Cascaded line‐of‐sight channel estimation for reconfigurable intelligent surface aided multi‐user uplink transmissions. Issue 12 (2nd September 2022)

• Record Type: Journal Article
• Authors: Xu, Yicheng; Chu, Hongyun; Xu, Pingping
• Is Part Of: Transactions on emerging telecommunications technologies. Volume 33:Issue 12(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-09-02
• Subjects: Telecommunication -- Periodicals; 384.05
• DOI: 10.1002/ett.4642
• Languages: English
• ISSNs: 2161-5748

Abstract

Abstract: The reconfigurable intelligent surface (RIS) is capable of remolding the wireless propagation environment, and thus it is assumed as a key technology to enable the potentials of intelligent communications. For the RIS enabled multi‐user systems, channel estimation is rather challenging due to the passivity of the RIS without signal processing capability, where the channel is cascaded of the base station (BS)‐RIS and the RIS‐user equipments (UEs) paths. In this article, we propose an off‐grid channel estimation method for the RIS enabled multi‐user transmissions, exploiting the cascaded sparsity in the UEs‐RIS‐BS channel model. Specifically, we first reveal the cascaded sparsity, that is, the sparsity exists in the hybrid angular domains of UEs‐RIS and RIS‐BS separated channel. Then, we formulate the cascaded channel estimation problem as a semi‐definite program using l 1 $$ {l}_1 $$ ‐type atomic norm minimization and extract the channel parameters using subspace resolution technologies. Simulation results show that the proposed channel estimator achieves higher performance compared with the existing art‐of‐states. Abstract : For the reconfigurable intelligent surface (RIS) enabled multi‐user systems, the cascaded channel estimation is rather challenging due to the passivity of the RIS. In this article, we propose an off‐grid channel estimation method for the RIS enabled multi‐user transmissions, exploiting the cascaded sparsity in the user equipments‐RIS‐base station channel.