Mutual Information Optimization for SIM-Based Holographic MIMO Systems
In the context of emerging stacked intelligent metasurface (SIM)-based holographic MIMO (HMIMO) systems, a fundamental problem is to study the mutual information (MI) between transmitted and received signals to establish their capacity. However, direct optimization or analytical evaluation of the MI...
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Main Authors | , |
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Format | Journal Article |
Language | English |
Published |
27.03.2024
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Subjects | |
Online Access | Get full text |
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Summary: | In the context of emerging stacked intelligent metasurface (SIM)-based
holographic MIMO (HMIMO) systems, a fundamental problem is to study the mutual
information (MI) between transmitted and received signals to establish their
capacity. However, direct optimization or analytical evaluation of the MI,
particularly for discrete signaling, is often intractable. To address this
challenge, we adopt the channel cutoff rate (CR) as an alternative optimization
metric for the MI maximization. In this regard, we propose an alternating
projected gradient method (APGM), which optimizes the CR of a SIM-based HMIMO
system by adjusting signal precoding and the phase shifts across the transmit
and receive SIMs on a layer-by-layer basis. Simulation results indicate that
the proposed algorithm significantly enhances the CR, achieving substantial
gains, compared to the case with random SIM phase shifts, that are proportional
to those observed for the corresponding MI. This justifies the effectiveness of
using the channel CR for the MI optimization. Moreover, we demonstrate that the
integration of digital precoding, even on a modest scale, has a significant
impact on the ultimate performance of SIM-aided systems. |
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DOI: | 10.48550/arxiv.2403.18307 |