Two-Timescale Channel Estimation for Reconfigurable Intelligent Surface Aided Wireless Communications

By Chenxi Hu, Linglong Dai, Shuangfeng Han, Xiaoyun Wang. IEEE Transactions on Communications, 2019

395 citations recorded by the source corpus.

Channel estimation is challenging for the reconfigurable intelligent surface (RIS)-aided wireless communications. Since the number of coefficients of the cascaded channel among the base station (BS), the RIS, and the user equipment (UE), is the product of the number of BS antennas, the number of RIS elements, and the number of UEs, the pilot overhead can be prohibitively high. In this paper, we propose a two-timescale channel estimation framework to exploit the property that the BS-RIS channel is high-dimensional but quasi-static, while the RIS-UE channel is mobile but low-dimensional. Specifically, to estimate the quasi-static BS-RIS channel, we propose a dual-link pilot transmission scheme, where the BS transmits downlink pilots and receives uplink pilots reflected by the RIS. Then, we propose a coordinate descent-based algorithm to recover the BS-RIS channel. Since the quasi-static BS-RIS channel is estimated less frequently than the mobile channel is, the average pilot overhead can be reduced from a long-term perspective. Although the mobile RIS-UE channel has to be frequently estimated in a small timescale, the associated pilot overhead is low thanks to its low dimension. Simulation results show that the proposed two-timescale channel estimation framework can achieve accurate channel estimation with low pilot overhead.

Subfields: Aerospace Engineering, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/e614cf85672d7899b10103edf106c8d83aaaaa6f

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Citations in the corpus

Smart Radio Environments Empowered by Reconfigurable Intelligent Surfaces: How It Works, State of Research, and The Road Ahead (2020, background): “In [106], the authors propose a two-timescale channel estimation framework.”
Intelligent Reflecting Surface-Aided Wireless Communications: A Tutorial (2020, neutral): “In [115], [126], the static BS-IRS channel”
Edge Artificial Intelligence for 6G: Vision, Enabling Technologies, and Applications (2021, background): “To address this unique challenge, the common reflective channels among all edge devices [281], quasi-static property between RIS and edge server channel links [282], [283], spatial features of”
IRS-Assisted Secure UAV Transmission via Joint Trajectory and Beamforming Design (2022, neutral): “Based on the existing channel estimation approaches for IRS-assisted communications [34], we assume that all the channel state information (CSI) is available in this paper.”
A Joint Precoding Framework for Wideband Reconfigurable Intelligent Surface-Aided Cell-Free Network (2020, methodology): “The existing research works about RIS include antenna design [20], physical model [21], channel estimation [22], joint precoding/beamforming [23], and etc.”
Smart Radio Environments Empowered by Reconfigurable Intelligent Surfaces: How it Works, State of Research, and Road Ahead (2020, background): “In [106], the authors propose a two-timescale channel estimation framework.”