Reconfigurable intelligent surface (RIS) has been anticipated to be a novel cost-effective technology to improve the performance of future wireless systems. In this paper, we investigate a practical RIS-aided multiple-input-multiple-output (MIMO) system in the presence of transceiver hardware impairments, RIS phase noise and imperfect channel state information (CSI). Joint design of the MIMO transceiver and RIS reflection matrix to minimize the total average mean-square-error (MSE) of all data streams is particularly considered. This joint design problem is non-convex and challenging to solve due to the newly considered practical imperfections. To tackle the issue, we first analyze the total average MSE by incorporating the impacts of the above system imperfections. Then, in order to handle the tightly coupled optimization variables and non-convex NP-hard constraints, an efficient iterative algorithm based on alternating optimization (AO) framework is proposed with guaranteed convergence, where each subproblem admits a closed-form optimal solution by leveraging the majorization-minimization (MM) technique. Moreover, via exploiting the special structure of the unit-modulus constraints, we propose a modified Riemannian gradient ascent (RGA) algorithm for the discrete RIS phase shift optimization. Furthermore, the optimality of the proposed algorithm is validated under line-of-sight (LoS) channel conditions, and the irreducible MSE floor effect induced by imperfections of both hardware and CSI is also revealed in the high signal-to-noise ratio (SNR) regime. Numerical results show the superior MSE performance of our proposed algorithm over the adopted benchmark schemes, and demonstrate that increasing the number of RIS elements is not always beneficial under the above system imperfections.
翻译:重新配置的智能表面(RIS)预计是一种创新的成本效益高的技术,可以改善未来无线系统的性能。在本文件中,我们调查了一个实用的RIS辅助的多投入-多输出输出(MIMO)系统,该系统存在收发机硬件缺陷、RIS阶段噪音和不完善的频道状态信息(CSI),因此,我们首先分析一个具有实际的RIS辅助的多投入-多输出(MIMO)系统,因为存在收发机硬件缺陷、RIS阶段噪音和不完善的频道状态信息(CSI)。MIMO收发机收发机和RIS反映射矩阵联合设计,以尽量减少所有数据流的总平均平均平方-平差(MSE)比率(MSE),这一联合设计的问题是非共通的,由于新考虑的硬件不完善,因此难以解决。 此外,我们通过SEOARS-RA的快速化(IM) IMLIMA) IMA 系统(S IMA) 升级的系统的特殊性能结构, 展示了我们不断升级的升级的系统。