ave smaller buffers, certain GTP-U enhancements specific to the use of GTP-U in RAN have been made, for example, flow control. These enhancements (specific to NG-RAN interfaces), use a GTP-U container, defined in 3GPP TS 29.281, whereas the content of the container is defined in a user-plane protocol specification of a respective NG-RAN interface. This is because even within NG-RAN different interfaces require somewhat different functionality. 3.3.2.3 Standards Traditionally, every NG-RAN (and E-UTRAN) network interface has been defined by a set of five to six specifications. This is, of course, somewhat redundant, as typically some of these specs overlap, partially or even fully. For the most part, what differs between NG-RAN interfaces is the Application Protocol, but for example not the transport. Some effort has been made to improve this situation in 5G; however, it was limited to the definition of a single common user-plane protocol for Xn and F1 (3GPP TS 38.425), as it was considered that the functionality required is very similar. The NG interface still has a separate user-plane specification (3GPP TS 38.415). 3.3.3 NG Interface The NG interface connects NG-RAN to 5GC. It is further divided into NG control plane (NG-C8), connecting NG-RAN to AMF and NG user plane (NG-U9), connecting NG-RAN to UPF. Some key NG-C functions are: Paging, i.e. sending paging messages from 5GC to NG-RAN nodes in the UE's paging area; UE context management, to allow AMF to establish, modify, and release UE context in NG-RAN; UE mobility management, i.e. intra-system (i.e. within 5GS) and inter-system (i.e. between 5GS and EPS) handovers; PDU session management, to allow SMF to establish, modify, and release PDU sessions for a UE; trace, allowing AMF to control trace sessions; AMF load balancing, allowing AMF to indicate its capacity to potentially trigger AMF load balancing within a pool area, and overload control, allowing AMF to control the load NG-RAN generates; NR Positioning Protocol A (NRPPa) signaling transport, for positi