A Coordinated Direct AF/DF Relay-Aided NOMA Framework for Low Outage

This paper investigates the performance of a new framework for low-outage downlink non-orthogonal multiple access (NOMA) using coordinated direct and relay transmission (CDRT) scheme with links to both near-user (NU) far-user (FU). Both amplify-and-forward decode-and-forward relays are considered. In this framework, NU combines signals from base-station at each stage successive interference cancellation (SIC) attain good outage performance. For FU, expressions probability throughput derived in closed form. We also derive high-SNR demonstrate that proposed users harness diversity two without feedback bits (this is only achieve this). choice power allocation coefficient target symbol rates crucial maximizing while ensuring desired FU throughput. CDRT outperforms known schemes terms probability, sum throughput, energy efficiency. Moreover, we show optimal rate selection important maximize Monte Carlo simulations validate accuracy analytical expressions.