RIS: Spatial-Wideband Effect Analysis and Off-Grid Channel Estimation
JIAN Mengnan1, 2, ZHANG Nan1, 2, CHEN Yijian1, 2
(1. State Key Laboratory of Mobile Network and Mobile Multimedia Technology, Shenzhen 518055, China;
2. Algorithm Dept., Wireless Product R&D Institute, ZTE Corporation, Shenzhen 518057, China)
As a critical candidate technology for 5G-advanced and 6G, reconfigurable intelligent surfaces (RISs) have received extensive attention from academia and industry. RISs have the promising features of passiveness, reconfigurable ability, and low cost. RIS channel estimation faces the challenges of high matrix dimension, passive estimation, and spatial-wideband effect. In this article, we analyze the impact of the spatial-wideband effect on the RIS channel to account for the propagation delay across RIS elements and estimate sparse channel parameters such as angle and gain through a super-resolution compressive sensing (CS) algorithm. The simulation results explore the influence of the spatial-wideband effect on the RIS channel and verify the effectiveness of the proposed algorithm.
RIS; channel estimation; spatial-wideband effect; compressed sensing