Research team claims world record for wireless bandwidth
The high-speed data transfer has been accomplished between a 45-story high-rise building in Cologne and the campus of the space observation radar TIRA at the Fraunhofer Institute for Radio Frequency Physics and Radar Technology (FHR) near the town of Wachtberg. For its transmission, the researchers utilized the frequency band between 71 and 76 GHz – the E-band dedicated to terrestrial and satellite communications. Only in this frequency band the high bandwidth required for such data rates is available.
A challenge for wireless communications in this frequency range is the pronounced signal reduction over large distances, requiring high transmitting power and sophisticated amplifier circuits at the receiving side. Key to resolving this challenge were sophisticated, highly integrated microwave receiver and transmitter circuits (MMICs). These ICs are based on two innovative transistor technologies developed and manufactured by project partner Fraunhofer IAF. In the transmitter, the broadband signals have been amplified to a comparatively high power level of 1 watt by means of gallium nitride semiconductors. The signals then were transmitted through a highly effective directional antenna. The receiver utilizes ultra-high-speed indium-gallium arsenide semiconductors that feature an extraordinarily high electron mobility, resulting in very low noise generation in the amplifier circuitry.
Wireless broadband data transfer across large distances could be useful for many innovative applications and services. For instance, the next generation of earth observation satellites will trigger a flood of data between satellite and the earth station. Likewise, the supply of remote and rural areas with fast internet services is becoming more and more important. With the technology demonstrated at the Cologne trial, it would be possible to provide up to 250 subscribers with 24 Mbps ADSL services. Terrestrial e-band radio links is also regarded as a cost-efficient alternative to glass fiber.
Besides the university of Stuttgart, the Fraunhofer Institute for applied solid-state physics (Fraunhofer IAF) and the Karlsruhe Institute of Technology, Rohde & Schwarz subsidiary Radiometer Physics GmbH was involved in the project.
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