Design of a Multi-User RIS-Aided System with Statistical Channel Knowledge

Fuente: arXiv
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Autori principali: Syed, Sadaf, Semmler, Dominik, Amor, Donia Ben, Joham, Michael, Utschick, Wolfgang
Natura: Preprint
Pubblicazione: 2024
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author Syed, Sadaf
Semmler, Dominik
Amor, Donia Ben
Joham, Michael
Utschick, Wolfgang
author_facet Syed, Sadaf
Semmler, Dominik
Amor, Donia Ben
Joham, Michael
Utschick, Wolfgang
contents Reconfigurable intelligent surface (RIS) is a promising technology to enhance the spectral and energy efficiency in a wireless communication system. The design of the phase shifts of an RIS in every channel coherence interval demands a huge training overhead, making its deployment practically infeasible. The design complexity can be significantly reduced by exploiting the second-order statistics of the channels. This paper is the extension of our previous work to the design of an RIS for the multi-user setup, where we employ maximisation of the lower bound of the achievable sum-rate of the users. Unlike for the single-user case, obtaining a closed-form expression for the update of the filters and phase shifts is more challenging in the multi-user case. We resort to the fractional programming (FP) approach and the non-convex block coordinate descent (BCD) method to solve the optimisation problem. As the phase shifts of the RIS obtained by the proposed algorithms are based on the statistical channel knowledge, they do not need to be updated in every channel coherence interval.
format Preprint
id arxiv_https___arxiv_org_abs_2405_08585
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Design of a Multi-User RIS-Aided System with Statistical Channel Knowledge
Syed, Sadaf
Semmler, Dominik
Amor, Donia Ben
Joham, Michael
Utschick, Wolfgang
Signal Processing
Reconfigurable intelligent surface (RIS) is a promising technology to enhance the spectral and energy efficiency in a wireless communication system. The design of the phase shifts of an RIS in every channel coherence interval demands a huge training overhead, making its deployment practically infeasible. The design complexity can be significantly reduced by exploiting the second-order statistics of the channels. This paper is the extension of our previous work to the design of an RIS for the multi-user setup, where we employ maximisation of the lower bound of the achievable sum-rate of the users. Unlike for the single-user case, obtaining a closed-form expression for the update of the filters and phase shifts is more challenging in the multi-user case. We resort to the fractional programming (FP) approach and the non-convex block coordinate descent (BCD) method to solve the optimisation problem. As the phase shifts of the RIS obtained by the proposed algorithms are based on the statistical channel knowledge, they do not need to be updated in every channel coherence interval.
title Design of a Multi-User RIS-Aided System with Statistical Channel Knowledge
topic Signal Processing
url https://arxiv.org/abs/2405.08585