Holographic Airy Beamforming: Curved Trajectory Optimization for Blockage-Resilient Terahertz Communications

TL;DR

This paper introduces a holographic Airy beamforming technique using reconfigurable holographic surfaces to create curved trajectories that bypass obstacles in terahertz communications, significantly improving signal resilience.

Contribution

It proposes a novel analog beamforming scheme with amplitude control on RHS for precise wavefront engineering and develops a trajectory optimization algorithm for blockage mitigation.

Findings

RHS enables over 10 dB improvement in received power for blocked users.

The proposed method effectively generates curved Airy beams along desired trajectories.

Simulation confirms enhanced blockage resilience compared to traditional phase-controlled arrays.

Abstract

Terahertz communication offers vast bandwidth for high-speed transmission in the 6G networks but faces severe blockage challenges in the near-field region due to large antenna arrays. To overcome the limitation that near-field focused beams are susceptible to obstacles, wavefront engineering is leveraged to generate an Airy beam that propagates along a parabolic trajectory to circumvent blockages. In this paper, we consider the reconfigurable holographic surface (RHS) as a potential solution for such precise wavefront engineering owing to its compact radiation element spacing being much smaller than half-wavelength. We reveal that the adjustable effective aperture of the RHS allows the parabolic offset to be located within the antenna aperture, which enhances the freedom in designing Airy beam trajectories. An analog beamforming method, named the holographic Airy beamforming scheme based on amplitude control, is then proposed to generate the curved beam that propagates along the desired trajectory. To maximize the received power of a blocked user, we develop a geometry-based trajectory optimization algorithm. Simulation results validate that, compared to traditional phase-controlled arrays with analog beamforming, the RHS can leverage its adjustable effective aperture to improve the received power of the blocked user by over 10 dB.