Multiuser Transmit Precoding Design for Dimming Compatible Visible Light Communications

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).

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

Electronics ◽

10.3390/electronics10080948 ◽

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.

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An Efficient Data Transmission with GSM-MPAPM Modulation for an Indoor VLC System

Symmetry ◽

10.3390/sym11101232 ◽

2019 ◽

Vol 11 (10) ◽

pp. 1232 ◽

Cited By ~ 2

Author(s):

Bao ◽

Hsu ◽

Keyword(s):

Visible Light ◽

Short Distance ◽

Pulse Width Modulation ◽

Pulse Amplitude ◽

Visible Light Communication ◽

Spatial Modulation ◽

Theoretical Scheme ◽

Error Ratio ◽

Bit Error Ratio ◽

Dimming Control

As an emerging wireless communication technique, visible light communication is experiencing a boom in the global communication field, and the dream of accessing to the Internet with light is fast becoming a reality. The objective of this study was to put forward an efficient and theoretical scheme that is based on generalized spatial modulation to reduce the bit error ratio in indoor short-distance visible light communication. The scheme was implemented while using two steps in parallel: (1) The multi-pulse amplitude and the position modulation signal were generated by combining multi-pulse amplitude modulation with multi-pulse position modulation using transmitted information, and (2) certain light-emitting diodes were activated by employing the idea of generalized spatial modulation to convey the generated multi-pulse amplitude and position modulation optical signals. Furthermore, pulse width modulation was introduced to achieve dimming control in order to improve anti-interference ability to the ambient light of the system. The two steps above involved the information theory of communication. An embedded hardware system, which was based on the C8051F330 microcomputer and included a transmitter and a receiver, was designed to verify the performance of this new scheme. Subsequently, the verifiability experiment was carried out. The results of this experiment demonstrated that the proposed theoretical scheme of transmission was feasible and could lower the bit error ratio (BER) in indoor short-distance visible light communication while guaranteeing indoor light quality.

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

Wireless Communications and Mobile Computing ◽

10.1155/2017/4094096 ◽

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.

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Modeling and Analysis of DIPPM: A New Modulation Scheme for Visible Light Communications

Journal of Sensors ◽

10.1155/2015/963296 ◽

2015 ◽

Vol 2015 ◽

pp. 1-8 ◽

Cited By ~ 5

Author(s):

Sana Ullah Jan ◽

Young-Doo Lee ◽

Insoo Koo

Keyword(s):

Visible Light ◽

Direct Detection ◽

Visible Light Communication ◽

Modulation Scheme ◽

Light Sources ◽

Visible Light Communications ◽

Error Performance ◽

Communication Performance ◽

Modeling And Analysis ◽

Dimming Control

Visible Light Communication (VLC) uses an Intensity-Modulation and Direct-Detection (IM/DD) scheme to transmit data. However, the light source used in VLC systems is continuously switched on and off quickly, resulting in flickering. In addition, recent illumination systems include dimming support to allow users to dim the light sources to the desired level. Therefore, the modulation scheme for data transmission in VLC system must include flicker mitigation and dimming control capabilities. In this paper, the authors propose a Double Inverse Pulse Position Modulation (DIPPM) scheme that minimizes flickering and supports a high level of dimming for the illumination sources in VLC systems. To form DIPPM, some changes are made in the symbol structure of the IPPM scheme, and a detailed explanation and mathematical model of DIPPM are given in this paper. Furthermore, both analytical and simulation results for the error performance of 2-DIPPM are compared with the performance of VPPM. Also, the communication performance of DIPPM is analyzed in terms of the normalized required power.

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Capacity analysis for pulse amplitude modulated visible light communications with dimming control

Journal of the Optical Society of America A ◽

10.1364/josaa.31.000561 ◽

2014 ◽

Vol 31 (3) ◽

pp. 561 ◽

Cited By ~ 12

Author(s):

Jin-Yuan Wang ◽

Jun-Bo Wang ◽

Nuo Huang ◽

Ming Chen

Keyword(s):

Visible Light ◽

Pulse Amplitude ◽

Capacity Analysis ◽

Visible Light Communications ◽

Dimming Control

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

Applied Sciences ◽

10.3390/app9010001 ◽

2018 ◽

Vol 9 (1) ◽

pp. 1 ◽

Cited By ~ 4

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.

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Color-Independent Visible Light Communications Based on Color Space: State of the Art and Potentials

Electronics ◽

10.3390/electronics7090190 ◽

2018 ◽

Vol 7 (9) ◽

pp. 190 ◽

Cited By ~ 3

Author(s):

Tae-Ho Kwon ◽

Jai-Eun Kim ◽

Youn-Hee Kim ◽

Ki-Doo Kim

Keyword(s):

Visible Light ◽

Mimo System ◽

Color Space ◽

Past Research ◽

Visible Light Communication ◽

Color Variation ◽

Target Color ◽

Visible Light Communications ◽

Potential Applicability ◽

Dimming Control

Color independency is an important factor in visible light communication (VLC) systems. This paper aims to review and summarize recent achievements in color-independent visible light communication based on color space, with the main focus being on color-space-based modulation (CSBM), termed as generalized color modulation (GCM), which allows VLC to adapt to any target color. The main advantages of GCM are its color independency, reasonable bit error rate (BER) performance during color variation, and dimming control. We also address our past research works that aimed to achieve a color-independent visual MIMO system by incorporating the advantages of GCM, which can lead to higher data rates over longer distances and improved performance, using image processing in addition to color independency. Finally, two case studies are introduced to demonstrate the potential applicability of a color-independent visual-MIMO system using color-space-based modulation techniques.

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

International Journal of Scientific Research in Computer Science Engineering and Information Technology ◽

10.32628/cseit1838108 ◽

2019 ◽

pp. 30-37 ◽

Cited By ~ 2

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.

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Design of Ethernet-VLC Data Conversion System Based on FPGA

International Journal of Computer Theory and Engineering ◽

10.7763/ijcte.2020.v12.1266 ◽

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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