According to the communication theory, only a limited amount of data can be transmitted within a given bandwidth for wireless communication. Ever since these limits were revealed 60 years ago, we have been trying to reach the boundaries determined by physics as efficiently as possible. In light of the growing significance of cellular phone networks and WLAN connections, scientists are seeking new ways to transfer more data than ever before – after all, transmission capacities are in short supply and, therefore, a valuable commodity.
Messages from the babble
Thanks to so-called MIMO technology, which stands for “Multiple Input Multiple Output”, it is possible for several transceivers to communicate with each other on the same bandwidth at the same time. Transceivers have several antennas. “It is as if several people are communicating with several other people”, explains Helmut Bölcskei, professor at the Communications Technology Laboratory at ETH Zurich. “At face value, it just seems like an incomprehensible babble. If the listeners skillfully combine the hubbub, however, they can filter out the original messages.” In terms of wireless communication, this means you can transfer far more information than with existing procedures.
Practical capability proven
ETH Zurich researchers had already furnished proof that MIMO technology works in a similar test facility three years ago – albeit with only one user. However, until recently it was still unclear as to whether and how the increase in capacity could be implemented in complex networks with several users. This is the aim of the European research pro-ject “MASCOT” (Multiple-Access Space-Time Coding Testbed), in which ETH Zurich is involved with its Communications Technology Laboratory and Integrated Systems Laboratory. It was with this in mind that the prototype developed at these two institutes was enhanced.
For the first time, the Zurich-based researchers were able to demonstrate that the principle of multiple antenna systems is actually feasible for use in complex wireless networks both theoretically and using their test facility. In doing so, they succeeded in constructing a compact multi-user system, currently with three stations in a bench scale, where every station transmits or receives via four antennae. This meant that the utilization of the frequency range for each of the three users could be up to four times higher than with present-day WLAN networks.
All set for WLAN applications
One crucial point of the research project was the development of procedures to unscramble the jumble of signals in the receiver as efficiently as possible. This presented the researchers with a problem: the more antennas and participants the system has, the more data that can in principle be transmitted; however, this also means that its demodulation is all the more difficult. As the antennas are meant to be installed in inexpensively manufactured equipment, the signals have to be decoded with as inexpensive a chip as possible, i.e. a small one. The smaller the chip, however, the smaller its computational power.
Thanks to a deeper understanding of the theoretical principles of multi-antenna systems, the researchers were able to develop efficient decoding algorithms that require a much smaller chip area. The receivers developed at ETH Zurich are currently so efficient that the new MIMO technology can easily be installed in commercially available laptops and WLAN stations.
It may be some time before MIMO technology is used in cellular phones as the antennas on hand to date require a certain distance for reliable data transfer. Consequently, the antennas have to be improved first.MIMO-Testbed
Roman Klingler | alfa
Fraunhofer FIT joins Facebook's Telecom Infra Project
25.10.2016 | Fraunhofer-Institut für Angewandte Informationstechnik FIT
Stanford researchers create new special-purpose computer that may someday save us billions
21.10.2016 | Stanford University
Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.
This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
27.10.2016 | Materials Sciences
27.10.2016 | Physics and Astronomy
27.10.2016 | Life Sciences