Hardware-Efficient Hybrid Precoding and Power Allocation in Multi-User mmWave-NOMA Systems

In this paper, we propose a hardware-efficient hybrid precoding (HP) scheme and resource allocation strategy for millimeter-wave non-orthogonal multiple access (NOMA) communication system. Specifically, we utilize a switch and inverter (SI) network to realize the phase shift operation of HP structure (referred to as SIHP structure). A user clustering scheme is first formulated according to the channel correlation and gain difference of the users. Based on this, we design a two-step HP scheme for the proposed HP structure. With these results, a power allocation problem is formulated to maximize the overall achievable rate under per-cluster' power constraint and peruser' quality of service requirement. Then, we propose a power allocation algorithm with intra-cluster power allocation and inter-cluster power allocation strategies to obtain the sub-optimal power allocation. Simulation results verify that the proposed mmWave-NOMA system with SIHP obviously outperforms the mmWave-NOMA system with traditional HP in terms of energy efficiency.