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：可重构智能表面（RIS）已成为提升无线网络容量和扩展覆盖范围的一项有前景技术。本研究考虑RIS辅助的毫米波（mmWave）多输入多输出（MIMO）通信，其中由于信道的高维特性，获取精确的信道状态信息面临挑战。为充分利用信道结构，我们将信道估计问题表述为分层结构矩阵恢复问题，并设计了一种低复杂度消息传递算法进行求解。仿真结果表明，所提算法具有优越性，且其性能接近理论最优界。