Theoretische Grundlagen der Kommunikationstechnik

Invitation to a Talk by Dr. rer. nat. Volker Jungnickel (Fraunhofer HHI, TU Berlin)

Time27 November 2015, 10:30 AM  
LocationHFT - Hochfrequenztechnik building, 6th floor, Room HFT-TA 617, Einsteinufer 25, 10587 Berlin  
TitleAn Introduction Into Optical Wireless Communications  


Optical Wireless Communications has a long history. While free-space optical point-to-point links are well known, the use of optical wireless became popular since high-power light-emitting devices (LEDs) are widely used for lighting nowadays. The idea of visible light communication is to offer wireless access via the LED-based lighting infrastructure. Optical wireless has many applications, such as nomadic access in home and office scenarios, industrial automation, vehicular communication and as a backhaul of small radio cells. Because of these use cases, standardization activities are ongoing in the IEEE 802.15.7r1 task group and the G.vlc initiative at ITU.

The talk provides an introduction into recent research in this area, including low-cost transmitter and receiver design, channel modeling, adaptive transmission based on discrete multi-tone and other waveforms and wavelength-division multiplexing (WDM). Under normal illumination conditions, Gbit/s data rates can be reached despite the limited modulation bandwidth of LEDs. Luminaries can be deployed in overlapping and non-overlapping scenarios. If used for mobile communications, accordingly, horizontal handover between luminaries, combined with interference management, and vertical handover to another wireless technology, such as WiFi, are needed. While the corresponding system concepts look very similar to 5G mobile radio, there are specific differences, such as the real-valued, non-negative waveform unlike complex-valued, bipolar waveforms used for radio. For the capacity of a single link, an upper bound is known which can be applied to frequency-selective channels. However, little is known concerning multiple-input multiple-output channels, relevant for the desired use cases with many distributed luminaries and wireless users. Accordingly, no limit is known for the performance of algorithms, and no design rules based on fundamental results.

More theoretical research is obviously needed, besides standards and practical deployment, in order to achieve the best performance in future optical wireless networks. The talk is intended to establish a common understanding between experimental and theoretical researchers, to stimulate an open discussion of what information theory and experimental research could do together and to identify the most interesting research topics in this emerging field.



Volker Jungnickel received diploma and doctorate degrees in physics from HU Berlin, in 1992 and 1995, respectively, and the habilitation degree in communication engineering in 2015 from TU Berlin. He worked on semiconductor quantum dots and laser medicine before joining Fraunhofer Heinrich Hertz Institute in 1997 where he is currently leading the metro-, access-, and in-house systems group. Since 2003, Volker served as adjunct lecturer at TU Berlin. He contributed to high-speed optical wireless links, the first 1 Gb/s MIMO-OFDM mobile radio transmission, the first implementation and field trial of LTE, and the first coordinated multipoint experiments, all in real-time. His current research is directed to optical wireless again as well as converged fixed and wireless access and high-speed optical transmission over short distances. Volker authored and co-authored 180 conference and journal papers, 10 book chapters and holds 25 patents, quoted nearly 4.000 times in Google Scholar. He won best paper awards at PIMRC 2004, VTC 2010, VTC 2013, and the patent award at HHI in 2006. He served as program chair of WSA 2009, Track Chair for VTC 2007 and 2013, on numerous TPCs, and Associate Editor for IEEE PTL in 2014.