Modeling and analysis of self-interference impaired two-user cooperative MIMO-NOMA system

Abstract

In this work we deal with the performance analysis of a cell-edge user with the precoder and equalizer design in a two-user cooperative multiple-input multiple-output non-orthogonal multiple access (MIMO-NOMA) system. Since the data rate fairness and outage performance of cell-edge user are crucial issues in MIMO-NOMA systems, we emphasize on how to sort out these issues. To this end, the coefficients of power allocation are updated with the help of beamformers by utilizing the simultaneous wireless information and power transfer (SWIPT) protocol. Particularly, a user at the cell-center plays the role of a relay to help the cell-edge user and the relaying operation is powered by a hybrid time switching/power splitting SWIPT protocol. For this purpose, first we formulate the signal-to-interference-plus noise ratio of downlink MIMO-NOMA system by considering distinct correlation matrices in term of indefinite eigenvalues by utilizing a quadratic formulation in the presence of both self-interference and multi-user interference. Next, a closed-form expression of the outage probability is derived based on the knowledge of receive and transmit correlation matrices at the transmitter side. The analytical expressions are validated through simulations to affirm the accuracy of our analysis. We showcase the extent by which the cell-edge user’s outage performance is improved by using the antenna diversity at near and far end terminals of the MIMO-NOMA system.