Studium vlastností optické bezvláknové datové sítě pro vnitřní prostory v oblasti viditelného optického záření.

Abstract

The wireless networks represent progressively developed area of information technologies. They allow to the people to be more flexible, because they can’t be fixed in their homes or offices, but they can share information with other people during travelling in the train, car or even during walking on the street. The wireless networks enable better availability of the services then conventional wiring connection. The new dynamic direction of wireless networks development is based on the idea of networks utilizing the optical radiation in the visible spectrum VLC (Visible Light Communications). The impulse of this development direction was improvement in the semiconductor lighting technologies, namely the white power LEDs (Light Emitting Diode). These types of wireless networks are denoted as the optical wireless networks for indoor spaces utilizing optical radiation in the visible spectrum. The first research results in this area were concluded by the IEEE standard 802.15.7 (modulations VPPM, OOK and CSK) in 2011. The aim of this thesis is to observe current research trends. It is mainly problematic of multipath propagation during hybrid connection in between transceiver and receiver with direct visibility LOS and variation of optical power during data transmission for higher modulation formats. The theoretical part of this thesis includes summary of wireless networks, is closely dealing with optical wireless networks and also with mathematical description of optical wireless networks channel for indoor spaces utilizing optical radiation in visible spectrum. The theoretical part is dealing with mathematical description and software modulation of the optical transmitter cell operating in visible radiation range and also with mathematical description of the modulation formats influence on difficulties caused by multipath propagation. Practical part is aimed at experimental verification of modulation formats influence on problems caused by multipath propagation, verification of modulation formats influence on optical power variation. This part is also including suggestions for variations elimination and optical power control in case of multistate modulation formats.