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：为支持灵活且经济高效的网络密集化与部署，第三代合作伙伴计划（3GPP）近期已将集成接入与回传（IAB）作为第五代新空口（5G-NR）网络的一部分进行标准化。然而，当前标准化仅定义了地面领域的IAB，非地面网络（NTN）尚未纳入此类标准化工作。本文阐述了在NTN中应用IAB的动机，并讨论了5G-NR中IAB的3GPP规范与卫星无线电法规之间的兼容性问题。此外，我们明确了为实现支持NTN的IAB操作，需由3GPP和/或卫星运营商进行的必要适应性调整。针对低地球轨道（LEO）卫星支持的带内IAB操作，提供了一项案例研究，涵盖接入与回传间采用正交与非正交带宽分配、以及时分双工/频分双工（TDD/FDD）传输模式。数值结果证明了通过卫星实现IAB的可行性，并展示了FDD相较于TDD传输的优越性。同时表明，在无预编码的情况下，接入与回传间的非正交带宽分配会严重降低网络吞吐量。