A method, performed by a user equipment (UE), of transmitting uplink data is provided. The method includes receiving, from a base station, configuration information for an uplink resource; determining a Hybrid Automatic Repeat Request (HARQ) process based on the configuration information; starting a configured grant timer (CGT) and a configured grant retransmission timer (CGRT) when uplink data corresponding to the HARQ process is transmitted; restarting the CGRT when the uplink data corresponding to the HARQ process is retransmitted; receiving, from the base station, downlink feedback information (DFI); and stopping the CGT and the CGRT based on the DFI indicating whether the base station received the uplink data.