The invention relates to methods and apparatuses for providing HARQ feedback in a mobile communication system using carrier aggregation. To suggest a scheme for transmitting feedback on the successful/unsuccessful decoding of transmissions that is operable in FDD mode, the invention proposes to utilize only a single one of plural radio resources available for feedback transmission for signaling feedback for multiple transmissions. A feedback sequence of ACK/NACKs for the transmissions is mapped to one feedback resource combination that is one of the radio resources available for feedback transmission and a modulation symbol of the given modulation scheme that is transmitted on said one radio resource. This scheme can also be used in cases where the number of possible feedback sequences of ACK/NACKs for the transmissions is larger than the number of feedback resource combinations available for feedback transmission.