RIS辅助太赫兹通信的宽带上行信道估计

针对现有可重构智能表面(Reconfigurable Intelligent Surface, RIS)辅助通信系统的宽带信道估计方案只考虑了信道的频率选择性，而忽略波束斜视的影响导致性能下降的问题，提出了一种基于分组策略的分布式Dice子空间追踪(Distributed Dice Subspace Pursuit, DDSP)方案。首先，利用太赫兹(Terahertz, THz)信道的稀疏性，将级联信道估计问题转化为稀疏信号恢复问题；然后，设计了宽带字典和提出了一种分组策略来解决波束斜视的影响；最后，引入Dice系数准则和回溯思想优化支撑集的选择。仿真结果表明，所提算法相较于传统宽带信道估计方案能够提高信道估计的精确度。

Wideband Uplink Channel Estimation for RIS-Assisted Terahertz Communication

In reconfigurable intelligent surface (RIS) assisted communication systems, existing wideband channel estimation schemes only consider the frequency selectivity fading of the channel, and ignore the beam squint problem which degrades the system performance severely. Therefore, a distributed Dice subspace pursuit (DDSP) scheme based on a grouping strategy is proposed in this paper. First, the cascaded channel estimation problem is transformed into a sparse signal recovery problem by exploiting the sparsity of Terahertz (THz) channels. Then, a wideband dictionary is designed and a grouping strategy is proposed to solve the effect of beam squint. Finally, the Dice coefficient criterion and backtracking idea are introduced to optimize the selection of support set. The simulation results show that the proposed algorithm can improve the accuracy of channel estimation and outperforms the traditional wideband channel estimation schemes.