A user equipment (UE) and a method for frame-based equipment (FBE) operation in an unlicensed band are provided. The method includes receiving, from a base station (BS), a first parameter indicating a first periodicity of a fixed frame period (FFP) used when the BS acts as an initiating device for the FBE operation; and receiving, from the BS, a second parameter indicating a second periodicity of the FFP used when the UE acts as the initiating device for the FBE operation.