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Beamforming antenna cancels interferer signals

Posted: 28 May 2014 ?? ?Print Version ?Bookmark and Share

Keywords:antenna? interferer? signal? beamforming? Internet?

A team of researchers from the University of Twente has designed an antenna that "looks at" wanted signals and "looks away" from interfering signals, thereby preventing 'malfunction', which happens when various devices transmit signals at the same location at the same time and on the same frequency.

The shortage of transmission frequencies is already a concern, and will continue to be such as the frequency spectrum gets more crowded. This causes several signals to use a single frequency, leading to what is called collisions between information, and wireless network delays.

Bram Nauta, a professor in Integrated Circuit Design at the University of Twente said: "At home we currently use one frequency for our laptop, router and telephone...But in a few years' time, our homes will have countless appliances that make use of frequencies. For instance, your coffee-maker will know you are about to arrive home and will start making you a cup of coffee. To do this, the coffee-maker will need a frequency. The same applies to masses of appliances. Our antenna offers a solution for the increasing shortage of frequencies."

The system builds on the beamforming technique. Instead of just one, four receivers are utilised to receive the desired signal with the same delay. These receivers also take in the interferer signal, although with different delays. Consequently, the desired signal gets maximum amplitude, while the interferer signal is cancelled. It also integrates adaptive allays to compensate for the different arrival times of the transmitter and interferer signals.

Michiel Soer, a postgraduate student at the university, fabricated a prototype chip that implements the beamforming hardware in the 65nm CMOS process.

Beamforming chip

Soer's beamforming chip design. Source: University of Twente

Nauta explained: "The malfunctioning signal is taken care of because the circuits on our chip process the incoming signals mathematically. The system can be compared to road traffic. The cars are little packages containing information. At the moment, 'traffic' is regulated with traffic lights and 'cars' have to wait for one another. The antenna that Michiel has designed has replaced the traffic lights with viaducts. The cars can carry on travelling, without bumping into one another or having to wait. This will make Internet faster."

In principle, the antenna is ready for use. It is expected to be available on the market within two years. The antenna could be used in laptops, tablets and routers. Eventually it will also be possible to use the antenna for other appliances, such as mobile telephones.

Soer explains how antenna beam forming can result in faster wireless connection for more users simultaneously. The setup consisted of: (1)the beamforming chip mounted on the PCB, which features four inputs for the four antennas in the array, (2)a transmitter with the desired signal, (3)and the interferer. Source: University of Twente

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