Drones are envisaged as an important part of the future 6G systems. With the possibility of their fast deployment they provide additional connectivity options in form of a hotspot. However, typically in such a use case they require provisioning of a wireless backhaul link to facilitate their proper operation, which might be a challenging task in urban environment. One of the possible ways to connect such nodes is to use the integrate access and backhaul (IAB) approach, where part of the spectrum dedicated for user access at the base station is used for wireless backhauling. Thus, in this work we consider the problem of establishing a multi-hop wireless backhaul link following the IAB concept, with the aid of drone relay stations (DRSs) and reconfigurable intelligent surfaces (RISs). We formulate the problem of coverage improvement with fixed number of relays assuming certain throughput requirements on the backhaul. We show with simulations that the use of RISs allows for improvement of coverage in such a scenario or reduction in the number of involved nodes to provide the required backhaul.

翻译：无人机被设想为未来6G系统的重要组成部分。凭借快速部署的可能性，它们能够以热点形式提供额外的连接选项。然而，在此类典型用例中，无人机通常需要配置无线回传链路以保障其正常运行，这在城市环境下可能是一项具有挑战性的任务。连接此类节点的可行方式之一是采用集成接入与回传（IAB）方法，即将基站中部分专用于用户接入的频谱用于无线回传。因此，本文基于IAB概念，研究了在无人机中继站（DRS）与可重构智能表面（RIS）辅助下建立多跳无线回传链路的问题。我们针对固定数量中继站且满足特定回传吞吐量要求的场景，构建了覆盖增强问题模型。仿真结果表明，RIS的引入能够在此类场景中提升覆盖性能，或减少提供所需回传链路所涉及的节点数量。