Method for harq feedback in wireless communication system and apparatus therefor

A user equipment (UE) for performing fast retransmission in a wireless communication system, the UE comprising:

• a receiver and a transmitter;
• and
• a processor configured to control the receiver and the transmitter,
• wherein the processor:
• receives downlink (DL) data or transmits uplink (UL) data, and
• performs a hybrid automatic repeat request (HARQ) behavior including retransmission for the DL data or the UL data without HARQ-acknowledgement (ACK) transmission and reception or without retransmission scheduling,
• wherein the HARQ behavior is configured as one of the following methods in which
• whether to perform the retransmission is configured per traffic usage or service type of the DL data or the UL data,
• whether to perform the retransmission is configured per time or frequency resource set in which the DL data or the UL data is transmitted,
• whether to perform retransmission is configured per DL control information format for scheduling the DL data or the UL data and/or search space of a DL control channel,
• whether to perform the retransmission is configured per modulation and coding scheme (MCS) and/or quality of service (Qos) class set of the DL data or the UL data, and
• whether to perform the retransmission is configured according to a target block error rate (BLER) of the DL data or the UL data.