Performance Evaluation of Multi-gigabit Indoor Visible Light Communication System

This paper presents a performance evaluation of a mobile multi-gigabit visible light communication (VLC) system in two different environments. The VLC channel characteristics and links were evaluated under the diverse situations of an empty room and a room with very strong shadowing effects resulting from mini cubicle offices. RGB laser diodes (LDs) were used to mitigate the low modulation bandwidth of conventional transmitters (light emitting diodes, LEDs) in the VLC system. In addition, an angle diversity receiver (ADR) was introduced to mitigate intersymbol- interference (ISI). Furthermore, a delay adaptation technique was used to further reduce the effect of ISI and multipath dispersion. The combination of delay adaptation and ADR (DAT ADR system) added a degree of freedom to the link design, which resulted in a VLC system that has the ability to provide high data rates (i.e. 5 Gbps) in the considered harsh indoor environment. Our proposed system used a simple on-off keying (OOK) modulation format and it was able to provide data rates of 5 Gbps and a bit-error-rate (BER) of 10-3 in the worst case scenario in the considered realistic indoor environment

Mobile Multi-Gigabit Visible Light Communication System in Realistic Indoor Environment

The main challenges facing high data rate visible light communication (VLC) are the low-modulation bandwidth of the current transmitters (i.e., light emitting diodes), the intersymbol interference (ISI) caused by the multipath propagation and cochannel interference (CCI) due to multiple transmitters. In this paper, for the first time, to the best of our knowledge, we propose, design, and evaluate the use of laser diodes (LDs) for communication as well as illumination. In addition, we propose an imaging receiver for a mobile VLC system to mitigate ISI. A novel delay adaptation technique is proposed to mitigate CCI, maximize the signal to noise ratio, and reduce the impact of multipath dispersion under user mobility.The proposed imaging system is able to provide data rates of 5 Gb/s in the worst-case scenario.The combination of a delay adaptation approach with an imaging receiver (DAT imaging LD-VLC system) adds a degree of freedom to the link design, which results in a VLC system that has the ability to provide higher data rates (i.e., 10 Gb/s) in the considered harsh indoor environment.The proposed technique (delay adaptation) achieves significant improvements in the VLC channel bandwidth (more than 16 GHz) over an imaging system in the worst-case scenario.The VLC channel characteristics and links were evaluated under diverse situations including an empty room and a room with very strong shadowing effects resulting from minicubicle offices

High-Speed Indoor Visible Light Communication System Employing Laser Diodes and Angle Diversity Receivers

The two main challenges facing high data rate visible light communication (VLC) are the low modulation bandwidth of the current transmitters (i.e. light emitting diodes, LEDs) and the inter symbol interference (ISI) caused by multipath propagation. In this paper, we evaluate laser diodes (LDs) as a source of illumination and communication instead of LEDs for a VLC system in conjunction with an angle diversity receiver (ADR). The main advantage of using LDs is their high modulation bandwidth that enables communication at data rates of multi gigabits per second for VLC when using a suitable receiver, such as an ADR, which mitigates the ISI. Our proposed system uses simple on-off keying (OOK) modulation, and it is able to provide data rates of 5 Gbps and a bit-error-rate (BER) of 10-6 in the worst case scenario

Hybrid diffuse IR transmitter supporting VLC systems with imaging receivers

Indoor visible light communication (VLC), using white-LED lighting, generally assumes lights are ON during communications. In this paper, we propose a new Hybrid diffuse Infrared transmitter (HDIrT) coupled with an imaging receiver to support VLC system when the light is dimmed or is totally turned off. Infrared (IR) optical communications boasts similar advantages as VLC systems. It can also provide high transmission rates. The ultimate goal of our proposed system is to increase the signal to noise ratio (SNR), mitigate the channel delay spread and the effect of inter-symbol-interference (ISI) when the system operates at a high data transmission rate. The delay spread is reduced from 1.55 ns to about 0.1 ns when a narrow field-of-view (FOV) imaging receiver replaces a wide FOV non-imaging receiver. At a higher data rate of 2.5 Gb/s, the simulation results show that the imaging HDIrT system achieves about 17 dB SNR in the presence of multipath dispersion, receiver noise and mobility

25 Gbps Mobile Visible light Communication System Employing Fast Adaptation Techniques

Visible light communication (VLC) systems have typically operated at data rates below 20 Gbps and operation at this data rate was shown to be feasible by using laser diodes (LDs), beam steering, imaging receivers and delay adaptation techniques. However, an increase in the computational cost is incurred. In this paper, we introduce fast computer generated holograms (FCGHs) to speed up the adaptation process. The new, fast and efficient fully adaptive VLC system can improve the receiver signal to noise ratio (SNR) and reduce the required time to estimate the position of the VLC receiver. In addition, an imaging receiver and a delay adaptation technique are used to reduce the effect of inter symbol interference (ISI) and multipath dispersion. Significant enhancements in the SNR, with VLC channel bandwidths of more than 36 GHz are obtained resulting in a compact impulse response and a VLC system that is able to achieve higher data rates (25 Gbps) with full mobility in the considered indoor environment

Adaptive receiver for visible light communication system

The future of visible light communication (VLC) systems relies on achieving moderate to high data rates and the ability to design a low complexity system, as these will play a major role in the next generation communication networks. In this paper, we propose, design, and evaluate the use of an adaptive receiver to mitigate the inter-symbol interference (ISI) and improve the overall VLC system performance while using a single element wide field of view (FOV) photodetector. In addition, we optimise the adaptive receiver by employing a different number of buffers to find the optimum configurations in terms of reducing the complexity and achieving the best performance. The proposed adaptive receiver is able to provide data rates of 1 Gbps with a BER of 10¯⁵ for OOK modulation in the worst case scenario

20 Gbps Mobile Indoor Visible Light Communication System Employing Beam Steering and Computer Generated Holograms

Visible light communication (VLC) systems have typically operated at data rates below 10 Gbps and operation at this data rate was shown to be feasible by using laser diodes (LDs), imaging receivers and delay adaptation techniques (DAT imaging LDs-VLC). However, higher data rates, beyond 10 Gbps, are challenging due to the low signal to noise ratio (SNR) and inter symbol interference (ISI). In this paper, for the first time, to the best of our knowledge, we propose, design and evaluate a VLC system that employs beam steering (of part of the VLC beam) using adaptive finite vocabulary of holograms in conjunction with an imaging receiver and a delay adaptation technique to enhance SNR and to mitigate the impact of ISI at high data rates (20 Gbps). An algorithm was used to estimate the receiver location, so that part of the white light can be directed towards a desired target (receiver) using beam steering to improve SNR. Simulation results of our location estimation algorithm (LEA) indicated that the required time to estimate the position of the VLC receiver is typically within 224 ms in our system and environment. A finite vocabulary of stored holograms is introduced to reduce the computation time required by LEA to identify the best location to steer the beam to the receiver location. The beamsteering approach improved the SNR of the fully adaptive VLC system by 15 dB at high data rates (20 Gbps) over the DAT imaging LDs-VLC system in the worst case scenario. In addition, we examined our new proposed system in a very harsh environment with mobility. The results showed that our proposed VLC system has strong robustness against shadowing, signal blockage and mobility

Cognitive, emotional and behavioral experiences of second-generation millennial Muslim American women with gendered Islamophobia

This qualitative research study centers on the Gendered Islamophobic experiences of Second-Generation Millennial Muslim American Women (2GMMAW). The study leans on a phenomenological approach informed by a modified Doing Difference framework and U.S. Third World Feminism and Differential Consciousness to call attention to omni-relevant identities for 2GMMAW in daily life and navigating Islamophobic experiences. Nine semi-structured interview guides were completed that inquired about the domains of Gendered Islamophobia (Disciplinary, Structural, Hegemonic, and Interpersonal) and called attention to their cognitive, emotional, and behavioral processes during these experiences. In addition, this study aims to address gaps in the literature mental health process for 2GMMAW and their Islamophobic experiences. The main outcomes from this study include the Invisible Load of Gendered Islamophobia, the Merry Muslimah, and Implications for Religion in Social Work education, research, and practice

Artificial Neural Network for LiDAL Systems

In this paper, we introduce an intelligent light detection and localization (LiDAL) system that uses artificial neural networks (ANN). The LiDAL systems of interest are MIMO LiDAL and MISO IMG LiDAL systems. A trained ANN with the LiDAL system of interest is used to distinguish a human (target) from the background obstacles (furniture) in a realistic indoor environment. In the LiDAL systems, the received reflected signals in the time domain have different patterns corresponding to the number of targets and their locations in an indoor environment. The indoor environment with background obstacles (furniture) appears as a set of patterns in the time domain when the transmitted optical signals are reflected from objects in LiDAL systems. Hence, a trained neural network that has the ability to classify and recognize the received signal patterns can distinguish the targets from the background obstacles in a realistic environment, especially given the mobility of targets (humans) which distinguishes them from static obstacles (furniture). The LiDAL systems with ANN are evaluated in a realistic indoor environment through computer simulation

Parallel Data Transmission in Indoor Visible Light Communication Systems

This paper presents an indoor visible light communication (VLC) system in conjunction with an imaging receiver with parallel data transmission (spatial multiplexing) to reduce the effects of the inter-symbol interference (ISI). To distinguish between light units (transmitters) and to match the light units used to convey the data with the pixels of the imaging receiver, we propose the use of subcarrier multiplexing (SCM) tones. Each light unit transmission is multiplexed with a unique tone. At the receiver, a SCM tone decision system is utilized to measure the power level of each SCM tone and consequently associate each pixel with a light unit. In addition, the level of co-channel interference (CCI) between light units is estimated using the SCM tones. Our proposed system is examined in two indoor environments taking into account reflective components (first and second order reflections). The results show that this system has the potential to achieve an aggregate data rate of 8 Gb/s with a bit error rate of 10 –6 for each light unit, using simple on-off-keying (OOK)