As 5th generation (5G) networks continue to evolve, there is a growing interest toward the integration of Terrestrial Networks (TNs) and Non-Terrestrial Networks (NTNs). Specifically, NTNs leverage space/air base stations such as satellites, High Altitude Platforms (HAPs), and Unmanned Aerial Vehicles (UAVs) for expanding wireless coverage to underserved rural/remote areas, supporting emergency communications, and offloading traffic in highly congested urban environments. In this paper we focus on the 3GPP 5G NR-NTN standard in the context of satellite communication networks, and highlight critical challenges that must be addressed for proper full-stack protocol design, with considerations related to the PHY, MAC, and higher layers. We also present simulation results in ns-3 to demonstrate the impact of some of these challenges on the network, as an initial step toward more advanced standardization activities on 3GPP 5G NR-NTN.

翻译：随着第五代（5G）网络的持续演进，地面网络（TNs）与非地面网络（NTNs）的融合日益受到关注。具体而言，NTNs利用卫星、高空平台（HAPs）和无人机（UAVs）等空间/空中基站，将无线覆盖扩展至服务不足的农村/偏远地区，支持应急通信，并在高度拥堵的城市环境中分流业务。本文聚焦于卫星通信网络背景下的3GPP 5G NR-NTN标准，并着重指出在全栈协议设计中必须解决的关键挑战，这些挑战涉及物理层（PHY）、媒体接入控制层（MAC）及更高层。我们还通过ns-3仿真展示了其中部分挑战对网络的影响，以此作为推进3GPP 5G NR-NTN更高级标准化活动的初步探索。