Terahertz Radio Breakthrough Pushes Multi-Gig Connections Over a Mile, Could Boost Rural Networks

Researchers from Northeastern University, working with the US Air Force, NASA, and Amazon, have developed a way to boost the range and bandwidth available in sub-terahertz and terahertz wireless communications systems — and say it could help bridge the "digital divide" and help to get rural areas connected.

"You need to find a technology that can give you optical-like connectivity without the optical problems, and we think that terahertz technology is that," Josep Jornet, associate professor of electrical and computer engineering, explains of the reason to look into terahertz wireless links in place of physical fiber that needs to be run in expensive trenches. "My research is driven by showing people that things they believe will not work can work."

Traditionally, high-bandwidth terahertz wireless communications have been limited to practically touching distance — owing to the signal becoming more fragile as the frequency increases. Jornet and colleagues, however, have managed to connect two stations a mile and a quarter apart with a multi-gigabit wireless link. The secret: a complete shift in the way the radio is set up.

The first step was to remove the mixer from the equation, feeding the information to be transmitted directly into the signal generator. "We don’t have a mixer that can handle this much power–fine, let’s not have a mixer," he explains, leaving the issue of distortion to handle. "Instead of trying to fix the information at the receiver, let me pre-distort my signal," he continues. "I'm going to make the signal ugly, such that when it goes through the source, it becomes beautiful."

In testing, the revised radio system worked perfectly — delivering two orders of magnitude improvements in usable frequency and bandwidth when compared with 5G radio systems. While the system still relies on line-of-sight for best performance, that may not be an issue for one of the biggest potential winners: rural users, where a point-to-point sub-terahertz or terahertz link based on the technology can be used as a backhaul for traditional cellular or Wi-Fi connections, avoiding the need to dig trenches and lay cable.

"As a scientist, my goal is to show that two kilometers [around 1.25 miles] was just the first stop," Jornet claims. "We want to go for space because that will also give connectivity to everyone. You will have connectivity like your Verizon Fios, independent of where you are in the world, just because you have a bunch of satellites orbiting the Earth with the right technology. It sounds crazy, but it's not any crazier than 10 years ago when you said you could [reach] two kilometers."

The team's work has been published under closed-access terms in the journal Nature Electronics.

Main article image courtesy of Matthew Modoono/Northeastern University.