Problems of Combining NOMA with MIMO

This article reviews existing methods for combining non-orthogonal access technology (NOMA) and multiple input – multiple output (MIMO), and analyzes the results of current research in this area. Developing new MIMO-NOMA systems brings new signal processing and formation challenges such as grouping of users’ signals and complexity of their joint processing. Along with MIMO-NOMA multi-cluster systems, open loop and closed loop systems are considered. Simulation results are presented to compare the noise immunity of users with different type of modulation scheme selected in one cluster of closed loop and open loop MIMO-NOMA system for independent Raleigh fading channel. The main problems associated with the development of methods and algorithms for combining NOMA and MIMO technologies are also formulated.