Energy-Efficient Hybrid D-A Precoders Design for mm-Wave Systems

Hybrid digital to analog precoding is widely used in millimeter wave system to reduce power consumption. The radio frequency (RF) chains consume maximum transmitted power, therefore, in this paper optimal number of RF chains are selected to achieve the desired energy efficiency (EE). The novelty of the proposed method is in two folds. First, the optimal number of RF chains are selected by the proposed bisection algorithm. Second, the optimal analog precoder is designed by power iteration algorithm, followed by the digital precoder which is designed by the known least squares method. The effect of the resolution of the phase shifters used in the analog precoder on EE is investigated. Simulation results show that the proposed algorithms outperform the existing algorithms in terms of the EE and the achievable capacity. It also showed that the hybrid precoding with an optimal number of quantized bits of resolution attains the best EE performance.