- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Indoor Visible Light Communications, Networking, and Applications
摘要： Light-emitting diodes (LEDs) are changing indoor wireless communications. Visible light communications (VLC) that use LEDs as transmitters is an emerging research area and has significant commercial potential. The light emitted from LEDs can simultaneously carry information and provide illumination. Due to the intrinsic characteristics of light, VLC is more secure, more power efficient, and can provide higher network data transmission rates than radio frequency (RF) communications. This paper describes state-of-the-art VLC systems including transmitters, receivers, and channel models. Modulation and networking algorithms for physical layer and cross-layer designs are discussed. These algorithms are designed considering practical constraints, such as the bandlimited channel, illumination requirements, and transmitted power limitations. Indoor localization algorithms are proposed, with a particular focus on fingerprinting. In addition, this paper introduces practical applications of VLC in many fields such as national defense, healthcare, robotics, and vehicle-to-vehicle communications. The paper concludes with a discussion of the challenges, opportunities, and future of VLC.
关键词： Visible light communications,modulation,optical wireless communications,visible light positioning,LEDs,networking
更新于2025-09-23 15:19:57
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Gallium nitride micro-light-emitting diode structured light sources for multi-modal optical wireless communications systems
摘要： Gallium nitride-based light-emitting diodes (LEDs) have revolutionized the lighting industry with their efficient generation of blue and green light. While broad-area (square millimetre) devices have become the dominant LED lighting technology, fabricating LEDs into micro-scale pixels (micro-LEDs) yields further advantages for optical wireless communications (OWC), and for the development of smart-lighting applications such as tracking and imaging. The smaller active areas of micro-LEDs result in high current density operation, providing high modulation bandwidths and increased optical power density. Fabricating micro-LEDs in array formats allows device layouts to be tailored for target applications and provides additional degrees of freedom for OWC systems. Temporal and spatial control is crucial to use the full potential of these micro-scale sources, and is achieved by bonding to pitch-matched complementary metal-oxide-semiconductor control electronics. These compact, integrated chips operate as digital-to-light converters, providing optical signals from digital inputs. Applying the devices as projection systems allows structured light patterns to be used for tracking and self-location, while simultaneously providing space-division multiple access communication links. The high-speed nature of micro-LED array devices, combined with spatial and temporal control, allows many modes of operation for OWC providing complex functionality with chip-scale devices.
关键词： Gallium nitride,structured light,light-emitting diodes,optical wireless communications
更新于2025-09-23 15:19:57
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Automatic Compensation for Defects of Laser Reflective Patterns in Optics-Based Auto-Focusing Microscopes
摘要： This paper summarizes recent work on the use of optical wireless links as a robust outdoor backhaul solution for small radio cells, such as WiFi, LTE and 5G, over distances between 20 and 200 m. Results of a 5-month outdoor field trial in Berlin, Germany, indicate that the visibility range was never below 180 m, with more than 1 km in 99% of all times during this period. Rate-adaptive transmission proved to improve the availability remarkably in the occasional presence of fog or sunlight. A mathematical model of the backhaul link including these impairments is presented and implemented to obtain an optimized link design. A prototype was realized, accordingly, using low-cost optoelectronic components and a 1 Gb/s baseband chipset. Gross data rates of 800, 500, and 225 Mb/s have been achieved in real-time operation over 20, 100, and 215 m outdoor link distance, respectively, with 2 ms latency at 95% load. Finally, we discuss further evolution towards 5G mobile networks.
关键词： Fronthaul,LTE,small cells,5G,Backhaul,LED,optical wireless communications
更新于2025-09-23 15:19:57
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Proof-of-Principle Experiment of a 20-kW-Average-Power Ka-Band Gyro-Traveling Wave Tube With a Cut-Off Waveguide Section
摘要： This paper summarizes recent work on the use of optical wireless links as a robust outdoor backhaul solution for small radio cells, such as WiFi, LTE and 5G, over distances between 20 and 200 m. Results of a 5-month outdoor field trial in Berlin, Germany, indicate that the visibility range was never below 180 m, with more than 1 km in 99% of all times during this period. Rate-adaptive transmission proved to improve the availability remarkably in the occasional presence of fog or sunlight. A mathematical model of the backhaul link including these impairments is presented and implemented to obtain an optimized link design. A prototype was realized, accordingly, using low-cost optoelectronic components and a 1 Gb/s baseband chipset. Gross data rates of 800, 500, and 225 Mb/s have been achieved in real-time operation over 20, 100, and 215 m outdoor link distance, respectively, with 2 ms latency at 95% load. Finally, we discuss further evolution towards 5G mobile networks.
关键词： Backhaul,optical wireless communications,small cells,Fronthaul,LTE,LED,5G
更新于2025-09-23 15:19:57
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[IEEE 2019 1st AL-Noor International Conference for Science and Technology (NICST) - Sulimanyiah - Kurdistan Region- IRAQ, Iraq (2019.10.25-2019.10.29)] 2019 1st AL-Noor International Conference for Science and Technology (NICST) - Regulation of height position-multi-grid motor shelter on laser electrohydraulic system of automatic beam
摘要： Communications security is a critical and increasingly challenging issue in wireless networks. A well-known approach for achieving information-theoretic secrecy relies on deploying artificial noises to blind the intruders’ interception in the physical layer. However, this approach requires a static channel condition for the transmitter and receiver to generate and offset the controllable artificial noise, which can hardly be implemented in real wireless environments. In this paper, we explore the feasibility of symbol obfuscation to defend against the passive eavesdropping attack and fake packet injection attack during the wireless communications. We propose a multiple inter-symbol obfuscation (MIO) scheme, which utilizes a set of artificial noisy symbols (symbols key) to obfuscate the original data symbols in the physical layer. MIO can effectively enhance the wireless communications security. On the one hand, an eavesdropper, without knowing the artificial noisy symbols, cannot correctly decrypt the obfuscated symbols from the eavesdropped packets. On the other hand, a legitimate receiver can easily check the integrity of the symbols key and then reject the fake packets from the received packets. The security analysis reveals that, without considering the initial key, the MIO scheme can achieve information-theoretic secrecy against the passive eavesdropping attack and computational secrecy against the fake packet injection attack. Moreover, we have implemented our approach in a USRP2 testbed and conducted simulations with Simulink tools to validate the effectiveness of MIO in enhancing wireless communications security.
关键词： physical layer security,Wireless communications security,information-theoretic secrecy,artificial noise
更新于2025-09-23 15:19:57
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Signal Quality Assessment for Transdermal Optical Wireless Communications under Pointing Errors
摘要： In this paper, we assess the signal quality of the out-body to in-body optical communication link, which can be used as a fundamental enabler of novel biomedical appliances, such as medical implants, as well as biological and chemical components monitoring. In particular, we present a mathematical understanding of the transdermal system, which takes into account the optical channel characteristics, the integrated area limitations of the in-body unit, the transceivers’ pointing errors and the particularities of the optical units. Moreover, to accommodate the propagation characteristics, we present a novel simplified, but accurate, transdermal path-gain model. Finally, we extract low-complexity closed-form expressions for the instantaneous and average signal to noise ratio of the transdermal optical link (TOL). Numerical and simulation results are provided for several insightful scenarios and reveal that pointing errors can significantly affect the reliability and effectiveness of the TOL; hence, it should be taken into account in the analysis and design of such systems.
关键词： optical wireless communications,pointing errors,transdermal optical wireless links
更新于2025-09-19 17:15:36
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Ionic permeability and interfacial doping of graphene on SiO <sub/>2</sub> measured with Terahertz photoconductivity measurements
摘要： In the field of radio-frequency (RF) communications, the multiple-input multiple-output (MIMO) strategy allows us to attain a higher rate of data transfer due to the multipath-rich environment. In contrast, it is challenging to achieve the same rate in a highly correlated channel that is specific to optical wireless communications. In this paper, we propose the novel concept of an element-by-element optical MIMO system that enables the interference-free reception of parallel symbol streams; it achieves this by using an angular filter (AF) with a narrow transparent window. The AF consists of a one-dimensional photonic crystal, and the angular selectivity is obtained by using the extremely small wave vector regime. We demonstrate that the capacity of the proposed system increases linearly with the minimum number of transmit source elements and receive detectors, which is similar to conventional RF MIMO systems.
关键词： Angular filter,MIMO,capacity,visible light communications,photonic crystal,spatial multiplexing,optical wireless communications
更新于2025-09-19 17:13:59
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[IEEE 2019 International Conference on Optical MEMS and Nanophotonics (OMN) - Daejeon, Korea (South) (2019.7.28-2019.8.1)] 2019 International Conference on Optical MEMS and Nanophotonics (OMN) - Subwavelength sampled photonics waveguides in silicon nitride for efficient fiber mode-matching
摘要： This paper summarizes recent work on the use of optical wireless links as a robust outdoor backhaul solution for small radio cells, such as WiFi, LTE and 5G, over distances between 20 and 200 m. Results of a 5-month outdoor field trial in Berlin, Germany, indicate that the visibility range was never below 180 m, with more than 1 km in 99% of all times during this period. Rate-adaptive transmission proved to improve the availability remarkably in the occasional presence of fog or sunlight. A mathematical model of the backhaul link including these impairments is presented and implemented to obtain an optimized link design. A prototype was realized, accordingly, using low-cost optoelectronic components and a 1 Gb/s baseband chipset. Gross data rates of 800, 500, and 225 Mb/s have been achieved in real-time operation over 20, 100, and 215 m outdoor link distance, respectively, with 2 ms latency at 95% load. Finally, we discuss further evolution towards 5G mobile networks.
关键词： 5G,Fronthaul,LTE,Backhaul,small cells,optical wireless communications,LED
更新于2025-09-19 17:13:59
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Scaled-time OFDM experiments for channels exceeding the cyclic prefix
摘要： Wireless communications experiments at high user velocities can be performed with much less effort at lower velocities by using time-stretching techniques. time-stretching techniques do not consider the case of channel impulse responses exceeding the length of the cyclic prefix (CP). This is the case in any real-world OFDM system. In particular, multipath scenarios caused by relay nodes commonly found in public railways have a late, strong channel tap. In this work, the authors propose a time-stretching technique that preserves the effects of the insufficient CP with negligible error and without channel knowledge.
关键词： cyclic prefix,time-stretching,wireless communications,OFDM,high user velocities
更新于2025-09-19 17:13:59
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Dynamic channel selection in wireless communications via a multi-armed bandit algorithm using laser chaos time series
摘要： Dynamic channel selection is among the most important wireless communication elements in dynamically changing electromagnetic environments wherein, a user can experience improved communication quality by choosing a better channel. Multi-armed bandit (MAB) algorithms are a promising approach that resolve the trade-off between channel exploration and exploitation of enhanced communication quality. Ultrafast solution of MAB problems has been demonstrated by utilizing chaotically oscillating time series generated by semiconductor lasers. in this study, we experimentally demonstrate a MAB algorithm incorporating laser chaos time series in a wireless local area network (WLAN). Autonomous and adaptive dynamic channel selection is successfully demonstrated in an IEEE802.11a-based, four-channel WLAN. Although the laser chaos time series is arranged prior to the WLAN experiments, the results confirm the usefulness of ultrafast chaotic sequences for real wireless applications. In addition, we numerically examine the underlying adaptation mechanism of the significantly simplified MAB algorithm implemented in the present study compared with the previously reported chaos-based decision makers. This study provides a first step toward the application of ultrafast chaotic lasers for future high-performance wireless communication networks.
关键词： WLAN,IEEE802.11a,laser chaos time series,wireless communications,multi-armed bandit algorithm,Dynamic channel selection
更新于2025-09-19 17:13:59