Browsing by Author "Wei, Liang-Yu"

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100-m Long Distance RGB Visible Light Camera Communication
(2018-01-01)
Liu, Yen-Chun
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Shiu, Ruei-Jie
;
Wei, Liang-Yu
;
Hsu, Chin-Wei
;
Chow, Chi-Wai
We demonstrate and analyze using different ISO values to achieve a 100-m long distance visible light camera communication using red/green/blue (RGB) light-emitting-diodes (LEDs).
2.333-Tbit/s bi-directional optical mobile networks using optical wireless communication (OWC)
(2020-11-15)
Wei, Liang-Yu
;
Chen, Shu-, I
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Yeh, Chien-Hung
;
Liu, Yang
;
Chen, Guan-Hong
We propose and experimentally demonstrate a 2.333-Tbit/s bi-directional optical mobile network using optical wireless communication (OWC). The proposed network architecture is divided into: fronthaul network con-necting between the distributed-unit (DU) and the remote-radio-unit (RRU); and midhaul network connecting between the central unit (CU) and the DU. At the midhaul, an aggregated 2.333-Tbit/s transmission is achieved using wavelength division multiplexed (WDM) infrared (IR) based invisible light communication (IVLC). For the link between the RRU and user-equipment (UE), 2.7 Gbit/s white-light visible-light-communication (VLC) transmission is achieved for indoor 1.5 m transmission. It can provide communication and lighting simultaneously. A gateway (GW) is also proposed acting as the interface between the IVLC and VLC transmissions. In the proposed architecture, about 400 VLC end-users can be supported.
20 Gbit/s Tricolor R/G/B Laser Diode based Bi-directional Signal Remodulation Visible Light Communication System
(2018-01-01)
Wei, Liang-Yu
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Hsu, Chin-Wei
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Hsu, Yung
;
Chow, Chi-Wai
;
Yeh, Chien-Hung
We demonstrate a bi-directional signal-remodulated visible-light-communication (VLC) system using tricolor R/G/B laser diodes to produce a 20.231-Gbit/s orthogonal-frequency-division-multiplexed (OFDM) downstream signal and 2-Mbit/s remodulated on-off-keying (OOK) upstream signal.
20.231 Gbit/s tricolor red/green/blue laser diode based bidirectional signal remodulation visible-light communication system
(2018-05-01)
Wei, Liang-Yu
;
Hsu, Chin-Wei
;
Chow, Chi-Wai
;
Yeh, Chien-Hung
;
交大名義發表
We propose and experimentally demonstrate a recorded 1-m bidirectional 20.231-Gbit/s tricolor R/G/B laser diode (LD) based visible-light communication (VLC) system supporting signal remodulation. In the signal remodulation system, an LD source is not needed at the client side. The client reuses the downstream signal sent from the central office (CO) and remodulates it to produce the upstream signal. As the LD sources are located at the CO, the laser wavelength and temperature managements at the cost-sensitive client side are not needed. This is the first demonstration, to our knowledge, of a > 20 Gbit/s data rate tricolor R/G/B VLC signal transmission supporting upstream remodulation. (c) 2018 Chinese Laser Press
40-Gbit/s Visible Light Communication using Polarization-Multiplexed R/G/B Laser Diodes with 2-m Free-Space Transmission
(2019-01-01)
Wei, Liang-Yu
;
Hsu, Chin-Wei
;
Chow, Chi-Wai
;
Yeh, Chien-Hung
;
光電工程學系
We demonstrate a recorded 40.665-Gbit/s visible-light-communication (VLC) system using polarization multiplexed red/green/blue (R/G/B) laser-diodes (LDs) with 2-m free-space transmission. Bit-and-power-loading orthogonal-frequency-division-multiplexed (OFDM) signal is employed.
512-Gbit/s PAM-4 Signals Direct-Detection using Silicon Photonics Receiver with Volterra Equalization
(2018-01-01)
Hsu, Yung
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Chuang, Chun-Yen
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Wei, Liang-Yu
;
Chow, Chi-Wai
;
Wu, Xinru
A 400-Gbit/s Ethernet (GbE) pulse-amplitude-modulation-4 (PAM-4) over 10-km single-mode-fiber (SMF) transmission direct-detected by an integrated silicon-photonics-receiver satisfying the IEEE P802.3bs requirement; and its feasibility to support 512-Gbit/s were illustrated.
Adaptive filtering for white-light LED visible light communication
(2017-01)
Hsu, Chin-Wei
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Chen, Guan-Hong
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Wei, Liang-Yu
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Chow, Chi-Wai
;
Lu, I-Cheng
White-light phosphor-based light-emitting diode (LED) can be used to provide lighting and visible light communication (VLC) simultaneously. However, the long relaxation time of phosphor can reduce the modulation bandwidth and limit the VLC data rate. Recent VLC works focus on improving the LED modulation bandwidths. Here, we propose and demonstrate the use of adaptive Volterra filtering (AVF) to increase the data rate of a white-light LED VLC system. The detailed algorithm and implementation of the AVF for the VLC system have been discussed. Using our proposed electrical frontend circuit and the proposed AVF, a significant data rate enhancement to 700.68 Mbit/s is achieved after 1-m free-space transmission using a single white-light phosphor-based LED. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)
Adaptive filtering for white-light LED visible light communication
(2017-01-01)
Hsu, Chin-Wei
;
Chen, Guan-Hong
;
Wei, Liang-Yu
;
Chow, Chi-Wai
;
Lu, I-Cheng
White-light phosphor-based light-emitting diode (LED) can be used to provide lighting and visible light communication (VLC) simultaneously. However, the long relaxation time of phosphor can reduce the modulation bandwidth and limit the VLC data rate. Recent VLC works focus on improving the LED modulation bandwidths. Here, we propose and demonstrate the use of adaptive Volterra filtering (AVF) to increase the data rate of a white-light LED VLC system. The detailed algorithm and implementation of the AVF for the VLC system have been discussed. Using our proposed electrical frontend circuit and the proposed AVF, a significant data rate enhancement to 700.68 Mbit/s is achieved after 1-m free-space transmission using a single white-light phosphor-based LED. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)
Bi-directional Visible Light Communication Using a Single 682-nm Visible Vertical-Cavity Surface-Emitting Laser (VCSEL) and Signal Remodulation
(2017-01-01)
Wei, Liang-Yu
;
Hsu, Chin-Wei
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Hsu, Yung
;
Yeh, Chien-Hung
;
Chow, Chi-Wai
We demonstrate a bi-directional signal-remodulated visible light communication (VLC), using 8.148-Gbit/s orthogonal-frequency-division-multiplexed (OFDM) downstream and signal remodulated 2-Mbit/s on-off-keying (OOK) upstream, with 3-m free-space transmission distance.
Bidirectional Visible Light Communication System Using a Single VCSEL With Predistortion to Enhance the Upstream Remodulation
(2018-06-01)
Wei, Liang-Yu
;
Chow, Chi-Wai
;
Hsu, Chin-Wei
;
Yeh, Chien-Hung
;
光電工程學系
The demand of higher data rates has made it attractive to consider a low-cost laser diode (LD), such as vertical-cavity-surface-emitting laser (VCSEL) for use in visible light communication (VLC) transmitters (Tx) due to their higher electrical-to-optical modulation bandwidth, beam convergence, and energy efficiency. Many reported LD-based VLC systems only had a solitary downstream transmission. We demonstrate a 3-m bidirectional signal remodulated VCSEL-based VLC system using visible-light modulator to produce the upstream signal. The visible-light external modulator usually has limited modulation bandwidth. By using the predistortion, the upstream remodulated data rate is enhanced by similar to 2.8 times. Hence, the VCSEL-based VLC system with 10.64-Gb/s downstream signal and 5-Mb/s upstream remodulated signal can be achieved. We also analyze via numerical simulations how the predistorted signal can enhance the transmission data rate by mitigating the intersymbol interference introduced by the bandwidth limitation of the upstream modulator.
Digital Signal Processing for Visible Light Communication Applications
(2019-01-01)
Chow, Chi-Wai
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Chen, Guan-Hong
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Peng, Ching-Wei
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Wei, Liang-Yu
;
Yeh, Chien-Hung
We reviewed our resent works using digital-signal-processing (DSP) techniques to improve visible-light-communication (VLC). A rolling-shutter-effect (RSE) light-panel and CMOS image-sensor based VLC and a visible-light-positioning (VLP) system using machine learning are discussed.
Light Encryption Scheme Using Light-Emitting Diode and Camera Image Sensor
(2016-02-01)
Liu, Yang
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Liang, Kevin
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Chen, Hung-Yu
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Wei, Liang-Yu
;
Hsu, Chin-Wei
Visible light communication (VLC) is regarded as relatively secure communication when compared with other wireless communications using radio frequency (RF). However, due to the visual nature, the VLC signals are still subject to eavesdropping when they are emitted by the light source. Here, we propose a light encryption scheme using devices having light-emitting diode (LED) and a camera image sensor, such as a mobile phone. The original visible signal sending from the lamp can be first received by the proposed light encrypter. The information can be encrypted and then emitted. The light encrypter acts as an encryption gateway for signals in optical domain. The rolling shutter effect of the complementary metal-oxide semiconductor (CMOS) camera in the mobile phone can be used. By demodulating the rolling shutter pattern, the data information can be obtained. We also propose and demonstrate using the Otsu thresholding scheme to define the data logic in the rolling shutter pattern. We show that the Otsu scheme is effective for estimating the bit error rate (BER). The optimum number of intervals (segmentations) and the process time of the Otsu method are also studied.
Long distance non-line-of-sight (NLOS) visible light signal detection based on rolling-shutter-patterning of mobile-phone camera
(2017-05-01)
Wang, Wei-Chung
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Chow, Chi-Wai
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Wei, Liang-Yu
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Liu, Yang
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Yeh, Chien-Hung
We propose and demonstrate a long distance non-line-of-sight (NLOS) visible light signal detection based on the rolling shutter patterning using commercial mobile phone camera. By using our improved rolling shutter pattern demodulation algorithm, such as the background compensation (BC) blooming mitigation, extinction-ratio (ER) enhancement and Bradley adaptive thresholding, a 1.5 m NLOS visible signal (at low illumination of 145 lux) can be retrieved. (C) 2017 Optical Society of America
Mult-Gbit/s phosphor-based white-light and blue-filter-free visible light communication and lighting system with practical transmission distance
(2020-03-02)
Wei, Liang-Yu
;
Chow, Chi-Wai
;
Liu, Yang
;
Yeh, Chien-Hung
;
光電工程學系
High speed visible light communication (VLC) is a technology with great potential for future mobile and wireless communication. Here, we report and demonstrate a 2.705 Gbit/s white-light VLC and illumination system supporting indoor transmission distance of 1.5 m, corresponding a illumination of 545 lux. We also study the performance tolerance offset ranges in both x- and y-directions. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Silicon-on-Insulator (SOI) based Polarization-Exchanger using Asymmetric Directional Coupler
(2018-01-01)
Peng, Ching-Wei
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Chang, Yuan-Chia
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Cheng, Ming-Wei
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Hsu, Yung
;
Wei, Liang-Yu
We propose an silicon-on-insulator (SOI) based polarization-exchanger using bi-level-tapers and asymmetric-directional-couplers. Signal from transverse-electric (TE) polarization can be switched to transverse-magnetic (TM) polarization and vice versa. Crosstalk <= -25dB is observed in 40nm wavelength window.
Symmetric > 67 Gbps OFDM-IMDD based WDM access network for mitigating Rayleigh backscattering interference noise
(2020-01-01)
Yeh, Chien-Hung
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Chow, Chi-Wai
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Wei, Liang-Yu
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光電工程學系
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Department of Photonics
In this paper, we propose a symmetric >67 Gbps/lambda wavelength-division-multiplexing (WDM) access network with mitigation of Rayleigh backscattering (RB) interference noise by using the orthogonal frequency division multiplexing (OFDM) modulation and intensity modulation and direct detection (IMDD) method. According to the optimal OFDM bit-loading algorithm design, the fiber chromatic dispersion and RF fading can be improved after a length fiber connection of 20 km long. Moreover, the obtained OFDM modulation rate also can meet the forward error correction (FEC) target.
Tricolor visible-light laser diodes based visible light communication operated at 40.665 Gbit/s and 2 m free-space transmission
(2019-09-02)
Wei, Liang-Yu
;
Chow, Chi-Wai
;
Chen, Guan-Hong
;
Liu, Yang
;
Yeh, Chien-Hung
Visible light communication (VLC) can provide a dedicated, secure, and high data rate wireless transmission link. It has gained considerable attentions recently, and is considered as one of the promising technologies for beyond 5G mobile and wireless communications. In this work, we demonstrate a VLC system with a recorded data rate of 40.665 Gbit/s using tricolor red, green and blue (RGB) laser diodes (LDs) and polarization multiplexing. 2 m free-space transmission distance is achieved. The implementation of bit-loading, power-loading, and polarization multiplexing are discussed. Experimental bit-errorratio (BER) results show that each of the 6 polarization and wavelength de-multiplexed channels can achieve the forward-error-correction (FEC) requirement. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Using a Single VCSEL Source Employing OFDM Downstream Signal and Remodulated OOK Upstream Signal for Bi-directional Visible Light Communications
(2017-11-20)
Yeh, Chien-Hung
;
Wei, Liang-Yu
;
Chow, Chi-Wai
;
光電工程學系
;
光電工程研究所
In this work, we propose and demonstrate for the first time up to our knowledge, using a 682 nm visible vertical-cavity surface-emitting laser (VCSEL) applied in a bi-directional wavelength remodulated VLC system with a free space transmission distance of 3 m. To achieve a high VLC downstream traffic, spectral efficient orthogonal-frequency-division-multiplexing quadrature-amplitude-modulation (OFDM-QAM) with bit and power loading algorithms are applied on the VCSEL in the central office (CO). The OFDM downstream wavelength is remodulated by an acousto-optic modulator (AOM) with OOK modulation to produce the upstream traffic in the client side. Hence, only a single VCSEL laser is needed for the proposed bi-directional VLC system, achieving 10.6 Gbit/s OFDM downstream and 2 Mbit/s remodulated OOK upstream simultaneously. For the proposed system, as a single laser source with wavelength remodulation is used, the laser wavelength and temperature managements at the client side are not needed; and the whole system could be cost effective and energy efficient.
Visible Light Communication Using Advertisement-Light-Board and Rolling-Shutter-Effect based CMOS Mobile-Phone Camera
(2018-01-01)
Shiu, Ruei-Jie
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Liu, Yen-Chun
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Chow, Chi-Wai
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Wei, Liang-Yu
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Hsu, Yung
We demonstrate a visible-light-communication (VLC) system using advertisement-light-board and CMOS-camera. Experiments at wireless transmission distances of 50cm, 100cm and 150cm are performed, and at data-rate of 720bit s, satisfying the forward-error-correction (FEC) threshold.
Visible light communications for the implementation of internet-of-things
(2016-06-01)
Chen, Chia-Wei
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Wang, Wei-Chung
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Wu, Jhao-Ting
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Chen, Hung-Yu
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Liang, Kevin
It is predicted that the number of internet-of-things (IoT) devices will be >28 billion in 2020. Due to the shortage of the conventional radio-frequency spectrum, using visible light communication (VLC) for IoT can be promising. IoT networks may only require very low-data rate communication for transmitting sensing or identity information. The implementation of a VLC link on existing computer communication standards and interfaces is important. Among the standards, universal asynchronous receiver/transmitter (UART) is very popular. We propose and demonstrate a VLC-over-UART system. Bit error rate analysis is performed. Different components and modules used in the proposed VLC-over-UART system are discussed. Then, we also demonstrate a real-time simultaneous temperature, humidity, and illuminance monitoring using the proposed VLC link. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)