On The Optimal Number of Reflecting Elements for Reconfigurable Intelligent Surfaces

TL;DR

This paper investigates the optimal number of elements in reconfigurable intelligent surfaces to maximize communication performance, considering trade-offs with energy efficiency and resource overhead, supported by numerical validation.

Contribution

It introduces an optimization framework for determining the ideal number of surface elements, accounting for practical overheads and phase optimization.

Findings

Identifies the optimal number of elements for maximum system rate.

Demonstrates significant potential gains of intelligent surfaces.

Validates the proposed optimization through numerical results.

Abstract

This work considers a point-to-point link where a reconfigurable intelligent surface assists the communication between transmitter and receiver. The system rate, energy efficiency, and their trade-off are optimized with respect to the number of individually tunable elements of the intelligent surface. The resource allocation accounts for the communication phase and for the overhead due to channel estimation and to reporting the optimized resource allocation to the intelligent surface. Numerical results confirm the optimality of the proposed methods and show the potential gains of reconfigurable intelligent surfaces.