Reconfigurable intelligent surface (RIS) has emerged as a promising technology for improving capacity and extending coverage of wireless networks. In this work, we consider RIS-aided millimeter wave (mmWave) multiple-input and multiple-output (MIMO) communications, where acquiring accurate channel state information is challenging due to the high dimensionality of channels. To fully exploit the structures of the channels, we formulate the channel estimation as a hierarchically structured matrix recovery problem, and design a low-complexity message passing algorithm to solve it. Simulation results demonstrate the superiority of the proposed algorithm and its performance close to the oracle bound.

翻译：摘要：随着可重构智能表面（RIS）成为改善无线网络容量和延伸覆盖范围的一种有前途的技术，我们考虑利用RIS辅助的毫米波（mmWave）多输入多输出（MIMO）通信，由于信道高维度性的缘故，准确地获得信道状态信息具有挑战性。为了充分利用信道结构，我们将信道估计问题形式化为分层结构矩阵恢复问题，并设计了一种低复杂度的消息传递算法来解决。仿真结果表明，所提出的算法具有卓越的优势，其性能接近于优化解的理论上限。