Energy-Efficient Power Allocation Scheme for Hybrid Precoding mmWave-NOMA System with Multi-User Pairing

In the fifth generation (5G) wireless communications, non-orthogonal multiple access (NOMA) has been recently considered in millimeter-wave (mmWave) communication systems to support more users and further enhance the spectrum efficiency (SE) and energy efficiency (EE). Therefore, in this paper, we investigate the EE power allocation scheme for the mmWave communications with NOMA (mmWave-NOMA) system with multi-user pairing. We first pair users according to their channel difference and correlation, then perform a two-stage hybrid precoding design. Following this, we formulate the EE maximization problem for the proposed system model. An iterative algorithm based on coordinate descent (CD) is proposed to obtain a sub-optimal power allocation. Simulation results show that the proposed power allocation scheme can attain pretty high EE performance with relatively low complexity.