Low-Interference Near-Field Multi-User Communication Enabled by Spatially Converging Multi-Mode Vortex Waves

TL;DR

This paper introduces a near-field multi-user communication scheme using multi-mode vortex waves and a reconfigurable metasurface to focus energy on multiple users, reducing interference and enabling efficient spatial multiplexing.

Contribution

It presents a novel near-field SDM system employing vortex waves and a reconfigurable metasurface for low-interference multi-user communication.

Findings

Effective multi-user spatial multiplexing demonstrated in near-field.

Significant reduction in inter-user interference achieved.

Real-time communication validated in practical scenarios.

Abstract

This paper proposes a multi-user Spatial Division Multiplexing (SDM) near-field access scheme, inspired by the orthogonal characteristics of multi-mode vortex waves. A Reconfigurable Meta-surface (RM) is ingeniously employed as the gateway for information transmission. This RM not only receives spatially overlapping multiplexed multi-mode vortex beams but also converts them into focused point beams in the near field. Specifically, a multi-port microstrip array method is utilized to generate multiple orthogonal vortex electromagnetic wave modes. Different ports serve as feeding points for baseband signals, allowing independent modulated data to be flexibly loaded onto different modes. After being adjusted by the RM, the vortex electromagnetic waves are converted into energy-focusing point beams, which can be directed to arbitrary 3D positions in the RM's near-field region and received by different users. Since the spatial positions of the point beams are non-overlapping, this approach not only ensures energy concentration but also significantly reduces inter-user interference. Near-field scanning results in a microwave anechoic chamber validate the effectiveness of this method, while real-time communication demonstrations confirm the system's capability for low-interference information multiplexing and transmission in practical scenarios.