论文标题
使用Zadoff-Chu序列的RIS辅助MIMO的通道估计和投影
Channel Estimation and Projection for RIS-assisted MIMO Using Zadoff-Chu Sequences
论文作者
论文摘要
可重构的智能表面（RIS）技术是毫米波（MMWave）无线通信的有前途的推动力，因为它可以提供与常规大规模多输入多输出（MIMO）相当的光谱效率，但具有明显较低的硬件复杂性。在本文中，我们关注上行链路辅助大规模的MIMO通道的估计和投影，这可能是时间变化的。我们建议让用户设备（UE）传输Zadoff-Chu（ZC）序列，并让基站（BS）进行上行链路通道的最大似然（ML）估计。所提出的方案在计算上是有效的：它使用ZC序列将频率和时间偏移的估计分离；它使用空间偏置的广义期望最大化方法（SAGE）方法来减少高维问题，因为多径到每路路径的多个较低维度。由于估计多普勒频率偏移，可以预测随时间变化的通道状态，这可以显着降低飞行员的开销以进行通道估计。数值模拟验证了提出的方案的有效性。
The reconfigurable intelligent surface (RIS) technology is a promising enabler for millimeter wave (mmWave) wireless communications, as it can potentially provide spectral efficiency comparable to the conventional massive multiple-input multiple-output (MIMO) but with significantly lower hardware complexity. In this paper, we focus on the estimation and projection of the uplink RIS-aided massive MIMO channel, which can be time-varying. We propose to let the user equipments (UE) transmit Zadoff-Chu (ZC) sequences and let the base station (BS) conduct maximum likelihood (ML) estimation of the uplink channel. The proposed scheme is computationally efficient: it uses ZC sequences to decouple the estimation of the frequency and time offsets; it uses the space-alternating generalized expectation-maximization (SAGE) method to reduce the high-dimensional problem due to the multipaths to multiple lower-dimensional ones per path. Owing to the estimation of the Doppler frequency offsets, the time-varying channel state can be projected, which can significantly lower the overhead of the pilots for channel estimation. The numerical simulations verify the effectiveness of the proposed scheme.
