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

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

Summary: Multi‐user optical code division multiplexing (OCDMA) in visible light communication (VLC) is an imminent domain for providing an even distribution of available bandwidth and improved security. Q4R1Zero cross‐correlation (ZCC) codes are widely reported, and improved performance is offered by them due to insignificant multiple access interference (MAI). However, practically, MAI exists in ZCC codes due to adjacent weights (W) in the code matrix rows for each user. Therefore, a novel ZCC code with a nonadjacent W is designed in this work to eradicate MAI limitations and is named weight managed ZCC codes (WMZCC). An indoor 100 Gbps/User OCDMA‐VLC system is realised using polarisation division multiplexed quadrature phase shift keying (PDM‐QPSK) and digital signal processing (DSP). Incorporation of DSP in the coherent receiver compensates the effects of dispersion and nonlinear effects and also performs phase estimation. Further, a state‐of‐the‐art comparison of WMZCC codes with diagonal identity matrix (DIM) and zero cross‐correlation resultant weight (ZCCRW) codes has been performed in terms of log symbol error rate (SER), Q factor, error vector magnitude percentage (EVM%) and log bit error rate (BER) log at different VLC lengths, Q4R1Transmitter half angles (THA), incidence half angles (IHA) and optical concentrators (cm2). Constellations are analysed with and without DSP, and according to the author's best knowledge, a 100 Gbps VLC system for five users covering 6 m at −3.42 log BER is demonstrated for the first time. Results revealed that weight management in WMZCC codes makes its performance improve as compared with ZCCRW and DIM codes. [ABSTRACT FROM AUTHOR]

Summary: Visible light communication (VLC) is considered to be a great replacement or complement to existing radio frequency networks to provide the future fifth‐generation (5G) wireless technology with higher data rates for indoor connectivity, which alleviates the traffic demand. Therefore, many issues emerged regarding the security in 5G networks as human safety is at risk. This work presents a comprehensive study on the physical‐layer security (PLS) and solutions in 5G networks, specifically, the security of VLC technology as one of the core PLS solutions for 5G future wireless networks. Furthermore, VLC threats and PLS solutions are extensively investigated. Based on our study, we propose a new indoor VLC secure model to enhance the secrecy performance in VLC networks using a combination of multiple PLS techniques to achieve this aim as beamforming, secure communication zones, and friendly jamming. The simulation results with respect to the received optical power and signal‐to‐noise ratio (SNR) prove that the proposed indoor VLC model can improve the secrecy performance. As the user's SNR exceeded 100 dB and optical received power reached 15 mW, the malicious user's SNR barely reached 30 dB with a 4‐μW received power outside the target zone increasing his interference level. Finally, future research directions in VLC security are outlined to encourage future research. [ABSTRACT FROM AUTHOR]

This article reviews a few modulations commonly used in visible light communication with their recent development, explain why applying micro‐LED will benefit the speed, accuracy, secrecy, and how it will expand the application scenarios of visible light communication. [ABSTRACT FROM AUTHOR]

This article reviews a few modulations commonly used in visible light communication with their recent development, explain why applying micro‐LED will benefit the speed, accuracy, secrecy, and how it will expand the application scenarios of visible light communication. [ABSTRACT FROM AUTHOR]

This study investigates cooperative inter‐lighting interference cancellation (C‐ILIC) in indoor multiple‐input single‐output (MISO) visible light communication (VLC) to overcome co‐channel interference (CCI) and provide connectivity, even if there is link blockage. C‐ILIC exhibits great improvement in the average bit error rate (BER) performance and the transmission capacity. VLC plays an important role in handling the increasing data traffic in indoor environments. When the transmitters simultaneously send unique data over the same frequency resources, and the receiver obtains the different signals, CCI occurs because the signals interfere with each other. C‐ILIC employs cooperative transmission to forward a composite data, which consists of the high received power data and the low received power data, and ILIC to decode the high received power data and reduce CCI in the low received power data before decoding. Through computer simulations, the BER performance of C‐ILIC overcomes the conventional ILIC in any position because the receiver power ratio always complies with the threshold. Despite the BER performance deteriorating in the presence of link blockage, the data connection is guaranteed when the obstruction is not severe. Therefore, C‐ILIC can provide reliable communication and full connectivity within a room. [ABSTRACT FROM AUTHOR]

Summary: With the development of new generation lighting sources, visible light communication (VLC) system has become a complementary solution to traditional radio frequency wireless system. However, the error performance of VLC system is degraded because of multipath effects and interference from other lighting sources that, in turn, reduce the communication range. This work targets the issue of performance degradation of VLC systems in terms of communication range and demonstrates a VLC system design that utilizes forward error correction (FEC) codes as the main tool to fix this issue. Furthermore, the work also covers practical implementation of the proposed VLC system using UART modules programmed in MATLAB. The hardware results demonstrate that the communication range of the proposed VLC system is enhanced up to 0.5 m. Over and above, it is also shown through simulations that the coding gain of the proposed design is more when compared with existing VLC system(s). [ABSTRACT FROM AUTHOR]

In this study, the authors propose an enhanced inter‐lighting interference cancellation (E‐ILIC) in order to distinguish the received signals, combating the equal powers at the receiver side and hence improve the average bit error rate (BER) performance of a multiple‐input‐single‐output visible light communication (VLC) system. VLC is a promising technology for indoor environments, it makes use of the light emitting diode (LED) lamps already installed to transmit information through the visible light. When several LEDs transmit simultaneously different data to increase the transmission capacity, it leads to co‐channel interference that degrades the BER performance. For this reason, they investigate E‐ILIC that is a combination of ILIC with closed loop power control to receive the signals with different power level. It employs power allocation at the transmitter when the received power ratio does not comply with a specific threshold. Furthermore, it reduces significantly the interference between adjacent LED lamps, obtaining useful information at the receiver side. Through computer simulations, E‐ILIC achieves the best average BER performance in any user position when the assignment of the power weights is correctly performed on the LEDs. [ABSTRACT FROM AUTHOR]

Abstract: Visible light communication has gained widespread attention in recent times and is expected to complement existing network infrastructure such as wireless local area networks, cellular networks as well as power line communications to provide high speed connectivity. The intensity of the received light depends on the intensity and wavelength of the transmitter, wavelength sensitivity range of the receiver, and also on the ambient light. Depending on the intensity of the received light, a photo‐sensor has to detect and decode the received data, with minimum probability of error. For binary transmission, this is achieved by choosing a decision threshold. In this paper, a threshold detection mechanism is presented by fitting parametric probability distributions to the sensed signal levels. It is shown that the threshold value obtained using this method yields error probability close to zero. [ABSTRACT FROM AUTHOR]

We experimentally demonstrate the LED-based visible light transmission (VLC) over a 100-m special designed low-loss ultra-large effective area (diameter >1 mm) pure silica fiber (ULEAPS fiber). Three-channel wavelength multiplexing is achieved by using a single chip RGB LED as the light source. The total insertion loss after 100-meter transmission for the red light, green light and blue light are 1.015, 1.582, and 3.660 dB, respectively. A total data rate of 3.1 Gb s−1 is experimentally achieved over 5-m ULEAPS fiber and a data rate of 2 Gb s−1 is achieved over 100-m fiber with the bit error rate (BER) below 7% forward error correction (FEC) limit of 3.8 × 10−3. The results obtained here may also serve as a valuable information on how to realize LED based VLC transparent transmission from free-space to a pure silica fiber utilizing a commercial illumination LED as the light source. [ABSTRACT FROM AUTHOR]

The Paris agreement at the 21st Conference of the Parties (COP21) emphasizes the reduction of greenhouse gas emissions and increase in energy consumption in all areas. Thus, an important aspect is energy saving in buildings where the lighting is a major component of the electrical energy consumption. This paper proposes a building energy management system employing visible light communication (VLC) based on LED lighting. The proposed management system has key characteristics including personalization and localization by utilizing such VLC advantages as secure communication through light and location-information transmission. Considering the efficient implementation of an energy-consumption adjustment using LED luminaires, this paper adopts variable pulse position modulation (VPPM) as a VLC modulation scheme with simple controllability of the dimming level that is capable of providing a full dimming range. This paper analyzes the VPPM performances according to variable dimming for several schemes, and proposes a VPPM demodulation architecture based on dimming-factor acquisition, which can obtain an improved performance compared to a 2PPM-based scheme. In addition, the effect of a dimming-factor acquisition error is analyzed, and a frame format for minimizing this error effect is proposed. [ABSTRACT FROM AUTHOR]

Recently, orthogonal frequency-division multiplexing (OFDM) was applied to VLC systems owing to its high rate capability. On the other hand, a real-valued unipolar OFDM signal for VLC significantly reduces bandwidth efficiency. For practical implementation, channel estimation is required for data demodulation, which causes a further decrease in spectral efficiency. In addition, the large fluctuation of an OFDM signal results in poor illumination quality, such as chromaticity changes. This paper proposes a spectrally efficient method based on a hidden-pilot-aided precoding technology for VLC with less flickering than a conventional OFDM-based method. This approach can obtain channel information without any loss of bandwidth efficiency while ensuring illumination quality by reducing the flickering effect of an OFDM-based VLC. The simulation results show that the proposed method provides a 6.4% gain in bandwidth efficiency with a 4% reduction in flicker compared to a conventional OFDM-based method. [ABSTRACT FROM AUTHOR]

In this paper, a new architecture is proposed to achieve complexity efficiency in implementing variable pulse position modulation (VPPM). VPPM, specified in IEEE 802.15.7, can support wireless communication and dimming control simultaneously using visible light. The proposed architecture is based on the VPPM signal property in which the transition point of the modulated output is obtained by counting the sample index and comparing it to both the assigned dimming factor and the transmitting data. Therefore, the proposed architecture can be composed of simple logics, including a counter, a comparator, and an inverter, all of which are insensitive to the dimming resolution in contrast to a conventional codeword-table method. This paper describes the verification of the proposed algorithm through a register-transfer level implementation of the codeword and proposed architectures. In comparison with the codeword-table method, the proposed method gains a nine-fold complexity reduction at a 1% dimming-step resolution. [ABSTRACT FROM AUTHOR]

ABSTRACT Visible light communication (VLC) has many issues, including realizing complex modulations, increasing data rate, addressing the light emitting diode (LED) bandwidth limitation, and achieving multiservice capabilities such as for location-based service (LBS). Therefore, we investigated frequency optimization for VLC parameters such as offset OFDM frequency location, allocated RF signal frequency location, allocated RF signal input power, operating point, and clipping. We experimentally demonstrated the characteristics of the proposed system. The results show that received offset frequency division multiplexing (OFDM) can achieve a 12-Mbps data rate with a BER of 8 × 10−4. Additionally, the received allocated RF signal can satisfy a BER requirement of 10−4 after conversion from its EVM. The transmission distance was 1.8 m in an indoor environment when using white LED. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1431-1437, 2014 [ABSTRACT FROM AUTHOR]

ABSTRACT This paper theoretically studies the performance of transmission control protocol (TCP) over visible light communications (VLC) networks when the automatic-repeat request, selective repeat (ARQ-SR) protocol is employed in the link layer. We analytically derive TCP throughput considering the impact of ARQ-SR parameters and different VLC physical factors, including inter-symbol interference (ISI), signal reflection and light power distribution. Numerical results show that TCP throughput is strongly dependent on the location of VLC user due to impacts of ISI and signal reflection. It is also seen that the use of ARQ-SR could significantly improve both the maximum value and the distribution of TCP throughput in the VLC network. Especially, with a proper selection of the number of re-transmissions by the ARQ-SR protocol, the dependence of TCP throughput on user location caused by ISI, light signal reflection and distribution could be effectively remedied. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

We propose a visible light communication system in which the color and brightness are controllable. Pulse width modulation and variable pulse position modulation (VPPM) schemes are used to control the color and brightness, respectively. A digital algorithm to decode VPPM signals is suggested and implemented. A seamless transmission is observed in a testbed experiment under various environmental conditions. The proposed scheme can be applied to emotionallighting- based wireless optical communication. [ABSTRACT FROM AUTHOR]

In this article, we propose an indoor location estimation algorithm that uses the signal extinction ratio distribution of LED-based visible light communication.To improve the positioning accuracy, we use the received extinction ratio from different LED transmitters. In order to mitigate interference between transmitters, a location code was sent using time division multiplexing (TDM). We verified the feasibility of the proposed position estimation algorithm with an experimental demonstration. The proposed algorithm provided positioning accuracy with a 1.5787-cm mean distance error for a given equilateral triangle cell with three 60-cm sides. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1385-1389, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27575 [ABSTRACT FROM AUTHOR]

The impact of receiver's tilted angle on the channel capacity in visible light communications (VLCs) is investigated. First, the system model is analysed. On the basis of the system model, the lower and upper bounds on the channel capacity for the VLC are presented. An optimisation problem is formulated to improve the channel capacity by tilting the receiver plane. The proposed problem is shown to be a convex optimisation problem, which is efficiently solved by using the CVX toolbox for MATLAB. Numerical results show that the channel capacity can be dramatically improved by tilting the receiver plane properly. [ABSTRACT FROM AUTHOR]

In visible light communication (VLC), on–off keying (OOK) is able to achieve the best BER performance as compared with variable pulse position modulation. However, OOK has a significant defect that the dimming levels (i.e. brightness) of illumination are greatly affected by the input ratio of 0 and 1 bits. To overcome this drawback, OOK with run length limited (RLL) line codes such as Manchester code or 8B10B block code has been studied in IEEE 802.15.7 VLC standard. However, those mechanisms cannot support the dimming levels more than 50%. Also, spectral efficiency of those mechanisms is reduced and then it is causative of BER performance degradation. An effective RLL line coding scheme is proposed in order to enhance the brightness and BER performance as compared with conventional RLL coding schemes. The simulation results demonstrate that the proposed coding scheme is superior to Manchester code and 8B10B block code in terms of the brightness and BER performance. [ABSTRACT FROM AUTHOR]

Light‐emitting diode (LED) access point (AP) scheduling can provide both significant performance gains and flexible user access for visible light communications. However, the scheduling for multiple moving users, which requires adaptive LED AP scheduling for user movements and is practical in common scenarios, has so far rarely been studied. An incremental scheduling scheme is proposed to introduce a time division scheduling framework to solve the scheduling problem with multiple moving users. The proposed scheme consists of two phases: global scheduling and local scheduling. In the global scheduling phase, a scheduling scheme based on graph theory is proposed to assign users to different timeslots to eliminate inter‐user interference. In the local scheduling phase, the result of global scheduling is adjusted for user movements. Simulation results show that the proposed scheme improves system capacity with reduced complexity. [ABSTRACT FROM AUTHOR]