Movable Antenna Aided Hybrid Beamforming for Wideband MIMO Radar Sensing

Hybrid beamforming is a technique for reducing the hardware complexity and power consumption of MIMO radars. However, it inherently exhibits performance limitations compared to fully digital architectures. It is known that movable antenna (MA) arrays significantly enhance MIMO communication. In this paper, we introduce MA array-assisted hybrid beamforming for wideband MIMO radar to improve sensing performance. By jointly designing MA element positions, digital beamformers, and analog beamformers, we aim to minimize the spatial spectrum matching error (SSME). The resulting optimization problem is non-convex and NP-hard due to the constant modulus constraint, transmit power limitations, and MA positioning restrictions. To address this challenge, we propose a two-stage Riemannian manifold optimization (Ts RMO) method, which effectively decouples the problem into subproblems and leverages manifold optimization techniques for efficient solutions. Numerical results demonstrate that, compared to conventional fixed-position antenna (FPA)-based hybrid and even fully digital beamforming schemes, the proposed method achieves lower sidelobe levels and reduced SSME, thereby enhancing spatial resolution and sensing accuracy.