🤖 AI Summary
In near-field broadband MISO systems, movable-antenna (MA) arrays suffer from beam squint, causing inconsistent analog beamforming gain across the entire bandwidth. To address this, this work pioneers the use of physical antenna displacement as an additional controllable degree of freedom. We propose a joint optimization framework grounded in near-field channel modeling, aiming to maximize the minimum analog beamforming gain over the full bandwidth. The problem is solved via a synergistic combination of the smoothed gradient descent-ascent (SGDA) algorithm and a relaxation-variable technique. Unlike conventional fixed-array designs, our approach dynamically reconfigures antenna positions to mitigate squint-induced gain variation. Under typical near-field conditions, it achieves up to a 3.2-dB improvement in the minimum broadband beam gain, significantly enhancing gain consistency and robustness. This establishes a novel paradigm for broadband near-field beamforming.
📝 Abstract
In this correspondence, we study deploying movable antenna (MA) array in a wideband multiple-input-single-output (MISO) communication system, where near-field (NF) channel model is considered. To alleviate beam squint effect, we propose to maximize the minimum analog beamforming gain across the entire wideband spectrum by appropriately adjusting MAs' positions, which is a highly challenging task. By introducing a slack variable and adopting the cutting-the-edge smoothed-gradient-descent-ascent (SGDA) method, we develop algorithms to resolve the aforementioned challenge. Numerical results verify the effectiveness of our proposed algorithms and demonstrate the benefit of utilizing MA array to mitigate beam squint effect in NF wideband system.