Beyond Intelligent Reflecting Surfaces: Reflective-Transmissive Metasurface Aided Communications for Full-dimensional Coverage Extension

TL;DR

This paper introduces an intelligent omni-surface (IOS) that can both reflect and transmit signals, significantly extending wireless coverage compared to traditional reflective-only surfaces, through optimized phase shift design.

Contribution

It proposes a novel IOS-assisted communication system capable of full-dimensional coverage extension, with an optimized phase shift design and a branch-and-bound algorithm.

Findings

IOS significantly extends coverage compared to IRS.

Optimized phase shifts improve spectral efficiency.

Simulation confirms coverage enhancement with IOS.

Abstract

In this paper, we study an intelligent omni-surface (IOS)-assisted downlink communication system, where the link quality of a mobile user (MU) can be improved with a proper IOS phase shift design. Unlike the intelligent reflecting surface (IRS) in most existing works that only forwards the signals in a reflective way, the IOS is capable to forward the received signals to the MU in either a reflective or a transmissive manner, thereby enhancing the wireless coverage. We formulate an IOS phase shift optimization problem to maximize the downlink spectral efficiency (SE) of the MU. The optimal phase shift of the IOS is analysed, and a branch-and-bound based algorithm is proposed to design the IOS phase shift in a finite set. Simulation results show that the IOS-assisted system can extend the coverage significantly when compared to the IRS-assisted system with only reflective signals.