Outage Analysis of SWIPT-Enabled Multi-Relay Aided Full-Duplex NOMA System under Partial Relay Selection

Abstract

This paper considers a multi-relay aided full-duplex (FD) cooperative non-orthogonal multiple access (NOMA) system integrated with simultaneous wireless information and power transfer (SWIPT) technique, which consists of a base station (BS), $N$ FD relays and two downlink NOMA users. We propose variable transmit power allocation (VTPA), where the power allocation factor at the BS and the time switching (TS) factor at the selected relay are chosen adaptively so as to improve the performance of the downlink users in the system. Assuming partial relay selection (PRS) scheme, analytical expressions are derived for the outage probabilities (OP) of the downlink users under VTPA and constant transmit power allocation (CTPA) schemes. To gain more insights, we describe the asymptotic OP (AOP) analysis as well. We show that the proposed VTPA scheme can mitigate the outage floor present in FD-NOMA system under CTPA and significantly improve the OP performance of the downlink users.