Fluid Antenna Hybrid Analog-Digital Architecture for Efficient 2-D DOA Estimation

Fluid antenna systems (FAS) dynamically optimize antenna positions to exploit spatial degrees of freedom, offering significant potential for high-precision direction of arrival (DOA) estimation. However, practical implementation faces challenges in hardware complexity and computational burden. This paper proposes an innovative FAS hybrid analog-digital (HAD) architecture that achieves efficient 2-D DOA estimation while reducing system complexity. The proposed architecture employs cooperative antenna movement and analog signal compression to minimize hardware requirements. We develop the FAS-HAD-MUSIC algorithm that leverages spatial-phase joint sampling for rapid and accurate DOA estimation. Simulation results demonstrate substantial improvements in both estimation accuracy and computational efficiency compared to conventional approaches, establishing a practical foundation for FAS technology deployment.