NWDAF shall use the following services to have access to the information provided by OAM:
Generic performance assurance and fault supervision management services as defined in TS 28.532.
PM (Performance Management) services as defined in TS 28.550.
FS (Fault Supervision) services defined in TS 28.545.
NWDAF can be configured to invoke the existing OAM services to retrieve the management data that are relevant for analytics generation, which may include NF resources usage information (e.g. usage of virtual resources assigned to NF) and NF resource configuration information (e.g. life cycle changes of NF resource configurations).
OAM perform the required configuration in order to provide the information requested by NWDAF subscription and perform the tasks, e.g. data collection, data processing, associated with the subscribed request from NWDAF.
Another usage of OAM services is when the target of data collection is a specific UE, via MDT based retrieval of information:
Measurement collection for MDT as defined in TS 37.320.
In addition, NWDAF can be provisioned with Network Slice information (i.e. as defined by the NetworkSliceInfo specified in TS 28.541) when a slice is created or modified via OAM configuration mechanism as defined in TS 28.541 and TS 28.532.
The interactions between NWDAF and OAM for data collection are illustrated in Figure 220.127.116.11-1. The data collected depends on the use cases. This Figure is an abstraction of the OAM performance data file report management service that is defined TS 28.532. The actual OAM services and reporting mechanisms that NWDAF may use are specified in TS 28.532, TS 28.550 or TS 28.545.
The flow below assumes the NWDAF is configured on how to subscribe to the relevant OAM services.
OAM shall setup the required mechanisms to guarantee the continuous data collection requested by NWDAF.
The Correlation information in input data which helps NWDAF correlate data from different NFs, OAM and UE application(s) is defined in Table 6.2.4-1, which is subject to all the network data analytics.
In certain situations, an NWDAF Service Consumer expects to receive analytics by a given time. In particular, when an NWDAF Service Consumer is collecting analytics from multiple NWDAFs it can be necessary to coordinate the timing of the analytics subscriptions/requests from the same NWDAF service consumer.
The NWDAF Service Consumer may use "time when analytics information is needed parameter" (see clause 6.1.3) as a dynamic timer to indicate the minimum time it is going to wait (i.e. "expected waiting time") to receive the analytics collected from multiple NWDAFs.
On analytics request/subscription, the NWDAF Service Consumer indicates the "expected waiting time" as "time when analytics is needed" parameter to those NWDAFs from which it expects to receive the analytics latest by the "time when analytics information is needed", using either the Nnwdaf_AnalyticsInfo_Request or Nnwdaf_AnalyticsSubscription_Subscribe service operation. In this example, NWDAF1 and NWDAF2 are the NWDAFs with tightly related analytics.
[Optional] If the "time when analytics information is needed" is reached, but the analytics is not ready, the NWDAF may indicate a "revised waiting time" in an error response or error notification, using either the Nnwdaf_AnalyticsInfo_Request response or Nnwdaf_AnalyticsSubscription_Notify service operation, depending on the service used in step 1.
[Optional] On receiving an indicated "revised waiting time" as part of an error response or error notification, the NWDAF Service consumer may use the "revised waiting time" to update the "time when analytics information is needed" parameter for future analytics requests/subscriptions to the same group of NWDAFs.
If the value of the "time when analytics information is needed" was updated in step 4, the NWDAF Service Consumer, in future requests or within current subscription, indicates the new expected waiting time as "time when analytics information is needed" to all NWDAFs with tightly related analytics, using either the Nnwdaf_AnalyticsInfo_Request or Nnwdaf_AnalyticsSubscription_Subscribe service operation.