In wireless systems aided by reconfigurable intelligent surfaces (RISs), channel state information (CSI) plays a pivotal role in achieving the performance gain of RISs. In this letter, we propose a novel Doppler shift adjustment (DSA) method to improve CSI estimation accuracy in the presence of motions at the communication ends for RIS-assisted systems. Specifically, the estimated channel frequency response is transformed into the time domain to facilitate phase shift adjustment, which is then converted back to the frequency domain. The proposed DSA necessitates only one more symbol which incurs negligible extra overhead compared with the large number of symbols originally required for channel estimation. Further, low-complexity channel estimation and DSA schemes are designed for approximately single-path scenarios applicable to millimeter-wave and terahertz systems. Simulation results demonstrate the effectiveness of the proposed DSA and channel estimation methods.

中文翻译：

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考虑多普勒效应的可重构智能表面辅助无线通信信道估计


在可重构智能表面 (RIS) 辅助的无线系统中，信道状态信息 (CSI) 在实现 RIS 性能增益方面发挥着关键作用。在这封信中，我们提出了一种新颖的多普勒频移调整（DSA）方法，以提高 RIS 辅助系统通信端存在运动时的 CSI 估计精度。具体而言，将估计的信道频率响应变换到时域以便于相移调整，然后将其变换回频域。所提出的DSA只需要多一个符号，与信道估计最初所需的大量符号相比，这产生的额外开销可以忽略不计。此外，低复杂度的信道估计和DSA方案是为适用于毫米波和太赫兹系统的近似单路径场景而设计的。仿真结果证明了所提出的 DSA 和信道估计方法的有效性。