| Feature | NSA 5G | SA 5G |
|---|---|---|
| Voice | VoLTE (4G) | VoNR (Native 5G) |
| Core Network | 4G EPC | 5G Core (5GC) |
| Latency | Higher (depends on 4G) | Ultra-low (~5-10ms) |
| Network Slicing | Not Supported | Supported (e.g., dedicated voice slices) |
5G NSA Architecture
Control Plane: Managed by 4G LTE (via the 4G Evolved Packet Core (EPC)).
User Plane: Uses 5G NR for high-speed data, but voice relies on 4G VoLTE.
Dual Connectivity (EN-DC): Your device connects both 4G and 5G simultaneously, but voice and data are split between two.
What happens during a voice call on NSA 5G?
- Voice Call Initiation:
- Your phone uses 4G LTE to set up the call via VoLTE(IMS core).
- The 5G NR connection is temporarily suspended or underutilized for the duration of the call.
- Data During the Call:
- If the carrier supports EN-DC (E-UTRA-NR Dual Connectivity):
- 5G NR continues handling data (e.g., browsing, streaming) while the voice call runs over 4G VoLTE.
- If EN-DC isn't supported:
- Data falls back to 4G LTE during the call (just like in pure 4G VoLTE).
- Call Termination:
After the call ends, your device re-establishes the 5G NR connection for data (if available).
5G SA Architecture
Key Architectural Differences:
Full 5G Core (5GC): SA uses the new 5G Core network (not 4G EPC) for both control and user planes.
No 4G Dependency: All functions (voice/data) run natively on 5G without LTE anchors.
Single RAN: Uses only 5G New Radio (NR) base stations (gNBs), not LTE eNBs.
Key Components
- AMF (Access & Mobility Management Function): Handles connection management
- SMF (Session Management Function): Manage user sessions.
- UPF (User Plane Function): Routes data traffic (It is the equivalent to 4G's PGW/SGW).
- UDM (Unified Data Management): Authentication / Authorization
- gNB: 5G base station
What happens during a voice call process (VoNR)?
- Call Setup: Uses Voice over NR (VoNR) through IMS core without 4G fallback.
- Data Continuity: Maintains 5G data connection simultaneously.
- No Session Suspension: Unlike NSA, SA maintains full 5G capabilities during calls.
SA Advantages:
- Ultra-low Latency (<;1ms theoretically)
- Network Slicing Capabilities
- True end-to-end 5G Security
- Massive IoT Support (mMTC [Massive Machine-Type Communications])
- Enhanced Mobile Broadband (eMBB)
Deployment Challenges:
- Requires complete 5G core deployment.
- Limited device ecosystem (though improving)
- Higher infrastructure costs