Channel Estimation and Transmission Strategy for Hybrid mmWave NOMA Systems

This paper presents a novel channel estimation and transmission strategy for millimeter wave (mmWave) non-orthogonal multiple access communication system with hybrid architecture. We first propose a general iterative index detection-based channel estimation algorithm that can obtain both direction of arrival and channel gain of each channel path. We then design an enhanced hybrid precoding scheme from the angle domain viewpoint to reduce the inter-beam interferences. Next, we investigate the multi-user scheduling and power allocation with the objective of maximizing the overall achievable rate. The problem turns to be non-convex and then we decompose it into two sub-problems, which separately consider user scheduling and power allocation. The former is solved by a novel algorithm based on the many-to-one two sided matching theory while the latter is solved by an iterative optimization algorithm. Simulation results show that the proposed channel estimation and user scheduling can be better than traditional methods. Finally, numerical examples are provided to corroborate the proposed studies.