gNB

gNB, short for gNodeB, is the base station in 5G New Radio (NR) networks. It evolved from the LTE eNodeB and serves as the radio access interface between user equipment and the 5G core network. A gNB handles radio resource management, scheduling, and link adaptation, and may implement features such as beamforming, massive MIMO, carrier aggregation, and multi-TRP operation to support high data rates and low latency.

Architecture and interfaces: A gNB can be deployed as a single unit or functionally split into a Central Unit (CU) and a Distributed Unit (DU). The DU handles real-time radio signal processing and scheduling, while one or more CUs manage control and non-real-time tasks. The interface between CU and DU is the F1, with F1-C for control-plane traffic and F1-U for user-plane traffic. The radio unit portion communicates with user equipment via the NR air interface. The gNB can scale with multiple DUs and radio frequency front-ends to cover diverse deployment scenarios.

Connectivity to the core network: The gNB connects to the 5G Core (5GC) over the NG interface, which consists of NG-C for control-plane signaling and NG-U for user-plane traffic. The 5GC hosts core functions such as the Access and Mobility Function (AMF), Session Management Function (SMF), and User Plane Function (UPF), which manage mobility, session establishment, and data routing. This arrangement enables flexible deployment across different network architectures.

Deployment modes: Standalone (SA) deployments use the 5G Core as the control and user plane anchor. Non-standalone (NSA) deployments integrate NR radio access with an existing LTE network, providing initial 5G coverage while gradual introduction of the 5G core occurs. gNBs support a range of services, including enhanced mobile broadband, ultra-reliable low-latency communications, and massive machine-type communications.