Covert performance analysis in IRS-assisted RSMA systems with imperfect SIC

Abstract

Covert communication serves as a pivotal technology for safeguarding wireless communication security. To fortify communication security, this paper introduces a covert communication framework leveraging intelligent reflecting surface (IRS)-assisted rate-splitting multiple access (RSMA), while accounting for imperfect successive interference cancellation (SIC). RSMA operates by partitioning the intended information into common and private components, which are then transmitted through superposition coding. In this system architecture, the base station utilizes IRS to facilitate the transmission of superimposed signals to both covert and legitimate user, where the common signals and legitimate user’s private signals act as transmission cover for the covert user’s private data streams. To evaluate system performance, we derive an approximate expression of detection error probability (DEP), and then calculate the outage probability (OP) of users decode their respective signals. Finally, we maximize the system’s covert rate by balancing network reliability and covertness requirements. Simulation results reveal that imperfect SIC introduces significant performance degradation and these detrimental effects can be effectively alleviated through increasing IRS elements. Additionally, the numerical results also demonstrate that the proposed IRS-assisted RSMA scheme is superior to the conventional RSMA scheme and IRS-assisted NOMA scheme.