🤖 AI Summary
This work addresses the challenge of port activation in fluid antenna arrays under limited RF chain constraints, where existing approaches struggle to jointly optimize communication rate, aperture sparsity, and feed feasibility. To overcome this limitation, the paper proposes an Impedance-Aware Zonal Port Activation (IA-ZPA) method that uniquely integrates mutual coupling effects with real-time channel state information (CSI) into the port selection process. IA-ZPA leverages a learnable CSI-driven scoring network, a checkerboard-inspired feasibility projection, and a mutual-impedance-aware selection mechanism to achieve efficient sparse configurations. Furthermore, it incorporates current-domain regularized zero-forcing (RZF) beamforming and models mutual impedance under an induced electromotive force protocol. Experimental results demonstrate that, under average sidelobe level constraints, IA-ZPA significantly outperforms greedy strategies by achieving the highest constrained transmission rate while substantially reducing decision latency.
📝 Abstract
Fluid antenna array (FAA) activation jointly determines the effective multi-user channel for precoding and the sparse physical aperture. Channel-oriented selection can concentrate high-gain ports and erode aperture quality, whereas geometry-oriented selection does not adapt to instantaneous channel state information (CSI). This paper formulates finite-port FAA activation as a rate--aperture--feasibility problem under an exact RF-chain budget. We propose impedance-aware zonal port activation (IA-ZPA), which couples compact CSI-conditioned port scoring with a checkerboard feasibility projection and inference-time mutual-impedance-aware selection. The learned scorer ranks ports, while the deterministic rule fixes the active aperture; a separate current-domain RZF backend then evaluates source-drive feasibility. Under a common induced-EMF protocol, IA-ZPA attains the largest constrained rate among the methods satisfying the prescribed mean-PSLL target with a substantially lower decision time than greedy selection.