A method for a UE for performing a HARQ feedback operation for an SPS transmission is disclosed. The method comprises receiving a transmission configuration for a scheduled transmission, the transmission configuration indicating a first number of HARQ processes used for the scheduled transmission; receiving an SPS transmission configuration for an SPS transmission, the SPS transmission configuration indicating a second number of HARQ processes used for the SPS transmission; receiving scheduling signaling including a reserved HARQ process number for indicating that a HARQ state feedback operation for the scheduled transmission is disabled; determining a first HARQ process number corresponding to the SPS transmission, the first HARQ process number being selected according to the second number of HARQ processes and being equivalent to the reserved HARQ process number; and transmitting a HARQ state feedback for the SPS transmission with a second HARQ process number derived according to the first HARQ process number.