PLS-RSMA system: An eavesdropping perspective

Pengpai Xu, Ye Fan, Rugui Yao +1 more

Khushi Lal, Chhagan Charan

Pradosh Kumar Hota, Deepak Mishra, Ravikant Saini +1 more

Rate-splitting multiple access (RSMA) is a technique that is widely used in next-generation wireless systems to efficiently manage multiple users. RSMA splits the transmission into two parts using rate splitting, which increases spectral efficiency. However, this technique also makes a portion of the transmission vulnerable to eavesdropping, which can compromise information security. This vulnerability is not limited to external eavesdroppers but also includes internal eavesdropping among users who share the same transmission. Therefore, there is an increasing need to develop secure RSMA systems to address these critical security issues among untrusted users. This paper focuses on a single-antenna RSMA downlink system with multiple untrusted users undergoing Rician channel fading. In this novel system framework considered for performance analysis, each user interprets its own common and private streams while attempting to eavesdrop on the private streams of other users. We evaluate the system-level performance in practical settings involving line-of-sight (LoS) paths using the Rician channel model and derive a tight closed-form approximate expression of the ergodic secrecy rate. Finally, we conduct numerical simulations to validate the theoretical analysis and provide valuable insights into the critical system parameters that impact the achievable ergodic secrecy performance of the RSMA system with untrusted users.

Mahtab Mirmohseni, Panos Papadimitratos

Chang Liu, Junji Pan, Zheng Xue +2 more

In this paper, we propose a novel grouping-based rate splitting multiple access (G-RSMA) against internal eavesdroppers (Eves). Specifically, after users are grouped, their messages are split and encoded into inner-group common and private streams. The inner-group common streams could achieve the dual use: they deliver designated information to legitimate users and serve as artificial noise (AN) to Eves. To ensure the security among users in the presence of internal Eves, our approach maximizes the minimum secrecy rate (MSR) of all legitimate users in the system, which is formulated as a non-convex problem. We tackle it with a novel algorithm leveraging successive convex approximation (SCA), enabling efficient optimization of the transmit precoding scheme. Numerical results show that the G-RSMA approach enhances the MSR performance compared with the one-layer rate splitting multiple access (RSMA) or space division multiple access (SDMA), validating its effectiveness in securing RSMA systems against internal eavesdropping.

Jouana H. Hassan, Ibrahim Khalil Sileh