5G Core Architecture Part 1 Live Session on 6th April 2021

The Topics Covered in Part 1 of the Session are :
High Level 5G System
5G reference point Architecture
PDU Sessions and QoS Flow
5G Network Functions
AMF
SMF
UPF
PCF
UDM

AMF :
1. As a mobile network comprises many AMF instances, a Globally Unique AMF Identifier (GUAMI) is allotted to each AMF.
AMF Performs the role of access point to the 5G core,
3. AMF implements NAS ciphering and integrity protection algorithms
4. In order to send applicable and appropriate event information, the AMF connects to Lawful Intercept (LI) system
5. As part of mobility management, the AMF is in charge for managing handovers between gNodeB’s (gNB’s), within the Next Generation Radio Access Network (NG-RAN)

SMF:
The SMF is primarily responsible for interacting with the decoupled data plane, creating updating and removing Protocol Data Unit (PDU) sessions and Managing session context with the User Plane Function (UPF).

UPF:
1. The UPF is interconnect point between the mobile infrastructure and the Data Network (DN), i.e. encapsulation and decapsulation of GPRS Tunneling Protocol for the user plane (GTP‑U).
2. It is the Protocol Data Unit (PDU) session anchor point for providing mobility within and between Radio Access Technologies (RATs), including sending one or more end marker packets to the gNB.
3. It does Packet routing and forwarding, including performing the role of an Uplink Classifier / UL-CL (directing flows to specific data networks based on traffic matching filters) and a Branching point, when acting as an Intermediate UPF (I-UPF) multi-homed to more than one PDU session anchor (PSA).
4. It does application detection using Service Data Flow (SDF) traffic filter templates or 3-tuple (protocol, server-side IP address and port number) Packet Flow Description (PFD) received from the SMF.
5, It does Per-flow QoS handling, including transport level packet marking for uplink (UL) and downlink (DL), rate limiting and reflective QoS (DSCP) marking on the DL.
6. It does traffic usage reporting for billing and the Lawful Intercept (LI) collector interface

UDM:
1. It contains Central Registry of Subscriber information and data network profile
2. Involved in Access Authorisation
3. Involved in Registration and Mobility management
4. Tells AMF and SMF what is allowed /not allowed .Which QoS profile / data network they can connect to etc

PCF:
1. It takes dynamic decision based on present Network Condition. For Example, if a subscriber is in a area where no cell is there, it may ask SMF to throttle the subscriber or even do not allow PDF session itself.
2. Decides on correct resource allocation .