An access point (AP) device for controlling spectrum usage of a hierarchical communication system, in which a spectrum reserved for an Incumbent is usable by at least one user equipment (UE) for transmission when the spectrum is not required by the Incumbent, is disclosed. The AP device includes a processor configured to receive a message from the Incumbent requesting vacating of a spectrum; generate a group of users affected by the message from the Incumbent requesting vacating of the spectrum; and perform a spectrum management operation on the group of users.