Flexible Cylindrical Array-Aided Secure Wireless Communications

TL;DR

This paper proposes a flexible cylindrical array system for secure multiuser wireless communication, optimizing beamforming and antenna placement to maximize sum rate while ensuring security against eavesdroppers.

Contribution

It introduces a novel joint optimization framework for beamforming, artificial noise, and antenna placement in a flexible array system, enhancing secure communication performance.

Findings

The proposed algorithm converges rapidly.

Achieves significant sum-rate improvements over benchmarks.

Exploits array geometry flexibility for better security and performance.

Abstract

Flexible-geometry arrays based on movable antennas have shown considerable potential for improving wireless communication performance. In this letter, we investigate a multiuser multiple-input single-output (MU-MISO) downlink secure communication system aided by a flexible cylindrical array (FCLA) and artificial noise (AN), where each antenna element rotates along circular tracks while the circular slices move along a vertical axis. To guarantee transmission security, we aim to maximize the achievable sum rate at multiple legitimate information receivers by jointly optimizing transmit beamforming, AN covariance matrix, and antenna placement under secrecy constraints for an eavesdropper. While the resulting problem is intractable to solve, we develop a block coordinate descent (BCD)-based framework that combines the Lagrangian dual transform, tight semidefinite relaxation (SDR), and Nesterov-accelerated projected gradient descent (PGD). Numerical results show that the proposed algorithm converges rapidly and achieves significant sum-rate gains over benchmark schemes by exploiting the geometry flexibility of the array.