Capacity Maximization for Active RIS Assisted Outdoor-to-Indoor Communication System

In this paper, we aim to implement outdoor-to-indoor communication with the aid of an active reconfigurable intelligent surface (active-RIS), where the active-RIS allows the incoming signal from an outdoor base station (BS) to pass through the surface and be received by indoor users (UEs) after shifting phase and magnifying amplitude. Then, the problem of joint beamforming optimization of the BS and active-ITS is investigated to maximize the system capacity. A computationally efficient algorithm is developed to solve it with suboptimal solutions. Simulations indicate the superiority of the active-RIS and the effectiveness of the proposed algorithm.