Fluid Antenna-Enhanced Flexible Beamforming

TL;DR

This paper introduces a flexible beamforming framework for fluid antenna arrays, transforming beam-pattern synthesis into a sparse regression problem and demonstrating improved accuracy over traditional fixed-array systems.

Contribution

It develops a unified framework connecting beam-pattern synthesis with port selection, using compressive sensing and FFT-based phase retrieval for efficient, high-resolution adaptive beamforming.

Findings

Enhanced beam-pattern reconstruction accuracy with fluid antennas

Efficient FFT-based phase retrieval with low complexity

Significant improvement over fixed-array architectures

Abstract

Fluid antenna systems encompass a broad class of reconfigurable antenna technologies that offer substantial spatial diversity for various optimization objectives and communication tasks. Their capability to enhance spatial resolution within a fixed physical aperture makes fluid antennas particularly attractive for next-generation wireless deployments. In this work, we focus on the beamforming problem using a two-dimensional planar fluid antenna array. Since both narrow-beam and broad-beam patterns are essential in practical communication networks, enabling flexible beamforming through fluid antennas becomes an important and interesting research direction. We establish a unified and flexible framework that connects arbitrary beam-pattern synthesis with fluid-antenna port selection. The resulting formulation transforms beam-pattern reconstruction into a sparse regression problem, which is addressed using a tailored compressive sensing algorithm designed to operate efficiently with the fast Fourier transform (FFT). Furthermore, to ensure physically consistent phase modeling in the desired beam, we introduce an iterative FFT-based phase retrieval method. Owing to its structure, the proposed phase-refinement procedure exhibits low computational complexity and rapid convergence, requiring only one FFT and one inverse FFT per iteration. Simulation results demonstrate the effectiveness of the proposed flexible beamforming framework. Compared with conventional fixed-array architectures, fluid antennas exhibit significantly improved beam-pattern reconstruction accuracy, highlighting their potential for high-resolution and adaptive beamforming in future wireless systems.