A user equipment, UE, is configured to receive downlink control information, DCI, transmitted to the UE by a primary cell in a wireless communication system. The UE comprises one or more processing circuits that shall assume that a DCI message which has a common payload size and the same first control channel element index, but different bit fields, in a common search space and a UE-specific search space is transmitted by the primary cell in the common search space or the UE-specific search space, based on radio resource control, RRC, configuration of the UE.