Rate Splitting With Finite Constellations: The Benefits of Interference Exploitation vs Suppression

Rate-Splitting (RS) has been shown recently to be a powerful approach for the design of non-orthogonal transmission, multiple access, and interference management strategies in multi-user multi-antenna systems. RS, through split messages into common private parts, relies on transmission streams decoded by all users, only its intended user. This enables RS bridge extreme fully decode treat as noise. In this paper, we depart from Gaussian signaling study under finite input alphabet system propose constructive (CI) exploitation further enhance sum-rate achieved RS. To that end, new analytical expressions ergodic are derived two precoding techniques messages, namely, 1) traditional suppression zero-forcing (ZF) approach, 2) closed-form CI approach. Our analysis is presented perfect channel state information at transmitter (CSIT), extended imperfect CSIT knowledge. A novel power allocation strategy, specifically suited setup, lead superior performance over conventional linear not relying (NoRS). The results work validate significant gain with ZF NoRS.