Movable Antennas-aided Wireless Energy Transfer for the Internet of Things

TL;DR

This paper introduces a novel optimization algorithm for movable antennas in wireless energy transfer systems, significantly improving efficiency and scalability for IoT devices by dynamically adjusting antenna positions.

Contribution

It proposes a semidefinite program guided particle swarm optimization (SgPSO) for configuring movable antennas, outperforming fixed array setups and analyzing near-field effects.

Findings

SgPSO outperforms fixed array implementations, especially with more antennas or devices.

Uniformly-spaced MAs nearly match IMAs performance, with gaps widening as device count increases.

Increasing antennas promotes near-field conditions, affecting device distribution.

Abstract

Recent advancements in movable antennas (MAs) technology create new opportunities for 6G and beyond wireless systems. MAs are promising for radio frequency wireless energy transfer because they can dynamically adjust antenna positions, improving energy efficiency and scalability. This work aims to minimize the power consumed by an analog beamforming power beacon equipped with independently-controlled MAs (IMAs) for charging multiple single-antenna devices. To this end, we enforce a minimum separation among antennas and a minimum received power at the devices. The resulting optimization problem is nonlinear and nonconvex due to interdependencies among the variables. To tackle this, we propose a semidefinite program guided particle swarm optimization (SgPSO) algorithm where each particle represents an antenna configuration, and the fitness function optimizes the corresponding power allocation. SgPSO is utilized for configuring the MAs largely outperforming fixed array implementations, particularly with more antennas or devices. We also present an alternative implementation using uniformly-spaced MAs, whose performance closely approaches that of the IMAs, with the gap widening only as the number of devices grows. We also examine how increasing the number of antennas promotes near-field conditions, which decrease as devices become more widely distributed.