Section: 6.3.9 Handling of APN rate control
Content: APN rate control controls the maximum number of uplink user data messages including uplink exception data reporting sent by the UE in a time interval for the APN in accordance with 3GPP TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [10]. The UE shall limit the rate at which it generates uplink user data messages to comply with the APN rate control policy. The NAS shall provide the indicated rates to upper layers for enforcement. The indicated rates in a NAS procedure applies to the APN the NAS procedure corresponds to, and the indicated rates are valid until a new value is indicated or the last PDN connection using this APN is released. If the UE supports APN rate control, the UE shall provide the support indication of APN rate control and additional APN rate control for exception data reporting to the network. If the UE indicates support of additional APN rate control for exception data reporting, the network may provide the APN rate control parameters for exception data to the UE. If the UE does not indicate support of additional APN rate control for exception data reporting, the network shall not provide the APN rate control parameters for exception data to the UE. If an allowed indication of additional exception reports is provided with the APN rate control parameters and: - the additional APN rate control parameters for exception data is provided and the limit for additional rate for exception data reporting is not reached; or - the additional APN rate control parameters for exception data is not provided, the UE is allowed to send uplink exception reports even if the limit for the APN rate control has been reached. NOTE 1: The HPLMN can discard or delay user data that exceeds the limit provided for APN rate control. Upon inter-system change from S1 mode to N1 mode, the UE shall store the current APN rate control status for each APN associated with PDN connection(s) to be transferred from S1 mode to N1 mode as specified in 3GPP TS 23.501[ System architecture for the 5G System (5GS) ]  [58]. NOTE 2: How long the UE stores the current APN rate control status is implementation specific. Upon inter-system change from N1 mode to S1 mode, the UE shall use the stored APN rate control status, if any, to comply with the APN rate control policy for an APN as specified in 3GPP TS 23.501[ System architecture for the 5G System (5GS) ]  [58] if: a) there is at least one PDN connection associated with this APN was transferred from N1 mode to S1 mode; and b) the validity period of the stored APN rate control status has not expired. After inter-system change from S1 mode to N1 mode, if all the PDU sessions associated with the same APN that was used in S1 mode are released, the UE shall delete the stored APN rate control status for this APN.