Google is trying to secretly test a 6GHz network in 17 different states, according to a batch of FCC filings spotted by Business Insider. But exactly what Google is trying to test is unclear.

Here’s a few things we do know. Google wants to experiment with 6GHz spectrum to “produce technical information relevant to the utility of these frequencies for providing reliable broadband connections.” The company also says it expects the experiments to take place over 24 months, and has asked permission to do the tests in 26 cities and towns across 17 states — including Arizona, California, Colorado, Florida, Georgia, Illinois, Iowa, Kansas, Nebraska, Nevada, New York, North Carolina, Oklahoma, Oregon, Texas, Utah, and Virginia.

Beyond that, there’s not a lot we can tell from these documents — and there are a lot of possibilities for what Google might want with that 6GHz spectrum. The “providing reliable broadband connections” language could suggest that Google wants to experiment with some kind of home internet service — perhaps a potential future offering under the Google Fiber Webpass banner.

But Google could have other uses for that 6GHz spectrum as well. Only recently did the FCC approve a plot of unlicensed 6GHz spectrum, and any number of things could take advantage of that. Wi-Fi 6E routers might run at 6GHz, as could vehicle-to-vehicle communication, and the latest 5G specifications suggest unlicensed 6GHz spectrum could even be used for 5G cellular networks. Google’s not limited to existing ideas, though — it’s called unlicensed spectrum for a reason.

The thing to know about 6GHz is that it’s expected to allow for faster and more reliable connections — it can carry more bandwidth than the 2.4GHz or 5GHz connections you might already be familiar with, and there could be less wireless interference between devices as well. But just like 5GHz Wi-Fi offers shorter range than 2.4GHz Wi-Fi, it’s likely that 6GHz networks will have shorter range still.

We don’t know what Google’s working on right now. But the filings tell us Google is hoping to use that newly-opened 6GHz spectrum for some sort of “secret commercially valuable plan,” and we’re pretty curious what that might be.