RIS-aided Wireless Communication with $1$-bit Discrete Optimization for Signal Enhancement

TL;DR

This paper introduces a novel divide-and-sort optimization method for 1-bit RIS in wireless communication, achieving globally optimal phase shifts efficiently and outperforming existing methods in performance and complexity.

Contribution

The paper proposes a new divide-and-sort discrete optimization approach for 1-bit RIS that guarantees global optimality with low computational complexity.

Findings

Achieves better performance--complexity tradeoff.

Guarantees global optimality for 1-bit RIS phase shifts.

Has time complexity of O(N log N).

Abstract

In recent years, a brand-new technology, reconfigurable intelligent surface (RIS) has been widely studied for reconfiguring the wireless propagation environment. RIS is an artificial surface of electromagnetic material that is capable of customizing the propagation of the wave impinging upon it. Utilizing RIS for communication service like signal enhancement usually lead to non-convex optimization problems. Existing optimization methods either suffers from scalability issues for $N$ number of RIS elements large, or may lead to suboptimal solutions in some scenario. In this paper, we propose a divide-and-sort (DaS) discrete optimization approach, that is guaranteed to find the global optimal phase shifts for $1$-bit RIS, and has time complexity $\mathcal{O}(N \log(N))$. Numerical experiments show that the proposed approach achieves a better ``performance--complexity tradeoff'' over other methods for $1$-bit RIS.