Disclosed is a user equipment in a wireless communication system, configured to receive a first initial transmission associated with a first Hybrid Automatic Repeat Request (HARQ) process; receive a second initial transmission associated with a second HARQ process; and receive at least one retransmission associated with the first HARQ process, wherein when the second initial transmission occurs before the at least one retransmission, the second HARQ process assigned an HARQ process ID that is different from an HARQ process ID assigned to the first HARQ, and wherein when the second initial transmission occurs after the at least one retransmission, the second HARQ process assigned an HARQ process ID that is the same as an HARQ process ID assigned to the first HARQ process.