Non-Terrestrial Networking for 6G: Evolution, Opportunities, and Future Directions

TL;DR

This paper surveys Non-Terrestrial Networks (NTN) as a key pillar of 6G, focusing on LEO-driven space Internet capabilities, and identifies core challenges in radio resource management, mobility management, and onboard traffic scheduling that affect QoS. It synthesizes advances in CSI estimation, beamforming, NTN mobility management, and SD-NTN traffic scheduling, and introduces GenAI-enabled satellite beamforming with predictive CSI and proactive resource management. The work highlights the potential of GenAI for CSI generation and predictive beamforming, and discusses mobility enhancements (seamless handovers, pre-configured sequences, TN-NTN integration) and SD-NTN network slicing as essential enablers for reliable, flexible service delivery. It concludes with open problems and future directions, including interference management, ISAC in NTNs, TN-NTN unification, and secure, resilient network slicing, underscoring the practical impact of space Internet deployments for global connectivity.

Abstract

From 5G onwards, Non-Terrestrial Networks (NTNs) have emerged as a key component of future network architectures. Leveraging Low Earth Orbit (LEO) satellite constellations, NTNs are capable of building a space Internet and present a paradigm shift in delivering mobile services to even the most remote regions on Earth. However, the extensive coverage and rapid movement of LEO satellites pose unique challenges for NTN networking, including user equipment (UE) access and inter-satellite delivery, which directly impact the quality of service (QoS) and data transmission continuity. This paper offers an in-depth review of advanced NTN management technologies in the context of 6G evolution, focusing on radio resource management, mobility management, and dynamic network slicing. Building on this foundation and considering the latest trends in NTN development, we then present some innovative perspectives to emerging challenges in satellite beamforming, handover mechanisms, and inter-satellite transmissions. Lastly, we identify open research issues and propose future directions aimed at advancing satellite Internet deployment and enhancing NTN performance.

Figures (7)

• Figure 1: NTN diverse networking scenarios and comparison with TN.
• Figure 2: Structure of GenAI-empowered CSI prediction.
• Figure 3: Predictive Beamforming Protocol.
• Figure 4: Spatial-temporal signal variation differences between TN and NTN.
• Figure 5: UE connectivity and BS signaling in integrated TN-NTN.