A method and a UE apparatus for radio resource management in a mobile communication system. When a discontinuous reception period or an inactivity period of a UE exceeds a threshold, an ENB releases resources for uplink control information transmission allocated to the UE, and the UE recognizes the release of the resources and stops transmitting the uplink control information through the resources. This reduces the explicit reconfiguration procedure through an RRC message, which is otherwise necessary whenever the UE enters a new discontinuous reception mode.