MIT’s “Smart Wallpaper” of RF Antennas and Switches Boosts Wi-Fi Without Power

February 05, 2020 by Robin Mitchell

Researchers at MIT have created an RF wall, dubbed “smart wallpaper,” that consists of thousands of miniature RF antennas connected to RF switches.

Extending Wi-Fi signals, especially for IoT devices, can be expensive and difficult to install. But a new technology coming out of MIT called RFocus could change this with its no-power, beamforming capabilities.


RFocus smart wallpaper

RFocus includes 3,000 small, inexpensive antennas that "amplify nearby wireless signals." Image used courtesy of Jason Dorfman/CSAIL and MIT

The Trouble With Extending Wi-Fi

The researchers recognized the need to improve Wi-Fi strength but also acknowledged the limited options designers have to improve Wi-Fi presently. However, each option presents major drawbacks:

1) Designers can extend Wi-Fi with repeaters, but these devices can be expensive to implement and can potentially create security flaws in the network.

2) Designers can deploy RF antennas on receiving devices to improve their reception capabilities, but this option may not be possible for the majority of Wi-Fi devices that already feature integrated antennas or PCB-type antennas. 

3) Designers can choose an entirely different technology, such as 5G, which private owners will be able to deploy, effectively creating their own private cell network. However, such technologies are yet to be delivered to the masses and require modification to currently-installed hardware.

Researchers from MIT's Computer Science and Artificial Intelligence Laboratory (CSAIL) are presenting a fourth option—one they believe will extend connectivity at a reasonable cost. 


Meet RFocus

To get around the problems of creating new Wi-Fi repeaters, a team at MIT has been experimenting with beamforming techniques to improve Wi-Fi reception. However, unlike traditional beamforming techniques, the MIT team has created an RF wall, dubbed “smart wallpaper,” that consists of thousands of miniature RF antennas connected to RF switches.


MIT researcher Venkat Arun

MIT researcher Venkat Arun and "smart wallpaper." Image used courtesy of Jason Dorfman/CSAIL and MIT

Using Miniature Antennas as a Mirror

What makes RFocus radically different to most RF beamforming solutions is that RFocus is not an RF emitter and does not use any power for RF generation. Instead, RFocus uses the many miniature antennas on its surface as either RF reflectors or RF transmitters by controlling the RF switch connected to them.

The ability to reflect or transmit incoming RF signals allows RFocus to act as a mirror and reflect incoming Wi-Fi signals to specific points, thereby increasing the received signal by up to a factor of 10. Experimental results of RFocus show that it can also increase the channel capacity of the Wi-Fi network by up to two times.


How Does RFocus Work?

In order to work, RFocus requires that the receiving device record the current signal strength and then relay that to a software system, which applies complex algorithms to make adjustments to the RF array.

The construction of RFocus is very simple. Because it can be easily scaled, Wi-Fi networks can be potentially increased at a fraction of the cost of installing dedicated Wi-Fi repeaters. What makes the implementation of RFocus more accessible is that the RF antenna can be printed onto ultrathin materials, making it easier and cheaper to transport and install.


What's Next for RFocus?

RFocus is a technology that exploits beamforming, which is quickly becoming an important technique in modern RF design. If successful, RFocus could help to improve Wi-Fi signals in all environments, ranging from the home to the office without having to consume more power and RF channel space.