23 May 2016

ACCESS project achieves record 6Gb/s terrestrial radio transmission over 37km

The collaborative project ACCESS (Advanced E Band Satellite Link Studies) has set a record in terrestrial radio transmission, achieving a data rate of 6Gb/s over a distance of 37km (exceeding the state of the art by a factor of 10).

Comprising a research group headed by professor Ingmar Kallfass from the Institute of Robust Power Semiconductor Systems (ILH) at the University of Stuttgart, the Institut für Hochfrequenztechnik und Elektronik (IHE) at the Karlsruhe Institute of Technology (KIT), industrial partner Radiometer Physics GmbH (A Rohde & Schwarz Company), and the Fraunhofer Institute for Applied Solid State Physics IAF, the ACCESS team realised the record data transmission on a stretch between stations located on the 45-storey Uni-Center in Cologne and the site of the Space Observation Radar TIRA at the Fraunhofer Institute for High Frequency Physics and Radar Techniques FHR in Wachtberg 36.7km away.

The high data rate of 6Gb/s was achieved by using efficient transmitters and receivers at radio frequencies of 71–76GHz in the E-band (regulated for terrestrial and satellite broadcasting). Only in this millimeter-wave frequency range are the required high effective bandwidths available. A further difficulty is the weake­ning of the signals over larger dis­tances. The transmission must be espe­cially powerful, and the amplifiers must be correspondingly efficient. The key to the unique combination of gigabit data rates and great distance is efficient transmitters and re­cei­vers in the form of fully monolithically integrated millimetre-wave cir­cuits (MMICs) based on two different transistor technologies developed and manufactured by project partner Fraunhofer IAF.

In the transmitter the broadband signals are amplified to a comparatively high transmission power of up to 1W with the help of power amplifiers based on gallium nitride (GaN). A highly directive parabolic antenna emits the signals. Built into the receiver are low-noise amplifiers (LNAs) based on high-speed transistors using indium gallium arsenide (InGaAs) layers with very high electron mobility, ensuring the detection of the weak signals at great distance.

Radio transmission of high amounts of data over great distance serves many important application areas. For example, the next generation of satellite communication requires an ever-increasing data offload from earth observation satellites down to earth. The trial shows that supplying rural areas and remote regions with fast Internet is possible: 250 Internet connections can be supplied with 24Mb/s ADSL. Terrestrial radio transmissions in the E-band are suitable as a cost-effective replacement for the deployment of optical fiber or as ad-hoc networks in the case of crises and catastrophe, and for connecting base-stations in the backhaul of mobile communication systems.

The ever-increasing demand for higher data rates in fiber-based and wireless communication networks can only be met by technical innovations in network infrastructure. Developments such as the Internet of Things and Industry 4.0 are still in their early stages, and will demand unprecedented aggregated data quantities. Their processing and transmission in cloud-based services is already taking the communication infrastructure to its limits. In satellite communication as well, the progress in earth observation and space research as well as plans for a planet-scale satellite network are leading to as-yet unsolved challenges for the communication infrastructure.

The ACCESS project was completed at the end of April and is being continued in the follow-up project ELIPSE (E-band Link Platform and Test for Satellite Communication), targeting the next generation of communication ­sys­tems for the fast connection of satellites. However, a further application lies in terrestrial fixed wireless links.

The ACCESS project was funded by the Federal Ministry for Economy and Energy (BMWi) on the basis of a resolution by the German Bundestag. Support was provided by Fraun­hofer FHR, the Uni-Center Cologne and the Südwest-Rundfunk (SWR), who granted access to their buildings.

Tags: IAF E-band MMICs

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