Nonlinear Precoding in the RIS-Aided MIMO Broadcast Channel

Fuente: arXiv
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Main Authors: Semmler, Dominik, Joham, Michael, Utschick, Wolfgang
Format: Preprint
Published: 2024
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author Semmler, Dominik
Joham, Michael
Utschick, Wolfgang
author_facet Semmler, Dominik
Joham, Michael
Utschick, Wolfgang
contents We propose to use Tomlinson-Harashima Precoding (THP) for the reconfigurable intelligent surface (RIS)-aided multiple-input multiple-output (MIMO) broadcast channel where we assume a line of sight (LOS) connection between the base station (BS) and the RIS. In this scenario, nonlinear precoding, like THP or dirty paper coding (DPC), has certain advantages compared to linear precoding as it is more robust in case the BS-RIS channel is not orthogonal to the direct channel. Additionally, THP and DPC allow a simple phase shift optimization which is in strong contrast to linear precoding for which the solution is quite intricate. Besides being difficult to optimize, it can be shown that linear precoding has fundamental limitations for statistical and random phase shifts which do not hold for nonlinear precoding. Moreover, we show that the advantages of THP/DPC are especially pronounced for discrete phase shifts.
format Preprint
id arxiv_https___arxiv_org_abs_2409_02464
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Nonlinear Precoding in the RIS-Aided MIMO Broadcast Channel
Semmler, Dominik
Joham, Michael
Utschick, Wolfgang
Signal Processing
We propose to use Tomlinson-Harashima Precoding (THP) for the reconfigurable intelligent surface (RIS)-aided multiple-input multiple-output (MIMO) broadcast channel where we assume a line of sight (LOS) connection between the base station (BS) and the RIS. In this scenario, nonlinear precoding, like THP or dirty paper coding (DPC), has certain advantages compared to linear precoding as it is more robust in case the BS-RIS channel is not orthogonal to the direct channel. Additionally, THP and DPC allow a simple phase shift optimization which is in strong contrast to linear precoding for which the solution is quite intricate. Besides being difficult to optimize, it can be shown that linear precoding has fundamental limitations for statistical and random phase shifts which do not hold for nonlinear precoding. Moreover, we show that the advantages of THP/DPC are especially pronounced for discrete phase shifts.
title Nonlinear Precoding in the RIS-Aided MIMO Broadcast Channel
topic Signal Processing
url https://arxiv.org/abs/2409.02464