5G Usage Trigger Behavior

Usage triggers operate on the session or rating group level. The 5G GFBR_GUARANTEED_STATUS_CHANGE AVP is specified to be scoped for rating group only.

The SMF requests quota from the CHF when a specific trigger type is received in the usage report from the UPF. After authorizing quota, usage trigger components are collected from all active offers of the same service type. Each of these components indicates whether it should be evaluated for sessions or for rating groups. These components are then evaluated once for the session, and once per rating group in the session that has been granted quota, resulting in a separate list of triggers for each.

Each list includes the union of all triggers selected by the evaluated components. For example, if triggers A and B are selected by usage trigger component #1 and triggers B and C are selected by usage trigger component #2, the list includes triggers A, B, and C.

For 5G N40 charging, each session (and its rating groups that have been granted quota) arms triggers from its own list. For example, if the session has a list containing triggers A and B and the rating group has a list containing triggers B and C, then the session arms triggers A and B, and the rating group arms triggers B and C. If a second rating group has a list containing triggers B and D, then that rating group arms triggers B and D.

Immediate Reporting

When a usage trigger is immediate and the SMF encounters a rating change condition, such as when a tariff time change (TTF) boundary is reached or a subscriber changes cell towers, it sends a 5G Charging Data Request message to MATRIXX Engine and the usedUnitContainer AVP has the used units and trigger type/condition (tariff time change, validity time (reserved time), quota exhausted). A session field mapping evaluates the trigger type and MATRIXX Engine initiates rating to calculate the cost to the subscriber's balances.

Deferred Reporting

When a usage trigger is deferred, the SMF stores rating change conditions and their unit values and then sends all usedUnitContainer values in the same 5G Charging Data Request message. The event generated for a deferred trigger category only refers to the first evaluated trigger type condition. The used units refer to all totalVolume amounts in the multiple usedUnitContainer AVPs received in the 5G charging data request message.