Embodiments of the disclosure provide a method and apparatus for performing data transmission in a HARQ procedure. The method may comprise: transmitting first transmission of a data block to a receiver, wherein a data channel of the first transmission is carried on a first component carrier; in response to receiving from the receiver a negative acknowledge message indicating the first transmission is failed, determining a second component carrier for retransmission of the data block based on carrier availability; and performing the retransmission on the second component carrier.