Scheduling for indoor visible light communication based on graph theory.

Visible Light Communications (VLC) technology is restricted by the transmission coverage, which is short by nature. This is imposed by the lighting range which barely reaches a couple of hundred meters. The number of applications of VLC technology is therefore limited by this specific characteristic of the light propagation. As a result, VLC cannot be used in long and medium distance communication systems. The technology is suitable for exploitation in optical wireless personal area networks (OWPAN) in which the mobile terminal (MT) and the VLC access point (VLC AP) are placed in the same room. It is then essential that the access point is fed by a backhaul network. In this paper, we propose an access network in which the backhaul or backbone network exploits fibre optic (FO) technology to feed the VLC access point with data to be retransmitted. The channel is analyzed for a few parameters of the entire system including the FO attenuation factor, α, the transmission range, L, and the indoor VLC wall, ceiling and floor reflection coefficient, ρ.

Visible light communication technology is a wireless optical communication technology based on LED lighting. [1] Making use of the high speed response characteristic of LED, visible light communication technology can realize the dual functions of lighting and communication. As a new way of data access and a supplement to radio frequency communication, visible light communication has been widely concerned. This paper is based on the development of application-oriented visible light communication system based on intelligent terminal, in order to accelerate the practical process of visible light communication. By changing the traditional visible light receiving scheme and using smart phone as the receiving device of the visible light system, a visible light communication system based on intelligent terminal is built [2]. Through the research on the existing receiving algorithm, a new receiving algorithm is proposed to improve the adaptability and BER performance of the system.

This paper analyzes the performance of a dual-hop hybrid radio frequency - visible light communications (VLCs) system. VLC exploits high frequencies for signal propagation for short-range and is highly susceptible to blockages. Hence, in this work, the sensitivity of the VLC toward the blockages is explored. This study examines outdoor-indoor communication for an urban scenario featuring an office environment. The VLC system is designed by considering multiple VLC access points serving the end users in the presence of human blockages. Selection combining is employed to select the access point which offers the maximum instantaneous signal-to-noise ratio at the user. To capture the outdoor scenario, path loss modeling is conducted to account for signal attenuation from outdoor to indoor spaces. The outdoor scenario is modeled using Nakagami-m fading channels while VLC is employed for the indoor scenario. System performance is assessed in closed-form expression for outage probability and the symbol error rate for binary phase shift keying and quadrature amplitude modulation. A deep learning-based approach detects the symbols by tracking dynamic changes in the channel. Simulation results corroborate the correctness of derived analytical expressions and reveal that blockages significantly impact both single and multiple LED based communication channels.

Li-Fi stands for Light-Fidelity. This technology is very new and was proposed by the German physicist Harald Haas in 2011. Light based communication system is the backbone of the future of the communication system. Li-Fi is a wireless technology that uses light emitting diodes (LEDs) for transmission of data. The development of the wireless communication leads to advance research in LiFi technology. The term Li-Fi states to visible light communication (VLC) technology that uses as medium to deliver high-speed communication in a fashion similar to Wi-Fi. Li-Fi comprises a wide range of frequencies and wavelengths, from the Infrared through visible and down to the Ultraviolet spectrum. The immense use of Li-Fi may solve some bottleneck of data transmission in Wi-Fi technology. With the innovation in technology and the number of users, the existing radio-wave spectrum fails to accommodate this need. To resolve the issues of scalability, availability and security, we have come up with the concept of transmitting data wirelessly through light using visible light communication (VLC) technology. This paper objective is to study and describe the LiFi technology. The improvement of the wireless communication leads to advance research in LiFi technology through Visible Light Communications (VLC) Technology.

Visible light communication (VLC) has emerged as a viable complement to traditional radio frequency (RF) based systems and as an enabler for high data rate communications for beyond-5G (B5G) indoor communication systems. In particular, the emergence of new B5G-based applications with quality of service (QoS) requirements and massive connectivity has recently led to research on the required service-levels and the development of improved physical (PHY) layer methods. As part of recent VLC standards development activities, the IEEE has formed the 802.11bb “Light Communications (LC) for Wireless Local Area Networking” standardization group. This paper investigates the network requirements of 5G indoor services such as virtual reality (VR) and high-definition (HD) video for residential environments using VLC. In this paper, we consider such typical VLC scenarios with additional impairments such as light-emitting diode (LED) nonlinearity and imperfect channel feedback, and propose hyperparameter-free mitigation techniques using Reproducing Kernel Hilbert Space (RKHS) methods. In this context, we also propose using a direct current biased optical orthogonal frequency division multiplexing (DCO-OFDM)-based adaptive VLC transmission method that uses precomputed bit error rate (BER) expressions for these RKHS-based detection methods and performs adaptive BER-based modulation-order switching. Simulations of channel impulse responses (CIRs) show that the adaptive transmission method provides significantly improved error rate performance, which makes it promising for high data rate VLC-based 5G indoor services.

This article reviews the visible light communications (VLC), a technology in which the visible spectrum is modulated to transmit data. It presents the VLC communication system: the transmitter, the channel, and the receiver. The single and multichannel transceivers are presented. The channel for a system that uses a single light‐emitting diodes (LED) and the matrix representing the multicolor channel are discussed. Various modulation schemes, basic techniques used to implement a VLC system, and different causes of dimming are discussed. In addition, standardization of the VLC technology, applications, as well as challenges for VLC practical implementation and commercialization are reviewed.

Facing the current shortage of radio frequency spectrum resources, visible light communications (VLC) technology has been proposed to be a candidate technology in the sixth generation (6G), especially in the application of Intelligent Transportation Systems (ITS). And the propagation characteristics of VLC channel are critical for VLC system design and optimization. Furthermore, the impact of weather conditions on VLC channel cannot be ignored considering the vehicular VLC in ITS. In this paper, we experimentally investigate the impact of different weather types including fog and relative humidity (RH) on VLC in a laboratory atmospheric chamber. To simulate adverse weather conditions, we change the levels of fog density and water vapor introduced into the chamber, respectively. Then we measure the power attenuation and the bit error rate (BER) performance of VLC system under fog and RH conditions. We find that the VLC system will exhibit worse BER performance in the fog impaired channel than RH conditions. Besides, the results show that the bit errors will not happen until the attenuation reaches the threshold, i.e. attenuated by about 60% for both fog and RH conditions in our experiments. After that, the BER will deteriorate badly even up to 20%.

Indoor visible light positioning becomes attractive due to the increasing demands of location-based services. In this paper, we presented a model of an indoor positioning system based on visible light communication technology firstly. The system uses white light emitting diodes (LED) as light sources, so it has the dual role of communication and lighting. Then, the transmitter and receiver of visible light communication in the system have been designed and realized. Next, a coding protocol was designed and implemented, which can be used to transmit ID of each light source. Finally, the error performance in experiments of the proposed system is analyzed and several suggestions on future research of indoor positioning based on visible light communication were given.

Nowadays, with the incursion of solid state lighting technology in our daily life, visible light communication (VLC) systems are becoming more important. This fact has generated a lot of attention on VLC to provide solutions on multiple applications where this technology can be exploited. At the same time, the growing of automation processes has created the necessity of knowing the localization of different objects and devices. Indoor localization based on radio frequency signals is one of the most used techniques (Wi‐Fi, Bluetooth, UWB, RFID, etc); however, VLC is a new and interesting method, which is gaining enormous research attention. Moreover, there are environments where the use of RF technologies is restricted or even prohibited. In such cases, VLC technology becomes an interesting alternative to solve this problem. In this paper, we design and implement a novel VLC‐based indoor localization system that combines the application of a VLC scheme for downlink and an ultrasonic communication for the uplink. Practical localization experiments are carried out in an actual office room environment, and results show a localization accuracy of 4 cm on average for direct links and 10 cm for indirect links.

The growing energy consumption of communication systems raises economical and environmental concerns. Indoor visible light communication (VLC) systems are energy friendly as they exploit the illumination power of LED luminaries for data transmission. However, the VLC systems suffer from service disruptions due to the limited coverage of light. To alleviate this problem, hybrid RF#x002F;VLC architecture has been recently proposed for indoor networks where the RF networks can be exploited to resolve the limited VLC coverage. In this paper, we consider a network composed of multiple VLC access points and an RF access points. We develop resource allocation algorithms to maximize the system's power efficiency defined as the total system throughput per unit power. Simulations show that deploying VLC access points improves the power efficiency of the system and increases the minimum guaranteed rate per user. Simulations also show that higher power efficiency can be obtained using the same number of operating VLC access points by redistributing them more uniformly across the room.

Emerging white-light LEDs allow the combination of illumination and optical wireless communication in one optical source. Visible light communication (VLC) uses solid-state LEDs to broadcast information and is an attractive technology for indoor positioning system. In this paper, we propose a higher accuracy indoor positioning algorithm using a stereo image sensor and white-light LEDs by the visible light communication. Indoor white-light LEDs are located at the ceiling of a room and broadcast its position information by VLC technology. Mobile receiver with stereo image sensor receives LED position information by VLC and estimates its position and angle information. Simulation results are given to show the efficiency of proposed indoor positioning algorithm.

This paper presents the time hopping (TH) visible light communication (VLC) system for an electromagnetic wave free indoor healthcare. VLC technology has emerged as an alternative wireless communication due to various advantages such as ubiquity, low energy consumption, no radio frequency (RF) radiation, and security against undesired network access. Significant bio-medical signal including the electrocardiography (ECG) can be transferred with VLC even in places where RF is forbidden. This potential advantage of VLC could save more emergency patients. The time hopping scheme is adopted to transmit multiple medical data with keeping a simple system design. Multiple data streams go through an optical detector including a photodiode and multiple data are separated by TH demodulator at the receiver. Each separated signal is then monitored to serve the necessary medical care for the concerned patient.

Intelligent Transportation Systems (ITSs) are being proposed, examined, and applied to enhance road safety and traffic efficiency. However, the automotive industry has stringent criteria for safety applications that demand connections that are dependable and have low latency, and high data rates. In this paper, it is widely agreed that both Visible Light Communication (VLC) and Free Space Optics (FSO) represent promising solutions, because of their complementary advantages compared to Radio Frequency (RF). VLC technology is chosen in ITS overall other optical wireless systems primarily due to its low cost and lack of licensing or new infrastructure requirements. Hence, a comparative study is applied between standalone VLC system, and a hybrid FSO/VLC system in term of Bit Error Rate (BER), coverage distance, and Signal to Noise Ratio (SNR). The VLC/FSO system provides a reliable communication link over a long distance (900 m) compared to VLC standalone system with 10−6 BER and acceptable SNR of ∼\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sim$$\\end{document} 25 dB.

The radio frequency spectrum has become very congested and scarce. A response to this dilemma is the implementation of visible light communications (VLC) technology, which is enabled by the dramatic development of light emitting diodes (LEDs) and laser diodes (LDs). VLC has become the most popular emerging telecommunication technology. This is due to the interesting advantages that it provides, which include an unlicensed and large bandwidth, a high throughput capability and a low implementation cost. VLC needs a pivot network in medium and long distance transmissions. The amplify‐and‐forward scenario between the backbone network and VLC is cost‐effective owing to its simplicity when compared to the decode‐and‐forward scenario. MPSK‐CSK is a typical example of cascaded systems in AF scenario with VLC where the backbone channel utilises PSK to convey the message. In this paper, we investigate a forward error correction scheme for cascaded MPSK‐CSK systems. A convolutional encoder is added to the MPSK‐CSK scheme to construct the hybrid trellis coded modulation scheme. Selected 8HTCM systems using set partitioning are investigated and results for a Gaussian channel are presented. Numerical results reveal that 8HTCM achieves up to 2.129 dB of asymptotic coding gain when compared to the corresponding un‐coded MPSK‐CSK system.

Visible-light communication (VLC) has emerged as a promising technology to provide the very high-throughput wireless communications demanded by beyond-fifth-generation (B5G) applications. However, few works are found in the literature regarding the integration of VLC systems with other wireless communications technologies and with access networks. In this context, and as a proof of concept, we implement and experimentally evaluate a hybrid network architecture based on VLC, radio-over-fiber (RoF), free space optics (FSO), fiber-wireless (FiWi), and millimeter-waves (mm-waves) for B5G applications. Such optical networks make use of fiber-optic links based on RoF technology as backhauls, whereas their fronthauls might be either by FSO or RoF. Finally, a triple-wireless-access network is ensured by VLC, FiWi, and mm-wave links. The latter use a real 5G new radio (5G NR) signal. The system performance is evaluated in terms of a root mean square error vector magnitude (EVMRMS) parameter in accordance with the 3rd-Generation Partnership Project (3GPP) requirements. The experimental results demonstrate a total maximal theoretical throughput of approximately 1.66 Gbps, aligning with the digital performance requirements set by 3GPP.