可重构智能表面辅助的多用户通信宽带信道估计

针对太赫兹(THz)链路的严重传输衰减和宽带系统中波束斜视导致传统信道估计方案性能下降的问题，该文构建了可重构智能表面(RIS)辅助多用户THz通信模型，并提出一种低复杂度的两阶段级联信道估计方案。在第1阶段，利用THz的稀疏性和对数和函数，将信道估计问题转化为目标优化问题，通过梯度下降法优化目标函数，使待估信道参数迭代逼近最优解，从而估计出典型用户级联信道；在第2阶段，利用其他用户的级联信道与典型用户信道的强相关性，以较低的导频开销来估计其他用户的级联信道。仿真结果表明，所提方案相较于其他方案具有更好的性能。

Wideband Channel Estimation for Multiuser Communication Based on Reconfigurable Intelligent Surface Assisted

To solve the problem of severe transmission attenuation of TeraHertz (THz) links, and the performance degradation of traditional channel estimation schemes caused by beam squint in wideband systems, a multi-user THz communication model assisted by Reconfigurable Intelligent Surfaces (RIS) is constructed in this paper, and a low complexity two-stage cascaded channel estimation scheme is proposed. In the first stage, the channel estimation problem is transformed into an objective optimization problem by using the sparsity of the THz and log-sum function, and the objective function is optimized by gradient descent method, so that the channel parameters to be estimated are iteratively close to the optimal solution, thus the typical user cascade channel is estimated. In the second stage, the cascade channels of other users are estimated with lower pilot overhead by using the strong correlation between the cascade channels of other users and the typical user channel. The simulation results show that the proposed scheme has better performance than other schemes.