In Release 17, 3GPP introduced adaptations and enhancements to the 5G new radio (NR) specification to support non-terrestrial networks (NTNs) operation. The main challenges were due to long propagation delays, especially in GEO deployments, and the movement of the satellites in LEO deployments. In this paper, we give an overview of the protocol adaptations to support NTNs. The main user plane protocol adaptations include changes to random access and hybrid automatic repeat request to due long propagation delays. The control plane protocol adaptations include a variety of mobility related enhancements for user equipment.

中文翻译：

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5G新无线电非地面网络的无线电接口协议和无线电资源管理程序

在第 17 版中，3GPP 对 5G 新无线电 (NR) 规范进行了调整和增强，以支持非地面网络 (NTN) 操作。主要挑战是传播延迟较长，尤其是在 GEO 部署中，以及卫星在 LEO 部署中的移动。在本文中，我们概述了支持 NTN 的协议改编。主要的用户平面协议调整包括对随机接入的更改和由于长传播延迟而导致的混合自动重复请求。控制平面协议适配包括针对用户设备的各种与移动性相关的增强。