Power Allocation for Uplink Cognitive Heterogeneous Network with Nonorthogonal Multiple Access

In this paper, we propose an optimal power allocation scheme in an uplink two-tier heterogeneous cognitive network with non-orthogonal multiple access (NOMA). Secondary users (SUs) in femtocell tier are allowed to access the licensed frequency band owned by macrocell tier in underlay spectrum sharing mode, which causes severe cross-tier interference. We propose an optimal power allocation scheme by considering the cross-tier interference control from the femtocell tier to the macrocell tier and adopting successive interference cancellation (SIC) to improve the spectrum efficiency within the femtocell tier. The effectiveness of the proposed power allocation scheme on the performance of spectrum efficiency and cross-tier interference mitigation validates by simulation.