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

Advances on CMOS image sensors

This paper offers an introduction to the technological advances of image sensors designed using complementary metal–oxide–semiconductor (CMOS) processes along the last decades. We review some of those technological advances and examine potential disruptive growth directions for CMOS image sensors and proposed ways to achieve them. Those advances include breakthroughs on image quality such as resolution, capture speed, light sensitivity and color detection and advances on the computational imaging. The current trend is to push the innovation efforts even further as the market requires higher resolution, higher speed, lower power consumption and, mainly, lower cost sensors. Although CMOS image sensors are currently used in several different applications from consumer to defense to medical diagnosis, product differentiation is becoming both a requirement and a difficult goal for any image sensor manufacturer. The unique properties of CMOS process allows the integration of several signal processing techniques and are driving the impressive advancement of the computational imaging. With this paper, we offer a very comprehensive review of methods, techniques, designs and fabrication of CMOS image sensors that have impacted or might will impact the images sensor applications and markets

On evolution of CMOS image sensors

CMOS Image Sensors have become the principal technology in majority of digital cameras. They started replacing the film and Charge Coupled Devices in the last decade with the promise of lower cost, lower power requirement, higher integration and the potential of focal plane processing. However, the principal factor behind their success has been the ability to utilise the shrinkage in CMOS technology to make smaller pixels, and thereby have more resolution without increasing the cost. With the market of image sensors exploding courtesy their inte- gration with communication and computation devices, technology developers improved the CMOS processes to have better optical performance. Nevertheless, the promises of focal plane processing as well as on-chip integration have not been fulfilled. The market is still being pushed by the desire of having higher number of pixels and better image quality, however, differentiation is being difficult for any image sensor manufacturer. In the paper, we will explore potential disruptive growth directions for CMOS Image sensors and ways to achieve the same

A review of gallium nitride LEDs for multi-gigabit-per-second visible light data communications

The field of visible light communications (VLC) has gained significant interest over the last decade, in both fibre and free-space embodiments. In fibre systems, the availability of low cost plastic optical fibre (POF) that is compatible with visible data communications has been a key enabler. In free-space applications, the availability of hundreds of THz of the unregulated spectrum makes VLC attractive for wireless communications. This paper provides an overview of the recent developments in VLC systems based on gallium nitride (GaN) light-emitting diodes (LEDs), covering aspects from sources to systems. The state-of-the-art technology enabling bandwidth of GaN LEDs in the range of >400 MHz is explored. Furthermore, advances in key technologies, including advanced modulation, equalisation, and multiplexing that have enabled free-space VLC data rates beyond 10 Gb/s are also outlined

Comunicações ópticas por câmera para sistemas de assistência à condução

Communications, whatever its type, is a pillar of our modern society. More specifically, communications by visible light, that show numerous advantages, from electromagnetic spectral efficiency and regulation freedom to energy saving (since it combine illumination and communication). As such, the automotive world is interested in this technology, in particularly, its application into the Intelligent Transport System (ITS). The objective of this work relies on the study and development of a demonstrator able to support VLC communication means in V2V (Vehicle to Vehicle) scenario, making use of the LED luminaries already implemented in nowadays cars. Since the outdoor implementation is one of the requirements, reception based in OCC (Optical Camera Communication) is a viable solution in this conditions. Also the signal processing/decoding is performed by a CNN (Convolutional Neural Network), this type of algorithm shows a huge decoding flexibility and resilience, which benefits the transmission system performance. All the project was done in collaboration with the integrated circuits systems group of Instituto de Telecomunicações de Aveiro and Exatronic Lda company, based in Aveiro and specialized in innovation and investigation (I+I), engineering and manufacturing of electronics.As comunicações, qualquer que seja o seu tipo, mostram-se como um pilar fundamental para a sociedade. Especificamente as comunicações por luz visível, que apresentam inúmeras vantagens, desde a eficiência espectral e mais liberdade de regulamentação, até à energética pois alia duas caracteristicas distintas (iluminação e comunicação) numa só. Como tal, o mundo automóvel apresenta-se como um dos posíveis interessados na aplicação desta tecnologia, mais propriamente a aplicação como parte integrante do sistema inteligente de transportes (ITS). Este trabalho tem como objectivo o estudo e desenvolvimento de um demonstrador capaz de estabelecer um link de comunicação V2V (Vehicle to vehicle) por meio da modulação da luz visivel emitida pelas iluminárias LED já equipadas actualmente nos veículos. Sendo a implementação exterior um dos requerimentos deste sistema, a rececção através de OCC (Optical Camera Communication) mostra-se assim uma solução viável. Assim como o processamento do sinal recebido, que é efectuado por meio de CNNs (Convolutional Neural Networks), que mostram flexibilidade e resiliência, o que benefecia a capacidade do sistema de transmissão. Todo o projecto foi realizado em colaboração com o grupo de circuitos integrados do Instituto de Telecomunicações de Aveiro e a empresa Exatronic Lda, sediada em Aveiro, e especializada em inovação, investigação (I+I), engenharia e produção de eletrónica.Mestrado em Engenharia Eletrónica e Telecomunicaçõe