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Visible-light communication (VLC) has emerged as a promising technology to provide the very high-throughput wireless communications demanded by beyond-fifth-generation (B5G) applications. However, few works are found in the literature regarding the integration of VLC systems with other wireless communications technologies and with access networks. In this context, and as a proof of concept, we implement and experimentally evaluate a hybrid network architecture based on VLC, radio-over-fiber (RoF), free space optics (FSO), fiber-wireless (FiWi), and millimeter-waves (mm-waves) for B5G applications. Such optical networks make use of fiber-optic links based on RoF technology as backhauls, whereas their fronthauls might be either by FSO or RoF. Finally, a triple-wireless-access network is ensured by VLC, FiWi, and mm-wave links. The latter use a real 5G new radio (5G NR) signal. The system performance is evaluated in terms of a root mean square error vector magnitude (EVMRMS) parameter in accordance with the 3rd-Generation Partnership Project (3GPP) requirements. The experimental results demonstrate a total maximal theoretical throughput of approximately 1.66 Gbps, aligning with the digital performance requirements set by 3GPP. [ABSTRACT FROM AUTHOR]

Visible light communication (VLC) has recently gained significant attention due to its broad spectrum and advantages over radio frequency systems. VLC typically utilizes light-emitting diodes or laser diodes as a light source, which requires real and positive signals through intensity modulation and direct detection. Direct current-biased optical orthogonal frequency division multiplexing is a common type of modulation used in VLC. However, this technique suffers from a high peak-to-average power ratio (PAPR), which causes clipping distortions at the light source. On the other hand, generalized frequency division multiplexing (GFDM) technology offers high flexibility, high spectrum efficiency, and less out-of-band and PAPR, making it a promising technology for VLC systems but at the cost of complexity. This study proposes a novel real-signal GFDM for VLC, eliminating the need for Hermitian symmetry to reduce computational complexity. This method aims to reduce computational complexity while maintaining system performance. It significantly reduces the required number of complex multiplication and addition by lowering the IFFT/FFT size to half compared to traditional methods. The new approach reduces the complexity and size of hardware and power consumption compared to the conventional DCO-GFDM, making it a more practical solution for the next communications generations. [ABSTRACT FROM AUTHOR]

Nowadays, polarization division multiplexing (PDM) employing different states of polarizations (SOP) is a prominent candidate to offer high capacity and improved performance. However, the incorporation of PDM in indoor wireless optical communication (WOC) systems is limited to horizontal and vertical SOPs only. Therefore, in this research article, a cost-effective and high capacity 90 Gbps non-return to zero (NRZ) line coding based 18 channels VLC system is presented by incorporating red–green–blue laser diodes (RGB LDs). Performance investigations of different SOPs such as SOP 0°, SOP 45°, and SOP 90° are carried out at diverse VLC link distances in terms of log BER and Q factor. Results revealed that the proposed VLC system can successfully cover the 6 m distance and red LD together with SOP0 is found to be the highest performing. [ABSTRACT FROM AUTHOR]

Despite its potential for high-speed data transmission, visible light communication (VLC) technology faces significant challenges in achieving reliable real-time audio streaming due to interference, signal degradation, and synchronization issues. These limitations hinder the widespread adoption of VLC technology, especially in high-quality audio transmission. This paper introduces a novel VLC transceiver design incorporating advanced interference-resilient protocols, dynamic frame structuring, and robust error correction algorithms to enhance audio streaming performance. The proposed system achieves a signal-to-noise ratio (SNR) of 45 dB, reduces the bit error rate (BER) by up to four orders of magnitude to $1 \times 10^{-6}$ , and lowers the total latency by 50%. Furthermore, synchronization errors are reduced by 66.7%, while the mean opinion score (MOS) reaches 4.8, and the objective difference grade (ODG) improves to -0.5. The comparative analysis demonstrates significant advantages over Wi-Fi (802.11ac), VLC IM/DD, and state-of-the-art VLC systems. These findings establish the proposed system as a reliable solution for real-time, high-fidelity audio applications and a foundation for extending VLC technology to broader domains.

Summary: A comparative analysis of 3D positioning error for two different configurations using different layouts of visible light communication (VLC) systems is presented in this paper. The Received Signal Strength (RSS) has been implemented for indoor localization systems using Line‐of‐Sight (LoS) and diffused reflection signals. The room size for configuration‐1 is 5 m × 5 m × 3 m, and the distance between adjacent LEDs is 2.5 m, 2.00 m, and 1.5 m for cases‐1, case‐2, and case‐3, respectively, whereas the room size for configuration‐2 is 7 m × 7 m × 5 m, and the separation between the LEDs is 3.5 m, 3 m, and 2.5 m for their respective cases. Through investigation, it has been shown that when only LS signal is considered, the separation between LEDs may not be an issue because positioning error changes by a very small amount as the separation between LEDs changes. The results show that as the distance between adjacent LEDs decreases, the received signal strength for LoS and L‐R1 signals increases. However, positioning error and BER rise, while the bit rate falls. Furthermore, the positioning error Vs receiver plane height for all three cases in configuration‐1 is the same up to a height of 2.89 m, whereas the positioning error in configuration‐2 is the same up to 4.4 m for all cases. The positioning error for case‐1 decreases as the height in configuration‐1 exceeds 2.89 m. Similarly, after reaching a height of 4.4 m for case‐2, the positioning error in configuration‐2 decreases. The LoS positioning error versus semi angle φ1/2 of the LED as well as the FOV of the receiver has been simulated for different positions of the receiver in configuration‐1. The investigation shows that the minimum positioning error is achieved at φ1/2 and FOV equal to 66.660 for all the positions of the receiver in the room. Thus, before configuring a practical indoor VLC geometrical model, proper VLC configurations such as LED separation, FOV of the receiver, semi angle of LED, and receiver height should be chosen based on the room dimensions. [ABSTRACT FROM AUTHOR]

(In)GaN microLEDs have reached a high degree of maturity due to their development in the lighting industry. Their robustness and high efficiency make them ideal candidates for high‐brightness, high‐resolution micro‐displays. Beyond display applications, microLEDs are being explored for non‐display uses, including wireless Visible Light Communication (VLC) and parallel communication via multicore fiber. This study investigates short‐range chip‐to‐chip optical communication using InGaN/GaN microLEDs and micro Photodiodes (microPDs). Leveraging processes developed for micro‐displays, we address the challenges of integrating GaN microLEDs and microPDs on ASICs. We outline the main figures of merit, including expected energy efficiency, optical coupling to multicore fibers or waveguides, and the spectral efficiency of InGaN/GaN microPDs correlated with TCAD simulation and experimental transmission results. Our study highlights the potential of GaN microLEDs and microPDs for massively parallel, energy‐efficient data transmission, paving the way for innovative short‐range and energy‐efficient optical communication solutions. [ABSTRACT FROM AUTHOR]

Estimating the optical power distribution in a room in order to assess the performance of a visible light communication (VLC) system is nothing new. It can be estimated using a Monte Carlo optical ray tracing algorithm that sums the contribution of each ray on the reception plane. For now, research has focused on rectangular parallelepipedic rooms with single-textured walls, when studying indoor applications. This article presents a new open-source simulator that answers the case of more complex rooms by analysing them using a 3D STL (stereolithography) model. This paper describes this new tool in detail, with the material used, the software architecture, the ray tracing algorithm, and validates it against the literature and presents new use cases. To the best of our knowledge, this simulator is the only free and open-source ray tracing analysis for complex 3D rooms for VLC research. In particular, this simulator is capable of studying any room shape, such as an octagon or an L-shape. The user has the opportunity to control the number of emitters, their orientation, and especially the number of rays emitted and reflected. The final results are detailed heat maps, enabling the visualization of the optical power distribution across any 3D room. This tool is innovative both visually (using 3D models) and mathematically (estimating the coverage of a VLC system). [ABSTRACT FROM AUTHOR]

One of the primary challenges faced by visible light communication (VLC) systems employing optical orthogonal frequency division multiplexing is the peak-to-average power ratio (PAPR). This study is dedicated to designing, simulating, and evaluating bit error rate (BER) and PAPR reduction methods tailored for the VLC broadcasting system. The asymmetric clipped optical orthogonal frequency division multiplexing (ACO-OFDM) scheme is highlighted in this work for its impressive performance. Therefore, the proposed PAPR mitigation methodologies applied to ACO-OFDM. The proposed PAPR reduction strategy involves 5 distinct precoding methodologies. The PAPR was mitigated by 3.485 dB after applying the DST precoding methodology. Still, the WHT precoding methodology can achieve PAPR reduction by 1.131 dB, without BER performance degradation, with respect to the conventional ACO-OFDM system. Furthermore, the work addresses another challenge in VLC systems: the bit error rate (BER). This is accomplished by introducing approaches to Time Domain Noise Cancelation and Frequency Domain Noise Cancelation (FDNC). The BER performance of these 2 receiver models is nearly the same. The simulation results indicate the system performance enhancement after applying noise cancellation approaches by 1.65 dB at the 4-QAM modulation scheme and 2.97 dB at the 1024-QAM modulation scheme. The 16-QAM modulation scheme, after applying DST and WHT methodologies alongside noise cancellation approaches, can enhance both PAPR by 20.83% and 6.76%, but the Eb/N0 performance enhancement by 10.10% and 14.64%, respectively. Additionally, the effectiveness and validity of the proposed schemes are verified by comparing them with relevant literature reviews on PAPR reduction techniques and selecting an optimal choice among them. [ABSTRACT FROM AUTHOR]

With the emergence of cellular networks, the wireless communication network system has evolved from the first generation to the sixth generation (6G), which will provide an integrated framework for a variety of utilities, applications, and technologies. One emerging technology for 6G communication network systems is reconfigurable intelligent surfaces (RIS), which is ideal for smooth and controllable wireless signal transmission. RIS is mainly a programmable structure that can regulate the propagation of electromagnetic waves by smartly tuning a large number of elements via an electronic controller. This study presents a complete overview of RIS, including its hardware architecture, key characteristics, control mechanism, carrier frequency, communication duplex mode, and working procedure. The study also elaborates on the RIS propagation scenarios, advantages of implementing RIS, deployment, and different types of communication by utilizing RIS. Finally, we conclude with a discussion of challenges and future research directions to overcome limitations to achieve the goal of RIS implementation and RIS-aided communication for 6G communication systems. [ABSTRACT FROM AUTHOR]

In this paper, a novel adjustment algorithm of the position-predicted period (PP) in an indoor visible light communication (VLC) network is proposed. The algorithm is adaptive to the movement speed. It contains two key parts: speed-adaptive position information (PI) collection and speed-adaptive PP adjustment. By the user's mobile characteristics, speed-adaptive PI collection is realized to lift prediction accuracy. By distribution characteristics of received power, speed-adaptive PP adjustment is achieved to avoid unnecessary predictions. By the access point (AP) selection, based on position prediction and the PP adjustment algorithm adaptive to movement speed, the user's transmission quality under different movement speeds can be improved. Finally, by simulation, the effectiveness of this algorithm is demonstrated. [ABSTRACT FROM AUTHOR]

Visible light communication (VLC) has the potential of combining the idea of illumination and communication, and that creates the growing interest of using optical communication in recent wireless communication scenario. To any electronic gadgets used by the doctors, the VLC can transfer the medical information through the light emitting diodes (LEDs) installed in the room (indoors) for the purpose of illumination. The broadband transmission technology is supported by VLC. A wireless sensor network (WSN) is a network composed of numerous autonomous sensor nodes that communicate wirelessly to collect and transmit data from the patients. These networks are commonly used in scenarios where it is not practical to use wired communication, or where data need to be collected from remote or inaccessible locations. Cluster nodes reinforcement scheme (CNRS) improves the routing efficiency and also increases the network lifetime. In this scheme, the base station transmits the pilot message to each node, and normal nodes reply back to the pilot message. The work evaluates about end-to-end (ETE) delay of CNRS and BER in binary phase shift keying (BPSK) with DC-biased optical orthogonal frequency division multiplexing (DCO-OFDM) in VLC while transferring the medical details collected through WSN. [ABSTRACT FROM AUTHOR]

Underwater wireless communication stands as a captivating and swiftly progressing domain in recent. To support higher data rate and higher bandwidth applications, there is significant attention towards underwater acoustics along with Visible Light Communication (VLC) technology. Underwater sensor networking serves as the backbone of oceanic exploration efforts. Based on the traffic load and underwater environmental conditions, an appropriate communication link can be selected to achieve higher data rate. Acoustics supports communication over longer distances with lower data rate. Despite offering higher data rates, Visible Light Communication (VLC) faces limitations in terms of communication range, proving to be relatively short compared to other methods. A seamless transition is anticipated during data transmission and reception by employing Light Emitting Diodes (LEDs) and photo detectors on the optical-acoustic channel, bridging the gap between acoustic and optical communication methods. Utilizing MIMO-based Enhanced Reverse Polarity Orthogonal Frequency Division Multiplexing (MIMO-ERPO-OFDM) in Underwater Optical Communication (UWOC) proves to be a superior approach, achieving a high throughput of 19.9 Mbps and a lower Bit Error Rate (BER) of 10− 1. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Qadisiyah Computer Science & Mathematics is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Security postulates of visible light communication (VLC) is a paramount area of consideration due to its deployment in military, businesses, and residential establishments. Optical code division multiplexing (OCDMA) is prominent multiples access technique to serve multiple users and offer better security as compared to other available techniques such as wavelength and time division multiplexing (TDM). Wavelength conversion, multicode keying, optical logic gates, and quantum key distribution are some of the widely used security enhancement techniques but come at high cost and greater complexity. Zero cross correlation codes (ZCC) with integration of time dimension is an ultimate solution to the complex security improvement techniques but conventional two dimensional (2D) ZCC codes has an utmost issue of adjacent weights (W) and time (t) in the code which can be easily decoded by eavesdropper. Therefore, in this work, a novel weight managed ZCC (WMZCC) OCDMA code is presented with the non-adjacent W and t in the code matrix for making authentic information decoding difficult. Proposed 2D-WMZCC codes are investigated for 5 users at 100 Gbps over VLC link length of 5 m using polarization division multiplexed (PDM) quadrature phase shift keying (QPSK) and digital signal processing in terms of log symbol error rate (log SER), Q factor and bit error rate (BER). Further, a detailed comparison of 2D-WMZCC codes is performed with existing 2D diagonal identity matrix (DIM) codes and results revealed that former one exhibits better security than later OCDMA code. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive analysis of a bridged-T equalizer circuit (BTEC) designed for a high-speed visible light communications (VLC) system. The circuit is proposed to overcome the bandwidth limitation of light-emitting diodes (LEDs) in the VLC system. The advanced design system (ADS) and MATLAB were integrated to analyze the behavior of the BTEC in terms of transfer functions and scattering parameters S11, S12, S21, and S22. The results indicate a good correlation between the two tools, with the center frequency being 786 MHz. The 3-dB lower and upper cut-off frequencies are 501 MHz and 1.23 GHz, respectively. The impedance point is at magnitude 1 and 0 phase degrees on the Smith chart. This precise point ensures optimal matching to 50 ? of source and load impedance. This simulation proves that the bridged-T pre-equalizer circuit is a symmetric and reciprocal network since S11 = S22 and S12 = S21. This work combines the computational capabilities of MATLAB with the circuit simulation capabilities of ADS, which satisfied the pre-equalizer circuit experimental stage. ABSTRAK: Kertas kerja ini membentangkan analisis komprehensif bagi litar penyama T terjepit (BTEC) yang direka untuk sistem komunikasi cahaya nampak (VLC) berkelajuan tinggi. Litar ini dicadangkan untuk mengatasi had lebar jalur diod pemancar cahaya (LED) dalam sistem VLC. Sistem reka bentuk lanjutan (ADS) dan MATLAB telah disepadukan untuk menganalisis kelakuan BTEC dari segi fungsi pemindahan dan parameter serakan S11, S12, S21, dan S22. Keputusan menunjukkan korelasi yang baik antara kedua-dua alat, dengan frekuensi tengah ialah 786 MHz. Frekuensi potong bawah dan atas 3-dB ialah 501 MHz dan 1.23 GHz, masing-masing. Titik impedans adalah pada magnitud 1 dan 0 darjah fasa pada carta Smith. Titik tepat ini memastikan padanan optimum kepada 50 ? sumber dan galangan beban. Dalam simulasi ini, terbukti bahawa litar pra-penyamaan bridged-T adalah rangkaian simetri dan timbal balik sejak S11 = S22 dan S12 = S21. Kerja ini menggabungkan keupayaan pengiraan MATLAB dengan keupayaan simulasi litar ADS, yang memenuhi peringkat percubaan litar pra-penyamaan.

【Objective】Light Emitting Diode (LED) is an important nonlinear optical signal generating device in Visible Light Communication (VLC) systems. The static nonlinearity of LED and the dynamic nonlinear memory effect caused by frequency response can lead to signal distortion and degrade the system performance.【Methods】The nonlinearity of LED can usually be compensated by estimating a pre-distortion model, and the wireless VLC is usually intensity modulated/directly detected.【Results】Therefore, the LED nonlinearity modeling is investigated, and an adaptive pre-distortion device based on Amplitude Factorization Polynomial (AFP) is proposed to compensate LED nonlinearity in this paper. Simulation results show that the proposed scheme exhibits good Bit Error Rate (BER), Amplitude Modulation/Amplitude Modulation (AM/AM) correction and constellation diagram performance with higher modeling accuracy.【Conclusion】The normalized mean square error performance improvement of more than 15 dB compared with the traditional memory polynomial is achieved.

Achieving fairness in power allocation is crucial for maximizing the performance of Non-Orthogonal Multiple Access (NOMA) systems in Visible Light Communication (VLC). However, existing power allocation methods for NOMA-VLC often struggle to maintain fairness. This paper addresses this challenge by introducing the Empirical Fair Optical Power Allocation (EFOPA) method. EFOPA leverages a simplified mathematical model to achieve maximum fairness among users, ensuring equitable data rates even when channel conditions and illumination levels vary. Furthermore, EFOPA significantly reduces computational complexity compared to optimisation based approaches, making it suitable for dynamic environments where users move frequently. Simulation results demonstrate that EFOPA outperforms existing methods GRPA and NGDPA in terms of fairness and maintains comparable sum-rate performance, offering a robust and efficient solution for power allocation in NOMA-VLC systems. [ABSTRACT FROM AUTHOR]

In recent years, visible light positioning (VLP) techniques have been gaining popularity in research. Among them, the scheme of using a camera as a receiver provides a low-cost, high-precision positioning capability and easy integration with existing multimedia devices and robots. However, the pose changes of the receiver can lead to image distortion and light displacement, significantly increasing positioning errors. Addressing these errors is crucial for enhancing the accuracy of VLP. Most current solutions rely on gyroscopes or Inertial Measurement Units (IMUs) for error optimization, but these approaches often add complexity and cost to the system. To overcome these limitations, we propose a 3D positioning algorithm based on an attention mechanism convolutional neural network (CNN) aimed at reducing the errors caused by angles. We designed experiments and comparisons within a rotation angle range of ±15 degrees. The results demonstrate that the average error for 2D positioning is within 5.74 cm and the height error is within 3.92 cm, and the average error for 3D positioning is within 6.8 cm. Among the four groups of experiments for 3D positioning, compared to the traditional algorithm, the improvements were 7.931 cm, 15.569 cm, 6.004 cm, and 16.506 cm. The experiments indicate that it can be applied to high-precision visible light positioning for single-light imaging. [ABSTRACT FROM AUTHOR]

In-flight entertainment services can be supported by visible light communication (VLC) technology. Light-emitting diodes (LEDs) can be deployed in the VLC cells within an aircraft cabin to transmit data. It is possible to deploy VLC system within the defined enclosed location to share the information and also to avoid the possibility of eavesdropping and to eradicate interference. VLC supports high data rate access among multiple users inside aircraft cabin. The paper analyses about the VLC system used for transmitting data in the aircraft. The optical transmitter is the fixed reading light unit (LEDs) in each seat. High data rate and better signal-to-noise ratio (SNR) will be offered for each passenger through variable delta sigma modulation (vDSM) method combined with optical orthogonal frequency division multiplexing (OFDM) technique. [ABSTRACT FROM AUTHOR]

The visible light communication (VLC) technology has been gathering attention recently and as the emerging systems and appliances in this technology are still new, their behavior and performance issues must be taken into the consideration as much as possible. This paper aims to fully model the noise that is emanating from the usage of the Single-photon avalanche diodes (SPADs) in the VLC systems. This noise is either modeled with the sub-Poisson or Gaussian plus sub-Poisson distributions. These noise models are then applied to the diffusion adaptive networks to show the real-world impact of the VLC noisy links on their performances. The radio noisy link impacts have been investigated on the performance of the diffusion adaptive networks, however, the effects of the optical link noise on their performances is the contribution of this paper. Also, using the realistic and precise models for the optical noise is another novelty in this paper. The results show that the diffusion network can be implemented using VLC appliances and the existence of the SPAD noise will not hinder the convergence of this network. [ABSTRACT FROM AUTHOR]

Visible light communication (VLC) is becoming more relevant due to the accelerated advancement of optical fibers. Polymer optical fiber (POF) technology appears to be a solution to the growing demand for improved transmission efficiency and high-speed data rates in the visible light range. However, the VLC system requires efficient splitters with low power losses to expand the optical energy capability and boost system performance. To solve this issue, we propose an effective 1 × 8 optical splitter based on multicore polycarbonate (PC) POF technology suitable for functioning in the green-light spectrum at a 530 nm wavelength. The new design is based on replacing 23 air-hole layers with PC layers over the fiber length, while each PC layer length is suitable for the light coupling of the operating wavelength, which allows us to set the right size of each PC layer between the closer PC cores. To achieve the best result, the key geometrical parameters were optimized through RSoft Photonics CAD suite software that utilized the beam propagation method (BPM) and analysis using MATLAB script codes for finding the tolerance ranges that can support device fabrication. The results show that after a light propagation of 2 mm, an equally green light at a 530 nm wavelength is divided into eight channels with very low power losses of 0.18 dB. Additionally, the splitter demonstrates a large bandwidth of 25 nm and stability with a tolerance range of ±8 nm around the operated wavelength, ensuring robust performance even under laser drift conditions. Furthermore, the splitter can function with 80% and above of the input signal power around the operated wavelength, indicating high efficiency. Therefore, the proposed device has a great potential to boost sensing detection applications, such as Raman spectroscopic and bioengineering applications, using the green light. [ABSTRACT FROM AUTHOR]

This paper investigates the performance of dual-hop unmanned aerial vehicle (UAV)-assisted communication channels, employing a decode-and-forward (DF) relay architecture. The system leverages terahertz (THz) communication for the primary hop and visible light communication (VLC) for the secondary hop. We conduct an in-depth analysis by deriving closed-form expressions for the end-to-end (E2E) bit error rate (BER). Additionally, we use a Monte Carlo simulation approach to generate best-fitting curves, validating our analytical expressions. A performance evaluation through BER and outage probability metrics demonstrates the effectiveness of the proposed system. Specifically, our results indicate that the proposed system outperforms Free-Space Optics (FSO)-VLC and Radio-Frequency (RF)-VLC at a higher signal-to-noise ratio (SNR). The results of this study provide valuable insights into the feasibility and limitations of UAV-assisted THz-VLC communication systems. [ABSTRACT FROM AUTHOR]

Automatic Modulation Format Identification(AMFI) is an important issue in Visible Light Communication (VLC). There are several factors that affect the performance of vehicular VLC (V-VLC) systems. To accomplish the required communication quality for different traffic scenarios, It needs adaptive modulation techniques. Adaptive modulation requires modulation format identification at the receiver to avoid the overhead required to determine the proper modulation format. In this paper, we propose an AMFI scheme based on Deep Learning (DL) for Infrastructure-to-Vehicle (I2V) VLC. Our scheme utilizes the Hough transform to project the constellation diagram of the received modulated signals onto another space to extract features efficiently. Hough transform is estimated for eight different VLC modulation formats, including Q/8/16-Phase Shift Keying (PSK) and 4/16/32/64-Quadrature Amplitude Modulation (QAM) at signal to noise ratio (SNR) ranging from 5 to 25 dB. Conventional classifiers such as Alexnet, Sequeeznet and Googlenet are used to perform the task of AMFI. A study of the impact of the weather conditions and the communication distance on the accuracy of the used classifiers is introduced. The obtained results prove that the proposed scheme can identify the modulation format with high classification accuracy up to 100% at lower SNR levels and different weather conditions. [ABSTRACT FROM AUTHOR]

In modern homes, the home automation is more preferable to ensure safety and security. Lots of devices can be interconnected in home automation through wireless technologies. The overhead of data communication increases with increasing data transmission through local wireless network like wireless fidelity from the devices used in indoors. Spatial reprocess is not able to meet the current needs with accumulative traffic demand in existing communication technique. The paper focuses the need of visible light communication in future era in home automation system. The sustainable materials in light emitting diodes requires less power than normal forms of lightning. It consumes less energy and impacts positive effect in the environment. Also it has reduced emission effect and supports eco-friendly environment. The proposed work is the usage of Light Fidelity (Li-Fi) with unipolar OFDM (DC biased Optical OFDM (DCO-OFDM)) method to support data transmission with enhanced Signal to Noise Ratio (SNR), data rate and reduced Bit Error Rate (BER) in the home automation system. [ABSTRACT FROM AUTHOR]

【Objective】The non-linear characteristics of Light Emitting Diodes (LEDs) contribute to the degradation of Bit Error Rate (BER) performance in Visible Light Communication (VLC) systems, particularly in Optical Orthogonal Frequency Division Multiplexing (O-OFDM) systems with high Peak-to-Average Power Ratio (PAPR). A single-stage equalizer based on the Volterra series can handle the high-order non-linear distortions of LEDs with low latency. However, solving the traditional Volterra series necessitates multiple integration operations, resulting in the high implementation complexity of the Volterra-based equalizer. Additionally, the single-stage equalizer accumulates errors with limited performance improvements.【Methods】Firstly, to address the issue of high computational complexity in the traditional calculations of the Volterra series, a proposition is made to retain only the high-order power series terms of the various nonlinear terms and kernel coefficients within the Volterra series. This approach, known as the Memory Polynomial-based Volterra Series (MPVS), not only reduces the computational complexity compared to the traditional Volterra series but also enhances the accuracy of nonlinear system modeling by considering all input signals at the current moment. Subsequently, the design of channel equalizer considers the Memory Polynomial-based Volterra (MPV) equalizer and the Memory Polynomial-based Volterra Decision Feedback Equalizer (MPV-DFE). For a single-stage MPV-DFE, if an error occurs in the decision part leading to an incorrect symbol decoding, this error tends to manifest as a consecutive series of errors, thereby impacting the entire symbol sequence. To mitigate this, a proposal is made to cascade the two non-linear equalizers, MPV and MPV-DFE, forming a hybrid equalizer called MPV+MPV-DFE. The MPV equalizer performs a primary equalization on the LED's nonlinear distortion signal, effectively suppressing a portion of the non-linear distortions and thereby reducing symbol decoding errors in the MPV-DFE. Subsequently, a secondary equalization is carried out by the MPV-DFE, leading to improved suppression of residual nonlinear distortions.【Results】Finally, the effectiveness of the system design was validated using Monte Carlo simulation to analyze the BER. The results demonstrate that compared to the single-stage MPV equalizer and the linear-cascade nonlinear hybrid equalizer (LMS+MPV-DFE), the proposed hybrid equalizer achieves approximately 7 dB and 2 dB Signal-to-Noise Ratio (SNR) gains, respectively, in a 4 Quadrature Amplitude Modulation (QAM) -modulated Asymmetrically Clipped Optical OFDM (ACO-OFDM) system at a BER of 10-4.【Conclusion】In conclusion, the implementation of the MPV equalizer is straightforward, and the cascaded design of the two-stage nonlinear equalizers as a hybrid equalizer enables better mitigation of the LED’s nonlinearity.

The ever-growing demand for speed and bandwidth in data-centric applications necessitates innovative solutions to overcome existing bottlenecks. Traditional data centers reliant on electronic infrastructure often face limitations in speed. While the concept of optical data centers has emerged as a promising alternative, the practical implementation has been hindered by component unavailability, such as tunable wavelength converters and optical memory. Furthermore, the transition to fiber optic technology has not fully addressed issues like heat dissipation associated with copper cables. To address these challenges, the utilization of visible light communication (VLC) within an optical wireless medium has been proposed, aiming to reduce cabling complexities and mitigate heat generation. This paper presents a comprehensive design and analysis of a VLC-enabled optical wireless data center, leveraging Filter Bank Multicarrier (FBMC) modulation. Key considerations including peak-to-average power ratio, bit error rate and error vector magnitude are thoroughly examined, accompanied by the derivation of relevant mathematical models and presentation of simulation results. Through the integration of VLC-FBMC technology, this research contributes to the advancement of efficient and high-speed data center architectures, promising enhanced performance and scalability for future data-intensive applications. [ABSTRACT FROM AUTHOR]

Copyright of Study on Optical Communications / Guangtongxin Yanjiu is the property of Study on Optical Communications Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Visible Light Communication (VLC) systems are favoured for numerous applications due to their extensive bandwidth and resilience to electromagnetic interference. This study delineates various constructions of Optical Orthogonal Frequency Division Multiplexing (O-OFDM) approaches employed in VLC systems. Various factors are elaborated within this context to ascertain a more effective O-OFDM approach, including constellation size, data arrangement and spectral efficiency, power efficiency, computational complexity, bit error rate (BER), and peak-to-average power ratio (PAPR). This paper seeks to assess these approaches' BER and PAPR performance across varying modulation orders. Regrettably, in VLC systems based on OFDM methodology, the superposition of multiple subcarriers results in a high PAPR. Therefore, this study aims to diminish the PAPR in VLC systems, enhancing system performance. We propose a non-distorting PAPR reduction technique, namely the Vandermonde-Like Matrix (VLM) precoding technique. The suggested technique is implemented across various O-OFDM approaches, including DCO-OFDM, ADO-OFDM, ACO-OFDM, FLIP-OFDM, ASCO-OFDM, and LACO-OFDM. Notably, this method does not affect the system's data rate because it does not require the mandatory transmission of side information. Furthermore, this technique can decrease the PAPR without impacting the system's BER performance. This study compares the proposed PAPR reduction technique against established methods documented in the literature to evaluate their efficacy and validity rigorously. [ABSTRACT FROM AUTHOR]

Visible light communication (VLC) becomes an interesting technology for next-generation networks due to its wide license-free spectrum. However, the limited modulation bandwidth of the light sources remains a challenge for VLC networks. To address this issue, a new architecture that combines both non-orthogonal multiple access (NOMA) and filter bank multicarrier communication (FBMC) is suggested in this paper to improve spectrum efficiency in VLC networks. However, this enhancement comes with the drawback of a high peak-to-average power ratio (PAPR). Therefore, this paper also proposes a three-layer hybrid PAPR reduction method based on integrating amplitude clipping (AC) and selective mapping (SLM) techniques with Lifting Wavelet Transform (LWT). The proposed method improves both the bit error rate (BER) and PAPR performances of the NOMA based FBMC-VLC network. Applying the proposed PAPR reduction method to the NOMA-based FBMC-VLC architecture achieve a notable enhancement in throughput while simultaneously improving both PAPR and BER performances. The results demonstrate a notable increase in network throughput, with gains of 9 b/s/Hz and 2 b/s/Hz in comparison to conventional FBMC and the system outlined in Hesham and Ismail (Opt Quant Electron 54:201, 2022), respectively. Furthermore, both PAPR and BER performances exhibit satisfactory improvements of 7.75 dB and 10 dB, respectively, following the application of the proposed hybrid PAPR reduction method. [ABSTRACT FROM AUTHOR]

DC-biased optical OFDM (DCO-OFDM) is a commonly used method of OFDM in visible light communication (VLC). Unfortunately, VLC systems that use OFDM often experience a high peak-to-average power ratio (PAPR). To address this issue, this study proposes a novel method called the multi-point constellation method (MPC) to reduce PAPR in DCO-OFDM. The MPC method involves adding extra alternative constellation points around the existing points and using the discrete particle swarm optimization (DPSO) algorithm to select the constellation points with the lowest PAPR. The proposed MPC method is also combined with selective mapping (SLM), a well-known PAPR reduction technique in the literature. Simulation results show that the proposed MPC method outperforms the SLM method in reducing PAPR in 4-QAM and 16-QAM modulations when used in combination with SLM. Furthermore, increasing the number of iterations and particles in the DPSO algorithm improves the PAPR reduction performance of the proposed method even further. [ABSTRACT FROM AUTHOR]

In this article, Intelligent Reflecting Surfaces (IRS) are used for Non Orthogonal Multiple Access (NOMA) in hybrid Radio Frequency (RF) Visible Light Communications (VLC). The source broadcasts the symbols of K users. The broadcasted signal by the source is reflected by IRS on RF link to reach the relay node R with the same phase. Relay node detects the symbols of K users using Interference Cancelation (IC). Then, relay nodes broadcasts the symbols of K users on VLC link. We show that NOMA using IRS for hybrid RF/VLC offers 12–18 dB gain versus conventional hybrid RF/VLC without reflectors for N = 32 ,168 reflectors. The main advantage of the paper is to enhance the throughput of RF/VLC systems using IRS. The main limitation of the paper is that the results are not valid when energy harvesting is performed. [ABSTRACT FROM AUTHOR]

Light emitting diode (LED) non-linearities bounds the output performance of visible light communication (VLC) system. LED's front-end components and high peak to average power ratio (PAPR) of the transmitted signal are the main contributors of distortion in transmitted signal. In this work, both pre-distortion and post-distortion techniques are analyzed for the reduction of non-linear distortion of intensity modulation/direct detection (IM/DD) based channel. The modulation technique used is (OQAM-O-FBMC) offset quadrature amplitude modulation optical filter bank multi-carrier. A hybrid PAPR reduction and non-linear distortion mitigation technique for VLC is proposed. The proposed technique consists of hybrid processing algorithm partial transmit sequence (H-PTS) method for PAPR reduction and kernel minimum symbol error rate (KMSER) based post-distortion method for reduction of non-linear distortion. MATLAB based simulations have been provided for the analysis of proposed hybrid method. The results have shown that proposed hybrid technique shows 2 dB improvement in PAPR and 4 dB improvement in non-linear distortion of VLC system. [ABSTRACT FROM AUTHOR]

Future wireless networks are researching how to fulfill the growing demand for wireless optical communication. The increased usage of mobile devices and sensors in the real world has resulted in this increasing demand. The fifth-generation (5G) wireless network is the most promising wireless network in the future, with the potential to improve various performance metrics such as spectrum and energy efficiency, high capacity, and low latency. Orthogonal frequency division multiplexing (OFDM) can be produced using cyclic prefix and Fast Fourier Transforms to fight extreme multipath fading. Filtered OFDM, such as Filter-Bank Multi-Carrier (FBMC), can be used to circumvent this limitation. The usage of FBMC to improve the performance of 5G networks is discussed in this paper, along with several hot issues like visible light communication, cognitive radio, and multiple-input multiple-output that FBMC may be utilized with to improve communication. [ABSTRACT FROM AUTHOR]

There will be adverse effects on human health while the exposure of Radio frequency (RF) waves is long term in the indoor environment. The old age people, children's and patients will be badly affected, if their immune system is weak. In such environment, the visible light communication (VLC) is the preferred communication technique which provides immunity towards the adverse effects by RF. Presently the fluorescent lamps were replaced by light-emitting diodes (LEDs) in the indoor environment. The practice of utilizing the LEDs have been penetrated in many areas in our day to day life. The device will provide lightning capabilities and also information broadcast. In VLC for the purpose of data transmission and reception, the LED light source and photodetector (PD) were used. The work presents about VLC channel model, LED characteristics, data transmission model (RPO-OFDM-vDSM model) in indoors which provides better spectral efficiency and data rate. [ABSTRACT FROM AUTHOR]

The Sixth Generation (6G) Wireless Communication Network (WCN) is the successive provision to ameliorate the gain with ultra-low latency, and e xtremely high energy efficiency. The 6G WCN enables the specifications of artificial intelligence to optimize the services and capabilities. The vision of the 6G era is expected to address a seamless fusion of communication between the human, physical world, and digital world. The latest 6G WCN standard is a fundamental foundation and requires immense attention in the field of research. This paper presents the framework of 6G WCN with an illustration of its key technologies. The different technologies involved in 6G are well explained with the demonstration of the communication scenario such that the key performance indicators are improved with major differences. The primary contribution of this paper is the explanation of the 6G with the technologies that have a drastic impact on the characteristic aspects of a wireless communication network such as data rate, spectrum efficiency, energy efficiency, connection density, and reliability. All these technologies have the capability to revolutionize the subsequent WCN.

This paper combines the advantages of both cognitive radio (CR) and visible light communication (VLC) for car-to-car applications to achieve a high data rate with minimum (delay, outage probability, bit error rate (BER), and cost). CR technology hops among the existing radio frequency (RF) available channels to increase the RF spectrum usage efficiency and dodge the scarcity limitation. Moreover, using CR as a license-free application will reduce car-to-car communication running costs. However, CRs require a common control channel (CCC) to communicate the spectrum availability map within the CR network and to inform the receiver end about the change in the transmitter-end channel. Therefore, the CCC is the bottleneck in the car-to-car CR network. Then, we explore the types of CCCs and discuss using each of them to solve this bottleneck issue. In the proposed scheme, we adopt using VLC as CCC. A MATLAB simulation for a car-to-car framework is built to demonstrate the capabilities of VLC through the chosen metrics (i.e., data rate, delay, outage probability, cost, and bit error rate). Our results show that VLC achieves up to 90% of the licensed data rate with a small outage probability of 21.2% and moderate BER and delay. In addition, VLC presents the minimum cost, placing second after the licensed type with a score of 84.2% in the combined metric. In conclusion, with the VLC’s bright future of expansion and growth in the car-to-car application, we have proven that VLC is worthy of implementation practically in modern cars.

Orthogonal frequency division multiplexing (OFDM) is critical for high-speed visible light communication (VLC) transmission; however, it suffers from a high peak-to-average power ratio (PAPR) problem. Among PAPR reduction techniques, pre-coding methods have shown promising advantages such as signal independence and no requirement for signaling overhead. This paper introduces a novel pre-coding technique termed quartered composite transform pre-coding (QCTP), which employs four newly developed orthogonal pre-coding matrices applied to four equally divided segments of modulated data, thereby enhancing the PAPR performance of VLC systems utilizing OFDM. This methodology allows the utilization of a single-tap equalizer, achieving over a 6 dB reduction in PAPR compared to conventional DCT pre-coding and surpassing the PAPR performance of DCT-hybridized (DCT & $\mu $ -compounding and DCT & Gaussian matrix) pre-coding techniques. This enhancement is accomplished without compromising bit error rate (BER) performance, all while maintaining reduced complexity.

As industrial communication continues to evolve to increase flexibility through wireless communication, networked optical wireless communication (OWC), also known as LiFi, has emerged as a promising candidate technology due to its unlicensed spectrum and relatively deterministic propagation. The inherent containment of light improves security, enables dense cellular networks with spatial reuse, and results in reduced sporadic interference while providing high-capacity short range communication links to mobile end devices. This paper outlines the features of the new IEEE Std 802.15.13-2013, suitable for industrial OWC, and presents details of our prototype implementation along with initial experiments. The standard specifies deterministic medium access control (MAC), based on dynamic time division multiple access (TDMA), as well as two physical layers (PHYs) for extended range and robustness, and for spectral efficiency, respectively. Our prototype includes a central coordinator, implemented entirely in software, running on commodity server hardware. It connects to distributed ceiling-mounted optical wireless frontends via a packet-switched network (Ethernet) and is capable of forming them into adaptive virtual cells on a per-user basis. This approach enhances reliability through multiple-input multiple-output (MIMO) transmission and allows for smooth mobility. We implemented the Pulsed Modulation PHY (PM-PHY) on a commercially available field programmable gate array (FPGA) evaluation board. Initial test results indicate that the PM-PHY supports typical distances of up to 6 m between the ceiling and the mobile device. The MAC achieves deterministic latency values below 4 ms.