scholarly journals Ambient LED Light Noise Reduction Using Adaptive Differential Equalization in Li-Fi Wireless Link

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1060
Author(s):  
Yong-Yuk Won ◽  
Sang Min Yoon ◽  
Dongsun Seo
Keyword(s):  
Forward Error Correction ◽  
First Generation ◽  
Weighting Function ◽  
Signal To Noise Ratio ◽  
Light Emitting Diode ◽  
Light Sources ◽  
Ambient Light ◽  
Light Emitting ◽  
Reduction Efficiency ◽  
Forward Error

For Li-Fi wireless links based on a white light emitting diode, an adaptive differential equalization (ADE) technique that reduces various noises such as interference noise and shot one generated from ambient light sources is pro-posed. The ADE technique reduces noise by taking advantage of the fact that the derivative between adjacent sampling points of signal with digital waveform is very different from that of noise with the random analog waveform. Furthermore, a weighting function that reflects the Poisson characteristics of shot noise is applied to the ADE technique in order to maximize the reduction efficiency of ambient noise. The signal-to-noise ratio of input non-return-to-zero-on–off keying (NRZ-OOK) signal is improved by 7.5 dB at the first-generation forward error correction (FEC) threshold (the bit error rate (BER) of 8 × 10−5) using the optical wireless experimental link. In addition, it is confirmed that it is possible to maintain the transmission performance corresponding to the BER of 1 × 10−5 by using the proposed ADE technique, even when the intensity of the ambient light source increases by 6 dB.

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.

Electrically driven single microribbon based near-infrared exciton-polariton light-emitting diode

CrystEngComm ◽  
2021 ◽  
Author(s):  
Mingming Jiang ◽  
Fupeng Zhang ◽  
Kai Tang ◽  
Peng Wan ◽  
Caixia Kan
Keyword(s):  
High Performance ◽  
Near Infrared ◽  
Light Emitting Diodes ◽  
Light Emitting Diode ◽  
Light Sources ◽  
Coherent Light ◽  
Light Emitting ◽  
Exciton Polaritons ◽  
Laser Devices

Achieving electrically-driven exciton-polaritons has drawn substantial attention toward developing ultralow-threshold coherent light sources, containing polariton laser devices and high-performance light-emitting diodes (LEDs). In this work, we demonstrate an electrically driven...

Reliability of High-Power Light Emitting Diode Attached With Different Thermal Interface Materials

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Xin Li ◽  
Xu Chen ◽  
Guo-Quan Lu
Keyword(s):  
High Power ◽  
Heat Dissipation ◽  
Light Emitting Diode ◽  
Temperature Cycling ◽  
Fluorescent Light ◽  
Light Sources ◽  
Light Emitting ◽  
Die Attach ◽  
Nanosilver Paste ◽  
Interconnection Material

As a solid electroluminescent source, white light emitting diode (LED) has entered a practical stage and become an alternative to replace incandescent and fluorescent light sources. However, due to the increasing integration and miniaturization of LED chips, heat flux inside the chip is also increasing, which puts the packaging into the position to meet higher requirements of heat dissipation. In this study, a new interconnection material—nanosilver paste is used for the LED chip packaging to pursue a better optical performance, since high thermal conductivity of this material can help improve the efficiency of heat dissipation for the LED chip. The bonding ability of this new die-attach material is evaluated by their bonding strength. Moreover, high-power LED modules connected with nanosilver paste, Sn3Ag0.5Cu solder, and silver epoxy are aged under hygrothermal aging and temperature cycling tests. The performances of these LED modules are tested at different aging time. The results show that LED modules sintered with nanosilver paste have the best performance and stability.

In-Use Photostability Practice and Regulatory Evaluation for Pharmaceutical Products in an Age of Light-Emitting Diode Light Sources

2019 ◽  
Vol 108 (3) ◽  
pp. 1172-1176 ◽  
Author(s):  
Leonardo R. Allain ◽  
Brittany C. Pierce ◽  
W. Peter Wuelfing ◽  
Allen C. Templeton ◽  
Roy Helmy
Keyword(s):  
Light Emitting Diode ◽  
Pharmaceutical Products ◽  
Light Sources ◽  
Light Emitting ◽  
Regulatory Evaluation

Manufacture and Evaluation of Light Emitting Diode Package Substrate Using Flexible Printed Circuit Board

2015 ◽  
Vol 15 (10) ◽  
pp. 7578-7581
Author(s):  
Jung-Kab Park ◽  
Jin-Ha Shin ◽  
Mun-Gi Jung ◽  
Tomabechi Shigehisa ◽  
Hwa-Sun Park ◽  
...  
Keyword(s):  
Thermal Resistance ◽  
Light Emitting Diode ◽  
Thermal Conductance ◽  
Polyimide Film ◽  
Luminous Efficiency ◽  
Circuit Board ◽  
Light Sources ◽  
Thermal Shock Test ◽  
Light Emitting ◽  
Au Electrode

Unlike other light sources such as fluorescent lamps and incandescent bulbs, light-emitting diodes (LED) convert 70∼80% of energy into heat. If the heat produced an LED chip is not effectively released, its luminous efficiency and lifespan are reduced. Therefore, as a method effectively release heat, an LED PKG substrate containing a heat-releasing material with excellent thermal conductance was fabricated, and its thermal resistance and luminous efficiency were analyzed. In this experiment, a thin polyimide film with excellent ductility was used to fabricate the LED PKG substrate. A 35-μm-thick Cu foil with excellent thermal conductance was subjected to high temperature and pressure and attached to both sides of the polyimide film. By electroplating Ag or Au, which has excellent thermal conductance, for us as the electrode and heat-releasing material, LED PKG substrate was fabricated with a thickness of approximately 170 μm. (−40 °C → RT → 120 °C). The results revealed that the LED PKG substrate having a Ag electrode with excellent thermal conductance had an excellent thermal resistance of approximately 4.2 °C/W (Au electrode: 5.6 °C/W). The luminous flux after 100 cycles in the thermal shock test was reduced by approximately 0.09% (Au electrode: 2.77%), indicating that the LED PKG substrate had excellent thermal resistance without any mechanical and material defects in a rapid-temperature-changing environment. The advantages and excellent thermal resistance can be exploited in cellular phones and LCD panels, and heat-releasing problems in thin panels be solved.

Research on the Nonlinearity of Photoelectric Pyrometer Based on Light-Emitting Diode Light Sources

2010 ◽  
Vol 30 (8) ◽  
pp. 2412-2416 ◽  
Author(s):  
董伟 Dong Wei ◽  
原遵东 Yuan Zundong ◽  
卢小丰 Lu Xiaofeng
Keyword(s):  
Light Emitting Diode ◽  
Light Sources ◽  
Light Emitting ◽  
Photoelectric Pyrometer

scholarly journals A Full-Duplex LED-to-LED Visible Light Communication System

Electronics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1713
Author(s):  
Hyunwoo Jung ◽  
Sung-Man Kim
Keyword(s):  
Visible Light ◽  
Bit Error Rate ◽  
Error Rate ◽  
Signal To Noise Ratio ◽  
Light Emitting Diode ◽  
Visible Light Communication ◽  
Full Duplex ◽  
Signal To Noise ◽  
Light Emitting ◽  
Half Duplex

We experimentally demonstrated full-duplex light-emitting diode (LED)-to-LED visible light communication (VLC) using LEDs as the transmitter and receiver. Firstly, we investigated the performance dependency on the wavelengths of the LED transmitter and receiver by measuring the rise time and signal-to-noise ratio (SNR). Through the investigation, we were able to choose the optimal LED color set for LED-to-LED VLC using Shannon’s channel capacity law. The bit error rate (BER) results of full-duplex and half-duplex LED-to-LED VLC systems with the optimal LED sets are shown to compare the performance. Furthermore, we discuss major distortions and signal losses in the full-duplex LED-to-LED VLC system.

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