| 摘 要： |
As the need for limitless connectivity surges, non-terrestrial networks (NTN) will play a central role in fifth generation (5G) and beyond communications. The 3rd Generation Partnership Project (3GPP) defines NTN as networks, or segments of networks, using an airborne or space-borne vehicle as a relay node or base station. An NTN-enhanced cellular network supplements a conventional terrestrial cellular network. This article provides an overview of NTN-enhanced cellular networks with a particular focus on satellite-mobile direct communications. First, we review satellite system classifications such as Geostationary Orbit (GEO), Medium Earth Orbit (MEO), and Low Earth Orbit (LEO), spectrum usage, and key challenges of satellite communications. We then summarize recent 3GPP activities in NTN. In addition, we describe our recent proof-of-concept system involving a satellite channel emulator and modification of the 5G New Radio (NR) protocol stack to handle the challenge of long round-trip time - demonstrating the feasibility of NTN and the adoption of NTN-enhanced cellular networks in 5G and beyond communications. Finally, we highlight the main open issues and future research challenges of NTN-enhanced cellular networks.
随着对无限连接需求的不断增长，非地面网络（NTN）将在第五代（5G）及更高级别的通信中发挥核心作用。第三代合作伙伴计划（3GPP）将NTN定义为使用飞行器或航天器作为中继节点或基站的网络或网络部分。NTN增强型蜂窝网络是对传统地面蜂窝网络的补充。本文概述了NTN增强型蜂窝网络，重点聚焦于卫星-移动直接通信。首先，我们回顾卫星系统分类（如地球静止轨道、中地球轨道和低地球轨道）、频谱使用情况以及卫星通信面临的关键挑战。接着，总结了3GPP近期在NTN领域的相关工作。此外，我们介绍了近期开发的概念验证系统，该系统包括卫星信道模拟器以及对5G新无线电（NR）协议栈的修改，以应对长往返时延的挑战，从而证明了NTN的可行性，并展示了NTN增强型蜂窝网络在5G及未来通信中的应用前景。最后，我们重点阐述了增强型蜂窝网络（NTN）所面临的主要开放性问题及未来研究挑战。 |
京公网安备 11010202009788