|Message-Passing Based Channel Estimation for Reconfigurable Intelligent Surface Assisted MIMO
|Hang Liu, The Chinese University of Hong Kong, China; Xiaojun Yuan, University of Electronic Science and Technology of China, China; Ying-Jun Angela Zhang, The Chinese University of Hong Kong, China
|W.2: Intelligent Surface
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|In this paper, we study the channel acquisition problem in a reconfigurable intelligent surface (RIS) assisted multiuser multiple-input multiple-output (MIMO) system, where an RIS with fully passive phase-shift elements is deployed to assist the MIMO communication. The state-of-the-art channel acquisition approach in such a system estimates the cascaded transmitter-to-RIS and RIS-to-receiver channels by adopting excessively long training sequences. To estimate the cascaded channels with an affordable training overhead, we formulate the channel estimation problem as a matrix-calibration based matrix factorization task. By exploiting the information on the slow-varying channel components and the hidden channel sparsity, we propose a novel message-passing based algorithm to factorize the cascaded channels.