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2.333-Tbit/s bi-directional optical mobile networks using optical wireless communication (OWC)
(2020-11-15)
Wei, Liang-Yu
;
Chen, Shu-, I
;
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.
Visible light positioning (VLP) system using low-cost organic photovoltaic cell (OPVC) for low illumination environments
(2020-08-31)
Hong, Chong-You
;
Wu, Yu-Chun
;
Lin, Yu-Hsiang
;
Liu, Yang
;
Chow, Chi-Wai
We propose and demonstrate a received-signal-strength (RSS) based visible light positioning (VLP) system using a low-cost organic photovoltaic cell (OPVC) receiver (Rx). The OPVC is a passive device without the need of external power supply. It could detect VLC signal and harvest energy. Our developed OPVC has a high power conversion efficiency (PCE) of 9.8%. The VLP system can be operated at a low illumination of 130 lux. The regression machine learning (MIL) algorithm is used to enhance the positioning accuracy. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Analysis of Non-Hermitian symmetry (NHS) IFFT/FFT size efficient OFDM for multiple-client non-orthogonal multiple access (NOMA) visible light communication (VLC) system
(2020-10-01)
Adnan, Assaidah
;
Liu, Yang
;
Chow, Chi-Wai
;
Yeh, Chien-Hung
;
交大名義發表
Orthogonal-frequency-division-multiplexing (OFDM) format is widely deployed in visible-light-communication (VLC) systems due to its high spectral efficiency. To produce real-valued OFDM signal for VLC, Hermitian-symmetry (HS) is needed during the inverse-fast-Fourier-transform (IFFT) encoding process. However the HS requirement doubles the IFFT/FFT size and increase the encoding complexity. Non-Hermitian symmetry (NHS)-OFDM schemes are proposed, but they have different limitations. In this work, we propose and investigate a non-orthogonal multiple access (NOMA) VLC network serving 2, 3 or 4 clients simultaneously using NHS-OFDM IFFT/FFT size efficient (SE) OFDM format. Numerical analysis of signal amplitude effect to the bit-error-ratio (BER) performance for different users are performed, showing that the BER < 7% forward-error-correction (FEC) limit can be achieved as long as the required signal amplitude ratio of each user is fulfilled. We also compare the proposed system with a typical example of HS-OFDM modulation, i.e. direct-current optical (DCO)-OFDM NOMA-VLC system.
Digital Signal Processing for Visible Light Communication Applications
(2019-01-01)
Chow, Chi-Wai
;
Chen, Guan-Hong
;
Peng, Ching-Wei
;
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.
Angle-of-Arrival (AOA) Visible Light Positioning (VLP) System Using Solar Cells With Third-Order Regression and Ridge Regression Algorithms
(2020-06-01)
Hong, Chong-You
;
Wu, Yu-Chun
;
Liu, Yang
;
Chow, Chi-Wai
;
Yeh, Chien-Hung
We put forward and demonstrate a angle-of-arrival (AOA) based visible-light-positioning (VLP) system using quadrant-solar-cell (QSC) and third-order ridge regression machine learning (RRML) to improve the positioning accuracy.
Demonstration of Non-Hermitian Symmetry (NHS) IFFT/FFT Size Efficient OFDM Non-Orthogonal Multiple Access (NOMA) for Visible Light Communication
(2020-06-01)
Assaidah, Assaidah
;
Liu, Yang
;
Chow, Chi-Wai
;
Yeh, Ching-Hua
;
交大名義發表
We propose and experimentally demonstrate a non-orthogonal multiple access (NOMA) visible light communication (VLC) system using non-Hermitian symmetry (NHS) inverse-fast-Fourier-transform (IFFT)/FFT size efficient (SE) orthogonal frequency division multiplexing (OFDM). Fix power allocation and successive interference cancellation (SIC) algorithms are realized. The power ratio between different users, transmission distance, network cell coverage are investigated. The proposed scheme is also compared with the HS based direct-current optical (DCO)-OFDM NOMA-VLC system.
Activity and Metabolic Versatility of Complete Ammonia Oxidizers in Full-Scale Wastewater Treatment Systems
(2020-03-01)
Yang, Yuchun
;
Daims, Holger
;
Liu, Yang
;
Herbold, Craig W.
;
Pjevac, Petra
The recent discovery of complete ammonia oxidizers (comammox) contradicts the paradigm that chemolithoautotrophic nitrification is always catalyzed by two different microorganisms. However, our knowledge of the survival strategies of comammox in complex ecosystems, such as full-scale wastewater treatment plants (WWTPs), remains limited. Analyses of genomes and in situ transcriptomes of four comammox organisms from two full-scale WWTPs revealed that comammox were active and showed a surprisingly high metabolic versatility. A gene cluster for the utilization of urea and a gene encoding cyanase suggest that comammox may use diverse organic nitrogen compounds in addition to free ammonia as the substrates. The comammox organisms also encoded the genomic potential for multiple alternative energy metabolisms, including respiration with hydrogen, formate, and sulfite as electron donors. Pathways for the biosynthesis and degradation of polyphosphate, glycogen, and polyhydroxyalkanoates as intracellular storage compounds likely help comammox survive unfavorable conditions and facilitate switches between lifestyles in fluctuating environments. One of the comammox strains acquired from the anaerobic tank encoded and transcribed genes involved in homoacetate fermentation or in the utilization of exogenous acetate, both pathways being unexpected in a nitrifying bacterium. Surprisingly, this strain also encoded a respiratory nitrate reductase which has not yet been found in any other Nitrospira genome and might confer a selective advantage to this strain over other Nitrospira strains in anoxic conditions. IMPORTANCE The discovery of comammox in the genus Nitrospira changes our perception of nitrification. However, genomes of comammox organisms have not been acquired from full-scale WWTPs, and very little is known about their survival strategies and potential metabolisms in complex wastewater treatment systems. Here, four comammox metagenome-assembled genomes and metatranscriptomic data sets were retrieved from two full-scale WWTPs. Their impressive and-among nitrifiers-unsurpassed ecophysiological versatility could make comammox Nitrospira an interesting target for optimizing nitrification in current and future bioreactor configurations.
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
CMOS camera based visible light communication (VLC) using grayscale value distribution and machine learning algorithm
(2020-01-20)
Hsu, Ke-Ling
;
Wu, Yu-Chun
;
Chuang, Yu-Cheng
;
Chow, Chi-Wai
;
Liu, Yang
We demonstrate a visible light communication (VLC) system using light emitting diode (LED) backlight display panel and mobile-phone complementary-metal-oxide-semiconductor (CMOS) camera. The panel is primarily used for displaying advertisements. By modulating its backlight, dynamic contents (i.e. secondary information) can be transmitted wirelessly to users based on rolling shutter effect (RSE) of the CMOS camera. As different display content will be displayed on the panel, the VLC performance is significantly limited if the noise-ratio (NR) is too high. Here, we propose and demonstrate a CMOS RSE pattern demodulation scheme using grayscale value distribution (GVD) and machine learning algorithm (MLA) to significantly enhance the demodulation. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Modal-based ground motion selection procedure for nonlinear response time history analysis of high-rise buildings
(1970-01-01)
Liu, Yang
;
Kuang, J. S.
;
Yuen, Terry Y. P.
;
土木工程學系
;
Department of Civil Engineering
The selection of representative input ground motions (IGMs) is important for a proper nonlinear response time history analysis (NLRHA) of modern structures. The prevailing IGM selection procedure requires that the response spectra of selected ground motions are matched with the code-specified design spectra, while the effect of the frequency contents combination in the time domain on the multimode interactions is not considered. Ignoring the effect of the frequency contents combination in the time domain of IGMs may cause significant variations in the analysis results for selected IGMs, although they are matched to the same design spectrum. In this paper, a modal-based ground motion selection (MGMS) procedure is proposed as a supplement to spectrum matching-based IGM selection procedures for selecting proper IGMs that can sufficiently induce the multimode interactions. In the proposed procedure, three equivalent single-degree-of-freedom (ESDOF) systems are developed by pushover analysis. NLRHA is then conducted for these ESDOF systems with a set of 20 seed IGMs chosen by the spectrum-matching-based selection procedure. Finally, seven IGMs are selected from the seed IGMs for NLRHA in the full structural model. To verify MGMS, seismic demands of high-rise buildings were computed by NLRHA with seven MGMS-selected IGMs, seven IGMs with closest spectrum matching, and groups of seven randomly selected IGMs derived from three different sets of 20 seed IGMs. The computed seismic demands with MGMS-IGMs show very good agreement with the mean demands determined using the whole set of seed IGMs, while the deviation is much lesser compared with those groups of randomly selected IGMs.

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