Engineering › Electrical and Electronic Engineering

Optical Wireless Communication Technologies

Works Count: 36095

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Description

This cluster of papers focuses on the advancements, challenges, and applications of optical wireless communication systems and technologies, including visible light communication, free-space optical communication, underwater optical communication, MIMO techniques, and channel modeling. It covers topics such as indoor positioning systems, high data rate transmission, LED-based communication, and the effects of atmospheric turbulence.

Keywords

Visible Light Communication; Free-Space Optical Communication; Underwater Optical Communication; Optical Wireless Networks; LED-Based Communication; Atmospheric Turbulence Effects; MIMO Techniques; Indoor Positioning Systems; High Data Rate Transmission; Channel Modeling

Free Space Optics: Enabling Optical Connectivity in Today's Networks

2001-11-01

H. Willebrand , Baksheesh S. Ghuman

From the Publisher: Free Space Optics will begin with the fundamentals of the technology before launching into FSO topologies, deployment issues, applications, and case studies. From the Publisher: Free Space Optics will begin with the fundamentals of the technology before launching into FSO topologies, deployment issues, applications, and case studies.

Mathematical model for the irradiance probability density function of a laser beam propagating through turbulent media

2001-08-01

M. A. Al-Habash , Larry C. Andrews , Ronald L. Phillips

We develop a model for the probability density function (pdf) of the irradiance fluctuations of an optical wave propagating through a turbulent medium. The model is a two-parameter distribution that … We develop a model for the probability density function (pdf) of the irradiance fluctuations of an optical wave propagating through a turbulent medium. The model is a two-parameter distribution that is based on a doubly stochastic theory of scintillation that assumes that small-scale irradiance fluctuations are modulated by large-scale irradi- ance fluctuations of the propagating wave, both governed by indepen- dent gamma distributions. The resulting irradiance pdf takes the form of a generalized K distribution that we term the gamma-gamma distribution. The two parameters of the gamma-gamma pdf are determined using a recently published theory of scintillation, using only values of the refractive-index structure parameter C n (or Rytov variance) and inner scale l 0 provided with the simulation data. This enables us to directly calculate various log-irradiance moments that are necessary in the scaled plots. We make a number of comparisons with published plane wave and spherical wave simulation data over a wide range of turbu- lence conditions (weak to strong) that includes inner scale effects. The gamma-gamma pdf is found to generally provide a good fit to the simu- lation data in nearly all cases tested. © 2001 Society of Photo-Optical Instrumen-

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Performance Comparison of MIMO Techniques for Optical Wireless Communications in Indoor Environments

2013-02-01

Thilo Fath , Harald Haas

In this paper, we compare the performance of multiple-input-multiple-output (MIMO) techniques applied to indoor optical wireless communications (OWC) assuming line-ofsight (LOS) channel conditions. Specifically, several 4 × 4 setups with … In this paper, we compare the performance of multiple-input-multiple-output (MIMO) techniques applied to indoor optical wireless communications (OWC) assuming line-ofsight (LOS) channel conditions. Specifically, several 4 × 4 setups with different transmitter spacings and different positions of the receiver array are considered. The following MIMO algorithms are considered: Repetition Coding (RC), Spatial Multiplexing (SMP) and Spatial Modulation (SM). Particularly, we develop a framework to analytically approximate the bit error ratios (BERs) of these schemes and verify the theoretical bounds by simulations. The results show that due to diversity gains, RC is robust to various transmitter-receiver alignments. However, as RC does not provide spatial multiplexing gains, it requires large signal constellation sizes to enable high spectral efficiencies. In contrast, SMP enables high data rates by exploiting multiplexing gains. In order to provide these gains, SMP needs sufficiently low channel correlation. SM is a combined MIMO and digital modulation technique. We show that SM is more robust to high channel correlation compared to SMP, while enabling larger spectral efficiency compared to RC. Moreover, we investigate the effect of induced power imbalance between the multiple transmitters. It is found that power imbalance can substantially improve the performance of both SMP and SM as it reduces channel correlation. In this context, we also show that blocking some of the links is an acceptable method to reduce channel correlation. Even though the blocking diminishes the received energy, it outweighs this degradation by providing improved channel conditions for SMP and SM. For example, blocking 4 of the 16 links of the 4 × 4 setup improves the BER performance of SMP by more than 20 dB, while the effective signal to noise ratio (SNR) is reduced by about 2 dB due to the blocking. Therefore, MIMO techniques can provide gains even under LOS conditions which provide only little channel differences.

34 Gbit/s visible optical wireless transmission based on RGB LED

2012-12-04

G. Cossu , Arslan Khalid , Pallab K. Choudhury +2 more

In this paper, we experimentally realized a gigabit-class indoor visible light communication system using commercially available RGB White LED and exploiting an optimized DMT modulation. We achieved data rate of … In this paper, we experimentally realized a gigabit-class indoor visible light communication system using commercially available RGB White LED and exploiting an optimized DMT modulation. We achieved data rate of 1.5 Gbit/s with single channel and 3.4 Gbit/s by implementing WDM transmission at standard illumination levels. In both experiments, the resulting bit error ratios were below the FEC limit. To the best of our knowledge, these values are the highest ever achieved in VLC systems.

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Electromagnetic beam propagation in turbulent media

1975-01-01

Ronald L. Fante

The most recent developments on the propagation of optical beams in a turbulent medium, such as the clear atmosphere, are reviewed. Among the phenomena considered are beam spreading, beam wander, … The most recent developments on the propagation of optical beams in a turbulent medium, such as the clear atmosphere, are reviewed. Among the phenomena considered are beam spreading, beam wander, loss of coherence, scintillations, angle-of-arrival variations, and short-pulse effects.

A Gigabit/s Indoor Wireless Transmission Using MIMO-OFDM Visible-Light Communications

2012-12-08

Ahmad Helmi Azhar , Tuan‐Anh Tran , Dominic O’Brien

This letter reports an experimental demonstration of indoor wireless visible-light communication transmission at 1 Gb/s. The system consists of a four-channel multiple-input multiple-output link that uses white LED sources, each … This letter reports an experimental demonstration of indoor wireless visible-light communication transmission at 1 Gb/s. The system consists of a four-channel multiple-input multiple-output link that uses white LED sources, each transmitting signals at 250 Mb/s using orthogonal frequency division multiplexing modulation. A nine-channel imaging diversity receiver is used to detect the signals, and an average bit error rate of 10 -3 is achieved at the room illumination level of ~1000 lux at 1-m range.

Survey on Free Space Optical Communication: A Communication Theory Perspective

2014-01-01

Mohammad‐Ali Khalighi , Murat Uysal

Optical wireless communication (OWC) refers to transmission in unguided propagation media through the use of optical carriers, i.e., visible, infrared (IR), and ultraviolet (UV) bands. In this survey, we focus … Optical wireless communication (OWC) refers to transmission in unguided propagation media through the use of optical carriers, i.e., visible, infrared (IR), and ultraviolet (UV) bands. In this survey, we focus on outdoor terrestrial OWC links which operate in near IR band. These are widely referred to as free space optical (FSO) communication in the literature. FSO systems are used for high rate communication between two fixed points over distances up to several kilometers. In comparison to radio-frequency (RF) counterparts, FSO links have a very high optical bandwidth available, allowing much higher data rates. They are appealing for a wide range of applications such as metropolitan area network (MAN) extension, local area network (LAN)-to-LAN connectivity, fiber back-up, backhaul for wireless cellular networks, disaster recovery, high definition TV and medical image/video transmission, wireless video surveillance/monitoring, and quantum key distribution among others. Despite the major advantages of FSO technology and variety of its application areas, its widespread use has been hampered by its rather disappointing link reliability particularly in long ranges due to atmospheric turbulence-induced fading and sensitivity to weather conditions. In the last five years or so, there has been a surge of interest in FSO research to address these major technical challenges. Several innovative physical layer concepts, originally introduced in the context of RF systems, such as multiple-input multiple-output communication, cooperative diversity, and adaptive transmission have been recently explored for the design of next generation FSO systems. In this paper, we present an up-to-date survey on FSO communication systems. The first part describes FSO channel models and transmitter/receiver structures. In the second part, we provide details on information theoretical limits of FSO channels and algorithmic-level system design research activities to approach these limits. Specific topics include advances in modulation, channel coding, spatial/cooperative diversity techniques, adaptive transmission, and hybrid RF/FSO systems.

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<title>Comparison of laser beam propagation at 785 nm and 1550 nm in fog and haze for optical wireless communications</title>

2001-02-06

Isaac I. Kim , Bruce A. McArthur , Eric J. Korevaar

12 There is currently a misconception among designers and users of free space laser communication (lasercom) equipment that 1550 nm light suffers from less atmospheric attenuation than 785 or 850 … 12 There is currently a misconception among designers and users of free space laser communication (lasercom) equipment that 1550 nm light suffers from less atmospheric attenuation than 785 or 850 nm light in all weather conditions. This misconception is based upon a published equation for atmospheric attenuation as a function of wavelength, which is used frequently in the free-space lasercom literature. In hazy weather (visibility > 2 km), the prediction of less atmospheric attenuation at 1550 nm is most likely true. However, in foggy weather (visibility < 500 m), it appears that the attenuation of laser light is independent of wavelength, ie. 785 nm, 850 nm, and 1550 nm are all attenuated equally by fog. This same wavelength independence is also observed in snow and rain. This observation is based on an extensive literature search, and from full Mie scattering calculations. A modification to the published equation describing the atmospheric attenuation of laser power, which more accurately describes the effects of fog, is offered. This observation of wavelength-independent attenuation in fog is important, because fog, heavy snow, and extreme rain are the only types of weather that are likely to disrupt short (< 500 m) lasercom links. Short lasercom links will be necessary to meet the high availability requirements of the telecommunications industry.

LED Based Indoor Visible Light Communications: State of the Art

2015-01-01

Dilukshan Karunatilaka , Fahad Zafar , Vineetha Kalavally +1 more

Visible Light Communication (VLC) is an emerging field in Optical Wireless Communication (OWC) which utilizes the superior modulation bandwidth of Light Emitting Diodes (LEDs) to transmit data. In modern day … Visible Light Communication (VLC) is an emerging field in Optical Wireless Communication (OWC) which utilizes the superior modulation bandwidth of Light Emitting Diodes (LEDs) to transmit data. In modern day communication systems, the most popular frequency band is Radio Frequency (RF) mainly due to little interference and good coverage. However, the rapidly dwindling RF spectrum along with increasing wireless network traffic has substantiated the need for greater bandwidth and spectral relief. By combining illumination and communication, VLC provides ubiquitous communication while addressing the shortfalls and limitations of RF communication. This paper provides a comprehensive survey on VLC with an emphasis on challenges faced in indoor applications over the period 1979-2014. VLC is compared with infrared (IR) and RF systems and the necessity for using this beneficial technology in communication systems is justified. The advantages of LEDs compared to traditional lighting technologies are discussed and comparison is done between different types of LEDs currently available. Modulation schemes and dimming techniques for indoor VLC are discussed in detail. Methods needed to improve VLC system performance such as filtering, equalization, compensation, and beamforming are also presented. The recent progress made by various research groups in this field is discussed along with the possible applications of this technology. Finally, the limitations of VLC as well as the probable future directions are presented.

Comparison of ACO-OFDM, DCO-OFDM and ADO-OFDM in IM/DD Systems

2013-01-21

Sarangi D. Dissanayake , Jean Armstrong

In this paper, three forms of orthogonal frequency division multiplexing (OFDM) designed for intensity modulated/direct detection (IM/DD) optical systems are compared. These are asymmetrically clipped optical OFDM (ACO-OFDM), DC biased … In this paper, three forms of orthogonal frequency division multiplexing (OFDM) designed for intensity modulated/direct detection (IM/DD) optical systems are compared. These are asymmetrically clipped optical OFDM (ACO-OFDM), DC biased optical OFDM (DCO-OFDM) and asymmetrically clipped DC biased optical OFDM (ADO-OFDM). ADO-OFDM is a new technique that combines aspects of ACO-OFDM and DCO-OFDM by simultaneously transmitting ACO-OFDM on the odd subcarriers and DCO-OFDM on the even subcarriers. The odd subcarriers are demodulated as in a conventional ACO-OFDM receiver and the even subcarriers are demodulated using a form of interference cancellation. ADO-OFDM is shown to be more optically power efficient than conventional ACO-OFDM and DCO-OFDM, for some bit rate/normalized bandwidths. It is also shown that by varying the proportion of optical power on the ACO-OFDM component, the DC bias level of DCO-OFDM and the constellations sent on the odd and even subcarriers, the optical power efficiency of ADO-OFDM can be changed.

1-Gb/s Transmission Over a Phosphorescent White LED by Using Rate-Adaptive Discrete Multitone Modulation

2012-07-26

Arslan Khalid , G. Cossu , R. Corsini +2 more

Light-emitting diodes (LEDs), which will be increasingly used in lighting technology, will also allow for distribution of broadband optical wireless signals. Visible-light communication (VLC) using white LEDs offers several advantages … Light-emitting diodes (LEDs), which will be increasingly used in lighting technology, will also allow for distribution of broadband optical wireless signals. Visible-light communication (VLC) using white LEDs offers several advantages over the RF-based wireless systems, i.e., license-free spectrum, low power consumption, and higher privacy. Mostly, optical wireless can provide much higher data rates. In this paper, we demonstrate a VLC system based on a white LED for indoor broadband wireless access. After investigating the nonlinear effects of the LED and the power amplifier, a data rate of 1 Gb/s has been achieved at the standard illuminance level, by using an optimized discrete multitone modulation technique and adaptive bit- and power-loading algorithms. The bit-error ratio of the received data was <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$1.5\cdot 10^{-3}$</tex></formula> , which is within the limit of common forward error correction (FEC) coding. These results twice the highest capacity that had been previously obtained.

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Visible light communication: opportunities, challenges and the path to market

2013-12-01

Aleksandar Jovičić , Junyi Li , Tom Richardson

Visible light communication is a potentially disruptive form of wireless communication that can supplement radio frequency communication and also uniquely enable novel mobile wireless device use cases. High data rate … Visible light communication is a potentially disruptive form of wireless communication that can supplement radio frequency communication and also uniquely enable novel mobile wireless device use cases. High data rate downlink communication in homes and offices and high accuracy indoor positioning in retail stores are two of the most compelling use cases of this promising new technology. Large-scale commercialization of visible light communication devices will depend on both the development of robust and efficient engineering solutions, and the execution of incremental commercialization strategies.

Urban optical wireless communication networks: the main challenges and possible solutions

2004-05-01

Debbie Kedar , Shlomi Arnon

Urban optical wireless communication (UOWC) is rapidly gaining popularity as an effective means of transferring data at high rates over short distances. The UOWC terminal includes an optical transmitter and … Urban optical wireless communication (UOWC) is rapidly gaining popularity as an effective means of transferring data at high rates over short distances. The UOWC terminal includes an optical transmitter and a receiver positioned, for example, on high-rise buildings separated by several hundred meters. Light beams propagating through the atmosphere carry the information from the transmitter to the receiver. UOWC boasts many advantages over its rivals. Notably, UOWC facilitates rapidly deployable, lightweight, high-capacity communication without licensing fees and tariffs. However, UOWC still faces many challenges, including how to improve communication performance in adverse weather conditions or during building sway. We present and evaluate some of the exciting new research approaches that have been suggested to deal with these issues, including optimization of telescope gain, new technologies for pointing systems, and solutions at the network level.

513 Mbit/s Visible Light Communications Link Based on DMT-Modulation of a White LED

2010-11-05

Jelena Vučić , Christoph Kottke , Stefan Nerreter +2 more

We report a visible-light wireless point-to-point communication link operating at 513 Mbit/s gross transmission rate (net Mbit/s). The bit-error ratio of the uncoded data was smaller than for an illumination … We report a visible-light wireless point-to-point communication link operating at 513 Mbit/s gross transmission rate (net Mbit/s). The bit-error ratio of the uncoded data was smaller than for an illumination level of lx. The link was based on a commercial thin-film high-power phosphorescent white LED, an avalanche photo diode, and off-line signal processing of discrete multitone signals. Quadrature-amplitude modulation, bit- and power-loading, as well as symmetrical clipping were successfully employed in pushing the gross transmission rate beyond 500 Mbit/s. Adaptation of the clipping level increased the data rate only by 2%, while simulations predicted an enhancement of 20%. Obstacles towards higher data rates as well as potential remedies are discussed. We predicted that data rates of over 1 Gbit/s can be achieved with the same setup and under the same experimental conditions if these obstacles are overcome.

Relay-assisted free-space optical communication

2008-12-01

Majid Safari , Murat Uysal

In this paper, we present relay-assisted transmission as a powerful fading mitigation tool for free-space optical systems operating in atmospheric turbulence channels. We study both serial (i.e., multi-hop transmission) and … In this paper, we present relay-assisted transmission as a powerful fading mitigation tool for free-space optical systems operating in atmospheric turbulence channels. We study both serial (i.e., multi-hop transmission) and parallel (i.e., cooperative diversity) relaying encoupled with amplify-and-forward and decode-and-forward modes. We consider an aggregated channel model which takes into account both path-loss and turbulence-induced log-normal fading. Since fading variance is distance-dependent in free-space optical systems, relay-assisted transmission takes advantage of the resulting shorter hops and yields significant performance improvements. We derive outage probability of the relaying schemes under consideration which are further confirmed through Monte-Carlo simulations. Our outage probability analysis demonstrates that an impressive performance improvement of 18.5 dB is possible with the use of a single relay at a target outage probability of 10 -6 .

Visible Light Communication, Networking, and Sensing: A Survey, Potential and Challenges

2015-01-01

Parth H. Pathak , Xiaotao Feng , Pengfei Hu +1 more

The solid-state lighting is revolutionizing the indoor illumination. Current incandescent and fluorescent lamps are being replaced by the LEDs at a rapid pace. Apart from extremely high energy efficiency, the … The solid-state lighting is revolutionizing the indoor illumination. Current incandescent and fluorescent lamps are being replaced by the LEDs at a rapid pace. Apart from extremely high energy efficiency, the LEDs have other advantages such as longer lifespan, lower heat generation, and improved color rendering without using harmful chemicals. One additional benefit of LEDs is that they are capable of switching to different light intensity at a very fast rate. This functionality has given rise to a novel communication technology (known as visible light communication-VLC) where LED luminaires can be used for high speed data transfer. This survey provides a technology overview and review of existing literature of visible light communication and sensing. This paper provides a detailed survey of 1) visible light communication system and characteristics of its various components such as transmitter and receiver; 2) physical layer properties of visible light communication channel, modulation methods, and MIMO techniques; 3) medium access techniques; 4) system design and programmable platforms; and 5) visible light sensing and application such as indoor localization, gesture recognition, screen-camera communication, and vehicular networking. We also outline important challenges that need to be addressed in order to design high-speed mobile networks using visible light communication.

Wireless in-house data communication via diffuse infrared radiation

1979-01-01

F. Gfeller , U. Bapst

A novel wireless broadcast/multi-access channel is described for flexibly interconnecting a cluster of data terminals located within the same room. The transmission medium is diffusively scattered infrared radiation at 950-nm … A novel wireless broadcast/multi-access channel is described for flexibly interconnecting a cluster of data terminals located within the same room. The transmission medium is diffusively scattered infrared radiation at 950-nm wavelength. Transmission is low-to-medium speed and the range up to 50 m. Theoretical analysis indicates that the time dispersion limits the transmission bandwidth of the system to 260 Mbit ċ m/s, but background noise produced by ambient daylight reduces the transmission speed below 1 Mbit/s. The transmission properties of the diffuse optical channel are analyzed, and experimental digital links for baseband PCM at 125 kbit/s and PSK 64 kbit/s are demonstrated.

IEEE 802.15.7 visible light communication: modulation schemes and dimming support

2012-03-01

Sridhar Rajagopal , Richard D. Roberts , Sang‐Kyu Lim

Visible light communication refers to shortrange optical wireless communication using visible light spectrum from 380 to 780 nm. Enabled by recent advances in LED technology, IEEE 802.15.7 supports high-data-rate visible … Visible light communication refers to shortrange optical wireless communication using visible light spectrum from 380 to 780 nm. Enabled by recent advances in LED technology, IEEE 802.15.7 supports high-data-rate visible light communication up to 96 Mb/s by fast modulation of optical light sources which may be dimmed during their operation. IEEE 802.15.7 provides dimming adaptable mechanisms for flicker-free high-data-rate visible light communication.

Wireless infrared communications

1997-01-01

Joseph M. Kahn , John R. Barry

The use of infrared radiation as a medium for high-speed short-range wireless digital communication is discussed. Available infrared links and local-area networks are described. Advantages and drawbacks of the infrared … The use of infrared radiation as a medium for high-speed short-range wireless digital communication is discussed. Available infrared links and local-area networks are described. Advantages and drawbacks of the infrared medium are compared to those of radio and microwave media. The physical characteristics of infrared channels using intensity modulation with direct detection (IM/DD) are presented including path losses and multipath responses. Natural and artificial ambient infrared noise sources are characterized. Strategies for designs of transmitter and receivers that maximize link signal-to-noise ratio (SNR) are described. Several modification formats are discussed in detail, including on-off keying (OOK) pulse-position modulation (PPM), and subcarrier modulation. The performance of these techniques in the presence of multipath distortion is quantified. Techniques for multiplexing the transmissions of different users are reviewed. The performance of an experimental 50-Mb/s on-off-keyed diffuse infrared link is described.

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A 3-Gb/s Single-LED OFDM-Based Wireless VLC Link Using a Gallium Nitride $\mu{\rm LED}$

2014-01-31

Dobroslav Tsonev , Hyunchae Chun , Sujan Rajbhandari +7 more

This letter presents a visible light communication (VLC) system based on a single 50- μm gallium nitride light emitting diode (LED). A device of this size exhibits a 3-dB modulation … This letter presents a visible light communication (VLC) system based on a single 50- μm gallium nitride light emitting diode (LED). A device of this size exhibits a 3-dB modulation bandwidth of at least 60 MHz - significantly higher than commercially available white lighting LEDs. Orthogonal frequency division multiplexing is employed as a modulation scheme. This enables the limited modulation bandwidth of the device to be fully used. Pre- and postequalization techniques, as well as adaptive data loading, are successfully applied to achieve a demonstration of wireless communication at speeds exceeding 3 Gb/s. To date, this is the fastest wireless VLC system using a single LED.

Free-space optical communication through atmospheric turbulence channels

2002-08-01

Xiaoming Zhu , Joseph M. Kahn

In free-space optical communication links, atmospheric turbulence causes fluctuations in both the intensity and the phase of the received light signal, impairing link performance. We describe several communication techniques to … In free-space optical communication links, atmospheric turbulence causes fluctuations in both the intensity and the phase of the received light signal, impairing link performance. We describe several communication techniques to mitigate turbulence-induced intensity fluctuations, i.e., signal fading. These techniques are applicable in the regime in which the receiver aperture is smaller than the correlation length of fading and the observation interval is shorter than the correlation time of fading. We assume that the receiver has no knowledge of the instantaneous fading state. When the receiver knows only the marginal statistics of the fading, a symbol-by-symbol ML detector can be used to improve detection performance. If the receiver has knowledge of the joint temporal statistics of the fading, maximum-likelihood sequence detection (MLSD) can be employed, yielding a further performance improvement, but at the cost of very high complexity. Spatial diversity reception with multiple receivers can also be used to overcome turbulence-induced fading. We describe the use of ML detection in spatial diversity reception to reduce the diversity gain penalty caused by correlation between the fading at different receivers.

Optical wireless links with spatial diversity over strong atmospheric turbulence channels

2009-02-01

Theodoros A. Tsiftsis , Harilaos G. Sandalidis , George K. Karagiannidis +1 more

Optical wireless, also known as free-space optics, has received much attention in recent years as a cost-effective, license-free and wide-bandwidth access technique for high data rates applications. The performance of … Optical wireless, also known as free-space optics, has received much attention in recent years as a cost-effective, license-free and wide-bandwidth access technique for high data rates applications. The performance of free-space optical (FSO) communication, however, severely suffers from turbulence-induced fading caused by atmospheric conditions. Multiple laser transmitters and/or receivers can be placed at both ends to mitigate the turbulence fading and exploit the advantages of spatial diversity. Spatial diversity is particularly crucial for strong turbulence channels in which single-input single-output (SISO) link performs extremely poor. Atmospheric-induced strong turbulence fading in outdoor FSO systems can be modeled as a multiplicative random process which follows the K distribution. In this paper, we investigate the error rate performance of FSO systems for K-distributed atmospheric turbulence channels and discuss potential advantages of spatial diversity deployments at the transmitter and/or receiver. We further present efficient approximated closed-form expressions for the average bit-error rate (BER) of single-input multiple-output (SIMO) FSO systems. These analytical tools are reliable alternatives to time-consuming Monte Carlo simulation of FSO systems where BER targets as low as 10 -9 are typically aimed to achieve.

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Broadband Information Broadcasting Using LED-Based Interior Lighting

2008-12-01

Jelena Grubor , S. Randel , Klaus-Dieter Langer +1 more

Emergence of white-light LEDs allows the combination of lighting and information broadcast functionality in one optical source. We investigate analytically and by Monte Carlo simulations feasible data transmission rates in … Emergence of white-light LEDs allows the combination of lighting and information broadcast functionality in one optical source. We investigate analytically and by Monte Carlo simulations feasible data transmission rates in a moderate-size office room, where we assume illumination conforming to standards and the use of commercially available LEDs and photodiodes. The performances of systems relying on baseband [i.e., pulse-amplitude modulation (PAM)] and discrete multitone (DMT) transmission show that data rates of more than 100 Mbit/s can be expected despite the rather low bandwidth of the system.

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Indoor optical wireless communication: potential and state-of-the-art

2011-09-01

Hany Elgala , Raed Mesleh , Harald Haas

In recent years, interest in optical wireless (OW) as a promising complementary technology for RF technology has gained new momentum fueled by significant deployments in solid state lighting technology. This … In recent years, interest in optical wireless (OW) as a promising complementary technology for RF technology has gained new momentum fueled by significant deployments in solid state lighting technology. This article aims at reviewing and summarizing recent advancements in OW communication, with the main focus on indoor deployment scenarios. This includes a discussion of challenges, potential applications, state of the art, and prospects. Related issues covered in this article are duplex transmission, multiple access, MAC protocols, and link capacity improvements.

Simulation of multipath impulse response for indoor wireless optical channels

1993-04-01

John R. Barry , Joseph M. Kahn , William J. Krause +2 more

A recursive method for evaluating the impulse response of an indoor free-space optical channel with Lambertian reflectors is presented. The method, which accounts for multiple reflections of any order, enables … A recursive method for evaluating the impulse response of an indoor free-space optical channel with Lambertian reflectors is presented. The method, which accounts for multiple reflections of any order, enables accurate analysis of the effects of multipath dispersion on high-speed indoor optical communication systems. A simple algorithm for computer implementation of the technique and computer simulation results for both line-of-sight and diffuse transmitter configurations are also presented. In both cases, it is shown that reflections of multiple order are a significant source of intersymbol interference. Experimental measurements of optical multipath, which help verify the accuracy of the simulations, are discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>

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Outage Capacity Optimization for Free-Space Optical Links With Pointing Errors

2007-07-01

Ahmed A. Farid , Steve Hranilovic

We investigate the performance and design of free-space optical (FSO) communication links over slow fading channels from an information theory perspective. A statistical model for the optical intensity fluctuation at … We investigate the performance and design of free-space optical (FSO) communication links over slow fading channels from an information theory perspective. A statistical model for the optical intensity fluctuation at the receiver due to the combined effects of atmospheric turbulence and pointing errors is derived. Unlike earlier work, our model considers the effect of beam width, detector size, and jitter variance explicitly. Expressions for the outage probability are derived for a variety of atmospheric conditions. For given weather and misalignment conditions, the beam width is optimized to maximize the channel capacity subject to outage. Large gains in achievable rate are realized versus using a nominal beam width. In light fog, by optimizing the beam width, the achievable rate is increased by 80% over the nominal beam width at an outage probability of 10 -5 . Well-known error control codes are then applied to the channel and shown to realize much of the achievable gains.

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Comparison of Asymmetrically Clipped Optical OFDM and DC-Biased Optical OFDM in AWGN

2008-05-01

Jean Armstrong , Brendon J. C. Schmidt

We present theoretical and simulation results for the performance of asymmetrically-clipped optical OFDM (ACO-OFDM) and DC-biased optical OFDM (DCO-OFDM) in AWGN for intensity-modulated direct-detection systems. Constellations from 4 QAM to … We present theoretical and simulation results for the performance of asymmetrically-clipped optical OFDM (ACO-OFDM) and DC-biased optical OFDM (DCO-OFDM) in AWGN for intensity-modulated direct-detection systems. Constellations from 4 QAM to 1024 QAM are considered. For DCO-OFDM, the optimum bias depends on the constellation size which limits its performance in adaptive systems. ACO-OFDM requires less optical power for a given data rate than DCO-OFDM for all but the largest constellations and is better suited to adaptive systems as the same structure is optimum for all constellations.

Ultraviolet Communications: Potential and State-Of-The-Art

2008-05-01

Zhengyuan Xu , Brian M. Sadler

Motivated by the recent and rapid developments in deep ultraviolet LEDs, solar blind ultraviolet filters, and detectors, this article reviews wireless UV technology used for communications and sensing in either … Motivated by the recent and rapid developments in deep ultraviolet LEDs, solar blind ultraviolet filters, and detectors, this article reviews wireless UV technology used for communications and sensing in either line-of-sight or non-line-of-sight channel conditions. We present the state-of-the-art of associated systems and their components and discuss related issues including communication link characterization, channel modeling, and link capacity study, as well as transceiver design, link duplexing, multiple access, and networking. We also envision applications in the commercial and military sectors.

Fundamental analysis for visible-light communication system using LED lights

2004-02-01

Toshihiko Komine , Masaki Nakagawa

White LED offers advantageous properties such as high brightness, reliability, lower power consumption and long lifetime. White LEDs are expected to serve in the next generation of lamps. An indoor … White LED offers advantageous properties such as high brightness, reliability, lower power consumption and long lifetime. White LEDs are expected to serve in the next generation of lamps. An indoor visible-light communication system utilizing white LED lights has been proposed from our laboratory. In the proposed system, these devices are used not only for illuminating rooms but also for an optical wireless communication system. Generally, plural lights are installed in our room. So, their optical path difference must be considered. In this paper, we discuss about the influence of interference and reflection. Based on numerical analyses, we show that the system is expected to be the indoor communication of the next generation.

Free-Space Optical Communications

2006-12-01

Vincent Chan

With recent successes of laboratory, inatmosphere, and space demonstrations of free-space optical communications, there is no doubt that the technology is ready for operational deployment. While these successes have shown … With recent successes of laboratory, inatmosphere, and space demonstrations of free-space optical communications, there is no doubt that the technology is ready for operational deployment. While these successes have shown that there are no laws of physics against such systems, their estimated system costs are still much too high for serious considerations. Two types of development can reduce the cost dramatically. The first is via the improvement of physical-link communication efficiency by an order of magnitude using photon-counting receivers for vacuum channels, system complexity, weight, and power for space systems can be greatly reduced. The second is through the use of coherent systems in links where clear-air turbulence impairs communication efficiency, and in multiple access applications where coherent processing can reduce the level of interference, significant reduction in system costs can be realized

Indoor Channel Characteristics for Visible Light Communications

2011-01-07

Kwonhyung Lee , Hyuncheol Park , John R. Barry

In this letter, we present indoor multipath dispersion characteristics for visible light communications (VLC). Since the VLC uses a wide spectrum between 380 nm and 780 nm, the conventional narrowband … In this letter, we present indoor multipath dispersion characteristics for visible light communications (VLC). Since the VLC uses a wide spectrum between 380 nm and 780 nm, the conventional narrowband model for infrared may not apply. We generalize the Barry's model by including wavelength-dependent white LED characteristics and spectral reflectance of indoor reflectors. We perform a computer simulation to compare the power delay profile of the VLC with that of infrared communications. From our studies, we show that the VLC provides a larger transmission bandwidth than infrared communications.

High data rate multiple input multiple output (MIMO) optical wireless communications using white led lighting

2009-12-01

Lubin Zeng , Dominic O’Brien , Hoa Le Minh +5 more

Solid-state lighting is a rapidly growing area of research and applications, due to the reliability and predicted high efficiency of these devices. The white LED sources that are typically used … Solid-state lighting is a rapidly growing area of research and applications, due to the reliability and predicted high efficiency of these devices. The white LED sources that are typically used for general illumination can also be used for data transmission, and Visible Light Communications (VLC) is a rapidly growing area of research. One of the key challenges is the limited modulation bandwidth of sources, typically several MHz. However, as a room or coverage space would typically be illuminated by an array of LEDs there is the potential for parallel data transmission, and using optical MIMO techniques is potentially attractive for achieving high data rates. In this paper we investigate non-imaging and imaging MIMO approaches: a non-imaging optical MIMO system does not perform properly at all receiver positions due to symmetry, but an imaging based system can operate under all foreseeable circumstances. Simulations show such systems can operate at several hundred Mbit/s, and up to Gbit/s in many circumstances.

BER Performance of Free-Space Optical Transmission with Spatial Diversity

2007-08-01

S.M. Navidpour , Murat Uysal , M. Kavehrad

Free space optical (FSO) communications is a cost-effective and high bandwidth access technique, which has been receiving growing attention with recent commercialization successes. A major impairment in FSO links is … Free space optical (FSO) communications is a cost-effective and high bandwidth access technique, which has been receiving growing attention with recent commercialization successes. A major impairment in FSO links is the turbulence- induced fading which severely degrades the link performance. To mitigate turbulence-induced fading and, therefore, to improve the error rate performance, spatial diversity can be used over FSO links which involves the deployment of multiple laser transmitters/receivers. In this paper, we investigate the bit error rate (BER) performance of FSO links with spatial diversity over log- normal atmospheric turbulence fading channels, assuming both independent and correlated channels among transmitter/receiver apertures. Our analytical derivations build upon an approximation to the sum of correlated log-normal random variables. The derived BER expressions quantify the effect of spatial diversity and possible spatial correlations in a log-normal channel.

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Atmospheric turbulence effects on a partially coherent Gaussian beam: implications for free-space laser communication

2002-09-01

Jennifer C. Ricklin , Frederic M. Davidson

A partially coherent quasi-monochromatic Gaussian laser beam propagating in atmospheric turbulence is examined by using a derived analytic expression for the cross-spectral density function. Expressions for average intensity, beam size, … A partially coherent quasi-monochromatic Gaussian laser beam propagating in atmospheric turbulence is examined by using a derived analytic expression for the cross-spectral density function. Expressions for average intensity, beam size, phase front radius of curvature, and wave-front coherence length are obtained from the cross-spectral density function. These results provide a model for a free-space laser transmitter with a phase diffuser used to reduce pointing errors.

Error rate performance analysis of coded free-space optical links over gamma-gamma atmospheric turbulence channels

2006-06-01

Murat Uysal , Jing Li , Meng Yu

Error control coding can be used over free-space optical (FSO) links to mitigate turbulence-induced fading. In this paper, we derive error performance bounds for coded FSO communication systems operating over … Error control coding can be used over free-space optical (FSO) links to mitigate turbulence-induced fading. In this paper, we derive error performance bounds for coded FSO communication systems operating over atmospheric turbulence channels, considering the recently introduced gamma-gamma turbulence model. We derive a pairwise error probability (PEP) expression and then apply the transfer function technique in conjunction with the derived PEP to obtain upper bounds on the bit error rate. Simulation results are further demonstrated to confirm the analytical results.

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BPSK Subcarrier Intensity Modulated Free-Space Optical Communications in Atmospheric Turbulence

2009-04-01

Wasiu O. Popoola , Zabih Ghassemlooy

Free-space optical communications (FSO) propagated over a clear atmosphere suffers from irradiance fluctuation caused by small but random atmospheric temperature fluctuations. This results in decreased signal-to-noise ratio (SNR) and consequently … Free-space optical communications (FSO) propagated over a clear atmosphere suffers from irradiance fluctuation caused by small but random atmospheric temperature fluctuations. This results in decreased signal-to-noise ratio (SNR) and consequently impaired performance. In this paper, the error performance of the FSO using a subcarrier intensity modulation (SIM) based on a binary phase shift keying (BPSK) scheme in a clear but turbulent atmosphere is presented. To evaluate the system error performance in turbulence regimes from weak to strong, the probability density function (pdf) of the received irradiance after traversing the atmosphere is modelled using the gamma-gamma distribution while the negative exponential distribution is used to model turbulence in the saturation region and beyond. The effect of turbulence induced irradiance fluctuation is mitigated using spatial diversity at the receiver. With reference to the single photodetector case, up to 12 dB gain in the electrical SNR is predicted with two direct detection PIN photodetectors in strong atmospheric turbulence.

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What is LiFi?

2015-12-17

Harald Haas , Liang Yin , Yunlu Wang +1 more

This paper attempts to clarify the difference between visible light communication (VLC) and light-fidelity (LiFi). In particular, it will show how LiFi takes VLC further by using light emitting diodes … This paper attempts to clarify the difference between visible light communication (VLC) and light-fidelity (LiFi). In particular, it will show how LiFi takes VLC further by using light emitting diodes (LEDs) to realise fully networked wireless systems. Synergies are harnessed as luminaries become LiFi attocells resulting in enhanced wireless capacity providing the necessary connectivity to realise the Internet-of-Things, and contributing to the key performance indicators for the fifth generation of cellular systems (5G) and beyond. It covers all of the key research areas from LiFi components to hybrid LiFi/wireless fidelity (WiFi) networks to illustrate that LiFi attocells are not a theoretical concept any more, but at the point of real-world deployment.

Visible light communication: Applications, architecture, standardization and research challenges

2016-08-15

Latif U. Khan

The Radio Frequency (RF) communication suffers from interference and high latency issues. Along with this, RF communication requires a separate setup for transmission and reception of RF waves. Overcoming the … The Radio Frequency (RF) communication suffers from interference and high latency issues. Along with this, RF communication requires a separate setup for transmission and reception of RF waves. Overcoming the above limitations, Visible Light Communication (VLC) is a preferred communication technique because of its high bandwidth and immunity to interference from electromagnetic sources. The revolution in the field of solid state lighting leads to the replacement of florescent lamps by Light Emitting Diodes (LEDs) which further motivates the usage of VLC. This paper presents a survey of the potential applications, architecture, modulation techniques, standardization and research challenges in VLC.

Optical Communication in Space: Challenges and Mitigation Techniques

2016-08-26

Hemani Kaushal , Georges Kaddoum

In recent years, free space optical communication has gained significant importance owing to its unique features: large bandwidth, license-free spectrum, high data rate, easy and quick deployability, less power and … In recent years, free space optical communication has gained significant importance owing to its unique features: large bandwidth, license-free spectrum, high data rate, easy and quick deployability, less power and low mass requirements. FSO communication uses the optical carrier in the near infrared band to establish either terrestrial links within the Earth's atmosphere or inter-satellite or deep space links or ground-to-satellite or satellite-to-ground links. However, despite the great potential of FSO communication, its performance is limited by the adverse effects viz., absorption, scattering, and turbulence of the atmospheric channel. This paper presents a comprehensive survey on various challenges faced by FSO communication system for ground-to-satellite or satellite-to-ground and inter-satellite links. It also provides details of various performance mitigation techniques in order to have high link availability and reliability. The first part of the paper will focus on various types of impairments that pose a serious challenge to the performance of optical communication system for ground-to-satellite or satellite-to-ground and inter-satellite links. The latter part of the paper will provide the reader with an exhaustive review of various techniques both at physical layer as well as at the other layers i.e., link, network or transport layer to combat the adverse effects of the atmosphere. It also uniquely presents a recently developed technique using orbital angular momentum for utilizing the high capacity advantage of the optical carrier in case of space-based and near-Earth optical communication links. This survey provides the reader with comprehensive details on the use of space-based optical backhaul links in order to provide high-capacity and low-cost backhaul solutions.

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A Comparative Survey of Optical Wireless Technologies: Architectures and Applications

2018-01-01

Mostafa Zaman Chowdhury , Md. Tanvir Hossan , Amirul Islam +1 more

New high-data-rate multimedia services and applications are evolving continuously and exponentially increasing the demand for wireless capacity of fifth-generation (5G) and beyond. The existing radio frequency (RF) communication spectrum is … New high-data-rate multimedia services and applications are evolving continuously and exponentially increasing the demand for wireless capacity of fifth-generation (5G) and beyond. The existing radio frequency (RF) communication spectrum is insufficient to meet the demands of future high-datarate 5G services. Optical wireless communication (OWC), which uses an ultra-wide range of unregulated spectrum, has emerged as a promising solution to overcome the RF spectrum crisis. It has attracted growing research interest worldwide in the last decade for indoor and outdoor applications. OWC offloads huge data traffic applications from RF networks. A 100 Gb/s data rate has already been demonstrated through OWC. It offers services indoors as well as outdoors, and communication distances range from several nm to more than 10000 km. This paper provides a technology overview and a review on optical wireless technologies, such as visible light communication, light fidelity, optical camera communication, free space optical communication, and light detection and ranging. We survey the key technologies for understanding OWC and present state-of-the-art criteria in aspects, such as classification, spectrum use, architecture, and applications. The key contribution of this paper is to clarify the differences among different promising optical wireless technologies and between these technologies and their corresponding similar existing RF technologies.

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A Survey of Positioning Systems Using Visible LED Lights

2018-01-01

Yuan Zhuang , Luchi Hua , Longning Qi +6 more

As Global Positioning System (GPS) cannot provide satisfying performance in indoor environments, indoor positioning technology, which utilizes indoor wireless signals instead of GPS signals, has grown rapidly in recent years. … As Global Positioning System (GPS) cannot provide satisfying performance in indoor environments, indoor positioning technology, which utilizes indoor wireless signals instead of GPS signals, has grown rapidly in recent years. Meanwhile, visible light communication (VLC) using light devices such as light emitting diodes (LEDs) has been deemed to be a promising candidate in the heterogeneous wireless networks that may collaborate with radio frequencies (RF) wireless networks. In particular, light-fidelity has a great potential for deployment in future indoor environments because of its high throughput and security advantages. This paper provides a comprehensive study of a novel positioning technology based on visible white LED lights, which has attracted much attention from both academia and industry. The essential characteristics and principles of this system are deeply discussed, and relevant positioning algorithms and designs are classified and elaborated. This paper undertakes a thorough investigation into current LED-based indoor positioning systems and compares their performance through many aspects, such as test environment, accuracy, and cost. It presents indoor hybrid positioning systems among VLC and other systems (e.g., inertial sensors and RF systems). We also review and classify outdoor VLC positioning applications for the first time. Finally, this paper surveys major advances as well as open issues, challenges, and future research directions in VLC positioning systems.

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6G Vision and Requirements: Is There Any Need for Beyond 5G?

2018-07-18

Klaus David , Hendrik Berndt

To address the question in the subtitle of this article, we start by discussing earlier mobile communication systems, beginning with the first analog wireless cellular standards, then moving on to … To address the question in the subtitle of this article, we start by discussing earlier mobile communication systems, beginning with the first analog wireless cellular standards, then moving on to second generation (2G) [or Global System for Mobile Communications (GSM)], passing third generation (3G) and fourth generation (4G), and proceeding to fifth generation (5G). First, we present each generation's key achievements in terms of user services, each generation's technologyrelated factors of success (called innovations) as well as its relation to regulation, and each generation's potential deficiencies.

Visible Light Communication: Concepts, Applications and Challenges

2019-01-01

Luiz Eduardo Mendes Matheus , Alex Borges Vieira , Luiz F. M. Vieira +2 more

During the last decade, the exponential growth of mobile devices and wireless services created a huge demand for radio frequency-based technologies. Meanwhile, the lighting industry has been revolutionized due to … During the last decade, the exponential growth of mobile devices and wireless services created a huge demand for radio frequency-based technologies. Meanwhile, the lighting industry has been revolutionized due to the popularization of LED light bulbs, which are more economical and efficient. In that context, visible light communication (VLC) is a disruptive technology based on LEDs that offers a free spectrum and high data rate, which can potentially serve as a complementary technology to the current radio frequency standards. In this paper, we present a comprehensive state-of-the-art survey of VLC, as well as the main concepts and challenges related to this emergent area. We overview VLC technology, from its physical aspects and communication architecture to its main applications and research challenges. Finally, we present the main research platforms available today, along with a deep analysis of the system design and future directions in the field.

FSO-Based Vertical Backhaul/Fronthaul Framework for 5G+ Wireless Networks

2018-01-01

Mohamed Alzenad , Muhammad Zeeshan Shakir , Halim Yanıkömeroğlu +1 more

The presence of a super high rate, but also cost-efficient, easy-to-deploy, and scalable, backhaul/fronthaul framework, is essential in the upcoming 5G wireless networks and beyond. Motivated by the mounting interest … The presence of a super high rate, but also cost-efficient, easy-to-deploy, and scalable, backhaul/fronthaul framework, is essential in the upcoming 5G wireless networks and beyond. Motivated by the mounting interest in unmanned flying platforms of various types, including UAVs, drones, balloons, and HAPs/MAPs/LAPs, which we refer to as networked flying platforms (NFPs), for providing communications services, and by the recent advances in free space optics (FSO), this article investigates the feasibility of a novel vertical backhaul/fronthaul framework where the NFPs transport the backhaul/fronthaul traffic between the access and core networks via point-to- point FSO links. The performance of the proposed innovative approach is investigated under different weather conditions and a broad range of system parameters. Simulation results demonstrate that the FSO-based vertical backhaul/fronthaul framework can offer data rates higher than the baseline alternatives, and thus can be considered a promising solution to the emerging backhaul/fronthaul requirements of the 5G+ wireless networks, particularly in the presence of ultra-dense heterogeneous small cells. This article also presents the challenges that accompany such a novel framework and provides some key ideas toward overcoming these challenges.

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6G: The Next Frontier: From Holographic Messaging to Artificial Intelligence Using Subterahertz and Visible Light Communication

2019-08-08

Emilio Calvanese Strinati , Sergio Barbarossa , José Luis González +4 more

With its ability to provide a single platform enabling a variety of services, such as enhanced mobile broadband communications, virtual reality, automated driving, and the Internet of Things, 5G represents … With its ability to provide a single platform enabling a variety of services, such as enhanced mobile broadband communications, virtual reality, automated driving, and the Internet of Things, 5G represents a breakthrough in the design of communication networks. Nevertheless, considering the increasing requests for new services and predicting the development of new technologies within a decade, it is already possible to envision the need to move beyond 5G and design a new architecture incorporating innovative technologies to satisfy new needs at both the individual and societal levels.

Visible Light Communication in 6G: Advances, Challenges, and Prospects

2020-09-29

Nan Chi , Yingjun Zhou , Yiran Wei +1 more

6G networks are expected to provide extremely high capacity and satisfy emerging applications, but current frequency bands may not be sufficient. Moreover, 6G will provide superior coverage by integrating space/air/underwater … 6G networks are expected to provide extremely high capacity and satisfy emerging applications, but current frequency bands may not be sufficient. Moreover, 6G will provide superior coverage by integrating space/air/underwater networks with terrestrial networks, given that traditional wireless communications are not able to provide high-speed data rates for nonterrestrial networks. Visible light communication (VLC) is a high-speed communication technique with an unlicensed frequency range of 400-800 THz and can be adopted as an alternative approach to solving these problems. In this article, we present the prospects and challenges of VLC in 6G in conjunction with its advances in high-speed transmissions. Recent hot research interests, including new materials and devices, advanced modulation, underwater VLC (UVLC), and signal processing based on machine learning, are also discussed. It is envisaged that VLC will become an indispensable part of 6G given its high-speed transmission advantages and will cooperate with other communication methods to benefit our daily lives.

Optical Wireless Communications

2019-04-30

Zabih Ghassemlooy , Wasiu O. Popoola , Sujan Rajbhandari

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Advanced Optical Wireless Communication Systems

2012-05-24

Shlomi Arnon , John R. Barry , George K. Karagiannidis +2 more

Optical wireless communications is a dynamic area of research and development. Combining fundamental theory with a broad overview, this book is an ideal reference for anyone working in the field, … Optical wireless communications is a dynamic area of research and development. Combining fundamental theory with a broad overview, this book is an ideal reference for anyone working in the field, as well as a valuable guide for self-study. It begins by describing important issues in optical wireless theory, including coding and modulation techniques for optical wireless, wireless optical CDMA communication systems, equalization and Markov chains in cloud channels and optical MIMO systems, as well as explaining key issues in information theory for optical wireless channels. The next section describes unique channels that could be found in optical wireless applications, such as NLOS UV atmospheric scattering channels, underwater communication links and a combination of hybrid RF/optical wireless systems. The final section describes applications of optical wireless technology, such as quantum encryption, visible light communication, IR links and sensor networks, with step-by-step guidelines to help reduce design time and cost.

OFDM for Optical Communications

2010-01-01

William Shieh , Ivan B. Djordjević

Mobility-Aware and Preference-Driven Collaborative Edge Caching in SDN-enabled VLC Networks

2025-06-25

Vuai Ali Kombo , Yulinar Adnan , Omar Haji Kombo +2 more | Journal of Control Engineering and Applied Informatics

Reliable Optical Wireless Communication in Underwater Sensor Networks Using GRO Based DCO-OFDM

2025-06-25

Shravan Kumar , Annapurna Gummadi , U. Hariharan +2 more | Wireless Personal Communications

A systematic review of intelligent reflecting surface aided non-orthogonal multiple access beamforming-based free space optical communication systems

2025-06-24

Batool Natiq , Lwaa Faisal Abdulameer | Al-Qadisiyah Journal for Engineering Sciences

The intelligent reflecting surfaces (IRSs) that support non-orthogonal multiple access (NOMA), and using beamforming techniques in free space optical (FSO), are systematically reviewed in this study. The IRS improves the … The intelligent reflecting surfaces (IRSs) that support non-orthogonal multiple access (NOMA), and using beamforming techniques in free space optical (FSO), are systematically reviewed in this study. The IRS improves the spectral efficiency and connection by guiding channel users more efficiently through reconfigurable reflecting elements. This enhancement makes it easier to apply NOMA even when the original channels are not aligned. The study emphasizes how hardware limitations like phase shifters with poor precision affect performance. A thorough analysis of previous studies on IRS varieties, beamforming strategies, and multiple access strategies is given. Additionally, the research gaps and potential future paths are also detailed. Background information on IRS types is one of the key contributions. Another major contribution is highlighting the advantages of combining IRS with beamforming and multiple access strategies in FSO communication systems.

Transmission of LG Modes in High-Capacity 16 × 10 Gbps FSO System Using FBG Sensors Under Different Channel Scenarios

2025-06-24

Meet Kumari , Satyendra Kumar Mishra | Micromachines

Free space optics (FSO) aims to perform as one of the best optical wireless channels to design a reliable, flexible, and cost-effective communication system. In FSO systems, mode-division multiplexing (MDM) … Free space optics (FSO) aims to perform as one of the best optical wireless channels to design a reliable, flexible, and cost-effective communication system. In FSO systems, mode-division multiplexing (MDM) transmission is a proven technique to expand transmission capacity per communication link. Thus, a 16 × 10 Gbps MDM-FSO system using fiber Bragg grating (FBG) sensors for the coexistence of communication and sensing, exploiting FSO links to transmit distinct Laguerre-Gaussian (LG) beams at a 1000–1900 m range, is proposed. The results illustrate that the system can transmit higher-order LG beams with sensor temperatures of 20–120 °C over a 1500 m range under clear air, drizzle, and moderate haze weather. Also, an improved performance is achieved in gamma–gamma compared to the log-normal distribution model for 10−6–10−2.5 index modulation under weak-to-strong turbulence. The proposed system is capable of offering a high optical signal-to-noise ratio (OSNR) and gain of 113.39 and 15.43 dB, respectively, at an aggregate data rate of 160 Gbps under different atmospheric scenarios. Moreover, the proposed system achieves better system performance compared to existing works.

Increasing capacity of intra-datacenter communications using a novel combination of DQPSK and PAM-4 modulation formats

2025-06-24

Yaohua Yi , Salman Ghafoor , Abdullah G. Alharbi +2 more | Optical Fiber Technology

Evaluation of daylight background noise for satellite-to-ground free-space optical communication during daytime operation

2025-06-24

Heesuk Jang , Hajun Song , Hansol Jang | Photonics Research

Three-dimensional 32QAM constellation design based on lattice in visible light communication systems

2025-06-24

Xinyue Guo , Ruijia Xu | Optics Letters

Performance analysis of UAV-FSO system over atmospheric conditions with pointing errors

2025-06-24

Yamuna Tumma , Vinod Kiran Kappala | Optical and Quantum Electronics

Performance Analysis of Space-to-Ground Downlink for Polarization Shift Keying Optical Communications with a Gaussian-Schell Model Beam

2025-06-24

Jiajie Wu , Yuwei Zhang , Qingyan Li +2 more | Photonics

Free-space optical communication has emerged as a pivotal technology for space-to-ground downlinks; however, signal degradation caused by atmospheric turbulence continues to pose a significant challenge. In this study, a model … Free-space optical communication has emerged as a pivotal technology for space-to-ground downlinks; however, signal degradation caused by atmospheric turbulence continues to pose a significant challenge. In this study, a model for the polarization transmission characteristics of a Gaussian-Schell model (GSM) beam in downlink was established, and conditions sufficient for maintaining the polarization transmission characteristics were derived. The impact of the source spatial coherence on the performance of optical communication systems using circular polarization shift keying (CPolSK) modulation was investigated. Additionally, models for the probability density distribution and scintillation index of the optical intensity under atmospheric turbulence were developed along with a bit error rate model for the optical communication system. The effects of the laser spatial coherence on these models were also analyzed. The results indicate that the optimal performance in the turbulent downlink is achieved with fully coherent light, where the GSM-beam-based CPolSK-modulated system demonstrates a reduction of 1.51 dB in the required power compared to that of an on–off keying system. The implications of this study suggest that optimizing spatial coherence could significantly enhance the reliability of space-to-ground communication systems under atmospheric disturbances.

Turbulence-resilient adaptive modulation and diversity coding for DWDM-based hybrid MIMO-RF/FSO systems

2025-06-23

Ebrahim E. Elsayed , Mohamed Yakout , Ahmed S. Samra | Journal of Optical Communications

Abstract This research introduces an enhanced transmission framework for hybrid multiple-input multiple-output (MIMO) and dense wavelength-division multiplexing (DWDM) radio frequency/free-space optical (RF/FSO) communication systems, utilizing diversity coding techniques to combat … Abstract This research introduces an enhanced transmission framework for hybrid multiple-input multiple-output (MIMO) and dense wavelength-division multiplexing (DWDM) radio frequency/free-space optical (RF/FSO) communication systems, utilizing diversity coding techniques to combat turbulence-induced signal degradation. The proposed system achieves an aggregate data rate of 20 gigabits per second (Gbps) through eight channels operating at 2.5 Gbps each over a 1,500-meter (m) link, with comprehensive performance evaluation of bit error rate (BER), outage probability (OP), and signal-to-noise ratio (SNR) across three primary diversity combining methods: maximum ratio combining (MRC), selection combining (SC), and equal-gain combining (EGC). Analysis confirms the superior performance of Alamouti coding (AC), space-time coding (STC), space-time block coding (STBC), space-time trellis coding (STTC), orthogonal STBC (O-STBC), and quasi-orthogonal STBC (QO-STBC) in hybrid DWDM-MIMO-RF/FSO networks, particularly in reducing mean-square error while improving turbulence resilience. Simulation results demonstrate that QO-STBC and STTC implementations combined with MRC or SC significantly enhance BER, SNR, and outage characteristics in MIMO-DWDM FSO systems, with MRC showing better performance than both SC and EGC in minimizing BER and OP. Furthermore, numerical analysis reveals that DWDM-augmented QO-STBC/STTC in RF/FSO links reduces power penalties across BER thresholds under diverse turbulence conditions (weak, moderate, and strong), surpassing non-DWDM FSO configurations.

High Refractive Index Metamaterial-based Radiation Aggregation for Gain Enhancement

2025-06-23

Mohammad Lutful Hakim , Mohammad Tariqul Islam , Touhidul Alam | CRC Press eBooks

Beyond 100 m Range Mini-LED-Based Visible Light Communication System

2025-06-20

Zhijian Lv , S.‐N. Wu , Jiaqiang Zhong +7 more | Photonics

In visible light communication (VLC) systems, lenses are typically used to collimate light at the transmitter. However, due to the wide light emission angle of mini-LEDs, capturing light at large … In visible light communication (VLC) systems, lenses are typically used to collimate light at the transmitter. However, due to the wide light emission angle of mini-LEDs, capturing light at large angles using a lens at the transmitter can be challenging. This paper presents a design of a reflective cup at the mini-LED-based VLC transmitter. The redesigned reflective cup can collect most of the light and collimate it, achieving an efficiency of approximately 86% at a distance of 10 m in the simulation. In the experiment, error-free communication was achieved at a distance of 100 m with a data rate of 190 Mbps. To the best of our knowledge, a long-distance VLC system based on mini-LEDs is investigated for the first time. The reflective cup offers advantages, including high efficiency, low cost, and a simple structure. It holds reference value for addressing the issue of limited communication distance in underwater wireless optical communication (UWOC).

Hybrid Deep Learning-Based Optimization for Efficient 6G Free-Space Optical Communication

2025-06-20

Kuppani Sathish , S. M. Annapurna , Vamsi Krishna Reddy Bandaru +1 more | Research Square (Research Square)

<title>Abstract</title> With the introduction of 6G wireless communication, it is necessary to provide ultra-high reliability, high capacity and super-low latency. Free-Space Optical (FSO) solutions are main contributors to this. The … <title>Abstract</title> With the introduction of 6G wireless communication, it is necessary to provide ultra-high reliability, high capacity and super-low latency. Free-Space Optical (FSO) solutions are main contributors to this. The changing weather conditions in the air decrease the performance of light signals sent by FSO. We recommend a new system that merges Social Spider Optimisation and Waterwheel Plant Optimisation to ensure that the U-net architecture provides robust signal detection under turbulent conditions in FSO channels. Instead of conventional or mixed designs, ours matches network frameworks to optical channel perturbations, allowing the network to resist changes in environmental conditions. Results from multiple simulation tests show that BER, latency, spectral efficiency and capacity all improve considerably, reaching 25 bps/Hz, 1 ms and 10⁶ linked users. This method supports the IEEE 6G viewpoint and prepares the way for dependable, broadly applied FSO systems for defense, surveillance and remote sensing.

Enhanced Secure Encryption Scheme Using Dual Chaotic Models for OFDM-VLC System with HD-MMIM

2025-06-20

Zhixin Qi , Jie Ma , Lu Jia +3 more | Optics Express

Improved PAPR performance of the pre-coded optical OFDM in tricolor RGB based white LED for visible light communications

2025-06-19

Alak Halder , Ipsita Sengupta , Abhirup Das Barman | Journal of Optics

Mobile wireless light communication network

2025-06-19

Ziqian Qi , Linning Wang , Yingze Liang +4 more | Science China Information Sciences

Analysis of Outage Probability and Average Bit Error Rate of Parallel-UAV-Based Free-Space Optical Communications

2025-06-18

Sheng‐Hong Lin , Jin‐Yuan Wang , Xiao Hua | Entropy

Recently, free-space optical (FSO) communication systems utilizing unmanned aerial vehicle (UAV) relays have garnered significant attention. Integrating UAV relays into FSO communication and employing cooperative diversity techniques not only fulfill … Recently, free-space optical (FSO) communication systems utilizing unmanned aerial vehicle (UAV) relays have garnered significant attention. Integrating UAV relays into FSO communication and employing cooperative diversity techniques not only fulfill the need for long-distance transmission but also enable flexible adjustments of relay positions based on the actual environment. This paper investigates the performance of a parallel-UAV-relay-based FSO communication system. In the considered system, the channel fadings include atmospheric loss, atmospheric turbulence, pointing errors, and angle-of-arrival fluctuation. Using the established channel model, we derive a tractable expression for the probability density function of the total channel gain. Then, we derive closed-form expressions of the system outage probability (OP) and average bit error rate (ABER). Moreover, we also derive the asymptotic OP and ABER for a high-optical-intensity regime. Our numerical results validate the accuracy of the derived theoretical expressions. Additionally, the effects of the number of relay nodes, the field of view, the direction deviation, the signal-to-noise ratio threshold, the atmospheric turbulence intensity, the transmit power, and the transmission distance on the system's performance are also discussed.

Hybrid FSO/RF satellite-air-ground integration network for reliable ITS communication in desert environments

2025-06-18

Maadoud Djihane , Abdelkrim Hamza , M. Becherif | Optics Communications

Variable step size decision feedback equalizer-cascaded multi-modulus algorithm blind equalization technology based on avalanche photodiode gain control for multi-level pulse amplitude modulation modulated atmospheric laser communication

2025-06-17

Chang Shu , Xin Zhao , Xiaoying Ding +1 more | Optical Engineering

Achieving Ultra‐Brightness Green Light Source with Electro‐optical Conversion Efficiency up to 26.3% for Underwater Wireless Optical Communication

2025-06-17

Yuqin Guo , Guoqiang Wang , Lin Qiu +3 more | Advanced Functional Materials

Abstract Using blue lasers to excite green‐emitting phosphors offers a compelling solution to address the “green gap” issue, providing a high‐brightness green light source for underwater wireless optical communication (UWOC). … Abstract Using blue lasers to excite green‐emitting phosphors offers a compelling solution to address the “green gap” issue, providing a high‐brightness green light source for underwater wireless optical communication (UWOC). However, current green‐emitting phosphors show poor light conversion efficiencies or inadequate luminance saturation thresholds, impeding the development of brighter green light sources. Herein, the porous Lu 3 Al 5 O 12 :Ce phosphor ceramics are designed, which shows no change in quantum efficiency (82%) even after 6000 h of extended aging. This design results in a substantial improvement in light conversion efficiency (61.6%), luminous efficacy (286 lm·W⁻¹), and an exceptional luminance saturation threshold of 33 W·mm⁻ 2 , culminating in a maximum green light flux of 4720 lm. Moreover, the high‐directionality green light source device has been fabricated that achieves an illuminance of 6081 lx at a distance of 10 meters (15.0 W blue laser irradiation) with the electro‐optical conversion efficiency up to 26.3%, much higher than that using green laser directly (usually <20%). This setup enables long‐range underwater transmission of 65.3 meters with a peak data rate of 3.45 MHz, opening up new avenues for innovative advancements in UWOC technology.

Effect of atmospheric turbulence anisoplanatism toward LEO satellite-to-ground laser communications link

2025-06-16

Qingfang Jiang , Kanglian Zhao , Zhi Yong Liu +5 more | Optics Express

Beaconless Adaptive Optics for Atmospheric Laser Propagation with Multi-Plane Convolutional Neural Network

2025-06-16

Gregory DiComo , G. Witt , Joshua Isaacs +1 more | Optics Express

Probabilistic Modeling of Dust-Induced FSO Attenuation for 5G/6G Backhaul in Arid Regions

2025-06-16

Maged Abdullah Esmail | Applied Sciences

Free-Space Optical (FSO) communication systems operating in arid regions, especially those envisioned for current and future 5G/6G networks, are significantly affected by dust storms, which cause signal attenuation and service … Free-Space Optical (FSO) communication systems operating in arid regions, especially those envisioned for current and future 5G/6G networks, are significantly affected by dust storms, which cause signal attenuation and service disruptions. While previous studies have proposed deterministic models to characterize attenuation in both controlled and real environments, probabilistic modeling approaches remain largely unexplored, particularly for capturing the variability of FSO signal attenuation under dust conditions. This study proposes a probabilistic model for FSO signal attenuation developed from experiments conducted in a repeatable and well-characterized controlled dust chamber. The chamber-based setup allowed precise manipulation of dust visibility levels and consistent data collection, serving as a benchmark for statistical modeling. We analyzed the measurements to fit appropriate probability distributions for modeling the signal attenuation as a random variable. The empirical data were fitted to several candidate distributions, and the Johnson SB distribution consistently achieved superior performance with R2≥0.95 and RMSE and MAE values close to zero across all dust conditions. The results offer a foundational framework for modeling dust-induced attenuation as a random process, providing statistical bounds for FSO link planning in desert environments.

SDR implementation of a DSSS detector based Light CNN for cognitive radio.

2025-06-16

Okba Nesraoui , Djamal Teguig , Saïd Sadoudi | Physica Scripta

Abstract Direct Sequence Spread Spectrum (DSSS) communication has gained&#xD;significant traction in both civil and military communications and applications, owing&#xD;to its high processing gain, anti-jamming capability, and low probability of interception.&#xD;Due … Abstract Direct Sequence Spread Spectrum (DSSS) communication has gained&#xD;significant traction in both civil and military communications and applications, owing&#xD;to its high processing gain, anti-jamming capability, and low probability of interception.&#xD;Due to the wide bandwidth utilized in transmission, the power spectral density of a&#xD;DSSS signal may drop below the noise level. Consequently, detecting such a signal&#xD;poses challenges in cognitive radio networks. In this paper, the detection of DSSS&#xD;signals in a blind scenario without any preprocessing of the received signals is conducted&#xD;using a proposed deep learning model. This model, named DET-CNN, is built upon a&#xD;Convolutional Neural Network (CNN).&#xD;Through simulations and experimental analysis, the detection performance of&#xD;DET-CNN in various scenarios has been assessed and evaluated, contrasting it with&#xD;traditional methods such as : energy detection, autocorrelation detection methods,&#xD;goodness of fit and models from the literature across different Signal-to-Noise Ratios&#xD;(SNRs) in various channels. The results indicate that the detection performance of&#xD;the proposed model surpasses the existing methods, whether based on conventional&#xD;techniques or deep learning models. Our model achieved a detection probability of&#xD;100% at SNRs of -12 dB and -10 dB with synthetic and real data, respectively.

Atmospheric turbulence mitigation in adaptive MIMO hybrid RF/FSO links using MPPM/M-QAM modulation and TAS-MRC diversity under pointing errors

2025-06-14

Ebrahim E. Elsayed , Mohamed Yakout , Ahmed S. Samra | Journal of Optical Communications

Abstract Ground-based Free-Space Optical (FSO) communication networks are gaining prominence due to their high data rates, bandwidth efficiency (BE), cost-effectiveness, and security. However, their performance is hindered by atmospheric turbulence, … Abstract Ground-based Free-Space Optical (FSO) communication networks are gaining prominence due to their high data rates, bandwidth efficiency (BE), cost-effectiveness, and security. However, their performance is hindered by atmospheric turbulence, weather conditions, and pointing errors. This work proposes a hybrid Multiple-Input Multiple-Output (MIMO) Radio Frequency (RF)/FSO system with adaptive modulation to address these challenges. We analyze M-ary Pulse Position Modulation (MPPM) over Gamma–Gamma fading channels under varying turbulence levels and pointing errors, employing equal gain combining diversity to improve robustness. Closed-form expressions for the average bit error rate and outage probability are derived using the Meijer G-function. Furthermore, a novel hybrid MPPM/M-Quadrature Amplitude Modulation scheme is introduced to enhance BE and link reliability. The proposed system is compared with conventional methods, demonstrating superior performance via Monte Carlo simulations. Additionally, a MIMO hybrid RF/FSO system using transmit aperture selection and maximal ratio combining is analyzed to mitigate fading effects. Derived expressions for the average symbol error probability validate the gains of the hybrid modulation approach. The adaptive transmission modulation scheme significantly improves BE over nonadaptive techniques, leveraging the complementary strengths of RF and FSO channels.

Channel-aware outage modeling for dual-hop mixed optical wireless communication systems

2025-06-14

Anshul Vats , Meenakshi Gupta , Shilpi Pal +3 more | Journal of Optical Communications

Abstract This paper presents an in-depth analysis of the outage performance in a dual-hop mixed communication system that combines Free Space Optical (FSO) and Underwater Optical Communication (UWOC) links. The … Abstract This paper presents an in-depth analysis of the outage performance in a dual-hop mixed communication system that combines Free Space Optical (FSO) and Underwater Optical Communication (UWOC) links. The closed-form expressions of the outage probability of the system are derived, while considering practical channel conditions. Specifically, the FSO hop is modeled using Gamma–Gamma statistics to account for pointing errors and atmospheric turbulence, while the UWOC channel follows an Exponential Generalized Gamma (EGG) fading distribution to capture underwater impairments. To validate the analytical results, extensive numerical simulations are conducted, highlighting the impact of key parameters – such as path loss, scintillation, angle-of-arrival variations, water salinity, and pointing instability – on the performance of the considered system.

Visible Light Communication Technologies: A Review of IEEE 802.15.7 and Its Role in Next‐Generation Networks

2025-06-13

Monica Bhutani , Bharat Singh , Ashutosh Gupta +5 more | International Journal of Communication Systems

ABSTRACT Visible light communication (VLC) is a relatively new wireless communication technology that uses visible light to provide high‐speed, secure, and interference‐free data transfer. The current paper aims to review … ABSTRACT Visible light communication (VLC) is a relatively new wireless communication technology that uses visible light to provide high‐speed, secure, and interference‐free data transfer. The current paper aims to review the IEEE 802.15.7 standard in depth, focusing on how it will enhance VLC for future global networks. The main contributions are a detailed treatment of modulation schemes, namely, on–off keying (OOK), orthogonal frequency division multiplexing (OFDM), and pulse amplitude modulation (PAM) and a comparison of IEEE 802.15.7 with other VLC standards emphasizing its features. Finally, regarding use cases, the paper covers indoor positioning, extensive bandwidth data transfer, Internet of Things (IoT) compatibility, augmented reality, and virtual reality. It explores issues such as scalability, the issue of interference from ambient light, and the integration of the radio frequency (RF) system. Our validations and quantitative comparisons support the facts, and there is also a roadmap for future VLC research for implementation. This study presents possible opportunities and challenges for IEEE 802.15.7 to promote innovative growth for effective and sustainable communication systems among researchers and practitioners.

Characteristics of atmospheric optical turbulence in the free atmosphere over China derived from radiosonde data using the Thorpe method

2025-06-13

Xiaonan Hu , Xiaoqing Wu , Yinbo Huang +1 more | Optics Express

A performance study of an inter-UAV-based free space optical (FSO) system in the maritime environment

2025-06-12

Vijaya Ratnam Nallagonda , N.Shiva Nagaraju , Dantuluri Bhavani +3 more | Journal of Optical Communications

Abstract Recent advances in optical communication technology have enabled users to access high-data services on maritime links using the unmanned aerial vehicles (UAVs)-based free space optical (FSO) system. However, ensuring … Abstract Recent advances in optical communication technology have enabled users to access high-data services on maritime links using the unmanned aerial vehicles (UAVs)-based free space optical (FSO) system. However, ensuring reliable data communication for maritime links is a significant challenge due to harsh weather conditions. To address the growing demand for maritime links, we have proposed a maritime UAV-based FSO communication system that can support high-speed data rates and provide extended communication coverage. This paper investigates various aspects of maritime UAV-based FSO systems, including the basic architecture, different channel characteristics, and application scenarios. The paper also includes an analysis of the outage probability of the Inter UAV-based FSO communication system, considering the lognormal distributed channel model for the maritime Inter UAV-based FSO link with heterodyne detection (hd). Additionally, it presents an accurate analytical channel model between UAVs. It compares analytical and simulation results, considering maritime turbulence, pointing error, and hovering UAV fluctuations.

Channel capacity enhancement of RIS-assisted FSO communication system for high-speed trains access connectivity

2025-06-11

Abhishek Kumar , Kehariom Dewangan , Prabu Krishnan | Physical Communication

Spectrally efficient DCO-GFDM modulation using discrete cosine transform for indoor VLC systems

2025-06-06

Haidar Zaeer Dhaam , Faris Mohammed Ali | Journal of Optics

Avalanche Photodiode-Based Deep Space Optical Uplink Communication in the Presence of Channel Impairments

2025-06-03

Wenjng Guo , Xiaowei Wu , Lei Yang | Photonics

Optical communication is a critical technology for future deep space exploration, offering substantial advantages in transmission capacity and spectrum utilization. This paper establishes a comprehensive theoretical framework for avalanche photodiode … Optical communication is a critical technology for future deep space exploration, offering substantial advantages in transmission capacity and spectrum utilization. This paper establishes a comprehensive theoretical framework for avalanche photodiode (APD)-based deep space optical uplink communication under combined channel impairments, including atmospheric and coronal turbulence induced beam scintillation, pointing errors, angle-of-arrival (AOA) fluctuations, link attenuation, and background noise. A closed-form analytical channel model unifying these effects is derived and validated through Monte Carlo simulations. Webb and Gaussian approximations are employed to characterize APD output statistics, with theoretical symbol error rate (SER) expressions for pulse position modulation (PPM) derived under diverse impairment scenarios. Numerical results demonstrate that the Webb model achieves higher accuracy by capturing APD gain dynamics, while the Gaussian approximation remains viable when APD gain exceeds a channel fading-dependent gain threshold. Key system parameters such as APD gain and field-of-view (FOV) angle are analyzed. The optimal APD gain significantly influences the achievement of optimal SER performance, and angle of FOV design balances AOA fluctuations tolerance against noise suppression. These findings enable hardware optimization under size, weight, power, and cost (SWaP-C) constraints without compromising performance. Our work provides critical guidelines for designing robust APD-based deep space optical uplink communication systems.