Resource Efficient and Robust RSMA for Visible Light Communications

Spectral efficiency (SE) and energy efficiency (EE) are two main metrics for the transmit design in Visible Light Communications (VLC). However, the SE-optimal and EE-optimal strategies may be in conflict with each other to some extent. In this paper, we investigate the the tradeoff between EE and SE in rate splitting multiple access (RSMA)-aided VLC systems to maximize the system resource efficiency (RE) taking both perfect and imperfect channel state information (CSI) into consideration. For the scenarios with perfect CSI, we explore the joint precoding design and common rate allocation to maximize the RE of RSMA-aided VLC systems under the constraints of quality of service (QoS) and linear operation region (LoR) of LED, and propose a primal-dual-gradient-based precoding strategy. Furthermore, in the presence of CSI estimation errors, we propose a worst-case robust precoding design by exploiting quadratic transform and $\mathcal {S}$-Procedure. Numerical results indicate that the proposed resource efficient RSMA algorithm achieves the tradeoff between EE and SE.