Time-Varying Channel Estimation and Extrapolation for XL-HRIS Aided Mobile Multiuser Systems
Zhizheng Lu, Yu Han, Mengyuan Li, Shi Jin · IEEE Transactions on Vehicular Technology · 2025
In this paper, to improve the accuracy of cascade channel reconstruction for extremely large-scale hybrid reconfigurable intelligent surface (XL-HRIS) aided mobile multiple-user equipment (UE) systems, an efficient time-varying channel estimation and extrapolation scheme is proposed. The optimal active element selection scheme is designed for HRIS, while a suboptimal phase shift strategy is proposed for HRIS to increase the received power at the BS. Meanwhile, an efficient multiple-UE joint channel estimation (MUJCE) algorithm is proposed, which can jointly estimate the channel parameters based on the common sparsity among multiple-UE channels with low pilot overhead. Moreover, to reduce the computational complexity of the frequent time-varying channel estimation between mobile UEs and the XL-HRIS, an efficient channel extrapolation scheme based on channel consistency (TVEC) is proposed, which utilizes the estimated common scatterers to extrapolate the near-field channel with significantly reduced computational complexity. Furthermore, a cluster-based environment sensing algorithm is also introduced, which can locate the positions of scatterers in the channel and track mobile UEs accurately. Our simulation results prove that the MUJCE algorithm can estimate the channel accurately, while the proposed phase shift strategy and active element selection scheme can further strengthen the accuracy of the estimates. Concurrently, the TEVC scheme can effectively extrapolate the near-field channel with reduced computational complexity, while the channel environment can be sensed precisely.