- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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[IEEE 2019 4th International Conference on Mechanical, Control and Computer Engineering (ICMCCE) - Hohhot, China (2019.10.24-2019.10.26)] 2019 4th International Conference on Mechanical, Control and Computer Engineering (ICMCCE) - Laser Molten Pool Temperature Detecting Based on Recursive Estimation in 3D Printing
摘要： Free-space optical communication links operating over lognormal turbulence channels using on-off keying (OOK) are studied in this paper. Such systems can suffer from irreducible error floors that result from the use of demodulation with fixed and unoptimized detection thresholds. The resulting error floors are analyzed for the general case of low- and high-state offsets (i.e., finite extinction ratios). An electrical signal-to-noise ratio (SNR) optimized detection system is applied. The system uses the electrical SNRs to implement adaptive detection thresholds and eliminate the error floors. The system can accommodate operation with finite extinction ratios, as it uses the method of moments and maximum likelihhod estimation techniques to estimate the low- and high-state offsets and electrical SNR. Numerical results show that the SNR gap between the electrical-SNR-optimized detection system and the adaptive detection system is 2.3 dB at a bit-error rate of 10?5 without a state offset. The SNR gap increases to 4.5 dB with a state offset of ξ = 0.2.
关键词： Atmospheric turbulence,FSO,on-off keying,optical wireless communications
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE Regional Symposium on Micro and Nanoelectronics (RSM) - Genting Highland, Pahang, Malaysia (2019.8.21-2019.8.23)] 2019 IEEE Regional Symposium on Micro and Nanoelectronics (RSM) - Simulation and Optimization of Emitter Thickness for Indium Arsenide-Based Thermophotovoltaic Cell
摘要： Free-space optical communication links operating over lognormal turbulence channels using on-off keying (OOK) are studied in this paper. Such systems can suffer from irreducible error floors that result from the use of demodulation with fixed and unoptimized detection thresholds. The resulting error floors are analyzed for the general case of low- and high-state offsets (i.e., finite extinction ratios). An electrical signal-to-noise ratio (SNR) optimized detection system is applied. The system uses the electrical SNRs to implement adaptive detection thresholds and eliminate the error floors. The system can accommodate operation with finite extinction ratios, as it uses the method of moments and maximum likelihood estimation techniques to estimate the low- and high-state offsets and electrical SNR. Numerical results show that the SNR gap between the electrical-SNR-optimized detection system and the adaptive detection system is 2.3 dB at a bit-error rate of 10?5 without a state offset. The SNR gap increases to 4.5 dB with a state offset of ξ = 0.2.
关键词： Atmospheric turbulence,FSO,on-off keying,optical wireless communications
更新于2025-09-19 17:13:59
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Photonic generation of tunable phase microwave signal using a feed-back controlled birefringent polarization rotator
摘要： The photonic generation of microwaves or millimeter waves using the beat note of two lightwaves is an attractive technique for fiber-wireless communication systems because it enables high-frequency selectivity over the entire radio-frequency region as well as high-speed phase control via electro-optic phase modulators. In this paper, we propose a novel phase control method with small phase drift that uses the polarization dependence of electro-optic phase modulators combined with a feedback-controlled birefringent polarization rotator. The high stability and ultrafast phase shift keying operation of an optically generated microwave signal are experimentally demonstrated.
关键词： optical beat note,fiber-wireless communications,birefringent optical fiber,photonic microwave generation
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE BiCMOS and Compound semiconductor Integrated Circuits and Technology Symposium (BCICTS) - Nashville, TN, USA (2019.11.3-2019.11.6)] 2019 IEEE BiCMOS and Compound semiconductor Integrated Circuits and Technology Symposium (BCICTS) - Integrated CMOS-Compatible Mode-Locked Lasers and Their Optoelectronic Applications
摘要： Free-space optical communication links operating over lognormal turbulence channels using on-off keying (OOK) are studied in this paper. Such systems can suffer from irreducible error floors that result from the use of demodulation with fixed and unoptimized detection thresholds. The resulting error floors are analyzed for the general case of low- and high-state offsets (i.e., finite extinction ratios). An electrical signal-to-noise ratio (SNR) optimized detection system is applied. The system uses the electrical SNRs to implement adaptive detection thresholds and eliminate the error floors. The system can accommodate operation with finite extinction ratios, as it uses the method of moments and maximum likelihhod estimation techniques to estimate the low- and high-state offsets and electrical SNR. Numerical results show that the SNR gap between the electrical-SNR-optimized detection system and the adaptive detection system is 2.3 dB at a bit-error rate of 10?5 without a state offset. The SNR gap increases to 4.5 dB with a state offset of ξ = 0.2.
关键词： Atmospheric turbulence,FSO,on-off keying,optical wireless communications
更新于2025-09-19 17:13:59
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Towards Energy Neutral Wireless Communications: Photovoltaic Cells to Connect Remote Areas
摘要： In this work, we have designed, developed and deployed the world’s first optical wireless communication (OWC) system using off-the-shelf lasers and solar photovoltaics. Four bidirectional OWC prototypes have been installed on the Orkney Islands of Scotland at a 30 m link distance for the provision of high-speed internet access to two residential properties. The silicon-made solar panels can harvest power up to 5 W from sunlight and they offer data rates as high as 8 Mb/s. Using additional analogue processing, data rates higher than the existing landline broadband connection are achieved. This breakthrough opens the development path to low cost, self-powered and plug-and-play free-space optical (FSO) systems.
关键词： communication systems,free-space optical communication,light communication,solar energy,optical wireless communications,energy harvesting
更新于2025-09-16 10:30:52
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A UAV-Mounted Free Space Optical Communication: Trajectory Optimization for Flight Time
摘要： In this work, we address the trajectory optimization of a fixed-wing unmanned aerial vehicle (UAV) using free space optical communication (FSOC). Here, we focus on maximizing the flight time of the UAV by considering practical constraints for wireless UAV communication, including limited propulsion energy and required data rates. We find optimized trajectories in various atmospheric environments (e.g., moderate-fog and heavy-fog conditions), while also considering the channel characteristics of FSOC. In addition to maximizing the flight time, we consider the energy efficiency maximization and operation-time minimization problem to find the suboptimal solutions required to meet those constraints. Furthermore, we introduce a low-complexity approach to the proposed framework. In order to address the optimization problem, we conduct a bisection method and sequential programming and introduce a new feasibility check algorithm. Although our design considers suboptimal solutions owing to the nonconvexity of the problems, our simulations indicate that the proposed scheme exhibits a gain of approximately 44.12% in terms of service time when compared to the conventional scheme.
关键词： trajectory design,Free space optical communication (FSOC),wireless communications with an unmanned aerial vehicle (UAV),flight time maximization,UAV-mounted FSOC
更新于2025-09-12 10:27:22
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Comparison of Optical OFDM and M-PAM for LED-Based Communication Systems
摘要： Light-emitting diode (LED)-based communications, such as visible light communications (VLC) and infrared (IR) communications, are candidate techniques to provide short-range and high-speed data transmission. In this paper, M-ary pulse amplitude modulation (M-PAM), used as a high bandwidth efficiency scheme, is compared with three well-known optical orthogonal frequency division multiplexing (OFDM) schemes. Considering the bandwidth limit and constrained peak transmitted power characteristics of LEDs, a bit loading algorithm and single-tap equalizer with an optimized modulation index are used for the optical OFDM schemes tested. To reduce the inter-symbol interference caused by the bandlimited channel, an optimized pulse shape and a minimum mean squared error (MMSE) equalizer are applied to the M-PAM system. From numerical results, M-PAM can provide a substantially higher data rate than OFDM for bandlimited channels. When the channel bandwidth is ample compared with the symbol rate, optical OFDM outperforms M-PAM.
关键词： pulse shaping,infrared communications,M-PAM,OFDM,bit loading,visible light communications,MMSE equalizer,optical wireless communications
更新于2025-09-11 14:15:04
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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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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz2018) - Nagoya, Japan (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Millimeter-Wave Technologies for Body-Centric Applications
摘要： Body-centric wireless networks constitute an attractive next-generation wireless technology representing a cognitive interface to higher-level networks. Recently, the 60 GHz band has been identified as highly promising for body-centric network wireless technologies. A massive deployment of wireless devices equipped with 60 GHz Tx / Rx modules is foreseen in coming years. The corresponding new usages and services will involve near-field interaction of radiating devices with the human body, both in terms of the body impact on wireless device performances as well as in terms of user exposure. This presentation will provide an overview of main features and recent advances in the field of antenna / human body interactions in the 60 GHz band.
关键词： wireless,communications,next-generation,attractive,body-area
更新于2025-09-10 09:29:36
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Independent control of harmonic amplitudes and phases via a time-domain digital coding metasurface
摘要： Harmonic manipulations are important for applications such as wireless communications, radar detection and biological monitoring. A general approach to tailor the harmonics involves the use of additional amplifiers and phase shifters for the precise control of harmonic amplitudes and phases after the mixing process; however, this approach leads to issues of high cost and system integration. Metasurfaces composed of a periodic array of subwavelength resonators provide additional degrees of freedom to realize customized responses to incident light and highlight the possibility for nonlinear control by taking advantage of time-domain properties. Here, we designed and experimentally characterized a reflective time-domain digital coding metasurface, with independent control of the harmonic amplitude and phase. As the reflection coefficient is dynamically modulated in a predefined way, a large conversion rate is observed from the carrier signal to the harmonic components, with magnitudes and phases that can be accurately and separately engineered. In addition, by encoding the reflection phases of the meta-atoms, beam scanning for multiple harmonics can be implemented via different digital coding sequences, thus removing the need for intricate phase-shift networks. This work paves the way for efficient harmonic control for applications in communications, radar, and related areas.
关键词： time-domain digital coding metasurface,metasurfaces,radar detection,nonlinear control,harmonic manipulations,wireless communications,beam scanning,biological monitoring
更新于2025-09-10 09:29:36