An Iterative Method for ASC Hybrid Precoding Structure for mmWave Ma-MIMO Systems

The use of millimeter wave (mmWave) massive multiple input multiple output (Ma-MIMO) systems makes it possible to meet the essential needs of future generation wireless systems and solve the impending wireless network crisis. The mmWave Ma-MIMO Technique offers higher numbers of antennas and carrier frequencies. Hybrid precoding is considered as a key technique for the practical deployment of mmWave Ma-MIMO systems, since it significantly decreases the implementation costs, energy consumption, and hardware complexity. The large using of mmWave Ma-MIMO technologies in future generation wireless systems, causes imperative develop cost-effective hybrid precoding solutions that match the various application cases of these systems.  The fully-connected structure can offer spectral efficiency (SE) close to the fully-digital precoding but, unfortunately with high energy consumption. Furthermore, the sub-connected structure with reduced power consumption, provides poor SE. Therefore, the trade-off between SE and energy efficiency (EE), can be made, and in this paper, we consider an adaptive sub-connected (ASC) hybrid precoding structure, where a switch network is able to provide dynamic connections from phase shifters to radio frequency (RF)chains. The simulation results indicate that in terms of SE, the proposed algorithm with ASC structure obtains higher performance than the sub-connected structure. As a result, since the ASC structure reduces the number of phase shifters, it can offer a better EE compared to the sub-connected structure.