5.11 Setting up an AS session with required QoS procedure

23.6823GPPArchitecture enhancements to facilitate communications with packet data networks and applicationsRelease 17TS

This clause describes the signalling flow for setting up a 3rd party AS session with a specific QoS.

Figure 5.11-1: Setting up an AS session with required QoS

1. When setting up the connection between SCS/AS and the UE with required QoS for the service, the SCS/AS sends an On-demand QoS request message (UE IP address, SCS/AS Identifier, Description of the application flows or External Application Identifier, QoS reference) to the SCEF. Optionally, a period of time or a traffic volume for the requested QoS can be included in the SCS/AS request. The SCEF assigns a TLTRI to the On-demand QoS request.

2. The SCEF authorizes the SCS/AS request and may apply policies to control the overall amount of pre-defined QoS authorized for the SCS/AS. If the authorisation is not granted, steps 3 and 4 are skipped and the SCEF replies to the SCS/AS with a Result value indicating that the authorisation failed.

3. The SCEF maps the UE IP address, the SCS/AS Identifier, the Description of the application flows and the QoS reference to existing Rx parameters (including the optionally received period of time or traffic volume which is mapped to sponsored data connectivity information). The SCEF acts as an AF defined in TS 23.203 [27].

NOTE: Before the QoS reference is mapped to Rx parameters, the SCEF can perform a mapping from the name space of the 3rd party SCS/AS to the name space of the operator.

4. The SCEF interacts with the PCRF via the Rx interface and triggers a PCRF initiated IP-CAN Session Modification as described in clause 7.4.2 of TS 23.203 [27]. The SCEF shall request to be notified about the transmission resource status.

The PCRF derives the required QoS based on the information provided by the SCEF and determines whether this QoS is allowed (according to the PCRF configuration for this 3rd party SCS/AS), and notifies the result to the SCEF.

The PCRF notifies the SCEF whether the transmission resources corresponding to the QoS request are established or not.

5. The SCEF sends an On-demand QoS response message (TLTRI, Result) to the SCS/AS. Result indicates whether the QoS request is granted or not.

6. The PCRF may notify the SCEF about bearer level events for the Rx session (e.g. transmission resources are released/lost) with a PCEF initiated IP-CAN Session Modification as described in clause 7.4.1 of TS 23.203 [27].

7. If the SCEF gets informed by the PCRF about bearer level events for the Rx session (e.g. transmission resources are released/lost) the SCEF sends a Status information message (SCS/AS Identifier, TLTRI, Status) to the SCS/AS. The status indicates the bearer level event received from the PCRF.