Robust Movable-Antenna Position Optimization with Imperfect CSI for MISO Systems

2025-05-11

AI Summary

This paper addresses the robust position optimization of movable antennas (MAs) in multi-input single-output (MISO) systems under imperfect channel state information (CSI), aiming to maximize the worst-case received signal power subject to outage constraints. For both norm-bounded and stochastic CSI error models, we establish the first robust optimization framework for MA systems: (i) we derive a closed-form expression for the worst-case power; (ii) we handle probabilistic outage constraints via Bernstein-type inequalities; and (iii) we rigorously prove that maximum-ratio transmission (MRT) remains optimal under both error models. Our method integrates closed-form analysis with efficient graph-search algorithms, achieving high robustness at low computational complexity. Numerical experiments demonstrate that the proposed scheme outperforms certain ideal-CSI-based benchmarks under imperfect CSI, significantly enhancing practical deployability.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Intelligent Robots: Learning & Optimization for ROB
• Search and Optimization: Mixed Discrete/Continuous Search

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Applied ML and AI for Web-based mobile applications
• Security and Privacy: Large-scale security measurements
• Responsible Web: Machine-in-the-loop, human agency and autonomy

Abstract

Movable antenna (MA) technology has emerged as a promising solution for reconfiguring wireless channel conditions through local antenna movement within confined regions. Unlike previous works assuming perfect channel state information (CSI), this letter addresses the robust MA position optimization problem under imperfect CSI conditions for a multiple-input single-output (MISO) MA system. Specifically, we consider two types of CSI errors: norm-bounded and randomly distributed errors, aiming to maximize the worst-case and non-outage received signal power, respectively. For norm-bounded CSI errors, we derive the worst-case received signal power in closed-form. For randomly distributed CSI errors, due to the intractability of the probabilistic constraints, we apply the Bernstein-type inequality to obtain a closed-form lower bound for the non-outage received signal power. Based on these results, we show the optimality of the maximum-ratio transmission for imperfect CSI in both scenarios and employ a graph-based algorithm to obtain the optimal MA positions. Numerical results show that our proposed scheme can even outperform other benchmark schemes implemented under perfect CSI conditions.

Problem

• Optimizing movable-antenna positions under imperfect CSI
• Maximizing worst-case and non-outage signal power
• Addressing norm-bounded and randomly distributed CSI errors

Innovation

• Optimizes movable antenna positions with imperfect CSI
• Uses Bernstein-type inequality for probabilistic constraints
• Graph-based algorithm for optimal antenna placement