Chair of Information and Coding Theory

Human Centric LiFi


Human centric lighting (HCL) is the framework of considering health, productivity, and emotional comfort of people by a personalized control of light sources. Light quality (including spectral contents, intensity, and timing of light exposure) is an essential recipe of HCL, and should be matched to our circadian rhythm. Working hours should be supported by cool light, working breaks and lunch time by reduced color temperature, and evening hours by warm light avoiding blue portions. Concerning the light sources, a consideration of the spectral power distribution over the entire visible range is important in the context of HCL. But also the positioning of the light sources (i.e., the directivities of the light waves) play an important role, as melanopsin-containing retinal ganglion cells are said to be concentrated in the lower half of the human retina. Hence, downlight is preferable. Besides health/productivity/emotional comfort, HCL has an often ignored impact on safety at work and at home.

Visible Light Communication (VLC) is an emerging wireless data transmission technology. Light is used simultaneously for illumination as well as for communication and/or positioning purposes. If fully networked, called Li-Fi, VLC systems complement Wi-Fi access points. VLC is an incident of optical wireless communications (OWC). OWC systems provide high data security, are license-free, and may substitute radio systems when these either fail or are not permitted. VLC technology enhances smart lighting infrastructure and Internet-of-Things (IoT) use cases.

The combination of HCL and VLC/Li-Fi has not yet been studied in detail, but it is believed that VLC is an enabling technique towards personalizing light quality. We are currently working on a system proposal that combines HCL and VLC/Li-Fi, coined human centric Li-Fi (HCLiFi) [1,2].


Selected References:

[1] P.A. Hoeher, Visible Light Communication: Theoretical and Practical Foundations. Munich: Hanser Fachbuch, accepted for publication, 2019.

[2] P.A. Höher and J. Mietzner, "Integrative Lichtqualität - Zukünftig mit sichtbarer Lichtkommunikation kombinierbar?" in Proc. LiTG Zukunftskonferenz Licht, Hamburg, Germany, May 2019.


The projects have been sponsored by: