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Content for  TS 23.288  Word version:  17.5.0

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6.3  Slice load level related network data analyticsp. 98

6.3.1  Generalp. 98

The NWDAF provides slice load level information to a consumer NF on a Network Slice level or a Network Slice instance level or both. The NWDAF is not required to be aware of the current subscribers using the slice. The NWDAF notifies slice specific network status analytics information to the consumer NF that is subscribed to it. A consumer NF may collect directly slice specific network status analytics information from NWDAF. This information is not subscriber specific.
The NWDAF services as defined in the clause 7.2 and clause 7.3 are used to expose slice load level analytics from the NWDAF to the consumer NF (e.g. PCF, NSSF or AMF).
The consumer of these analytics shall indicate in the request or subscription:
  • Analytics ID = "Load level information";
  • Analytics Filter Information:
    • S-NSSAI and NSI ID;
    • optionally, the list of analytics subsets that are requested among those specified in clause 6.3.3A;
  • an optional Area of Interest;
  • an optional list of NF types;
  • optionally, Load Level Threshold value;
  • optionally, "maximum number of objects" indicating the maximum number of Network Slice instances expected in output, when the Analytics Filter Information does not indicate an NSI ID; and
  • an Analytics target period indicating the time period over which the statistics or predictions are requested.
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6.3.2Void

6.3.2A  Input datap. 99

The detailed information collected by the NWDAF is listed in Table 6.3.2A-1 and Table 6.3.2A-2.
Information Source Description
UE registered in a Network Slice/Network Slice instanceOAMMean number of UEs registered in a NW slice or NW slice instance as defined in TS 28.552. (NOTE 1).
PDU Session established on a Network Slice/Network Slice instanceOAMMean number of established PDU Sessions in a NW slice or NW slice instance as defined in TS 28.552. (NOTE 1).
Load of NFs associated to Network Slice instanceOAM Resource utilization information of a Network Slice instance obtained from its constituent NF instances. NF instance load input data collection is described in clause 6.5, Table 6.5.2-1.
NOTE 1:
5GC performance measurements can be provided per S-NSSAI by OAM as defined in TS 28.552. Any 5GC performance measurements per NSI ID required further coordination with SA WG5.
Information Source Description
Timestamps5GC NFA time stamp associated with the collected information.
UE registers/de-registers to a Network Slice/Network Slice instanceAMF(s)AMF reports that a UE registered or deregistered to a S-NSSAI or to a S-NSSAI and NSI ID.
Number of UEs served by the AMFAMF(s)AMF reports the total number of UEs served by the AMF per S-NSSAI or per S-NSSAI and NSI ID. (NOTE 1)
PDU Session established/released on a Network SliceSMF(s)SMF reports that a PDU Session is established or released per S-NSSAI or per S-NSSAI and NSI ID.
Current number of UEs registered in a NW sliceNSACFNSACF reports the number of UE registered at the S-NSSAI.
Current number of PDU Sessions established in a NW sliceNSACFNSACF reports the number of PDU Sessions established at the S-NSSAI.
Load of NFs associated to Network Slice instanceNRF Resource utilization information of a Network Slice instance obtained from its constituent NF instances. NF instance load input data collection is described in clause 6.5, Table 6.5.2-1.
NOTE 1:
AMF reports the total number of registered UE in the AMF at each associated time stamp.
NOTE 2:
SMF reports multiple PDU Sessions when establishment or release happened at the same time, indicated by the time stamp.
NOTE 3:
Based on the internal logic, the NWDAF determines the source for the data collection.
NWDAF collects input data on the number of UEs registered in a S-NSSAI or S-NSSAI and NSI combination using one of the following options:
  • Total number of UE registered to a S-NSSAI or to a S-NSSAI and NSI ID from each AMF(s) and/or from NSCAF:
    • Namf_EventExposure_Subscribe (Target for Event Reporting = "any UE", Event ID = "Number of UEs served by the AMF and located in "Area of Interest"", Event Filter information = S-NSSAI(s) or one or more of the tuple (S-NSSAI, NSI ID), Event reporting mode = periodic along with periodicity) as defined in clause 5.2.2.3.1 of TS 23.502; or
    • Nnsacf_SliceEventExposure_Subscribe (EventID = "Number of UE registered", EventFilter = "S-NSSAI", Event reporting mode = periodic along with periodicity) as defined in clause 5.2.21.4.2 of TS 23.502.
  • Individual UE registration/deregistration to a S-NSSAI or to a S-NSSAI and NSI ID reported by AMF(s):
    • Namf_EventExposure_Subscribe (Target for Event Reporting = "any UE", Event ID = "UE moving in or out of a subscribed "Area of Interest"", Event Filter information = S-NSSAI(s) or one or more of the tuples (S-NSSAI, NSI ID), Event reporting mode = reporting to a maximum number or a maximum duration) as defined in clause 5.2.2.3.1 of TS 23.502.
NWDAF collects input data on the number of PDU Sessions established in a S-NSSAI using one of the following options:
  • Total number of PDU Sessions established in a S-NSSAI from each SMF(s) and/or NSACF:
    • Nnsacf_SliceEventExposure_Subscribe (EventID = "Number of PDU sessions established", EventFilter = "S-NSSAI(s)", Event reporting mode = periodic along with periodicity) as defined in clause 5.2.21.4.2 of TS 23.502.
  • Individual PDU Session Established or PDU Session Released in a S-NSSAI from SMF:
    • Nsmf_EventExposure_Subscribe (Target for Event Reporting = "any UE", Event ID = "PDU Session Establishment and/or PDU Session Release", Event Filter information = S-NSSAI(s), Event reporting mode = reporting to a maximum number or a maximum duration) as defined in clause 5.2.8.3.1 of TS 23.502.
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6.3.3Void

6.3.3A  Output analyticsp. 100

The NWDAF services as defined in the clause 7.2 and clause 7.3 are used to expose the following analytics:
  • Network Slice instance load statistics information as defined in Table 6.3.3A-1.
  • Network Slice load statistics information as defined in Table 6.3.3A-2.
  • Network Slice instance load predictions information as defined in Table 6.3.3A-3.
  • Network Slice load predictions information as defined in Table 6.3.3A-4.
Information Description
S-NSSAIIdentification of the Network Slice.
Network Slice instances (1..max)List of Network Slice instance(s) within the S-NSSAI.
> NSI IDIdentification of the Network Slice instance.
> Number of UE Registrations (NOTE 1)Number of UE registrations of the Network Slice instance (average, variance).
> Number of PDU Sessions establishment (NOTE 1)Number of PDU Session establishments of the Network Slice instance (average, variance).
> Resource usage (NOTE 1)The usage of assigned virtual resources currently in use for the NF instances (mean usage of virtual CPU, memory, disk) as defined in TS 28.552, clause 5.7, belonging to a particular Network Slice instance.
> Resource usage threshold crossings (NOTE 1)Number of times resource usage threshold is met or exceeded or crossed on the Network Slice instance provided if threshold is provided by the consumer as Analytics Filter.
> Resource usage threshold crossings time period (1..max) (NOTE 1, NOTE 2)Resource usage threshold crossing vector including time elapsed between times each threshold is met or exceeded or crossed on the Network Slice instance if a threshold value is provided by the consumer as Analytics Filter.
> Load Level (NOTE 1)The load level of the Network Slice Instance indicated by the S-NSSAI and the associated NSI ID (if applicable) in the Analytics Filter, if Load Level Threshold is not provided by the consumer as Analytics Filter.
> Crossed Load Level Threshold (NOTE 1)The Load Level Threshold that are met or exceeded by the statistics value of the Load Level if the Load Level Threshold is provided by the consumer as Analytics Filter.
NOTE 1:
Analytics subset that can be used in "list of analytics subsets that are requested".
NOTE 2:
The time period is a time interval specified by a start time and an end time timestamps within the Analytics target period.
Information Description
S-NSSAIIdentification of the Network Slice.
> Number of UE Registrations (NOTE 1)Number of UE registrations at the Network Slice (average, variance).
> Number of PDU sessions establishments (NOTE 1)Number of PDU Session establishments at the Network Slice (average, variance).
> Load Level (NOTE 1)The load level of the Network Slice Instance indicated by the S-NSSAI and the associated NSI ID (if applicable) in the Analytics Filter, if Load Level Threshold is not provided by the consumer as Analytics Filter.
> Crossed Load Level Threshold (NOTE 1)The Load Level Threshold that are met or exceeded by the statistics value of the Load Level if the Load Level Threshold is provided by the consumer as Analytics Filter.
NOTE 1:
Analytics subset that can be used in "list of analytics subsets that are requested".
Information Description
S-NSSAIIdentification of the Network Slice.
Network Slice instances (1..max)List of Network Slice instance(s) within the S-NSSAI.
> NSI IDIdentification of the Network Slice instance.
> Number of UE Registrations (NOTE 1)Number of predicted UE registrations at the Network Slice instance (average, variance).
> Number of PDU Sessions establishment (NOTE 1)Number of predicted PDU Session establishments of the Network Slice instance (average, variance).
> Resource usage (NOTE 1)The predicted usage of assigned virtual resources for the NF instances (mean usage of virtual CPU, memory, disk) as defined in TS 28.552, clause 5.7, belonging to a particular Network Slice instance.
> Resource usage threshold crossings (NOTE 1)Number of predicted times resource usage threshold is met or exceeded or crossed at the Network Slice instance provided that a threshold value is provided by the consumer as Analytics Filter.
> Resource usage threshold crossings time period (1..max) (NOTE 1, NOTE 2)Predicted Resource usage threshold vector including predicted time elapsed between times each threshold is met or exceeded or crossed on the Network Slice instance if a threshold value is provided by the consumer as Analytics Filter.
> Load Level (NOTE 1)The load level of the Network Slice Instance indicated by the S-NSSAI and the associated NSI ID (if applicable) in the Analytics Filter, if Load Level Threshold is not provided by the consumer as Analytics Filter.
> Crossed Load Level Threshold (NOTE 1)The Load Level Threshold that are met or exceeded by the predicted value of the Load Level if the Load Level Threshold is provided by the consumer as Analytics Filter.
> ConfidenceConfidence of this prediction.
NOTE 1:
Analytics subset that can be used in "list of analytics subsets that are requested".
NOTE 2:
The time period is a time interval specified by a start time and an end time timestamps within the Analytics target period.
Information Description
S-NSSAIIdentification of the Network Slice.
> Number of UE Registrations (NOTE 1)Predicted Number of UE registrations at the Network Slice (average, variance).
> Number of PDU sessions establishments (NOTE 1)Predicted Number of PDU Session establishments at the Network Slice (average, variance).
> Load Level (NOTE 1)The load level of the Network Slice Instance indicated by the S-NSSAI and the associated NSI ID (if applicable) in the Analytics Filter, if Load Level Threshold is not provided by the consumer as Analytics Filter.
> Crossed Load Level Threshold (NOTE 1)The Load Level Threshold that are met or exceeded by the predicted value of the Load Level if the Load Level Threshold is provided by the consumer as Analytics Filter.
> ConfidenceConfidence of this prediction.
NOTE 1:
Analytics subset that can be used in "list of analytics subsets that are requested".
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6.3.4  Procedures |R17|p. 103

Reproduction of 3GPP TS 23.288, Fig. 6.3.4-1: Network Slice load analytics provided by NWDAF
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Figure 6.3.4-1 shows the procedure for NWDAF to derive slice load analytics. The steps are described as follows:
Step 1.
A consumer NF subscribes to/requests a NWDAF using Nnwdaf_AnalyticsSubscription_Subscribe or Nnwdaf_AnalyticsInfo_Request service operation (Analytics ID = Load level information and a set of Analytics Filters (e.g. S-NSSAI, NSI ID, Area of Interest)).
Step 2.
[OPTIONAL] If the NWDAF does not have already the slice information, it gains the slice information from OAM (as described in clause 6.2.3) and discovers from NRF the AMF, SMF and NSSF instance(s) relevant to the Analytics Filters provided in the analytics subscription.
Step 3.
[OPTIONAL] If the NSI ID(s) are not provided in the analytics subscription by the consumer NF, the NWDAF invokes Nnssf_NSSelection_Get service operation from NSSF to obtain the NSI ID(s) corresponding to the S-NSSAI in the subscription.
Step 4a.
[CONDITIONAL] The NWDAF may subscribe to input data in Table 6.3.2A-1 from the OAM according to the data collection principles from the OAM described in clause 6.2.3.
Step 4b.
[CONDITIONAL] The NWDAF may collect input data from the NRF (see clause 6.5) to derive slice instance resource usage statistics and predictions for a Network Slice instance.
Step 5.
[CONDITIONAL] The NWDAF may subscribe to the AMF(s) event exposure service to collect data on the number of UEs currently registered on certain Network Slice and, if available, its constituent Network Slice instance(s) as defined in clause 6.3.2A. If required, the NWDAF may also collect the corresponding UE IDs.
Step 6.
[CONDITIONAL] The NWDAF may subscribe to the SMF(s) event exposure service to collect data on the number of PDU sessions established and/or released at the SMF on currently registered on certain Network Slice as defined in clause 6.3.2A. NWDAF can then use such collected data to determine the number of PDU sessions established on i) a Network Slice; and ii) if available, on a Network Slice instance by leveraging the data collected in step 5.
Step 7.
[CONDITIONAL] The NWDAF may subscribe to one or multiple NSACFs to collect data on either the number of UE registered in a S-NSSAI or the number of PDU sessions established in a S-NSSAI as defined in clause 6.3.2A. When multiple NSACFs are selected by the NWDAF for the S-NSSAI, the NWDAF aggregates the reports from the NSACFs to derive the number of UEs registered in the S-NSSAI or the number of PDU sessions established in the S-NSSAI.
Step 8.
The NWDAF derives slice load analytics.
Step 9.
The NWDAF delivers analytics to the consumer NF by invoking Nnwdaf_AnalyticsSubscription_Notify or Nnwdaf_AnalyticsInfo_Request response service operations.
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