3GPP 38.300 v19.3.0 — the document's own text
16.9.9.2 Channel Access Priority Classes for Sidelink (SL-CAPC)
The SL-CAPC of SL radio bearers and SL MAC CEs are either fixed or (pre)configurable as follows:
- Fixed to the highest priority for all SL-SRBs and SL MAC CEs
- (Pre)configurable per DRB for all SL-DRBs
When choosing the SL-CAPC for a SL-DRB the network takes into account the PQIs of all QoS flows mapped to that SL DRB. Table 16.9.9-1 below shows which SL-CAPC should be used for which standardized PQI(s), i.e., which SL-CAPC to use for a given QoS flow. For a UE in RRC_IDLE/RRC_INACTIVE or OOC, the UE uses the SL-CAPC configured in SIB/Pre-configuration when the QoS flow can be mapped to a non-default SLRB, or when the default SLRB is used for the QoS flow and the SL-CAPC of the default SLRB is configured.
When the default SLRB is used for the QoS flow and the SL-CAPC of the default SLRB is not configured:
- if the QoS flow is associated with standardized PQI, the UE derives SL-CAPC for the flow directly from the table below
- if the QoS flow is associated with non-standardized PQI, the UE may select the SL-CAPC of the standardized PQI having the closest PDB.
The UE then selects the lowest SL-CAPC priority level (highest SL-CAPC value) among the QoS flows to determine the SL-CAPC for the default SLRB.
Table 16.9.9-1: Mapping between Channel Access Priority Classes for SL-U and PQI
| SL-CAPC | PQI |
|---|---|
| 1 | 21, 22, 23, 24, 26, 33, 55, 56, 57, 58, 60, 71, 90, 91, 92, 93 |
| 2 | 25, 70 |
| 3 | 32, 34, 59, 61 |
| 4 | - |
| NOTE: lower SL-CAPC value means higher priority- |
When performing Type 1 LBT for the transmission of a sidelink TB, the SL UE shall select the SL-CAPC as follows:
- If only SL MAC CE(s) are included in the SL TB, the highest priority SL-CAPC is used; or
- If SCCH SDU(s) are included in the SL TB, the highest priority SL-CAPC is used; or
- The lowest priority SL-CAPC of the SL logical channel(s) with MAC SDU(s) multiplexed in the TB is used otherwise.
The highest priority SL-CAPC is used for SBCCH SDU transmissions and PSFCH transmissions.