Robust Wide-Beam Analog Beamforming With Inaccurate Channel Angular Information

Hybrid precoding is widely used in millimeter wave massive multiple-input multiple-output system to reduce the hardware complexity. Previous works have shown that hybrid precoding by using angular information can acquire good performance. However, in practice, perfect angular information is hard to be obtained. In this work, a robust analog beamforming method based on chirp sequence is proposed to deal with the inaccurate angle estimations. Our method can adjust the beamwidth arbitrarily, and the optimal beamwidth is derived according to the SNR and angle estimation error variance. Simulation results show that the method can dramatically improve user fairness and cell-edge user rates.