Four years ago, the FCC floated the concept of "interference temperature" as a way to have unlicensed transmitters share licensed bands without causing harmful interference. Rather than merely regulate transmitter power at fixed levels, as in the past, the scheme would have governed transmitter power on a variable basis calculated to limit the energy at victim receivers, where interference actually occurs.
The plan had a great many variables and unknowns.
A less ambitious proposal for the short term would have tried out a much-simplified form of the idea in two bands used by the fixed microwave service. Groups that use those bands, including the Fixed Wireless Communications Coalition, vigorously opposed.
The FCC has now agreed the whole idea was short on merit to begin with, and has dropped all forms of the proposal.
The order is at this link.