External ‘smart surface’ boosts wireless signals for IoT devices

Technology News | February 11, 2020

By Rich Pell

The solution is designed to address the need for faster internet speeds, which up to now has been mostly addressed by simply adding antennas to either the transmitter – i.e., Wi-Fi access points and cell towers – or the receiver (such as a phone or laptop). But, say the researchers, that’s become increasingly difficult as devices – including a new wave of internet of things (IoT) systems – continue to shrink in size.

Rather than focusing on the transmitters and receivers, the researchers instead looked at amplifying the signal by adding antennas to an external surface in the environment itself. Their system, called RFocus, is a cost-effective two-dimensional surface that uses over 3,000 inexpensive antennas costing only a few cents each that don’t process the signal at all but merely control how it is reflected.

The project, say the researchers, likely represents the largest number of antennas ever used for a single communication link. According to the researchers, tests showed that RFocus could improve the average signal strength by a factor of almost 10.

While the system could serve as another form of WiFi range extender, say the researchers, its most valuable use could be in the network-connected homes and factories of the future.

“The core goal here was to explore whether we can use elements in the environment and arrange them to direct the signal in a way that we can actually control,” says MIT Professor Hari Balakrishnan, senior author of a new paper about RFocus. “If you want to have wireless devices that transmit at the lowest possible power, but give you a good signal, this seems to be one extremely promising way to do it.”

The state of the antenna elements on the surface is set by a software controller that the researchers developed with the goal of maximizing the signal strength at a receiver.

“The biggest challenge was determining how to configure the antennas to maximize signal strength without using any additional sensors, since the signals we measure are very weak,” says PhD student Venkat Arun, lead author of the new paper on the project. “We ended up with a technique that is surprisingly robust.”

Similar approaches to improving internet speeds using the external environment have been explored, including one proposed by a team at Princeton University led by Professor Kyle Jamieson, which was for the specific situation of people using computers on either side of a wall. However, say the researchers, the goal with RFocus was to develop an even more low-cost approach that could be used in a wider range of scenarios.

Jamieson, who was not involved in the RFocus project, adds, “Smart surfaces give us literally thousands of antennas to play around with. The best way of controlling all these antennas, and navigating the massive search space that results when you imagine all the possible antenna configurations, are just two really challenging open problems.”

The paper on the RFocus project will be presented next month at the USENIX Symposium on Networked Systems Design and Implementation (NSDI) in Santa Clara, California.