An Adaptive Scheme for Energy Buffer-Aided Wireless-Powered Cooperative NOMA System

In this paper, an adaptive scheme for energy buffer-aided wireless-powered cooperative non-orthogonal multiple access (NOMA) system is proposed. In the proposed system, near users (NUs) and far users (FUs) first collect and store radio frequency (RF) based energy from the base station (BS) in the downlink. Then, the N NUs and N FUs are paired two by two for optimal combination, and the information is delivered to the BS by switching between NOMA, cooperative NOMA (CNOMA) and orthogonal multiple access (OMA) signaling. Moreover, an energy management policy is considered at the NUs and FUs, namely the best-effort policy (BEP). The outage probability and throughput expressions of the proposed system with BEP are derived over Rayleigh fading channels. Results reveal that the proposed system can significantly improve the performance of FUs compared to the energy buffer aided wireless-powered NOMA system, and outperform the buffer-less wireless-powered CNOMA system.