A method, base station, and user equipment (UE) for radio communication in a radio communication system including a base station and a UE, the UE communicating with the base station in carrier aggregation mode over plural component carriers. The method includes: the base station assigns a priority to each component carrier according to at least one of the following rules to enable the UE to select, on overlapped uplink subframes, the component carrier having highest priority for uplink signal transmission, the rules including: desired power loss of uplink signal transmission over the component carrier, burden of uplink signal transmission over the component carrier, number of uplink subframes of the component carrier, and primary/secondary attributes of the component carrier for transmission of a downlink signal corresponding to the uplink signal transmitted over the component carrier. The method, base station, and UE can flexibly adjust the transmission carrier of a PUCCH.