论文标题
被动RIS与Hybrid RIS：通道估计的比较研究
Passive RIS vs.Hybrid RIS: A Comparative Study on Channel Estimation
论文作者
论文摘要
当收发器之间的直接通道被阻断时，可重构智能表面（RIS）在保持毫米波（MMWave）MIMO系统中的连通性中起着重要作用。但是，很难获取通道状态信息（CSI），这对于在收发器中设计RIS相位控制矩阵和波束成形向量至关重要。在本文中，我们比较了纯粹的被动和混合体系结构的通道估计（CE）性能（CE）性能（CE）。 CE是通过原子规范最小化（ANM）完成的。对于纯粹的被动RI，我们遵循两阶段的程序来依次估计通道参数，而对于混合RIS，我们根据主动RIS元素的观察值估算了RIS处的单个通道，假设上行链路链接和下链路链接训练。模拟结果表明，与在相同的训练开销下的混合RI相比，纯粹的被动RI带来了更好的CE和SE性能。我们进一步考虑了混合动力的不同设置，并研究了其中的权衡。
The reconfigurable intelligent surface (RIS) plays an important role in maintaining the connectivity in millimeter wave (mmWave) MIMO systems when the direct channel between the transceivers is blocked. However, it is difficult to acquire the channel state information (CSI), which is essential for the design of RIS phase control matrix and beamforming vectors at the transceivers. In this paper, we compare the channel estimation (CE) performance and achieved spectral efficiency (SE) of the purely passive and hybrid RIS architectures. CE is done via atomic norm minimization (ANM). For the purely passive RIS, we follow a two-stage procedure to sequentially estimate the channel parameters, while for the hybrid RIS we estimate the individual channels at the RIS based on the observations from active RIS elements assuming alternating uplink and downlink training. The simulation results show that the purely passive RIS brings better CE and SE performance compared to the hybrid RIS under the same training overhead. We further consider different setups for the hybrid RIS and study the tradeoffs among them.
