5.37.10.3 Expedited Data Transfer with reflective QoS

Expedited Data Transfer with reflective QoS can be requested by AF to expedite the data transfer of larger payload for IP flow(s) of XR application. Expedited Data Transfer can be used for non-GBR SDF only.

To enable Expedited Data Transfer, the AF provides two media flows that contains the same SDF filter associated with different QoS requirements, one media flow is associated with Expedited Transfer Indication set to TRUE and the other one set to FALSE.

Expedited Data Transfer requires the PSA UPF to detect the "Expedited Transfer Indication" (contained in N6 metadata or in RTP Header Extension) in the downlink service data flow. To enable expedited transfer for encrypted traffic where the "Expedited Transfer Indication" is contained in N6 metadata, the AF provides information to enable transferring media related information over N6 (in clause 5.37.9). To enable expedited transfer for non-encrypted traffic where the "Expedited Transfer Indication" is contained in the RTP Header Extension, the AF may provide related protocol description information.

If the UE supports Reflective QoS, the PCF generates a PCC rule for each media flow with Expedited Transfer Indication based on the AF request. For the SDF with Expedited Transfer Indication set to TRUE, the Reflective QoS control is enabled in the PCC rule. And for the SDF with Expedited Transfer Indication set to FALSE, it is up to operator configuration to enable the Reflective QoS control or not in the PCC rule. Further details are described in clause 6.1.3.27 of TS 23.503 [45].

The SMF receives these two PCC rules and generates two PDRs including the Expedited Transfer Indication in the PDI. Expedited Transfer Indication is set to TRUE in the one PDR and to FALSE in the other. If UPF receives the PDRs with the Expedited Transfer Indication, it shall also detect "Expedited Transfer Indication" in the downlink packets (as described in clause 5.37.9 for encrypted traffic, or in RTP Header Extension/transport protocol header as defined in TS 26.522 [179]) to process the DL packets based on one of these two PDRs.