Method and apparatus for performing sidelink retransmission in NR V2X
A method by which a first device performs sidelink communication is provided. The method comprises the steps of: receiving, from a base station, a sidelink grant associated with a first retransmission resource and an initial transmission resource of a transport block; transmitting, to a second device, a PSCCH and a PSSCH associated with the PSCCH, on the basis of the initial transmission resource; determining a PSFCH resource for receiving a PSFCH from the second device, on the basis of the index of a slot and the index of a subchannel associated with the PSSCH; receiving, from the second device, the PSFCH on a first PSSCH, on the basis of the PSFCH resource; comparing a time interval between the PSFCH resource and the first retransmission resource with a minimum processing time required between the reception of the PSFCH and retransmission of the transport block.
1. A method for performing sidelink communication by a first device, the method comprising:
receiving, from a base station, a sidelink grant related to an initial transmission resource and a first retransmission resource of a transport block;
transmitting, to a second device, a Physical Sidelink Control Channel (PSCCH) and a Physical Sidelink Shared Channel (PSSCH) related to the PSCCH, based on the initial transmission resource;
determining a Physical Sidelink Feedback Channel (PSFCH) resource for receiving a PSFCH from the second device based on an index of a slot and an index of a subchannel related to the PSSCH;
receiving, from the second device, the PSFCH related to the PSSCH based on the PSFCH resource;
comparing a time interval between the PSFCH resource and the first retransmission resource with a minimum processing time required between reception of the PSFCH and retransmission of the transport block; and
performing sidelink communication with the second device based on comparison of the time interval and the minimum processing time,
wherein the transport block is a transport block for which a sidelink Hybrid Automatic Repeat Request (HARQ) feedback is enabled, and wherein, based on the time interval being less than the minimum processing time, the retransmission of the transport block on the first retransmission resource is dropped by the first device.
2. The method of claim 1 , wherein the transport block for which the sidelink HARQ feedback is enabled is a transport block to which a logical channel (LCH) for which the sidelink HARQ feedback is enabled is mapped.
3. The method of claim 1 , wherein, based on the time interval being less than the minimum processing time, the transport block for which the sidelink HARQ feedback is enabled is not transmitted to the second device, and the transport block for which the sidelink HARQ feedback is disabled is transmitted to the second device.
4. The method of claim 1 , wherein, based on a Channel State Information (CSI) reporting being enabled, a symbol set related the PSSCH in a sidelink slot does not include an AGC symbol and a symbol for transmission-reception switching.
5. The method of claim 4 , wherein the symbol set related to the PSSCH includes symbols other than the AGC symbol and the symbol for transmission-reception switching, from among sidelink symbols included in the sidelink slot.
6. The method of claim 5 , wherein a total number of symbols included in the symbol set related to the PSSCH is a value obtained by subtracting 2 from a total number of the sidelink symbols included in the sidelink slot.
7. The method of claim 4 , wherein the AGC symbol is a first symbol in time in the sidelink slot, and
wherein the symbol for transmission-reception switching is a last symbol in time in the sidelink slot.
8. The method of claim 4 , wherein the total number of symbols included in the symbol set related to the PSSCH is configured for a resource pool triggering the CSI reporting.
9. The method of claim 1 , further comprising:
transmitting, to the base station, a Physical Uplink Control Channel (PUCCH) related to the sidelink HARQ feedback for the sidelink grant based on the PSFCH; and
receiving, from the base station, downlink control information (DCI) including information on a second retransmission resource related to the sidelink grant;
wherein a cell for transmission of the PUCCH is determined based on a cell in which reception of the DCI is expected.
10. The method of claim 9 , wherein the information on the second retransmission resource is included in a dynamic grant scrambled with sidelink-configured scheduling-radio network temporary identifier (SL-CS-RNTI).
11. The method of claim 1 , wherein the sidelink grant is received based on an RRC signaling from the base station, and
wherein a type of the sidelink grant is sidelink configured grant (CG) type 1.
12. A first device configured to perform sidelink communication, the first device comprising:
at least one memory storing instructions;
at least one transceiver; and
at least one processor connecting the at least one memory and the at least one transceiver,
wherein the at least one processor is configured to:
control the at least one transceiver to receive, from a base station, a sidelink grant related to an initial transmission resource and a first retransmission resource of a transport block;
control the at least one transceiver to transmit, to a second device, a Physical Sidelink Control Channel (PSCCH) and a Physical Sidelink Shared Channel (PSSCH) related to the PSCCH, based on the initial transmission resource;
determine a Physical Sidelink Feedback Channel (PSFCH) resource for receiving a PSFCH from the second device based on an index of a slot and an index of a subchannel related to the PSSCH;
control the at least one transceiver to receive, from the second device, the PSFCH related to the PSSCH based on the PSFCH resource;
compare a time interval between the PSFCH resource and the first retransmission resource with a minimum processing time required between reception of the PSFCH and retransmission of the transport block; and
control the at least one transceiver to perform sidelink communication with the second device based on comparison of the time interval and the minimum processing time,
wherein the transport block is a transport block for which a sidelink Hybrid Automatic Repeat Request (HARQ) feedback is enabled, and wherein, based on the time interval being less than the minimum processing time, the retransmission of the transport block on the first retransmission resource is dropped by the first device.
13. An apparatus configured to control a first user equipment (UE), the apparatus comprising:
at least one processor; and
at least one computer memory operably connected to the at least one processor and storing instructions;
wherein, based on the at least one processor executing the instructions, the first UE is configured to:
receive, from a base station, a sidelink grant related to an initial transmission resource and a first retransmission resource of a transport block;
transmit, to a second device, a Physical Sidelink Control Channel (PSCCH) and a Physical Sidelink Shared Channel (PSSCH) related to the PSCCH, based on the initial transmission resource;
determine a Physical Sidelink Feedback Channel (PSFCH) resource for receiving a PSFCH from the second device based on an index of a slot and an index of a subchannel related to the PSSCH;
receive, from the second device, the PSFCH related to the PSSCH based on the PSFCH resource;
compare a time interval between the PSFCH resource and the first retransmission resource with a minimum processing time required between reception of the PSFCH and retransmission of the transport block; and
perform sidelink communication with the second device based on comparison of the time interval and the minimum processing time,
wherein the transport block is a transport block for which a sidelink Hybrid Automatic Repeat Request (HARQ) feedback is enabled, and wherein, based on the time interval being less than the minimum processing time, the retransmission of the transport block on the first retransmission resource is dropped by the first device.
14. The first device of claim 12 , wherein the transport block for which the sidelink HARQ feedback is enabled is a transport block to which a logical channel (LCH) for which the sidelink HARQ feedback is enabled is mapped.
15. The first device of claim 12 , wherein, based on the time interval being less than the minimum processing time, the transport block for which the sidelink HARQ feedback is enabled is not transmitted to the second device, and the transport block for which the sidelink HARQ feedback is disabled is transmitted to the second device.
16. The first device of claim 12 , wherein, based on a Channel State Information (CSI) reporting being enabled, a symbol set related the PSSCH in a sidelink slot does not include an AGC symbol and a symbol for transmission-reception switching.
17. The first device of claim 16 , wherein the symbol set related to the PSSCH includes symbols other than the AGC symbol and the symbol for transmission-reception switching, from among sidelink symbols included in the sidelink slot.
18. The first device of claim 17 , wherein a total number of symbols included in the symbol set related to the PSSCH is a value obtained by subtracting 2 from a total number of the sidelink symbols included in the sidelink slot.
19. The first device of claim 16 , wherein the AGC symbol is a first symbol in time in the sidelink slot, and
wherein the symbol for transmission-reception switching is a last symbol in time in the sidelink slot.
20. The first device of claim 16 , wherein the total number of symbols included in the symbol set related to the PSSCH is configured for a resource pool triggering the CSI reporting.