Future 6G networks promise blistering speeds, but there's a catch. The wireless channels they'll rely on can't pass through walls. But now, engineers have designed a workaround that could help solve one of the technology's biggest obstacles.

The next generation of cellular network technology is expected to lean heavily on millimeter waves — a sliver of the electromagnetic spectrum that can carry huge amounts of data but with wavelengths so short that they struggle to pass through solid objects like walls and furniture.

That's very different from the lower-frequency signals used by Wi-Fi and older cellular networks like 5G and 4G, which travel through obstacles far more easily. The result is patchy indoor coverage ‪—‬ a major roadblock for any technology that depends on millimeter waves.

But engineers think they've found an inexpensive workaround in the form of thin, 3D-printed tiles that reflect millimeter-wave signals around obstacles instead of trying to punch through them. The researchers outlined their technology, dubbed "FlowForm," in a new study published Aug. 11 in the journal Association for Computing Machinery. They also presented these findings Aug. 19 at the ACM SIGCOMM 2026 conference in Denver.

Reflective 6G

6G, which is expected to be rolled out in the 2030s, promises a theoretical maximum data-transfer speed of up to 1 terabit per second — approximately 3,000 times faster than average 5G speeds. But before the technology can be introduced, problems like its wireless signals being blocked by physical barriers must be resolved.

Each 6-by-6-inch (15 by 15 centimeters) tile is packed with thousands of engineered features smaller than the wavelengths themselves. These elements passively redirect incoming signals in specific directions.

Once they're created and mounted onto surfaces, the tiles require no power source, no wiring and no software updates. They just need to be fixed to a wall or ceiling.

FlowForm tiles perform two different roles inspired by the way small streams feed into rivers, but in reverse: Some tiles relay signals in long "major" chains across a room and around obstacles, while others "flow" outward, fanning coverage into the areas where people actually are.

"Our work demonstrates that a collective set of passive surfaces can make millimeter wave networks robust in real-world environments," Xinyu Zhang, a professor of electrical and computer engineering at the University of California, San Diego and co-author of the study, said in a statement.

When tested across five real indoor environments, the tiles nearly doubled average data rates and more than doubled the coverage area in tricky spaces, the scientists said. These included cluttered offices and rooms with awkward layouts, and the performance was on a par with today's leading fix for the problem, called active reconfigurable intelligent surfaces. Those systems use powered, electronically steerable panels that can cost thousands of dollars apiece, the scientists said. The new tiles, by contrast, cost around $2 each.

The system also works for people on the move, the scientists said. Wireless access points already scan for the best signal path many times per second, and with tiles covering a room from multiple angles, there's almost always a good reflected path available, wherever someone is standing. That means the tiles slot into existing networks with no new hardware or software required.

The researchers have filed a provisional patent and said they're open to partnering with companies interested in bringing the tiles to market.