While 5G networks are already being deployed for commercial applications, Academia and industry are focusing their effort on the development and standardization of the next generations of mobile networks, i.e., 5G-Advance and 6G. Beyond 5G networks will revolutionize communications systems providing seamless connectivity, both in time and in space, to a unique ecosystem consisting of the convergence of the digital, physical, and human domains. In this scenario, NonTerrestrial Networks (NTN) will play a crucial role by providing ubiquitous, secure, and resilient infrastructure fully integrated into the overall system. The additional network complexity introduced by the third dimension of the architecture requires the interoperability of different network elements, enabled by the disaggregation and virtualization of network components, their interconnection by standard interfaces and orchestration by data-driven network artificial intelligence. The disaggregation paradigm foresees the division of the radio access network in different virtualized block of functions, introducing the concept of functional split. Wisely selecting the RAN functional split is possible to better exploit the system resources, obtaining costs saving, and to increase the system performances. In this paper, we firstly provide a discussion of the current 6G NTN development in terms of architectural solutions and then, we thoroughly analyze the impact of the typical NTN channel impairments on the available functional splits. Finally, the benefits of introducing the dynamic optimization of the functional split in NTN are analyzed, together with the foreseen challenges.

翻译：尽管5G网络已在商业应用中部署，学术界和工业界正致力于下一代移动网络（即5G-Advanced和6G）的研发与标准化。超越5G的网络将通过融合数字、物理和人类领域，构建一个独特的生态系统，实现时空无缝连接，从而彻底改变通信系统。在此背景下，非地面网络（NTN）将发挥关键作用，提供完全集成于整体系统的泛在、安全且弹性可靠的网络基础设施。由架构中第三维度引入的额外网络复杂性，要求不同网元之间实现互操作性，这需要通过网络组件的解耦与虚拟化、标准化接口的互联以及数据驱动的网络人工智能编排来实现。解耦范式预示将无线接入网络划分为多个虚拟化功能模块，从而引入功能切分概念。合理选择RAN功能切分可优化系统资源利用、实现成本节约并提升系统性能。本文首先探讨当前6G NTN在架构方案方面的发展，随后深入分析典型NTN信道损伤对现有功能切分的影响，最后评估在NTN中引入功能切分动态优化的优势及所面临的挑战。