5.51.2.2.2 Energy Consumption information collection from SMF

The serving SMFs are retrieved by the EIF from the UDM of the UE based on the provided input parameters including the UE ID and optional S-NSSAI or (S-NSSAI, DNN). Also, the EIF subscribes to the UDM to be notified with the applicable SMFs.

The EIF invokes Nsmf_EventExposure_Subscribe as defined in TS 23.502 [3] with the required granularities (UE ID, DNN/S-NSSAI, application information (i.e. Application Identifier, or Packet Filters)) to retrieve the information from SMF, which is shown in Table 5.51.2.2.2-1. The SMF receives the data volume of the required granularities from the PSA UPF. Whenever necessary for describing a specific data path scenario of a PDU Session, the SMF can generate relevant an NF specific Data Volume (UL or DL or both) (see Table 5.51.2.2.2-2) based on the data volume reported by the PSA UPF and provide it to the EIF as well, e.g., in case of the scenarios described in clauses 5.6.4, 5.33.2.2 and 5.33.2.3.

NOTE 1: In the case of redundant PDU Session for single SMF case, SMF uses the data volume reported by PSA UPF as Common UL and DL Data Volume (see Table 5.51.2.2.2-2) to represent the data volume handled by gNB and by each I-UPF if any while NF specific Data Volume (UL or DL or both) is used to represent the actual data volume handled by PSA UPF so that both original and duplicated data volume can be represented. In the case of PDU Session with multiple PDU Session Anchors, SMF uses the sum of the data volumes reported by PSA UPFs as Common UL and DL Data Volume to represent the actual data volume handled by gNB and by I-UPF while NF specific Data Volumes (UL or DL or both) whose value is set as the data volume reported by each PSA UPF are used for each PSA UPF.

NOTE 2: The data volumes provided by the SMF refer to the "access side" of the NFs, i.e., Uu interface for gNB, N3 interface for I-UPF and N3/N9 interfaces for PSA UPF, in order to keep them aligned with OAM measurement on Node-level data volume (see Table 5.51.2.2.3-1) which is used for the Energy Consumption calculation.

The SMF derives the gNB ID(s) from the AMF provided ULI as described in clause 4.3.2. If the I-SMF is involved in the PDU session, the I-SMF reports to the SMF of PDU session via Nsmf_PDUSession_Update the current I-UPF ID and subsequent change of the I-UPF ID(s). If the I-SMF is involved in the PDU session, the SMF of PDU session requests the I-SMF via Nsmf_PDUSession_Update to report the current ULI and subsequent change of ULI only when the gNB ID changes.

The SMF then sends the data volumes, along with the serving gNB ID(s) and (I-)UPF ID(s) to EIF for energy consumption calculation. The information collected from SMF by EIF, is shown in Table 5.51.2.2.2-2. Upon release of a PDU session, the SMF terminates subscriptions related to the PDU session and indicates the subscription termination to the EIF. The SMF periodically notifies EIF with the information at the end of each time interval T until the EIF unsubscribes as defined in TS 23.502 [3]. The SMF shall collect data volume only for the PDU session carried over the 3GPP Access in 5GS. When the PDU session is over Non-3GPP Access type, or it is a PDN connection over EPS handled at a SMF+PGW-C, the SMF reports UL/DL Data volume in the measurement period equal to 0 (zero) and the gNB ID is not provided.

NOTE 3: The SMF can derive gNB ID(s) according to the AMF provided ULI as described in clause 4.3.2 of TS 23.502 [3].

In the case of MA PDU session, the SMF shall not include in the report the UL/DL Data volume related to the traffic over the Non-3GPP access leg and the serving gNB ID refers to the traffic over the 3GPP leg.

For the PDU session whose S-NSSAI is replaced without PDU session re-establishment, the SMF continues the reporting for the replaced S-NSSAI and the SMF uses the Usage Report including the Alternative S-NSSAI received from the UPF for the report to the EIF for the replaced S-NSSAI.

When the SMF receives the Nsmf_EventExposure_Subscribe with application information (i.e. Application Identifier, or Packet Filters) from the EIF for energy consumption, the SMF generates a URR for the Data Volume counting with a Periodic measurement threshold set according to the Timer interval T and associates the subscription from EIF to the generated URR. The SMF is then associating the generated URR to an appropriate PDR. SMF logic ensures that the PDRs and their precedence values are configured appropriately in the UPF so that both, the URRs for Data Volume counting for EIF and the traffic handling instructions derived from the existing PCC rules can co-exist and the traffic is treated in the same way as before. For example, when the SMF receives the Nsmf_EventExposure_Subscribe with application information, the SMF may behave as follows:

• If there is an existing PCC rule for exactly the same Service Data Flow as the application information in the energy consumption request (i.e. with same Application Identifier or same Packet Filters), the SMF associates the generated URR with the PDR of that PCC rule.
• If there is no PCC rule matching with the application information in the energy consumption request (i.e. the Application Identifiers are different or no packet filter overlap exists) but a match-all PDR has been provisioned for the PDU Session, the SMF generates a PDR for the application information and associates the generated URR with that PDR. All other instructions of the PDR related to the match-all PCC rule are copied (so that the traffic is treated in the same way as before).

NOTE 4: For the Data Volume counting, the SMF can only generate a PDR in compliance with the Service Data Flows templates in the PCC rules provided by PCF or the local policy. To achieve this, it is recommended that the EIF provides the same type of application information (i.e. Application Identifier, or Packet Filters) in the Nsmf_EventExposure_Subscribe as that of the Service Data Flows templates in PCC rules, e.g. based on operator configuration.

NOTE 5: The SMF may be unable to determine the matching or overlapping PCC rule(s) and PDR(s) if the PCC rule includes an Application Identifier and the EIF provides Packet Filters, or vice versa.

• If the application information in the energy consumption request is partially overlapping with the Service Data Flow(s) of (one or more) existing PCC rule(s) other than the match-all PCC rule (which can only occur when the subscription contains Packet Filters), the SMF may need to generate two or more PDR(s). For the PDR(s) with overlapping packet filters, the SMF associates the generated URR with the(se) PDR(s) and copies all other instructions of the PDR(s) related to the existing PCC rule(s) with overlap. SMF also associates the generated URR to the PDR with the non overlapping packet filters (if any), and it copies all other instructions of the PDR related to the match-all PCC rule. This ensures that both, the Data Volume counting for EIF and the traffic handling instructions derived from the existing PCC rule(s) and the match-all PCC rule can be realized.

NOTE 6: One or more of the above can apply to an energy consumption request.

NOTE 7: For a MA PDU Sessions, the generated URRs are only included for the 3GPP access in the Multi-Access Rule (see clause 5.8.5.8).

If the PCC rules are changed, the SMF shall again perform the above checks and actions.

If predefined PCC rules (see clause 5.8.2.8.1) associated to packet detection rules locally defined in UPFs (see TS 29.244 [65]) are used for the PDU Session, the procedure described above requires that the SMF also needs to be aware of the semantics of such rules in order to behave as described above and avoid conflicts if they arise. If the SMF is not aware of the semantics, then the SMF should reject requests that could conflict with packet detection rules locally defined in UPFs.

When the SMF receives the Nsmf_EventExposure_Subscribe for the PDU Session from the EIF (i.e. no application information is provided by the EIF), the SMF associates the subscription from EIF to the PDU Session, generates a URR for the Data Volume counting (with a Periodic measurement threshold set according to the Timer interval T) and associates it with all PDRs of the PDU Session.

In both cases, the UPF will send the collected data volume information of this URR at the end of each Time interval to the SMF in a Usage Report (see clause 4.4.2.2 of TS 23.502 [3]). If there is a change in the user plane path (e.g. handover between gNBs or insertion/removal of I-UPF) during the Time interval, the SMF shall request the collected data volume information of this URR from the UPF. If this happens, the UPF will immediately send the collected data volume information to the SMF in a Usage Report (see clause 4.4.2.2 of TS 23.502 [3]) and the SMF shall then store this information together with the gNB ID and I-UPF ID that belong to the user plane path before the change happened.

Table 5.51.2.2.2-1: Information to SMF for user-plane energy consumption calculation

NOTE 8: The user-plane energy consumption information reporting interval from the SMFs is the network-wide configurable starting time and interval T.

Table 5.51.2.2.2-2: Information from SMF for user-plane energy consumption calculation