Near-Field Variable-Width Beam Coverage and Codebook Design for XL-RIS

TL;DR

This paper introduces a variable-width beam generation algorithm for XL-RIS systems to improve beam coverage, alignment, and robustness, leading to enhanced spectral efficiency and reduced outage probability.

Contribution

It proposes a novel near-field variable-width beam generation algorithm and a joint codebook design for multi-XL-RIS systems, addressing narrow beam width challenges.

Findings

Achieves higher spectral efficiency for user equipment.

Reduces communication outage probability within codeword regions.

Demonstrates robustness to codeword region variations.

Abstract

To mitigate the issue of limited base station coverage caused by severe high-frequency electromagnetic wave attenuation, Extremely Large Reconfigurable Intelligent Surface (XL-RIS) has garnered significant attention due to its high beam gain. However, XL-RIS exhibits a narrower beam width compared to traditional RIS, which increases the complexity of beam alignment and broadcast. To address this problem, we propose a variable-width beam generation algorithm under the near-field assumption and apply it to the near-field codebook design for XL-RIS. Our algorithm can achieve beam coverage for arbitrarily shaped codeword regions and generate a joint codebook for the multi-XL-RIS system. The simulation results demonstrate that our proposed scheme enables user equipment (UE) to achieve higher spectral efficiency and lower communication outage probability within the codeword region compared to existing works. Furthermore, our scheme exhibits better robustness to codeword region location and area variations.