gNBs

gNB stands for next generation Node B and refers to the 5G NR base station in the 5G radio access network. It serves as the radio interface between user equipment (UE) and the 5G core network, delivering higher data rates, lower latency, and support for new use cases compared with previous generations. In standalone deployments, the gNB connects directly to the 5G core network. In non-standalone deployments, it operates with a 4G core and leverages existing control plane functions while providing NR access.

Architecture and deployment models

A gNB can be deployed as a single node or as a split architecture consisting of a Central Unit (CU) and Distributed Unit (DU), often with a separate Radio Unit (RU). The CU handles higher-layer control functions, while the DU manages lower-layer data processing (MAC/RLC/RLC) and scheduling. The F1 interface links the CU and DU (and RU in some configurations) and can carry control and user plane traffic. gNBs support advanced radio features such as beamforming and Massive MIMO, and can be deployed to serve multiple frequency ranges (FR1 and FR2) and support carrier aggregation and multi-beam operation.

Interfaces and core connectivity

The gNB connects to the 5G core network via NG interfaces: NG-C for control plane signaling with the Access and Mobility Function (AMF) and NG-U for user-plane data with the User Plane Function (UPF). For coordination with other base stations, gNBs use the Xn interface. In non-standalone deployments, the gNB may interwork with a 4G core for legacy mobility and signaling via established NSA architectures such as EN-DC.

Functions

Key responsibilities include radio resource control, scheduling, paging, mobility management, and security. gNBs implement the RAN stack (RRC, PDCP, RLC, MAC, physical layer) and enforce QoS, handovers, and slicing requirements, enabling high-capacity, low-latency connections for mobile broadband, IoT, and emerging enterprise services.