The 5G Non-Terrestrial Network (NTN) integrates satellite and airborne platforms with terrestrial 5G networks to provide ubiquitous coverage.
The Next-Generation Radio Access Network (NG-RAN) architecture in 5G NTN can be designed to be transparent (i.e., with minimal on-board processing) to reduce payload complexity while ensuring seamless interoperability with terrestrial 5G systems. A transparent NTN payload acts as a relay, forwarding signals between User Equipment (UE) and ground stations without extensive onboard processing.
Key Features of Transparent 5G NTN NG-RAN:
- Low-Complexity Satellite Payload: The absence of on-board baseband processing reduces cost and power consumption.
- Ground-Based gNB Processing: All RAN functions (scheduling, HARQ, beamforming) are handled on the ground.
- Standardized Interfaces:
- F1 Interface between gNB-CU and gNB-DU.
- NG Interface between gNB and 5GC.
Note:
- The UE communicates over the air interface (modified for NTN delays) to the satellite, which does not decode or encode 5G signals; it forwards them transparently.
- The second architecture option is called “Regenerative NTN.” The significant difference from the transparent payload architecture is that the gNB functions are incorporated into the satellite itself.