Innovative Multi-Layer Approaches for 6G Integrated Terrestrial And Non-Terrestrial Networks

This paper explores the integration of Terrestrial Networks and Non-Terrestrial Networks (T/NTNs) as a critical enabler for the 6th Generation (6G) of communication systems. Starting from the 3rd Generation Partnership Project (3GPP)specifications and roadmap, this article investigates cutting-edge aspects of architectural designs, advanced transmission techniques, and cross-domain management strategies. In particular,in order to address challenges in seamless connectivity and optimized resource utilization, the proposed multi-layer approachcombines terrestrial, aerial, and satellite components for improved coverage, scalability, and adaptability. Key and innovativecontributions include modular waveform designs, efficient man-agement of free-space optical links, and a comprehensive NTN framework.