Use Of Visible Light Communication Research Articles

Vehicular Visible Light Communication With Low Beam Transmitters in the Presence of Vertical Oscillation

The availability of light-emitting diodes (LEDs) in vehicle exteriors makes possible the use of visible light communication (VLC) as a vehicle-to-vehicle (V2V) wireless connectivity solution. Although high beam headlights offer higher illumination levels and further communication distances compared to low beam headlights, regulations restrict high beam utilization in many driving cases. These restrictions make low beam headlights a more suitable candidate for vehicular VLC systems. In this paper, we consider two heavy vehicles (e.g., trucks) on a road following each other. Low beam headlights of the follower truck act as wireless transmitters and the lead truck is equipped with a photodetector at its back. We first propose an accurate path loss model based on experimental measurements. The proposed model takes into account the presence of lateral shift between the trucks as well as the fact that headlamps and photodetector can be placed at different heights. Furthermore, we model the truck vertical oscillation experimentally at different speeds. Utilizing these models, we derive a bit error rate (BER) expression for VLC-based truck-to-truck communication system and investigate the effect of several system and channel parameters on the performance. In an attempt to mitigate the degrading effects of the vertical oscillation, we further investigate the proper selection of photodetector location in order to minimize the error rate performance.

Application of Optical Communication for an Enhanced Health and Safety System in Underground Mine.

The continuous monitoring systems developed for health and safety provisions in underground mines have always been a deep concern in mining activity, since this is one of the most dangerous work activities in the world. All mining activities must follow strict regulations that pose an increased responsibility for the design and implementation of novel technologies aiming to enhance both the workers' and equipment's safety in underground mines. Coal mines are some of the most dangerous, with high risk of explosion due to pit gas; therefore, we propose the use of visible light communication for local wireless transmission and optical fiber for remote-cabled transmission. We address, in this article, a complete system comprising real-time personnel tracking and environmental methane measurement, as well as the transmission of data, with a detailed explanation of the complete system and technical description with practical solutions applicable for industrial use.

Vehicular VLC System With Selection Combining

The availability of LED-based headlights and taillights makes possible the use of visible light communication (VLC) as a wireless access technology for vehicle-to-vehicle (V2V) communications. A critical concern to establish a reliable VLC link between two moving vehicles is the number of photodetectors and their locations on the destination vehicle. In this paper, we experimentally investigate the usage of dual photodetectors for a vehicular VLC system with selection combining to enhance signal reception in mobile conditions. We measure the electrical receive signal-to-noise ratio (SNR) for each individual photodetector as well as at the output of selection combiner in two different tracks involving straight and curved roads. Through data fitting to experimental data, we obtain a probability density function (PDF) to describe the instantaneous SNR. Based on the PDF, we derive a closed-form expression for the average bit error rate (BER) in the form of a finite summation and compare it with the measurements.

Analysis of Visible Light Communication using Integrated Avalanche Photodiode

The problem with Radio Frequency (RF) communication is that it has intrusion and high remission. Moreover, RF communication requires distinct configurations for transference and reception. To overcome these problems, Visible Light Communication (VLC) is recommended, as it has a high tolerance for bandwidth and interference. The usage of LEDs instead of fluorescent lamps uplifts the use of VLC. Visible light communication is a fast-evolving LED-based illumination and data transfer method. The performance of visible light communication over Mach-Zehnder Modulation has been investigated in this paper using the Opti-system simulation tool. The opti-system simulation programme predicts the quality factor and Bit Error Rate (BER) values of various link distances. The proposed system can handle 5 Gbps data rate over a 50-meter link distance with a Quality Factor of 15.71 and no external noise. The projected VLC system performance is further tested using a simulation tool in the case of external noise effects.

Smart vehicle lighting system based on a-SiCH technology

In this paper the use of Visible Light Communication (VLC) in Vehicle Communication Systems is analyzed. The system aims to ensure communication between LED based emitters and SiC based receivers located at the vehicles. The proposed smart lighting system combines the functions of lighting, positioning, and communications. The SiC receivers is used as a encoder/decoder device. This photosensitive element features active filter properties, it multiplexes the modulated polychromatic signal coming from the LEDs in an electrical signal, performs multiplexing/demultiplexing techniques and decode the received information. A traffic scenario is established and two connected vehicular communications simulated. Infrastructure-to-Vehicle (I2V) follow by Vehicle-to-Vehicle (V2V) communications are analyzed. In the V2V communication, the emitter is based on the front headlights of the vehicle, while for the study of the I2V communication system, the emitter was built on the streetlights. The VLC receiver acts as a Wavelength Division Multiplexer (WDM) and increases the signal conditioning capability to decode the transmitted information. Each receiver is a two terminal p-i'(a-SiC:H)-n/p-i(a-Si:H)-n heterostructure located on both the tails and on the top roof of vehicles. The spectral sensitivity of the receiver and its optical gain are analyzed. For message transmission, the individual chips of the white trichromatic RGB LEDs are modulated acting, for data transfer, as individual VLC channels. A violet LED is used for error control and to identify the ID position of the transmitter. Free space is the medium of transmission. An on-off modulation scheme (OOK) is used to transmit data. An algorithm for decoding information is established. The connected I2V2V system was tested. The experimental results show that using white modulated LEDs for lighting and data transmission and a SiC WDM device to decode the information is possible to build a VLC vehicular system that ensures de communication between the outside infrastructures and the cars. Copyright © 2018 VBRI Press.

Analysis and Experimental Investigation of the Light Dimming Effect on Automotive Visible Light Communications Performances.

The use of Visible Light Communications (VLC) in vehicular applications has become a major research area due to its simplicity, high performance to cost ratio, and great deployment potential. In this context, this article provides one of the very few analyses and experimental evaluations concerning the integration of a light dimming function in vehicular VLC systems. For this purpose, a vehicle-to-vehicle VLC prototype has been implemented and used to evaluate the systems’ communication performances in light dimming conditions, while decreasing the duty cycle from 40% to 1%, and increasing the communication range from 1 to 40–50 m. The experimental results showed that in normal lighting conditions, the VLC technology can easily support low duty cycle light dimming for ranges up to 40 m, while maintaining a 10−6 BER. Nevertheless, in strong optical noise conditions, when the system reaches its SNR limit, the communication range can decrease by half, whereas the BER can increase by 2–4 orders of magnitude. This article provides consistent evidence concerning the high potential of the VLC technology to support inter-vehicle communication links, even in light dimming conditions.

Evaluation of Misalignment Effect in Vehicle-to-Vehicle Visible Light Communications: Experimental Demonstration of a 75 Meters Link.

The use of visible light communications technology in communication-based vehicle applications is gaining more and more interest as the research community is constantly overcoming challenge after challenge. In this context, this article addresses the issues associated with the use of Visible Light Communications (VLC) technology in Vehicle-to-Vehicle (V2V) communications, while focusing on two crucial issues. On the one hand, it aims to investigate the achievable communication distance in V2V applications while addressing the least favorable case, namely the one when a standard vehicle rear lighting system is used as a VLC emitter. On the other hand, this article investigates another highly unfavorable use case scenario, i.e., the case when two vehicles are located on adjacent lanes, rather than on the same lane. In order to evaluate the compatibility of the VLC technology with the usage in inter-vehicle communication, a VLC prototype is intensively evaluated in outdoor conditions. The experimental results show a record V2V VLC distance of 75 m, while providing a Bit Error Ratio (BER) of 10−7–10−6. The results also show that the VLC technology is able to provide V2V connectivity even in a situation where the vehicles are located on adjacent lanes, without a major impact on the link performances. Nevertheless, this situation generates an initial no-coverage zone, which is determined by the VLC receiver reception angle, whereas in some cases, vehicle misalignment can generate a BER increase that can go up to two orders of magnitude.

Phosphor-free microLEDs with ultrafast and broadband features for visible light communications

Modulation bandwidth and the emission region are essential features for the widespread use of visible light communications (VLC). This paper addresses the contradictory requirements to achieve broadband and proposes ultrafast, asymmetric pyramids grown on adjacent deep concave holes via lateral overgrowth. Multicolor emission with an emission region between 420 nm and 600 nm is obtained by controlling the growth rate at different positions on the same face, which also can provide multiple subcarrier frequency points for the employment of wavelength division multiplexing technology. The spontaneous emission rate distinction is narrowed by lowering the number of the crystal plane, ensuring a high modulation bandwidth over broadband. More importantly, the residual stress and dislocation density were minimized by employing a patterned substrate, and lateral overgrowth resulted in a further enhancement of the recombination rate. Finally, the total modulation bandwidth of multiple subcarriers of the asymmetric pyramids is beyond GHz. These ultrafast, multicolor microLEDs are viable for application in VLC systems and may also enable applications for intelligent lighting and display.

Implementation of Vehicular-Visible Light Communication for motorcycle platooning

In this research, we explain the use of visible light communication technology for communication systems between motorbikes, where so far motorcycle lights have only been used for lighting or speed markers. But now, with visible light communication we can use it as a medium to communicate between vehicles, especially motorbikes. Visible light communication (VLC) is a communication system using visible light as an information carrier. VLC has many advantages including in terms of safety, speed, and ease of application to the user to send various types of information including digital data such as text and images. The VLC transmission section will use the LED motorcycle headlamps to send information to the receiver i.e. Light-to-Voltage Sensors are mounted on the back of a motorcycle when several motorbikes are in convoy or platooning. This study describes the use of VLC Vehicle-to-vehicle technology so that motorbikes can communicate with each other so that the motorcycle itself can adjust the distance with other motorbikes in front of him without being under or semi-controlled by the rider. From the results of measurements with the selected transmitter and receiver system, communication between motorbikes can be done up to 130 cm during the day and 180 cm at night. The potential of this technology is that it can truly support communication systems between vehicles such as self-driving motorcycles in the future.

Traffic Management with Deployment of Li-Fi Technology

Light Fidelity or commonly known as Li-fi, is an emerging technology that works on the principle of using light as a medium for transferring signals. It is bidirectional and is fully networked wireless communication that focuses on the use of light from light-emitting diodes (LEDs). The system is affluent and can provide connectivity within a larger area with more security, higher data rates and high-speed as compared to Wi-Fi. Apart from that, it relies on the use of visible light communication or infra-red and near-ultraviolet spectrum majorly working on the idea of switching bulbs on and off within nanoseconds. The paper consists of vivid insights about the use of Li-fi as a solution to the excessive traffic congestion in roadways. The paper is further divided into prominent sections that deal in providing an accurate idea about the working and implication of Li-fi technology in the current scenario. Moreover, the paper also proposes various technical standards and modulation that are and will be followed by Li-fi technologies, thereby focusing on its future implication. Apart from that, the main aim of designing the system is to limit traffic congestion and thus, reduce the increasing number of road accident in the present times.

Visible Light Communications for Industrial Applications—Challenges and Potentials

Visible Light Communication (VLC) is a short-range optical wireless communication technology that has been gaining attention due to its potential to offload heavy data traffic from the congested radio wireless spectrum. At the same time, wireless communications are becoming crucial to smart manufacturing within the scope of Industry 4.0. Industry 4.0 is a developing trend of high-speed data exchange in automation for manufacturing technologies and is referred to as the fourth industrial revolution. This trend requires fast, reliable, low-latency, and cost-effective data transmissions with fast synchronizations to ensure smooth operations for various processes. VLC is capable of providing reliable, low-latency, and secure connections that do not penetrate walls and is immune to electromagnetic interference. As such, this paper aims to show the potential of VLC for industrial wireless applications by examining the latest research work in VLC systems. This work also highlights and classifies challenges that might arise with the applicability of VLC and visible light positioning (VLP) systems in these settings. Given the previous work performed in these areas, and the major ongoing experimental projects looking into the use of VLC systems for industrial applications, the use of VLC and VLP systems for industrial applications shows promising potential.

Comparison of nonlinear equalizers for high-speed visible light communication utilizing silicon substrate phosphorescent white LED.

Compared with multicolor-chip integrated white LEDs, phosphor-based white LEDs are more attractive for daily illumination due to lower cost and complexity, and thus they are preferable for future commercial use of visible light communication (VLC) systems. However, the application of phosphorescent white LEDs has a lower data rate than multicolor-chip integrated LEDs because of severe nonlinear impairments and limited bandwidth caused by the slow-responding phosphor. In this paper, for the first time we propose to employ phosphorescent white LEDs based on silicon substrate with adaptive bit-loading discrete multitone (DMT) modulation and a memoryless polynomial based nonlinear equalizer to achieve a high-speed VLC system. We also present a comprehensive comparison among nonlinear equalizers based on the Volterra series model, memory polynomial model, memoryless polynomial model and deep neural network (DNN) with experimental results utilizing a silicon substrate phosphorescent white LED, and provide detailed suggestions on how to choose the most suitable nonlinear mitigation scheme considering different practical conditions and the tradeoff between complexity and performance. Beyond 3.00 Gb/s DMT VLC transmission over 1-m indoor free space is successfully demonstrated with bit error rate (BER) under the 7% forward error correction (FEC) limit of 3.8×10-3. As far as we know, this is the highest data rate ever reported for VLC systems based on a single high-power phosphorescent white LED.

ВИКОРИСТАННЯ ПРОГРАМНО-КОНФІГУРОВАНОГО РАДІО ДЛЯ ДОСЛІДЖЕННЯ ПЕРЕДАЧІ СИГНАЛІВ У ВИДИМОМУ СВІТЛІ

In the work, proposals have been developed for building a stand using GNU Radio for researching data transmission technology using visible light technology. Visible light communication (VLC) can be used to build high-bandwidth, high-speed wireless access networks. The main advantage of visible light communication is that RF signals are not obstructed. This makes it possible to use visible light communication in hospitals, on space stations, and so it makes it possible to communicate underwater. Security, simple implementation procedures and range characteristics, license-free, also increase the use of visible light communication for a variety of applications. The aim of this work is to provide guidance on the design and implementation of a visible light communication test bench using software-defined radio. The article describes the architecture of VLC, presents the possibilities of using Software Defined Radio as a starting point for developing commercial VLC applications SDR technology provides a framework that can help drive programs to market, generate interest from industry players, and shorten the time to market for future compliant products. The key issues in the implementation of the VLC system is to ensure the ability to transmit data for an LED luminaire with minimal changes in its lighting characteristics and production costs. Thus, this implementation can be improved by narrowing the gap between the industry and the research community. A prototype for visible light transmission was designed using software-defined radios to communicate between analog devices and the computer on which the signal is processed. Using this concept provides the system with sufficient flexibility and modularity to incorporate new features into a prototype without requiring a long development time. Conducted testing of this platform, during which it was possible to transfer a text file. It is concluded that this implementation of the visible light transmission stand can serve as a starting point for the development of low to medium bit rate commercial VLC applications.

Error compensation in indoor positioning systems based on software defined visible light communication

Visible Light Communication (VLC) paradigm allows the reusing of existing illuminating infrastructures in order to provide data communication. VLC can be considered a promising technology also for positioning in indoor environments, due to its potentially high accuracy and low costs. However, the main obstacle to the use of VLC for localization purposes is the high level of environmental noises, mainly due to sunlight. A novel approach, for easily measuring environmental noises and compensating their effects on localization results performed by an Indoor Positioning System (IPS) based on VLC, is proposed in this work. Frequency Division Multiplexing (FDM) is adopted to divide the total bandwidth into a series of non-overlapping frequency sub-bands corresponding to each signal, while an estimation of Signal to Noise Ratio (SNR), obtained through real time Power Spectral Density measurements in the proper frequency ranges, is exploited to compensate the error in positioning due to sunlight and other wide-band external optical disturbing signals. The proposed approach has been validated through experimental tests, carried out using a simple deployment of low power lamps, low cost hardware and a software defined approach. In the region under test, receiver position has been experimentally detected with higher accuracy in comparison to classical FDM approach, confirming the correctness and effectiveness of our proposed technique. In order to further validate the proposed approach, an additive measurement campaign has been successfully carried out considering a scenario characterized by very low SNR levels.

Cooperative vehicular communication systems based on visible light communication

The use of visible light communication (VLC) in vehicular communication systems for vehicle safety applications is proposed. The system aims to ensure the communication between a LED-based VLC emitter and an on-vehicle VLC receiver. A traffic scenario is established. Vehicle-to-vehicle (V2V) and infrastructure-to-vehicle (I2V) communications are analyzed. For the V2V communication study, the emitter was developed based on the vehicle headlights, whereas for the study of I2V communication system, the emitter was built based on streetlights. The VLC receiver is based on amorphous SiC technology and enhances the conditioning of the signal enabling to decode the transmitted information. Receivers are located at the rooftop of the vehicle, for I2V communications, and at the tails for V2V reception. Clusters of emitters, in a square topology, are used in the I2V transmission. The information and the ID code of each emitter in the network are sent simultaneously by modulating the individual chips of the trichromatic white LED. Free space is the transmission medium. An on–off code is used to transmit data. An algorithm to decode the information at the receivers is set. The proposed system was tested. The experimental results confirmed that the proposed cooperative VLC architecture is suitable for the intended applications.

Visible Light Channel Modeling for Gas Pipelines

In this paper, we explore the use of visible light communication as a means of wireless monitoring in gas pipelines. In an effort to shed light on the communication limits in the presence of gas, we create a three-dimensional simulation platform where the pipeline size/shape, the reflection characteristics of the interior coating, gas specifications (i.e., temperature, density, refractive index, transmittance, etc.) and the specifications of the light sources and detectors (i.e., field of view, lighting pattern, etc.) are precisely defined. Based on ray tracing, we obtain channel impulse responses within the gas pipeline considering the deployment of different colored LEDs with various viewing angles. We further investigate the maximum achievable link range to ensure a given bit error rate.

Optical communication applications based on white LEDs

In this paper is proposed an indoor navigation system based on the use of Visible Light Communication (VLC) technology. The proposed system includes tri-chromatic white LEDs with the red and blue chips modulated at different frequencies and a pinpin photodetector with selective spectral sensitivity. The optoelectronic properties of the optical sources and photodetector device are analyzed. The photodetector device consists two pin structures based on a-SiC:H and a-Si:H with geometrical configuration optimized for the detection of short and large wavelengths in the visible range. Its sensitivity is externally tuned by steady state optical bias. The localization algorithm makes use of the Fourier transform to identify the frequencies present in the photocurrent signal and the wavelength filtering properties of the sensor under front and back optical bias to detect the existing red and blue signals. The viability of the system is demonstrated through the implementation of an automatic algorithm to infer the photodetector cardinal direction.

Performance of CSK Scheme for V2I Visible Light Communication

These days, research related to Intelligent Transportation System (ITS) technology is being widely considered. ITS is inevitable for future transportation systems to reduce accidents, congestion, and offer a smooth flow of traffic. The use of Visible Light Communication (VLC) in ITS systems has been considered widely because of its EMC/EMI free and LED infrastructure reusable properties. Among the VLC schemes, this study analyzed the performance of the Color Shift Keying (CSK) scheme under a Vehicle-to-Infrastructure (V2I) downlink scenario to verify the capability of CSK as a communication tool for ITS. By modeling daylight noise using the modified Blackbody radiation model, this study examined the performance of V2I VLC under daytime conditions. The relationship between BER, the communication distance, and the amount of ambient-light noises under the pre-described V2I scenario were determined by simulations.

Impact of lighting requirements on VLC systems

Advances in solid-state lighting (SSL) are enabling LEDs to be the dominant source for future human-made light. The adoption of LEDs is expected to significantly reduce energy consumption and facilitate precise intensity and color control of illuminated spaces. SSL also makes possible the use of visible light communications (VLC), in which data are emitted from luminaires through subtle intensity variations. This article focuses on the impact of lighting requirements on VLC systems, especially as found in indoor deployment scenarios. We also consider dimming control and its impact on color quality in the context of measured vs. perceived light levels.

Evaluation of visible light communication channel delay profiles for automotive applications

Abstract In this article, we present channel delay profiles based on simulated data regarding the practical conditions for the use of visible light communication (VLC) in automotive applications such as Intelligent Transportation Systems (ITS). Practical vehicular LED headlamp and street lamp that consider the lighting regulation for transportation are used to design the ITS scenarios based on VLC. We modeled two usage scenarios, crossroad and metropolitan street, using the CATIA V5 tool. Measurements for the VLC channel delay profile evaluation were then gathered by using a ray-tracing scheme employing commercial LightTools software under the vehicle-to-vehicle and vehicle-to-infrastructure (V2I) communication links. From the obtained channel impulse responses from both scenarios, we derived the VLC channel delay profiles. From them, we found that the common property of the delay profile was composed of dominant multiple line of sight (LOS) links and a less number of non-LOS delay taps. However, the channel delay profile for the V2I link and metropolitan scenario show more dispersive channel characteristics due to the reflection and diffusion of the visible light.