Speeding up WLAN

A European project could prevent future internet gridlock by applying a method to quadruple the transmission rate of conventional networks from 54Mbps to as much as 216Mbps.



One of the areas the Multiple-Access Space-Time Coding Testbed (MASCOT) project is focused on is wireless local area networking (WLAN). WLAN uses modulation technology based on radio waves to enable communication between devices in a limited area. Until now, it was believed that only a limited amount of data could be transmitted within a given bandwidth for wireless communication.



MASCOT uses so-called MIMO (Multiple Input Multiple Output) technology to boost transmission speed. This technology makes it possible for several transceivers to communicate with each other on the same bandwidth at the same time.



The transceivers have several antennae. Rather than providing jumbled up signals, the researchers were able to demonstrate that the principle of multiple antenna systems is feasible for use in complex wireless networks. At their test site, they constructed a compact multi-user system, with three stations in bench scale, where every station transmits or receives via four antennas. This meant that the use of the frequency range for each of the three users could be up to four times higher than with present-day WLAN networks.



‘It is as if several people are communicating with several other people,’ said Prof Helmut Bölcskei of ETH Zurich, the project coordinator. ‘At face value, it just seems like an incomprehensible babble. If the listeners skilfully 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 systems.



Applying 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 by the project consortium are currently so efficient that the MIMO technology can be installed in commercially-available laptops and WLAN stations.