Content for TS 23.503 Word version: 19.1.0

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6.1.4 Network slice related policy control 6.1.4.1 General 6.1.4.2 Limitation of data rate per network slice with assistance of the NWDAF 6.1.4.3 Limitation of data rate per network slice with PCF based monitoring 6.1.5 Group related policy control
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6.1.4 Network slice related policy control |R17| p. 102

6.1.4.1 General p. 102

Network slice related policy control supports limitation of the data rate per network slice.

A Maximum Slice Data Rate can be configured for an S-NSSAI (indicating the network slice subject to network slice data rate limitation control) by the operator (e.g. based on an SLA related to the network slice). The Maximum Slice Data Rate has an UL and a DL value.

The Maximum Slice Data Rate defines the maximum allowed aggregate data rate across all GBR and Non-GBR QoS Flows within the network slice identified by an S-NSSAI.

The PCF monitors the data rate of the network slice and ensures that it does not exceed the Maximum Slice Data Rate for that network slice by e.g. rejecting new SM Policy Associations, rejecting new GBR service data flows with high GBR requirements, changing the Authorized Session-AMBR values (if allowed by the HPLMN), changing the MBR values in PCC rules belonging to GBR service data flows or other actions depending on operator policies. When the PCF rejects the SM Policy Association Establishment procedure to the SMF due to the Maximum Slice Data Rate for that network slice is exceeded, then the SMF rejects the establishment of the PDU Session.

6.1.4.2 Limitation of data rate per network slice with assistance of the NWDAF p. 103

If the NWDAF is used for network slice data rate analysis, the PCF consumes the analytics from the NWDAF and receives the Data Volume Dispersion Analytics statistics outputs for all UEs of the network slice as defined in TS 23.288. The PCF subscribes to the NWDAF for periodic reporting when it becomes responsible for the first PDU Session of a slice (subject to limitation of data rate per network slice) and cancels the subscription when it stops to handle the last PDU Session of that slice.

The NWDAF periodically provides the analytics output to the PCF. The PCF calculates the utilized data rate of the network slice by using the statistics output Data volume dispersed and Duration. When the utilized data rate of the network slice is getting close to or is exceeding the Maximum Slice Data Rate for this S-NSSAI obtained from the UDR, based on operator policy, the PCF may apply a policy decision to strengthen the traffic restrictions for individual PDU Sessions or PCC rules (see clause 6.1.4.1). When the utilized data rate of the network slice falls below the Maximum Slice Data Rate, the PCF may relax the traffic restrictions for individual PDU Sessions or PCC rules.

When multiple PCFs for the same S-NSSAI are deployed, each PCF subscribes to the analytics from the NWDAF separately.

6.1.4.3 Limitation of data rate per network slice with PCF based monitoring p. 103

If the NWDAF is not deployed or is not to be used for network slice data rate analysis, the UDR maintains the Remaining Maximum Slice Data Rate per S-NSSAI and the PCF interacts with the UDR to deduct the value of the authorized Session-AMBR and the MBR of every GBR SDF from the Remaining Maximum Slice Data Rate per S-NSSAI for every PDU Session of this slice. When the Remaining Maximum Slice Data Rate for that S-NSSAI is close to zero, the PCF may, based on operator policies, apply a policy decision to strengthen the traffic restrictions for individual PDU Sessions or PCC rules (see clause 6.1.4.1). When the Remaining Maximum Slice Data Rate for that S-NSSAI increases again, the PCF may relax the traffic restrictions for individual PDU Sessions or PCC rules.

The details on monitoring the data rate per network slice by the PCF are described in clause 6.2.1.10.

6.1.5 Group related policy control |R18| p. 103

Group related policy control supports limitation of the data rate per group and is only applicable to 5G VN groups, as described in clause 5.29.2 of TS 23.501.

The Maximum Group Data Rate defines the maximum allowed aggregate data rate across all GBR and Non-GBR QoS Flows within the 5G VN group.

A Maximum Group Data Rate can be configured for a 5G VN group by the operator or provided by an AF. The Maximum Group Data Rate has an UL and a DL value.

The PCF monitors the data rate of the 5G VN group and ensures that it does not exceed the Maximum Group Data Rate for that group. The method of PCF to realize the above functions is the same as limitation of the data rate per network slice as defined in clauses 6.1.4.1 and 6.1.4.3 with the following differences:

Instead of handling Maximum Slice Data Rate per S-NSSAI, the UDR and PCF handles the Maximum Group Data Rate per 5G VN group.
Instead of deducting the value of the authorized Session-AMBR and the MBR of every GBR SDF for every PDU Session of the slice, the PCF deducts such value for every PDU Session accessing to the 5G VN group.

The PCF may receive the Maximum Group Data Rate as part of the 5G VN group data (within the subscription data set), as described in clause 5.29 of TS 23.501. The PCF(s) that have subscribed to modifications of 5G VN group data receive(s) a Nudr_DM_Notify notification in case the 5G VN group data has changed in UDR. In both cases, if the values of the Maximum Group Data Rate in 5G VN group data and 5G VN Group specific policy control information are different, the PCF shall update the Maximum Group Data Rate in the 5G VN Group specific policy control information and adjust the Remaining Maximum Group Data Rate in the 5G VN Group specific policy control information accordingly.