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Multiuser Communications Aided by Cross-Linked Movable Antenna Array: Architecture and Optimization

Lipeng Zhu, He Sun, Wenyan Ma, Zhenyu Xiao, Rui Zhang

TL;DR

Simulation results demonstrate that the proposed CL-MA schemes significantly outperform conventional fixed-position antenna (FPA) systems and closely approach the theoretical lower bound on the total transmit power.

Abstract

Movable antenna (MA) has been regarded as a promising technology to enhance wireless communication performance by enabling flexible antenna movement. However, the hardware cost of conventional MA systems scales with the number of movable elements due to the need for independently controllable driving components. To reduce hardware cost, we propose in this paper a novel architecture named cross-linked MA (CL-MA) array, which enables the collective movement of multiple antennas in both horizontal and vertical directions. To evaluate the performance benefits of the CL-MA array, we consider an uplink multiuser communication scenario. Specifically, we aim to minimize the total transmit power while satisfying a given minimum rate requirement for each user by jointly optimizing the horizontal and vertical antenna position vectors (APVs), the receive combining at the base station (BS), and the transmit power of users. A globally lower bound on the total transmit power is derived, with closed-form solutions for the APVs obtained under the condition of a single channel path for each user. For the more general case of multiple channel paths, we develop a low-complexity algorithm based on discrete antenna position optimization. Additionally, to further reduce antenna movement overhead, a statistical channel-based antenna position optimization approach is proposed, allowing for unchanged APVs over a long time period. Simulation results demonstrate that the proposed CL-MA schemes significantly outperform conventional fixed-position antenna (FPA) systems and closely approach the theoretical lower bound on the total transmit power. Compared to the instantaneous channel-based CL-MA optimization, the statistical channel-based approach incurs a slight performance loss but achieves significantly lower movement overhead, making it an appealing solution for practical wireless systems.

Multiuser Communications Aided by Cross-Linked Movable Antenna Array: Architecture and Optimization

TL;DR

Simulation results demonstrate that the proposed CL-MA schemes significantly outperform conventional fixed-position antenna (FPA) systems and closely approach the theoretical lower bound on the total transmit power.

Abstract

Movable antenna (MA) has been regarded as a promising technology to enhance wireless communication performance by enabling flexible antenna movement. However, the hardware cost of conventional MA systems scales with the number of movable elements due to the need for independently controllable driving components. To reduce hardware cost, we propose in this paper a novel architecture named cross-linked MA (CL-MA) array, which enables the collective movement of multiple antennas in both horizontal and vertical directions. To evaluate the performance benefits of the CL-MA array, we consider an uplink multiuser communication scenario. Specifically, we aim to minimize the total transmit power while satisfying a given minimum rate requirement for each user by jointly optimizing the horizontal and vertical antenna position vectors (APVs), the receive combining at the base station (BS), and the transmit power of users. A globally lower bound on the total transmit power is derived, with closed-form solutions for the APVs obtained under the condition of a single channel path for each user. For the more general case of multiple channel paths, we develop a low-complexity algorithm based on discrete antenna position optimization. Additionally, to further reduce antenna movement overhead, a statistical channel-based antenna position optimization approach is proposed, allowing for unchanged APVs over a long time period. Simulation results demonstrate that the proposed CL-MA schemes significantly outperform conventional fixed-position antenna (FPA) systems and closely approach the theoretical lower bound on the total transmit power. Compared to the instantaneous channel-based CL-MA optimization, the statistical channel-based approach incurs a slight performance loss but achieves significantly lower movement overhead, making it an appealing solution for practical wireless systems.
Paper Structure (16 sections, 3 theorems, 35 equations, 11 figures, 1 algorithm)

This paper contains 16 sections, 3 theorems, 35 equations, 11 figures, 1 algorithm.

Table of Contents

  1. Introduction
  2. System Model
  3. Channel Model
  4. Problem Formulation
  5. Performance Analysis
  6. Optimization Algorithm
  7. Optimization of Transmit Power and Receive Combining
  8. Optimization of APVs
  9. Statistical Channel-based APV Optimization
  10. Performance Analysis
  11. Optimization Algorithm
  12. Performance Evaluation
  13. Conclusions
  14. Proof of Theorem \ref{['theo_bound']}
  15. Proof of Theorem \ref{['theo_bound_condition']}
  16. ...and 1 more sections

Key Result

Theorem 1

A lower bound on the transmit power of each user in problem eq_problem_ist is given by

Figures (11)

  • Figure 1: The architecture of the proposed CL-MA array.
  • Figure 2: The proposed CL-MA array enabled BS for multiuser communication.
  • Figure 3: Illustration of the coordinate system and spatial angles at the BS.
  • Figure 4: Illustration of the optimal APVs for $M \times N =2 \times 4$ and $K=3$.
  • Figure 5: Convergence evaluation of the proposed Algorithm \ref{['alg_APV']}.
  • ...and 6 more figures

Theorems & Definitions (6)

  • Theorem 1
  • proof
  • Theorem 2
  • proof
  • Theorem 3
  • proof