Positioning and advertising in large indoor environments using visible light communication

Este trabalho foi financiado pelo Concurso Anual para Projetos de Investigação, Desenvolvimento, Inovação e Criação Artística (IDI&CA) 2018 do Instituto Politécnico de Lisboa. Código de referência IPL/2018/LAN4CC_ISELWe investigate the applicability of an intuitive advertising system for large indoor environments using visible light communication (VLC). This VLC-based positioning system includes the use of the visible light signals to light the space and to transmit information for traveler positioning and for advertising campaigns in the surroundings. As transmitters, white RGB-LEDs were used. Although their original function is to provide illumination, due to the ability of each individual chip to switch quickly enough to transfer data, they were used to broadcast information. This functionality is used for communication where multiplexed data can be encoded in the emitting light. The light signals emitted by the LEDs, positioned in the area of an advertising campaign are interpreted directly by the customers’ receivers. A silicon carbide optical sensor with light filtering and demultiplexing properties receives the modulated signals containing the ID, the geographical position of the LED, and other information, and then it demultiplexes and decodes the data and locates the mobile device within the environment. Different layouts are analyzed; square and hexagonal meshes are tested, and a two-dimensional localization design, demonstrated by a prototype implementation, is presented. The key differences between both topologies are discussed. For both, the transmitted information, indoor position, and motion direction of the customer are determined. The results show that the LED-aided VLC navigation system enables to determine the position of a mobile target inside the network, to infer the travel direction as a function of time, and to interact with the received information.