The concept of reconfigurable intelligent surface (RIS) has been proposed to
change the propagation of electromagnetic waves, e.g., reflection, diffraction,
and refraction. To accomplish this goal, the phase values of the discrete RIS
units need to be optimized. In this paper, we consider RIS-aided
millimeter-wave (mmWave) multiple-input multiple-output (MIMO) systems for both
accurate positioning and high data-rate transmission. We propose an adaptive
phase shifter design based on hierarchical codebooks and feedback from the
mobile station (MS). The benefit of the scheme lies in that the RIS does not
require deployment of any active sensors and baseband processing units. During
the update process of phase shifters, the combining vector at the MS is also
sequentially refined. Simulation results show the performance improvement of
the proposed algorithm over the random design scheme, in terms of both
positioning accuracy and data rate. Moreover, the performance converges to
exhaustive search scheme even in the low signal-to-noise ratio regime.

本文提出一种自适应相移器设计方案，采用 RIS 辅助毫米波 MIMO 系统进行准确定位和高速数据传输，使用基于分层码本和来自移动站的反馈的算法对离散 RIS 单元的相位值进行优化，其性能优于随机设计方案，且在低信噪比情况下性能收敛于穷尽搜索方案。