Section: 16.9.9.2 Channel Access Priority Classes for Sidelink (SL-CAPC)
Content: 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 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.