Sidelink HARQ
A user equipment (UE) communicates with a further UE via a sidelink and communicates with a cell of a network via an uplink. The UE receives a hybrid automatic repeat request (HARQ) acknowledgement (ACK) timing parameter from the network, generates a sidelink HARQ-ACK codebook based on a signaling exchange with the further UE, wherein the sidelink HARQ-ACK codebook is constructed in decreasing order of one or more physical sidelink shared channel (PSSCH) transmission slots associated with a configured physical sidelink feedback channel (PSFCH) occasion, and transmits an indication of the sidelink HARQ-ACK codebook to the cell of the network.
1. A user equipment (UE), comprising:
a transceiver configured to communicate with a further UE via a sidelink and to communicate with a cell of a network via an uplink; and
a processor communicatively coupled to the transceiver and configured to perform operations comprising:
receiving a physical sidelink feedback channel (PSFCH)-to-hybrid automatic repeat request (HARQ) feedback timing indicator from the network via a Downlink Control Information (DCI) format 3_0;
generating a sidelink HARQ-ACK codebook with one or more physical sidelink shared channel (PSSCH) transmission slots associated with a configured physical sidelink feedback channel (PSFCH) occasion based on the PSFCH-to-HARQ feedback timing indicator of the DCI format 3_0; and
transmitting an indication of the sidelink HARQ-ACK codebook to the cell of the network.
2. The UE of claim 1 , wherein a HARQ feedback is transmitted from the further UE on the PSFCH.
3. The UE of claim 1 , wherein the operations further comprise:
receiving an indication from the cell as to whether a physical uplink control channel (PUCCH) resource is allocated to the UE to send HARQ feedback from the sidelink to the cell; and
when the PUCCH resource is allocated, transmitting the HARQ feedback to the to the cell on the PUCCH resource.
4. The UE of claim 1 , wherein the PSFCH-to-HARQ feedback timing indicator represents a slot duration between a last PSFCH occasion and a PUCCH transmission.
5. The UE of claim 1 , wherein the sidelink HARQ-ACK codebook is one of a type 1 or a type 2 codebook.
6. A processor of a user equipment (UE) configured to perform operations comprising:
receiving a physical sidelink feedback channel (PSFCH)-to-hybrid automatic repeat request (HARQ) feedback timing indicator from a network via a Downlink Control Information (DCI) format 3_0;
generating a sidelink HARQ-ACK codebook with one or more physical sidelink shared channel (PSSCH) transmission slots associated with a configured physical sidelink feedback channel (PSFCH) occasion based on the PSFCH-to-HARQ feedback timing indicator of the DCI format 3_0; and
transmitting an indication of the sidelink HARQ-ACK codebook to a cell of the network.
7. The processor of claim 6 , wherein a HARQ feedback is transmitted from the further UE on the PSFCH.
8. The processor of claim 6 , wherein the operations further comprise:
receiving an indication from the cell as to whether a physical uplink control channel (PUCCH) resource is allocated to the UE to send HARQ feedback from the sidelink to the cell; and
when the PUCCH resource is allocated, transmitting the HARQ feedback to the to the cell on the PUCCH resource.
9. The processor of claim 6 , wherein the PSFCH-to-HARQ feedback timing indicator represents a slot duration between a last PSFCH occasion and a PUCCH transmission.
10. The processor of claim 6 , wherein the sidelink HARQ-ACK codebook is one of a type 1 or a type 2 codebook.
11. A user equipment (UE), comprising:
a transceiver configured to communicate with a further UE via a sidelink; and
a processor communicatively coupled to the transceiver and configured to perform operations comprising:
determining candidate physical sidelink feedback channel (PSFCH) resources, wherein the candidate PSFCH resources correspond to a resource pool and wherein determining the candidate PSFCH resources is based on a starting subchannel used for physical sidelink shared channel (PSSCH); and
transmitting hybrid automatic repeat request (HARQ) feedback on one or more of the PSFCH resources.
12. The UE of claim 11 , wherein the candidate PSFCH resources further correspond to unicast or groupcast option 1.
13. The UE of claim 11 , wherein the candidate PSFCH resources further correspond to groupcast option 2 and wherein determining the candidate PSFCH resources is based on subchannels and a slot used for PSSCH reception.
14. The UE of claim 11 , wherein resource pool configuration information indicates determining the candidate PSFCH resources is based on one of a starting subchannel and slot used for PSSCH reception or subchannels and slots used for PSSCH reception.