Optimum Beamforming and Grating Lobe Mitigation for Intelligent Reflecting Surfaces

Fuente: arXiv
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Main Authors: Narayanan, Sai Sanjay, Khankhoje, Uday K, Ganti, Radha Krishna
Format: Preprint
Published: 2024
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author Narayanan, Sai Sanjay
Khankhoje, Uday K
Ganti, Radha Krishna
author_facet Narayanan, Sai Sanjay
Khankhoje, Uday K
Ganti, Radha Krishna
contents Ensuring adequate wireless coverage in upcoming communication technologies such as 6G is expected to be challenging. This is because user demands of higher datarate require an increase in carrier frequencies, which in turn reduce the diffraction effects (and hence coverage) in complex multipath environments. Intelligent reflecting surfaces have been proposed as a way of restoring coverage by adaptively reflecting incoming electromagnetic waves in desired directions. This is accomplished by judiciously adding extra phases at different points on the surface. In practice, these extra phases are only available in discrete quantities due to hardware constraints. Computing these extra phases is computationally challenging when they can only be picked from a discrete distribution, and existing approaches for solving this problem were either heuristic or based on evolutionary algorithms. We solve this problem by proposing fast algorithms with provably optimal solutions. Our algorithms have linear complexity, and are presented with rigorous proofs for their optimality. We show that the proposed algorithms exhibit better performance. We analyze situations when unwanted grating lobes arise in the radiation pattern, and discuss mitigation strategies, such as the use of triangular lattices and prephasing techniques, to eliminate them. We also demonstrate how our algorithms can leverage these techniques to deliver optimum beamforming solutions.
format Preprint
id arxiv_https___arxiv_org_abs_2404_09215
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Optimum Beamforming and Grating Lobe Mitigation for Intelligent Reflecting Surfaces
Narayanan, Sai Sanjay
Khankhoje, Uday K
Ganti, Radha Krishna
Signal Processing
Optimization and Control
Ensuring adequate wireless coverage in upcoming communication technologies such as 6G is expected to be challenging. This is because user demands of higher datarate require an increase in carrier frequencies, which in turn reduce the diffraction effects (and hence coverage) in complex multipath environments. Intelligent reflecting surfaces have been proposed as a way of restoring coverage by adaptively reflecting incoming electromagnetic waves in desired directions. This is accomplished by judiciously adding extra phases at different points on the surface. In practice, these extra phases are only available in discrete quantities due to hardware constraints. Computing these extra phases is computationally challenging when they can only be picked from a discrete distribution, and existing approaches for solving this problem were either heuristic or based on evolutionary algorithms. We solve this problem by proposing fast algorithms with provably optimal solutions. Our algorithms have linear complexity, and are presented with rigorous proofs for their optimality. We show that the proposed algorithms exhibit better performance. We analyze situations when unwanted grating lobes arise in the radiation pattern, and discuss mitigation strategies, such as the use of triangular lattices and prephasing techniques, to eliminate them. We also demonstrate how our algorithms can leverage these techniques to deliver optimum beamforming solutions.
title Optimum Beamforming and Grating Lobe Mitigation for Intelligent Reflecting Surfaces
topic Signal Processing
Optimization and Control
url https://arxiv.org/abs/2404.09215