Impact of Interference on the Performance of RIS-Assisted Source DF Relaying Networks

TL;DR

This paper analyzes how co-channel interference affects RIS-assisted decode-and-forward relaying networks, deriving outage probability formulas and showing that relay count impacts diversity more than the number of reflecting elements, with RIS at the source mitigating interference.

Contribution

It provides new closed-form expressions for outage probability in RIS-assisted DF relaying networks under interference, highlighting the roles of relays and reflecting elements.

Findings

Relay number K influences diversity order significantly.

Number of reflecting elements N has minimal effect on diversity.

RIS at the source helps mitigate interference effects.

Abstract

This letter investigates the impact of co-channel interference (CCI) on the performance of a decode-and-forward (DF) relaying network with a reconfigurable intelligent surface (RIS)-assisted source. We consider one source, multiple DF relays, and one destination with CCI at both the relays and destination. We derive closed-form accurate approximations for the system outage probability assuming Rayleigh fading channels. In addition, we study the system performance at the high signal-to-noise ratio (SNR) regime, where closed-form expressions are derived for the asymptotic outage probability, diversity order, and the coding gain. The results show that the number of reflecting elements N at the source has a small effect on the coding gain of the system and not on the diversity order. Furthermore, findings illustrate that the number of relays K is affecting the diversity order and is more impactful on the performance than N. Finally, results show that utilizing RIS at the source node mitigates the interference effect at the relay nodes.