Methods and apparatus for performing HARQ performed by a user equipment (UE) are provided. A bundling indicator is received which indicates the number of bundled downlink subframes, and a determination is made whether at least one bundled downlink subframe is missed by comparing the bundling indicator with the number of detected bundled downlink subframes. A representative ACK/NACK signal is generated when no bundled downlink subframe is missed, and the representative ACK/NACK signal is transmitted on an uplink channel. Recovery capability is maximized and packet loss is reduced so that fewer ACK/NACK signals are fed back than downlink packets.