5 SDAP procedures

37.3243GPPEvolved Universal Terrestrial Radio Access (E-UTRA) and NRRelease 17Service Data Adaptation Protocol (SDAP) specificationTS

5.1 SDAP entity handling

5.1.1 SDAP entity establishment

When RRC (TS 38.331 [3]) requests an SDAP entity establishment, the UE shall:

– establish an SDAP entity;

– follow the procedures in clause 5.2.1 and 5.2.2.

When RRC (TS 38.331 [3]) requests establishment of an SDAP entity for unicast, groupcast or broadcast of NR sidelink communication, the UE shall:

– establish an SDAP entity;

– follow the procedures in clauses 5.2.3 and 5.2.4.

5.1.2 SDAP entity release

When RRC (TS 38.331 [3]) requests an SDAP entity release, the UE shall:

– release the SDAP entity.

When RRC (TS 38.331 [3]) requests release of an SDAP entity for unicast, groupcast or broadcast of NR sidelink communication, the UE shall:

– release the SDAP entity.

5.2 Data transfer

5.2.1 Uplink

At the reception of an SDAP SDU from upper layer for a QoS flow, the transmitting SDAP entity shall:

– if there is no stored QoS flow to DRB mapping rule for the QoS flow as specified in the clause 5.3:

– map the SDAP SDU to the default DRB;

– else:

– map the SDAP SDU to the DRB according to the stored QoS flow to DRB mapping rule;

– if the DRB to which the SDAP SDU is mapped is configured by RRC (TS 38.331 [3]) with the presence of SDAP header,

– construct the UL SDAP data PDU as specified in the clause 6.2.2.3;

– else:

– construct the UL SDAP data PDU as specified in the clause 6.2.2.1;

– submit the constructed UL SDAP data PDU to the lower layers.

NOTE 1: UE behaviour is not defined if there is neither a default DRB nor a stored QoS flow to DRB mapping rule for the QoS flow.

NOTE 2: Default DRB is always configured with UL SDAP header (TS 38.331 [3]).

5.2.2 Downlink

At the reception of an SDAP data PDU from lower layers for a QoS flow, the receiving SDAP entity shall:

– if this SDAP data PDU is received from an MRB:

– retrieve the SDAP SDU from the DL SDAP data PDU as specified in the clause 6.2.2.1.

– if the DRB from which this SDAP data PDU is received is configured by RRC (TS 38.331 [3]) with the presence of SDAP header:

– perform reflective QoS flow to DRB mapping as specified in the clause 5.3.2;

– perform RQI handling as specified in the clause 5.4;

– retrieve the SDAP SDU from the DL SDAP data PDU as specified in the clause 6.2.2.2.

– else:

– retrieve the SDAP SDU from the DL SDAP data PDU as specified in the clause 6.2.2.1;

– deliver the retrieved SDAP SDU to the upper layer.

5.2.3 SL transmission

At the reception of an SDAP SDU from upper layer for a PC5 QoS flow, the transmitting SDAP entity shall:

– if there is no stored PC5 QoS flow to SL-DRB mapping rule for the PC5 QoS flow as specified in the clause 5.5:

– map the SDAP SDU to the default SL-DRB;

– else:

– map the SDAP SDU to the SL-DRB according to the stored PC5 QoS flow to SL-DRB mapping rule;

– if the SL-DRB to which the SDAP SDU is mapped is configured by RRC (TS 38.331 [3]) with the presence of SDAP header:

– construct the SL SDAP data PDU as specified in the clause 6.2.2.4;

– else:

– construct the SL SDAP data PDU as specified in the clause 6.2.2.1;

– submit the constructed SL SDAP data PDU to the lower layers.

5.2.4 SL reception

At the reception of an SDAP data PDU from lower layers for a PC5 QoS flow, the receiving SDAP entity shall:

– if the SL-DRB from which this SDAP data PDU is received is configured by RRC (TS 38.331 [3]) with the presence of SDAP header:

– retrieve the SDAP SDU from the SL SDAP data PDU as specified in the clause 6.2.2.4;

– else:

– retrieve the SDAP SDU from the SL SDAP data PDU as specified in the clause 6.2.2.1;

– deliver the retrieved SDAP SDU to the upper layer.

5.3 QoS flow to DRB mapping

5.3.1 Configuration

When RRC (TS 38.331 [3]) configures an UL QoS flow to DRB mapping rule for a QoS flow, the SDAP entity shall:

– if the SDAP entity has already been established and there is no stored QoS flow to DRB mapping rule for the QoS flow and a default DRB is configured:

– construct an end-marker control PDU, as specified in the clause 6.2.3, for the QoS flow;

– map the end-marker control PDU to the default DRB;

– submit the end-marker control PDU to the lower layers.

– if the stored UL QoS flow to DRB mapping rule is different from the configured QoS flow to DRB mapping rule for the QoS flow and the DRB according to the stored QoS flow to DRB mapping rule is configured by RRC (TS 38.331 [3]) with the presence of UL SDAP header:

– construct an end-marker control PDU, as specified in the clause 6.2.3, for the QoS flow;

– map the end-marker control PDU to the DRB according to the stored QoS flow to DRB mapping rule;

– submit the end-marker control PDU to the lower layers.

– store the configured UL QoS flow to DRB mapping rule for the QoS flow.

When RRC (TS 38.331 [3]) releases an UL QoS flow to DRB mapping rule for a QoS flow, the SDAP entity shall:

– remove the UL QoS flow to DRB mapping rule for the QoS flow.

5.3.2 Reflective mapping

For each received DL SDAP data PDU with RDI set to 1, the SDAP entity shall:

– process the QFI field in the SDAP header and determine the QoS flow;

– if there is no stored QoS flow to DRB mapping rule for the QoS flow and a default DRB is configured:

– construct an end-marker control PDU, as specified in the clause 6.2.3, for the QoS flow;

– map the end-marker control PDU to the default DRB;

– submit the end-marker control PDU to the lower layers;

– if the stored QoS flow to DRB mapping rule for the QoS flow is different from the QoS flow to DRB mapping of the DL SDAP data PDU and the DRB according to the stored QoS flow to DRB mapping rule is configured by RRC (TS 38.331 [3]) with the presence of UL SDAP header:

– construct an end-marker control PDU, as specified in the clause 6.2.3, for the QoS flow;

– map the end-marker control PDU to the DRB according to the stored QoS flow to DRB mapping rule;

– submit the end-marker control PDU to the lower layers;

– store the QoS flow to DRB mapping of the DL SDAP data PDU as the QoS flow to DRB mapping rule for the UL.

5.3.3 DRB release

When RRC (TS 38.331 [3]) indicates that a DRB is released, the SDAP entity shall:

– remove all QoS flow to DRB mappings associated with the released DRB based on the clauses 5.3.1 and 5.3.2.

5.4 RQI handling

For each received DL SDAP data PDU with RQI set to 1, the SDAP entity shall:

– inform the NAS layer of the RQI and QFI.

5.5 PC5 QoS flow to SL-DRB mapping

5.5.1 Configuration

When RRC (TS 38.331 [3]) configures a PC5 QoS flow to SL-DRB mapping rule for a PC5 QoS flow, the SDAP entity shall:

– for unicast of NR sidelink communication, if the SDAP entity has already been established and there is no stored SL-DRB mapping rule for the PC5 QoS flow and a default SL-DRB is configured:

– construct an end-marker control PDU, as specified in the clause 6.2.3, for the PC5 QoS flow;

– map the end-marker control PDU to the default SL-DRB;

– submit the end-marker control PDU to the lower layers;

– for unicast of NR sidelink communication, if the stored PC5 QoS flow to SL-DRB mapping rule is different from the configured PC5 QoS flow to SL-DRB mapping rule for the PC5 QoS flow and the SL-DRB according to the stored PC5 QoS flow to SL-DRB mapping rule is configured by RRC (TS 38.331 [3]) with the presence of SL SDAP header:

– construct an end-marker control PDU, as specified in the clause 6.2.3, for the PC5 QoS flow;

– map the end-marker control PDU to the SL-DRB according to the stored PC5 QoS flow to SL-DRB mapping rule;

– submit the end-marker control PDU to the lower layers;

– store the configured PC5 QoS flow to SL-DRB mapping rule for the PC5 QoS flow.

When RRC (TS 38.331 [3]) releases a PC5 QoS flow to SL-DRB mapping rule for a PC5 QoS flow, the SDAP entity shall:

– remove the PC5 QoS flow to SL-DRB mapping rule for the PC5 QoS flow.

5.5.2 SL-DRB release

When RRC (TS 38.331 [3]) indicates that an SL-DRB is released, the SDAP entity shall:

– remove all PC5 QoS flow to SL-DRB mappings associated with the released SL-DRB based on the clause 5.5.1.