Princeton researchers are tackling a known challenge to unlocking 5G’s full potential: mmWave blocking. According to Princeton University, the device in development (mmWall) can steer mmWave signals to reach all corners of a large room.
Kun Woo Cho, a Ph.D. student in Princeton’s Department of Computer Science and the lead author of the research, said outdoor 5G base stations could someday replace WiFi systems and provide high-speed connectivity both indoors and outdoors, preventing glitches when devices switch between networks. She added that boosting 5G signals with technology like mmWall will be crucial to this broader adoption.
mmWall is about the size of a small tablet and is an accordion-like array of 76 vertical panels. The device can both reflect and refract radio waves at frequencies above 24 gigahertz. These frequencies can provide a bandwidth of 5 to 10 times greater than the maximum of 4G networks. mmWall can steer beams around obstacles, establishing connections quickly and maintaining them seamlessly. The device can bring signals from an outdoor transmitter indoors when installed in a window.
Senior study author Kyle Jamieson, a professor of computer science who leads the Princeton Advanced Wireless Systems Lab, explained that “wireless transmissions at these higher frequencies resemble beams of light more than a broadcast in all directions” and are more easily blocked by obstacles. The mmWall surface is the first to be able to “refract transmissions that hit one side of the surface, through at a different angle of departure, and is fully electronically reconfigurable within microseconds, allowing it to keep up with the ‘line rate’ of tomorrow’s ultra-fast networks,” he added.
The construction of the mmWall — two meandering lines of thin copper wire flanking a line of 28 broken circles made of thicker wire (meta-atoms) — allows the device to change the behavior of mmWave signals that interact with it. It dynamically steers the signals around obstacles by shifting their paths by up to 135 degrees. “We can basically steer to any angle for transmission and reflection,” explained Cho.
Cho tested mmWall in a 900-square-foot lab space at Pricenton’s computer science building. When a transmitter was placed indoors, she found that mmWall improved the signal-to-noise ratio at nearly all 23 locations tested around the room. When the transmitter was placed outdoors, mmWall boosted signals all around the room, including in roughly 40 percent of spots that had been completely blocked.
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