ications to provide information about the expected UE behavior (e.g. the UE's expected mobility pattern) to 5GC; Policy/charging capability to allow applications to request QoS and charging treatment for specific flows. Additional auxiliary 5GC functions include: The Unified Data Management (UDM), which is the equivalent of the Home Subscriber Server in EPC and performs subscriber data management. The Network Repository Function (NRF) allows for dynamic discovery of other network functions, e.g. enables AMF to discover an SMF when a UE requests to establish a PDU session. To support this, APIs have been specified (3GPP TS 29.510) for network functions to register their own profile (e.g. network type, supported network slices, etc.) with the NRF and APIs to enable network functions to query NRF. In the case of EPC, only query functionality was specified (network function registration was left to implementation) and was realized using the Domain Name System (DNS) (3GPP TS 29.303). The Network Slice Selection Function (NSSF) determines the set of network slice instances to serve a UE (see Section 3.2.6 for further details about network slicing). 3.2.3 Control-User Plane Separation (CUPS) The motivation for separating control-from user-plane functionality is twofold: Independent scaling of control- and user-plane processing capacity; Increased flexibility when deploying control-plane functions and user plane functions, e.g. to enable operators to locate control-plane functions in a central location (e.g. in a data center) while placing UPFs close to the RAN. It is worth noting that the ability to deploy user-plane functionality close to the RAN is a key enabler for efficient access to localized services (see Section 3.2.5 for further details). CUPS has initially been studied and specified for EPS. As described in 3GPP TS 23.214 and as depicted in Figure 3.2.3, CUPS has been realized as an extension to the existing EPC architecture by splitting SGW and PGW into their control- and user-plane components. The SGW control