User equipment of an LTE system, comprising: a receiving module, configured to receive more than one piece of first downlink control information sent by a base station, wherein each piece of first downlink control information carries a downlink assignment index, and more than one piece of the first downlink control information further carries a total downlink assignment index; a processing module, configured to generate a hybrid automatic repeat request, HARQ, response message according to the total downlink assignment index, the downlink assignment index of each piece of first downlink control information, and a physical downlink shared channel corresponding to each piece of first downlink control information; and a sending module, configured to send the hybrid automatic repeat request response message to the base station, wherein a total quantity of ACKs and NACKs in the HARQ response being the same as the total downlink assignment index; each downlink assignment index is used to indicate an index of a physical downlink shared channel corresponding to downlink control information carrying the downlink assignment index and a physical downlink control channel indicating downlink semi-persistent scheduling release; and the total downlink assignment index is a sum of a quantity of physical downlink shared channels corresponding to all downlink control information and a quantity of physical downlink control channels indicating downlink semi-persistent scheduling release; wherein the receiving module is configured to: obtain a hybrid automatic repeat request response message bit quantity threshold supported on a pre-defined physical uplink control channel; and the sending module is configured to: if the total downlink assignment index is greater than the hybrid automatic repeat request response message bit quantity threshold supported on the physical uplink control channel, send the hybrid automatic repeat request response message to the base station by using a physical uplink control channel format 4; or if the total downlink assignment index is less than or equal to the hybrid automatic repeat request response message bit quantity threshold supported on the physical uplink control channel, send the hybrid automatic repeat request response message to the base station by using a physical uplink control channel format 3. a receiving module, configured to receive more than one piece of first downlink control information sent by a base station, wherein each piece of first downlink control information carries a downlink assignment index, and more than one piece of the first downlink control information further carries a total downlink assignment index; a processing module, configured to generate a hybrid automatic repeat request, HARQ, response message according to the total downlink assignment index, the downlink assignment index of each piece of first downlink control information, and a physical downlink shared channel corresponding to each piece of first downlink control information; and a sending module, configured to send the hybrid automatic repeat request response message to the base station, wherein a total quantity of ACKs and NACKs in the HARQ response being the same as the total downlink assignment index; each downlink assignment index is used to indicate an index of a physical downlink shared channel corresponding to downlink control information carrying the downlink assignment index and a physical downlink control channel indicating downlink semi-persistent scheduling release; and the total downlink assignment index is a sum of a quantity of physical downlink shared channels corresponding to all downlink control information and a quantity of physical downlink control channels indicating downlink semi-persistent scheduling release; wherein the receiving module is configured to: obtain a hybrid automatic repeat request response message bit quantity threshold supported on a pre-defined physical uplink control channel; and the sending module is configured to: if the total downlink assignment index is greater than the hybrid automatic repeat request response message bit quantity threshold supported on the physical uplink control channel, send the hybrid automatic repeat request response message to the base station by using a physical uplink control channel format 4; or if the total downlink assignment index is less than or equal to the hybrid automatic repeat request response message bit quantity threshold supported on the physical uplink control channel, send the hybrid automatic repeat request response message to the base station by using a physical uplink control channel format 3. obtain a hybrid automatic repeat request response message bit quantity threshold supported on a pre-defined physical uplink control channel; and the sending module is configured to: if the total downlink assignment index is greater than the hybrid automatic repeat request response message bit quantity threshold supported on the physical uplink control channel, send the hybrid automatic repeat request response message to the base station by using a physical uplink control channel format 4; or if the total downlink assignment index is less than or equal to the hybrid automatic repeat request response message bit quantity threshold supported on the physical uplink control channel, send the hybrid automatic repeat request response message to the base station by using a physical uplink control channel format 3.