Intelligent reflecting surface-assisted cognitive radio-inspired rate-splitting multiple access systems

Abstract

Intelligent reflecting surface (IRS) has been widely regarded as a promising technology for configuring wireless propagation environments. In this paper, we utilize IRS to assist transmission of a secondary user (SU) in a cognitive radio-inspired rate-splitting multiple access (CR-RSMA) system in which a primary user's (PU's) quality of service (QoS) requirements must be guaranteed. Without introducing intolerable interference to deteriorate the PU's outage performance, the SU conducts rate-splitting to transmit its signal to the base-station through the direct link and IRS reflecting channels. For the IRS-assisted CR-RSMA (IRS-CR-RSMA) scheme, we derive the optimal transmit power allocation, target rate allocation, and successive interference cancellation decoding order to enhance the outage performance of the SU. The closed-form expression for the SU's outage probability achieved by the IRS-CR-RSMA scheme is derived. Various simulation results are presented to clarify the enhanced outage performance achieved by the proposed IRS-CR-RSMA scheme over the CR-RSMA scheme.