Section: 5.7.2.2 ARP
Content: The QoS parameter ARP contains information about the priority level, the pre-emption capability and the pre-emption vulnerability. This allows deciding whether a QoS Flow establishment/modification/handover may be accepted or needs to be rejected in the case of resource limitations (typically used for admission control of GBR traffic). It may also be used to decide which existing QoS Flow to pre-empt during resource limitations, i.e. which QoS Flow to release to free up resources. The ARP priority level defines the relative importance of a QoS Flow. The range of the ARP priority level is 1 to 15 with 1 as the highest priority. The ARP priority levels 1-8 should only be assigned to QoS Flows for services that are authorized to receive prioritized treatment within an operator domain (i.e. that are authorized by the serving network). The ARP priority levels 9-15 may be assigned to QoS Flows for services that are authorized by the home network and thus applicable when a UE is roaming. NOTE: This ensures that future releases may use ARP priority level 1-8 to indicate e.g. emergency and other priority services within an operator domain in a backward compatible manner. This does not prevent the use of ARP priority level 1-8 in roaming situation in the case that appropriate roaming agreements exist that ensure a compatible use of these priority levels. The ARP pre-emption capability defines whether a QoS Flow may get resources that were already assigned to another QoS Flow with a lower priority. The ARP pre-emption vulnerability defines whether a QoS Flow may lose the resources assigned to it in order to admit a QoS Flow with higher priority. The ARP pre-emption capability and the ARP pre-emption vulnerability shall be either set to 'enabled' or 'disabled'. The ARP pre-emption vulnerability of the QoS Flow which the default QoS rule is associated with should be set appropriately to minimize the risk of a release of this QoS Flow. The details of how the SMF sets the ARP for a QoS Flow are further described in clause 5.7.2.7.