An apparatus and a method therein include selecting a size of a soft buffer memory partition per component carrier in a Carrier Aggregation scenario. The method supports multiple carriers to select a size of a soft buffer memory partition, the partition associated with receiving data on at least one component carrier, the multi-carrier system comprising at least two component carriers, each component carrier is associated with a configured bandwidth, the apparatus comprising the processor configured to select a size of a soft buffer memory partition for the first component carrier based at least in part on a first total number of soft channel bits, a first number associated with hybrid automatic retransmit request processes, and the configured bandwidth of the first component carrier.