On the Performance of NOMA Power Control Scheme in Cognitive Radio Networks

Abstract

In this paper, we studied the power allocation (PA) of Non-orthogonal multiple access (NOMA) for secondary users (SUs) in a Cognitive Radio Network (CRN). In the proposed scheme, SUs produce interference to the Primary Users (PUs) belonging to a heterogeneous mixed network, conformed by Long Term Evolution (LTE) and Wireless Fidelity (WiFi) technologies, main characteristics of 5G communications. The Signal-to-interference-plus-noise ratio (SINR) of the SUs must also be greater than the predefined threshold, otherwise, an interruption occurs and the Probability of non-Detection (PnD) of PU increases, decaying the total bit rate and the spectral efficiency of the link. In order to improve the spectral efficiency and the PnD of the system, a NOMA power control scheme is proposed to be adapted to the CRN. The optimal power allocation coefficients of SUs are derived through a proposed optimization algorithm. The numerical results show that the proposed scheme outperforms other conventional schemes (OMA-OFDM, Cooperative OMA and OMA-TDMA schemes) in terms of spectral efficiency and PnD.