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- 摘要
- 关键词
- 实验方案
- 产品
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[IEEE 2019 IEEE Energy Conversion Congress and Exposition (ECCE) - Baltimore, MD, USA (2019.9.29-2019.10.3)] 2019 IEEE Energy Conversion Congress and Exposition (ECCE) - An Energy Efficient Li-Fi Transmitter with Single Inductor Multiple Output LED Driver
摘要： High-Efficiency Light-Fidelity (Li-Fi) transmitter for simultaneous illumination and Visible Light Communications (VLC) using LED lighting is presented in this work. The proposed transmitter is based on Single Inductor Multiple Output (SIMO) buck converter with two independently controllable outputs or channels, namely lighting channel and communications channel for enabling flicker free illumination without affecting high-speed modulation of LEDs. By this approach, power converter switching frequency is decoupled from modulation frequency of LEDs, thereby optimizing SIMO converter switching frequency for efficiency and the VLC modulator frequency for high speed data transfers. GaN devices are used to realize VLC modulator for high speed modulation to further enhance the efficiency. Light output with high Color Rendering Index (CRI) is achieved by controlling white LEDs as primary illumination source at lighting channel and red color LEDs at communication channel. Simulations and experimental results to validate the proposed transmitter are presented.
关键词： Single Inductor Multiple Output Converters,Color Rendering Index(CRI),Light-Fidelity(Li-Fi),High Brightness Light Emitting Diodes(HB-LED),Visible Light Communications (VLC),IoT (Internet of Things)
更新于2025-09-11 14:15:04
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[IEEE 2018 IEEE 2nd International Conference on Circuits, System and Simulation (ICCSS) - Guangzhou, China (2018.7.14-2018.7.16)] 2018 IEEE 2nd International Conference on Circuits, System and Simulation (ICCSS) - Application of an Infinite Gain Multiple Feedback Filter in VLC Link Range Extension
摘要： This paper presents a visible light communication (VLC) link range extension, achieved by establishing a VLC system using simple, low-cost, and reliable electronic circuitry, and employing a design of a highly resonant frequency selective active band pass filter (infinite gain multiple feedback filter) at the receiver section of the system. The filter was designed for a specific center (resonant) frequency with high Quality factor and gain. An outline of the relationship between Signal-to-Noise ratio (SNR) and transmission distance for three different center frequencies was presented. Results show that by utilizing an IGMF filter at the receiver, a signal-to- noise ratio above 10dB at a distance beyond 1.5 meters can be achieved without any form of lensing at either the transmitter or receiver.
关键词： Signal-to-Noise Ratio (SNR),Infinite Gain Multiple Feedback (IGMF),Visible Light Communications (VLC),LED,Trans-Impedance Amplifier (TIA)
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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Indoor visible light communications: performance evaluation and optimization
摘要： For indoor visible light communication (VLC), much work has been done when the noise is independent of the input signal. However, less effort is made when the VLC system suffers from the input-dependent noise. Considering the input-dependent noise, this paper focuses on the performance analysis and optimization for indoor VLC system. The Lambertian emission-based channel model and on-off keying modulation are employed. According to the system model, the bit error rate (BER) with a closed-form expression is derived. To enhance the system performance, an optimization problem that minimizes the BER by tilting the receiver plane is formulated. By solving the problem, the optimal tilting angle of the receiver is obtained. Simulation results verify the derived expression of BER. It is also shown that the BER is strongly affected by the input-dependent noise. Moreover, the optimal tilting angles for the receiver at any position are obtained, which can provide some insights for practical system design.
关键词： BER,Tilting receiver plane,Input-dependent noise,Visible light communications
更新于2025-09-10 09:29:36
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - High-Bandwidth Organic Light Emitting Diodes for Ultra-Low Cost Visible Light Communication Links
摘要： Visible light communications (VLC) have attracted considerable interest in recent years due to an increasing need for data communication links in home and enterprise environments. Organic light-emitting diodes (OLEDs) are widely used in display applications owing to their high brightness, high quality colour-rending capability and low cost. As a result, they are attractive candidates for the implementation of ultra-low cost visible light optical links in free-space and guided-wave communications. However, OLEDs need to exhibit a bandwidth of at least ~MHz to be able to support the modest data rates (~Mbps) required in these applications. Although fluorescent OLEDs typically exhibit shorter photon lifetimes than inorganic LEDs, the bandwidth performance of the large size OLEDs used in display applications are limited by their electrical characteristics. In this work, we present a detailed physical simulation that describes well the performance of fast OLED devices that exhibit significant -3 dB bandwidths (f3dB) of 44 MHz obtained for a 0.12 mm2 device. It is demonstrated that the reduction of the device size results in a significant bandwidth improvement due primarily to a reduction in parasitic capacitance of the devices, though this is counteracted by carrier dynamic effects. The model provides an insight into the basic physical properties of the OLED and may be used for optimisation of future generations of OLED devices.
关键词： simulation,visible light communications,modelling,OLED
更新于2025-09-10 09:29:36
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Indoor visible light positioning combined with ellipse-based ACO-OFDM
摘要： Visible light communications have recently gained increasing attention as it is appealing for a wide range of applications such as indoor positioning. However, the light-emitting diode-based indoor positioning systems suffer from multipath distortion inside a room, leading to high positioning error. In order to mitigate the effect of multipath distortion of the optical channel, an indoor visible light positioning algorithm combined with ellipse-based asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) is proposed in this study, wherein the real-valued output of orthogonal frequency division multiplexing is modulated onto an ellipse, and only the imaginary value from the complex point on the ellipse is transmitted. Moreover, a received-signal-strength technique is used to determine the location of the receiver, and the Trust- region technique is employed to realise the 3D positioning. Simulation results demonstrate that this proposed algorithm can achieve high positioning accuracy, and the impact of different system parameters on the positioning accuracy is further investigated compared with the systems based on ACO-OFDM.
关键词： indoor positioning,ellipse-based modulation,Trust-region technique,ACO-OFDM,visible light communications,multipath distortion,RSS technique
更新于2025-09-10 09:29:36
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Deployment Issues and Performance Study in a Relay-Assisted Indoor Visible Light Communication System
摘要： This paper investigates the deployment issues and analyzes the performance of a relay-assisted indoor visible light communications (VLC) system with dc-biased optical orthogonal frequency division modulation (DCO-OFDM). The study considers two light sources in an office environment. One light source works as the information source and is located at the ceiling while the other one works as the relay terminal, which usually is a desk light or a floor light. We analyze the general blockage in a room, discuss the path loss of the VLC channel, and compare received signal power from a line of sight (LOS) link and a non-LOS link. The constraints on the relay height in order to achieve LOS connection are investigated. Simplified optimal power allocation under illumination and blockage constraints is proposed. Bit error rate performance is analyzed and the required signal power is derived for the relay-assisted DCO-OFDM VLC system. The study shows that in a relay-assisted VLC system, the blockage of source to destination link has trivial influence on the overall system performance if relays are properly deployed.
关键词： indoor,visible light communications (VLC),dc-biased optical orthogonal frequency division modulation (DCO-OFDM),relay,Channel model,power allocation
更新于2025-09-09 09:28:46
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Visible Light Communications (Theory and Applications) || VLC for Indoor Positioning
摘要： As the world has become an increasingly connected ecosystem, data demand has continually pushed the limits of our wireless networks. Each generation of wireless technology has added extensive wireless capacity; however, novel use cases and technological adoption have continually raised the demand at rates previously unseen. This trend continues today as massive data downloads, video streaming, augmented reality, and the Internet of Things push the limits of 4G networks. Furthermore, increasing application complexity and demand per device is paired with an increasing number and density of wireless devices. Hence, the wireless communications industry is challenged to meet an extreme growth in data traffic in the coming years—a demand growth that is unlikely to be met with iterative modifications to the current infrastructure. With this in mind, the world mobile and wireless infrastructure community is looking toward the 5th generation of mobile telecommunications, or 5G, with the expectation that new technologies will be adopted which drastically alter the conventional view of wireless networks.
关键词： Visible Light Communications,Software Defined VLC,RF/VLC HetNets,VLC,5G
更新于2025-09-09 09:28:46
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Visible Light Communications (Theory and Applications) || Lighting and Communications: Devices and Systems
摘要： An important step in the design of a visible light communications (VLC) system is to comprehend the limitations arising from the optical wireless channel. Accurate channel characterization is an important prerequisite to set the system parameters appropriately in order to establish a high-quality link since it permits better exploitation of the available energy and spectral resources in view of optimizing the system design. An accurate channel model is also necessary to precisely predict the performance of VLC systems. In this chapter, we address channel modeling for VLC systems mainly focusing on indoor systems. We introduce different sources of impairment in VLC systems arising from beam propagation or transmitter (Tx)/receiver (Rx) devices. Indeed, the latter could be attributed to the “global channel” comprising the blocks between the signal Tx and signal detection at the Rx. After this introduction, we give an overview of different propagation modes in Section 3.2. In addition, we explain methods for numerical channel simulation. Analytical channel modeling for the cases of single- and multiple-source systems is presented in Section 3.3. Then, in Section 3.4, we outline the limitations arising from the aggregate channel while focusing on the problem of intersymbol interference (ISI) and how it affects the link performance particularly in the absence of a line of sight (LOS). This could be due to multipath-induced channel time dispersion, that is, multiple reflections from people and objects within an indoor environment, the lack of sufficient bandwidth of the transmitting device, most commonly a light-emitting diode (LED), the photodetector (PD), and the cabling used for lighting installations. Limitations due to the LED nonlinear characteristics could also be considered as an impairment of the global channel, which is the subject of Section 3.5 where channel distortion modeling is investigated. Finally, channel modeling for multiple-input multiple-output (MIMO) VLC systems will be presented next in Section 3.6.
关键词： Channel Modeling,Intersymbol Interference,Multiple-Input Multiple-Output,Optical Wireless Channel,Visible Light Communications
更新于2025-09-09 09:28:46
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Multiple Access Design for Ultra-Dense VLC Networks: Orthogonal v.s. Non-Orthogonal
摘要： Small cell aided ultra-dense networks (UDN) constitute an efficient solution to the ever-increasing thirst for more data. Thanks to the vast untapped high-frequency spectrum of visible light, visible light communications (VLC) is a natural candidate for UDN. In this paper, layered asymmetrically clipped optical OFDM (LACO-OFDM) aided ultra-dense VLC (UD-VLC) is investigated in terms of its user-association, multiple access (MA) and resource allocation. To handle the severe inter-cell interference (ICI) amongst the densely-deployed access points (AP), we propose a novel overlapped clustering technique relying on a hybrid non-orthogonal MA (NOMA) and orthogonal MA (OMA) scheme for enhancing the performance, with the aid of our dynamic resource allocation conceived. Our simulations show that the proposed LACO-OFDM aided UD-VLC using our hybrid MA scheme is more robust against the ICI, at a price of modestly decreasing the sum-throughput.
关键词： visible light communications (VLC),resource allocation,non-orthogonal multiple access (NOMA),Ultra-dense network (UDN),multiple access (MA)
更新于2025-09-09 09:28:46