Channel Estimation for RIS-Aided Multiuser Millimeter-Wave Systems
Channel Estimation for RIS-Aided Multiuser Millimeter-Wave Systems
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DOI：
10.1109/tsp.2022.3158024
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发表时间：
2022-01-01
影响因子：
5.4
通讯作者：
Swindlehurst, A. Lee
中科院分区：
文献类型：
--
作者：
Zhou, Gui;Pan, Cunhua;Swindlehurst, A. Lee
可重构智能表面（RIS）是一种很有前途的装置，它可以通过调整反射元件的相移来重构电磁传播环境。然而，由于RIS的无源特性和大量的反射元件，RIS辅助的多用户多输入单输出（MU-MISO）无线通信系统中的信道估计是具有挑战性的，这可能导致高信道估计开销。为了解决这个问题，我们提出了一种新的级联信道估计策略，通过利用毫米波MISO系统中多用户级联信道的稀疏性和相关性，具有低导频开销。基于BS、RIS和用户的物理位置在多个连续的信道相干块上没有明显变化的事实，我们首先估计包括第一个相干块中的所有角度和增益信息的完整信道状态信息（CSI），然后仅重新估计剩余相干块中的信道增益，具有低得多的导频开销。在第一个相干模块中，我们提出了一种两阶段信道估计方法，在第一阶段中，基于级联路径之间的线性相关性估计出一个典型用户的级联信道，而在第二阶段中，利用第一阶段中获得的公共基站（BS）-RIS信道的重新参数化CSI来估计其他用户的级联信道。最小导频开销远低于现有的作品。仿真结果表明，在相同的导频开销下，该方法的估计精度优于现有方法。
Reconfigurable intelligent surface (RIS) is a promising device that can reconfigure the electromagnetic propagation environment through adjustment of the phase shifts of its reflecting elements. However, channel estimation in RIS-aided multiuser multiple-input single-output (MU-MISO) wireless communication systems is challenging due to the passive nature of the RIS and the large number of reflecting elements that can lead to high channel estimation overhead. To address this issue, we propose a novel cascaded channel estimation strategy with low pilot overhead by exploiting the sparsity and the correlation of multiuser cascaded channels in millimeter-wave MISO systems. Based on the fact that the physical positions of the BS, the RIS and users do not appreciably change over multiple consecutive channel coherence blocks, we first estimate the full channel state information (CSI) including all the angle and gain information in the first coherence block, and then only re-estimate the channel gains in the remaining coherence blocks with much lower pilot overhead. In the first coherence block, we propose a two-phase channel estimation method, in which the cascaded channel of one typical user is estimated in Phase I based on the linear correlation among cascaded paths, while the cascaded channels of other users are estimated in Phase II by utilizing the reparameterized CSI of the common base station (BS)-RIS channel obtained in Phase I. The minimum pilot overhead is much less than the existing works. Simulation results show that the performance of the proposed method outperforms the existing methods in terms of the estimation accuracy when using the same amount of pilot overhead.