Non-terrestrial Networks for 5G-Advanced

- Overview 

5G-Advanced Non-Terrestrial Networks (NTN) integrate spaceborne (LEO, MEO, GEO satellites) and airborne (HAPS, UAVs) platforms into the 3GPP ecosystem to provide ubiquitous coverage. 

Standardized in Releases 17 and 18, NTN complements terrestrial networks, offering direct-to-device connectivity, global IoT, and improved service continuity for remote areas. 

NTN is critical for bridging the digital divide, with 3GPP-standardized solutions ensuring seamless interoperability between satellite and ground-based infrastructure.

1. Key aspects of 5G-Advanced NTN include:

• Technology & Architecture: NTN leverages 5G New Radio (NR) protocols to connect User Equipment (UE) directly to satellites, supporting both bent-pipe and regenerative (on-board processing) architectures.

2. Key Use Cases:

• Direct-to-Cellular: Enables smartphones to connect directly to satellites for messaging and emergency services.
• IoT & Agriculture: Facilitates low-power connectivity for remote monitoring.
• Mobility: Provides high-speed connectivity to aircraft, ships, and trains.
• Public Safety: Ensures communication links during disasters when terrestrial infrastructure fails.

3. 5G-Advanced Improvements (Rel-18+): Enhanced mobility, optimized handover between satellite and terrestrial networks, better channel models, and improved support for higher frequencies. 

4. Technical Challenges & Solutions: Addressing significant Doppler shifts and high propagation delays caused by LEO/GEO motion, utilizing advanced timing advance procedures.