Spectral Efficiency Optimization of Uplink Millimeter Wave MIMO-NOMA Systems

Abstract

In this paper, we considered uplink communication, focusing on the improvement of spectral efficiency (SE) for millimeter wave (mmWave) multiple-input multiple-output non-orthogonal multiple access (MIMO-NOMA) systems. Firstly, we proposed an adaptive cluster head selection algorithm. Then, a channel-aligned analog beamforming scheme was designed based on the selected cluster heads. After that, the user grouping algorithm was designed based on the user-equivalent channel correlation. Subsequently, the power allocation problem was transformed from a nonconvex problem to a convex one using the quadratic transformation (QT) method considering all relevant constraints. Finally, the optimal user power allocation and digital beamforming design was obtained by iteratively optimizing the power and digital beamforming. Simulation results show that our proposed scheme can achieve a higher SE than existing methods.

Efficient Precoding and Power Allocation Techniques for Maximizing Spectral Efficiency in Beamspace MIMO-NOMA Systems

“…Additionally, they derive a tight closed-form formula for optimal spectral efficiency using KKT analysis. In [ 15 ], from the perspective of spectral efficiency, the authors propose a joint optimization framework and employ the quadratic transformation (QT) method to convert the non-convex power allocation problem into a convex problem. They also design an iterative approach to obtain optimal power allocation and digital beamforming.…”