Two-Timescale Design for Movable Antenna Array-Enabled Multiuser Uplink Communications
Guojie Hu, Qingqing Wu, Donghui Xu, Kui Xu, Jiangbo Si, Yunlong Cai, Naofal Al-Dhahir
TL;DR
This work addresses multiuser uplink with a movable-antenna (MA) base station under general Rician fading, where acquiring full instantaneous CSI across all possible MA positions is impractical. It introduces a two-timescale optimization: long-term antenna placement $\mathbf{x}$ is optimized using statistical CSI, followed by instantaneous CSI-based receive beamforming for the fixed MA layout. Three receiver schemes (ZF, MMSE, MMSE-SIC) are studied, each paired with a projected gradient ascent process to update $\mathbf{x}$, leading to scalable, locally optimal solutions (P2–P4). Simulation results show substantial ergodic sum-rate gains of MA over conventional fixed-position arrays, with gains increasing with the total antenna span and displaying diminishing returns as the number of movable antennas grows relative to the span, highlighting MA’s potential for practical uplink enhancements in crowded or highly-correlated channels.
Abstract
Movable antenna (MA) technology can flexibly reconfigure wireless channels by adjusting antenna positions in a local region, thus owing great potential for enhancing communication performance. This letter investigates MA technology enabled multiuser uplink communications over general Rician fading channels, which consist of a base station (BS) equipped with the MA array and multiple single-antenna users. Since it is practically challenging to collect all instantaneous channel state information (CSI) by traversing all possible antenna positions at the BS, we instead propose a two-timescale scheme for maximizing the ergodic sum rate. Specifically, antenna positions at the BS are first optimized using only the statistical CSI. Subsequently, the receiving beamforming at the BS (for which we consider the three typical zero-forcing (ZF), minimum mean-square error (MMSE) and MMSE with successive interference cancellation (MMSE-SIC) receivers) is designed based on the instantaneous CSI with optimized antenna positions, thus significantly reducing practical implementation complexities. The formulated problems are highly non-convex and we develop projected gradient ascent (PGA) algorithms to effectively handle them. Simulation results illustrate that compared to conventional fixed-position antenna (FPA) array, the MA array can achieve significant performance gains by reaping an additional spatial degree of freedom.