A method for handling hybrid automatic repeat request, HARQ, operations for aggregated carriers comprising: determining a total number of soft buffer bits to be partitioned; obtaining a plurality of carrier-dependent weighting factors corresponding respectively to a plurality of aggregated carriers; and partitioning the total number of soft buffer bits based at least in part on the carrier-dependent weighting factors to obtain a plurality of soft buffer partitions, wherein partitioning the total number of soft buffer bits comprises selecting a soft buffer partition size based at least in part on at least one of: N IR, k = ⌊ N soft ∑ m = 0 C carrier − 1 K MIMO, m ⋅ W m ⋅ min M DL _ HARQ, m, M limit, m / W k ⌋, N IR, k = ⌊ N soft K MIMO, k ∑ m = 0 C carrier − 1 ⋅ W m ⋅ min M DL _ HARQ, m, M limit, m / W k ⌋, N IR, k = ⌊ N soft ∑ m = 0 C carrier − 1 K MIMO, m ⋅ N RB, m DL ⋅ min M DL _ HARQ, m, M limit, m / RB, k DL ⌋, or N IR, k = ⌊ N soft K MIMO, k ∑ m = 0 C carrier − 1 ⋅ N RB, m DL ⋅ min M DL _ HARQ, m, M limit, m / N RB, k DL ⌋, wherein N IR,k is the soft buffer memory partition size for the k th carrier; N soft is the total number of soft buffer bits for a specified UE category; N carrier is the total number of aggregated carriers; W m is a carrier-dependent relative weighting factor used as carrier dependent weighting factor for the m th carrier; N RB, m DL is a carrier bandwidth factor used as carrier dependent weighting factor and indicating the bandwidth of the m th carrier; K MIMO, m is the maximum number of transport blocks for the m th carrier that are transmittable to a user equipment device in one transmission time interval; M DL_HARQ, m is the maximum number of downlink hybrid automatic retransmit request processes for the m th carrier; and M limit,m is the configured maximum number of hybrid automatic retransmit request processes for the m th carrier. determining a total number of soft buffer bits to be partitioned; obtaining a plurality of carrier-dependent weighting factors corresponding respectively to a plurality of aggregated carriers; and partitioning the total number of soft buffer bits based at least in part on the carrier-dependent weighting factors to obtain a plurality of soft buffer partitions, wherein partitioning the total number of soft buffer bits comprises selecting a soft buffer partition size based at least in part on at least one of: N IR, k = ⌊ N soft ∑ m = 0 C carrier − 1 K MIMO, m ⋅ W m ⋅ min M DL _ HARQ, m, M limit, m / W k ⌋, N IR, k = ⌊ N soft K MIMO, k ∑ m = 0 C carrier − 1 ⋅ W m ⋅ min M DL _ HARQ, m, M limit, m / W k ⌋, N IR, k = ⌊ N soft ∑ m = 0 C carrier − 1 K MIMO, m ⋅ N RB, m DL ⋅ min M DL _ HARQ, m, M limit, m / RB, k DL ⌋, or N IR, k = ⌊ N soft K MIMO, k ∑ m = 0 C carrier − 1 ⋅ N RB, m DL ⋅ min M DL _ HARQ, m, M limit, m / N RB, k DL ⌋, wherein N IR,k is the soft buffer memory partition size for the k th carrier; N soft is the total number of soft buffer bits for a specified UE category; N carrier is the total number of aggregated carriers; W m is a carrier-dependent relative weighting factor used as carrier dependent weighting factor for the m th carrier; N RB, m DL is a carrier bandwidth factor used as carrier dependent weighting factor and indicating the bandwidth of the m th carrier; K MIMO, m is the maximum number of transport blocks for the m th carrier that are transmittable to a user equipment device in one transmission time interval; M DL_HARQ, m is the maximum number of downlink hybrid automatic retransmit request processes for the m th carrier; and M limit,m is the configured maximum number of hybrid automatic retransmit request processes for the m th carrier.