Cooperative NOMA with AF Relaying over Nakagami-m Fading in a D2D Network

Abstract

Cooperative non-orthogonal multiple access (NOMA) scheme is emerging as an important part of the next generation wireless systems. Recently, device-to-device (D2D) networks with NOMA have received considerable attention by the researchers due to the advantages offered by them. D2D communication involves direct contact between the devices in proximity and the devices can also be used as relays for cooperative communication. In this paper, we present the performance analysis of a downlink cooperative D2D network with NOMA and amplify-and-forward (AF) relaying with fixed gain assuming that the D2D communication links experience independent Nakagami-m fading. We derive closed-form expressions for the outage probability of strong and weak D2D users with the assumption that there exists a direct communication link between the base station and the D2D users. Further, we also present the system throughput and the asymptotic outage analysis for both strong D2D user and weak D2D user. As a special case, we also provide the outage expressions for both strong D2D user and weak D2D user when the D2D communication links experience Rayleigh fading. Furthermore, numerical results are in agreement with the derived analytical expressions.