Apparatus and method for transmitting data in wireless communication system

A base station in a wireless communication system, the base station comprising:

• at least one transceiver;
• and
• at least one processor, comprising processing circuitry, coupled with the at least one transceiver,
• wherein the at least one processor is configured to:
• transmit first data based on a first hybrid automatic request (HARQ) process at a transmission time of the first HARQ process;
• generate, by a MAC layer entity, mapping information regarding a relationship between the first HARQ process and the first data;
• before receiving a result of reception of the first data, transmit second data based on the first HARQ process with a new data indicator (NDI) indicating that the second data is a new data and is not retransmission of the first data, at a next transmission time of the first HARQ process;
• receive the result of reception of the first data indicating negative-acknowledgement (NACK);
• identify the first data based on the mapping information and the NACK;
• generate third data for retransmitting the first data;
• and
• transmit the third data based on a second HARQ process which is different from the first HARQ process,
• wherein the mapping information comprises an identifier (ID) of the first HARQ process, an identifier (ID) on the first data, a packet of the first data, and timing information regarding a time when a Protocol Data Unit (PDU) or Service Data Unit (SDU) is delivered through the first HARQ process ID.

A non-transitory computer-readable storage medium comprising instructions which, when executed by a base station of a wireless communication system including at least one processor, cause the base station to:

• transmit first data based on a first hybrid automatic request (HARQ) process at a transmission time of the first HARQ process;
• generate, by a MAC layer entity, mapping information regarding a relationship between the first HARQ process and the first data;
• before receiving a result of reception of the first data, transmit second data based on the first HARQ process with a new data indicator (NDI) indicating that the second data is a new data and is not retransmission of the first data, at a next transmission time of the first HARQ process;
• receive the result of reception of the first data indicating negative-acknowledgement (NACK);
• identify the first data based on the mapping information and the NACK;
• generate third data for retransmitting the first data;
• and
• transmit the third data based on a second HARQ process which is different from the first HARQ process,
• wherein the mapping information comprises an identifier (ID) of the first HARQ process, an identifier (ID) on the first data, a packet of the first data, and timing information regarding a time when a Protocol Data Unit (PDU) or Service Data Unit (SDU) is delivered through the first HARQ process ID.