FIRES: Fluid Integrated Reflecting and Emitting Surfaces

TL;DR

This paper introduces FIRES, a novel fluid-based metasurface that combines reflection and emission capabilities, enabling dynamic control for multicast systems and outperforming traditional STAR-RIS designs.

Contribution

The paper presents a new fluid-integrated metasurface design that unifies reflection and transmission functionalities with dynamic reconfigurability.

Findings

FIRES outperforms conventional STAR-RIS in system performance.

The proposed optimization effectively designs the surface elements.

Fluid-based metasurface enables dynamic radiation control.

Abstract

This letter introduces the concept of fluid integrated reflecting and emitting surface (FIRES), which constitutes a new paradigm seamlessly integrating the flexibility of fluid-antenna systems (FASs) with the dual functionality of simultaneous transmitting and reflecting reconfigurable intelligent surfaces (STAR-RISs). The potential of the proposed metasurface structure is studied though an FIRES-enabled multicast system based on the energy splitting protocol. In this model, the FIRES is divided into non-overlapping subareas, each functioning as a 'fluid' element capable of concurrent reflection and transmission and changing its position of radiation within the subarea. In particular, we formulate an optimization problem for the design of the triple tunable features of the surface unit elements, which is solved via a tailored particle swarm optimization approach. Our results showcase that the proposed FIRES architecture significantly outperforms its conventional STAR-RIS counterpart.