1. What is NTN?
Non-Terrestrial Networks (NTN) use satellites, drones, or high-altitude platforms to provide wireless coverage where ground-based networks can't reach ā oceans, polar regions, rural areas, and disaster zones.
3GPP Release 17 formally integrated NTN into the 5G NR standard.
2. Types of NTN
| Type | Altitude | Example | Latency |
|---|---|---|---|
| GEO Satellite | ~35,786 km | Intelsat | ~600 ms |
| MEO Satellite | 2,000ā20,000 km | O3b (SES) | ~130 ms |
| LEO Satellite | 300ā2,000 km | Starlink, OneWeb | ~20 ms |
| HAP | 17ā22 km (strato.) | HAPSMobile | <5 ms |
| UAV / Drone | <1 km | Emergency coverage | <1 ms |
3. NTN + 5G/6G Integration
Key adaptations required for 5G NR over satellite:
- Timing Advance (TA) ā extended TA for propagation delays up to 270 ms (GEO)
- Frequency compensation ā Doppler shifts of tens of kHz for LEO satellites
- HARQ adaptation ā Longer HARQ round-trip times require HARQ disabling or process expansion
- Feeder link vs service link ā Gateway ā satellite vs satellite ā UE architecture