电子测量与仪器学报

佘开.智能反射表面辅助无线系统信道估计方法研究[J].电子测量与仪器学报,2025,39(5):262-269

智能反射表面辅助无线系统信道估计方法研究

Research on the channel estimation method of RIS-aided wireless system

DOI：

英文关键词:reconfigurable intelligent surfaces (RIS) channel estimation (CE) least square estimation (LSE) eigen decomposition two timescale method

基金项目:

作者	单位
佘开	1.湖南科技大学物理与电子科学学院湘潭411201； 2.湖南科技大学智能传感器与新型传感材料湖南省重点实验室湘潭411201

Author	Institution
She Kai	1.School of Physics and Electronic Science, Hunan University of Science and Technology, Xiangtan 411201, China; 2.Key Laboratory of Intelligent Sensors and Advanced Sensing Materials of Hunan Province, Xiangtan 411201, China

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中文摘要:

信道估计的高导频开销是智能反射表面(RIS)应用于无线系统时的主要挑战之一，双时间尺度信道估计策略利用基站-RIS间信道准静态的特点，能较好的降低导频开销。但该策略在估计基站 RIS信道时使用迭代优化算法，计算复杂度过高，并不适用于实时信道估计。对双时间尺度策略的基站-RIS间信道估计方法进行了研究，首先对接收的导频数据做矩阵补全，将信道估计方程近似为二阶非线性秩一优化问题，然后通过对梯度优化方程中的复数据矩阵进行分块和实表示，提出了一种基于主特征值分解的全局优化求解方法，该方法以半闭合表达式的形式建立了接收导频与信道参数间的联系。莱斯信道及典型天线配置条件下的仿真结果表明，提出方法较参考的迭代优化方法具有更低计算复杂度；当基站-RIS信道相干时间是RIS-用户信道相干时间的4倍时，能节省85%以上的导频开销；当接收导频信噪比低于16 dB时，估计精度高于迭代优化算法。提出的方法适用于对信道估计实时性要求高，或RIS远离基站而更靠近用户端的情形。

英文摘要:

The high pilot overhead of channel estimation (CE) poses a significant challenge that hinders the wider application of reconfigurable intelligent surfaces (RIS) in wireless systems. Two timescale CE strategy can reduce the pilot overhead effectively by leveraging the semi-stationary characteristic of the base station (BS)-RIS channels. However, this strategy is unsuitable for real-time CE due to its reliance on an iterative optimization algorithm for BS-RIS CE, which entails high computational complexity. This paper reconsiders the optimization method within the framework of two timescale CE strategy for BS-RIS channels. Firstly, after completing the received pilot data matrix, the CE equations are simplified to a second-order nonlinear rank-one optimization problem. Subsequently, the complex-valued matrix of received pilots in the gradient equations is decomposed in blocks and represented in real terms, and an optimization method based on principal eigenvalue approximation is proposed. The proposed method establishes a semi-closed-form relation between the received pilots and the channel parameters. For the scenario of Rician channel and typical antenna configurations, the simulation results show that the proposed method has lower computational complexity compared to the referenced iterative method. And it can reduce more than 85% pilot overhead when the channel coherent time of BS-RIS is 4 times of RIS-User channels. When the signal-to-noise ratio (SNR) of received pilots is less than 16 dB, the estimation accuracy surpasses that of the iterative algorithm. Consequently, the proposed CE method is more competitive in scenarios requiring high real-time CE or the scenarios that RIS is located far away from BS and close to users.

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