A user equipment comprising: a transmission unit configured to transmit a hybrid automatic repeat request-acknowledgement, HARQ-ACK, response for a serving cell; a higher layer processing unit; and a reception unit configured to receive a physical downlink control channel, PDCCH, or an enhanced physical downlink control channel, EPDCCH, with a first downlink control information, DCI, format for scheduling a physical downlink shared channel, PDSCH, or a second DCI format for scheduling a physical uplink shared channel, PUSCH; the higher layer processing unit notifies a base station apparatus of capability information of the user equipment, the capability information including information that indicates band(s) supporting time division duplex, TDD, - frequency division duplex, FDD, carrier aggregation; in a first case that the TDD-FDD carrier aggregation is configured and a TDD is applied to a primary cell, the HARQ-ACK response in an uplink subframe n is transmitted upon a detection of a PDSCH transmission within a subframe n-k for the secondary cell, where k is an element of a downlink association set, a downlink assignment index, DAI, field is present in the first DCI format for the secondary cell,and the DAI field is present in the second DCI format for the secondary cell with either TDD operation with uplink-downlink configuration 1-6 or FDD operation; in a second case that the TDD-FDD carrier aggregation is configured and an FDD is applied to the primary cell, the HARQ-ACK response in an uplink subframe m is transmitted upon a detection of a PDSCH transmission in a subframe m-4 for the secondary cell, the DAI field is not present in the first DCI format for the secondary cell, the DAI field is not present in the second DCI format for the secondary cell; and in a case that the HARQ-ACK response is transmitted through a physical uplink control channel, PUCCH, the HARQ-ACK response is transmitted though the PUCCH in the primary cell;_wherein a DAI in the DAI field of the first DCI format denotes an accumulative number of PDCCHs or EPDCCHs with assigned PDSCH transmissions, and PDCCHs or EPDCCHs indicating downlink semi-persistent scheduling, SPS, release among a plurality of downlink subframes corresponding to one uplink subframe in which HARQ response information can be transmitted; and a DAI in the DAI field of the second DCI format denotes the number of PDCCHs or EPDCCHs with assigned PDSCH transmissions, and PDCCHs or EPDCCHs indicating downlink SPS release among a plurality of downlink subframes corresponding to one uplink subframe in which HARQ response information can be transmitted. a transmission unit configured to transmit a hybrid automatic repeat request-acknowledgement, HARQ-ACK, response for a serving cell; a higher layer processing unit; and a reception unit configured to receive a physical downlink control channel, PDCCH, or an enhanced physical downlink control channel, EPDCCH, with a first downlink control information, DCI, format for scheduling a physical downlink shared channel, PDSCH, or a second DCI format for scheduling a physical uplink shared channel, PUSCH; the higher layer processing unit notifies a base station apparatus of capability information of the user equipment, the capability information including information that indicates band(s) supporting time division duplex, TDD, - frequency division duplex, FDD, carrier aggregation; in a first case that the TDD-FDD carrier aggregation is configured and a TDD is applied to a primary cell, the HARQ-ACK response in an uplink subframe n is transmitted upon a detection of a PDSCH transmission within a subframe n-k for the secondary cell, where k is an element of a downlink association set, a downlink assignment index, DAI, field is present in the first DCI format for the secondary cell,and the DAI field is present in the second DCI format for the secondary cell with either TDD operation with uplink-downlink configuration 1-6 or FDD operation; in a second case that the TDD-FDD carrier aggregation is configured and an FDD is applied to the primary cell, the HARQ-ACK response in an uplink subframe m is transmitted upon a detection of a PDSCH transmission in a subframe m-4 for the secondary cell, the DAI field is not present in the first DCI format for the secondary cell, the DAI field is not present in the second DCI format for the secondary cell; and in a case that the HARQ-ACK response is transmitted through a physical uplink control channel, PUCCH, the HARQ-ACK response is transmitted though the PUCCH in the primary cell;_wherein a DAI in the DAI field of the first DCI format denotes an accumulative number of PDCCHs or EPDCCHs with assigned PDSCH transmissions, and PDCCHs or EPDCCHs indicating downlink semi-persistent scheduling, SPS, release among a plurality of downlink subframes corresponding to one uplink subframe in which HARQ response information can be transmitted; and a DAI in the DAI field of the second DCI format denotes the number of PDCCHs or EPDCCHs with assigned PDSCH transmissions, and PDCCHs or EPDCCHs indicating downlink SPS release among a plurality of downlink subframes corresponding to one uplink subframe in which HARQ response information can be transmitted.