Rate Splitting Approach Under Psk Signaling Using Constructive Interference Precoding Technique

Rate-Splitting (RS) approach has been proposed recently to enhance the performance of multi-user multiple-input multiple-output (MU-MIMO) systems. In RS a user message is split into common and private parts, where the common message can be decoded by all users, while the private one can be decoded only by the intended user. In addition, constructive interference (CI) precoding technique has shown to provide significant performance benefits in different multi-user scenarios. In this paper we propose employing the CI concept to further enhance the sum-rate achieved by RS approach in MU-MIMO systems under a phase-shift keying (PSK) input alphabet. In light of this and in order to provide fair comparison, new analytical expressions for the average sum-rate are derived for two precoding techniques of the private messages, namely, 1) CI precoding technique, 2) zero forcing (ZF) precoding technique. In addition, the conventional transmission, without using RS (NoRS) is also studied in this paper. Monte-Carlo simulations are provided throughout to confirm the analysis. The results in this work validate the significant sum-rate gain of RS with CI over the conventional RS with ZF technique.