5.9 Procedure for resource management of background data transfer

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

This clause describes the procedure for resource management of background data transfer to a set of UEs, i.e. an SCS/AS requesting a time window and related conditions from the SCEF via the Nt interface.

The UEs targeted for background data transfer may be served by a single PCRF or may be spread across multiple PCRFs serving the same or different geographic areas. The operator shall ensure that any of the PCRFs in the network is able to make the decision about transfer policy for background data transfer for non-roaming UEs.

The transfer policy will be stored in the SPR together with a Reference ID. This ensures that the transfer policy is available to every PCRF responsible for a UE which is subject to this background data transfer in the future. In addition, other (or the same) PCRF can take this transfer policy into account during subsequent decisions about transfer policies for background data related to other SCS/AS.

At a later point in time, when the SCS/AS (acting as an AF), contacts the PCRF for individual UEs, e.g. to request sponsored connectivity for background data transfer, the SCS/AS needs to also provide the Reference ID together with the SCS/AS session information via the Rx interface. Alternatively, the SCS/AS activates the selected transfer policy via the SCEF, for each UE in the group, by using the "Set the chargeable party at session set-up" or "Change the chargeable party during the session" procedure from clauses 5.12.1 and 5.12.2 to provide the Reference ID to the same or different PCRF. The Reference ID enables the PCRF to correlate the SCS/AS request (that is related to the UE) with the transfer policy retrieved from the SPR (that is related to the SCS/AS). The PCRF finally triggers PCC procedures according to TS 23.203 [27] to provide the respective policing and charging information to the PCEF.

Figure 5.9-1: Resource management for background data transfer

1. A 3rd party SCS/AS sends a Background data transfer request (SCS/AS Identifier, Volume per UE, Number of UEs, Desired time window) message to the SCEF. The Volume per UE describes the volume of data the SCS/AS expects to be transferred per UE. Number of UEs describes the expected amount of UEs participating in the data transfer. Desired time window describes the time interval during which the SCS/AS wants to realize the data transfer. Optionally, the SCS/AS can provide a geographic area information.

NOTE 1: The SCS/AS does not provide any information about the identity of the UEs in this request.

2. The SCEF authorizes the SCS/AS request.

NOTE 2: The SCEF notifies the SCS/AS at this point if the authorization fails.

3. The SCEF selects any of the available PCRFs and triggers the Negotiation for future background data transfer procedure with the PCRF. The SCEF forwards the parameters provided by the SCS/AS. The PCRF responds to the SCEF with the possible transfer policies and a Reference ID. Refer to clause 7.11.1 of TS 23.203 [27].

4. The SCEF forwards the Reference ID and the transfer policies to the 3rd party SCS/AS by sending a Background data transfer response (Reference ID, Possible transfer policies) message. The SCS/AS stores the Reference ID for the future interaction with the PCRF.

5. If more than one transfer policy was received, the 3rd party SCS/AS shall select one of them and send another Background data transfer request (SCS/AS Identifier, Selected transfer policy) message to inform the SCEF and PCRF about the selected transfer policy.

NOTE 3: If there is only one transfer policy offered, the SCS/AS is not required to confirm.

6. The SCEF confirms the transfer policy selection to the 3rd party SCS/AS by sending a Background data transfer response (Cause) message.

7. The SCEF continues the Negotiation for future background data transfer procedure with the PCRF. The PCRF stores the Reference ID and the new transfer policy in the SPR. Refer to clause 7.11.1 of TS 23.203 [27].

8. The SCS/AS (acting as an AF) contacts the same or a different PCRF for each individual UE (via the Rx interface), the SCS/AS shall provide the Reference ID. Alternatively, the SCS/AS activates the selected transfer policy via the SCEF, for each UE in the group, by using the "Set the chargeable party at session set-up" or "Change the chargeable party during the session" procedure from clauses 5.12.1 and 5.12.2 to provide the Reference ID to the same or different PCRF. The PCRF correlates the SCS/AS or SCEF request with the transfer policy retrieved from the SPR via the Reference ID. The PCRF finally triggers PCC procedures according to TS 23.203 [27] to provide the respective policing and charging information to the PCEF for the background data transfer of this UE.

NOTE 4: The SCS/AS will typically request sponsored connectivity for the background data transfer to individual UEs.

NOTE 5: The SCS/AS can contact the PCRF directly or interact with the PCRF via the SCEF.