5G Architecture 3gpp:
An NG-RAN node is either:
- a gNB, presenting NR user plane and control plane protocol terminations in the direction of the UE
- an ng-eNB, providing E-UTRA user plane and control plane protocol terminations in the direction of the UE.
The gNBs and new generation [ng-eNBs] are inter-connected with each other by using the Xn interface. The gNBs and [ng-eNBs] are additionally connected by the NG interfaces to the 5GC, more specially to the AMF (Access and Mobility Management Function) with the aid of the NG-C interface and to the UPF (User Plane Function) by way of the NG-U interface.
NOTE: The architecture and the F1 interface for a functional split are described.
The New Generation-(RAN) architecture is defined in Figure above.
Functional Split:The gNB and ng-eNB host the following functions:
- Function for Radio Resource Management [RRM]: Radio Bearer Control [RBC], Radio Admission Control [RAC], Connection
Mobility Control, Dynamic allocation of sources to UEs in each uplink and downlink (scheduling);
IP header compression, encryption and integrity protection facts;
- Selection of an Access Mobility Function at UE attachment while no routing to an AMF may be determined from the statistics supplied by using the UE;
- Routing of User Plane statistics closer to UPF(s);
- Routing of Control Plane statistics toward AMF;
- Connection setup and release;
- Scheduling and transmission of paging messages;
- Scheduling and transmission of device broadcast facts (originated from the AMF or OAM);
- Measurement and dimension reporting configuration for mobility and scheduling;
- Transport level packet marking inside the uplink;
- Session Management;
- Support of Network Slicing;
- QoS Flow management and mapping to statistics radio bearers;
- Support of UEs in RRC_INACTIVE state;
- Distribution feature for NAS messages;
- Radio access community sharing;
- Dual Connectivity;
- Tight interworking between NR and E-UTRA.
The AMF hosts the subsequent essential functions:
- NAS signalling termination;
- NAS signalling security;
- AS Security manipulate;
- Inter CN node signalling for mobility among 3GPP access networks;
- Idle mode UE Reachability (including manage and execution of paging retransmission);
- Registration Area management;
- Support of intra-machine and inter-system mobility;
- Access Authentication;
- Access Authorization including take a look at of roaming rights;
- Mobility management manage (subscription and policies);
- Support of Network Slicing;
- SMF selection.
The UPF hosts the following principal functions:
- Anchor factor for Intra-/Inter-RAT mobility;
- External PDU session factor of interconnect to Data Network;
- Packet routing & forwarding;
- Traffic usage reporting;
- Uplink classifier to guide routing site visitors flows to a data network;
- Branching factor to assist multi-homed PDU session;
- QoS coping with for user plane, e.G. Packet filtering, gating, UL/DL fee enforcement;
- Uplink Traffic verification (SDF to QoS float mapping);
- Downlink packet buffering and downlink facts notification triggering.
The Session Management function (SMF) hosts the following major functions:
- Session Management;
- UE IP cope with allocation and management;
- Selection and control of UP function;
- Configures traffic guidance at UPF to route visitors to right destination;
- Control a part of policy enforcement and QoS;
- Downlink Data Notification.
This is summarized at the figure below wherein yellow bins depict the logical nodes and white packing containers depict the fundamental functions.
