Researchers at the Karlsruhe Institute of Technology (KIT) in Baden-Württemberg, Germany, have set a new wireless transmission record, achieving speeds that are truly “flash” fast.
Installing cable-based telecommunications infrastructure is expensive and often impractical, particularly for remote and rural locations. Those areas frequently remain underserved or unconnected because extending fiber or copper networks can be prohibitively costly.
Using broadband data transmission through radio relay links offers a lower-cost, more flexible alternative. Radio-based backhaul can extend high-capacity connectivity into places where laying cable is not economically feasible, helping close the digital divide.
In the recent laboratory demonstration, the team transmitted 100 gigabits per second at a carrier frequency of 237.5 GHz over a 20-meter link. That throughput and frequency combination represents a significant advance in high-frequency wireless communication.
The previous record in this area came from an earlier experiment within the same “Millilink” initiative, also supported by the German Federal Ministry of Education and Research (BMBF). That demonstration achieved 40 gigabits per second, but over a much longer 1-kilometer link between rooftops in Karlsruhe’s city center.
It’s important to note the new 100 Gbps result is reported for a single data stream. Modern radio systems can combine multiple streams and employ spatial multiplexing and other techniques to multiply total capacity, so aggregate bandwidth could be substantially higher without compromising signal integrity.
To reach the 100 Gbps milestone, the researchers used a photonic approach to generate the high-frequency radio signal at the transmitter end. After transmission, the receiver relied on fully integrated electronic circuits to process the incoming signal. This hybrid photonic-electronic technique leverages the advantages of photonics for ultra-high-frequency generation and of electronics for compact, efficient receiver implementation.
Professor Ingmar Kallfass supervised the Millilink research while holding a joint professorship supported by the Fraunhofer Institute for Applied Solid State Physics (IAF) and KIT. Since early 2013 he has continued related research at the University of Stuttgart.
Professor Kallfass highlights the practical potential: “For rural areas in particular, this technology represents an inexpensive and flexible alternative to optical fiber networks, whose extension can often not be justified from an economic point of view.”
He adds a tangible example of the capacity: “At a data rate of 100 gigabits per second, it would be possible to transmit the contents of a Blu-ray disc—or the equivalent of five DVDs—between two devices in about two seconds by radio.”
The Millilink projects are backed by the German government with funding of nearly $3 million, supporting research into millimeter-wave and sub-terahertz wireless links that could complement or substitute for fiber in specific scenarios.
These demonstrations point toward practical implementations such as high-capacity wireless backhaul for mobile networks, last-mile connectivity to rural communities, temporary high-bandwidth links for events or disaster response, and dense urban links where fiber deployment is difficult. Challenges remain—particularly link range, atmospheric propagation at very high frequencies, and cost-effective commercialization—but the progress shows promising directions for expanding broadband access.
What do you think about these projects? Could they have useful real-world applications?