3GPP 38.300 v19.3.0 — the document's own text
5.6.2 Channel Access Priority Classes
Taught in 2. The six working groups and the line between them (TSG RAN — the group that specifies the radio, overview), 2. The six groups, and what each one worries about (TSG RAN — the group that specifies the radio, quick start).
The Channel Access Priority Classes (CAPC) of radio bearers and MAC CEs are either fixed or configurable for operation in FR1:
- Fixed to the lowest priority for the padding BSR and recommended bit rate MAC CEs;
- Fixed to the highest priority for SRB0, SRB1, SRB3 and other MAC CEs;
- Configured by the gNB for SRB2 and DRB.
When choosing the CAPC of a DRB, the gNB takes into account the 5QIs of all the QoS flows multiplexed in that DRB while considering fairness between different traffic types and transmissions. Table 5.6.2-1 below shows which CAPC should be used for which standardized 5QIs i.e. which CAPC to use for a given QoS flow.
NOTE: A QoS flow corresponding to a non-standardized 5QI (i.e. operator specific 5QI) should use the CAPC of the standardized 5QI which best matches the QoS characteristics of the non-standardized 5QI.
Table 5.6.2-1: Mapping between Channel Access Priority Classes and 5QI
| CAPC | 5QI |
|---|---|
| 1 | 1, 3, 5, 65, 66, 67, 69, 70, 79, 80, 82, 83, 84, 85 |
| 2 | 2, 7, 71 |
| 3 | 4, 6, 8, 9, 72, 73, 74, 76 |
| 4 | - |
| NOTE: lower CAPC value means higher priority- |
When performing Type 1 LBT for the transmission of an uplink TB (see TS 37.213 [37], clause 4.2.1.1) and when the CAPC is not indicated in the DCI, the UE shall select the CAPC as follows:
- If only MAC CE(s) are included in the TB, the highest priority CAPC of those MAC CE(s) is used; or
- If CCCH SDU(s) are included in the TB, the highest priority CAPC is used; or
- If DCCH SDU(s) are included in the TB, the highest priority CAPC of the DCCH(s) is used; or
- The lowest priority CAPC of the logical channel(s) with MAC SDU multiplexed in the TB is used otherwise.