Visible Light Communications

In recent years, visible light communications (VLC) has rapidly gained interest among research communities worldwide. It is an emerging technology for future high capacity communication links utilizing the visible range of the electromagnetic spectrum (~370-780 nm), which is not only licensed free but free from spectral overcrowding unlike radio frequencies (RF). VLC utilizes light-emitting diodes (LEDs), modulating them at high speeds that are much faster than the human eye can detect, to simultaneously provide data transmission and room illumination. A major challenge in VLC is the LED modulation bandwidths, which are limited to a few MHz.

Recently, we have been focused mainly on the signal processing techniques enabling effective utilization of the transmission bandwidth in VLC. We have adopted multi-band carrier-less amplitude and phase (m-CAP) modulation in VLC domain, originally developed for optical fibre networks, and proposed and verified a number of techniques improving m-CAP performance in terms of bit rate, spectral efficiencies, and computational complexity. Among inorganic LEDs, organic-based LEDs (OLEDs) represent a possible solution for solid-state lighting applications due to their advantage such as ultra-low costs, mechanical flexibility, and large photoactive areas. However, their modulation bandwidth is limited to a few hundreds of kHz introducing significant bottle-neck in VLC networks. Thus, we are also focused on equalization schemes that enhance VLC systems performance and are necessary for designing OLED based networks.

We have many international academic collaborations with world-leading research groups in the field of VLC, including Northumbria University and Newcastle University.

Optical camera communication (OCC) can be considered a convenient and versatile short-range communication technology within the framework of optical wireless communications. OCC is a pragmatic version of VLC based on a smart device camera that allows easier implementation of various services in smart devices. OCC can be a more favourable solution, especially in indoor environments, due to one compelling fact that the OCC is based on a camera as the receiver and nearly six billion smartphones fitted with cameras are available worldwide.

We have addressed the issue of longer processing time in OCC using neural network-based processing for applications such as motion detection over the existing OCC links. The motion detection is considered as an add-on functionality in OCC to control various smart devices in smart home environments. Recently we have focused on OCC System for Internet of Things based on OLEDs. Performance of outdoor OCC links using focusing and defocusing techniques for applications such as vehicle-to-vehicle communications is also performed in an outdoor environment. Currently, we are working on OCC link analysis to develop multiuser environment as well as to provide mobility in indoor OCC scenarios. Collaborative work with international academic institutes working in the same field gives a way out to interesting results for the ongoing research. Our international collaborators include academic research groups from the University of Las Palmas de Gran Canaria and Northumbria University.

Výzkumné skupiny

Bezdrátová a vláknová optika

Výzkumný tým se zabývá vláknovou optikou, optickou detekcí, vláknovými lasery, šířením optických svazků v zástavbě i uvnitř budov a vlivem atmosféry na bezdrátové optické spoje (free-space optics, FSO) a v neposlední řadě i komunikací ve viditelném světle - visible-light communication (VLC). V současné době je vědecká činnost týmu zaměřena jak na základní výzkum, tak i na spolupráci s průmyslem v oblasti aplikovaného výzkumu a experimentálního vývoje.

Za stránku zodpovídá: Ing. Mgr. Radovan Suk