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[IEEE 2018 International Conference on Advanced Technologies for Communications (ATC) - Ho Chi Minh City, Vietnam (2018.10.18-2018.10.20)] 2018 International Conference on Advanced Technologies for Communications (ATC) - Keynote talk #2: Visible light communications for 5G-and-beyond wireless telecommunications networks
摘要： Artificial general lighting sources are currently evolving through the traditional fluorescent and incandescent sources to the modern energy saving light bulbs and now white light emitting diodes (LEDs). This trend has been spurred on through global awareness of the necessity for reducing the size of our carbon footprint. The introduction of solid state LED lighting has attracted the attention of communications engineer's worldwide, enabling the achievement of the dual functionality of room illumination whilst simultaneously transmitting wireless data via visible light communication (VLC), or Light Fidelity (LiFi), in optical spectrum regime. Although the existing wireless networks are primely dominated by radio-based technology, the emerging VLC will play increasingly important role in future wireless telecommunications landscape. It is anticipated that both spectrum regimes, radio and optical, will eventually contribute equally for the next network generation, especially in nanocell and picocell network structures. This talk will outline the growth of optical wireless communications including VLC, and present the challenges and roadmap of the technology for the future generation of wireless networks.
关键词： Visible Light Communications,Networks,LED,LiFi
更新于2025-09-23 15:23:52
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[IEEE 2017 International Conference on Transforming Engineering Education (ICTEE) - Pune, India (2017.12.13-2017.12.16)] 2017 International Conference on Transforming Engineering Education (ICTEE) - A Performance Analysis of “Light Fidelity” and “Internet of Things” & It's Application
摘要： In today's world, various diseases are increasing, with this a doctor's ability to treat such large number of people deteriorates and also the task to monitor them regularly is painstaking. However we can overcome this problem to a certain extend with the help of newly emerged technology of LIFI and IOT. LIFI or Light Fidelity invented by Prof. Harald Hass of University of Edinburgh and IOT proposed by Kevin Ashton, provide us with one such technology using which a doctor can keep record of his/her patient from anywhere across the world. Since doctor has to stay updated with his patient's condition, we need a noninterfering connectivity which is possible by LIFI and this huge data of patient can be recorded and stored using cloud computing IOT. Once the doctor receives the data, he can analyze them and provide appropriate feedback to the person (nurse) who is currently operating the patient.
关键词： Internet of Things (IOT),Light Fidelity (LIFI)
更新于2025-09-23 15:22:29
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Hybrid DCO-OFDM, ACO-OFDM and PAM-DMT for Dimmable LiFi
摘要： This paper proposes a hybrid orthogonal frequency division multiplexing (OFDM) modulation termed as hybrid DC-biased asymmetrically-clipped pulse-amplitude-modulated OFDM (HDAP-OFDM) for providing power efficient communication and dimming control for light fidelity (LiFi) schemes. The proposed HDAP-OFDM is a combination of three OFDM formats: DC-biased optical OFDM (DCO-OFDM), asymmetrically clipped optical OFDM (ACO-OFDM) and pulse amplitude modulated discrete multitone (PAM-DMT). In HDAP-OFDM, the lower-index subcarriers carry DCO-OFDM, while the remaining higher subcarriers carry ACO-OFDM on the odd-index subcarriers and PAM-DMT on the even-index subcarriers. Mathematical analysis shows that the required DC bias for HDAP-OFDM is a function of the required dimming levels and the root mean square of the three of its components. Furthermore, an algorithm is presented to simulate the dimming control of HDAP-OFDM. Simulations results indicate that by adjusting the proportion of subcarriers for the three OFDM/DMT elements, HDAP-OFDM can have a wide dimming range, a low peak to average power ratio, and high power efficiency. Results also show that at a bit error rate of 10-3 and a dimming range of 3% to 97%, HDAP-OFDM exhibits 8 dB more optical and electrical power efficiency than existing asymmetrical hybrid optical OFDM.
关键词： HDAP-OFDM,optical wireless communication,DC bias,OFDM,dimming,LiFi
更新于2025-09-23 15:21:21
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[IEEE 2018 IEEE Photonics Conference (IPC) - Reston, VA, USA (2018.9.30-2018.10.4)] 2018 IEEE Photonics Conference (IPC) - Experimental Demonstration of User Allocation in a Subcarrier Multiplexing-Based Multiuser LiFi System
摘要： We want to allocate the users to the optimal subcarriers in visible light communication. Allocation algorithms adapted from fiber-optic and implemented in an experimental setup attain a deviation from the bit rate target inferior to 5 percent for 11 users.
关键词： subcarrier multiplexing,multiuser,Indoor network,multiband CAP,LiFi,visible light communication
更新于2025-09-23 15:21:01
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Simultaneous Data Transmission using Multilevel LED in Hybrid OCC/LiFi System: Concept and Demonstration
摘要： In this letter, a hybrid-encoding scheme is developed for an integrated optical camera communication (OCC)/light-fidelity (LiFi) system. A single multilevel light-emitting diode (LED) is used for transmitting both OCC and LiFi data. Two data streams are transmitted, where each stream is intended for LiFi and OCC. The first stream is transmitted at a very high frequency using the LED. The LED flickers in two different power levels creating consecutive sequences. A smartphone camera receives the sequences as binary successions, wherein the second data stream is modulated. The modulation is referred to as intensity-shift keying. A testbed prototype is implemented to demonstrate the proof-of-concept, which is also used to show the bit-error-rate performance of the proposed scheme.
关键词： hybrid system,intensity-shift keying (ISK),light-fidelity (LiFi),Optical camera communication (OCC)
更新于2025-09-19 17:13:59
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[IEEE 2019 Global LIFI Congress (GLC) - Paris, France (2019.6.12-2019.6.13)] 2019 Global LIFI Congress (GLC) - LiFi Reception from Organic Photovoltaic Modules Subject to Additional DC Illuminations and Shading Effects
摘要： In this paper, we study the performance of organic photovoltaic (OPV) modules as LiFi receivers in two specific configurations. The PV-based LiFi receiver is first exposed to an additional homogeneous light source with different intensity levels and then the influence of partial lighting is studied (shading effect). In both cases, we compare the sensibility and the cutoff frequency of LiFi transmission when the solar cell is operated either in short-circuit mode (i.e. when it is loaded with an active transimpedance amplifier) or in open circuit mode (i.e. when it is terminated with an high impedance passive load). While the OPV module performance decreases in open-circuit mode as a function of the DC illumination level, we observe an improvement of the cutoff frequency in short circuit mode. This result seems very promising for outdoor LiFi transmissions but also for indoor conditions where natural light can disturb LiFi communications. Theoretical explanations involving physical parameters for energy harvesting (carrier mobility, lumped series resistance) are proposed to justify the observed behaviors. Finally, experimental results of shaded solar cells are provided in the two operating modes (open-circuit and short-circuit). We show that sensibility and bandwidth of OPV modules strongly depend on both the shading configuration and the operating mode.
关键词： OPV,shading effects,LiFi,open-circuit mode,organic photovoltaic,short-circuit mode
更新于2025-09-16 10:30:52
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[IEEE 2019 Global LIFI Congress (GLC) - Paris, France (2019.6.12-2019.6.13)] 2019 Global LIFI Congress (GLC) - Design and Fabrication of Micro LEDs for High Data Rate LiFi Communications
摘要： In this research, we have investigated P-I-N structures based on InGaN/GaN materials suitable for different size and adapted to the requirements of device characterization. The fabrication has been performed using different designs. Besides, the optimization of the fabrication process has been performed for multi scaled device fabrication (ranging from 5×5 μm2 to 100×100 μm2) in terms of photolithography, etching, metal deposition and passivation. We have considered μ-photodiodes with planar and vertical configurations. Design and fabrication of specific coplanar RF electrical transmission lines have been performed in order to reduce the influence of parasitic capacitances. We have therefore evaluated the size effect on capacitance which affects the speed of the devices, and consequently the cut-off frequency. The reported cut-off frequency @ -3dB has been evaluated as 1.5 GHz for a diameter of 25μm. This result indicates a potential response for LiFi needs as a part of optical wireless secured communication technology.
关键词： LiFi,devices fabrication,frequency,III-nitrides
更新于2025-09-12 10:27:22
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Modeling the Random Orientation of Mobile Devices: Measurement, Analysis and LiFi Use Case
摘要： Light-fidelity (LiFi) is a networked optical wireless communication (OWC) solution for high-speed indoor connectivity for fixed and mobile optical communications. Unlike conventional radio frequency wireless systems, the OWC channel is not isotropic, meaning that the device orientation affects the channel gain significantly, particularly for mobile users. However, due to the lack of a proper model for device orientation, many studies have assumed that the receiver is vertically upward and fixed. In this paper, a novel model for device orientation based on experimental measurements of forty participants has been proposed. It is shown that the probability density function (PDF) of the polar angle can be modeled either based on a Laplace (for static users) or a Gaussian (for mobile users) distribution. In addition, a closed-form expression is obtained for the PDF of the cosine of the incidence angle based on which the line-of-sight (LOS) channel gain is described in OWC channels. An approximation of this PDF based on the truncated Laplace is proposed and the accuracy of this approximation is confirmed by the Kolmogorov-Smirnov distance (KSD). Moreover, the statistics of the LOS channel gain are calculated and the random orientation of a user equipment (UE) is modeled as a random process. The influence of random orientation on signal-to-noise-ratio (SNR) performance of OWC systems has been evaluated. Finally, an orientation-based random waypoint (ORWP) mobility model is proposed by considering the random orientation of the UE during the user’s movement. The performance of ORWP is assessed on the handover rate and it is shown that it is important to take the random orientation into account.
关键词： Laplace distribution,Optical wireless communications,light-fidelity (LiFi),receiver rotation,fading,device orientation,random waypoint
更新于2025-09-11 14:15:04
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Comparison of DCO-OFDM, ADO-OFDM, HDC-OFDM and HNC-OFDM for Optical Wireless Communications
摘要： This paper presents a new form of orthogonal frequency division multiplexing (OFDM) termed as hybrid noise cancelled asymmetrically clipped optical OFDM (HNC-OFDM) for optical wireless communication. This HNC-OFDM is formed by combining the concepts of noise cancelled asymmetrically clipped optical OFDM and DC biased optical OFDM (DCO-OFDM). HNC-OFDM has the same bit error rate (BER) performance and dimming flexibility but less complexity compared to the recently developed hybrid diversity combined OFDM. The optimum DC bias level for HNC-OFDM, DCO-OFDM and asymmetrically clipped DC biased optical OFDM is shown to depend on the target BER, the constellation size, the received signal to noise power ratio, the proportion of DCO-OFDM element, the link type, equalization, etc. Simulations results show that with an optimum bias, HNC-OFDM can outperform others in an average power limited channel, while DCO-OFDM is a better choice for a peak power limited channel.
关键词： optical wireless communication,Dimming,LiFi,visible light communication,OFDM
更新于2025-09-11 14:15:04
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All-optical notch filters for ultra-wideband chaotic communications
摘要： In this paper, a wideband all-optical notch ?lter is proposed using two cascaded modi?ed add-drop resonators from chalcogenide glass (ChG) and GaAsInP-InP waveguide materials. The system consists of ChG main ring and two small side rings called phase modulators made of the GaAsInP-InP materials. The plane waves are fed at the input and add ports, from which the chaotic signal outputs can be generated by the nonlinear e?ect induced into the center ring. The results have been simulated based on the scattering matrix method. Results have shown that the generated chaotic signals can be used for switching and secured communications. An ultra-fast switching time of ～ 2 attoseconds is achieved. Moreover, the chaotic signals can be ?ltered by the stop band ?lters (notch ?lters). The free spectral range (FSR) of two cascaded ChGs is 1494.8 nm. The output wavelength of the notch ?lters is tunable from 748.0–2242.2 nm and 2242.8–3737.0 nm. The band-stop of the notch ?lter is 1494.2 nm. This approach will allow the implementation of the compact, and integrated notch ?lters in an on-chip scale circuit, which is useful for both light ?delity (LiFi) and wireless ?delity (WiFi) applications.
关键词： WiFi,all-optical notch ?lters,chalcogenide glass,GaAsInP-InP,scattering matrix method,ultra-wideband chaotic communications,LiFi
更新于2025-09-10 09:29:36