Multi-Pair D2D Communications Aided by An Active RIS over Spatially Correlated Channels with Phase Noise

TL;DR

This paper analyzes a multi-pair D2D communication system aided by an active RIS with phase noise, deriving ergodic sum rate expressions and proposing a genetic algorithm for optimization, demonstrating active RIS's superiority over passive RIS.

Contribution

It provides the first closed-form ergodic sum rate expressions for multi-pair D2D with active RIS under phase noise and develops a GA-based optimization method.

Findings

Active RIS outperforms passive RIS in sum rate.

Derived closed-form ergodic sum rate expressions.

Proposed genetic algorithm effectively maximizes sum rate.

Abstract

This paper investigates a multi-pair device-to-device (D2D) communication system aided by an active reconfigurable intelligent surface (RIS) with phase noise and direct link. The approximate closed-form expression of the ergodic sum rate is derived over spatially correlated Rician fading channels with statistical channel state information (CSI). When the Rician factors go to infinity, the asymptotic expressions of the ergodic sum rates are presented to give insights in poor scattering environment. The power scaling law for the special case of a single D2D pair is presented without phase noise under uncorrelated Rician fading condition. Then, to solve the ergodic sum rate maximization problem, a method based on genetic algorithm (GA) is proposed for joint power control and discrete phase shifts optimization. Simulation results verify the accuracy of our derivations, and also show that the active RIS outperforms the passive RIS.