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Improved Joint Generalized Spatial Modulations for MIMO-VLC Systems
摘要： In this letter, we propose the computationally efficient constellation design algorithms for single-mode and dual-mode joint generalized spatial modulations (JGSMs) to improve the symbol error rate (SER) performance over highly correlated indoor visible light communication channels. Our simulation results show that the proposed joint and improved dual-mode JGSMs can offer a better SER performance than the proposed single-mode JGSM (SM-JGSM) and the conventional SM-JGSM, which are validated through the analytical bounds.
关键词： Correlated channels,multiple-input multiple-output (MIMO),visible light communication (VLC),joint generalized spatial modulation (JGSM)
更新于2025-09-10 09:29:36
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Design of Polar Codes for Run-Length Limited Codes in Visible Light Communications
摘要： In this paper, we proposed a design of polar codes for run-length limited (RLL) codes by using frozen bit indexes in visible light communications. Thanks to generator matrix structure and channel selection procedures of polar codes, pre-determined frozen indexes are defined to produce different number of segments. The indexes are used to make different a priori probabilities in RLL decoding to improve bit error rate (BER) performance. Simulation results show that the proposed algorithm provides better BERs than referenced schemes.
关键词： visible light communications (VLC),run-length limited (RLL) codes,polar codes
更新于2025-09-10 09:29:36
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[IEEE 2017 IEEE International Conference on Computational Intelligence and Computing Research (ICCIC) - Coimbatore, India (2017.12.14-2017.12.16)] 2017 IEEE International Conference on Computational Intelligence and Computing Research (ICCIC) - Multiuser Visible Light Communication System For Reliable Wireless Communication
摘要： Visible Light Communication (VLC) is evolving likewise a guaranteeing act on give pervasive remote association. In this paper, we study an indoor multiuser Visible Light Communication framework can substantially increase the achievable bit rate of Adaptively Modulated Optical Orthogonal Frequency-Division Multiplexing (AMO-OFDM) system and has the ability to maximise data throughput by adjusting the number of bits per subcarrier based on the set of subcarrier's channel Gain to Noise Ratio (GNR). For each subcarrier resolved alongside OFDM, those comparing precoding grids will be in the recurrence area to eradicate multiuser viewed as obstruction. VLC is one of the promising candidates because of its features of non-licensed channels, high bandwidth and low power consumption. As a visible light source can be used both for illumination and communication, therefore, it saves the extra power that is required in RF communication. The revolution in the field of solid state lighting leads to the replacement of florescent lamps by Light Emitting Diodes (LEDs) which further motivates the usage of VLC.The modulation bandwidth of white emanation is about ～2MHz.
关键词： VLC (Visible Light Communication),Multiple transmitter and receiver links,MIMO (Multiple Input Multiple Output),OFDM (Orthogonal Frequency Division Multiplexing),MMSE (Minimum Mean-Squared Error),Precoding
更新于2025-09-10 09:29:36
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Fabrication of CdS hierarchical multi-cavity hollow particles for efficient visible light CO <sub/>2</sub> reduction
摘要： Designing advanced structures for semiconductor photocatalysts is an effective approach to enhance their performance. However, it is not easy to fabricate functional photocatalytic materials with complex nano-architectures. Here we have developed a sequential solution growth, sulfidation and cation-exchange strategy to fabricate CdS hierarchical multi-cavity hollow particles (HMCHPs). This strategy starts with the growth of Zn-based zeolitic imidazolate framework (ZIF-8) onto cobalt glycerate (Co-G) solid spheres. Sulfidation of the obtained Co-G@ZIF-8 composite particles leads to the formation of CoSx@ZnS HMCHPs, which are converted into CdS HMCHPs via a cation-exchange reaction. Owing to the favourable properties of the well-defined hierarchical hollow structure, the CdS HMCHPs exhibit enhanced activity for photocatalytic CO2 reduction compared with other CdS photocatalysts with solid and common hollow structures. The performance of CdS HMCHPs can be further promoted by loading of Au to reach a CO generation rate of 3758 μmol h?1 g?1 under visible light irradiation.
关键词： Au loading,hierarchical multi-cavity hollow particles,CdS,photocatalytic CO2 reduction,visible light
更新于2025-09-10 09:29:36
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Evaluating the risk of eavesdropping a visible light communication channel
摘要： Visible light communication (VLC) technologies are becoming a method to communicate with a wide range of devices. One of VLC's biggest proposed advantages is the inherent security that this technology provides. The concept of securing on VLC is based on its indoor use since optical radiation is confined by walls. However, doors and windows are usually present in any inhabited structure through which the optical signal can leak and be detected by external devices. In this study, the signal leaked through such a window and the risk of eavesdropping the VLC-based channel may have is studied. In this way, a risk evaluation parameter, which includes different variables, is proposed and analysed.
关键词： Visible light communication,eavesdropping,security,risk evaluation,VLC
更新于2025-09-10 09:29:36
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Synthesis Optimization and Characterization of Visible-light Responsive Ce-doped Titanate Nanotubes for Enhanced Degradation of Polluting Dyes in Aqueous Environment
摘要： For the decomposition organic substrates in the reaction container, we developed Ce-doped titanate nanotubes as visible light responsive photo catalyst. Anatase titania and titanate nanotubes were prepared using the sol-gel method and hydrothermal method. The photoactivity of Ce-doped titanate nanotubes under visible light were dramatically improved than anatase titania and titanate nanotubes. All titania and titanate nanotubes were characterized using X-ray diffraction, field emission scanning electron microscopy, inductively coupled plasma-atomic emission spectroscopy and UV-Vis absorption spectroscopy. Their’s photocatalytic activities were investigated by the degradation rate of methylene blue solution under UV and visible light condition. The crystalinity of the titanate nanotubes were increased by Ce-doping compared with that of pure titania nanotube. In addition, the UV-Vis absorption ranges of Ce-doped anatase titania and Ce-doped titania nanotube were red shifted by Ce-doping. These morphology changes to nanotubes with Ce-doping will be very useful for practical application for decomposing color dyes included amino group in the wasted water.
关键词： visible light photoactivity,titanate nanotubes,Ce doping,photocatalyst,TiO2
更新于2025-09-10 09:29:36
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Synthesis and characterization of CuZnO@GO nanocomposites and their enhanced antibacterial activity with visible light
摘要： Copper and zinc composite oxide (CuZnO) was synthesized successfully via a sol–gel method and modi?ed by silane coupling agent to prepare CuZnO@graphene oxide (CuZnO@GO) nanocomposites, with CuZnO nanoparticles (NPs) distributed on the GO nanosheets. The structural properties of prepared CuZnO@GO nanocomposites were studied by FT-IR and XRD techniques. SEM and TEM analysis showed the spherical morphology of CuZnO NPs with a diameter of 20–40 nm. The optical properties of synthesized products were estimated through UV–Vis DRS and PL spectroscopy, which suggested that CuZnO@GO nanocomposites had a widened absorption range from UV to visible region and a lower photogenerated carrier recombination rate than that of pure CuZnO NPs. The antibacterial mechanism of CuZnO@GO nanocomposites was investigated using gram-negative bacteria Escherichia coli and gram-positive bacteria Staphylococcus aureus as two model microorganisms. The antibacterial properties of CuZnO@GO nanocomposites on mixed bacteria were researched in the cooling water system. The results showed that when adding CuZnO@GO nanocomposites to E. coli or S. aureus suspension, the protein leakage after 20 h was 10.5 times or 8.3 times higher than that in the blank experiment. Furthermore, the antibacterial activity of CuZnO@GO nanocomposites in presence of visible light was found to be signi?cantly enhanced as compared with control. Under visible light irradiation, the antibacterial rate of CuZnO@GO nanocomposites in circulating cooling water reached 99.09% when the mass fraction of GO was 17.5%, and more than 90% of bacteria were inactivated by 100 mg L?1 CuZnO@GO nanocomposites in 60 min after four recycled runs.
关键词： Water treatment,CuZnO@GO nanocomposites,Visible light,Photocatalytic antibacterial activity,Antibacterial mechanism
更新于2025-09-10 09:29:36
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[IEEE 2018 10th International Conference on Information Technology and Electrical Engineering (ICITEE) - Bali, Indonesia (2018.7.24-2018.7.26)] 2018 10th International Conference on Information Technology and Electrical Engineering (ICITEE) - A Circuit for Robust Visible Light Communication Systems in Indoor Environment
摘要： In the recent decades, Visible light communication (VLC) becomes the favorite research topic in the world. VLC has been successfully applied to the outdoor or indoor area though not yet en masse. The VLC transceivers operating in typical indoor environments are subject to intense ambient light, emanating from both natural and artificial sources. The primary sources of ambient light as mentioned before are the background light comes from sunlight, DC light sources (LED bulb & flashlight), incandescent and fluorescent lamps. These signal must be filtered-out because it will make the received signal distortion. Previous research about low-cost Analog Front-End (AFE) circuit has been carried out on the simulation only. This research is trying to test the designed AFE receiver circuit on the laboratory. Moreover, we add the several analog blocks to be involved. The test data obtained; the designed circuit able to compensate the optical noise. It makes VLC system has robustness ability from other lights in the indoor environment.
关键词： Indoor Environment,Visible light communication,Robust VLC,Analog Front-End
更新于2025-09-10 09:29:36
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Outage and error analysis of three hop hybrid VLC/FSO/VLC-based relayed optical wireless communication system
摘要： In this paper, we consider a three hop hybrid visible light communication/free space optical/visible light communication (VLC/FSO/VLC) system in which the information is transmitted from a room inside the building on a VLC link toward the decode and forward (DF) relay attached to that building. The relay maps the incoming signal on the FSO link and forwards it to the other DF relay attached to the second building, which further passes it down to the user inside the room onto the VLC downlink. The VLC and FSO links follow the Lambertian emission model and Gamma-Gamma fading statistics, respectively, under the impact of atmospheric turbulence, pointing errors, semiangle, and field of view of the detector. The performance of the three hop hybrid system is derived in terms of the closed-form expression for the outage probability. The error performance is analyzed in terms of average symbol error probability of the considered hybrid system. Furthermore, an expression for asymptotic outage probability of the system is derived to investigate the behavior of the system at high signal-to-noise ratio (SNR) regimes. The impact of variation in the parameters on the hybrid VLC/FSO//VLC communication system performance is illustrated by the numerical plots.
关键词： free space optical,relayed optical wireless communication,outage probability,average symbol error probability,visible light communication
更新于2025-09-10 09:29:36
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Construction of 2D-2D TiO2 nanosheet/layered WS2 heterojunctions with enhanced visible-light-responsive photocatalytic activity
摘要： Constructing nanocomposites that combine the advantages of composite materials, nanomaterials, and interfaces has been regarded as an important strategy to improve the photocatalytic activity of TiO2. In this study, 2D-2D TiO2 nanosheet/layered WS2 (TNS/WS2) heterojunctions were prepared via a hydrothermal method. The structure and morphology of the photocatalysts were systematically characterized. Layered WS2 (~4 layers) was wrapped on the surface of TiO2 nanosheets with a plate-to-plate stacked structure and connected with each other by W=O bonds. The as-prepared TNS/WS2 heterojunctions showed higher photocatalytic activity for the degradation of RhB under visible-light irradiation, than pristine TiO2 nanosheets and layered WS2. The improvement of photocatalytic activity was primarily attributed to enhanced charge separation efficiency, which originated from the perfect 2D-2D nanointerfaces and intimate interfacial contacts between TiO2 nanosheets and layered WS2. Based on experimental results, a double-transfer photocatalytic mechanism for the TNS/WS2 heterojunctions was proposed and discussed. This work provides new insights for synthesizing highly efficient and environmentally stable photocatalysts by engineering the surface heterojunctions.
关键词： WS2,Nanosheet,TiO2,Heterojunction,Visible-light responsive,Photocatalysis
更新于2025-09-10 09:29:36