Technology to support mapping for Hybrid Automatic Retransmission re-Quest (HARQ) for Carrier Aggregation (CA) is disclosed. One method can include a user equipment (UE) identifying, within a radio frame, a type 2 DownLink (DL) sub-frame within a virtual bundling window associated with a Secondary Component Carrier (SCC). The type 2 DL sub-frame can be virtually moved from a Primary Component Carrier (PCC) for HARQ-ACKnowledge (HARQ-ACK) multiplexing of the virtual bundling window. The UE can extract a Component Carrier Element (CCE) number for a first CCE used by a Physical Downlink Control CHannel (PDCCH) transmission corresponding to the type 2 DL sub-frame. The UE can determine a Physical Uplink Control CHannel (PUCCH) resource for carrying a HARQ-ACK multiplexing message based on the CCE number when a PCC window size of the PCC is greater than an SCC window size of the SCC.