REMAA: Reconfigurable Pixel Antenna-based Electronic Movable-Antenna Arrays for Multiuser Communications
Kangjian Chen, Chenhao Qi, Yujing Hong, Chau Yuen
TL;DR
The paper tackles multiuser communications with reconfigurable pixel antenna (REMA) based electronic movable antennas (REMAs) by formulating a sum-rate maximization under hardware constraints for PC-REMAA and FC-REMAA. It introduces a two-step TS-MBAS scheme comprising TL-JBAS with penalty relaxation and a coordinate-descent enhancement to jointly optimize beamforming and antenna selection, and benchmarks REMAs against MMAs using a MMA-focused ABAPO framework. A Fourier-domain analysis provides a bound on REMA power loss relative to continuous-position MMAs, showing a maximum loss of $3.25\%$ for a $0.1\lambda$ position interval, with simulations demonstrating near-MMA performance for FC-REMAA under practical grids. Collectively, the work demonstrates that discretized REMAs, especially FC-REMAA, can closely approximate continuous movable antenna performance while offering reduced hardware complexity compared to full MMAs. The results indicate REMAs as a viable, flexible alternative for high-rate, multiuser systems in realistic deployment scenarios.
Abstract
In this paper, we investigate reconfigurable pixel antenna (RPA)-based electronic movable antennas (REMAs) for multiuser communications. First, we model each REMA as an antenna characterized by a set of predefined and discrete selectable radiation positions within the radiating region. Considering the trade-off between performance and cost, we propose two types of REMA-based arrays: the partially-connected RPA-based electronic movable-antenna array (PC-REMAA) and fully-connected REMAA (FC-REMAA). Then, we formulate a multiuser sum-rate maximization problem subject to the power constraint and hardware constraints of the PC-REMAA or FC-REMAA. To solve this problem, we propose a two-step multiuser beamforming and antenna selection scheme. In the first step, we develop a two-loop joint beamforming and antenna selection (TL-JBAS) algorithm. In the second step, we apply the coordinate descent method to further enhance the solution of the TL-JBAS algorithm. In addition, we revisit mechanical movable antennas (MMAs) to establish a benchmark for evaluating the performance of REMA-enabled multiuser communications, where MMAs can continuously adjust the positions within the transmission region. We also formulate a sum-rate maximization problem for MMA-enabled multiuser communications and propose an alternating beamforming and antenna position optimization scheme to solve it. Finally, we analyze the performance gap between REMAs and MMAs. Based on Fourier analysis, we derive the maximum power loss of REMAs compared to MMAs for any given position interval. Specifically, we show that the REMA incurs a maximum power loss of only 3.25\% compared to the MMA when the position interval is set to one-tenth of the wavelength. Simulation results demonstrate the effectiveness of the proposed methods.