## 3 Network and Management Data Analytics Functions in the 5G Network Architecture  
The 3 GPP defines the Network Data Analytics Function (NWDAF) in the 5G SBA as a core network function for supporting intelligent and autonomous network operations and service management [22]. NWDAF in the 5G architecture is a general system module through which various data-driven AI/ML-based analytics technologies may be integrated in 5G networks. A general framework for NWDAF-based 5G network automation developed by 3 GPP [30] is depicted in Figure 2. As shown in this figure, the NWDAF collects data from various modules in the 5G system, including NFs, AFs, and data repositories (UDR), for performing the analytics. The obtained analytics information is then delivered by the NWDAF to the NFs/AFs that requested the analytics, which then leverage such information for making decisions about network operations and management actions. The NWDAF also works closely with the network Operation, Administration, and Management (OAM) system within this framework for collecting data from the OAM and exposing analytics information to the OAM. The NWDAF-centric network automation framework is embedded in the 5G SBA. The NWDAF provides a set of analytics services that can be discovered, selected, and accessed by NFs/AFs and consumes the services provided by other system modules (NFs,  
Figure 2: A Network Data Analytics Function (NWDAF)-based framework for 5G network automatic management. UDR, AFs, and OAM) for data collection. The NWDAF communicates with the rest of the framework via the SBI/SCP as defined in the SBA. Cloud-native design of the 5G SBA in principle allows any analytics function to be realized at NWDAF as long as its interactions with other NFs follow the SBI standard and allows NWDAF to leverage various AI/ML technologies for realizing its analytics functions without being constrained by other system modules in the framework [31]. The analytics information generated by NWDAF includes two main categories: statistical information and prediction information. Examples of statistical analytics information provided by the NWDAF include traffic load and resource utilization of network slice instances, network/service performance measurement, and user mobility pattern analysis. Examples of prediction information that can be obtained at the NWDAF include the temporal and spatial traffic distribution predicted for a future time period and user device location prediction for a future time instant. The 5G SBA supports flexible deployment of the NWDAF as a single or multiple VNF instances in the same network domain. Multiple NWDAF instances can be deployed as either a central NF, or a collection of distributed NFs, or a combination of both. When multiple NWDAF instances exist, not all of them need to be able to provide the same type of analytics. Some instances can be specialized in providing certain types of analytics. An analytics ID information element is used to identify the type of analytics that an NWDAF instance can generate. The 5G SBA enables consumers of analytics functions to discover and select an NWDAF instance that is able to provide a specific type of analytics via the NRF. After each NWDAF instance is instantiated, it should register itself at the NRF and provide the list of analytics IDs that it supports as part of the NWDAF profile that will be stored at the NRF. Other NFs may query the NRF for NWDAF discovery and include the analytics ID(s) for the required types of analytics in the query message. Then, the NRF will search the stored NWDAF profiles to discover and select an appropriate NWDAF instance for each query. After discovering an NWDAF instance, the customer NF may employ the SBI request/response messaging protocol to obtain one time analytical information per request. The NF may also subscribe a certain type of analytic service offered by the NWDAF instance, then it will regularly receive notification messages from the NWDAF instance that deliver analytical information generated from the service.