The radio-frequency spectrum is a natural resource used to provide an array of wireless communications services that are critical to the U.S. economy and national security, such as mobile voice and data services, radio and television broadcasting, radar, and satellite-based services. Demand for radio-frequency spectrum has exploded over the past several decades as new technologies and services have been and continue to be brought to the market in the private sector and new mission needs unfold among government users of spectrum, including wireless communications critical for public safety...