What is NSA NR?
NSA NR (Non-Standalone New Radio) is a 5G deployment option where the 5G NR radio operates under the control of the existing 4G LTE infrastructure. In NSA mode, the LTE eNB serves as the master node anchoring the control plane to the 4G Evolved Packet Core (EPC), while the NR en-gNB acts as a secondary node providing additional data throughput via 5G radio. NSA (specifically EN-DC, Option 3x) was the first 5G deployment option adopted commercially worldwide, enabling operators to launch 5G services quickly by leveraging their existing 4G core networks.
How Does NSA NR Work?
In NSA EN-DC, the UE maintains a dual connection — one to the LTE master eNB and one to the NR secondary en-gNB. The control plane (RRC) anchor remains on LTE, meaning the initial connection, mobility management, and security are handled by the eNB via the 4G EPC (MME/S-GW/P-GW). The NR en-gNB provides only user plane data transmission. Data can be split at the eNB (option 3), at the en-gNB (option 3a), or using dual bearer (option 3x). The UE combines data from both radio links using PDCP-level aggregation, achieving throughput that is the sum of LTE and NR contributions. NSA does not support 5G-specific core features like network slicing or SBA — these require SA deployment.
Use Cases
Initial 5G commercial launches (2019–2024), rapid 5G speed enhancement over existing 4G networks, gradual 5G spectrum deployment, eMBB service delivery using combined LTE+NR throughput, and stepping stone toward full 5G SA migration.
3GPP / Standards Reference
3GPP TS 37.340 (Multi-connectivity — EN-DC), 3GPP TS 38.300 (NR overall description), 3GPP TS 36.300 (E-UTRAN — EN-DC support)
Related Terms
SA | EN-DC | en-gNB | EPC | NSA
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This glossary entry is part of the 5GWorldPro Complete 5G Glossary. To go deeper into 5G architecture and technology, explore our 5G Training courses.
