Conference Paper

Light fidelity (Li-Fi): Towards all-optical networking

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Abstract

Motivated by the looming radio frequency (RF) spectrum crisis, this paper aims at demonstrating that optical wireless communication (OWC) has now reached a state where it can demonstrate that it is a viable and matured solution to this fundamental problem. In particular, for indoor communications where most mobile data traffic is consumed, light fidelity (Li-Fi) which is related to visible light communication (VLC) offers many key advantages, and effective solutions to the issues that have been posed in the last decade. This paper discusses all key component technologies required to realize optical cellular communication systems referred to here as optical attocell networks. Optical attocells are the next step in the progression towards ever smaller cells, a progression which is known to be the most significant contributor to the improvements in network spectral efficiencies in RF wireless networks.

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... In some studies, all users or objects were connected to the Li-Fi network. The rest of the users or objects that were outside the network were then transferred to the Wi-Fi network and connected [4]. This type of APS method will not work with the fact that the required data transfer rate may vary with objects or users. ...
... Fidelity has two meanings: one refers to loyalty and the other refers to match and similarity, where the second meaning is used in electronic science. This match means that the output of a signal is consistent with the input and not subject to change and destruction [4]. ...
... The word wireless can be used for anything, say; Bluetooth technology is a wireless connection, so one can communicate without the need for wires. This means that one can transmit information needless of a wire [4,5]. In actual real-world case studies, Li Fi technology has been able to send data at speeds of 1 Gbit / s, which is up to 100 times more popular than conventional Wi-Fi and up to 10 times faster than fiber optic. ...
Article
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With the expansion in the use of IoT, increasing the efficiency of these networks has become even more significant. Objects need reliable communications at suitable speed to be able to reach the expected performance. In a heterogeneous network of IoT, the objects can include users and related devices. Despite the hybrid Li-Fi and Wi-Fi networks, IoT needs were somewhat met. However, the efficiency of these networks depends on the choice of access points at the network level. In this study, a new algorithm was proposed based on the access point selection model, considering the strategic behavior of the objects and users. In this algorithm, inspired by access point selection model, a new adaptive algorithm was selected by choosing the access point by Markov game to enhance the load balancing and efficiency in IoT networks based on Wi-Fi and Li-Fi combination. According to the simulation results, it is seen that the proposed method could greatly increase the efficiency of IoT network and better distributes network load between access points with different technology. Overall network throughput was estimated at an average of at least 10% compared to the load-balancing method with fuzzy logic approach proposed in before research.
... The currently available radio spectrum is below 10 GHz (cm-wave communication), which is insufficient to deal with the demands arising out of these mounting changes and is thus put under severe strain. To deal with this constraint, the wireless communication industry is forced to explore alternative options that are beyond the range of radio spectrum, in particular infrared and visible light spectrums (Tsonev, Videv & Haas, 2013). ...
... Previously, AGV were connected via Wi-Fi communication technologies with the vehicle for route administration or any other control systems. Putting aside the sustainability aspects of wireless data services over radio frequency, the issue still exists in relation to multiple parallel participants in a radio-based network can interfere and alter the reliability of the existent data links (Tsonev et al., 2013). Further, Wi-Fi penetration across walls poses a network security threat. ...
... Furthermore, spatial reuse and co-channel interference are not ideal for automated solutions, especially while controlling AGV. This presents itself as a huge challenge for the wireless communication industry, thus creating an urgency to explore alternative parts of the electromagnetic spectrum which can be used to reduce strain on the already overcrowded RF spectrum (Tsonev et al., 2013). ...
Article
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The overarching aim was to reduce the frequency of connection failures that occur due to the connection speed and reliability, and identify, characterise and optimise the key process input variables (KPIVs). An experimental research approach with an inbuilt planned manipulation to one or more variables in the experimental data set was adopted. Key elements of the Six-Sigma methodology were applied to resolve the issue of high failures due to connection speed and reliability between two Li-Fi transceivers. KPIVs were successfully identified, characterised and optimised to implement a permanent corrective action to ensure a reduction in connection failures from 17% to 0%. The alignment between two Li-Fi transceivers along with Li-Fi cut-out was found to be critical in achieving good connection speed and reliability. The interference due to ambient visible spectrum lighting found to be statistically insignificant. This study explored the application and benefits of accessible wireless data communication technologies. Moreover, it sheds light on the probable factors that may influence Li-Fi connection speed and areas for future research. The current research provides a Six-Sigma based solution to high connection failure rates while using an infrared-based Li-Fi transceiver. Results also offer insights into the analytical tools that were found to be effective during the problem-solving process.
... A number of different research outputs on OWC technology has been presented either for integration with existing technologies or for operating purely on OWC technological competence. Tsonev et al. [4] presented the development of light-fidelity (Li-Fi) systems to be incorporated in cellular networks using orthogonal frequency division multiplexing (OFDM). Potential uplink schemes that could be utilized for these systems were also discussed. ...
... One of the solutions that have been proposed with an aim to complement the conventional RF wireless communication systems is to explore other frequency bands in the electromagnetic spectrum, specifically the visible light band. This shift has led to the discovery of a potential and favorable wireless communication technique commonly referred to as VLC [4,22,44]. This technique is anticipated to reduce a huge amount of traffic on the conventional wireless RF technology which is heavily congested. ...
... Such technologies include RF mobile networks, RF WLANs, and PowerLANs. Relatively, it is explored as an augmentation of these existing technologies [4,5,15,20,21,23,44,50,51]. VLC offers an extra data layer at higher rates in diverse network environments. ...
Article
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With the advancement of solid-state devices for lighting, illumination is on the verge of being completely restructured. This revolution comes with numerous advantages and viable opportunities that can transform the world of wireless communications for the better. Solid-state LEDs are rapidly replacing the contemporary incandescent and fluorescent lamps. In addition to their high energy efficiency, LEDs are desirable for their low heat generation, long lifespan, and their capability to switch on and off at an extremely high rate. The ability of switching between different levels of luminous intensity at such a rate has enabled the inception of a new communication technology referred to as visible light communication (VLC). With this technology, the LED lamps are additionally being used for data transmission. This paper provides a tutorial and a survey of VLC in terms of the design, development, and evaluation techniques as well as current challenges and their envisioned solutions. The focus of this paper is mainly directed towards an indoor setup. An overview of VLC, theory of illumination, system receivers, system architecture, and ongoing developments are provided. We further provide some baseline simulation results to give a technical background on the performance of VLC systems. Moreover, we provide the potential of incorporating VLC techniques in the current and upcoming technologies such as fifth-generation (5G), beyond fifth-generation (B5G) wireless communication trends including sixth-generation (6G), and intelligent reflective surfaces (IRSs) among others.
... Li-Fi Technology is one of the exploring fields that enhances the power of data communication and inter-networks [50]. Li-Fi technology, proposed by the German physicist Harald Haas, researched that transmission of data through illumination by sending data through an LED light bulb [51]. ...
... -33): VQM value vs video frames at 50ᵒ.It is noted that the values of VQM have the values (0) until the frames sequence reached to the frame of(50). Where the change in video of the video sent from the left of the LOS is appear, this means that the distortion in the video of the frames (0-50) did not appear because the heat or hot air current did not effect for these frames. ...
Thesis
Due to the growing in the field of communications to increase bandwidth data, there are need two possible ways to behave to keep up with this growing demand for increased bandwidth data. The first lies in the use of optical fiber cable and the second is in the use of Visible Light Communication VLC. In this work, data transmission was studied using both methods. To achieve the first objective, two types of optical cable were used: one is the single mode and the other type multi mode. They were used in an indoor wireless communication system. Different frequencies were sent by these optical fibers and received from the other part recording values (signal voltage) for each frequency in the recipient circuit where the frequencies were between (10KHz-100KHz) as well as recording the values of optical power for each frequency received and study the impact of changing the values of these frequencies on these parameters. On the other hand, Visible Light Communication system has designed a light communication system Light Fidelity or so-called (Li-Fi) using a Light Emitting Diode (LED) source in the transmitter circuit and put a solar cell in the receiving circuit. Both circuits contained a built-in circuit (Transistor Transistor Logic) or TTL for embedding and decoding of the transmitted and received data. Through this system, text data (numbers and letters) as well as images and videos were sent. The effect of changing the receiving angle and temperature and studying some parameters such as values Single to Noise Ratio (SNR), Video Quality Measurement (VQM), Structure Similarity Index (SSIM) and some other effects to compare the quality of pictures and videos before sending.
... VLC features a high bandwidth that could reach up to Terahertz (THz), in addition to low power, license-free deployment, and interference immunity [98], [99]. TABLE 3 provides a comparison between VLC and RF technologies [100], [101]. Similar to D2D communications, VLC system has limited coverage distance. ...
... RF versus VLC technologies[100],[101]. ...
Article
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Device-to-device (D2D) communication is one of the most promising technologies in wireless cellular networks that can be employed to improve spectral and energy efficiency, increase data rates, and reduce links latency. This paper investigates fifth generation and beyond (5GB) networks, the basics of D2D communication, applications, and classification. Herein, D2D in in-band (IBD) and out-band (OBD) modes are discussed. This paper also presents the integration of D2D communication with other prominent technologies and demonstrates the importance of integration with possible solutions in improving network performance. We further investigate the challenges of D2D communication, opportunities, and future research directions of D2D in 5GB networks. In addition, D2D communication in 6G network challenges and open research areas are introduced.
... For indoor communication using wireless technology, visible light communication (VLC) offers some advantages, such as green technologies and cost-effective [8]. VLC technology works by using the light spectrum, which has wavelengths from 375 to 780 nm. ...
Article
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Visible Light Communication (VLC) has been attracting many researchers in the last decade to develop a lighting system as well as a communication system simultaneously. Light Emitting Diode (LED) for lighting systems are becoming more popular and widespread. It offers low consumption energy due to its energy transfer efficiency from electric to light. LED also offers a high response for modulation that makes it is also possible for communication purposes. Therefore, an improved configuration can provide a green communication system by reducing power consumption through combining lighting and communication system. Detection responsivity is a challenging issue to realize a VLC system. It will affect covered areas and obtained signal quality. This paper discusses the use of PIN photodiode and Avalanche Photo Diode (APD) for a detection device in a digital transmission data. This detector is generally used for fiber optic systems and offers an avalanche effect that can increase the obtained photocurrent. The obtained proper configuration and multiplication effect characteristics will be useful for designing a VLC system for green communication.
... One way to achieve this is to enforce a constraint of Hermitian symmetry on orthogonal sub-carriers in the frequency-domain. In [17], Tsonev et al. used the property that N-DFT taken of real values gives a conjugate symmetric coefficient which are around point N/2. This means that at the output of Inverse Fast Fourier Transform (IFFT) block, we can directly get real-value timedomain signal by enforcing conjugate symmetry also called Hermitian symmetry. ...
Article
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Free Space Optics (FSO) is an optical communication technique which disseminates light in free space such as air, vacuum or celestial space, to wirelessly transfer data. FSO communication offers high data rates up to 2.5 Gbps over a range of 100 m to a few kilometers and has the potential to replace the traditional means of communications in a wide variety of applications. Despite advantages such as high bandwidth and unlicensed spectrum, its widespread use has been inhibited by factors including interference and atmospheric turbulences. Many of these challenges have been addressed by researchers who have proposed modulation techniques, channel coding, diversity, hybrid systems and physical implementation of hardware. There is a need for a comprehensive review of contemporary research in FSO in order to examine the significant contributions and to identify open challenges and potential directions for future research endeavors. This paper presents a state-of-the-art review of the use of FSO in important indoor and outdoor applications and identifies some of the open research problems. We indicate the following open research problems: (a) the future FSO systems would offer both illumination and communication which necessitates modulation and coding techniques for a better dimming control along with efficient data communication, (b) security threats at the physical layer are a major concern to be addressed, (c) FSO transceiver design for future 5G systems faces a challenge of optimizing bit-error-rate and signal-to-noise ratio at the receiver, and (d) cost-effective hybrid RF/FSO solutions are needed to combine the benefits of RF and FSO.
... Visible light communication (VLC), which is a technology of using the same light emitting diodes (LEDs) both for illumination and data communication, is foreseen to be the integral component of the future heterogeneous mobile network [1][2][3][4]. The dominating LED-based light source on the market is a GaN blue chip covered with a phosphorous layer that converts the blue light to yellow, which combined together form light perceived by humans as white [5,6]. ...
Article
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In this study, the authors demonstrate that transmission rate in white phosphorescent light emitting diode (LED) transmitter communication‐illumination system can be increased significantly by simultaneous transmission of an additional infrared (IR) channel. Unlike in typical colour multiplexing, the IR channel does not require a dedicated receiver filter as the channel crosstalk can be removed using digital signal processing. Both channels can operate in synchronous or asynchronous mode. The experimental results in this study demonstrate a significant increase in the data rate.
... Another supporting condition is already widely deployment of lighting based on LED. Some potential applications of VLC for future communications are light-fidelity (Li-Fi) [4], vehicle to vehicle communications [5], and underwater communication [6]. The upcoming 5G has also been considering this technology to become part of its system [7]. ...
Conference Paper
In the last decades, research on visible light communication (VLC) has been attracting researchers to develop a wireless communication system based on visible light transmission. The advancement of LEDs for the lighting system is a factor in considering it for wireless communication purposes. Even though this technique can perform lighting and communication simultaneously for green communications, it suffers attenuation on the emitted power as distance increases and divergent beam from the LED source. This paper discusses light-waves power transmission of a light-emitting diode in a short-range distance. The transmitter consists of a microcontroller-based Arduino and LED. On the other part, the receiver uses the microcontroller and photodiode. The considered modulation is on-off keying (OOK) intended for the application of the IEEE 802.15.7 standard of specification PHY I for indoor communication. This experiment aims to measure the current and voltage received at photodiode from LED. In general, the result shows that the white LED can provide the highest received power than red, green, and blue. The received power decrease as the distance increase. The power degradation insight is useful for further a VLC system implementation.
... In this paper we study about the issue in security that possible occur in the LiFi. This study according to the VLC technology that still relate to the LiFi technology [2]. Our research is a review of the existing threat and vulnerabilities. ...
Article
Visible Light Communication (VLC) is an extension of Light Fidelity (LiFi) that uses full duplex communication or fully networked wireless communication. LiFi is one of the top technologies for solving wireless fidelity (WiFi) issues. Communication over LiFi is one of its major advantages. However, no security system is infallible. The purpose of this paper is to conduct a mini review of LIFI technology in terms of security issues. As a new technology, Lifi is still not widely known for its security issues. Literature reviews are a necessary step to determining the issues related to Lifi technology. A descriptive qualitative approach is used in this paper to describe the data. As a result, several studies have documented security issues related to LiFi technology, including data modification, spoofing, and jamming.
... After this achievement, numerous studies have been published on how to make use of white-LEDs in communication systems. Based on visible light communication (VLC) technology, light fidelity (Li-Fi) was then proposed in [10], [11] to form a small-cell wireless access network where multiple light sources in an indoor environment are used as access points (APs). Furthermore, in 2011, the first IEEE standard related to VLC (802. ...
Article
Full-text available
Wireless communications refer to data transmissions in unguided propagation media through the use of wireless carriers such as radio frequency (RF) and visible light (VL) waves. The rising demand for high data rates, especially, in indoor scenarios, overloads conventional RF technologies. Therefore, technologies such as millimeter waves (mmWave) and cognitive radios have been adopted as possible solutions to overcome the spectrum scarcity and capacity limitations of the conventional RF systems. In parallel, visible light communication (VLC) has been proposed as an alternative solution, where a light source is used for both illumination and data transmission. In comparison to RF links, VLC links present a very high bandwidth that allows much higher data rates. VLC exhibits also immunity to interference from electromagnetic sources, has unlicensed channels, is a very low power consumption system, and has no health hazard. VLC is appealing for a wide range of applications including reliable communications with low latency such as vehicle safety communication. Despite the major advantages of VLC technology and a variety of its applications, its use has been hampered by its cons such as its dependence on a line of sight connectivity. Recently, hybrid RF/VLC systems were proposed to take advantage of the high capacity of VLC links and better connectivity of RF links. Thus, hybrid RF/VLC systems are envisioned as a key enabler to improve the user rates and mobility on the one hand and to optimize the capacity, interference and power consumption of the overall network on the other hand. This paper seeks to provide a detailed survey of hybrid RF/VLC systems. This paper represents an overview of the current developments in the hybrid RF/VLC systems, their benefits and limitations for both newcomers and expert researchers.
... In [7] the idea of using light to transmit signal from the source to destination is discussed. In [8], the light fidelity (Li-Fi) technology which is based on VLC technology is proposed by the authors. The advantages and limitation of using the VLC in 5G systems is also discussed in [9]. ...
Article
In this research paper, we propose a two-hop integrated radio frequency-visible light communication (RF-VLC) system which may provide a better option to transceive between the hospitals and some laboratory to transfer patient’s information. In the proposed system model, the data (such as patient’s lab test reports) is transmitted towards the amplify and forward (AF) relay mounted on the top of the hospital building via the RF channel. Further, the AF relay amplifies and converts the received information into corresponding optical signal using light emitting diodes (LED) and supporting circuitry. This optical signal is then forwarded towards the destination device (equipped with VLC transceiver), via the VLC channel. To analyse the performance of the system, we first derive the closed form analytical expressions for the cumulative distribution function (CDF) of the end-to-end (e2e) signal to noise ratio (SNR) of the system by using the moment generating function (MGF) of the SNR of the individual RF and VLC channels. Further, we use these statistical expressions to obtain the outage probability, average bit error rate (BER) and the average capacity of the system. Moreover, the asymptotic performance of the proposed system is also analysed to study the system’s behaviour at high SNR regimes. Finally, we studied the impact of the variations in channel parameters on the proposed system model performance through numerically simulated plots.
... [79] In addition, OWC with dual functionality, like Light Fidelity (Li-Fi), was suggested for simultaneous lighting and communication purposes due to the high energy efficiency of these high-speed optical emitters. [80] However, OWC has evolved rapidly compared to UOWC and the main reason behind this delay is the complexity of the aquatic environments. Various monitor the behaviour of underwater light, researchers conducted several theoretical and experimental studies. ...
Article
Full-text available
Even though most of the Earth's area is sheltered by the hydrosphere, the underwater world is nonetheless a challenging puzzle that has drawn the attention of scientists and researchers around the globe. Numerous theoretical and experimental research has been conducted to attain a safe and effective means of communication. This is crucial to facilitate the implementation of critical industrial, military and security applications and to guarantee the management of marine resources sustainably. Underwater communication technologies have come a long way as they have been implemented either utilizing wired and wireless techniques, through employing acoustic waves or electromagnetic waves (in the radio-frequency spectrum or the optical spectrum). Even though acoustic communication realizes long communication ranges in Km, its limited data rate, its low speed, and its undesirable impact on the aquatic environment have all led to the realization of electromagnetic waves-based communication. Electromagnetic waves offer a high data rate and high-speed communication. Moreover, underwater radio frequency communications maintain a smooth transition between water and air, and they are unaffected by the turbidity properties of water. However, they come at a huge cost. Intriguingly, wireless communications in the optical spectrum have outperformed all the above techniques. This is owing to its high bandwidth and low cost. For that reason, we focus this review on the different facets of the underwater optical wireless communications (UOWC) field, where we present an overview of the most important communication techniques and highlight their drawbacks and advantages. We also review the most basic physical processes that influence the light propagation and modulation underwater along with the coding techniques. We then discuss the link configurations and the system design, and we provide a summary of the most prominent studies from 1992 to the present.
... Light bulbs will play the role of "air traffic control towers", modulating their intensities to provide navigation services to drones. To achieve this goal, Firefly exploits recent advances in visible light communication (VLC) [12], an emerging technology that transmits information using any type of LED. The core idea behind VLC is similar to communicating with somebody by turning a flashlight on and off. ...
Preprint
Drones are not fully trusted yet. Their reliance on radios and cameras for navigation raises safety and privacy concerns. These systems can fail, causing accidents, or be misused for unauthorized recordings. Considering recent regulations allowing commercial drones to operate only at night, we propose a radically new approach where drones obtain navigation information from artificial lighting. In our system, standard light bulbs modulate their intensity to send beacons and drones decode this information with a simple photodiode. This optical information is combined with the inertial and altitude sensors in the drones to provide localization without the need for radios, GPS or cameras. Our framework is the first to provide 3D drone localization with light and we evaluate it with a testbed consisting of four light beacons and a mini-drone. We show that, our approach allows to locate the drone within a few decimeters of the actual position and compared to state-of-the-art positioning methods, reduces the localization error by 42%.
... In the following, the requirements for deploying VLC precoding schemes are presented: Uplink and CSI: VLC systems naturally consider a frequency division duplex (FDD) operation mode. Although downlink typically occurs in the visible optical domain, infrared (IR) communications [142,143] or umbrella RF networks such as WiFi or femtocells [144,145] are considered for implementing the uplink transmission. Notice that time division duplex (TDD) requires one to transmit both downlink and uplink through the visible optical domain, which may be annoying for practical implementations. ...
Article
Full-text available
Visible light communications (VLC) have received significant attention as a way of moving part of the saturated indoor wireless traffic to the wide and unregulated visible optical spectrum. Nowadays, VLC are considered as a suitable technology, for several applications such as high-rate data transmission, supporting internet of things communications or positioning. The signal processing originally derived from radio-frequency (RF) systems such as cooperative or precoding schemes can be applied to VLC. However, its implementation is not straightforward. Furthermore, unlike RF transmission, VLC present a predominant line-of-sight link, although a weak non-LoS component may appear due to the reflection of the light on walls, floor, ceiling and nearby objects. Blocking effects may compromise the performance of the aforementioned transmission schemes. There exist several surveys in the literature focused on VLC and its applications, but the management of the shadowing and interference in VLC requires a comprehensive study. To fill this gap, this work introduces the implementation of cooperative and precoding schemes to VLC, while remarking their benefits and drawbacks for overcoming the shadowing effects. After that, the combination of both cooperative and precoding schemes is analyzed as a way of providing resilient VLC networks. Finally, we propose several open issues that the cooperative and precoding schemes must face in order to provide satisfactory VLC performance in indoor scenarios.
... But also contains some drawbacks like interchannel interference, high computational complex algorithms, inter-antenna synchronisation, multiple radio frequency(RF) chains and error propagation. On the other hand, spatial multi-plexing which is used in LiFi systems are capable of avoiding inter-channel interference, no need for synchronisation, no constraints for number of devices and only single RF chain is required at the transmitter [6]. VLC technology is definitely indicating important cornerstones. ...
Conference Paper
Full-text available
Researches have been conducted on Optical Wireless Communication (OWC) technology for a decade now, and because of the complexity, it naturally took a long way to become applicable for practical use cases. Current access systems are not sufficient to meet the continuously increasing demand on network performance of various applications. Visible Light Communication (VLC) is a form of OWC which specialized to use visible light. It is a promising innovation as it exploits new spectrum having favorable propagation and interference characteristics for various use cases. This paper aims at introducing a solution for integration of VLC with 5th Generation (5G) network systems. The offered solution also contains details of handover mechanism between licensed and unlicensed access types. The proposed work demonstrates the optical communication with 5G-based network systems in a common infrastructure in order to supply enhanced connectivity for industrial and private applications that require robust data links, less data loss, less downtime and higher uplink and downlink rates. Thus, improving connectivity at where Radio Frequency (RF) is not able to bring adequate performance like indoors. Our setup comprises two different data paths: one via a 5G system over standardized 3rd Generation Partnership Project (3GPP) components and the other via non-3GPP unlicensed access with the Light Fidelity(LiFi) devices over non-3GPP Interworking Function (N3IWF).
... The usage of the optical spectrum for indoor data transmission can be easily enabled through off-the-shelf optical components such as light-emitting diodes (LEDs) and simple baseband processing. The VLC system appeared to overwhelmed the restrictions levied by the nature of radio-frequency based wireless communication systems and in comparison, VLC brings many enticing features which are itemized as [5][6][7][8][9]: ...
Article
Optical orthogonal frequency-division multiplexing (OFDM) has proven to be an effective technique for the visible light communication (VLC) system in which data is sent and received through the intensity-modulated/direct-detected optical channel. However, OFDM exhibits high peak-to-average power ratio (PAPR) and for the generation of real-valued signal employs Hermitian symmetry (HS) of the frequency symbols which in turn boost the computational complexity (CC) and deteriorates the performance of the system. Besides, OFDM also included cyclic prefix (CP) as redundancy that reduces the spectral efficiency. This paper aims to target the aforesaid OFDM issues and introduce a novel technique in the form of wavelet transform (WT) based on non-HS OFDM (NHS-OFDM). In the proposed technique, an N -point complex OFDM signal is generated by utilizing wavelets as basis function, from which real and imaginary components are extracted and then concatenated to form a 2 N -point real signal. The work also confirmed that the CC of the proposed technique is about 83% less than the conventional Fourier transform (FT) based NHS-OFDM technique due to which reduction in PAPR and bit error rate (BER) improvement is also noticed from the simulated results. The superior performance of WT based NHS-OFDM technique is further verified via experiments conducted by interfacing the computer terminal with Raspberry Pi (RPi) 3b+ modules. In the designed VLC prototype, the NHS-OFDM modem work as the software-defined radio (SDR) on a stand-alone computer. The experiment results reveal that real-time text message is transmitted and received without error at the communication range of 1.75 m while the data rate attains from the prototype is 3.921 Mbps.
... VLC signal modulation is totally different from terrestrialbased communication cause of non-encoding features in phase, and amplitude [198]. In general, the accomplishment of LEDs in the VLC system has triple features as illumination, high-speed data communication, and energy harvesting simultaneously [27]. ...
Article
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In recent years, underwater visible light communication (UVLC) has become a potential wireless carrier candidate for signal transmission in highly critical, unknown, and acrimonious water mediums such as oceans. Unfortunately, the oceans are the least explored reservoirs in oceanogeographical history. However, natural disasters have aroused significant interest in observing and monitoring oceanic environments for the last couple of decades. Therefore, UVLC has drawn attention as a reliable digital carrier and claims a futuristic optical media in the wireless communication domain. Counterparts of traditional communications, the green, clean, and safe UVLC support high capacity data-rate and bandwidth with minimal delay. Nevertheless, the deployment of UVLC is challenging rather than terrestrial basis communication over long ranges. In addition, UVLC systems have severe signal attenuation and strong turbulence channel conditions. Due to the fact that, this study provides an exhaustive and comprehensive survey of recent advancements in UVLC implementations to cope with the optical signal propagation issues. In this regard, a wide detailed summary and future perspectives of underwater optical signaling towards 5G and beyond (5GB) networks along with the current project schemes, channel impairments, various optical signal modulation techniques, underwater sensor network (UWSN) architectures with energy harvesting approaches, hybrid communication possibilities, and advancements of Internet of underwater things (IoUTs) are concluded in this research.
... Visible light communication arises as to the latest research trend in indoor optical wireless communication (OWC), which contributes the most matured and robust solutions to many issues. Nowadays, VLC is not only limited to being a source of light in home networking but also provides highspeed communication networks via light links in offices, airplanes, traffic light signals, etc. [3,4]. In the last few years, growing research in VLC shows the reliability and power efficiency offered by LED, which is to date much more remarkable than any conventional incandescent source of light used for lighting. ...
Article
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This paper illustrates the impact of wavelength on the Optical Line of sight (OLOS) link working in the Visible Light Communication (VLC) spectrum. The extension of work is based on previous outcomes given by researchers. It has been elaborated with different determinants based on the color factor of LED available in the Visible Light (VL) spectrum. In the modern world, Light Emitting Diodes (LEDs) are prevailing the market as a light source, which is dominantly used at homes and workplaces. The designed VLC system includes LED as a transmitter, which is used as a higher source of brightness and provides both illuminations and data communication. Solid-state lighting characteristic shows the electroluminance capability of high brightness LEDs. Within few years, the luminous efficacy of LED is exponentially increasing from the range of less than 0.1 lm/W to over 230 lm/W with a huge lifetime of around 100,000 h. MATLAB is used to simulate a VLC link between LEDs (operated at different wavelengths) and photodetector. We present here the performance analysis of Lambertian Luminous Intensity radiation pattern (LLIRP) generated by different colors of LED for a clear OLOS model with different Spectral Luminous Efficiency at photonic vision. A designed system model of VLC supports short links present in indoor room conditions with better connectivity.
... Light with wavelength ranging from 380nm to 780nm is used for data communication between LEDs and photo detectors www.ijsart.com [10][11][12]. Li-Fi can support three different modes, namely peer to peer, broadcast, and star. It can be used for different applications like street lights and signboards. ...
Article
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Every social being need communication for a better life. Exponential growth is taking place in Wi-Fi connections and data transfer now a days. The 5G technology for data transfer, Li-Fi(Light Fidelity) invented by Prof. Harald Haas in 2011 is a wireless networking technology by means of LED light using the principle of Visible Light Communication. Recent research shows that by 2022, 74zetta bytes of data will be generated. As data volume goes up exponentially and generating demand for electromagnetic spectrum, which will cause damage to human as well as animal health. In such situations, Li-Fi performs well to get data quickly and the applications of Li-Fi include hospitals, under water communication, Schools, Military operations, Business and many more. Also the situations where transmission of radio frequencies is hazardous such as chemical plants or petroleum plants, data transmission can be replaced by Li-Fi technology instead of using Wi-Fi. This paper reviews the Li-Fi technology and lists out the advantages and limitations which will help for further research.
... Li-Fi can be used in numerous applications like in emergency clinic [1][2][3]. It will be helpful in schools allowing learning apps in mobile devices used in aircrafts without causing electromagnetic interference and also for underwater communication [4][5]. ...
... Since the light is faster than RF waves, it provides a massive data rate, enhancement for channel capacity, high spectral efficiency and more security. OWC utilized Infra-Red (IR), visible light communication (VLC), and ultraviolet (UV) frequencies of the electromagnetic spectrum [1,2]. ...
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... The MQ-8 gas module is fixed on a PCB board which operates on a voltage of 5V DC. The sensor output values can be received by means of both analog and digital [10]. For detecting the LPG gas this sensor is most preferred. ...
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... Additionally, other wireless protocols, including light-based ones, have been proposed as a way of mitigating some of the issues (e.g., electromagnetic interference) that affect most of the protocols above to some degree. Among such initiatives, one can identify Li-Fi (Light-Fidelity), a derivative of optical wireless communications (OWC) technology, that uses light-emitting diodes (LED) for transmitting data [72]. Another widely-used light-based communication technology is infrared (IR), which has been historically used (standardized by IrDA and IEEE in the early 90s) as a low-range communication protocol solution and still plays a role in IoT due to its low power consumption [73,74]. ...
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Optical wireless communication (OWC) refers to any kind of communication based on light as a wireless transmission medium.
Thesis
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Wireless communication refers to data transfer in an unguided propagation medium through wireless carriers such as visible light (VL) and radio frequency (RF). The rapidly growing demand for high data rates overloads conventional RF wireless communication. Therefore, technologies such as cognitive radios and millimeter waves (mmWaves) have been utilized to overcome capacity limitation and spectrum scarcity of RF systems. In parallel, optical wireless communication (OWC) is a promising alternative solution to its radio frequency (RF) compeer. OWC has been revolutionized to support fifth generation (5G) wireless communication and Internet-of-Things (IoT) terminals. In addition, OWC has no health hazard, low power consumption, unlicensed spectrum and shows immunity to interferences from electromagnetic sources. As RF and OWC are compatible, so a joint application scenario is referred as an excellent solution to support 5G and beyond systems. Hybrid optical/optical and RF/optical system is a promising approach to remove the limitations of each system as well as to enable supporting features of each technology. An optical/optical hybrid system is based on two or more OWC technologies while RF/optical hybrid system contains both RF and OWC technologies. The hybrid systems can enhance system performance in terms of energy efficiency, reliability and throughput of each system. Thus, hybrid RF/optical systems are envisioned as a key enabler to enhance user mobility and data rate on the one hand and to optimize power consumption, network load, interference and network capacity on the other hand. This survey seeks to provide the state-of-the-art and future research directions regarding optical wireless hybrid networks. This paper represents a technological overview of existing optical wireless hybrid networks. We have discussed optical-based free-space optics (FSO), optical camera communication (OCC), light fidelity (LiFi) which extends the concept of visible light communication (VLC) to attain bi-directional and fully networked wireless communication, as well as RF-based Bluetooth, wireless fidelity (WiFi), small cell, macrocell, mmWave and microwave. In addition, we have also considered underwater acoustic communication for acoustic/optical and acoustic/RF hybrid networks. An extensive range of applications such as indoor, vehicular communication, eHealth, backhaul connectivity solution and underwater communication is considered. We have addressed potential challenges and open research issues for design and successful deployment of hybrid wireless networks.
Chapter
Silicon photomultiplier (SiPM) has several attracting features, which can be helpful in the communication field, such as high photon detection efficiency, fast transient response, excellent timing resolution, and wide spectral range. In this paper, we compare SiPM with photodiode (PD), avalanche photodiodes (APD), and photomultiplier tube (PMT) in terms of the transformation related performance. Based on SiPM and visible light light-emitting diode (LED), we implement visible light communication (VLC) system, and conduct numerical simulation experiment research to convert data transmission problems into signal processing problems. In addition, we also propose the SR algorithm, which compares and analyzes with the PMID and FD algorithms used before. The system throughout ability, transmission rate, and data reconstruction are evaluated. The encouraging results suggest that the SiPM receiver has great application potentials, such as optical wireless communication systems and light fidelity, in which a wide bandwidth of the sensor response is important to enhance the transfer rate.
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This paper introduces a novel and promising design of a freeform diversity receiver (FDR) to reduce the inter-channel interference (ICI) of multi-cell visible light communication (VLC) system. Based on the potential of rotationally non-symmetric freeform optics, we have established the design of an off-axis VLC receiver front-end. In this study, we have performed the detailed design of the freeform surface profiles and have analysed the corresponding fabrication tolerances. Nonetheless, the communication performance of the VLC system using the proposed design has been evaluated with the help of Monte-Carlo based ray-tracing technique. Results show that the system with the proposed FDR significantly outperforms the existing state-of-the-art multi-cell VLC receivers in terms of signal-to-interference-plus-noise ratio (SINR). The spatial SINR ranges from 98 dB to 137 dB while 120.5 dB average SINR is attained over the communication floor. This compact size receiver (15.12 mm × 15.12 mm × 6.76 mm) with substantial wireless reception reliability has prospective future applications in the emerging field of visible light communication and its counterpart Li-Fi.
Chapter
Recent results have made a promising case for offering oversubscribed wired data center networks (DCN) with extreme costs. Inter-rack wireless networks are drawing intensive attention to augment such wired DCNs with a few wireless links. For this reason, we propose a hybrid network topology, VLCcube, which consists of wireless links and wired links, by introducing extra visible light communication (VLC) links into data centers. Specifically, VLCcube augments Fat-Tree, a representative DCN in production data centers, by installing 4 VLC transceivers on top of each rack for constructing four wireless links of 10 Gbps. These wireless links improve the network capacity of wired links and organize all racks into a wireless Torus structure. This chapter focuses on the topology design, hybrid routing, and flow scheduling schemes for VLCcube, and carries out related experiments to show its performance. VLCcube has better network performance than Fat-Tree since many flows transmitting along 4-hop paths in Fat-Tree can achieve a shorter transmission range if they are transmitted in the wireless Torus. The congestion-aware flow scheduling algorithm can further improve the performance of VLCcube. Actually, VLCcube is just one alternative to the utilization of VLC links in data centers. The introduction of VLC links integrates seamlessly with the existing DCNs, and it improves the performance and design flexibility of DCNs effectively.
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Chapter
Smart city is a metropolitan improvement utilizing information and communications technology (ICT) and Internet of things (IoT) for providing valuable data to successfully manage the resources of the Internet. Data transfer within a smart city through wireless communication is very important aspects nowadays. There were certain limitations for conventional wireless communication using radio frequency (RF) like interference, spectrum crunch, restriction in IoT-enabled device, health hazards. A novel approach of data communication is proposed for secured data transmission using the visible light. Light fidelity (Li-Fi) is a wireless communication technology that uses light to interchange data among the devices. To implement smart home application, Li-Fi technology can be modeled and integrated with Arduino UNO for efficient data transmission. A machine intelligence algorithm is deployed to make the model intelligent.
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Light Fidelity (Li-Fi) is an advanced visible light communication (VLC) technic in which light emitting diodes (LEDs) are used for data transfer. In this article, a Li-Fi system using LED arrays is examined for indoor visible light communication. Lighting and data transmission simulations are made for return to zero on off keying (OOK-RZ) and 4-ary pulse position modulation (4-PPM) techniques with taking into account the optical path differences. Signal to noise ratios (SNRs) for both modulation techniques are calculated and used for comparison. Results of the simulations showed that data transmission rate up to 500 Mbps at FOV angle of 60° can be achieved for both modulation techniques.
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This paper studies the capacity of the two-user intensity-modulation/direct-detection (IM/DD) interference channel (IC), which is relevant in the context of multi-user optical wireless communications. Despite some known single-letter capacity characterizations for general discrete-memoryless ICs, a computable capacity expression for the IM/DD IC is missing. In this paper, we provide tight and easily computable inner and outer bounds for a general two-user IM/DD IC under peak and average optical intensity constraints. The bounds enable characterizing the asymptotic sum-rate capacity in the strong and weak interference regimes, as well as the generalized degrees of freedom (GDoF) in the symmetric case. Using the obtained bounds, the GDoF of the IM/DD IC is shown to have a `W' shape similar to the Gaussian IC with power constraints. The obtained bounds are also evaluated numerically in different interference regimes to show their tightness, and used to study the performance of on-chip and indoor OWC systems.
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Visible light communication (VLC) is a promising candidate that is expected to revolutionize indoor environment communications performance and fulfill fifth generation and beyond (5GB) technologies requirements. It offers high and free bandwidth, electromagnetic interference immunity, low-cost front end and low power consumption. Also, VLC has dual functions that could be utilized in both illumination and communication concurrently. The number of optical attocells (OAs) and their deployment in the room represent the main issue that should be taken into consideration in designing an optimal VLC system. In this paper, we have introduced a new model of five OAs in the typical room. In addition to an investigation of various optical attocells (OAs) deployment models, in which a multi-variable evaluation was performed in terms of received power, illumination, SNR and RMS delay spread in order to determine the optimal OAs model. Also, various modulation schemes performances were investigated which included NRZ-OOK, BPSK, and QPSK in order to improve the BER performance. Results indicated that BPSK modulation had superior BER performance when compared with all OAs models. Further, a comprehensive results analysis and comparison of all proposed models was conducted over various parameters, in which our new proposed OAs model achieved an optimal performance in comparison with the other models
Conference Paper
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Wireless network data consumption is experiencing drastic increases due to growing demands of mobile services and applications. Deployed networks using Radio Frequency (RF) communications are characterized by a shared medium, limited available spectrum and limited ability to scale with increasing demand. Directional communications, including Visible Light Communications (VLC), can limit contention in controlled environments and provide scalability through spatial reuse of the medium. This solution can provide massive aggregate data capacity in indoor scenarios if properly distributed. In this paper we propose an indoor hybrid system that integrates WiFi and VLC luminaries. Our system utilizes (i) broadcast VLC channels to supplement RF communications and (ii) a handover mechanism between WiFi and VLC to dynamically distribute resources and optimize system throughput. This approach offers the bandwidth density benefits of VLC, provides a non-intrusive RF back-channel, maintains compatibility with conventional RF devices, and demonstrates excellent scalability. Analytical and simulation results show improvements in aggregate performance (i.e., throughput and delay) of the hybrid, when compared to either system acting alone.
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In this paper, a piecewise polynomial function is proposed as a generalized model for the nonlinear transfer characteristic of the transmitter for optical wireless communications (OWC). The two general multicarrier modulation formats for OWC based on orthogonal frequency-division multiplexing (OFDM), direct-current-biased optical OFDM (DCO-OFDM) and asymmetrically clipped optical OFDM (ACO-OFDM), are studied. The nonlinear distortion of the electrical signal-to-noise ratio (SNR) at the receiver is derived in closed form, and it is verified by means of a Monte Carlo simulation. This flexible and accurate model allows for the application of pre-distortion and linearization of the dynamic range of the transmitter between points of minimum and maximum radiated optical power. Through scaling and DC-biasing the transmitted signal is optimally conditioned in accord with the optical power constraints of the transmitter front-end, i.e., minimum, average and maximum radiated optical power. The mutual information of the optimized optical OFDM (O-OFDM) schemes is presented as a measure of the capacity of these OWC systems under an average electrical power constraint. When the additional DC bias power is neglected, DCO-OFDM is shown to achieve the Shannon capacity when the optimization is employed, while ACO-OFDM exhibits a 3-dB gap which grows with higher information rate targets. When the DC bias power is counted towards the signal power, DCO-OFDM outperforms ACO-OFDM for the majority of average optical power levels with the increase of the information rate target or the dynamic range. The results can be considered as a lower bound on the O-OFDM system capacity.
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In this paper wireless communication using white, high brightness LEDs (light emitting diodes) is considered. In particular, the use of OFDM (orthogonal frequency division multiplexing) for intensity modulation is investigated. The high peak-to-average ratio (PAR) in OFDM is usually considered a disadvantage in radio frequency transmission systems due to non-linearities of the power amplifier. It is demonstrated theoretically and by means of an experimental system that the high PAR in OFDM can be exploited constructively in visible light communication to intensity modulate LEDs. It is shown that the theoretical and the experimental results match very closely, and that it is possible to cover a distance of up to one meter using a single LED
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We consider two uniploar OFDM techniques for optical wireless communications: asymmetric clipped optical OFDM (ACO-OFDM) and Flip-OFDM. Both techniques can be used to compensate multipath distortion effects in optical wireless channels. However, ACO-OFDM has been widely studied in the literature, while the performance of Flip-OFDM has never been investigated. In this paper, we conduct the performance analysis of Flip-OFDM and propose additional modification to the original scheme in order to compare the performance of both techniques. Finally, it is shown by simulation that both techniques have the same performance but different hardware complexities. In particular, for slow fading channels, Flip-OFDM offers 50% saving in hardware complexity over ACO-OFDM at the receiver.
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We examine systems of fixed-channel reuse for base stations in an indoor infrared wireless communication system. The following techniques are compared: time-division multiple access (TDMA) using on-off keying (OOK) or pulse-position modulation (PPM); frequency-division multiple access (FDMA) using binary phase-shift keying (BPSK) or quadrature phase-shift keying (QPSK); code-division multiple access (CDMA) using OOK with direct-sequence spreading by m-sequences or optical orthogonal codes (OOCs). We define a parameter γ, which equals the signal-to-noise ratio (SNR) for unit optical path gain and is proportional to the square of the transmitted average optical power. Using measured pathloss data, it is found that in a system using hexagonal cells and a reuse factor of three, for cell radii above 3 m, TDMA with OOK or 2-PPM, and CDMA using OOCs all require approximately the same γ to achieve a worst-case bit-error rate (BER) of 10<sup>-9</sup> within a cell. Using TDMA with 4-PPM results in a 6-dB decrease in the required value of γ. CDMA using m-sequences requires an increase in γ of 5 dB over TDMA using OOK, and FDMA with BPSK requires an increase of 12 dB. For a given reuse factor N in the noise-limited regime, the required value of γ decreases in inverse proportion to N<sup>2</sup> for TDMA schemes and inversely with N for FDMA and CDMA schemes. For cell radii below 3 m, cochannel interference dominates the systems using TDMA, FDMA, and CDMA with an OOC, resulting in an irreducible BER above 10<sup>-9</sup> at cell radii below 1.5 m. Only CDMA with m-sequences does not develop an irreducible BER, making it the only choice for cell radii below 1.5 m
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A novel concept of pulse-amplitude-modulated discrete multitone modulation (PAM-DMT) is presented. It is shown that by pulse amplitude modulation of the subcarriers used, the resulting PAM-DMT time signal can be clipped asymmetrically to achieve a unipolar signal for transmission. The distortion resulting from this asymmetric clipping is orthogonal to the information signal itself, causing no additional penalty. Especially in intensity-modulated direct-detection optical channels, where a unipolar signal is to be transmitted, it is shown that this idea can improve system performance.
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Femtocells help eliminate spotty mobile phone reception indoors by connecting users to the wireless network via broadband Internet links, not the telephony infrastructure.