What are the core components of the 5G ecosystem (NG-RAN and 5G core), and how do they map onto the 4G equivalents?
The 5G ecosystem is UE ↔ NG-RAN (gNB base stations) ↔ 5G Mobile Core (AMF, SMF, UPF). The gNB replaces the eNB; the AMF takes over access/mobility management (like the MME), the SMF handles sessions, and the UPF handles user-plane forwarding (splitting the old S-GW/P-GW role).
* How 4G EPC nodes map onto 5G network functions. *
* UE to NG-RAN to 5G Core. — GiftedYeti, CC BY-SA 4.0, via Wikimedia Commons. *
The 5G ecosystem:
UE ⇄ NG-RAN (gNB) ⇄ 5G Mobile Core (AMF, SMF, UPF) ⇄ Internet/Data Network
Main components:
| Component | Full name | Role |
|---|---|---|
| gNB | next-generation NodeB | the 5G base station |
| AMF | Access and Mobility Management Function | authentication, mobility |
| SMF | Session Management Function | session management |
| UPF | User Plane Function | user-data forwarding |
Mapping from 4G:
| 4G | 5G |
|---|---|
| eNB | gNB |
| MME (control/mobility) | AMF |
| (session aspects) | SMF |
| S-GW + P-GW (user plane) | UPF |
The key structural change: in 4G the control and user planes were partially intertwined in the gateways; in 5G they are cleanly separated into distinct functions — AMF/SMF on the control plane, UPF on the user plane. This separation is what enables 5G's flexibility.
Tip: Learn the trio AMF (mobility), SMF (sessions), UPF (data). The UPF is the one packets actually flow through; AMF and SMF only orchestrate.
Go deeper:
5G — Core network architecture (Wikipedia) — the SBA section with the AMF/SMF/UPF table and how modular NFs replace the 4G EPC.