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DMT modulation for VLC

: Langer, K.-D.


Arnon, S.:
Visible Light Communication
Cambridge: Cambridge University Press, 2015
ISBN: 978-1-107-44798-1 (print)
ISBN: 1-107-44798-4 (print)
ISBN: 1-316-24800-3
ISBN: 978-1-316-24800-3
ISBN: 1-336-05132-9
ISBN: 978-1-336-05132-4
ISBN: 1-107-06155-5 (online)
ISBN: 978-1-107-06155-2 (online)
Book Article
Fraunhofer HHI ()

Introduction Optical free space communication using visible radiation, i.e. light, has been known for a very long time. Some early examples are signaling using fire, the Heliograph using sunlight, which is directed to the receiver by means of a mirror, or the Photophone invented by Graham Bell (1880). Due to the outstanding success of radio technologies and due to their intrinsic benefits, up to now optical free space communication has remained a niche technology. One of such niche applications took advantage of the immunity from interception, namely the so-called directed transmission for military aims during World War 2 and later on. Different approaches such as optical wireless communication (OWC) using fluorescent tubes are also well recorded in the patent literature but have never achieved a breakthrough. A revival of this way of wireless communication has come about with the advent of visible light LEDs of increasingly high optical power. While their application i nitially was limited to signaling (e.g. telltale or warning light), at the turn of the millennium it became apparent that in future lighting would be dominated by LEDs. Henceforth, there has been growing interest in applications using LED-based OWC, or which combine the functions of lighting and optical wireless data transmission. At the same time, the common term Visible Light Communications (VLC) was coined for this kind of communication. The major reasons for the steadily rising interest in VLC are the lifetime and improved optical power of white light LEDs particularly, and their progressive adoption, as well as the simplicity of LED modulation via their driving current at a modulation bandwidth in the lower MHz range, see e.g. [1â3]. Moreover, the proliferation of mobile applications using radio frequencies has accentuated concerns about the adequate availability of radio-frequency bands and the limits of transmission capacity in current wireless networks, as well as the related data security i