A method of a user equipment (UE) for controlling a signal comprises receiving configuration information for enabling or disabling a signal transmission, receiving a first physical downlink control channel (PDCCH) conveying a first downlink control information (DCI) format, decoding the first DCI format, determining whether the first DCI format is correctly decoded; and transmitting the signal or suspending a transmission of the signal according to the configuration information when the first DCI format is not correctly decoded.