Section: 4.16.7 Negotiations for future background data transfer 4.16.7.1 General
Content: The procedure for future background data transfer as specified in clause 4.16.7.2 enables the negotiation between the NEF and the H-PCF about the transfer policies for the future background data transfer (as described in clause 6.1.2.4 of TS 23.503[ Policy and charging control framework for the 5G System (5GS); Stage 2 ]  [20]). The transfer policies consist of a desired time window for the background data transfer, a reference to a charging rate for the time window, network area information and optionally a maximum aggregated bitrate, as described in clause 6.1.2.4 of TS 23.503[ Policy and charging control framework for the 5G System (5GS); Stage 2 ]  [20]. This negotiation is preliminarily conducted (when AF initiates a procedure to NEF) before the UE's PDU Session establishment. When the AF wants to apply the Background Data Transfer Policy to an existing PDU Session, then at the time the background data transfer is about to start the AF invokes the Npcf_PolicyAuthorization_Create service directly with PCF, or via the NEF, to apply the background data transfer policy for an individual UE. When the AF wants to apply the Background Data Transfer Policy to a future PDU Session, then the AF invokes Nnef_ApplyPolicy_Create service to provide, to the NEF, the Background Data Transfer Reference ID together with the External Identifier or External Group Identifier of the UE(s) that are subject to the policy. The procedure for BDT warning notification as specified in clause 4.16.7.3 enables the PCF to notify the AF that the network performance in the area of interest goes below the criteria set by the operator as described in clause 6.1.2.4 of TS 23.503[ Policy and charging control framework for the 5G System (5GS); Stage 2 ]  [20].