Energy Efficiency Optimization for Symbol-Level Precoding-Aided RSMA MIMO System

Rate-splitting multiple access (RSMA) decomposes transmitted signals into common and private streams, employing successive interference cancellation (SIC) to cancel interference from common to private streams, thereby improving robustness under diverse channel conditions. Conventional RSMA implementations based on linear precoding do not actively employ residual interference, while symbol-level precoding (SLP) and certain interference-aware techniques provide one promising pathway for further interference exploitation. This work presents three key contributions: (1) we introduce a two-stage interference coordination framework, which first eliminates common signal interference through SIC, and then utilizes the constructive interference; (2) we integrate the SLP design with interference exploitation to formulate an energy efficiency maximization problem; (3) we develop an optimization algorithm for the non-convex problem in RSMA-SLP systems, which decomposes the original formulation into tractable problems via fractional programming for efficient iterative solutions. Our simulation confirms that the proposed scheme not only enhances system robustness but also improves energy efficiency through interference exploitation and verifies that the proposed scheme outperforms existing multiple-access precoding methods.