Suppressing Beam Squint Effect For Near-Field Wideband Communication Through Movable Antennas (2407.19511v2)

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.

• The paper explores beam squint in near-field wideband movable antenna systems and proposes methods to suppress the effect.
• It proposes a max-min criterion for antenna positioning and introduces efficient algorithms, including SGDA, to optimize analog beamforming gain.
• The research has implications for improving the viability and performance of future high-frequency wideband wireless systems using movable antennas.

Suppressing Beam Squint Effect for Near-Field Wideband Communication through Movable Antennas

The paper "Suppressing Beam Squint Effect for Near-Field Wideband Communication Through Movable Antennas" by Yanze Zhu et al. presents an in-depth paper on deploying movable antenna (MA) arrays in wideband multiple-input-single-output (MISO) communication systems, particularly addressing the beam squint effect under a near-field (NF) channel model.

Overview

The advent of the fifth-generation (5G) communication systems has extended the demand for improved spectral efficiency, leading to the exploration of various advanced MIMO technologies. Movable antennas or fluid antennas introduce a novel approach, offering a dynamic degree of freedom unlike fixed position antenna (FPA) arrays. By allowing antenna elements to move within a specified area, MA arrays enhance spatial multiplexing gains. This paper focuses on mitigating the beam squint effect—a significant challenge in wideband systems where analog beamforming gain degrades as subcarrier frequency deviates from the central frequency—by utilizing MAs in NF environments.

Contributions

1. Beam Squint in NF Wideband Systems: The paper explores beam squint effects specifically within NF wideband MA systems, an area previously underexplored. This is pivotal as NF channel models become crucial with enlarging antenna apertures and higher frequencies such as millimeter-wave (mmWave) and terahertz (THz).
2. Max-Min Criterion for MA Positioning: The authors propose a max-min approach to configure antenna positions, aiming to maximize the minimum analog beamforming gain across the entire spectrum, thus ensuring more balanced communication rates.
3. Algorithmic Solutions: Two algorithms are introduced to address the problem: a slack variable-based method and a smoothed-gradient-descent-ascent (SGDA) based approach. The SGDA method, in particular, stands out for its efficiency in handling systems with large bandwidth.

Numerical Results

Simulations confirm the algorithms' effectiveness in significantly alleviating the beam squint effect. Notably, the SGDA-based method demonstrates superior performance over the slack variable approach, both in terms of computational complexity and achieved beamforming gains, as validated across numerous subcarriers.

Implications and Future Work

This research holds substantial implications for the advancement of MA technology in NF wideband communication systems. By effectively addressing beam squint effects, the proposed methodologies could improve the viability and performance of future wireless systems characterized by wide spectral ranges and high-frequency operations.

Future developments might focus on extending these methods to multi-user scenarios and integrating advanced sensing techniques for real-time adjustments of MA positions, further enhancing the adaptability and efficiency of wireless networks. Additionally, investigating the interplay with other physical layer technologies, such as reconfigurable intelligent surfaces or advanced codec schemes, could yield further insights.

In summary, the paper offers substantial contributions to wideband communication through the deployment of MA arrays, addressing critical challenges and laying the groundwork for future innovations in high-efficiency wireless communications.