5G • RAN

NSA vs SA

Non-Standalone (Option 3x) vs Standalone (Option 2)

The two major deployment modes of 5G: NSA leverages existing 4G LTE core (EPC), while SA uses a dedicated 5G Core (5GC) for full native 5G capabilities.

Technical Explanation

• Non-Standalone (NSA Option 3x): The 5G gNodeB connects to the existing 4G EPC (MME/SGW) alongside the 4G eNodeB. The UE anchors its control plane in 4G (LTE RRC) while aggregating 5G NR carriers for high-speed user plane data via Dual Connectivity (EN-DC). This enabled rapid 5G rollout without replacing core infrastructure. • Standalone (SA Option 2): The 5G gNodeB connects directly to the cloud-native 5G Core Network (5GC). Both control plane and user plane run exclusively over 5G NR. SA unlocks true end-to-end network slicing, ultra-low URLLC latency, edge computing, Voice over NR (VoNR), and service-based operations.

Key Functions

  • NSA allows fast time-to-market using 4G EPC core assets
  • SA enables native network slicing, microservices SBA, and sub-millisecond URLLC
  • NSA relies on EN-DC (E-UTRA - NR Dual Connectivity)
  • SA eliminates 4G anchor dependencies and enables VoNR instead of EPS Fallback
Specifications
3GPP TR 38.801, TS 23.501, TS 37.340
Interfaces
NSA: S1-C, S1-U, X2-C, X2-U | SA: N1, N2, N3, Xn

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