"Who would pay for unlicensed spectrum? That's a great question," Brodsky said. "If no one did, under this bill, there would be no unlicensed spectrum."

Current uses of unlicensed spectrum include Wi-Fi devices, cordless phones and baby monitors, and the proposal would not take away existing unlicensed spectrum. But innovation and experimentation in unlicensed spectrum would "screech to a grinding halt," Feld said. "Given that unlicensed uses like Wi-Fi come from small and new companies, the future of new uses would be very bleak."

A committee spokeswoman didn't immediately respond to a request for comments on the Public Knowledge criticism.

The Wireless Innovation Alliance, with members including Microsoft, Google and Dell, also raised concerns about the proposal. The proposal to auction unlicensed spectrum would "hamper the development of new and innovative unlicensed products and services," the group said in a statement.