Design and implementation of an uplink connection for a light-based IoT node

Abstract. In the wake of soaring demand for shrinking radio frequency (RF) spectrum, light-fidelity (LiFi) has been heralded as a solution to accommodate resources for future communication networks. Infrared (IR) and visible light communication (VLC) are meant to be used within LiFi because of numerous advantages. By combining the paradigm of internet of things (IoT) along with LiFi, light-based IoT (LIoT) emerges as a potential enabler of future 6G networks. With tremendous number of interconnected devices, LIoT nodes need to be able to receive and transmit data while being energy autonomous. One of the most promising clean energy sources comes from both natural and artificial light. In addition to providing illumination and energy, light can also be utilized as a robust information carrier. In order to provide bidirectional connectivity to LIoT node, both downlink and uplink have to be taken into consideration. Whereas downlink relies on visible light as a carrier, uplink approach can be engineered freely within specific requirements. With this in mind, this master’s thesis explores possible solutions for providing uplink connectivity. After analysis of possible solutions, the LIoT proof-of-concept was designed, implemented and validated. By incorporating printed solar cell, dedicated energy harvesting unit, power-optimised microcontroller unit (MCU) and light intensity sensor the LIoT node is able to autonomously transmit data using IR

A Survey of Positioning Systems Using Visible LED Lights

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.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.Peer reviewe

Simulation, performance and interference analysis of multi-user visible light communication systems

The emergence of new physical media such as optical wireless, and the ability to aggregate these new media with legacy networks motivate the study of heterogeneous network performance, especially with respect to the design of protocols to best exploit the characteristics of each medium. This study considers Visible Light Communications (VLC), which is expected to coexist with legacy and future radio frequency (RF) media. While most of the research on VLC has been done on optimizing the physical medium, research on higher network layers is only beginning to gain attention, requiring new analyses and tools for performance analysis. The first part of the dissertation concerns with developing a new ns3-based VLC module that can be used to study VLC-RF heterogeneous networks via simulation. The proposed ns3 module is developed based on existing models for intensity modulated LED signals operating as lighting units transmitting to optical receivers at indoor scales (meters). These models and the corresponding simulation model are validated using a testbed implemented with a software-defined radio (SDR) system, photodetector, phosphor-converted “white” LEDs, and under PSK and QAM modulation. Two scenarios are used in the validation of the VLC module: (i) using a receiver placed right bellow the transmitter with varying range, and (ii) using a receiver with a fixed range and varying angle of acceptance. Results indicate good correspondence between the simulated and actual testbed performance. Subsequently, it demonstrates how the VLC module can be used to predict the performance of a hybrid WiFi/VLC network simulated using the ns3 environment with UDP, TCP, and combined network traffic. The second part of the dissertation focuses on modeling interference at VLC system level based on variable pulse position modulation (VPPM) and variable on-off keying (VOOK) which are used in VLC to simultaneously provide lighting with dimming control as well as communication. The bit error performance of these modulation schemes is evaluated at VLC systems consisting of multiple transmitters-receivers pairs, where co-channels interference exists. The BER is derived by providing an in depth analysis that captures the signal structure of the interference in terms of the number of transmitters. This work dispenses with the Gaussian interference model which is not suitable when the number of interferers are few and the central limit theorem (CLT) cannot be applied. The result shows that under realistic small-room scenario, the analytical results closely match with that of simulation

Software-Defined Lighting.

For much of the past century, indoor lighting has been based on incandescent or gas-discharge technology. But, with LED lighting experiencing a 20x/decade increase in flux density, 10x/decade decrease in cost, and linear improvements in luminous efficiency, solid-state lighting is finally cost-competitive with the status quo. As a result, LED lighting is projected to reach over 70% market penetration by 2030. This dissertation claims that solid-state lighting’s real potential has been barely explored, that now is the time to explore it, and that new lighting platforms and applications can drive lighting far beyond its roots as an illumination technology. Scaling laws make solid-state lighting competitive with conventional lighting, but two key features make solid-state lighting an enabler for many new applications: the high switching speeds possible using LEDs and the color palettes realizable with Red-Green-Blue-White (RGBW) multi-chip assemblies. For this dissertation, we have explored the post-illumination potential of LED lighting in applications as diverse as visible light communications, indoor positioning, smart dust time synchronization, and embedded device configuration, with an eventual eye toward supporting all of them using a shared lighting infrastructure under a unified system architecture that provides software-control over lighting. To explore the space of software-defined lighting (SDL), we design a compact, flexible, and networked SDL platform to allow researchers to rapidly test new ideas. Using this platform, we demonstrate the viability of several applications, including multi-luminaire synchronized communication to a photodiode receiver, communication to mobile phone cameras, and indoor positioning using unmodified mobile phones. We show that all these applications and many other potential applications can be simultaneously supported by a single lighting infrastructure under software control.PhDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/111482/1/samkuo_1.pd

Visible Light Optical Camera Communication for Electroencephalography Applications

Due to the cable-free deployment and flexibility of wireless communications, the data transmission in the applications of home and healthcare has shown a trend of moving wired communications to wireless communications. One typical example is electroencephalography (EEG). Evolution in the radio frequency (RF) technology has made it is possible to transmit the EEG data without data cable bundles. However, presently, the RF-based wireless technology used in EEG suffers from electromagnetic interference and might also have adverse effects on the health of patient and other medical equipment used in hospitals or homes. This puts some limits in RF-based EEG solutions, which is particularly true in RF restricted zones like Intensive Care Units (ICUs). As a recently developed optical wireless communication (OWC) technology, visible light communication (VLC) using light-emitting diodes (LEDs) for both simultaneous illumination and data communication has shown its advantages of free from electromagnetic interference, potential huge unlicensed bandwidth and enhanced data privacy due to the line transmission of light. The most recent development of VLC is the optical camera communication (OCC), which is an extension of VLC IEEE standard 802.15.7, also referred to as visible light optical camera communication (VL-OCC). Different from the conventional VLC where traditional photodiodes are used to detect and receive the data, VL-OCC uses the imaging camera as the photodetector to receive the data in the form of visible light signals. The data rate requirement of EEG is dependent on the application; hence this thesis investigates a low cost, organic LED (OLED)-driven VL-OCC wireless data transmission system for EEG applications

Light sensor development for ARA platform

Some years ago Google announced the ARA initiative. This consist on a modular phone where parts of the phone, like cameras, sensors or networks can be changed. So when a new feature appears or requiered by the user it is not needed to change the mobile phone, just to buy the modules with the functionality. See https://www.youtube.com/watch?v=2pr9cV6lvws for further information. The Wireless Networks Group will receive in December a developement kit (http://projectara.com/s/ProjectAraSpiral1DeveloperHardwareManual.pdf), to start working with it on January. The PFC or MasteDuring the last years, Visible Light Communication (VLC), a novel technology that enables standard Light-Emitting-Diodes (LEDs) to transmit data, is gaining significant attention. In the near future, this technology could enable devices containing LEDs – such as car lights, city lights, screens and home appliances – to carry information or data to the end-users, using their smartphone. However, VLC is currently limited by the end-point receiver, such as a the mobile camera, or a peripheral connected through the jack input and to unleash the full potential of VLC, more advanced receiver are required. On other, few year ago, Google ATAP - the Google innovation department - announced the ARA initiative. This consist on a modular phone where parts of the phone, like cameras, sensors or networks can be changed. So when a new feature appears or required by the user it is not needed to change the mobile phone, just to buy the modules with the functionality. This Master Thesis presents the design and development of a simple module that will support communication by light (VLC) using the ARA Module Developer Kit provided by Google. It consists on building a front-end circuit, connecting a photodiode that receives the level of light and use it as data carrier, in order to receive and display data inside a custom Android application on the ARA smartphone

Spatial and wavelength division multiplexing for high-speed VLC systems: An overview

White light emitting diodes (LEDs) are becoming the primary source of illumination for the home and office environment. These LEDs can be intensity modulated to transmit high-speed data via an optical carrier. As a result, there is a paradigm shift in indoor wireless communication as the illumination infrastructure can be reused for data communications. It is widely expected that visible light communication (VLC) system will play a significant role in realizing the high-speed data communication envisaged for 5G connectivity. The goal of VLC systems is to provide a reliable and ubiquitous communication link that is an order of magnitude faster than current radio frequency (RF) links. In order to support the high data rates required for the current and future generations of communication systems, a number of techniques were explored for VLC by a number of research groups worldwide. This paper provides an overview of spatial and wavelength division multiplexing that has enabled multi-Gb/s transmission speeds in VLC using low bandwidth LEDs