LiFi Networks Research Articles

Parametric evaluation of line-of-sight (LOS) channel in LiFi networks

Parametric evaluation of line-of-sight (LOS) channel in LiFi networks

Methods and Software Tools for Reliable Operation of Flying LiFi Networks in Destruction Conditions.

The analysis of utilising unmanned aerial vehicles (UAVs) to form flying networks in obstacle conditions and various algorithms for obstacle avoidance is conducted. A planning scheme for deploying a flying LiFi network based on UAVs in a production facility with obstacles is developed and described. Such networks are necessary to ensure reliable data transmission from sensors or other sources of information located in dangerous or hard-to-reach places to the crisis centre. Based on the planning scheme, the following stages are described: (1) laying the LiFi signal propagation route in conditions of interference, (2) placement of the UAV at the specified points of the laid route for the deployment of the LiFi network, and (3) ensuring the reliability of the deployed LiFi network. Strategies for deploying UAVs from a stationary depot to form a flying LiFi network in a room with obstacles are considered, namely the strategy of the first point for the route, the strategy of radial movement, and the strategy of the middle point for the route. Methods for ensuring the uninterrupted functioning of the flying LiFi network with the required level of reliability within a given time are developed and discussed. To implement the planning stages for deploying the UAV flying LiFi network in a production facility with obstacles, the "Simulation Way" and "Reliability Level" software tools are developed and described. Examples of utilising the proposed software tools are given.

Is LiFi Technology Ready for Manufacturing and Adoption? An End-user questionnaire-based study

Because of the exponential development of emerging technologies and the increase of devices that use the internet, the wireless fidelity (WiFi) spectrum has been saturated, therefore, the light fidelity (LiFi) has been under development for wireless communication including internet access. LiFi network systems can provide high speed data rates with high security. However, LiFi is still under development and research, and is not yet popular for end-users to be used in homes, companies, and other industries. Therefore, for the first time, this study investigates the adoption probability of LiFi technology by the end-users to anticipate the success rate when launching ready-to-use LiFi devices for end-users by the manufacturer companies. A well-designed questionnaire is used in this study for data collection. A total of 100 participants from around the world have been chosen to fill-up the questionnaire forms including three phases: basic information, preferences, and usage, and LiFi and Pricing. The findings of this study show a high and positive probability for adoption rate of LiFi technology. However, the pricing aspect has a critical impact on the acceptance of using LiFi systems by the end-users.

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.

Modulating LiFi for dual operation in the visible and infrared spectra

Light-Fidelity (LiFi) has emerged in the last few years as a promising technology for alleviating the stringent demand for wireless data services. Prior works have considered LiFi operating either in the visible light or infrared spectrum. Each spectrum band has its own advantages: visible light allows leveraging existing infrastructure for communication, while infrared is not affected by light dimming. In this work, we propose a modulation scheme that retains the benefits of both bands, introducing a simple, low-cost, yet efficient dimming solution for LiFi networks. We compare the performance of the proposed dimming scheme with both the digital and analog dimming techniques traditionally used in LiFi systems. Simulation results show that our dimming solution offers better communication and illumination performance than previous proposals, providing larger signal-to-noise ratio, spectral efficiency, and a full and fine-grained dimming range. Finally, we prototype our solution by designing an extended version of the OpenVLC 1.3 platform, and we experimentally show its robust communication performance under different dimming conditions. We make the implemented system publicly available to the research community.

Card-Flipping Decision-Making Technique for Handover Skipping and Access Point Assignment: A Novel Approach for Hybrid LiFi Networks

Card-Flipping Decision-Making Technique for Handover Skipping and Access Point Assignment: A Novel Approach for Hybrid LiFi Networks

Load Balancing in the Combined Technology of Li-fi and Wi-Fi based on Collaborative Game

Wireless networks have become increasingly important in today's digital age. The combination of VLC and RF technologies, such as local Wi-Fi and Li-Fi networks, has emerged as a significant technology in this field. This combination enhances the coverage of weak points and strengthens the strong points of local wireless networks, resulting in higher data rates and increased coverage. However, load balancing is a crucial issue that can enhance network efficiency, especially when there are multiple access points from both networks. The selection of the appropriate access point at any given time by different nodes can significantly impact network performance. This research proposes a game theory-based method for selecting an appropriate access point, which uses multiple stages of computation and policy changes to achieve a Nash equilibrium in the game and subsequently in the network. The results show that this method can improve the quality of service in the local network by over 6% compared to previous methods such as the fuzzy method and by over 20% compared to the higher signal power selection policy.

Li-Fi technology based long range free-space communication data transmit system evaluation

AbstractThe most flexible and reliable technological system is Wi-Fi, which is made possible by a wireless connection that transmits data using radio frequencies. Wi-Fi networks, however, encounter numerous issues related to power supply, availability, efficiency, and security as a result of the various access points. While relational waves describe the medical device, Wi-Fi radios produce radio waves that are very dangerous for patients. This document offers line-of-sight communication between the transmitter and receiver using LED technology. Li-Fi technology is a method that transmits audio data using LED light, which is faster and more efficient than Wi-Fi. Since it is practically ubiquitous, light can be used for communication as well. A cutting-edge technology called optical communication includes a subset called light fidelity. By sending out visible light, the Li-Fi device enables wireless intranet communication. This paper is an in-depth study and analysis of Light Fidelity (Li-Fi), a novel technology that transmits data at high speeds over a wide spectrum by using light as a medium of transmission. The research fields that are pertinent to Li-Fi networks are thoroughly analyzed and categorized in this paper: high speed data transmission, receiving, sharing, broadcasting through light in free space optical communication system by Li-Fi technology. In this paper, we followed some methods and developed a unique method to develop this study: VLC, OOK, a Lambertian discharge mechanism, LOS, NLOS, or a CMOS optical receiver. The proposed model tested transmits and receives audio, video, and other data, which is very high-rated and near the 2 GB/s range.

Li-Fi Technology Based Long Range Free-Space Optics Data Transmit System Evaluation

INTRODUCTION: The most flexible and reliable technological system is Wi-Fi, which is made possible by a wireless connection that transmits data using radio frequencies. Wi-Fi networks, however, encounter numerous issues related to power supply, availability, efficiency, and security as a result of the various access points. While relational waves describe the medical device, Wi-Fi radios produce radio waves that are very dangerous for patients. This document offers line-of-sight communication between the transmitter and receiver using LED technology. Li-Fi technology is a method that transmits audio data using LED light, which is faster and more efficient than Wi-Fi. Since it is practically ubiquitous, light can be used for communication as well. A cutting-edge technology called optical communication includes a subset called light fidelity. By sending out visible light, the Li-Fi device enables wireless intranet communication. This paper is an in-depth study and analysis of Light Fidelity (Li-Fi), a novel technology that transmits data at high speeds over a wide spectrum by using light as a medium of transmission. The research fields that are pertinent to Li-Fi networks are thoroughly analyzed and categorized in this paper.OBJECTIVES: High speed data transmission, receive, share, broadcast through light in free space optical communication system by Li-Fi technology.METHODS: We followed some methods and developed a unique method to develop this project. which is VLC, OOK, a Lambertian discharge mechanism, LOS, NLOS, or a CMOS optical receiver.RESULTS: Successfully, we transmitted and received audio, video, and other data, which is very high-rated and near the 2 GB/s range.CONCLUSION: Visible light communication may be a fast-evolving technique in the field of wireless technology. Li-Fi is a wireless data transfer system that is both fast and inexpensive. It can also be used in potentially hazardous situations, such as in nuclear power plants, without causing electromagnetic interference. We are considering adding more features to our project in the future to get better outcomes.

Highly Sensitive SPAD-Based Receiver for Dimming Control in LiFi Networks

Visible light communication (VLC) is an emerging mode of wireless communication that supports both illumination and communication. One essential function of VLC systems is the dimming control, which requires a sensitive receiver for low-light conditions. The use of an array of single-photon avalanche diodes (SPADs) is one promising approach to enhancing receivers’ sensitivity in a VLC system. However, because of the non-linear effects brought on by the SPAD dead time, an increase in the brightness of the light might degrade its performance. In this paper, an adaptive SPAD receiver is proposed for VLC systems to ensure reliable operation under various dimming levels. In the proposed receiver, a variable optical attenuator (VOA) is used to adaptively control the SPAD’s incident photon rate according to the instantaneous received optical power so that SPAD operates in its optimal conditions. The application of the proposed receiver in systems with various modulation schemes is investigated. When binary on–off keying (OOK) modulation is employed due to its good power efficiency, two dimming control methods of the IEEE 802.15.7 standard based on analogue and digital dimming are considered. We also investigate the application of the proposed receiver in the spectral efficient VLC systems with multi-carrier modulation schemes, i.e., direct current (DCO) and asymmetrically clipped optical (ACO) orthogonal frequency division multiplexing (OFDM). Through extensive numerical results, it is demonstrated that the suggested adaptive receiver outperforms the conventional PIN PD and SPAD array receivers in terms of bit error rate (BER) and achievable data rate.

Techno-economic study of very dense optical wireless access using visible or infrared light

Future wireless networks need to serve a high density of end-user devices with a high quality of service. The density of wireless access points and the infrastructure behind them lead to substantial cost. We study this cost impact for the particular case of optical wireless communication [also denoted as light fidelity (LiFi)] in a large manufacturing hall. We compare different LiFi network topologies using visible or infrared light. Considering aspects such as the fronthaul cabling layout, equipment investments, and installation and operational costs for energy and maintenance, different LiFi solutions are analyzed for greenfield and brownfield scenarios. The techno-economic analysis is performed in terms of total cost of ownership as well as the impact of each cost category to the final cost. Furthermore, the cost per delivered Mbps is compared to take into account the expected densification (more bits/s/m2) and satisfy the demand for future wireless traffic. Both delivered capacity and power consumption have been identified as the two most critical parameters.

LiFi-Based D2D Communication in Industrial IoT

This article analyzes the performance of light fidelity (LiFi)-based device-to-device (D2D) communication in industrial Internet-of-Things (IIoT). We present a comprehensive analysis of mobility management of D2D communication in industrial LiFi networks. Using the semiangle at half illuminance of the AP and D2D transmitting IIoT, a coverage model for the D2D communication range is derived. By adopting stochastic geometry, closed-form expressions for mode selection rate and residence time are derived as functions of the AP density, IIoT density, and velocity. The results have shown that high velocity and denser deployment cause a decrease in the average D2D residence time and an increase in the average D2D transition rate or vice versa. The proposed analytical models are then verified with Monte Carlo simulation results. The results provide system-level design insights.

Bi-group pre-handover authentication model solving signaling congestion of subway LiFi network

In the metro scenario, massive users will switch from the platform network to the subway network simultaneously. The resulting huge and burst authentication traffic could cause signaling congestion in the subway light fidelity (LiFi) network. In this paper, a bi-group pre-handover authentication model (BGPHA) is developed to solve this problem by analyzing the characteristics of LiFi networks and the mobility of metro users. Specifically, a bi-group authentication mechanism is created in the BGPHA based on the ultra-dense deployment characteristic of LiFi networks. Next, a re-authentication mechanism is created in the BGPHA based on the link vulnerability characteristic of LiFi networks. Besides, a quick rejoin mechanism is created in the BGPHA based on the random mobility of metro users. Finally, the effectiveness of BGPHA is demonstrated by numerical and simulation analysis. Numerical analysis indicates that BGPHA has a lower authentication overhead growth with the number of users compared to the conventional single-group authentication scheme. Simulation analysis demonstrates that BGPHA can significantly decrease the handover latency in the presence of light path blockages. Furthermore, the handover failure rate can be effectively reduced by up to 6 times with the BGPHA.

A Multicriteria Decision-Making Framework for Access Point Selection in Hybrid LiFi/WiFi Networks Using Integrated AHP-VIKOR Technique.

Since light fidelity (LiFi) and wireless fidelity (WiFi) do not interfere with one another, a LiFi/WiFi hybrid network may provide superior performance to existing wireless options. With many users and constant changes, a network can easily become overloaded, leading to slowdowns and fluctuations in data transfer speeds. Access point assignment (APA) is required with the increase of users, which can negatively impact the system performance and quality-of-service (QoS) due to mobility and line-of-sight (LOS) blockage. Many variables could influence the APA process; these variables are considered as criteria, such as the network capacity, the degree of blockage, the speed of the connected user, etc. Unlike conditional APA methods, recent studies have considered treating these variables as "evaluation criteria". Considering these criteria can offer better and more accurate results, eventually enhancing the APA process and QoS. However, the variety of these criteria, the conflict amongst them, their weights (importance), and priority have not been addressed so far. Moreover, treating the criteria equally might result in inaccurate outcomes. Therefore, to solve this issue, it is essential to investigate the impact of each criterion on the APA process. In this work, a multicriteria decision-making (MCDM) problem is formulated to determine a network-level selection for each user over a period of time The decision problem is modeled as a hierarchy that fragments a problem into a hierarchy of simple and small subproblems, and the selection of the AP network among various alternatives is a considered as an MCDM problem. Based on the previous works, we are not aware of any previous research attempts using MCDM methods in the LiFi research area for network selection. Therefore, this work proposes an access point assignment framework using an MCDM approach for users in a hybrid LiFi/WiFi network. The experiment was conducted based on four phases: Five criteria were identified and evaluated with eleven APs (alternatives). The outcome of this phase was used to build the decision matrix and an MCDM was developed and built based on user mobility and blockages with various scenarios using all the criteria; The analytic hierarchy process (AHP) was employed to identify the criterion of the subjective weights of each criterion and to determine the degree of importance supported by experts' judgement. Determining the weights in the AHP process considered various investigations, including the consistency ratio (CR) and the AHP consensus indicator, which is calculated using the rank-based maximum likelihood method (RGMM) and Shannon entropy techniques. The VIekriteri-Jumsko KOmpromisno Rangiranje (VIKOR) method is adopted in the selection of the optimal AP for the proper selection of whether a LiFi or WiFi AP must serve the users. The integrated AHP-VIKOR was effective for solving the APA and was the best solution based on using weighted criteria simultaneously. Moreover, the ranking outcomes of the developed integrated AHP-VIKOR approach were evaluated using sensitivity analysis. The result of this work takes the APA for hybrid LiFi networks to a new perspective.

Priority based flow control protocol for internet of things built on light fidelity

<span>Excessive usage of Internet by most of the applications that use internet of things (IoT) has resulted in need for high bandwidth network. Light fidelity (LiFi) is one such network having bandwidth in terms of GigaHertz, but LiFi has a limited propagation range hence it can be deployed only in the local area. When IoT nodes are connected using LiFi network in the local area they start pushing large data to the cloud there by arising need for flow control. Some of the IoT applications such as patient monitoring systems and nuclear systems, generate critical data. The protocol for flow control in this case should be based on priority of data since critical data with high priority have to be transmitted first. We develop a flow control protocol named priority based flow control protocol (PFCP) by providing priority to flows that carry critical data especially in IoT system that use LiFi network. We evaluate performance of different transmission control protocol (TCP) variants and modify TCP variant that yields maximum goodput according to the priority based protocol developed and demonstrate that flows that carry critical data are given priority compared to non-prioritized flows</span>

A dynamic handover scheme based on bidirectional VLC channel in multi-user attocell networks

Light fidelity (LiFi) would be a potential optical wireless communications technology for future mixed-spectrum 5G/6G indoor attocell network, which uses light-emitting diodes based as an optical antenna and offers Gbits capacity. For this scenario, a dynamic handover scheme based on bidirectional visible light communications (VLC) channel is proposed, which uses the uplink light sources to characterize terminal’s movement status for the mobility and make the handover decision in contrast to the unidirectional links. The uplink reference signal received power and the movement state are examined, and the created algorithm is executed in the bidirectional VLC test bed. The experimental results show that the proposed method will reduce the terminal’s handover rate by up to 45% and increase the optical network throughput by up to 26% at the experimental data rate compared with the skipping handover scheme for indoor LiFi network.

Founding AP's IVM and related IHM for subway LiFi network

In this paper, the information value model (IVM) of an access point (AP) and the related intelligent handover model (IHM) are firstly founded in the subway light-fidelity (LiFi) network. At first, based on statistical methods, the IVM is created by analyzing the behavioral characteristics of subway passengers. By the IVM, the probability of user access to each AP can be successfully predicted. Next, based on this probability, the IHM is created by deeply analyzing the alternating blockage problem of handholds. By the IHM, the system can self-adapt to the hysteresis state. This not only effectively avoids ping-pong handovers, but also reduces outage probability. Finally, by simulation, the effectiveness of the above IVM and IHM has been demonstrated. The simulation results indicate that the accuracy of predicting user target AP can be up to 92% by the IVM. Specially, compared with using the standard handover model, the throughput of the network not only increases 11.5%, but also the outage probability of the network decreases 23.6% by using the IHM.

Impact of a Randomly Placed Terminal on LiFi Performance

The ambitious goal of light-fidelity (LiFi) technology to provide seamless user mobility in indoor environments requires strong link connections to confront any stochasticity that possibly comes out. In this context, a robust LiFi network should effectively address the spatial random terminal locations inside its coverage volume. In contrast with the previously published works dealing mainly with randomness in two dimensions, the present study aims to provide a more realistic framework by treating the problem in the three-dimensional space. In view of the foregoing, a LiFi configuration is adopted where a terminal lies at a random position inside its truncated conic coverage volume at a distance from the transmitter. Some key statistics for a distance-related metric and the channel gain, including the probability density function, are derived in the first place. The investigation is then headed on the performance analysis of the LiFi link by providing closed-form expressions of the outage probability and the average bit error rate for on-off keying assuming indirect modulation/direct detection at the receiver. A multiuser scenario with several users placed inside the coverage volume is examined as well. A series of numerical results is also depicted to provide valuable insights into how the random terminal placement affects the link performance.

Perylene-Based Chromophore as a Versatile Dye for Light Amplification.

One of the challenges for modern optoelectronics is to find versatile, easily adaptable components for novel laser-based technologies. A very attractive perylene-derivative chromophore in different organic matrices for high-performance light amplification is discussed and outlined. Our approach demonstrates the outstandingly compatible laser dye and a viable strategy to provide an effective optical gain for stimulated emission enhancement. Through structural control, we produce simple optical devices embedded in organic matrices, such as poly(methyl methacrylate), nematic liquid crystalline (NLC) mixture, and a hybrid emulsion system (poly(vinyl alcohol) PVA + NLC mesophase). Importantly, we investigate and compare the spectroscopy of differently constructed organic systems in terms of stimulated-emission thresholds and light amplification process efficiency. Moreover, we report the effects of tunability for LC cells by an applied external electric field stimulus. Future directions of laser systems are outlined with an emphasis on the role of the perylene derivative. The studies meet current challenges in the field of modern organic technologies dedicated to various optoelectronic systems, including touch screens, displays, and Li-Fi networks.

Securing the light escaping in a Li-Fi network environment

Nowadays, everyone knows Wi-Fi. The technology that ensures connection of computer equipment. It is now positioned as the easiest way to interconnect multiple end users because It allows user mobility in workspaces, avoids cable clutter within the network coverage, such as offices, homes and so on. Despite these advantages, several scientific studies have shown that this technology can raise security and safety issues and is dangerous to human health, and therefore not suitable for hospital networks. In an attempt to overcome these difficulties, Li-Fi technology based on visible light is beginning to interest researchers. This technology is considered more secure than Wi-Fi because the light can be contained in a physical space and waves can’t pass through walls and other objects. Unfortunately, when the physical environment contains spaces that can escape light to the outdoors, this can be a security risk for Li-Fi because it uses light sources to transmit data. That why, in this paper, the main differences between Wi-Fi and Li-Fi technologies are explained, and a Li-Fi architecture provided with an authentification captive portal and a data transfer security mechanism between end users based on the AES algorithm is proposed. The developed prototype and the architecture proposed guarantee the security of the Li-Fi network even if the physical environment is provided with multiple light escape spaces.