Inter-UE coordination signaling for sidelink communication
An apparatus and system for inter-UE coordination feedback for sidelink communications are described. In particular, inter-UE coordination feedback signaling for reliable sidelink communication including transmitter-based resource allocation and signaling of conflicts, prioritization of the inter-UE coordination feedback, and timing of the inter-UE coordination feedback are described. Sidelink hybrid acknowledgment request (HARQ) acknowledgment/negative acknowledgment (ACK/NACK) or NACK only signaling is prioritized over a half-duplex (HD) or co-channel collision (CC) feedback indication, and uplink transmissions are prioritized over sidelink transmissions. In response to detection of a conflict, the inter-UE coordination feedback is transmitted relative to the slot where the HD or CC event occurs or relative to the slot where reservation of the resources for the sidelink transmissions.
1 . An apparatus for user equipment (UE) configured for sidelink inter-UE coordination in a fifth-generation new radio (5G NR) network, the apparatus comprising: processing circuitry and memory, the processing circuitry configured to:
decode a physical sidelink feedback channel (PSFCH) received from a peer UE, the PSFCH comprising inter-UE coordination information;
decode a sidelink control information (SCI) scheduling a physical sidelink shared channel (PSSCH) reception from the peer UE;
select, based on the inter-UE coordination information, resources for transmitting Hybrid Automatic Repeat request (HARQ-ACK) feedback in response to the PSSCH reception; and
encode a PSFCH to include the HARQ-ACK feedback for transmission on the resources selected for transmitting the HARQ-ACK feedback,
wherein to select the resources for transmitting the HARQ-ACK feedback, the processing circuitry is configured to exclude resources with potential conflicts from a resource set indicated by the inter-UE coordination information,
wherein the processing circuitry is further configured to:
determine, based on the SCI, a set of resources that are reserved for the PSSCH reception;
determine conflict information for the set of resources that are reserved for the PSSCH reception; and
encode a PSFCH for transmission to the peer UE, the PSFCH encoded to provide the conflict information to the peer UE.
2 . The apparatus of claim 1 , wherein the processing circuitry is further configured to re-select resources for the PSSCH reception based on the inter-UE coordination information.
3 . The apparatus of claim 2 , wherein the inter-UE coordination information includes reference signal received power (RSRP) thresholds for use in determining reserved resources of other UEs.
4 . The apparatus of claim 3 , wherein to exclude resources with potential conflicts, the processing circuitry is configured to:
apply a first of the RSRP thresholds to the PSSCH reception received from the peer UE; and
apply a second of the RSRP thresholds to transmissions received from a third UE.
5 . The apparatus of claim 4 , wherein the inter-UE coordination information further includes priority information for each of the RSRP thresholds, and
wherein the processing circuitry is configured determine which of the RSRP thresholds to apply based on a priority indicated in the SCI.
6 . The apparatus of claim 4 , wherein the UE is further configured to exclude single-slot resources belonging to slots where the UE does not expect to perform sidelink reception of a transport block due to half-duplex operation.
7 . The apparatus of claim 4 , wherein for the sidelink inter-UE coordination, the UE is configured in Mode 2 in which sidelink transmission resources are determined by the UE rather than the network.
8 . The apparatus of claim 4 , wherein when the RSRP thresholds include:
a first RSRP threshold for use in determining reserved resources of other UEs; and
a second RSRP threshold for use in determining priorities for resource conflicts.
9 . The apparatus of claim 4 , wherein the processing circuitry is to configure the UE to perform sensing to determine RSRP levels for comparison to the RSRP thresholds.
10 . A non-transitory computer-readable storage medium that stores instructions for execution by processing circuitry of a user equipment (UE) configured for sidelink inter-UE coordination in a fifth-generation new radio (5G NR) network, the processing circuitry configured to:
decode a physical sidelink feedback channel (PSFCH) received from a peer UE, the PSFCH comprising inter-UE coordination information;
decode a sidelink control information (SCI) scheduling a physical sidelink shared channel (PSSCH) reception from the peer UE;
select, based on the inter-UE coordination information, resources for transmitting Hybrid Automatic Repeat request (HARQ-ACK) feedback in response to the PSSCH reception; and
encode a PSFCH to include the HARQ-ACK feedback for transmission on the resources selected for transmitting the HARQ-ACK feedback,
wherein to select the resources for transmitting the HARQ-ACK feedback, the processing circuitry is configured to exclude resources with potential conflicts from a resource set indicated by the inter-UE coordination information,
wherein the processing circuitry is further configured to:
determine, based on the SCI, a set of resources that are reserved for the PSSCH reception;
determine conflict information for the set of resources that are reserved for the PSSCH reception; and
encode a PSFCH for transmission to the peer UE, the PSFCH encoded to provide the conflict information to the peer UE.
11 . The non-transitory computer-readable storage medium of claim 10 , wherein the processing circuitry is further configured to re-select resources for the PSSCH reception based on the inter-UE coordination information.
12 . The non-transitory computer-readable storage medium of claim 11 , wherein the inter-UE coordination information includes reference signal received power (RSRP) thresholds for use in determining reserved resources of other UEs.
13 . The non-transitory computer-readable storage medium of claim 12 , wherein to exclude resources with potential conflicts, the processing circuitry is configured to:
apply a first of the RSRP thresholds to the PSSCH reception received from the peer UE; and
apply a second of the RSRP thresholds to transmissions received from a third UE.
14 . The non-transitory computer-readable storage medium of claim 13 , wherein the inter-UE coordination information further includes priority information for each of the RSRP thresholds, and
wherein the processing circuitry is configured determine which of the RSRP thresholds to apply based on a priority indicated in the SCI.
15 . The non-transitory computer-readable storage medium of claim 13 , wherein the UE is further configured to exclude single-slot resources belonging to slots where the UE does not expect to perform sidelink reception of a transport block due to half-duplex operation.
16 . An apparatus for user equipment (UE) configured for sidelink inter-UE coordination in a fifth-generation new radio (5G NR) network, the apparatus comprising: processing circuitry and memory, the processing circuitry configured to:
encode a physical sidelink feedback channel (PSFCH) for transmission to a peer UE, the PSFCH comprising inter-UE coordination information;
encode a sidelink control information (SCI) scheduling a physical sidelink shared channel (PSSCH) transmission to the peer UE;
decode a PSFCH received from the peer UE, the PSFCH received on resources selected by the peer UE for transmitting Hybrid Automatic Repeat request (HARQ-ACK) feedback in response to the PSSCH transmission, wherein resources with potential conflicts are excluded by the peer UE from a resource set indicated by the inter-UE coordination information,
wherein the processing circuitry is further configured to decode a PSFCH received from the peer UE, the PSFCH indicating conflict information for the set of resources that are reserved for the PSSCH.
17 . The apparatus of claim 16 , wherein the inter-UE coordination information includes reference signal received power (RSRP) thresholds for use in determining, by the peer UE, reserved resources of other UEs.