Non-terrestrial Networks for 5G and Beyond

- Overview

Non-Terrestrial Networks (NTN) for 5G and beyond are wireless communication systems using satellites (LEO, MEO, GEO) or high-altitude platforms (HAPS, drones) to provide 3GPP-standardized coverage from above the Earth's surface.

NTNs deliver ubiquitous,, high-speed 5G connectivity to remote areas, maritime, aerial, and IoT devices, ensuring service continuity where terrestrial networks are unfeasible. 

NTN technology is considered critical for bridging the digital divide and enabling a truly global, 3D, and resilient communications infrastructure.

1. Key aspects of NTN for 5G and beyond include:

• Components and Orbits: NTNs utilize Low Earth Orbit (LEO) for low latency, Medium Earth Orbit (MEO) for regional coverage, and Geostationary Earth Orbit (GEO) for broad coverage. They also employ High Altitude Platforms (HAPS) such as drones and balloons.

2. Key Use Cases:

• Ubiquitous Coverage: Providing 5G connectivity to remote, rural, or maritime locations.
• Direct-to-Device (D2D): 3GPP Release 17+ enables standard smartphones to connect directly to satellites.
• Internet of Things (IoT): Supporting massive IoT for logistics and remote tracking.
• Disaster Recovery: Offering resilient communication networks when terrestrial infrastructure is destroyed.

3. Integration with 5G NR: NTN NR (New Radio) allows seamless integration, enabling smooth mobility between cellular and satellite networks. 

4. Future (Beyond 5G/6G): Future developments aim to integrate low-altitude platforms (LAP) and drones more tightly, enhancing coverage and supporting AI-driven, 3D network architectures.

5. Challenges: Key challenges include high deployment costs, signal propagation delays, and the need for spectrum coordination with terrestrial networks.

- Key Technologies and Components of 5G NTN

5G Non-Terrestrial Networks (NTNs) are critical for providing ubiquitous, resilient, and high-speed connectivity by integrating satellites (LEO/GEO) and HAPS into the 3GPP 5G ecosystem. 

They offer essential coverage for remote areas, disaster recovery, and IoT, while allowing seamless handovers from terrestrial networks, thus extending coverage to the entire globe. 

(A) Key Aspects for 5G NTN Importance: 

• Ubiquitous Coverage and Capacity: NTNs eliminate dead spots by providing coverage in remote areas, oceans, and high altitudes, while supporting massive IoT and broadband services.
• Network Resilience and Backup: They provide critical communication links during natural disasters or network outages where terrestrial infrastructure is destroyed.
• Seamless Integration (3GPP Rel-17): By using standardized 5G protocols, NTNs allow user devices to switch between terrestrial and satellite networks without service interruption.
• Enabling New Use Cases: They support advanced applications such as autonomous driving, maritime and aviation communications, and global asset tracking.
• Economic Scalability: They provide a cost-effective alternative to laying ground infrastructure in difficult terrains.

2. Key Technologies and Components:

• Satellite Orbits: Low Earth Orbit (LEO) satellites (10s of Gbps capacity) and Geostationary (GEO) satellites are central to providing coverage.
• HAPS (High-Altitude Platform Stations): Aerial platforms providing intermediate coverage between terrestrial and satellite.
• IoT and Direct-to-Device (D2D): Enables direct connection of standard devices to satellites, expanding coverage for NB-IoT and eMTC applications.

3. Key Challenges Addressed:

• Doppler Shift & Propagation Delay: Samsung and other vendors are developing techniques to mitigate signal distortions caused by fast-moving LEO satellites and high latency.
• Standardization: 3GPP Release 17 ensures a common radio interface for seamless integration with existing 5G networks.

- The Strategic Role of NTNs in 5G and Beyond

Non-Terrestrial Networks (NTNs), incorporating satellites (LEO, GEO) and aerial vehicles (UAVs), are crucial for 5G and 6G to achieve ubiquitous, resilient, and global connectivity. 

They bridge the digital divide in remote areas, offer critical disaster recovery, and enable IoT applications by providing seamless, high-speed coverage where terrestrial infrastructure is impossible or impractical. 

Key enhancements, such as handling Doppler shifts and long signal travel times (propagation delays), allow NTN to function efficiently with smartphones and other devices, overcoming traditional limitations of satellite communications.

1. Key strategic roles of 5G NTN include:

• Universal Coverage and Connectivity: NTNs bridge the digital divide by delivering broadband to underserved, maritime, aviation, and remote areas, expanding the addressable market for network operators.
• Network Resilience and Safety: They provide essential backup for terrestrial networks, ensuring continuity during natural disasters, infrastructure failures, or in high-risk zones.
• IoT and M2M Support: NTNs enable massive Internet of Things (IoT) and Machine-to-Machine (M2M) deployments for agriculture, asset tracking, and transportation, requiring low-latency, reliable, and wide-area coverage.
• 3GPP Integration and Evolution: Standardized via 3GPP Release 17 and beyond, 5G NTN integrates with terrestrial systems to offer seamless, standards-based, and secure connectivity.
• 6G Foundation: As an integral part of 6G, NTNs are essential for the future of mobile communications, ensuring that 5G Advanced and 6G networks are truly global and ubiquitous.

- The Role of Satellites in 5G Networks

Satellites are crucial for evolving 5G into a "network of networks," providing essential, ubiquitous coverage, backhaul support, and resilience beyond the limitations of terrestrial fiber. 

Integrating space-based assets enables seamless connectivity for IoT, vehicles, and remote areas, while offloading congestion in urban centers. 

This integration of satellite with 5G, often referred to as non-terrestrial networks (NTN), ensures that 5G’s promise of high-speed, low-latency connectivity reaches every corner of the globe.

1. Key Roles of Satellites in 5G and Beyond:

• Ubiquitous Coverage & Rural Connectivity: Satellites overcome the economic and physical limitations of laying fiber, extending 5G service to rural, maritime, and aerial locations.
• Enhanced Network Resilience & Backup: Satellite links offer critical redundancy during natural disasters or network failures, maintaining connectivity when terrestrial infrastructure is destroyed.
• Backhaul and Data Offloading: Satellites manage high-volume traffic and congestion by providing high-speed backhaul, moving data between the radio access network (RAN) and core network, especially in underserved areas.
• Support for Moving Platforms: Seamless handovers enable high-speed connectivity for planes, ships, and trains, ensuring uninterrupted service.
• IoT and Broadcasting: Satellite multicast capabilities allow efficient, simultaneous content distribution to numerous devices, supporting massive Machine-Type Communications (mMTC) and broadcasting.

- Satellite-based Non-Terrestrial Networks (NTN)

Satellite-based Non-Terrestrial Networks (NTN) in 5G, standardized by 3GPP (Release 17+), integrate LEO, MEO, and GEO satellites or HAPs to deliver ubiquitous connectivity, filling coverage gaps in remote, maritime, and aerospace locations. By using 5G NR, they offer direct-to-device, IoT, and high-speed communication. 

These "cell towers in space" enhance 5G service with disaster resilience, seamless roaming, and support for advanced, wide-area use cases. 

1. Key Aspects of 5G NTN Implementation: 

• Ubiquitous Coverage: Extends 5G connectivity to areas where terrestrial infrastructure is not feasible, such as oceans, mountains, and remote regions.
• Direct-to-Device (D2D): Enables standard mobile devices to connect directly to satellites, which is a major, fast-growing trend in 5G standardization.
• Disaster Recovery: Provides crucial communication, offering resilient and rapid deployment for emergency services during terrestrial infrastructure damage.
• IoT & Service Continuity: Supports massive machine-type communication (IoT) for tracking and monitoring, as well as seamless roaming between satellite and terrestrial networks. 
• Key Architectures: Utilizes Low Earth Orbit (LEO) for lower latency, Geostationary Earth Orbit (GEO) for wider, stable coverage, and High Altitude Platforms (HAPs). 
• Technical Challenges: Addresses significant propagation delays, high Doppler shifts, and beam management, requiring advanced compensation mechanisms in the 5G standard.

2. Main Reasons for 5G NTN Adoption:

• Enhanced Reliability: Ensures continuous, global service for mission-critical applications.
• Market Growth: Driven by significant investment in LEO satellites and the need for expanding 5G to 100% of the Earth's surface.
• Cost-Effective Expansion: Provides a more viable alternative to expanding ground-based infrastructure in sparsely populated areas.

- The Path to 5G-Advanced and 6G Non-Terrestrial Network 

The evolution of Non-Terrestrial Networks (NTNs) from 5G to 6G aims to create a "3D" wireless architecture by integrating satellite, airborne, and terrestrial nodes to provide ubiquitous global connectivity. 

1. System Architecture & Technologies:

• 3D Network Architecture: Integration of LEO (Low Earth Orbit), MEO (Medium Earth Orbit), and GEO (Geostationary) satellites with High-Altitude Platform Systems (HAPS) and Unmanned Aerial Vehicles (UAVs).
• AI-Native Integration: Use of Artificial Intelligence and Machine Learning for autonomous resource management, dynamic beam steering, and handover optimization between satellite and terrestrial cells.
• Spectrum & Hardware: Leveraging higher frequency bands (including mmWave and eventually Terahertz) and technologies like Reconfigurable Intelligent Surfaces (RIS) to overcome signal attenuation.
• Direct-to-Device (D2D): Standardizing direct satellite access for unmodified smartphones to enable seamless global roaming.

2. Key Services:

• Ubiquitous Connectivity: Eliminating "dead zones" in remote, maritime, and polar regions.
• Enhanced Positioning: Achieving <10 cm high-precision positioning by fusing satellite and terrestrial signals.
• Emergency & IoT: Support for massive IoT (mIoT) and mission-critical services like disaster recovery and E911.
• Immersive & Real-time: Enabling 1 Tbps peak data rates and sub-millisecond latency for digital twins, holographic communications, and autonomous mobility.

3. Standardization Roadmap (3GPP): 

The transition follows a phased release approach to ensure backward compatibility and gradual enhancement:

• Release 17 (Completed): First dedicated NTN specifications; focused on transparent satellite payloads and basic IoT support.
• Release 18 & 19 (5G-Advanced): Introduction of regenerative payloads (onboard processing) and enhanced mobility management.
• Release 20 & 21 (The Bridge to 6G): The "inflection point" where 6G fundamentals are shaped alongside final 5G-A features.
• IMT-2030 (6G): Full commercial rollout expected around 2030, targeting complete convergence of terrestrial and non-terrestrial domains.