Channel Modeling and Multi-User Precoding for Tri-Polarized Holographic MIMO Communications

TL;DR

This paper explores the use of triple polarization in holographic MIMO systems to enhance capacity without increasing antenna size, introducing a new channel model and precoding scheme to mitigate interference.

Contribution

It proposes a novel TP near-field channel model and a user-cluster-based precoding scheme for multi-user holographic MIMO systems utilizing triple polarization.

Findings

Cross-polarization channels significantly affect performance.

Proposed precoding effectively mitigates cross-polarization interference.

System capacity is improved with the new scheme.

Abstract

This paper studies the exploitation of triple polarization (TP) for multi-user (MU) holographic multiple-input multiple-output surface (HMIMOS) wireless communication systems, aiming at capacity boosting without enlarging the antenna array size. We specifically consider that both the transmitter and receiver are equipped with an HMIMOS comprising compact sub-wavelength TP patch antennas. To characterize TP MUHMIMOS systems, a TP near-field channel model is proposed using the dyadic Green's function, whose characteristics are leveraged to design a user-cluster-based precoding scheme for mitigating the cross-polarization and inter-user interference contributions. A theoretical correlation analysis for HMIMOS with infinitely small patch antennas is also presented. According to the proposed scheme, the users are assigned to one of the three polarizations, which is easy to implement, at the cost, however, of reducing the system's diversity. Our numerical results showcase that the cross-polarization channel components have a nonnegligible impact on the system performance, which is efficiently eliminated with the proposed MU precoding scheme.