Design of Hybrid Precoding for Millimeter-Wave Massive MIMO System

In order to improve the spectral efficiency of hybridly-connected hybrid precoding, the optimal hybrid precoding matrix under the ideal conditions was firstly obtained by using the principle of successive interference cancellation. Secondly, the optimal hybrid precoding matrix was decomposed into the digital precoding matrix and the analog precoding matrix by using the gradient descent theory. Finally, considering the constant modulus constraint condition of the analog precoding matrix, the digital and analog precoding matrices were optimized by using the alternating minimization method aim to maximize the spectral efficiency. Due to the hybridly-connected structure, the proposed hybrid precoding design algorithm is significantly superior to the partially-connected and fully-connected hybrid precoding in terms of the system energy efficiency. Meanwhile, the algorithm does not increase any hardware complexity and only increases a small amount of computation of the hybrid-connected hybrid precoding.