A general hybrid precoding scheme for millimeter wave massive MIMO systems

In massive multiple-input multiple-output systems, due to high cost and power consumption, unconstrained fully digital precoding is excluded for its requirement of dedicated radio-frequency (RF) chains per antenna element. Therefore, hybrid digital/analog precoding solution is deemed as the most potential candidate. In this paper, based on the singular value decomposition (SVD) technique, a low-complexity yet high performance precoding strategy is proposed. Specifically, through the operation of the SVD technique on the fully digital precoding matrix, the eigenvectors with the same number of the data streams are selected out to capture the angle information of the analog phase shifters. To obtain the remaining required eigenvectors, the relativity information between the left decomposed matrix and the optimal fully digital precoding matrix is exploited. In this way, the resultant hybrid analog/digital precoding is realized in a low complexity manner. Simulation results show that the spectral efficiency achieved by our proposed scheme is better compared to that with the orthogonal-matching-pursuit (OMP) scheme in most of the practical scenarios when the number of data streams is equal to that of RF chains, and is very close to that by the OMP scheme when the number of data stream is less than that of RF chains.