NSA
Non-Standalone: a 5G deployment option where the NR radio connects to the existing 4G EPC core network, using LTE as the anchor for control-plane signaling (Option 3/3a/3x).
NSA is how almost every operator switched on 5G first, because it's cheap and fast: bolt NR radios onto the existing LTE network and reuse the 4G EPC core. The LTE eNB stays the anchor — it handles all the control-plane signalling and mobility — while the NR carrier is added as a secondary leg for extra user-plane throughput. The UE is connected to both at once, which is EN-DC.
The trade is that you don't get the genuinely new 5G capabilities. Network slicing, native URLLC, and the service-based 5GC architecture all live in Standalone; NSA gives you 5G speeds layered on a 4G control plane. The "Option 3" family describes where user-plane traffic splits — Option 3 splits at the eNB, 3a routes the NR bearer straight to the EPC, and 3x (the most deployed) splits at the gNB. For subscribers the upshot is real: faster data, but the latency and architecture benefits stay capped until the operator moves to SA.
Frequently asked questions
- What's the difference between NSA and SA 5G?
- NSA reuses the 4G EPC core and an LTE anchor for control signalling, adding NR purely for extra speed — the device stays attached to both 4G and 5G. SA connects NR directly to the 5G Core with no LTE dependency, which is what makes network slicing, ultra-low-latency services, and the full service-based architecture possible. NSA was the quick way to launch; SA is where the distinctive 5G features actually live.
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