Visible Light Communication Research Articles

Highly SNR uniformity and power efficient model for indoor VLC based on DCO-GFDM modulation

Abstract Innovation of new light emitting diodes (LEDs) distribution for indoor visible light communication (VLC) systems is necessary to mitigate challenges like signal-to-noise ratio (SNR) uniformity. In addition, creating proper lighting in indoor environments is essential for occupants’ comfort and energy efficiency, where uniform illuminance is needed. This article proposes optimum LEDs distribution to find higher illuminance uniformity based on various semi-angles of light half power and analyzes the best SNR uniformity. The higher SNR uniformity improves user experience by ensuring consistent data transmission quality throughout the room and maintaining a lower bit error rate (BER). The proposed VLC model comprises 16 illuminance units with 30 × 30 LED chips placed in the ceiling of a standard room (5 × 5 × 3 m3). Considering the reflections, the receiver’s delay spread is relatively high due to this higher number of transmitters. This VLC model is examined using a flexible advanced modulation based on multiple subcarriers in different scenarios to mitigate delay spread issues. Optical generalized frequency division multiplexing (OGFDM) modulation is utilized due to its high spectral efficiency and inter-symbol interference reduction. Employing the same power as the standard VLC model with 4 LED transmitters reveals a notable improvement in illuminance and SNR uniformities, power received, and illuminance and SNR values fulfilled by the proposed model.

Review of Design and Implementation of New Software Radio System based on GNU Radio and USRP

This paper provides a comprehensive review of the design and implementation of software-defined radio (SDR) systems based on the GNU Radio platform and Universal Software Radio Peripheral (USRP) hardware in China. The study highlights the evolution of wireless communication technologies, emphasizing the technical advantages of SDR, including flexibility, scalability, interference resistance, and cost-effectiveness. The analysis explores widely used software platforms (GNU Radio and LabVIEW) and hardware peripherals (USRP and HackRF One), comparing their specifications, functionality, and suitability for diverse communication scenarios.A detailed examination of recent Chinese academic research reveals numerous practical implementations, such as adaptive interference cancellation systems, dual-protocol transceivers, spectrum monitoring platforms, visible light communication (VLC) systems, and MIMO-OFDM architectures. These systems leverage the modularity of GNU Radio and the high performance of USRP to address challenges in real-time data processing, spectrum efficiency, and channel interference. Experimental results from case studies demonstrate advancements in packet error rate (PER) reduction, spectral efficiency (up to 10 bit/s/Hz), and interference suppression (e.g., 20 dB self-interference cancellation for full-duplex systems). Challenges such as hardware limitations, environmental interference, and synchronization issues are discussed, alongside proposals for future enhancements, including hardware upgrades, multi-platform integration, and algorithm optimization. The paper underscores the role of open-source SDR frameworks in democratizing wireless innovation while providing critical insights into emerging trends and practical constraints in software radio research.

Beyond 50 Gbps 100 m visible light laser communication single-transmitter-multi-receiver system utilizing triple branch neural network

In the forthcoming 6 G communication era, traditional electromagnetic spectra are increasingly inadequate to meet growing demands. Visible Light Communication (VLC) technology offers a promising high-speed solution due to its flexible deployment and cost-effectiveness. However, long-distance VLC applications are challenged by factors such as atmospheric turbulence and nonlinear distortions. To address these issues, laser diodes (LDs) with high modulation bandwidth and reliable, easily deployable channel estimation techniques are essential. This paper presents what we believe to be a novel visible light laser communication (VLLC) single-transmitter-multi-receiver system utilizing red, green, and blue (RGB) laser diodes. We successfully achieved a 100-meter free-space transmission using time-domain hybrid huffman coding (TDHHC) combined with a triple branch neural network (TBNN) technique. The system attained transmission rates of 51.05 Gbps in turbulence-free conditions and 46.5 Gbps under strong turbulence, while maintaining a bit error rate (BER) below the stringent 3.8E-3 threshold specified by the 7% hard decision forward error correction (HD-FEC) standard. To our knowledge, this represents the highest data rate recorded in a 100 m tri-color VLLC system.

Flip-GFDM complexity reduction for a power-efficient visible light communication system

Visible light communication (VLC) has emerged as a promising solution to the limitations of traditional radio frequency systems, leveraging LEDs for high-speed, interference-free data transmission. However, optical orthogonal frequency division multiplexing (OFDM) techniques such as Flip-OFDM face challenges including high peak-to-average power ratio (PAPR) and spectral inefficiency. This study introduces what we believe to be a novel flip-generalized frequency division multiplexing waveform (Flip-GFDM), named non-Hermitian Flip-GFDM (NH-Flip-GFDM), designed to reduce complexity. By eliminating Hermitian symmetry and halving the IFFT/FFT size, the proposed approach achieves significant computational savings, with about a 50% reduction in complexity. Simulation results reveal that NH-Flip-GFDM maintains comparable symbol error rate (SER) and bit error rate (BER) performance to traditional Flip-GFDM while reducing PAPR by approximately 2 dB over Flip-OFDM. These improvements position NH-Flip-GFDM as a power-efficient and cost-effective solution for next-generation VLC systems.

Robust Max–Min Fair Beamforming Design for Rate Splitting Multiple Access-Aided Visible Light Communications

Robust Max–Min Fair Beamforming Design for Rate Splitting Multiple Access-Aided Visible Light Communications

A Novel Clipping Noise-Free Transmission Scheme in OFDM-Based Visible Light Communications

A Novel Clipping Noise-Free Transmission Scheme in OFDM-Based Visible Light Communications

Adaptive Pre-Distortion Compensation for LED Nonlinear Distortion in VLC-OFDM Systems Using Frequency Symbol Spreading

This paper proposes an adaptive pre-distortion method for mitigating LED nonlinear distortion in Visible Light Communication (VLC)-OFDM systems. The inherent nonlinear characteristics of LEDs disrupt the orthogonality among OFDM subcarriers, causing signal distortion and performance degradation. To overcome this issue while minimizing computational complexity at the transmitter, we introduce a feedback-based nonlinear parameter estimation approach using the Least Squares Method (LSM) and Median Based Method (MBM). These estimated parameters are then fed back to the transmitter, enabling efficient adaptive pre-distortion based on the inverse function of the estimated nonlinear characteristics. This approach reduces computational costs at the transmitter compared to conventional methods requiring high-performance processing. Additionally, we incorporate Frequency Symbol Spreading (FSS) to further enhance robustness against channel impairments such as Rician fading by equalizing the Signal-to-Noise Ratio (SNR) across subcarriers. Simulation results under various channel conditions, including AWGN, Rician fading, and realistic multi-LED lighting scenarios, demonstrate a significant improvement in Bit Error Rate (BER) performance, validating both the effectiveness and practical advantages of the proposed approach.

High-Resolution Dimmable Augmented Spectral-Efficiency Discrete Multi-Tone Architecture Based on Hybrid Pulse-Width Modulation in Visible-Light Communications

Dimming control is an indispensable functionality for visible-light communication (VLC) that enables both illumination and data transmission. However, how to achieve both high-resolution dimming control and spectral-efficient communication is still an open problem. Therefore, a novel high-resolution dimmable augmented spectral-efficiency discrete multi-tone (HD-ASE-DMT) architecture is proposed in this paper. To address the limitation of low dimming resolution in a conventional pulse-width modulation (PWM) scheme, a hybrid PWM mechanism was first designed by combining the inter-symbol and intra-symbol PWM signals, which provided flexible and high-resolution two-tier dimming control. Furthermore, a reconstructed process was conceived to achieve the seamless integration of the hybrid PWM and the spectral-efficient ASE-DMT architecture. As a result, the proposed HD-ASE-DMT architecture maintains full compatibility with legacy ASE-DMT receivers, thus reducing the implementation complexity compared to the existing dimmable modulation schemes. Simulation results demonstrated that a two-orders-of-magnitude improvement in the dimming resolution was achieved by the HD-ASE-DMT architecture. Moreover, the spectral efficiency of the HD-ASE-DMT architecture was improved by 29.3% compared to the conventional scheme.

Luminous efficiency of InGaN/GaN-based green micro-LED improved by n-side graded quantum wells.

InGaN/GaN-based micro-light-emitting diodes (micro-LEDs) are considered as candidate technologies for the next generation display and visible light communication (VLC). In this study, we proposed an n-side graded indium content quantum well structure to improve the luminous efficiency and comprehensive performance of InGaN/GaN-based green micro-LED. The InGaN quantum wells with n-side graded indium content can improve the crystal quality, alleviate the quantum-confined Stark effect (QCSE), and improve the radiation recombination efficiency at low current. The experimental results demonstrate that the peak external quantum efficiency (EQE) of micro-LED with n-side graded indium content is improved by 10.4% compared to the micro-LED with traditional square quantum wells, and it has better color saturation. This work provides a feasible direction for the commercial production and application of high luminous efficiency green micro-LED.

Multi-input and multi-objective design for a mini-LED LCD integrated with MIMO visible light communication

Multi-input and multi-objective design for a mini-LED LCD integrated with MIMO visible light communication

Ultrafast White-Light System Combining a Blue Micro-LED with Organic Blend for Visible Light Communication and Solid-State Lighting

Ultrafast White-Light System Combining a Blue Micro-LED with Organic Blend for Visible Light Communication and Solid-State Lighting

Terahertz and visible light communication: progress, frontiers, and challenges

Terahertz and visible light communication: progress, frontiers, and challenges

21.79/17.49 Gbps Full-Duplex Visible Light Communication Enabled by Short-Cavity Blue and Green InGaN/GaN Laser Diodes

21.79/17.49 Gbps Full-Duplex Visible Light Communication Enabled by Short-Cavity Blue and Green InGaN/GaN Laser Diodes

Enhancement in power stratification efficiency of NOMA-MIMO-aided downlink indoor visible light communication networks

Enhancement in power stratification efficiency of NOMA-MIMO-aided downlink indoor visible light communication networks

Advancements in LED-based indoor visible light communication: A two-decade survey

Advancements in LED-based indoor visible light communication: A two-decade survey

Generation of 1319 nm Pulsed Vortex Laser by Annular Pumped Bonded Nd:YAG/V:YAG Crystal

Vortex lasers have shown significant advantages in fields such as quantum communication and optical detection due to their unique optical field structure. In this manuscript, we present a watt-level nanosecond Laguerre–Gaussian vortex beam from an end-pumped bonded Nd:YAG/V:YAG laser, which was pumped by a ring-shaped beam shaped by an axicon focusing system. By solving the transfer matrix of the resonator and designing a corresponding pump beam shaping system, mode matching between the LG01 beam and the annular pump beam was effectively achieved. The conditions for exciting the LG01 mode were theoretically calculated, and experimental results verified that the pump power required to excite the LG01 vortex beam is approximately twice that for exciting the fundamental Gaussian mode. Stable output of nanosecond lasers in the LG01 mode was achieved, with an output power of 1.943 W, a highest repetition rate of 291.3 kHz, a pulse width of 3.3 ns, and beam quality factors of Mx2=2.17 in the horizontal direction and My2=2.21 in the vertical direction. The results have significant value for applications such as visible light communication and high-resolution laser imaging.

All-optical implementation of an optoelectronic oscillator reservoir computer with an integrated spatial photonic processor.

Reservoir computing (RC), inspired by neural networks, has gained significant attention for tackling complex tasks such as recognition and classification. Most RC implementations are limited to software, which restricts processing speed, as reservoir outputs are often processed through slow, digital offline post-processing in previous work. To address these constraints, we propose a solution that combines a nonlinear time-delayed optoelectronic oscillator (OEO) with an integrated spatial photonic processor (ISPP) for online reservoir output processing. This approach leverages both temporal multiplexing and spatial processing, enabling high-speed, and parallel hardware implementation. We achieve enhanced performance in modulation format recognition (MFR) for visible light communication (VLC) signals using a photonic reservoir with 64 nodes. Tests on 16 widely used modulation formats at a 2 Gbps data rate over a 1.2 m VLC transmission link demonstrate that this spatiotemporal multiplexing technique can accurately classify all formats, achieving a state-of-the-art overall accuracy of 99.5%.

Simultaneous on-chip generation of violet, blue, cyan, green, yellow, orange, and red light from an octave-spanning infrared frequency comb.

An integrated, multi-spectral visible-light source could significantly benefit technologies such as displays, medical imaging, spectroscopy, visible-light communications, and astrophysics. However, despite recent advances in chip-scale visible lasers, simultaneously generating light of all colors in a single chip has been challenging. Existing solutions are either not suitable for full chip-scale integration, or are fundamentally difficult to scale. Here we demonstrate the simultaneous on-chip generation of infrared, red, orange, yellow, green, cyan, blue, and violet light. Leveraging the low loss, low dispersion, and high density of modes of an adiabatic multimode silicon nitride (SiN) microresonator, we use a single infrared pump of moderate power (∼130 mW) to produce an octave-spanning infrared frequency comb that is then converted to different portions of the visible spectrum. We measure non-mode-locked combs and soliton steps corresponding to mode-locked states, making our comb generator suitable for applications that demand either low or high coherence. Since the required pump power is compatible with high-power lasers demonstrated in the same SiN platform, our multi-octave light generator can be fully integrated in a chip-scale form factor. We envision that such a light source will be a catalyst for the development and deployment of miniaturized multi-spectral technologies for quantum systems, medical imaging, displays, and spectroscopy.

GaN Optoelectronic Integrated Chip with Multifunctions of Communication and Neuromorphic Computing

AbstractThe ultimate neuromorphic chip based on light‐stimulated artificial synapses requires suitable materials and platforms for optoelectronic integration. Herein, a GaN optoelectronic integrated chip with multifunctions of communication, sensing, and neuromorphic computing is proposed and fabricated on a GaN‐on‐Si light‐emitting diode (LED) epitaxial wafer. The monolithically integrated chip consists of an InGaN/GaN multiple‐quantum‐well LED and a GaN‐based optoelectronic synaptic metal‐oxide‐semiconductor field‐effect transistor connected in series. It can achieve multi‐mode switching, including self‐powered photodetector (PD), light‐emitting synapse, and gate‐voltage‐controlled light transmitter. For the PD mode, a great responsivity of 4393 A W−1 and a high specific detectivity of 1.56 × 1014 Jones are demonstrated. Notably, due to varying absorption of short wavelength light by different epitaxial layers, the integrated device shows differentiated wavelength selectivity for light illuminated from the front and back sides. When the integrated device is operating in synapse mode, excitatory postsynaptic currents induced by light stimuli can be read both optically and electrically with the assistance of built‐in optical‐to‐electrical‐to‐optical conversion. Moreover, direct bias‐voltage modulation and gate‐voltage modulation are both configured into this integrated device, achieving 60 and 5 Mbps modulation rates for visible light communication applications, respectively.

Achieving a Record Photoluminescence Quantum Yield in Green Light-Emitting Carbon-Centered Radicals with Nanosecond Emission Lifetimes.

Organic luminescent radicals possess considerable potential for applications in organic light-emitting diodes (OLEDs)-based visible light communication owing to their intrinsic advantages of nanosecond emission lifetimes and spin-allowed radiative transitions. However, the inherently narrow energy bandgap and multiple nonradiative channels of organic radicals make it difficult to achieve efficient green and blue light-emitting, which is not conducive to applying visible light communication in diverse fields. In this study, a series of carbon-centered radicals derived from N-heterocyclic carbenes are designed and synthesized, some of which exhibiting hybrid local and charge-transfer (HLCT) states that resulting in efficient green emission. The results of photophysical characterizations and theoretical calculations demonstrate that the luminescence efficiency is closely related to their emission states. This relationship inhibits the nonradiative channels while simultaneously opening the radiative channels of organic radicals exhibiting HLCT states but not those with locally excited states. Intriguingly, a high photoluminescence quantum yield value of up to 70.1% at 534 nm is observed, which is the highest among green light-emitting carbon-centered radicals reported to date. Based on this exceptional result, an OLED device is fabricated and achieved an external quantum efficiency of 8.8%. These results demonstrate its potential application in electroluminescent devices.