To allow flexible and cost-efficient network densification and deployment, the integrated access and backhaul (IAB) was recently standardized by the third generation partnership project (3GPP) as part of the fifth-generation new radio (5G-NR) networks. However, the current standardization only defines the IAB for the terrestrial domain, while non-terrestrial networks (NTNs) are yet to be considered for such standardization efforts. In this work, we motivate the use of IAB in NTNs, and we discuss the compatibility issues between the 3GPP specifications on IAB in 5G-NR and the satellite radio regulations. In addition, we identify the required adaptation from the 3GPP and/or satellite operators for realizing an NTN-enabled IAB operation. A case study is provided for a low earth orbit (LEO) satellite-enabled in-band IAB operation with orthogonal and non-orthogonal bandwidth allocation between access and backhauling, and under both time- and frequency-division duplex (TDD/FDD) transmission modes. Numerical results demonstrate the feasibility of IAB through satellites, and illustrate the superiority of FDD over TDD transmission. It is also shown that in the absence of precoding, non-orthogonal bandwidth allocation between the access and the backhaul can largely degrades the network throughput.

翻译：为实现灵活且经济高效的网络密集化部署，第三代合作伙伴计划（3GPP）近期将集成接入与回传（IAB）技术纳入第五代新空口（5G-NR）网络标准。然而，当前标准化工作仅定义了地面域IAB，非地面网络（NTN）尚未纳入此类标准化考量。本研究旨在论证NTN中部署IAB的可行性，并探讨3GPP关于5G-NR IAB规范与卫星无线电法规之间的兼容性问题。此外，我们明确了实现支持NTN的IAB运行所需对3GPP和/或卫星运营商进行的适应性调整。通过低地球轨道（LEO）卫星支持的同频IAB案例研究，分析了接入链路与回传链路在正交与非正交带宽分配、时分/频分双工（TDD/FDD）传输模式下的性能表现。数值结果验证了卫星IAB的可行性，并表明FDD传输优于TDD。研究同时显示，在无预编码条件下，接入与回传链路的非正交带宽分配会显著降低网络吞吐量。