In this work, we consider the deployment of reconfigurable intelligent surfaces (RISs) to extend the coverage of a millimeter-wave (mmWave) network in indoor dense spaces. We first integrate RIS into ray-tracing simulations to realistically capture the propagation characteristics, then formulate a non-convex optimization problem that minimizes the number of RISs under rate constraints. We propose a feasible point pursuit and successive convex approximation-based algorithm, which solves the problem by jointly selecting the RIS locations, optimizing the RIS phase-shifts, and allocating time resources to user equipments (UEs). The numerical results demonstrate substantial coverage extension by using at least four RISs, and a data rate of 130 Mbit/s is guaranteed for UEs in the considered area of an airplane cabin.

翻译：本文研究在室内密集空间中部署可重构智能表面(reconfigurable intelligent surfaces, RISs)以扩展毫米波(millimeter-wave, mmWave)网络覆盖范围的问题。我们首先将RIS集成到射线追踪仿真中，以真实捕获传播特性，随后构建一个在速率约束下最小化RIS数量的非凸优化问题。提出一种基于可行点追踪与逐次凸逼近的算法，通过联合选择RIS部署位置、优化RIS相位偏移以及为用户设备(user equipments, UEs)分配时间资源来求解该问题。数值结果表明，在飞机客舱场景下，使用至少四个RIS可实现显著的覆盖扩展，且能保障UE达到130 Mbit/s的数据速率。