German researchers have managed to transmit 100 gigabits of data per second over a 20m distance in laboratory conditions, setting a new world record in wireless data transmission.
Such a data transmission speed would make it possible to transmit all contents of a full Blu-ray disk or five DVDs within less than two seconds.
“Our project has focused on integration of a broadband radio relay link into fibre-optical systems,” explained Professor Ingmar Kallfass, who has coordinated the project – a joint venture of the Fraunhofer Institute for Applied Solid State Physics (IAF) and the Karlsruhe Institute of Technology (KIT).
“For rural areas in particular, this technology represents an inexpensive and flexible alternative to optical fibre networks, whose extension can often not be justified from an economic point of view.”
In an article published in a recent issue of Nature Photonics, the team describes their method of using laser-based photonics to generate radio signals in a transmitter. To increase the capacity of the transmission, several bits of data have been combined into so-called data symbols and transmitted at the same time. The receiver, on the other side of the system, relies on integrated electronic circuits to capture the radio waves.
“It is a major advantage of the photonic method that data streams from fibre-optical systems can be directly converted into high-frequency radio signals,” said Professor Jürg Leuthold who oversaw the project on behalf of KIT.
“This advantage makes the integration of radio relay links of high bit rates into optical fibre networks easier and more flexible,“ he said.
The transmitter uses an ultra-broadband device, a photon mixer, to generate the radio signals using two optical laser signals of different frequencies superimposed on a photodiode.
The resulting electrical signal has a frequency equalling the sum of both default optical signals and can be radiated via an antenna. In contrast to a purely electronic transmitter, no intermediate electronic circuit is needed.
“Due to the large bandwidth and the good linearity of the photon mixer, the method is excellently suited for transmission of advanced modulation formats with multiple amplitude and phase states. This will be necessary in future fibre-optical systems,” Leuthold added.
Earlier this year, the team managed to transmit data at the rate of 40 gigabits per second over a 1km distance across the Karlsruhe city centre. Both experiments were part of the on-going Millilink project – funded through Germany’s Broadband Access Networks of the Next Generation research framework.
“The long transmission distances in Millilink were reached with conventional antennas that may be replaced by fully integrated miniaturized antenna designs in future compact systems for indoor use,” said Professor Thomas Zwick, from the KIT, emphasising the present data transmission rate could be further increased.
The team believes it is possible to improve the system up to the capacity of 1 terabit per second.
Broadband data transmission via radio relay links is widely considered as one of the most convenient means to help wireless networks bridge rivers, motorways or nature protection areas. Unlike cable-based communication networks, wireless transmission doesn’t require building expensive infrastructure and is therefore more economically feasible