Leveraging non-terrestrial platforms in 6G networks holds immense significance as it opens up opportunities to expand network coverage, enhance connectivity, and support a wide range of innovative applications, including global-scale Internet of Things and ultra-high-definition content delivery. To accomplish the seamless integration between terrestrial and non-terrestrial networks, substantial changes in radio access network (RAN) architecture are required. These changes involve the development of new RAN solutions that can efficiently manage the diverse characteristics of both terrestrial and non-terrestrial components, ensuring smooth handovers, resource allocation, and quality of service across the integrated network ecosystem. Additionally, the establishment of robust interconnection and communication protocols between terrestrial and non-terrestrial elements will be pivotal to utilize the full potential of 6G technology. Additionally, innovative approaches have been introduced to split the functionalities within the RAN into centralized and distributed domains. These novel paradigms are designed to enhance RAN's flexibility while simultaneously lowering the costs associated with infrastructure deployment, all while ensuring that the quality of service for end-users remains unaffected. In this work, we provide an extensive examination of various Non-Terrestrial Networks (NTN) architectures and the necessary adaptations required on the existing 5G RAN architecture to align with the distinct attributes of NTN. Of particular significance, we emphasize the crucial RAN functional split choices essential for the seamless integration of terrestrial and non-terrestrial components within advanced 6G networks.

翻译：在6G网络中利用非地面平台具有重要意义，这为扩展网络覆盖范围、增强连接性以及支持包括全球物联网和超高清内容分发在内的广泛创新应用开辟了机遇。为实现地面与非地面网络的无缝集成，需要在无线接入网络（RAN）架构上进行重大变革。这些变革涉及开发新的RAN解决方案，以高效管理地面与非地面组件的多样特性，确保在集成网络生态系统中实现平滑切换、资源分配和服务质量保障。此外，建立地面与非地面元素之间的鲁棒互连和通信协议，对于充分利用6G技术潜力至关重要。同时，业界已引入创新方法将RAN内的功能拆分为集中域和分布式域。这些新型范式旨在增强RAN的灵活性，同时降低基础设施部署的相关成本，并确保最终用户的服务质量不受影响。本文广泛研究了多种非地面网络（NTN）架构，以及为适应NTN独特属性而对现有5G RAN架构进行的必要调整。特别值得关注的是，我们强调了在先进6G网络中实现地面与非地面组件无缝集成所必需的关键RAN功能拆分选择。