Performance Analysis of Nonorthogonal Multiple Access for Downlink Networks With Antenna Selection Over Nakagami-m Fading Channels.

We investigate the system performance of a nonorthogonal multiple access (NOMA) based downlink amplify-and-forward relay network over Nakagami-$m$ fading channels with imperfect channel state information, where the base station and all users are provided with multiple antennas, while the relay is equipped with a single antenna. Two special conditions of interest (e.g., Nakagami-1, i.e., Rayleigh and Nakagami-2) are analyzed, and closed-form expression for the system outage probability is derived. Moreover, tight lower and upper bounds of the outage probability, and the outage probability in the high signal-to-interference-and-noise ratio regime, i.e., in the presence of error floor, which exists due to the channel estimation errors, are obtained. Finally, computer simulations are conducted to verify the accuracy of the numerical analysis and to confirm the superiority of the antenna selection and NOMA scheme. [ABSTRACT FROM PUBLISHER]