Uplink and Downlink MIMO-NOMA With Simultaneous Triangularization

In this paper, we consider the uplink and downlink precoder design for two-user power-domain multiple-input multiple-output (MIMO) non-orthogonal multiple access (NOMA) systems. We propose novel precoding decoding schemes that lower complexity at receiver by decomposing MIMO-NOMA channels of users into single-input single-output (SISO)-NOMA via simultaneous triangularization (ST) MIMO a low-complexity self-interference cancellation receiver. The proposed ST avoid channel inversion transmitter take advantage null spaces users, which is beneficial ergodic achievable rate performance. characterize maximum regions schemes, compare them with respective upper bounds, baseline orthogonal (OMA). Our results illustrate significantly outperform considered OMA, have small gap to bounds most conditions user rates. Moreover, show hybrid scheme, performs time sharing between single-user MIMO, can improve performance even further.