Method and apparatus for performing retransmission in NR V2X
Proposed are a method for performing retransmission by a first device ( 100 ) and an apparatus for supporting the same. The method may include: performing transmission of first information to a second device ( 200 ); and performing feedback-based retransmission or blind retransmission of the first information based on a delay deadline for the first information.
1. A method for performing wireless communication by a first device, the method comprising:
obtaining medium access control (MAC) packet data unit (PDU) for which HARQ (hybrid automatic repeat request) feedback is enabled;
performing transmission of the MAC PDU to a second device; and
determining a remaining packet delay budget (PDB) of the MAC PDU,
wherein the remaining PDB of the MAC PDU is a first difference value between a first time when the first device obtains the MAC PDU and a second time of a delay deadline for the MAC PDU,
configuring the MAC PDU for which the HARQ feedback is disabled, based on the remaining PDB of the MAC PDU being less than or equal to a threshold;
performing retransmission of the MAC PDU based on the remaining PDB of the MAC PDU being less than or equal to the threshold,
wherein the retransmission of the MAC PDU is a blind retransmission,
wherein the retransmission of the MAC PDU includes a HARQ retransmission of the MAC PDU, and
wherein the HARQ retransmission of the MAC PDU is performed by a medium access control (MAC) layer of the first device.
2. The method of claim 1 , wherein the MAC PDU is sidelink information, uplink information, or downlink information.
3. The method of claim 1 , further comprising:
determining a number of the blind retransmissions of the MAC PDU based on at least one of a reliability requirement for the MAC PDU or a congestion level.
4. The method of claim 3 , wherein the number of the blind retransmissions of the MAC PDU increases as the reliability requirement increases or the congestion level increases.
5. The method of claim 3 , wherein the blind retransmissions are performed only when the MAC PDU has a high QoS requirement or a high priority.
6. The method of claim 1 , further comprising:
transmitting control information comprising scheduling information on the transmission and scheduling information on the retransmission to the second device.
7. A first device for performing wireless communication, the first device comprising:
at least one memory;
at least one transceiver; and
at least one processor to couple the at least one memory and the at least one transceiver,
wherein the processor is configured to control the transceiver to:
obtain medium access control (MAC) packet data unit (PDU) for which HARQ (hybrid automatic repeat request) feedback is enabled;
perform transmission of the MAC PDU to the second device,
determine a remaining packet data budget (PDB) of the MAC PDU,
wherein the remaining PDB of the MAC PDU is a first difference value between a first time when the first device obtains the MAC PDU and a second time of a delay deadline for the MAC PDU,
configure the MAC PDU for which the HARQ feedback is disabled, based on the remaining PDB of the MAC PDU being less than or equal to a threshold, and
perform retransmission of the MAC PDU based on the remaining PDB of the MAC PDU being less than or equal to a threshold,
wherein the retransmission of the MAC PDU is a blind retransmission,
wherein the retransmission of the MAC PDU includes HARQ retransmission of the MAC PDU, and
wherein the HARQ retransmission of the MAC PDU is performed by a medium access control (MAC) layer of the first device.
8. The first device of claim 7 , wherein the MAC PDU is sidelink information, uplink information, or downlink information.