Dual-Polarized Beyond Diagonal RIS

TL;DR

This paper explores the fundamental limits of dual-polarized beyond diagonal RIS systems, revealing that group-connected configurations with small group sizes outperform conventional RIS in various channel conditions while reducing circuit complexity.

Contribution

It introduces the analysis of dual-polarized BD-RIS, deriving performance scaling laws and Pareto trade-offs, and demonstrates the advantages of group-connected RIS with group size 2.

Findings

Group-connected RIS with group size 2 outperforms conventional RIS.

Performance gains are observed in Rayleigh and LoS channels.

Reduced circuit complexity compared to traditional RIS architectures.

Abstract

Beyond diagonal reconfigurable intelligent surface (BD-RIS) is a family of RIS architectures more flexible than conventional RIS. While BD-RIS has been primarily analyzed assuming uni-polarized systems, modern wireless deployments are dual-polarized. To address this gap, this paper investigates the fundamental limits of dual-polarized BD-RIS-aided systems. We derive the scaling laws governing the performance of BD-RIS and the Pareto frontier of the trade-off between performance and circuit complexity enabled by BD-RIS. Theoretical results show that the group-connected RIS with group size 2 provides remarkable gains over conventional RIS in both Rayleigh and line-of-sight (LoS) channels, while maintaining a reduced circuit complexity.