scholarly journals An ANN-Based Adaptive Predistorter for LED Nonlinearity in Indoor Visible Light Communications

Electronics ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 948
Author(s):  
Jenn-Kaie Lain ◽  
Yan-He Chen
Keyword(s):  
Visible Light ◽  
Light Emitting Diode ◽  
Optical Power ◽  
Visible Light Communication ◽  
Universal Function ◽  
Visible Light Communications ◽  
Least Mean Square ◽  
Training Sequences ◽  
Led Nonlinearity ◽  
Electrical Source

By modulating the optical power of the light-emitting diode (LED) in accordance with the electrical source and using a photodetector to convert the corresponding optical variation back into electrical signals, visible light communication (VLC) has been developed to achieve lighting and communications simultaneously, and is now considered one of the promising technologies for handling the continuing increases in data demands, especially indoors, for next generation wireless broadband systems. During the process of electrical-to-optical conversion using LEDs in VLC, however, signal distortion occurs due to LED nonlinearity, resulting in VLC system performance degradation. Artificial neural networks (ANNs) are thought to be capable of achieving universal function approximation, which was the motivation for introducing ANN predistortion to compensate for LED nonlinearity in this paper. Without using additional training sequences, the related parameters in the proposed ANN predistorter can be adaptively updated, using a feedback replica of the original electrical source, to track the LED time-variant characteristics due to temperature variation and aging. Computer simulations and experimental implementation were carried out to evaluate and validate the performance of the proposed ANN predistorter against existing adaptive predistorter schemes, such as the normalized least mean square predistorter and the Chebyshev polynomial predistorter.

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.

scholarly journals Secrecy Dimming Capacity in Multi-LED PAM-Based Visible Light Communications

2017 ◽  
Vol 2017 ◽  
pp. 1-6
Author(s):  
Byung Wook Kim
Keyword(s):  
Visible Light ◽  
Light Emitting Diode ◽  
Mobile Network ◽  
Pulse Amplitude ◽  
Visible Light Communication ◽  
Security And Privacy ◽  
Visible Light Communications ◽  
Light Emitting ◽  
Secure Transmission ◽  
Transmission Ability

Recently, mobile cloud computing (MCC) has gained a lot of interest for researchers building the next-generation mobile applications. Because unauthorized access may cause serious problems, security and privacy with MCC have become significant issues. This paper addresses the secrecy dimming capacity of secure transmission in MCC over visible light communication (VLC) channels. By obtaining the entropy-maximizing symbol probability of multiple light emitting diode- (LED-) based pulse amplitude modulation (PAM), mathematical analysis of the secrecy dimming capacity of VLC was derived. Simulation results show that the secure transmission ability of multi-LED-based VLC is determined according to the number of activated LEDs and target dimming level. This can be a guideline for practical VLC-based mobile network designers intending to secure wireless transmission and to decide on the number of activated LEDs at target dimming level to operate.

scholarly journals Multiuser Transmit Precoding Design for Dimming Compatible Visible Light Communications

2019 ◽  
Vol 9 (6) ◽  
pp. 1147
Author(s):  
Baolong Li ◽  
Xiaomei Xue ◽  
Qiong Wu ◽  
Yang Liu ◽  
Guilu Wu ◽  
...  
Keyword(s):  
Visible Light ◽  
Optical Power ◽  
Pulse Amplitude ◽  
Visible Light Communication ◽  
Visible Light Communications ◽  
Zero Forcing ◽  
Multiuser Interference ◽  
Wide Range ◽  
Dimming Control ◽  
Transmit Precoding

In multiuser visible light communication (VLC) systems, many transmit precoding (TPC) techniques have been investigated to suppress multiuser interference. However, these conventional works restrict their modulation to the special case of zero mean, which inherently limits their application to some popular modulations associated with the non-zero mean in VLC, such as pulse position modulation (PPM). Since the modulation with non-zero mean leads to more intricate optical power constraints and design objective functions than the case of zero mean, the TPC design that can support a general modulation is still an open problem. In the paper, we conceive of a general solution of the TPC scheme combined with dimming control for multiuser VLC systems, which is capable of mitigating multiuser interference, while at the same time, achieving the desired dimming level. The proposed scheme is applicable to a wide range of modulations in VLC, such as pulse amplitude modulation (PAM), PPM, and so on. Simulation results demonstrate that the proposed scheme outperforms the traditional pseudo-inverse-based zero-forcing TPC in terms of bit error rate (BER).

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 Outdoor Visible Light Communication in Intelligent Transportation Systems: Impact of Snow and Rain

2019 ◽  
Vol 9 (24) ◽  
pp. 5453 ◽  
Author(s):  
Reham W. Zaki ◽  
Heba A. Fayed ◽  
Ahmed Abd El Aziz ◽  
Moustafa H. Aly
Keyword(s):  
Visible Light ◽  
Intelligent Transportation Systems ◽  
Light Emitting Diode ◽  
Optical Power ◽  
Visible Light Communication ◽  
Transportation Systems ◽  
Modulation Scheme ◽  
Pulse Position Modulation ◽  
Traffic Light ◽  
Coverage Area

A comprehensive study of outdoor visible light communication (VLC) under snow and rain effects has been conducted in this paper. This paper analyzes the expected rain attenuation of Marshal, Carbonneau, and Japan models at different precipitation levels. Snow attenuation is measured in wet and dry situations at various precipitation levels as well. Therefore, a full comparison is carried out for different attenuation effects on certain outdoor VLC design characteristics such as the maximum signal-to-noise ratio (SNR), optical power received, bit error rate (BER), and maximum coverage area. VLC with various modulation techniques is considered. The ON–OFF Keying (OOK), L-Pulse Position Modulation (L-PPM), Inverse L-Pulse Position Modulation (I-L-PPM), and Subcarrier Binary Phase-Shift Keying (SC-BPSK) are investigated. The simulation results show a considerable difference in the information received under different weather conditions depending on the type of modulation scheme used. The simulation has been done on a two-lane road, and a green traffic light-emitting diode (LED) with a wavelength of 505 nm is used as a transmitter. A non-imaging concentrator coupled with a photodetector is considered to be a cost-effective receiver.

scholarly journals Finger-Gesture Recognition for Visible Light Communication Systems Using Machine Learning

2021 ◽  
Vol 11 (24) ◽  
pp. 11582
Author(s):  
Julian Webber ◽  
Abolfazl Mehbodniya ◽  
Rui Teng ◽  
Ahmed Arafa ◽  
Ahmed Alwakeel
Keyword(s):  
Visible Light ◽  
Gesture Recognition ◽  
Video Processing ◽  
Communication Systems ◽  
High Speed ◽  
Short Term Memory ◽  
Light Transmission ◽  
Light Emitting Diode ◽  
Visible Light Communication ◽  
Visible Light Communications

Gesture recognition (GR) has many applications for human-computer interaction (HCI) in the healthcare, home, and business arenas. However, the common techniques to realize gesture recognition using video processing are computationally intensive and expensive. In this work, we propose to task existing visible light communications (VLC) systems with gesture recognition. Different finger movements are identified by training on the light transitions between fingers using the long short-term memory (LSTM) neural network. This paper describes the design and implementation of the gesture recognition technique for a practical VLC system operating over a distance of 48 cm. The platform uses a single low-cost light-emitting diode (LED) and photo-diode sensor at the receiver side. The system recognizes gestures from interruptions in the direct light transmission, and is therefore suitable for high-speed communication. Gesture recognition accuracies were conducted for five gestures, and results demonstrate that the proposed system is able to accurately identify the gestures in up to 88% of cases.

An approach to ensure joint illumination & communication performance of a forward error corrected indoor visible light communication (VLC) system in presence of ambient light interference

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Sourish Chatterjee ◽  
Biswanath Roy
Keyword(s):  
Visible Light ◽  
Bit Error Rate ◽  
Error Rate ◽  
Light Emitting Diode ◽  
Visible Light Communication ◽  
Ambient Light ◽  
Ambient Illumination ◽  
Communication Performance ◽  
Light Interference ◽  
Forward Error

AbstractIn recent time of looming radio frequency (RF) spectrum crisis, visible light communication using lighting infrastructure emerged as a potential alternative at an indoor environment. This paper addresses the setback associated with ambient light interference in an indoor Visible Light Communication (VLC) system to ensure joint communication and illumination performance inside an office room. A novel VLC architecture with suitable white light emitting diode (WLED) luminaire arrangement is presented to minimize the dispersion of signal to interference plus noise ratio (SINR) across the room. Luminaires are categorized in two groups viz. data transmitting illuminants and illuminants for lighting purpose. The first group is dedicated to transmit data as well as serves the purpose of illumination. The other set creates only ambient illumination to achieve quality lighting attributes. The proposed forward error corrected receiver configuration discards the ambient light noise originated by the illuminants that serve the ambient illumination. Tail biting convolutional encoder and viterbi decoder are used at the encoding section of the transmitter and decoding section of the receiver respectively to improve bit error rate. Results obtained through MATLAB simulation shows better average bit error rate (BER) in the order of 10−8 measured at uniformly distributed 25 grid points over the working plane. At the same time achieved average horizontal illuminance with good uniformity comply with ISO recommendation.

scholarly journals Performance of Vehicular Visible Light Communications under the Effects of Atmospheric Turbulence with Aperture Averaging

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2751
Author(s):  
Elizabeth Eso ◽  
Zabih Ghassemlooy ◽  
Stanislav Zvanovec ◽  
Juna Sathian ◽  
Mojtaba Mansour Abadi ◽  
...  
Keyword(s):  
Visible Light ◽  
Atmospheric Turbulence ◽  
Signal To Noise Ratio ◽  
Light Emitting Diode ◽  
Experimental Investigations ◽  
Visible Light Communications ◽  
Incoherent Light ◽  
Performance Improvements ◽  
Aperture Averaging ◽  
Induced Signal

In this paper, we investigate the performance of a vehicular visible light communications (VVLC) link with a non-collimated and incoherent light source (a light-emitting diode) as the transmitter (Tx), and two different optical receiver (Rx) types (a camera and photodiode (PD)) under atmospheric turbulence (AT) conditions with aperture averaging (AA). First, we present simulation results indicating performance improvements in the signal-to-noise ratio (SNR) under AT with AA with increasing size of the optical concentrator. Experimental investigations demonstrate the potency of AA in mitigating the induced signal fading due to the weak to moderate AT regimes in a VVLC system. The experimental results obtained with AA show that the link’s performance was stable in terms of the average SNR and the peak SNR for the PD and camera-based Rx links, respectively with <1 dB SNR penalty for both Rxs, as the strength of AT increases compared with the link with no AT.

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