Technology for conditional hybrid automatic retransmission re-quest (HARQ) mapping for carrier aggregation (CA) is disclosed. One method can include a user equipment (UE) determining when a subframe for physical downlink shared channel (PDSCH) transmission is configured for downlink semi-persistent scheduling (SPS). The subframe configured for downlink SPS can generate a first condition. The UE can generate HARQ-ACK states for the first condition for a HARQ bundling window with discontinuous transmission (DTX) padding for a secondary HARQ bundling window size for a secondary cell (SCell) and a primary HARQ bundling window size for a primary cell (PCell). The UE can generate HARQ-ACK states for a second condition for the HARQ bundling window with DTX padding including a DTX padding exception. The second condition can include conditions not covered by the first condition. The DTC padding exception can generate a set of HARQ-ACK states to uniquely define each padded HARQ-ACK state.