Robust Beamforming Design for RSMA-Integrated Full-Duplex Communications: Energy and Spectral Efficiency Trade-Off

In this paper, we investigate an unconventional full-duplex (FD) integrated rate-splitting multiple access (RSMA) scheme for improved spectral efficiency (SE) and energy efficiency (EE) performance when compared to the conventional power-domain schemes. In particular, we focus on improving the energy efficiency (EE) and spectral efficiency (SE) trade-off for the multiple users subject to robust beamforming design and smart inter-user interference mitigation under imperfect channel state information (CSI). We formulate a multi-objective optimization (MOO) problem, specifically aiming to jointly maximize EE and SE within the FD-RSMA system by jointly optimizing the resource allocation subject to the limits on transmit power and minimum rate, under the assumption of a CSI error model with a bound. Initially, the MOO problem is converted into a single objective optimization (SOO) problem using the weighted sum method, with a trade-off parameter. An iterative algorithm is employed, utilizing successive convex approximation and the S-procedure to achieve near-optimal resource allocation for the transformed SOO problem, with a particular emphasis on effective interference management. Simulation results highlight the effectiveness of the FD-RSMA scheme, demonstrating its superiority over the multi-user FD space division multiple access by 16.93 % and non-orthogonal multiple access scheme by 76.04 %.