40 Gbit Fast Wireless Data Transmission Marks New World Record

A wireless transmission with 40 Gbit/s over a distance of one kilometer, achieved by researchers of the Fraunhofer Institute for Applied Solid State Physics and the Karlsruhe Institute for Technology, Germany, set a new world record and ties in seamlessly with the capacity of optical fiber transmission. In the future, such radio links will be able to close gaps in providing broadband internet by supplementing the network in rural areas and places which are difficult to access.

Digital, mobile and networked – changing media usage habits of modern society require the faster transmission of increasing volumes of data. Broadband radio links can help to connect areas that are difficult and costly to reach by fiber networks, thereby facilitating the expansion of the network infrastructures. In rural areas they can be a cost-effective and flexible alternative to “Fiber to the Home”, especially when they deliver comparable speeds of many Gigabits per second.

For the first time, fully integrated electronic transmitters and receivers have been developed for a frequency of 240 GHz, which allows the transmission of data rates of up to 40 Gbit/s. This equals the transmission of a complete DVD in under a second or 2400 DSL16000 internet connections. Distances of over one kilometer have already been covered by using a long range demonstrator, which the Karlsruhe Institute of Technology set up between two highrises as part of the project “Millilink”.

“We have managed to develop a radio link based on active electronic circuits, which enables similarly high data rates as in fiber-optic systems, therefore allowing seamless integration of the radio link”, says Prof. Ingmar Kallfass, who coordinated the project at Fraunhofer IAF within the scope of a Shared Professorship between IAF and KIT.

Using the high frequency range between 200 and 280 GHz not only enables the fast transmission of large volumes of data, but also results in very compact technical assembly. Since the size of electronic circuits and antennae scales with frequency / wavelength, the transmitter and receiver chip only measures 4 x 1.5 mm². The semi-conductor technology developed at Fraunhofer IAF, based on transistors with high carrier mobility (HEMT), makes it possible with active transmitters and receivers in tiny, single integrated circuits.

Up to now, radio links were not able to directly transmit the data rates of glass fiber. This might change in the future, as the test setup of the project shows. Such a high performance system would also have the advantage of the so-called bit transparency, i.e. the signal of a glass fiber could be fed directly and without energy-consuming transcoding into a radio link. It could then be transmitted and redirected into a glass fiber. The record data from the test setup is only the beginning. “Improving the spectral efficiency by using more complex modulation formats or a combination of several channels, i.e. multiplexing, will help to achieve even higher data rates”, says Antes. This could give new impetus to the expansion of the broadband network.