark schemes that employ channel estimation algorithms such as least squares (LS) or minimum mean square error (MMSE) and this gain increases in a more realistic or complex indoor environment, e.g. room with furniture or a hotspot scenario.

Analyzing Li-Fi Communication Benefits Compared to Wi-Fi

Analyzing Li-Fi Communication Benefits Compared to Wi-Fi

LiFi Positioning for Industry 4.0

Precise position information is considered as the main enabler for the implementation of smart manufacturing systems in Industry 4.0. In this article, a time-of-flight based indoor positioning system for LiFi is presented based on the ITU - T recommendation G.9991. Our objective is to realize positioning by reusing already existing functions of the LiFi communication protocol which has been adopted by several vendors. Our positioning algorithm is based on a coarse timing measurement using the frame synchronization preamble, similar to the ranging, and a fine timing measurement using the channel estimation preamble. This approach works in various environments and it requires neither knowledge about the beam characteristics of transmitters and receivers nor the use of fingerprinting. The new algorithm is validated through both, simulations and experiments. Results in an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{1}\;{\rm{m}} \times \text{1}\;{\rm{m}} \times \text{2}\;{\rm{m}}$</tex-math></inline-formula> area indicate that G.9991-based positioning can reach an average distance error of a few centimeters in three dimension. Considering the common use of lighting in indoor environments and the availability of a mature optical wireless communication system using G.9991, the proposed LiFi positioning is a promising new feature that can be added to the existing protocols and enhance the capabilities of smart lighting systems further for the benefit of Industry 4.0.

Energy efficiency assessment of power electronic drivers and LED lamps in Li-Fi communication systems

Light-fidelity (Li-Fi) communication systems have gained increased concerns as new and alternative paradigm for wireless communications. Through the increased applications of light emitting diode (LED) lamps for lighting in indoor and outdoor applications, industrial and academic interests have been risen towards adding communication functionality to the standard light emitting diode lamp illumination functionality in light-fidelity systems. As being the same source for lighting and communication, extra power losses and stresses are imposed on the light emitting diode lamp and its power electronic drivers to perform the dual functionalities. Therefore, proper light emitting diode lamp driver design and control systems are required. This paper reviews the different architectures of light-fidelity communication systems and develops a powerful systematic approach for assessing the energy efficiency and the communication system performance metrics for light-fidelity systems. Various light-fidelity structures, communication modulators, power converters, and communication modulation methods are considered based on the mathematical modelling. Simulation results show that energy efficiency and communication system performance are largely affected by system architectures, components, and communication modulators. The obtained results show that the proposed method represents a systematic approach for calculating the energy efficiency and power losses for various elements in light-fidelity systems. Additionally, the calculated energy efficiency with adding the communication functionality is lower than the traditional illumination of the lamps. The type of modulation technique, type of modulator, modulation index value, and forward lamp current have substantial effects on the calculated energy efficiency.

Transfer Data from PC to PC Based on Li-Fi Communication Using Arduino

Light Fidelity (Li-Fi) is a new technology that has been developed in the last few years and still needs more investigation and experiments to prove its perfection to be an alternative solution for wireless fidelity (Wi-Fi) technology. Li-Fi utilizes light as a medium of communication instead of traditional radio frequencies as in Wi-Fi. Li-Fi technology has the essential features compared to Wi-Fi, such as its ideal for high-density wireless data coverage in a confined area and reducing radio interferences issues. In this paper, a PC-to-PC wireless data transfer system is proposed based on Li-Fi technology. Data is transmitted from transmitter Pc via the light of an array of high-power white LEDs connected to Arduino UNO. The data is then received on the PC receiver using a photodiode, connected to another Arduino UNO device, to sense the light and decode it to its original format. This work aims to improve the transmission and reception mechanism by increasing the data bit rate. After experimenting, the evaluation results showed that the data bit rate was improved using the proposed transmission mechanism and reached up to 147 bps with an accuracy of 100%, over 20 cm as a distance between the transmitter and receiver.

Forecasting of Energy Demands for Smart Home Applications

The utilization of energy is on the rise in current trends due to increasing consumptions by households. Smart buildings, on the other hand, aim to optimize energy, and hence, the aim of the study is to forecast the cost of energy consumption in smart buildings by effectively addressing the minimal energy consumption. However, smart buildings are restricted, with limited power access and capacity associated with Heating, Ventilation and Air Conditioning (HVAC) units. It further suffers from low communication capability due to device limitations. In this paper, a balanced deep learning architecture is used to offer solutions to address these constraints. The deep learning algorithm considers three constraints, such as a multi-objective optimization problem and a fitness function, to resolve the price management problem and high-level energy consumption in HVAC systems. The study analyzes and optimizes the consumption of power in smart buildings by the HVAC systems in terms of power loss, price management and reactive power. Experiments are conducted over various scenarios to check the integrity of the system over various smart buildings and in high-rise buildings. The results are compared in terms of various HVAC devices on various metrics and communication protocols, where the proposed system is considered more effective than other methods. The results of the Li-Fi communication protocols show improved results compared to the other communication protocols.

Compensating Dynamic Nonlinearities in LED Photon Emission to Enhance Optical Wireless Communication

LEDs can be modulated to support wireless optical data communication. However, particularly LEDs optimized for illumination act as a non-linear low-pass communication channel. In this paper, we translate the non-linear differential equations for the hole-electron recombination and photon emissions, into a discrete-time model with delay taps and non-linear coefficients. This LED model can be inverted, to actively eliminate or mitigate the non-linear dynamic LED distortion. We propose a further simplification of the compensation circuit that allows us to use a relatively simple structure with only a couple of parameters. We experimentally characterize and measure signals communicated via commercially available illumination LEDs that are also used for LiFi communication. In an Intensity Modulation Direct Detection (IM/DD) system employing Pulse Amplitude Modulation (PAM), we show that the proposed equalizer can effectively widen the measured eye diagram, thereby reduce the error rate or can allow a larger constellation. For Orthogonal Frequency Division Multiplexing (OFDM), the reduction in distortion allows at least a 50% increase in bit rate, even on measured noisy channels. This confirms the suitability of the LED model on which our non-linear equalizer is based. We show how non-linear time-constants can be estimated from electrical measurements on the LED signal. With the proposed parameter estimation, the equalizer converges to appropriate compensation settings, in Minimum Mean Square Error (MMSE) sense.

Remote Tracking Gas Molecular via the Standalone-Like Nanosensor-Based Tele-Monitoring System

HighlightsA standalone-like smart device that can remotely track the variation of air pollutants in a power-saving way is created;Metal–organic framework-derived hollow polyhedral ZnO was successfully synthesized, allowing the created smart device to be highly selective and to sensitively track the variation of NO2 concentration;A novel photoluminescence-enhanced Li-Fi telecommunication technique is proposed, offering the created smart device with the capability of long distance wireless communication.Remote tracking the variation of air quality in an effective way will be highly helpful to decrease the health risk of human short- and long-term exposures to air pollution. However, high power consumption and poor sensing performance remain the concerned issues, thereby limiting the scale-up in deploying air quality tracking networks. Herein, we report a standalone-like smart device that can remotely track the variation of air pollutants in a power-saving way. Brevity, the created smart device demonstrated satisfactory selectivity (against six kinds of representative exhaust gases or air pollutants), desirable response magnitude (164–100 ppm), and acceptable response/recovery rate (52.0/50.5 s), as well as linear response relationship to NO2. After aging for 2 weeks, the created device exhibited relatively stable sensing performance more than 3 months. Moreover, a photoluminescence-enhanced light fidelity (Li-Fi) telecommunication technique is proposed and the Li-Fi communication distance is significantly extended. Conclusively, our reported standalone-like smart device would sever as a powerful sensing platform to construct high-performance and low-power consumption air quality wireless sensor networks and to prevent air pollutant-induced diseases via a more effective and low-cost approach.

On-The-Move Measurement Analysis for Ka-Band High Throughput Satellite and LiFi Communication Networks in Tropical Region

With the point in evaluating the performance of the On-the-Move (OTM) Satellite Communication and Light Fidelity (SatCom-LiFi), an extensive study of measurement has been conducted to give a wide vision of the SatCom-LiFi potential under a tropical region. As the interest for OTM network connectivity to offload the C-band capacity arises due to frequency spectrum scarcity, satellite networks offer to balance topographical requirements under tropical environment as the Next Generation Networks (NGN) trend for OTM communication system solutions. To date, mobile satellite terminal propagation model was carried out at temperate regions where further experimental measurement is needed under the OTM scenario in tropical region. This paper discusses on the areas where there are limited real-time data under the OTM scenario (e.g. rain attenuation, power arch) at Ka-band frequency. Integration infers, to be specific, the use of new elements capable in providing performance analysis of all systems involved and to take possible decision, in determining the need for a technically feasible solution. Measurement results reveal that, throughput data rate of 15 Mbps were able to be delivered for more than 80% of the time under the speed of 150 km/h with shielded mesh antenna. In addition to that, this paper reveals the favorable circumstances and inadequacies of OTM network quality, in which the measurement presented plays an important role for future researchers in distinguishing highly accurate predictions.

Liquefied Petroleum Gas Leakage Detection And Alert System Using Li-Fi Technology

There is an ignorance prevailing among the people on home security these days. They intend it as just as surveillance technologies such as CCTV and other such security system. The security system besides keeping an eye as monitoring the vicinity, it should prevent the mishap. The major mishap that’s predominant is the fire accident caused due to leakage of LPG gas at home. There was ample number of cases investigated and published in the newspapers more often. The proposed system focuses on a system which precludes such mishaps that causes fatal burns and injuries to the lives in that particular vicinity. The system contains gas sensor, PIR sensor and temperature sensor which is used for monitoring and sensing the gas leakage in the kitchen or industry and reacts to it through the micro-controller which turns off the stove/valve by a DC motor that is interfaced with the knob. Also, for a preventive action, it activates the alarm and sends a display text in the other room through Li-Fi communication.

Perovskite light-emitting/detecting bifunctional fibres for wearable LiFi communication

Light fidelity (LiFi), which is emerging as a compelling technology paradigm shifting the common means of high-capacity wireless communication technologies, requires wearable and full-duplex compact design because of its great significance in smart wearables as well as the ‘Internet of Things’. However, the construction of the key component of wearable full-duplex LiFi, light-emitting/detecting bifunctional fibres, is still challenging because of the conflicting process between carrier separation and recombination, as well as the highly dynamic film-forming process. Here, we demonstrate light-emitting/detecting bifunctional fibres enabled by perovskite QDs with hybrid components. The hybrid perovskite inks endow fibres with super-smooth QD films. This, combined with the small exciton binding energy and high carrier mobility of perovskite QDs, enables successful integration of electroluminescence and photodetection into monofilaments. The bifunctional fibres possess the narrowest electroluminescence full width at half maximum of ~19 nm and, more importantly, the capability for simultaneously transmitting and receiving information. The successful fabrication of narrow emission full-duplex LiFi fibres paves the way for the fabrication and integration of low crosstalk interoperable smart wearables.

Method for calculating optical elements for Li-Fi communication devices of vehicles

Method for calculating optical elements for Li-Fi communication devices of vehicles