Patent attributes
A user equipment includes a receiver configured to receive a PDSCH and a transmitter configured to transmit a HARQ-ACK response for a serving cell. In a first case that the user equipment communicates with at least a serving cell having a duplex mode that is TDD, the transmitter is configured to transmit, in a primary cell, the HARQ-ACK response in an uplink subframe n upon detection of a PDSCH transmission in the serving cell within a subframe n−k. In a second case that the user equipment communicates with a primary cell and a secondary cell, duplex mode of the primary cell being FDD, the transmitter is configured to transmit, in the primary cell, the HARQ-ACK response in an uplink subframe m upon detection of a PDSCH transmission in the secondary cell in only a subframe m−4.