In this study, the authors demonstrate that transmission rate in white phosphorescent light emitting diode (LED) transmitter communication-illumination system can be increased significantly by simultaneous transmission of an additional infrared (IR) channel. Unlike in typical colour multiplexing, the IR channel does not require a dedicated receiver filter as the channel crosstalk can be removed using digital signal processing. Both channels can operate in synchronous or asynchronous mode. The experimental results in this study demonstrate a significant increase in the data rate.

Commercial light-emitting diodes are a low-cost and energy-efficient solution for the implementation of optical wireless communication, known as visible light communication (VLC). This technology has a huge growing interest, being recently a research spotlight in the scientific community, especially due to the increasing popularity and rapid development of self-sustainable smart houses and the Internet of Things. As the VLC link is free space, big challenges arise in its implementation. To improve the VLC performance, this work proposes an enhanced system solution integrating an optical amplifier. In this context, organic–inorganic hybrids incorporating a blue-emitting conjugated polymer with high quantum yield (>50%) were synthesised and processed as planar waveguides. The waveguides were tested in a testbed scenario, showing a signal amplitude improvement of 2.5 dB, establishing the proposed approach as a promising cost-effective solution for optical amplification in VLCs.

A new low-cost energy-saving concept in the modern light-emitting diode (LED) illumination system is developed and implemented using an isolated single-ended primary inductance converter (SEPIC). The dimming scheme presented in this study is a single-step with negligible distortion in the AC mains current as compared to the traditional low-cost triode for alternating current (TRIAC) dimming system, which distorts the AC mains current wave-shape beyond sinusoidal nature due to the phase-cut techniques. This dimming concept is completely retrofitted, no additional arrangement is required to initiate the dimming as compared to a TRIAC dimmer or other controllers. The isolated SEPIC converter is modelled and analysed in detail using the state-space average technique. The stability of the designed converter and overall closed-loop control are verified using Bode-plot analysis. The full load converter efficiency is found around 93%, which is much higher than the conventional flyback topology-based LED driver. The concept presented in this study is tested with the help of a laboratory prototype with an LED load of 60 W.

The advancement in white light-emitting diodes (LEDs) technology makes it the most preferred highly efficient lighting solution. Not only LEDs consume less energy and reduce carbon emissions, but also their average life expectancy is above 10 years, i.e., 50,000 h. Achieving more than 75% of energy savings has encouraged the widespread use of LEDs for indoor and outdoor applications, as well. As a consequence of the huge investments in the LED-based lighting industry, another emerging technology has grown, which is visible light communications (VLC). For instance, LEDs can switch to various light intensity levels at an extremely fast rate, i.e., imperceivable by a human eye, which allows data to be modulated through light, enabling wireless communications [1]. Recent research discusses how LEDs can be used for communication, positioning, and sensing [2]. Adopting VLC enables the use of an ultrawide range of unregulated visible light, offering 10,000 times more bandwidth capacity than radio frequency (RF)-based technologies. Rates of over 10 Gbps have already been demonstrated using LEDs, and an enticing rate of 100 Gbps was reported using laser diodes [3]. This chapter discusses state-of-the-art VLC modulation techniques, potential indoor scenarios, and associated challenges. In the first section, advancements in modulation schemes that are compatible with illumination requirements are highlighted. Such schemes enable the simultaneous offering of multiple wireless services, including communication, sensing, and security, and will even promote more efficient VLC systems. Then, this chapter discusses the possibility of coexisting VLC with RF technologies, followed by recent advancements inVLC-based multiple-input and multiple-output (MIMO) techniques. Finally, the potential of applying deep learning (DL) algorithms to improve the performance of VLC systems is investigated.

In this Letter, a recorded single channel of 6.915-Gbit/s white-light visible light communication (VLC) system is reported and experimentally demonstrated. By optimising the bit-loading algorithm onto the direct-current optical OFDM signal and without using an optical blue filter, the high data rate can be achieved. After a free-space propagation distance of 1.5 m, the white-light beam diameter of 14 cm and illuminance of 795 lux are measured. The proposed white-light VLC system can provide both lighting and communication simultaneously with functional propagation distance.

This study presents a review of smart light-emitting diode (LED) lighting systems applied to smart buildings. The study is focused on drivers, protocols, technologies, communication networks and applications. An extended overview of the methodologies used for LED lighting control in smart buildings is addressed. The study also presents an integrated architecture able to achieve the necessary services and control methodologies for intelligent building energy management system for LED lightings systems in smart buildings.

This study analysed GaN nanophosphors based white light-emitting diodes (WLEDs) with ultraviolet (UV) excitation. Graphene quantum dots (GQDs) used as a charge transfer medium to enhance the performance in terms of luminous efficacy and colour quality. The improvement in colour rendering and colour temperature has been observed with the increase in injection current. The luminous efficacy of radiation also gets improved with injection current and maximises up to 255 lm/W at 260 mA along with 90 colour rendering index and 7100 K correlated colour temperature. Mapping of higher surface temperature for GQD-based devices shows a better thermal stability, indicating the good heat dissipation capability of GQDs because of excellent thermal conductivity. Therefore, proposed WLEDs were found more competent with improved thermal quenching of phosphors for rare-earth-free solid-state lighting as compared to the blue chip-excited yellow phosphors.

This study presents an extendable full-colour light emitting diode (LED) display based on field-programmable gate array implementation. The LED display panel system includes memory management, image format conversion, serial parallel interface (SPI) interface, local scan techniques, LED driver and pulse width modulation (PWM) data control. To reduce I/O ports, data transmission system uses SPI interface to send the PWM data to the LED panels. A novel local scan technique, which could use a lower frequency for data transmission and achieve higher frame rate for LED display, is proposed. Each display module contains local memories for data self-scanning to LED. The display continues even if there is no new data input. The advantages are that the display rate does not care about the speed of data transmission. Only motion area, rather than complete frame, required sending data to display, which can greatly improve data bandwidth. This is very useful for high-resolution display system since even low data rate can achieve the fast display refresh. This approach is a module-based design, which can easily be extended to any size with auto re-configuration without using embedded processor.

For many distributed power systems (DPSs) such as light-emitting diode lighting and battery management, communication is essential. This study presents an improved method of integrating power transfer and communication through a common bus by applying the concept of power/data time division multiplexing transmission (PD-TDMT). The proposed method employs power electronic topologies as the basic circuits to create the power transfer system and utilises the power transmission intervals for communication. Compared with conventional communication techniques in DPS, the proposed method has the advantages of simple implementation, enhanced noise immunity and higher output power capacity. The general structure of PD-TDMT systems is presented, which includes power sourcing equipment (PSE) and powered devices (PDs). A series of PSE and PD circuits are derived based on dc–dc topologies. The timing sequence of power transfer and communication is given. To suppress the common-mode interferences under the high-power condition, a balanced power transmission system is also proposed. Besides, the termination circuits are discussed in detail under the long-distance transmission condition. Finally, the proposed method and theoretical analysis are verified by experiment.

This research study investigates electrical performance of the multilayered organic light-emitting diode (OLED) with a focus on the role of charge injection, transport and emission layers. Device parameters; luminescence and current density are extracted using Silvaco ATLAS numerical device simulator and validated through the fabricated experimental results with a minor deviation of 3%. Furthermore, a mathematical model is applied to extract other device parameters such as electric field, charge carrier mobility, concentration and current density. Additionally, the multilayered device architecture is critically analysed through cut line methodology to better comprehend the internal device physics in terms of hole-electron mobility, concentration and their recombination. Subsequently, the performance parameters extracted using analytical model are compared with the results of internal analysis and a close match is observed. These results prove the Poole-Frenkel mobility-dependent behaviour in the OLEDs that varies following electric field. Analyses also highlight high electron and hole concentrations in the vicinity of the emission layer as a reason of high luminescence in the multilayered OLED, directly following the Langevin's theory of recombination in organic semiconductors. These analyses highlight the impact of different layers in the OLEDs and thus open up new horizons to further performance improvement in these devices.