Cooperative Cognitive Non-Orthgonal Multiple Access Under Unreliable Backhaul Connections

In this paper, we investigate the performance of energy-harvesting communications with decode-and-forward relay in the presence of non-orthogonal multiple access (NOMA) multiple access and cognitive radio spectrum sharing. We study three cases of single transmitter single relay and various transmitters and relays with two selection strategies (called as RTST1 and RTST2). Specifically, one source node (macro base station) transmits two symbols to two respective destinations via multiple transmitters and multiple relays under the power constraint of a primary user. We derived the closed-form expressions for the outage probability at two destinations and overall system. The outcomes revealed that the system performances are improved when increases the maximum transmit power at the transmitters, the threshold power affect to the primary user, the backhaul reliability. The system performance is lightly decreased when the power splitting ratio is at too low or too high value.