A low-complexity iterative algorithm for multiuser millimeter-wave systems

In this paper, we design a low-complexity multiuser millimeter-wave massive-multiple-input-multiple-output system with the help of a hybrid analog/digital precoding architecture. Hybrid precoding is used to reduce the hardware cost and power consumption of millimeter-wave large-scale antenna systems. In this manner, we proposed a novel approach to solve the well-known zero-forcing algorithm by using an iterative optimization method called the conjugate gradient method. The problem is transformed into an optimization problem, and the complex matrix inverse operation required in the zero-forcing algorithm is eliminated. Hence, the complexity of the zero-forcing algorithm is reduced while the spectral efficiency is maintained at the same level as that of the reference zero-forcing detector. The simulation results demonstrate that the proposed conjugate gradient-based algorithm achieves better performance than competing methods in terms of complexity and spectral efficiency.