A Rate-Splitting Approach for RIS-Aided Massive MIMO Networks with Transceiver Design

Reconfigurable intelligent surface (RIS), consisting of a large number of passive elements, is an important technology in improving spectral efficiency. In parallel, rate-splitting (RS) is a technique that reduces the detrimental effect of multiuser interference by splitting one users’ message into a private and a common part. In this work, we introduce the study of RS in downlink RIS assisted massive multiple-input multiple-output (mMIMO) systems. We compare the sum-rate under different channel status information (CSI) conditions, such as perfect CSI and statistical CSI. Unlike the traditional system with the RS strategy, users in our system have multiple antennas. Also, we propose an iterative algorithm to design the transceiver, such as the precoder and the combiner by using the minimum mean-squared error (MMSE) method. The RS and the traditional broadcasting (BC) methods are compared in simulations, which show that the RS method can also improve the sum-rate in the multiple-antenna system.