Outage and ergodic sum-rate performance of cooperative MIMO-NOMA with imperfect CSI and SIC

Abstract

In this paper, we examine a half-duplex cooperative multiple-input multiple-output non-orthogonal multiple access system with imperfect channel state information (CSI) and successive interference cancelation. The base station (BS) and mobile users with multi-antenna communicate by the assistance of a CSI based or fixed gain amplify-and-forward (AF) relay with a single antenna. The diversity schemes, transmit antenna selection, and maximal ratio combining are applied at the BS and mobile users, respectively. We study the system performance in terms of outage probability (OP) and ergodic sum-rate. Accordingly, the exact OP expressions are first derived jointly for the CSI based and fixed gain AF relay cases in Nakagami-m fading channels. Next, the corresponding lower and upper bound expressions of the OP are obtained. The high signal-to-noise ratio analyses are also carried out to demonstrate the error floor value resulted in the practical case and achievable diversity order and array gain in the ideal case. Moreover, the lower and upper bounds of the ergodic sum-rate expressions are derived together for the CSI based and fixed gain AF relay cases. Finally, the Monte-Carlo simulations are used to verify the correctness of the analytical results.