scholarly journals Polymer colour converter with very high modulation bandwidth for visible light communications

2017 ◽  
Vol 5 (35) ◽  
pp. 8916-8920 ◽  
Author(s):  
D. A. Vithanage ◽  
A. L. Kanibolotsky ◽  
S. Rajbhandari ◽  
P. P. Manousiadis ◽  
M. T. Sajjad ◽  
...  
Keyword(s):  
Visible Light ◽  
High Speed ◽  
Visible Light Communication ◽  
Modulation Bandwidth ◽  
Visible Light Communications ◽  
Semiconducting Polymer ◽  
High Modulation ◽  
Very High

We report the synthesis, photophysics and application of a novel semiconducting polymer as a colour converter for high speed visible light communication.

Researching the Information of Transmission Technology Based on Traffic Lights

2014 ◽  
Vol 644-650 ◽  
pp. 4538-4541
Author(s):  
Qiang Li ◽  
Xin Rui Zhang
Keyword(s):  
Visible Light ◽  
Image Recognition ◽  
Communication Technology ◽  
High Speed ◽  
Visible Light Communication ◽  
Qr Code ◽  
Visible Light Communications ◽  
Traffic Light ◽  
Traffic Lights ◽  
Very High

This design is based on Visible Light Communication Technology, to achieve outdoor visible light communications and image recognition etc. through traffic lights. It will play a role on promoting the utilization of traffic lights. The system uses a LED dot matrix to imitate the traffic light, loading QR Code information on the LED dot matrix and then transporting it in a very high-speed flashing. In receiving terminal, first, webcam OV7670 collects information which from the LED dot matrix, then conveys the picture to FPGA, which is the processor. FPGA will handle the picture by gray scale processing, medium filtering and binary processing at last. Thus, the picture from the LED dot matrix will change to ‘0’ and ‘1’ in binary area. Secondly, as there’s a relationship between LED dot matrix and webcam pixels, we can count how many pixels represent one LED. Finally, we can decode the QR Code based on its own style, and display the final result on the TFT screen.

scholarly journals Experimental Demonstration of Special-Shaped 32-Quadrature Amplitude Modulation Constellations for Visible Light Communications

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Xinyue Guo ◽  
Shuangshuang Li ◽  
Yang Guo
Keyword(s):  
Visible Light ◽  
Amplitude Modulation ◽  
High Speed ◽  
Light Emitting Diode ◽  
Rapid Development ◽  
Average Power ◽  
Visible Light Communication ◽  
Quadrature Amplitude Modulation ◽  
Visible Light Communications ◽  
Transmission Distance

With the rapid development of light-emitting diode, visible light communication (VLC) has become a candidate technology for the next generation of high-speed indoor wireless communication. In this paper, we investigate the performance of the 32-quadrature amplitude modulation (32-QAM) constellation shaping schemes for the first time, where two special circular constellations, named Circular (4, 11, 17) and Circular (1, 5, 11, 15), and a triangular constellation are proposed based on the Shannon’s criterion. Theoretical analysis indicates that the triangular constellation scheme has the largest minimum Euclidian distance while the Circular (4, 11, 17) scheme achieves the lowest peak-to-average power ratio (PAPR). Experimental results show that the bit error rate performance is finally decided by the value of PAPR in the VLC system due to the serious nonlinearity of the LED, where the Circular (4, 11, 17) scheme always performs best under the 7% preforward error correction threshold of 3.8 × 10−3 with 62.5Mb/s transmission data rate and 1-meter transmission distance.

Analysis of InGaN Multiple-Quantum-Well Photoelectric Device of Visible Light Communication

2020 ◽  
Vol 15 (7) ◽  
pp. 909-916
Author(s):  
Haitao Chi ◽  
Yu Du ◽  
Gongyu Li
Keyword(s):  
Quantum Well ◽  
Visible Light ◽  
High Speed ◽  
Visible Light Communication ◽  
Multiple Quantum ◽  
Modulation Bandwidth ◽  
Carrier Distribution ◽  
Photoelectric Device ◽  
Electron Leakage ◽  
Modulation Speed

The key to achieving high-speed and high-quality visible light communication is to increase the modulation speed of Light-Emitting Diode (LED). Therefore, in this study, the influence of the Composite Mechanism of Carrier (CMC) on the modulation speed of LED is studied by designing different structures of the InGaN Multi-quantum-well (MQW) LED active region. Because the carrier subspace waves function of narrow quantum well LED overlaps more frequently and the electron leakage effect is more significant, the compound rate is faster and the modulation bandwidth is higher. InGaN quantum barrier LED with a content of 1% can increase the weight of radiation recombination, which makes the modulation bandwidth higher than GaN quantum barrier LEDs; when the in content is 5%, electron leakage and Auger recombination have a dominant position. Moreover, because these two compounding mechanisms have a fast compounding rate, the modulation bandwidth is significantly increased. Then the 405 nm laser-excited photoluminescence (PL) is introduced to analyze the carrier dynamics in the LED and obtain the related processes of carrier distribution and transport. The proposed carrier microscopic model can well explain change characteristics of the PL luminescence peak, luminous intensity, and half-height width of InGaN/GaN MQW LED with different excitation wavelengths. At low temperature, the PL peak of the InGaN/GaN quantum well LED redshifts with the increase of temperature, because the weakly bound carrier transfers the obtained energy to the deeply bound energy level of high In content.

scholarly journals Carrierless amplitude and phase modulation in wireless visible light communication systems

2020 ◽  
Vol 378 (2169) ◽  
pp. 20190181 ◽  
Author(s):  
N. Bamiedakis ◽  
R. V. Penty ◽  
I. H. White
Keyword(s):  
Visible Light ◽  
Communication Systems ◽  
High Speed ◽  
Low Cost ◽  
Visible Light Communication ◽  
Practical Implementation ◽  
Visible Light Communications ◽  
Modulation Formats ◽  
Spectrally Efficient ◽  
Basic Features

Visible light communications (VLCs) have attracted considerable interest in recent years owing to the potential to simultaneously achieve data transmission and illumination using low-cost light-emitting diodes (LEDs). However, the high-speed capability of such links is typically limited by the low bandwidth of LEDs. As a result, spectrally efficient advanced modulation formats have been considered for use in VLC links in order to mitigate this issue and enable higher data rates. Carrierless amplitude and phase (CAP) modulation is one such spectrally efficient scheme that has attracted significant interest in recent years owing to its good potential and practical implementation. In this paper, we introduce the basic features of CAP modulation and review its use in the context of indoor VLC systems. We describe some of its attributes and inherent limitations, present related advances aiming to improve its performance and potential and report on recent experimental demonstrations of LED-based VLC links employing CAP modulation. This article is part of the theme issue ‘Optical wireless communication’.

scholarly journals Hardware Architectures of Visible Light Communication Transmitter and Receiver for Beacon-based Indoor Positioning Systems

2019 ◽  
Author(s):  
Phuc Duc Nguyen
Keyword(s):  
Visible Light ◽  
High Speed ◽  
Large Scale ◽  
Response Times ◽  
Vlsi Architecture ◽  
Visible Light Communication ◽  
Visible Light Communications ◽  
Soft Decision ◽  
Soft Decoding ◽  
Positioning Systems

High-speed applications of Visible Light Communications have been presented recently in which response times of photodiode-based VLC receivers are critical points. Typical VLC receiver routines, such as soft-decoding of run-length limited (RLL) codes and FEC codes was purely processed on embedded firmware, and potentially cause bottleneck at the receiver. To speed up the performance of receivers, ASIC-based VLC receiver could be the solution. Unfortunately, recent works on soft-decoding of RLL and FEC have shown that they are bulky and time-consuming computations. This causes hardware implementation of VLC receivers becomes heavy and unrealistic. In this paper, we introduce a compact Polar-code-based VLC receivers. in which flicker mitigation of the system can be guaranteed even without RLL codes. In particular, we utilized the centralized bit-probability distribution of a pre-scrambler and a Polar encoder to create a non-RLL flicker mitigation solution. At the receiver, a 3-bit soft-decision filter was implemented to analyze signals received from the VLC channel to extract log-likelihood ratio (LLR) values and feed them to the Polar decoder. Therefore, the proposed receiver could exploit the soft-decoding of the Polar decoder to improve the error-correction performance of the system. Due to the non-RLL characteristic, the receiver has a preeminent code-rate and a reduced complexity compared with RLL-based receivers. We present the proposed VLC receiver along with a novel very-large-scale integration (VLSI) architecture, and a synthesis of our design using FPGA/ASIC synthesis tools.

scholarly journals Energy-Efficient Optimization Design for the Multi-Color LED Based Visible Light Communication Systems under Illumination Constraints

2018 ◽  
Vol 9 (1) ◽  
pp. 1 ◽  
Author(s):  
Yu Zuo ◽  
Jian Zhang
Keyword(s):  
Energy Consumption ◽  
Visible Light ◽  
Power Allocation ◽  
Communication Systems ◽  
Optimization Design ◽  
Optical Power ◽  
Visible Light Communication ◽  
Visible Light Communications ◽  
Allocation Scheme ◽  
High Modulation

Visible light communications (VLCs) utilizing multi-color light-emitting diodes (LEDs) can achieve a high modulation bandwidth and high-quality illumination compared with phosphor-converted LEDs, which have attracted much attention. However, the spectrum overlapping of different colors may cause the crosstalk problem, which should be considered in the practical multi-color LED-based VLC systems. Due to the ever-increasing energy consumption, the interest in an energy-saving communication technique has further increased. In this paper, in order to maximize energy efficiency, an optimization problem of the optical power allocation scheme is formulated for the multi-color LED-based VLC systems under the necessary communication requirements and illumination constraints with luminance, chromaticity, and signal to interference plus noise ratio (SINR) constraints. Simulation results indicate that the proposed optimal power allocation scheme can reduce energy consumption while satisfying the illumination and communication requirements.

scholarly journals Micro-LED as a Promising Candidate for High-Speed Visible Light Communication

2020 ◽  
Vol 10 (20) ◽  
pp. 7384
Author(s):  
Konthoujam James Singh ◽  
Yu-Ming Huang ◽  
Tanveer Ahmed ◽  
An-Chen Liu ◽  
Sung-Wen Huang Chen ◽  
...  
Keyword(s):  
Power Consumption ◽  
Low Power ◽  
Visible Light ◽  
High Speed ◽  
Review Paper ◽  
Visible Light Communication ◽  
Low Power Consumption ◽  
Active Layer Thickness ◽  
Modulation Bandwidth ◽  
Recombination Time

Visible Light Communication (VLC) technology is an emerging technology using visible light modulation that, in the modern world, will mainly facilitate high-speed internet connectivity. VLC provides tremendous advantages compared to conventional radio frequency, such as a higher transmission rate, high bandwidth, low-power consumption, no health hazards, less interference, etc., which make it more prominent in recent days. Due to their outstanding features, including low cost, low power consumption, etc., µ-light-emitting diodes (LEDs) have gained considerable attention for VLC implementation, but mostly for the ability to be used for lighting as well as communications. In this review paper, we will focus mainly on recent developments in VLC applications and various factors affecting the modulation bandwidth of VLC devices. Numerous factors, such as quantum confined stark effect (QCSE), carrier lifetime, carrier recombination time, crystal orientation, etc. affect the modulation bandwidth of LEDs, and more information will be discussed in the following sections. This paper will focus on VLC applications based on LEDs but mainly on semipolar μ-LEDs and μ-LED-based arrays with high bandwidths. Another important application of VLC is underwater optical wireless communication (UOWC), which has drawn a huge interest in marine exploration and underwater connectivity, but still faces some challenges because visible light is being used. In addition, this paper will focus on how the current VLC system modulation bandwidth can be enhanced. Many methods have been introduced, such as decreasing the active layer thickness or effective active area or using doping, but the bandwidth is restricted by the recombination time when the system configuration reaches its limit. Therefore, it is important to find alternative ways such as optimizing the system, using the blue filter or using the equalization technology, which will be addressed later. Overall, this review paper provides a brief overview of the VLC-based system performance and some of its potential prospects.

scholarly journals Li-Fi the Next Generation of Wireless Communication through Visible Light Communication (VLC) Technology

2019 ◽  
pp. 30-37 ◽  
Author(s):  
Imran Siddique ◽  
Muhammad Zubair Awan ◽  
Muhammad Yousaf Khan ◽  
Azhar Mazhar
Keyword(s):  
Wireless Communication ◽  
Visible Light ◽  
Communication System ◽  
High Speed ◽  
Wave Spectrum ◽  
Visible Light Communication ◽  
Visible Light Communications ◽  
Light Emitting ◽  
Wide Range ◽  
Advance Research

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.

scholarly journals Design of Ethernet-VLC Data Conversion System Based on FPGA

2020 ◽  
Vol 12 (3) ◽  
pp. 69-73
Author(s):  
Guiling Sun ◽  
◽  
Weijian Zhao ◽  
Ruobin Wang ◽  
Xuanjie Li
Keyword(s):  
Visible Light ◽  
High Speed ◽  
Visible Light Communication ◽  
Data Conversion ◽  
Visible Light Communications ◽  
Data Buffer ◽  
Wide Range ◽  
Conversion System ◽  
Buffer Control ◽  
Ethernet Interface

Visible light communication (VLC) has attracted people's attention due to its wide range of spectrum resources and good privacy in recent year. But research on visible light communication is mostly focused on LED materials, transfer protocol, transmission rates, etc. Lack of research that connect the visible light communications with existing communications methods. In this paper, we propose an Ethernet-visible data conversion system based on FPGA, including Ethernet interface logic, bit-width conversion logic, data buffer logic, and visible light communication transceiver logic. The proposed system achieves Ethernet and visible light access, and realizes 1000Mbps Ethernet data and 625Mbps visible light data conversion. Through buffer control, Ethernet data can be completely and reliably transmitted from high speed to low speed. By defining the structure of visible light communication frame and adding data self-recovery mechanism, data transmission has higher stability on the path of visible light. The feasibility of the system is proved by actual measurements.

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