Visible Light Communication System

Visible light communication (VLC) systems have become promising candidates to complement conventional radio frequency (RF) systems due to the increasingly saturated RF band and the potentially high data rates that can be achieved by VLC systems. Over the last decade, significant research effort has been directed towards the development of VLC systems due to their numerous advantages over RF systems, such as the availability of simple transmitters (light emitting diodes, LEDs) and receivers (silicon photo detectors), better security at the physical layer, improved energy efficiency due to the dual functionally (i.e., illumination and communication) and hundreds of THz of license-free bandwidth. However, there are several challenges facing VLC systems to achieve high data rates (multi gigabits per second). These challenges include the low modulation bandwidth of the LEDs, co-channel interference (CCI), inter symbol interference (ISI) due to multipath propagation and the light unit (i.e., VLC transmitter) should be ‘‘ON’’ all the time to ensure continuous communication. This thesis investigates a number of techniques to overcome these challenges to design a robust high-speed indoor VLC system with full mobility. A RGB laser diode (LD) is proposed for communication as well as illumination. The main goal of using LD is to enable the VLC system to achieve multi-gigabits data rates when employing a simple modulation technique (such as on-off keying (OOK)), thus adding simplicity to the VLC system. A delay adaptation technique (DAT) is proposed to reduce the delay spread and enable the system to operate at higher data rates (10 Gb/s in our case). The thesis proposes employing angle diversity receivers (ADR) and imaging diversity receivers to mitigate the impact of ISI, CCI, reduce the delay spread (increase the channel bandwidth) and increase the signal to noise ratio (SNR) when the VLC system operates at high data rates (5 Gb/s and 10 Gb/s) under the effects of mobility and multipath dispersion. Moreover, the work introduces and designs three new VLC systems, an ADR relay assisted LD-VLC (ADRR-LD), an imaging relay assisted LD-VLC (IMGR-LD) and a select-the-best imaging relay assisted LD-VLC (SBIMGR-LD), which are modelled and their performance is compared at 10 Gb/s in two VLC room sizes (5m × 5m × 3m and 4m × 8m × 3m). As well as modelling in two different room scenarios: an empty room and a realistic environment were considered. The work also introduces and designs a high-speed fully adaptive VLC system that employs beam steering and computer generated holograms (CGHs), which has the ability to achieve 20 Gb/s with full receiver mobility in a realistic indoor environment. Furthermore, a new high-speed fast adaptive VLC system based on a divide-and-conquer methodology is proposed and integrated with the system to reduce the time required to identify the optimum hologram. The new system has the ability to achieve 25 Gb/s in the worst case scenario. This thesis also proposes four new infrared (IR) systems to support VLC systems when the light is totally turned off. In addition, it introduces the concept of a collaborative VLC/IR optical wireless (OW) system and investigates the impact of partial dimming on the VLC system performance. An adaptive rate technique (ART) is proposed to mitigate the impact of light dimming. Finally, an IROW system (cluster distributed with beam steering) is introduced to collaborate with a VLC system to maintain the target data rate in the case of partial dimming

Simulation model of energy fluxes in passive solar greenhouses with a concrete north-wall

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Simulation model of energy fluxes in passive solar greenhouses with a concrete north-wall

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Holograms in Optical Wireless Communications

Adaptive beam steering in optical wireless communication (OWC) system has been shown to offer performance enhancements over traditional OWC systems. However, an increase in the computational cost is incurred. In this chapter, we introduce a fast hologram selection technique to speed up the adaptation process. We propose a fast delay, angle and power adaptive holograms (FDAPA-Holograms) approach based on a divide and conquer methodology and evaluate it with angle diversity receivers in a mobile optical wireless (OW) system. The fast and efficient fully adaptive FDAPA-Holograms system can improve the receiver signal to noise ratio (SNR) and reduce the required time to estimate the position of the receiver. The adaptation techniques (angle, power and delay) offer a degree of freedom in the system design. The proposed system FDAPA-Holograms is able to achieve high data rate of 5 Gb/s with full mobility. Simulation results show that the proposed 5 Gb/s FDAPA-Holograms achieves around 13 dB SNR under mobility and under eye safety regulations. Furthermore, a fast divide and conquer search algorithm is introduced to find the optimum hologram as well as to reduce the computation time. The proposed system (FDAPA-Holograms) reduces the computation time required to find the best hologram location from 64 ms using conventional adaptive system to around 14 ms

Collaborative VLC/IROW Systems

Dimming is an important feature of an indoor lighting system where the illumination level can be controlled by the user. Therefore, integrating a visible light communication (VLC) system with an illumination system poses some challenges. One of the main issues is that the light unit should be “ON” all the time to ensure continuous communication. To ensure acceptance and adoption of VLC systems, an important issue should be addressed: how to communicate when the lights are “OFF” or partially dimmed. In this chapter, we propose five new infrared optical wireless (IROW) systems to support VLC systems when the light is totally turned off or significantly dimmed. To take advantage of both VLC and IROW, we introduce and implement the concept of a collaborative VLC/IROW system. In addition, we investigate the impact of partial dimming on the VLC system’s performance, and we propose an adaptive rate technique (ART) to mitigate the impact of light dimming. Moreover, in the case of no dimming, the VLC and IROW systems can collaborate to increase the data rate so it is higher than that in the pure VLC system. We have achieved 10 Gbps in an indoor environment, which is a 2× increase in the data rate compared with a pure VLC system

Design, analysis and construction of a simple pulse duplicator system

One of the most important human diseases that need to be considered in terms of development of the medical engineering devices is cardiovascular disease which is a significant cause of death globally recently. Valvular heart disease is normally treated by restoring or altering heart valves with an artificial one. But the new prosthetic valve designs necessitate testing for durability estimate and failure method. It is significant to simulate the circulation system by the building of a pulse duplicator system. This study is stated by clarifying the parameter and implementation steps of the pulse duplicator system in which the different researchers have utilized the system and tried to explain the design steps of using this system without going into the system design by steps or what are the main part of this system and how can be implemented, tested, and developed individually. In this design, a DC motor produces, through a hydraulic piston, a flow pulse to the left ventricle chamber model, which is linked with two interchangeable prosthetic heart valves. The computer is used to control and process data from volumetric flow rate and image. The findings show that the linear displacement, the velocity of the piston and the linear acceleration regularly become significant particularly and follows a sinusoidal wave shape during one cycle, when (crank length/connecting rod length) value is equal 0.2 or less. Several sets of measured flow rate readings were obtained by using flow meter sensor YF-S201, results after calibration showed the error rate falls within permissible limit

Uplink Design in VLC Systems with IR Sources and Beam Steering

The need for high-speed local area networks to meet the recent developments in multimedia and video transmission applications has recently focused interest on visible light communication (VLC) systems. Although VLC systems provide lighting and communications simultaneously from light emitting diodes, LEDs, the uplink channel design in such a system is a challenging task. In this paper, we propose a solution in which the uplink challenge in indoor VLC is resolved by the use of an Infrared (IR) link. We introduce a novel fast adaptive beam steering IR system (FABS-IR) to improve the uplink performance at high data rates while providing security for applications. The goal of our proposed system is to enhance the received optical power signal, speed up the adaptation process and mitigate the channel delay spread when the system operates at a high transmission rate. The channel delay spread is minimised from 0.22 ns given by hybrid diffuse IR link to almost 0.07 ns. At 2.5 Gb/s, our results show that the imaging FABS-IR system accomplished about 11.7 dB signal to noise ratio (SNR) in the presence of multipath dispersion, receiver noise and transmitter mobility