Just imagine the following scenario: four people are comfortably ensconced in a room. Each one of them can watch a film from the Internet on his or her laptop, in HD quality. This is made possible thanks to optical WLAN. Light from the LEDs in the overhead lights serves as the transfer medium.
In the future data will be transferred to laptops with the help of LEDs. (© Fraunhofer HHI)
For a long time, this was just a vision for the future. However, since scientists from the Fraunhofer Institute for Telecommunications, Heinrich Hertz Institute HHI in Berlin, Germany, have developed a new transfer technology for video data within the scope of the OMEGA project of the EU, its implementation in real life is getting markedly closer. At the end of May, the scientists were able to present the results of the project in Rennes, France.
They were able to transfer data at a rate of 100 megabits per second (Mbit/s) without any losses, using LEDs in the ceiling that light up more than ten square meters (90 square feet). The receiver can be placed anywhere within this radius, which is currently the maximum range. “This means that we transferred four videos in HD quality to four different laptops at the same time,“ says Dr. Anagnostis Paraskevopoulos from the HHI.
“The fundamentals of visible light communication (VLC) were developed together with the industry partners Siemens and France Telecom Orange Labs,“ said the expert. At HHI, the team of project manager Klaus-Dieter Langer is now further developing the new technology. “For VLC the sources of light – in this case, white-light LEDs – provide lighting for the room at the same time they transfer information. With the aid of a special component, the modulator, we turn the LEDs off and on in very rapid succession and transfer the information as ones and zeros. The modulation of the light is imperceptible to the human eye. A simple photo diode on the laptop acts as a receiver.
As Klaus-Dieter Langer explains, “The diode catches the light, electronics decode the information and translate it into electrical impulses, meaning the language of the computer.“ One advantage is that it takes only a few components to prepare the LEDs so that they function as transfer media. One disadvantage is that as soon as something gets between the light and the photo diode (for example, when someone holds his hand over the diode) the transfer is impaired. Laptops, Palm devices or mobile telephones are all potential end devices.
The scientists emphasize that VLC is not intended to replace regular WLAN, PowerLAN or UMTS. It is best suited as an additional option for data transfer where radio transmission networks are not desired or not possible – without needing new cables or equipment in the house. Combinations are also possible, such as optical WLAN in one direction and PowerLAN for the return channel. Films can be transferred to the PC like this and also played there, or they can be sent on to another computer.
The new transmission technology is suitable for hospitals, for example, because radio transmissions are not allowed there. Despite this fact, high data rates must be transmitted without losses and unzipped, according to the experts. If part of the communication occurs via the light in the surgical room, this would make it possible to control wireless surgical robots or transmit x-ray images. In airplanes, each passenger could view his own entertainment program on a display, saving aircraft manufacturers miles of cables. Another possible venue for the application of this technology are production facilities, where radio transmissions very often interfere with the processes.
Currently the scientists are developing their systems toward higher bit rates. “Using red-blue-green-white light LEDs, we were able to transmit 800 Mbit/s in the lab,“ said Klaus-Dieter Langer. “That is a world record for the VLC method.“ The HHI scientists will showcase how videos are transmitted by light in Hall 11.1, Booth 8 at the International Telecommunications Fair IFA (Internationale Funkausstellung IFA) in Berlin from September 2-7, 2011.
Dr. rer. nat. Anagnostis Paraskevopoulos | Fraunhofer-Institut
Stable magnetic bit of three atoms
21.09.2017 | Sonderforschungsbereich 668
Drones can almost see in the dark
20.09.2017 | Universität Zürich
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
22.09.2017 | Life Sciences
22.09.2017 | Medical Engineering
22.09.2017 | Physics and Astronomy