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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]

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]

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]

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]

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]

To overcome the multi-path effect in Visible Light Communication (VLC) Quasi-Synchronous (QS) Optical Code Division Multiple Access (OCDMA) system, Optical Zero Correlation Zone (OZCZ) code set pair have been proposed. In this article, new two methods for constructing OZCZ codes based on the Double Weight (DW) and the Zero Cross Correlation (ZCC) matrix are presented. The newly proposed methods are based on ZCC constructions that allow generating code sequences having all ZCC and OZCZ properties, ideal for use in VLC-QS-OCDMA transmission. The structure of the proposed ZCC-OZCZ code is simple, less complex, and their construction is more flexible than proposed DW-OZCZ and existing construction. In addition, the performance evaluation of the system adopting the proposed constructions, in terms of Bit Error Rate (BER), show that the proposed codes significantly reduce MAI compared to ZCC, and give the same performance as unipolar OZCZ codes with more simple and flexible construction. [ABSTRACT FROM AUTHOR]

In the present scenario, there is a boom in the demand of the users to achieve increased capacity, high data, low latency, and high-performance rates. 5G New Radio deals with a frequency band in millimeter range in GHz, but our agenda is to go beyond the frequency range in THz, which can be attained through Visible Light Communication (VLC). 5G NR no doubt works on high evolution and reliability but faces a severe issue of harmful radiations from its high-frequency electromagnetic waves risking human health. Thus, there is an urgent need to shift from the current RF technology towards the pragmatic approach reliable in fulfilling all the parameters such as low power consumption, more energy-efficient, high data rate, low latency and has wider spectral efficiency and provides better quality of service (QoS) and high security. In this paper, we design a mathematical model experiencing reflection from multiple reflectors. An architecture with the prime motive of enhancing the signal strength is adopted using various techniques such as adaptive beam swapping, Bragg grating, and hybrid access technology (RF + VLC). In this paper, we have done a comprehensive survey of VLC and proposed new techniques to enhance the same. Here, we are considering VLC for an indoor area where the user is in LOS of the VLC router. Reduction in the carbon footprint and progressing towards green communication is our social responsibility. The main component used in VLC is the Led and a photodiode at the transmitter and the receiver end, respectively. Led is used as it is much energy-efficient, durable, and easy to install and radiates no harmful radiation; thus has no ill effect on human health. This survey will play a vital role in B5G/6G network. [ABSTRACT FROM AUTHOR]

In this paper, we suggest the use of Reconfigurable Intelligent Surfaces (RIS) for hybrid Radio Frequency (RF) Visible Light Communications (VLC). The signal is transmitted from a transmitter T to a relay C using RIS. RIS is implemented as a transmitter or a reflector between T and C. The relay node C decodes the received signal and transmits it to the receiver R using a VLC link. The proposed VLC/RF communications using RIS offers 20–45 dB gain with respect to conventional RF/VLC when the number of reflectors N is varied from N = 16 to N = 256 . [ABSTRACT FROM AUTHOR]

In this paper, visible light communication (VLC) link was setup using electronic components commercially available which can achieve a data rate up to 2.55 Mb/s and link range of 80 cm. Generally, VLC link setup for high data rates and long-range communication uses modified LEDs and photodiodes. One of such modification is to enhance modulation bandwidth to increase data rate but it limits the luminosity of LED to be used for lighting, also such modified LEDs are not available for commercial use. The main idea of this research is to setup a VLC link using common commercially available LEDs to integrate lightning and communication to reduce cost and achieve high data rate and long-range communication. In this work, red, white and yellow LEDs are used at transmitter as source with two different LED driver to drive LED to transmit binary data 1's and 0's. At receiver BPW34, S1227-66BQ and NRC-815 photodiodes are used based on cost and minimum response time to receive data. In this work different combination of electronic component are tested and results are compared in terms of frequencies versus intensity and rise time to achieve a goal of high data rate and long-range communication. [ABSTRACT FROM AUTHOR]

Today's access networks are in high demand to fulfill the high bandwidth requirement because of extensive improvement in high transmission rate applications for cloud computing, big data analytics, and other next-generation 5G smart applications. In this work, the symmetrical and bidirectional time and wavelength division multiplexing-passive optical network (TWDM-PON) system is proposed and demonstrated. Orthogonal frequency division multiplexing (OFDM) with 4-level quadrature amplitude modulation is used for downstream and upstream transmission. Also, 625 nm red light-emitting diode is utilized for visible light communication (VLC) using a wireless link to encourage the economic high transmission rate fiber/VLC optical network. The TWDM-PON employing OFDM with the VLC system has been analysed for downstream and upstream channels for variable fiber-wireless link range. Additionally, the impact of a high transmission rate and usage of digital signal processing (DSP) unit to reduce losses due to fiber nonlinearity effects in the proposed link has been investigated. The results show that the maximum faithful wireless and wired range for the proposed system is 140 m and 60 km respectively at 20 Gbps to attain the minimum 3.8 × 10−3 BER. The decrease in error vector magnitude (EVM%) by almost 52% with the use of DSP in the proposed system provides a high transmission rate of 200 Gbps in the proposed link. Further, comparative performance of the proposed system with previous latest works in literature reveals a superior performance of the proposed link. The proposed TWDM-PON system provides a next-generation access network from rural areas to urban areas. [ABSTRACT FROM AUTHOR]

From last few years indoor localization has become more popular for wireless devices. The major reason for its popularity is to access current location efficiently. On the other side visible light communication is attaining interest of researchers due to high growth of wireless communication and solid state lighting. This network structure can produce high accuracy for the resident positioning electromagnetic environment. The proposed approach is viable for both air and underwater communication based on the visible light spectrum. We evaluate the technique for other supervised machine learning algorithms to analyse an accuracy, error distance and computational time for indoor localization in visible light communication network. Experimental work was made by using star topology supported by visible personal area network system based simulator, which corresponds an attribute of PHY and MAC layer for IEEE 802.15.7 standard designed for short range optical wireless communication. The evaluation was carried out for an accuracy, error distance and computational time. The results show that the suggested methodology achieves overall computational accuracy and deliver an acceptable location estimation error. [ABSTRACT FROM AUTHOR]

Filter bank multicarrier (FBMC) modulation scheme has come out as a capable contender for next generation wireless systems. This paper proposes FBMC modulation schemes for visible light communication (VLC). These modulation schemes consist of intensity modulation/direct detection (IM/DD) channel. The objective is to overcome some of the drawbacks of mostly used orthogonal frequency division multiplexing (OFDM) based schemes. Single carrier modulation technique such as multi-level pulse amplitude (M-PAM) and multi-level quadrature amplitude modulation (M-QAM) as multi carrier modulation technique are used to implement FBMC modulation scheme. Both DC bias and non-DC bias methods are used for analysis. The analytical performance is provided using parameters Bit error rate (BER) and spectral efficiency. It is found that proposed FBMC based schemes are more spectral and power efficient than optical OFDM based schemes. [ABSTRACT FROM AUTHOR]

The present paper investigates the impact of three radiation patterns of LED namely Lambertian, Batwing, Elliptical on the BER performance of 4 × 4 indoor multiple-input multiple-output (MIMO) visible light communication (VLC) system. The BER simulation has been done using LOS and LOS plus first reflection (L-R1) signals for ceiling-mounted and wall-mounted LEDs. For the case of ceiling-mounted LEDs, impulse response and BER have been computed using those radiation patterns at the centre and corner of a room (5 m × 5 m × 3 m). It has been found that LED having Elliptical radiation profile is more suitable for LOS signal when receiver is placed at the centre position whereas, Batwing radiation is suitable for L-R1 signal, both at the centre and corner positions. In the case of wall-mounted LEDs, impulse response and BER have been determined at the centre of the room using LOS and L-R1 signals. The results show that Batwing has least BER using LOS signal due to its wide radiation beam, but for L-R1 signal, the Elliptical profile having its narrow radiation beam has provided better BER performance. The present study shows that the BER in MIMO-VLC system not only depends on the transmitter and receiver position but also on the radiation patterns of LED and higher order reflection signals. [ABSTRACT FROM AUTHOR]

Visible light communication (VLC) is suitable and natural candidate for vehicular communication. This paper presents the vehicle to vehicle communication system based on VLC technology utilizing light emitting diodes (LEDs) as a transmitter and photodiode as a receiver. The LEDs are present everywhere in outdoor and vehicles utilizing those for communication. Vehicular ad hoc networks are facilitated by empowering enormous applications to require both proficient and reliable data delivery. Low-latency, simple and cost-effective system is designed with less complexity and high consistency by employing off-the-shelf LEDs and photodiodes which mitigates the implementation of complex protocols of typical wireless communication systems. The signal is transmitted from one vehicle that will be received by another vehicle to make sensible steps and to maintain strategic distance to avoid accidents. In this paper, the performance analysis of VLC based vehicle to vehicle communication (V2V) is presented. The results show that 3.5 Mbps and 500 kbps of data rates have been achieved over the distance of 0.5 and 15 m respectively. Amplitude shift keying, frequency shift keying (FSK) and phase shift keying schemes are tested with non-return-zero coding scheme. Bit error rate, received optical power and received signal voltages are measured and analyzed in this paper for V2V communication. The FSK modulation is an efficient technique for long distance as it has lower losses compared to other techniques. Warning messages are displayed on liquid crystal display. The prototype is evaluated experimentally over the distance of 15 m using an array of LEDs to reduce the chances of accidents. Bit error rate of 10−11 for FSK modulation has been achieved with the signal to noise ratio value of 13 dB in this work. The results confirmed the performance of the proposed system and presented that VLC is a feasible technology for vehicular communication. [ABSTRACT FROM AUTHOR]

One of the areas in which wireless networks based on visible light communication (VLC) are considered superior to traditional radio-based communication is security. The common slogan summarizing VLC security features is: WYSIWYS-'What You See Is What You Send'. However, especially in the case of infrastructure downlink communication, security with respect to data snooping, jamming and modification must be carefully provided for. This paper examines the physical layer aspects of VLC networks with respect to possible disruptions caused by rogue transmitters. We present the theoretical system model that we use in simulations to evaluate various rogue transmission scenarios in a typical indoor environment. We use estimated bit error rate as a measure of the effectiveness of jamming and rogue data transmission. We find that it is quite easy to disrupt, and in some cases to even hijack legitimate transmission. [ABSTRACT FROM AUTHOR]

Orthogonal frequency division multiplexing (OFDM) technique has been widely used in visible light communications (VLC) system (VLC-OFDM). To minimize the performance degradation of VLC-OFDM system caused by high peak-to-average power ratio (PAPR), we propose a SFLAHC-PTS technique to reduce the PAPR of signal in this paper. The proposed SFLAHC-PTS is an improved PTS technique which takes advantages of shuffled frog leaping algorithm and hill-climbing algorithm to optimize conventional PTS technique, reducing the computational complexity of conventional PTS technique. We compare SFLAHC-PTS technique with other PTS techniques on the CCDF performance, as well as computational amount to analyze the superiority of SFLAHC-PTS technique. The results show that the proposed technique can greatly reduce the computational load of conventional PTS technique and has better performance in reducing PAPR than GA-PTS, SFLA-PTS technique. [ABSTRACT FROM AUTHOR]

With the advent of high efficacy light emitting diode directional lamps as a key component in focal lighting, new possibilities emerge for re-designing the smart home scenario. A smart home scenario is characterized by enabled intelligent interworking of various wireless and wired technologies to provide inhabitants with ease of use of appliances, while creating a personalized and safe ambience space. More and more high and low data rate circulates within the indoor ambient space (e.g., home, hospitals, offices). Although, unlicensed technologies, such as wireless local area networks can take upon part of the indoor traffic, the ever increasing demand for such data, and users, calls for either use of licensed or novel unlicensed wireless communication technologies as part of the smart home enablers. This paper focuses on the potentials of visible light communications (VLCs), jointly with radio and fiber communications, to support very dense low and high data rate connectivity, while enabling deployment of secure-sensitive indoor applications, including indoor tracking and localization. The paper proposes a scenario for integrating VLC into the smart home scenario and a conceptual supporting architecture for its deployment. Further, the technical challenges and possible roadmap for the actual deployment are analyzed for the particular case of an eHealth scenario where the utilization of VLC technology is the enabler of the cost-efficient rollout of the required infrastructure and thus the game-changer in a multi-billion eHealth niche that is seeking for cost affordable solutions. [ABSTRACT FROM AUTHOR]

In this paper, various aspects of a color-space-based visible-light communication (VLC) system design are explored, including feasible light color spaces, potential constellation diagrams, data-to-light intensity mapping, and light intensity-to-data demapping. After describing the proposed VLC system and parameters essential for a color-space-based VLC system design, numerous methods of constellation design for generating a target color in a light color space are presented. The proposed method also incorporates a technique to calculate light intensity from the constellation point. The performance of a proposed system is analyzed with an additive white Gaussian noise channel along with various color scenarios. We also investigate two cases to obtain the target color information at the receiver. Simulation results are presented in order to evaluate the performance of the proposed VLC system. [ABSTRACT FROM AUTHOR]