PLS-RSMA system: An eavesdropping perspective

Abstract

This paper studies the physical layer security (PLS) of a rate-splitting multiple access (RSMA) system over Nakagami-m fading channels. Unlike existing works, we focus on the eavesdropper (Eve) perspective, considering both passive and active jamming scenarios due to the uncertainty of Eve behavior. For a fair comparison, we introduce the concept of effective power (EP) for the overall PLS-RSMA system. In the passive eavesdropping case, EP is equivalent to the transmit power at the base station (BS), whereas in the active jamming case, EP is defined as the power gap between the BS and Eve. Considering the effects on the EP and Eve location, closed-form expressions of the security outage probability (SOP) are respectively derived for both considered scenarios. Simulation results corroborate our analysis, indicating that when EP is lower or Eve is farther from the BS, the probability of Eve attacking legitimate users is higher. On the contrary, a closer Eve tends to wiretap information directly from the BS. These findings provide valuable insights for predicting and implementing effective protection mechanisms for the PLS-RSMA system.