Extremely Large-Scale Movable Antennas for Multiuser Communications

Movable antenna (MA) is a promising technology for enhancing communication performance in future wireless networks. To unleash its potential, this paper proposes an extremely large-scale MA (XL-MA) architecture, enabling flexible subarray positioning over a large spatial region to exploit near-field effects and improve spatial multiplexing. An uplink XL-MA-enabled multiuser system is studied, where multiple single-antenna users distributed in a coverage area are served by a base station with multiple movable subarrays. A spatially non-stationary channel model is developed to capture near-field effects, and a closed-form approximation of the expected rate under maximum ratio combining is derived. Based on this, we formulate an antenna placement optimization problem to maximize the expected weighted sum rate, leveraging statistical channel conditions and user distribution. To solve this challenging problem efficiently, we propose a polynomial-time successive replacement algorithm. Simulations demonstrate that the proposed XL-MA placement achieves near-optimal performance and outperforms fixed-position antenna benchmarks.