Power Allocation for Cognitive Radio Networks Employing Non-orthogonal Multiple Access

In this paper, the power allocation (PA) problem is investigated in cognitive radio networks (CRNs), employing non-orthogonal multiple access (NOMA) technique. In such a framework, the quality of service (QoS) requirements for both the primary users (PUs) and secondary users (SUs) should be met. We propose a novel PA algorithm, which fully exploits the characteristics of NOMA-based system. The QoS requirements for PUs are guaranteed through the setup of the overall power for SUs. In addition, it provides PA in a descending order, according to SUs' channel gains. It is validated that the proposed algorithm is optimal. To show its effectiveness, it is compared with one of the most efficient PA algorithms, namely fractional transmit power control (FTPC). The superiority of the proposed algorithm is thoroughly verified by simulation results. Additionally, the computational complexity of our proposed algorithm is only linear, i.e., O (N)