Flat-Top Beamforming with Efficient Array-Fed RIS

TL;DR

This paper introduces a new flat-top beamforming design for array-fed RIS that improves energy efficiency and deployment practicality, supporting wide-angle uniform power distribution for next-generation wireless systems.

Contribution

A pragmatic flat-top beam design method for array-fed RIS that outperforms existing techniques in efficiency and feasibility, advancing sustainable wireless communication technologies.

Findings

Outperforms current state-of-the-art in flat-top beam design

Enhances energy efficiency and deployment feasibility

Supports applications like beaconing and hierarchical beamforming

Abstract

Flat-top beam designs are essential for uniform power distribution over a wide angular sector for applications such as 5G/6G networks, beaconing, satellite communications, radar systems, etc. Low sidelobe levels with steep transitions allow negligible cross sector illumination. Active array designs requiring amplitude taper suffer from poor power amplifier utilization. Phase only designs, e.g., Zadoff-Chu or generalized step chirp polyphase sequence methods, often require large active antenna arrays which in turns increases the hardware complexity and reduces the energy efficiency. In our recently proposed novel array-fed reflective intelligent surface (RIS) architecture, the small ($2 \times 2$) active array has uniform (principal eigenmode) amplitude weighting. We now present a pragmatic flat-top pattern design method for practical array (RIS) sizes, which outperforms current state-of-the-art in terms of design superiority, energy efficiency, and deployment feasibility. This novel design holds promise for advancing sustainable wireless technologies in next-generation communication systems, including applications such as beaconing, broadcast signaling, and hierarchical beamforming, while mitigating the environmental impact of high-energy antenna arrays.