IEs Supported for Offline Charging Reporting

Feature History

Feature Name

Release Information

Description

Recalculate Measurement IE on the N4 Interface

2023.04

UPF supports the Recalculate Measurement custom IE as received over the N4 interface. This IE is added to the Update-URR process (URR-ID: Gz-Bearer) to support the PGW-CDR generation due to the max_LOSDV change condition.

The following trigger Information Elements (IEs) support offline charging Reporting over N4:

  • Periodic Reporting – When this trigger is set, the UPF sends resource usage report periodically to Session Management Function (SMF). The intervals that are required for periodic reporting are sent with the measurement period IE.

  • Volume Threshold (when the volume threshold reaches UL, DL, and Total) – This trigger is set when the volume-based measurement is required. The SMF sends the traffic volume value along with the volume threshold IE, while the UPF sends the traffic usage report when the traffic volume is reached for the specific Usage Reporting Rule (URR).

  • Time Threshold (when the time threshold is reached) – This trigger is set when the time-based measurement is set. The SMF sends the time threshold value along with the time threshold IE, while the UPF sends resource usage report when the time threshold is reached for the specific URR.

  • Linked Usage Reporting – The UPF sends the usage report of this specific URR when this trigger is set. In addition, the usage report is sent to any of the URRs linked to UPF when this trigger is set. The UPF sends the linked URR-Id along with the linked URR-Id IE.

  • Packet Forwarding Control Protocol (PFCP) Session Deletion – A usage report generates (in a PFCP Deletion Response) for a URR due to the termination of the PFCP session. Similarly, a usage report generates (in a PFCP modification response) for a URR due to the removal of a specific URR.

  • Update URR – This trigger is set when update URR request is received.

  • Recalculate Measurement – The custom Information Element (IE) called Recalculate Measurement is added to the Update-URR process (URR-ID: Gz-Bearer) to support the PGWCDR generation due to the Max-LOSDV condition. After receiving the IE, UPF reconcile the Volume and Duration of the URR according to the URR-ID present inside the IE.

    Note
    • The total usage for the given URR-ID is reset, and if there are any linked URRs, the usage is recalculated.

    • The timestamps for first-pkt-time, last-pkt-time and duration are also adjusted accordingly.

    • The threshold values remain unchanged.

  • Recalculate Interface - The custom IE called ‘Recalculate Interface’ is sent by SMF via N4 Modify Request. When Recalculate Interface IE is received along with Query URR(s) or Update URR(s) IEs in the same Sx Modify Request, Recalculate Interface IE will be processed independently in the end. After receiving the IE, the UPF iterates through all the URRs, fetching only the URRs mentioned as per the flags mentioned by SMF and execute the recalculate functionality. The UPF subsequently reconciles the Volume and Duration of all the retrieved URRs.

    Note
    • The usage accumulated for the URRs is discarded, and if there are any linked URRs, their usage is reconciled.

    • The timestamps for first-pkt-time, last-pkt-time and duration are adjusted accordingly.

    • The threshold values for the linked URRs remain unchanged.