scholarly journals Analysis of synchronous interpolated signals in Tactical Sensor Network-Visible light communication (TSN-VLC) link

2021 ◽  
Vol 23 (06) ◽  
pp. 196-203
Author(s):  
Atul Ranjan Srivastava ◽  
◽  
Amit Kumar Sharma ◽  
Gaurav Sharma ◽  
Neha Sharma ◽  
...  
Keyword(s):  
Visible Light ◽  
Sensor Network ◽  
Visible Light Communication ◽  
Sampling Frequency ◽  
Signal Spectrum ◽  
Light Sources ◽  
Transmission Performance ◽  
Interpolation Filter ◽  
Sampling Frequency Offset ◽  
Frequency Components

Sampling frequency offset (SFO) is an important issue in the tactical sensor network (TSN) based visible light communication (VLC) systems in Tactical Sensor Network. A digital interpolation can be used to effectively compensate the SFO. In such case, oversampling at the receiver ADC is required to mitigate the aliasing effect due to imperfect DACs and nonlinearity of visible light sources that cause extra frequency components inside/outside the signal spectrum. The oversampling factor is mainly determined by the order of the digital interpolation filter and TSN links. The design of the TSN-VLC receiver incorporating the digital interpolation filter is vital as it affects not only the transmission performance but also the complexity of signal processing. To evaluate the feasibility of the digital interpolation-based SFO compensation schemes for cost-sensitive TSN applications. Based on the real-time VLC tactical sensor network, the comparison in the VLC-TSN transmission performance and DSP complexity between different interpolation-based SFO compensation schemes is analyzed.

scholarly journals Narrow Linewidth Distributed Bragg Reflectors Based on InGaN/GaN Laser

Micromachines ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 529 ◽  
Author(s):  
Xie ◽  
Li ◽  
Liao ◽  
Deng ◽  
Wang ◽  
...  
Keyword(s):  
Gallium Nitride ◽  
Visible Light ◽  
Communication Systems ◽  
Fdtd Method ◽  
Visible Light Communication ◽  
Bragg Reflector ◽  
Duty Ratio ◽  
Light Sources ◽  
Distributed Bragg Reflector ◽  
Dbr Lasers

A variety of emerging technologies, such as visible light communication systems, require narrow linewidths and easy-to-integrate light sources. Such a requirement could be potentially fulfilled with the distributed Bragg reflector (DBR) lasers, which are also promising for the monolithical integration with other optical components. The InGaN/GaN-based surface etched DBR is designed and optimized using the finite-difference-time-domain (FDTD) method to obtain very narrow-band reflectors that can serve as a wavelength filter. The results reveal that the ultimate reflectivity depends on the grating period and duty ratio of the DBR. Based on the design, the DBR lasers with various duty ratios are fabricated, specifically, the 19th, 13th and 3rd order DBR grating with duty ratio set as 50%/75%/95%. The minimum linewidth could be achieved at 0.45 nm from the 19th order grating with a 75% duty ratio. For comparison, the Fabry–Pérot (F–P) based on the same indium gallium nitride/gallium nitride (InGaN/GaN) epitaxial wafer are fabricated. The full width at half maximum (FWHM) of the DBR laser shrank by 65% compared to that of the conventional F–P laser, which might be helpful in the application of the visible light communication system.

scholarly journals Recent Advances in Indoor Localization via Visible Lights: A Survey

Sensors ◽  
2020 ◽  
Vol 20 (5) ◽  
pp. 1382 ◽  
Author(s):  
A B M Mohaimenur Rahman ◽  
Ting Li ◽  
Yu Wang
Keyword(s):  
Visible Light ◽  
Indoor Localization ◽  
Low Cost ◽  
Visible Light Communication ◽  
Light Sources ◽  
Smart Building ◽  
Recent Advances ◽  
Radio Signals ◽  
Indoor Scenarios ◽  
Indoor Spaces

Because of the limitations of the Global Positioning System (GPS) in indoor scenarios, various types of indoor positioning or localization technologies have been proposed and deployed. Wireless radio signals have been widely used for both communication and localization purposes due to their popular availability in indoor spaces. However, the accuracy of indoor localization based purely on radio signals is still not perfect. Recently, visible light communication (VLC) has made use of electromagnetic radiation from light sources for transmitting data. The potential for deploying visible light communication for indoor localization has been investigated in recent years. Visible-light-based localization enjoys low deployment cost, high throughput, and high security. In this article, the most recent advances in visible-light-based indoor localization systems have been reviewed. We strongly believe that visible-light-based localization will become a low-cost and feasible complementary solution for indoor localization and other smart building applications.

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

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
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.

Dimming controlled multi header pulse position modulation (MH-PPM) for visible light communication system

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sandip Das ◽  
Soumitra Kumar Mandal
Keyword(s):  
Visible Light ◽  
Data Transmission ◽  
Input Data ◽  
Visible Light Communication ◽  
Experimental Results ◽  
Pulse Position Modulation ◽  
Light Sources ◽  
Error Performance ◽  
Control Scheme ◽  
Dimming Control

Abstract Visible light communication (VLC) has recently drawn more attention due to the existing light sources having a bandwidth that can deliver data transmission at higher bit rates. To maintain desired brightness levels along with reliable data transmission, VLC requires to control dimming levels. In this paper, a dimming control scheme based on pulse position modulation (PPM) is proposed, which constructs a dimming encoded frame per symbol of input data. The scheme utilizes multiple headers, which is selected depending on the dimming levels and the number of bits in a symbol of input data. The proposed scheme for the VLC system supports various dimming levels. The multi header PPM frame generation for input data K = 4 $K=4$ and dimming values α = 0.25, 0.375, and 0.5 is simulated using NI Labview. The proposed dimming scheme has an excellent short-run length property which is well under the maximum flickering time period and is thus capable of flicker mitigation. The slot error performance of the proposed dimming control scheme in a VLC system for varying dimming levels is simulated in Matlab. Simulation results show that the proposed scheme has excellent error performance for a low dimming value of α = 0.25. The experimental results are also carried out in the optisystem considering the practical measured parameters of the indoor environment for free space channel and simulating the VLC system for the proposed scheme. The simulation is carried for different data rates over varying link ranges and the experimental results show that the proposed scheme performs best when dimming value α = 0.25 and data rate 2 Gbps.

DATA COMMUNICATION USING VISIBLE LIGHT

2015 ◽  
Vol 3 (5) ◽  
pp. 358-362
Author(s):  
Tyran Kinny ◽  
Franklin Puthuva ◽  
Ashore Komban ◽  
Dipti Belekar
Keyword(s):  
Visible Light ◽  
Low Cost ◽  
Data Communication ◽  
Visible Spectrum ◽  
Visible Light Communication ◽  
Light Sources ◽  
Human Eye ◽  
Data Rates ◽  
Communication Devices ◽  
Normal Light

Visible Light Communication (VLC) using a Light Fidelity system, as proposed by a German physicist—Harald Haas, provides transmission of data through illumination by sending data through an LED light source that varies in intensity that can be controlled and adjusted such that it appears as normal light to the naked human eye. Here the property of persistence of vision of the human eye is exploited for additional application of a free, sustainable and green source that can be used for wireless communication at very fast data rates. This paper focuses on developing a low cost Li-Fi based system and analyses its performance with respect to existing wireless technology. Wi-Fi is great for general wireless coverage within buildings, whereas Li-Fi is ideal for high density wireless data coverage in confined area and for relieving radio interference issues. Li-Fi based system provides better bandwidth, efficiency, availability and security than Wi-Fi and has already achieved higher data rates. By leveraging the low-cost nature of LEDs and lighting units there are many opportunities to exploit this medium, from public internet access through day-to-day light sources which have their primary purpose of only emitting light. This project envisions a future where data for communication devices will be transmitted through the visible spectrum thus de-clogging the currently overused RF spectrum.

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