Two-Timescale Design for Movable Antenna Array-Enabled Multiuser Uplink Communications

TL;DR

This paper proposes a two-timescale scheme for multiuser uplink communications using movable antenna arrays, optimizing antenna positions with statistical CSI and beamforming with instantaneous CSI to enhance ergodic sum rate.

Contribution

It introduces a novel two-timescale design for movable antenna arrays that reduces complexity and improves performance in multiuser uplink systems over Rician channels.

Findings

Movable antenna arrays outperform fixed-position arrays in sum rate.

The proposed algorithms effectively optimize antenna positions and beamforming.

Simulation shows significant performance gains with the proposed scheme.

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.