Joint Downlink-Uplink Channel Estimation for Non-Reciprocal RIS-Assisted Communications

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Main Authors: Gomes, Paulo R. B., Magalhães, Amarilton L., de Almeida, André L. F.
Format: Preprint
Published: 2024
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author Gomes, Paulo R. B.
Magalhães, Amarilton L.
de Almeida, André L. F.
author_facet Gomes, Paulo R. B.
Magalhães, Amarilton L.
de Almeida, André L. F.
contents Reconfigurable intelligent surface (RIS) is a recent low-cost and energy-efficient technology with potential applicability for future wireless communications. Performance gains achieved by employing RIS directly depend on accurate channel estimation (CE). It is common in the literature to assume channel reciprocity due to the facilities provided by this assumption, such as no channel feedback, beamforming simplification, and latency reduction. However, in practice, due to hardware limitations at the RIS and transceivers, the channel non-reciprocity may occur naturally, so such behavior needs to be considered. In this paper, we focus on the CE problem in a non-reciprocal RIS-assisted multiple-input multiple-output (MIMO) wireless communication system. Making use of a novel closed-loop three-phase protocol for non-reciprocal CE estimation, we propose a two-stage fourth-order Tucker decomposition-based CE algorithm. In contrast to classical time-division duplexing (TDD) and frequency-division duplexing (FDD) approaches the proposed method concentrates all the processing burden for CE on the base station (BS) side, thereby freeing hardware-limited user terminal (UT) from this task. Our simulation results show that the proposed method has satisfactory performance in terms of CE accuracy compared to benchmark FDD LS-based and tensor-based techniques.
format Preprint
id arxiv_https___arxiv_org_abs_2412_16301
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Joint Downlink-Uplink Channel Estimation for Non-Reciprocal RIS-Assisted Communications
Gomes, Paulo R. B.
Magalhães, Amarilton L.
de Almeida, André L. F.
Signal Processing
Reconfigurable intelligent surface (RIS) is a recent low-cost and energy-efficient technology with potential applicability for future wireless communications. Performance gains achieved by employing RIS directly depend on accurate channel estimation (CE). It is common in the literature to assume channel reciprocity due to the facilities provided by this assumption, such as no channel feedback, beamforming simplification, and latency reduction. However, in practice, due to hardware limitations at the RIS and transceivers, the channel non-reciprocity may occur naturally, so such behavior needs to be considered. In this paper, we focus on the CE problem in a non-reciprocal RIS-assisted multiple-input multiple-output (MIMO) wireless communication system. Making use of a novel closed-loop three-phase protocol for non-reciprocal CE estimation, we propose a two-stage fourth-order Tucker decomposition-based CE algorithm. In contrast to classical time-division duplexing (TDD) and frequency-division duplexing (FDD) approaches the proposed method concentrates all the processing burden for CE on the base station (BS) side, thereby freeing hardware-limited user terminal (UT) from this task. Our simulation results show that the proposed method has satisfactory performance in terms of CE accuracy compared to benchmark FDD LS-based and tensor-based techniques.
title Joint Downlink-Uplink Channel Estimation for Non-Reciprocal RIS-Assisted Communications
topic Signal Processing
url https://arxiv.org/abs/2412.16301