HARQ Feedback Timing Redefinition for Ultra-Low Latency

The HARQ feedback timing is segmented into multiple distinct timing locations (first timing location and second timing location). The first timing location is used for rapid NACK feedback with shorter delay, while the second timing location handles ACK feedback or NACK feedback when fast decoding is not available. This segmentation allows the system to achieve ultra-low delay for error cases without completely redesigning the HARQ feedback structure.

The terminal performs fast decoding of the received data block and prepares a NACK feedback in advance at the first timing location. If the fast decoding indicates an error, the NACK is immediately fed back at the first timing location, achieving rapid retransmission. This preliminary action of fast decoding and advance NACK preparation enables the system to reduce retransmission delay without waiting for the standard processing time.

The feedback timing is divided into separate locations: the first timing location is dedicated for rapid NACK feedback, while the second timing location is used for ACK feedback or NACK feedback when fast decoding is unavailable. This segmentation enables NACK to be fed back faster than ACK by assigning them to different timing locations with different delays.

Different timing locations are assigned different functions based on the feedback type and urgency. The first timing location provides ultra-low delay for NACK feedback when errors are detected through fast decoding, while the second timing location handles normal ACK/NACK feedback. This local differentiation of timing quality allows optimized feedback speed for error cases without affecting the overall system structure.