Power saving enhancement for sidelink

1 . A method of sidelink resource selection, comprising:

determining, by a first user equipment (UE), based on a first sidelink resource allocation process according to a mode-2 sidelink operation, first radio resources for one or more first sidelink transport blocks;

transmitting, by the first UE to a second UE, the one or more first sidelink transport blocks based on the first radio resources;

receiving, by the first UE, first hybrid automatic repeat request (HARQ) feedback for the one or more first sidelink transport blocks;

determining, by the first UE, whether to switch from the first sidelink resource allocation process according to the mode-2 sidelink operation to a second sidelink resource allocation process according to the mode-2 sidelink operation based on the HARQ feedback;

responsive to a determination to switch to the second sidelink resource allocation process according to the mode-2 sidelink operation, determining, by the first UE, second radio resources for one or more second sidelink transport blocks based on the second sidelink resource allocation process according to the mode-2 sidelink operation; and

transmitting, by the first UE, the one or more second sidelink transport blocks based on the second radio resources,

wherein the HARQ feedback is based on a first number of negative acknowledgements (NACKs) and a second number of positive acknowledgements (ACKs), wherein determining whether to switch from the first sidelink resource allocation process to the second sidelink resource allocation process is based on whether a proportion of the first number of NACKs and the second number of ACKs is greater than first threshold, and

wherein the proportion corresponds to a ratio of the first number of NACKs to a sum of the first number of NACKs and the second number of ACKs.

2 . The method of claim 1 , further comprising receiving a configuration parameter, wherein the configuration parameter received defines the first threshold.

3 . The method of claim 1 , wherein receiving the HARQ feedback includes receiving the HARQ feedback within a first time window.

4 . The method of claim 3 further comprising receiving a configuration parameter, wherein the configuration parameter received defines a duration of the first time window.

5 . The method of claim 1 , wherein the first sidelink resource allocation process corresponds to at least one of a full sensing process, a partial sensing process and a random resource selection process.

6 . The method of claim 1 , wherein the second sidelink resource allocation process is one of a partial sensing resource allocation process and a random resource selection resource allocation process.

7 . The method of claim 1 , wherein:

the first sidelink resource allocation process is a random resource selection resource allocation process; and

the second sidelink resource allocation process is a partial sensing resource allocation process.

8 . The method of claim 7 , wherein a partial sensing window size of the partial sensing resource allocation process corresponds to a first size.

9 . The method of claim 8 further comprising the first UE receiving a configuration parameter defining the first size.

10 . The method of claim 7 further comprising receiving, by the first UE, second HARQ feedback, related to the transmitting of the one or more second sidelink transport blocks.

11 . The method of claim 10 , wherein receiving, by the first UE, the second HARQ feedback includes receiving the second HARQ feedback within a second time window.

12 . The method of claim 11 further comprising receiving a configuration parameter, wherein the configuration parameter received defines a duration of the second time window.

13 . The method of claim 10 further comprising determining to switch to the random resource selection resource allocation process based on the second HARQ feedback.

14 . The method of claim 13 , wherein the second HARQ feedback is based on a third number of NACKs and a fourth number of ACKs, the method further comprising determining, by the first UE, to switch to the random resource selection resource allocation process based on whether a ratio of the third number of NACKs to a sum of the third number of NACKS and the fourth number of ACKs is less than a second threshold.

15 . The method of claim 14 further comprising receiving a configuration parameter, wherein the configuration parameter received defines the second threshold.

16 . The method of claim 10 , further comprising determining, by the first UE, to increase a partial sensing window size based on the second HARQ feedback.

17 . A method of sidelink resource selection, comprising:

determining, by a first user equipment (UE), based on a partial sensing resource allocation process associated with a first window size, first radio resources for one or more first sidelink transport blocks;

transmitting, by the first UE to a second UE, the one or more first sidelink transport blocks based on the first radio resources;

receiving, by the first UE, hybrid automatic repeat request (HARQ) feedback for the one or more first sidelink transport blocks, wherein the HARQ feedback is based on a first number of negative acknowledgements (NACKs) and a second number of positive acknowledgements (ACKs);

identifying, by the first UE, a NACK ratio of the first number of NACKs to a sum of the first number of NACKs and the second number of ACKs;

determining, by the first UE, based on the partial sensing resource allocation process associated with a second window size, second radio resources for one or more second sidelink transport blocks, wherein the second window size is larger than, smaller than or equal to the first window size based on comparing the NACK ratio with one or more thresholds; and

transmitting, by the first UE, the one or more second sidelink transport blocks based on the second radio resources.

18 . A method of sidelink resource selection, comprising:

receiving, by a second user equipment (UE) from a first UE, one or more first sidelink transport blocks based on first radio resources determined based on a first sidelink resource allocation process according to a mode-2 sidelink operation;

transmitting, by the second UE to the first UE, first hybrid automatic repeat request (HARQ) feedback for the one or more first sidelink transport blocks; and

responsive to a determination to switch from the first sidelink resource allocation process according to the mode-2 sidelink operation to a second sidelink resource allocation process according to the mode-2 sidelink operation based on the HARQ feedback, receiving, from the first UE, one or more second sidelink transport blocks based on a second radio resources determined based on the second sidelink resource allocation process according to the mode-2 sidelink operation,

wherein the HARQ feedback is based on a first number of negative acknowledgements (NACKs) and a second number of positive acknowledgements (ACKs), wherein determining whether to switch from the first sidelink resource allocation process to the second sidelink resource allocation process is based on whether a proportion of the first number of NACKs and the second number of ACKs is greater than first threshold, and

wherein the proportion corresponds to a ratio of the first number of NACKs to a sum of the first number of NACKs and the second number of ACKs.