Terahertz receiver for 6G wireless communications

Date:
September 8, 2020
Source:
Karlsruher Institut fu"r Technologie (KIT)
Summary:
Future wireless networks of the 6th generation (6G) will consist
of a multitude of small radio cells that need to be connected
by broadband communication links. In this context, wireless
transmission at THz frequencies represents a particularly attractive
and flexible solution.

Researchers have now developed a novel concept for low-cost
terahertz receivers.



FULL STORY ========================================================================== Future wireless networks of the 6th generation (6G) will consist
of a multitude of small radio cells that need to be connected by
broadband communication links. In this context, wireless transmission
at THz frequencies represents a particularly attractive and flexible
solution. Researchers at Karlsruhe Institute of Technology (KIT) have now developed a novel concept for low-cost terahertz receivers that consist
of a single diode in combination with a dedicated signal processing
technique. In a proof-of-concept experiment, the team demonstrated
transmission at a data rate of 115 Gbit/s and a carrier frequency of
0.3 THz over a distance of 110 meters. The results are reported in
Nature Photonics.


==========================================================================
5G will be followed by 6G: The 6th generation of mobile communications
promises even higher data rates, shorter latency, and strongly increased densities of terminal devices, while exploiting Artificial Intelligence
(AI) to control devices or autonomous vehicles in the Internet-of-Things
era. "To simultaneously serve as many users as possible and to transmit
data at utmost speed, future wireless networks will consist of a large
number of small radio cells," explains Professor Christian Koos, who
works on 6G technologies at KIT together with his colleague Professor
Sebastian Randel. In these radio cells, distances are short such that
high data rates can be transmitted with minimum energy consumption and
low electromagnetic immission. The associated base stations will be
compact and can easily be mounted to building facades or street lights.

To form a powerful and flexible network, these base stations need to be connected by high-speed wireless links that offer data rates of tens or
even hundreds of gigabits per second (Gbit/s). This may be accomplished
by terahertz carrier waves, which occupy the frequency range between
microwaves and infrared light waves. However, terahertz receivers are
still rather complex and expensive and often represent the bandwidht
bottleneck of the entire link. In cooperation with Virginia Diodes (VDI)
in Charlottesville, USA, researchers of KIT's Institute of Photonics and Quantum Electronics (IPQ), Institute of Microstructure Technology (IMT),
and Institute for Beam Physics and Technology (IBPT) have now demonstrated
a particularly simple inexpensive receiver for terahertz signals.

Highest Data Rate Demonstrated So Far for Wireless THz Communications
over More Than 100 Meters "At its core, the receiver consists a
single diode, which rectifies the terahertz signal," says Dr. Tobias
Harter, who carried out the demonstration together with his colleague
Christoph Fu"llner in the framework of his doctoral thesis. The diode
is a so-called Schottky barrier diode, that offers large bandwidth and
that is used as an envelope detector to recover the amplitude of the
terahertz signal. Correct decoding of the data, however, additionally
requires the time-dependent phase of the terahertz wave that is usually
lost during rectification. To overcome this problem, researchers use
digital signal processing techniques in combination with a special
class of data signals, for which the phase can be reconstructed from the amplitude via the so-called Kramers-Kronig relations. The Kramers-Kronig relation describe a mathematical relationship between the real part and
the imaginary part of an analytic signal. Using their receiver concept,
the scientists achieved a transmission rate of 115 Gbit/s at a carrier frequency of 0.3 THz over a distance of 110 m.

"This is the highest data rate so far demonstrated for wireless terahertz transmission over more than 100 m," Fu"llner says. The terahertz receiver developed by KIT stands out due to its technical simplicity and lends
itself to cost-efficient mass production.


========================================================================== Story Source: Materials provided by
Karlsruher_Institut_fu"r_Technologie_(KIT). Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. T. Harter, C. Fu"llner, J. N. Kemal, S. Ummethala, J. L. Steinmann,
M.

Brosi, J. L. Hesler, E. Bru"ndermann, A.-S. Mu"ller, W. Freude, S.

Randel, C. Koos. Generalized Kramers-Kronig receiver for
coherent terahertz communications. Nature Photonics, 2020; DOI:
10.1038/s41566- 020-0675-0 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200908122517.htm

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