Random Virtual Antenna Arrays Assisted DoA Sensing in Passive Movement Scenarios

This letter proposes integrating virtual antenna arrays (VAAs) into smart portable and wearable devices for direction-of-arrival (DoA) estimation. The scheme achieves accurate DoA estimation by leveraging the passive movement (i.e., movement that is not preconfigured or controlled) of smart devices to form a random VAA structure in a one-dimensional scenario, a novel design that requires neither path optimization nor physical array scaling. We derive array factors for both single-antenna and multi-antenna random VAAs, comparing them with conventional uniform linear arrays (ULA) and physically randomly distributed linear arrays. Simulation results demonstrated that the random VAA achieves lower side lobe levels and reduced hardware costs. Notably, a single-antenna VAA with three random passive movements achieves a 1.04∘ DoA estimation error over a movable region up to 4λ, where traditional ULAs fail. Furthermore, the proposed scheme proves robust (0.56∘ estimation error) against position errors caused by imperfect movement measurement up to λ/3.