- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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[IEEE 2019 25th International Workshop on Thermal Investigations of ICs and Systems (THERMINIC) - Lecco, Italy (2019.9.25-2019.9.27)] 2019 25th International Workshop on Thermal Investigations of ICs and Systems (THERMINIC) - Assessment of the validity of multi-domain LED model parameters in a broad current and temperature range
摘要： In this paper, a power switched, baseband modulation technique for visible light communications (VLC) is proposed and a theoretical model is constructed. It is shown that this technique, called single edge position modulation (SEPM), offers the unique performance characteristic that the communication properties reliability and power and spectral efficiency are invariable over a wide range of dimming levels. It is demonstrated that dimming robustness is obtained by increasing the number of bits per symbol. SEPM is compared with contemporary used baseband power switched modulation techniques for VLC that support dimming. The number of bits per symbol can be chosen to make a compromise between the dimming range over which reliability robustness is obtained on one hand, and the level of power and spectral efficiency on the other hand.
关键词： Modulation,visible light communications,reliability,Monte Carlo simulation,synchronization
更新于2025-09-23 15:19:57
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The spectral efficiency augmented HACO-OFDM based visible light communications
摘要： The conventional hybrid asymmetrically clipped optical orthogonal frequency division multiplexing (HACO-OFDM) has an obvious spectral efficiency loss due to the fact that the real part of the even subcarriers are not utilized. This paper proposes a scheme to augment the spectral efficiency of HACO-OFDM. In this scheme, more spectrum resources are exploited because the real part of selected even subcarrier group is utilized for data modulation at different depths. When the same modulation orders are used, the proposed scheme is able to achieve higher spectral efficiency than HACO-OFDM at the cost of acceptable increased computational complexity. When this scheme takes 5 depths, the joint modulation scheme uses 16QAM-4PAM and 64QAM-4PAM, the spectral efficiency of the proposed scheme can be increased by 31.33% and 23.48%, respectively. Moreover, compared with HACO-OFDM, the proposed scheme has advantages of lower PAPR and higher immunity to LED nonlinearity.
关键词： Visible light communications,HACO-OFDM,ASE-DMT
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 IEEE 30th Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) - Istanbul, Turkey (2019.9.8-2019.9.11)] 2019 IEEE 30th Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) - Hybrid Super-Nyquist CAP Modulation based VLC with Low Bandwidth Polymer LEDs
摘要： Visible light communication systems often suffer from high frequency attenuation when transmitting out-of-band. This effect has been ameliorated by multi-band modulations such as multi-band carrier-less amplitude and phase (m-CAP), which minimises the effect of decreased high frequency magnitude and maximises signal-to-noise ratio-per-sub-band. On the other hand, in the pass-band region, super-Nyquist CAP (SCAP) can offer throughput improvements with no additional complexity at the receiver, at the cost of bit error rate. We propose, for the first time, a new hybrid SCAP modulation format that takes advantageous of both SCAP (i.e. overlapped sub-bands within the modulation bandwidth) and conventional m-CAP (orthogonally spaced bands outside the modulation bandwidth) while maintaining isolation between noise sources. We show higher baud rates within the passband region whilst supporting out-of-band transmission at lower error vector magnitudes.
关键词： modulation,digital signal processing,Carrier-less amplitude and phase modulation,visible light communications
更新于2025-09-19 17:13:59
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Metasurface-enabled interference mitigation in visible light communication architectures
摘要： Light can be used for wireless information transmission apart from illumination; that is the key idea behind visible-light communication (VLC), one of the disruptive technologies of our days. It combines remarkably high data rates due to ultrashort wavelengths with huge reliability and security due to small distances; nevertheless, it substantially suffers from interference of neighboring light sources in multiple-link configurations. In this manuscript, we investigate a pair of light emitting diodes interfering each other and propose a simple nanoslit metasurface that radically increases the directivity of the transmitting beams. As a result, enhancement of the signal-to-interference ratio by several orders of magnitude is reported. The considered generic setup retains its beneficial features in the presence of realistic design defects and, accordingly, may inspire standardization efforts towards the adoption of VLC in next-generation heterogeneous communication networks.
关键词： directivity,metasurface,visible-light communications,radiation pattern,indoor environment
更新于2025-09-19 17:13:59
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Sub-carrier Loading Strategies for DCO-OFDM LED Communication
摘要： LEDs, particularly those used for Visible Light Communications (VLC), have a limited bandwidth, while above their 3 dB bandwidth, the roll-off is relatively gentle. If the modulation bandwidth would be limited to the 3 dB LED bandwidth, the achievable rate would be unacceptably constrained. Hence, effective communication systems need to optimize the use of bandwidth significantly above this 3 dB point. Orthogonal Frequency Division Multiplexing (OFDM) is a popular method to fine-tune the amount of power and constellation as a function of the channel response over different frequencies. Various power and bit loading strategies have been proposed and simulated in literature, but their performance was not captured in expressions. This manuscript derives these for optimal waterfilling, uniform and pre-emphasized power loading for the LED channel, that severely attenuates high frequencies. We also investigate the influence of practical discrete constellations and verify our new results experimentally. Interestingly, simple uniform loading only falls less than 1～2% short of the throughput achieved by waterfilling, but when we restrict OFDM to discrete QAM constellation sizes, the penalty for uniform loading is 1.5 dB. Inspired by the good performance of uniform power loading, we propose an algorithm to find the best discrete bit loading for uniform power within an optimized band. As pre-emphasis is nonetheless attractive because a flattened channel does not need adaptive sub-carrier loading, we quantify its penalty. This can be modest provided that the system can adapt its transmit bandwidth, thereby adaptively switching upper sub-carriers to zero power.
关键词： Orthogonal Frequency Division Multiplexing (OFDM),pre-emphasis,power loading strategies,LED channel,QAM constellation sizes,uniform loading,waterfilling,Visible Light Communications (VLC)
更新于2025-09-16 10:30:52
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[IEEE IEEE INFOCOM 2019 - IEEE Conference on Computer Communications Workshops (INFOCOM WKSHPS) - Paris, France (2019.4.29-2019.5.2)] IEEE INFOCOM 2019 - IEEE Conference on Computer Communications Workshops (INFOCOM WKSHPS) - Real-Time Experimental Demonstration of Multi-band CAP Modulation in a VLC System with Off-the-Shelf LEDs
摘要： We demonstrate, for the ?rst time, m-CAP modulation using off-the-shelf LEDs in a VLC in real time experimental setup using ?eld programmable gate arrays based in universal software radio peripherals (USRPs). We demonstrate transmission speeds up to ～30 Mb/s can be achieved, which supports high de?nition television streaming.
关键词： real time,?eld programmable gate array,visible light communications,modulation,Digital signal processing
更新于2025-09-12 10:27:22
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[IEEE 2019 15th International Conference on Telecommunications (ConTEL) - Graz, Austria (2019.7.3-2019.7.5)] 2019 15th International Conference on Telecommunications (ConTEL) - A Flexible OLED based VLC Link with m-CAP Modulation
摘要： In recent years there has been a growing interest in using organic light emitting diodes (OLEDs) for illumination in indoor environments. They offer attractive features such as flexibility and large active areas at a low cost; they are energy efficient and have higher illumination levels compared to silicone based LEDs. In addition, the utilization of OLEDs have increased in devices such as smart mobile phones and TVs because of their low thickness. This paper investigates the performance of an OLED based visible light communications (OVLC) system, using a curved and flat OLED with multiband carrierless amplitude and phase (m-CAP) modulation for m = 2 at different angles of incidence on the optical receiver. It is shown that the BER performance is improved (i.e., below the forward error correction (FEC) limit of 3.8×10-3) with the curved OLED when the optical receiver moving along a circular path for the viewing angles greater 40o compared to the flat OLED, which is advantageous in device to device communications.
关键词： m-CAP modulation,flexible organic LEDs,visible light communications
更新于2025-09-12 10:27:22
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[IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - Performance of Indoor Visible Light Communication System Under Random Placement of LEDs
摘要： In this paper, the performance of indoor visible light communication (VLC) system with randomly deployed light-emitting-diodes (LED) using Matern hardcore point process (MHCP) is analyzed and compared with existing random geometries like binomial point process (BPP) and fixed geometries such as circular and square. It is well known fact that the signal-to-noise-ratio (SNR) profile inside the room changes with respect to LED placement as well as receiver’s position. In order to achieve uniform SNR across the room, the proposed work uses MHCP based LED placement at the transmitter and a single photodiode (PD) at the receiver. Simulation results show that random placement of LED using MHCP configuration results in a much more uniform SNR profile inside the room than the random BPP and conventional circular and square LED placements. Further, our results also show that by deploying MHCP based LED placement, the average SNR across the room increases.
关键词： uniform signal-to-noise-ratio,Matern hardcore point process,visible light communications
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